Development of Heusler-alloy. based magnetocaloric inks for 2D - 3D printing

DOCTORAL THESIS
DEVELOPMENT OF HEUSLER –
ALLOY – BASED MAGNETOCALORIC
INKS FOR 2D – 3D PRINTING
BOSCO RODRIGUEZ CRESPO
2024
Supe iso s:
D . Daniel Salaza
P o . Volodymy Che nenko
(cc)2024 BOSCO RODRIGUEZ CRESPO (cc by 4.0)
Es e abajo de in es igación pa a op a al G ado de Doc o po la Uni e sidad
del País Vasco (UPV/EHU) se ha ealizado en colabo ación en e el Basque
Cen e o Ma e ials, Applica ions and Nanos uc u es (BCMa e ials), el
Depa amen o de Elec icidad y Elec ónica de la Facul ad de Ciencia y
Tecnología y el ins i u o Funk ionale Ma e ialien (FM) de TU Da ms ad .
Po o o lado, la esis ha sido posible g acias a la inanciación ob enida desde
di e en es uen es a ni el nacional y es a al, como la beca pa a la o mación de
pe sonal in es igado con ins i uciones y emp esas (PIFI20/10) o o gada po
la UPV/EHU.
Asimismo, es a esis ambién ha sido posible g acias a la ayuda inancie a del
Minis e io de Ciencia, Inno ación y Uni e sidades (P oyec o RTI2018-094683-
B-C53-54) y el Depa amen o de Educación del Gobie no Vasco (P oyec o
IT1245-19). También ag adece a la inanciación del Depa amen o de Indus ia
y Educación del Gobie no Vasco median e los p og amas ELKARTEK y
PIBA (PIBA-2018-06).
I
Ag adecimien os
Cuando empecé es e iaje hace poco más de cua o años, nunca imaginé la
p o undidad del comp omiso y las ad e sidades que encon a ía en el camino.
La ealización de es a esis doc o al ha sido una a esía llena de desa íos y
descub imien os, y hoy, al llega al inal de es e capí ulo, me sien o
p o undamen e ag adecido po odas las pe sonas que han sido pa e de es a
expe iencia. Lo más di ícil de esc ibi es as líneas a a se no ol ida de
menciona a odas las pe sonas, pues en es a e apa son muchas con las que he
enido la o una de compa i expe iencias y conocimien os.
En p ime luga , quie o exp esa mi ag adecimien o a mis di ec o es de esis
D . Daniel Salaza y P o . Volodymy Che nenko, pues sin ellos ni su apoyo
nada de es o hubie a sido posible. Su guía expe a, apoyo inqueb an able y
con ianza en mí han sido undamen ales pa a es e log o. Han sido no solo
men o es, sino ambién modelos a segui que me han inspi ado a alcanza mis
me as académicas. Ag adece ambién a mi u o Jon Gu ié ez po su ayuda.
Quie o ag adece ambién a la Fundación BCMa e ials po la g an opo unidad
que me die on pa a pode ealiza allí la esis y a la Uni e sidad del País Vasco
(UPV/EHU) po o o ga me la beca pa a la o mación de pe sonal in es igado
con ins i uciones y emp esas (PIFI20/10).
A mi amilia, a quienes debo an o, quie o ag adece les po su apoyo cons an e.
A mis pad es, po inculca me alo es y p opo ciona me la base sólida desde la
que he podido cons ui mi ca e a p o esional y pe sonal.
En el labo a o io hemos acabando o mando un equipo excepcional de
compañe os y, sob e odo amigos, en e And és G, James R, Ma iana R,
San iago C y los nume osos isi an es y colabo ado es que nos han acompañado
a lo la go de es os años. Cada uno ha apo ado su g ani o de a ena a que cada

II
día i a abaja sea más ameno. Las discusiones in elec uales y no an
in elec uales en los ca és dia ios (la azón eal po la que odos enimos al
abajo) y las colabo aciones que hemos o jado han sido esenciales pa a hace
que la esis sea mucho más dis u able.
La esis ha aído consigo una sucesión de muchos al ibajos los cuales han sido
sob elle ados mucho mejo g acias a la compañía y mo i ación de mis
compañe os. En especial, mi g upo de me ale os me alú gicos, J Napal, A
Reizábal, D Payno, P González, A Ga cía, F Zheng, N Ba oso, P Lazpi a, JM
Po o, N Pe inka, S Lance os, el equipo de adminis ación de BCMa e ials y
odos los compañe os con los que he coincidido y colabo ado.
I also wan o hank o all he people o Funk ionale Ma e ialien (FM) om TU
Da ms ad , ha allowed me o make a h ee mon h s ay in hei cen e , whe e
I had he oppo uni y o wo k wi h people ha a e a wo ld e e ence o he
subjec o my hesis and ha le me wo k in hei acili ies. In special, hank you
P o . D . O Gu leisch, D . K Skoko , D . F Scheibel, D . A Aube , D . S
Ene , K Schä e , B Beckmann, Ra ael G, D . L P eu e , D . L Schä e , M Laux
and all he people ha made my s ay un o ge able.
También quie o ag adece al pe sonal de se icios gene ales de la uni e sidad,
po su g an apoyo y ayuda a la ho a de pode hace uso de sus equipos. A Iñaki
O ue, po las e e nas peleas con el VSM y el SQUID y a Ai o La añaga po
su g an ayuda a la ho a de hace medidas de di acción de ayos X.
Y, po úl imo, pe o no menos impo an e, a Dídac Mesa Romeu, po se el
he mano mayo que nunca u e, y po pe mi i me usa algunas de sus inc eíbles
as o o og a ías noc u nas pa a la con apo ada de la esis y algunos capí ulos.
G acias po habe sido pa e in eg al de es e capí ulo de mi ida.
Con ap ecio since o,
Bosco.
III
Resumen
En la búsqueda de ecnologías de e ige ación sos enibles y e icien es en
ene gía, el es udio de los e ec os caló icos ha su gido como una ía
p ome edo a. Es a esis doc o al se emba ca en una explo ación ex ensa del
e ec o magne ocaló ico, con el obje i o p incipal de pe mi i la imp esión 3D
en able de es uc u as magne ocaló icas u ilizando ma e iales espe uosos con
el medio ambien e. La in es igación aba ca la sín esis de aleaciones Heusle
magné icas con memo ia de o ma, la p epa ación de cin as me álicas,
a amien os é micos, p oducción de pol o y la ans o mación de es os
ma e iales en in as imp imibles, culminando en la ab icación adi i a de
es uc u as 3D complejas con p opiedades magne ocaló icas conse adas en
cada paso.
La esis comienza con una in oducción exhaus i a de los e ec os caló icos, con
un en oque en el e ec o magne ocaló ico. El e ec o magne ocaló ico,
ca ac e izado po cambios de empe a u a en espues a a a iaciones en el
campo magné ico, ep esen a una ía al e na i a pa a soluciones de
en iamien o sos enible y ges ión é mica e icien e en ene gía. En e los
ma e iales exis en es que mues an el e ec o magne ocaló ico, la esis se cen a
en una amilia de ma e iales llamada aleaciones magné icas de memo ia de
o ma Heusle , especí icamen e en aquellas basadas en combinaciones de
Níquel y Manganeso con o os elemen os.
El p ime paso de la esis es p opo ciona una isión gene al comple a de los
ma e iales magne ocaló icos del ipo Heusle , con un en oque en sus
p opiedades es uc u ales y magné icas. Es a sección incluye una explo ación
de allada del e ec o magne ocaló ico, las ansiciones de ase y los p incipios
subyacen es de es os ma e iales. El es udio p o undiza en la inco po ación de
cie os elemen os en los sis emas de aleaciones, elucidando su impac o
IV
p o undo en las p opiedades de las aleaciones Heusle y la mejo a del e ec o
magne ocaló ico. El abajo se cen a en log a composiciones de aleación
óp imas que equilib en la e iciencia y las conside aciones ambien ales.
La in es igación pasa de la explo ación eó ica basada en la in es igación de la
li e a u a a la implemen ación p ác ica a medida que se ab ican múl iples
aleaciones magne ocaló icas de Heusle median e di e en es écnicas.
Empleando la écnica de mel -spinning, las aleaciones se ans o man en cin as
me álicas, allanando el camino pa a la op imización pos e io a a és de
a amien os é micos es a égicamen e diseñados. Se ealiza un es udio
sis emá ico de los a amien os é micos pa a a ina las p opiedades magné icas
y magne ocaló icas de las cin as, con el in de log a las p opiedades óp imas.
Un a ance inno ado en la esis gi a en o no a la ans o mación de las cin as
en in as imp imibles pa a su pos e io implemen ación en imp esión 2D y 3D.
A a és de molienda mecánica, las cin as se con ie en en pol o, al cual se le
ealizan a amien os é micos pa a con a es a los e ec os de la deg adación
del ma e ial inducida po la molienda. Es e pol o más adelan e se mezcla con
di e sos políme os biodeg adables, en e ellos celulosa, que es un políme o
espe uoso con el medio ambien e y con mucha biodisponibilidad, pa a c ea
in as imp imibles pa a aplicaciones de ab icación adi i a, inaugu ando la
capacidad de elabo a es uc u as 3D, p ese ando las p opiedades
magne ocaló icas de las cin as.
Pa a desa olla an o la écnica de imp esión 2D, median e se ig a ía, como la
de 3D, median e el p oceso llamado imp esión po ex usión, p ime amen e, se
emplea on pol os me álicos come ciales (Hie o, Aluminio, Silicio) sin ninguna
uncionalidad, dado que es os pol os son económicos y áciles de ob ene . De
es a o ma se ab ió la pue a a, p ime amen e, desa olla la u a de c eación y
op imización de in as imp imibles y, después, a encon a las limi aciones de
V
las écnicas de imp esión, y encon a las es uc u as que e an imp imibles y
encon a las limi aciones que cada écnica de imp esión enía.
Una ez encon ados los pa áme os que op imizaban los p ocesos de
imp esión se implemen ó a los pol os magne ocaló icos pa a así ob ene ilms
2D y es uc u as 3D magne ocaló icas de di e sas o mas y amaños.
La p ime a alidación de las in as magne ocaló icas se ealizó median e
imp esión 2D po se ig a ía. Las p imeas p uebas de imp esión se ealizan
imp imiendo igu as geomé icas muy simples de una sola capa y
pos e io men e se aplican múl iples capas pa a aumen a así la can idad de
ma e ial uncional que con iene el ilm imp eso. Debido a la na u aleza de la
celulosa, se ob u ie on ilms lexibles con un al o con enido en ma e ial
magne ocaló ico, que pod ían se i pa a aplicaciones en disposi i os de
elec ónica. Además, es os ilms imp esos p ese an las p opiedades
magne ocaló icas del ma e ial uncional p ecu so , quedando así alidad la
écnica de imp esión 2D pa a ma e iales magne ocaló icos ( e Figu a 1).
Figu e 1: Esquema del p oceso de imp esión 2D po se ig a ía. Las p opiedades magne ocaló icas del ilm lexible
imp eso son análogas a las de las cin as, que cons i uyen el ma e ial p ecu so .
XII

XIII
Abs ac
In he ques o sus ainable and ene gy-e icien cooling and e ige a ion
echnologies, he s udy o calo ic e ec s has eme ged as a p omising a enue.
This doc o al hesis emba ks on an ex ensi e explo a ion o he magne ocalo ic
e ec , wi h a p ima y goal o enabling he cos -e ec i e 2D – 3D p in ing o
magne ocalo ic s uc u es using en i onmen ally- iendly ma e ials. The
esea ch encompasses he syn hesis o Heusle magne ic shape memo y alloys,
ibbon p epa a ion, hea ea men s, powde p oduc ion, and he
ans o ma ion o hese ma e ials in o p in able inks, culmina ing in he addi i e
manu ac u ing o complex 2D – 3D s uc u es wi h e ained magne ocalo ic
p ope ies a each s ep.
An in-dep h explo a ion in o he magne ocalo ic e ec inhe en in Heusle
magne ic shape memo y alloys, wi h a p ima y ocus on elucida ing he po en ial
echnological applica ions o his calo ic phenomenon is s udied. The
in oduc o y discou se p o ides a ho ough examina ion o calo ic e ec s, wi h
speci ic a en ion di ec ed owa ds he magne ocalo ic e ec and i s ele ance
in di e se echnological domains.
The esea ch igo ously in es iga es he o -s oichiome ic NiMn-X (X=Sn,
In,Ga) Heusle alloys, elucida ing he nuanced impac o he inco po a ion o
dopan elemen s such as Cobal , Coppe and I on on hei ans o ma ion,
magne ic and magne ocalo ic p ope ies. Employing he mel -spinning
echnique, ibbons a e ab ica ed and subjec ed o a sys ema ic hea ea men
p o ocols designed o op imize hei ans o ma ion, magne ic and
magne ocalo ic p ope ies.
A ou e o powde p epa a ion om he ibbons is s udied and es ablished.
This powde unde goes a e ined hea ea men p ocedu e o mi iga e he
XIV
de imen al e ec s o g inding, ensu ing he p ese a ion o magne ocalo ic
p ope ies du ing his ma e ial p ocessing.
Cha ac e iza ion o bo h ibbons and powde se es as he ounda ional
g oundwo k o he subsequen explo a ion o addi i e manu ac u ing
applica ions. Fo mula ion o p in able inks u ilizing cellulose as a polyme
acili a es he c ea ion o no el 2D-3D s uc u es h ough addi i e
manu ac u ing echniques.
Following he p in ing p ocess, he ab ica ed s uc u es unde go a me iculous
hea ea men egime, in ol ing calcina ion o emo e he polyme and
sin e ing o achie e s uc u al compac ness and mechanical in eg i y. Va ious
sin e ing ou es a e sys ema ically in es iga ed o disce n he op imal app oach
ha balances mechanical obus ness wi h he p ese a ion o magne ocalo ic
e ec s h oughou each s age.
The o e a ching objec i e o his esea ch is o demons a e he sus ained
e en ion o magne ocalo ic p ope ies ac oss he en i e spec um o p ocesses,
om alloy ab ica ion o mel -spinning, hea ea men o g inding, addi i e
manu ac u ing o sin e ing and ge ing 100% magne ocalo ic 3D s uc u e. The
indings no only con ibu e nuanced insigh s in o he manipula ion o Heusle
alloys o p ac ical applica ions bu also pa e he way o he de elopmen o
ad anced ma e ials wi h enhanced magne ocalo ic unc ionali ies in he sec o
o addi i e manu ac u ing.
XV
Visual Abs ac
XVI
XVII
Con en s
Ag adecimien os I
Resumen III
Labu pena IX
Abs ac XIII
Visual Abs ac XV
1. Chap e 1: In oduc ion............................................................................1
1.1. Mo i a ion.....................................................................................................3
1.2. Calo ic Ma e ials.........................................................................................4
1.2.1. Magne ocalo ic e ec ..........................................................................5
1.2.1.1. Con en ional magne ocalo ic e ec ......................................8
1.2.1.2. In e se magne ocalo ic e ec ................................................13
1.2.1.3. Re ige a ion capaci y.............................................................13
1.2.2. Elas ocalo ic e ec .............................................................................15
1.3. Ma ensi ic ans o ma ion and shape memo y e ec ..............16
1.4. Heusle - ype NiMn-based magne ic shape memo y alloys
(MMMAs)...............................................................................................20
1.4.1. NiMn-based Heusle alloys...............................................................22
1.4.1.1. E ec s o doping.....................................................................25
(a) Co addi ion....................................................................................25
(b) Cu addi ion....................................................................................27
1.4.1.2. E ec o ab ica ion me hods...............................................28
1.4.1.3. Hea ea men s.......................................................................29
1.5. Applied aspec s o magne ocalo ic ma e ials..........................31
1.5.1. Ac i e Magne ic egene a o s............................................................31
1.5.2. Magne ic e ige a o ..........................................................................32
1.6. Addi i e Manu ac u ing.................................................................34
1.6.1. Sc een-p in ing....................................................................................35
1.6.2. Cold ex usion p in ing......................................................................36
1.7. S a e o he a ....................................................................................37
1.8. Objec i es ..........................................................................................38
1.9. Re e ences..........................................................................................39

XVIII
2. Chap e 2: Expe imen al Me hods....................................................47
2.1. Choosing alloy composi ion.........................................................49
2.2. Alloys Fab ica ion............................................................................49
2.2.1. Induc ion cas ing................................................................................49
2.2.2. A c-mel ing..........................................................................................50
2.3. Mel -Spinning...................................................................................51
2.4. Powde P epa a ion.........................................................................52
2.4.1. Manual g inding..................................................................................52
2.4.2. Hamme milling..................................................................................52
2.4.3. Gas a omiza ion.................................................................................53
2.5. Hea T ea men s..............................................................................53
2.6. Ink P epa a ion.................................................................................54
2.6.1. Collagen-based ink..............................................................................54
2.6.2. Silk-based ink.......................................................................................55
2.6.3. Cellulose-based ink.............................................................................56
2.7. 2D P in ing ........................................................................................57
2.7.1. Doc o Blade.......................................................................................57
2.7.2. Sc een-p in ing....................................................................................57
2.8. 3D P in ing ........................................................................................58
2.9. Cha ac e iza ion Me hods.............................................................59
2.9.1. Vib a ing Sample Magne ome e (VSM).........................................59
2.9.2. Supe conduc ing Quan um In e e ence De ice (SQUID)..........60
2.9.3. Di e en ial Scanning Calo ime y (DSC.........................................60
2.9.4. Scanning Elec on Mic oscopy (SEM).............................................61
2.9.5. Magne ic ield-induced adiaba ic empe a u e change...................61
2.9.6. Mechanical cha ac e iza ion..............................................................62
2.9.7. X-Ray Di ac ion...............................................................................62
2.9.8. Magne ic ield induced en opy change calcula ion.......................63
2.10. Re e ences..........................................................................................64
3. Chap e 3: Sea ch o NiMn-Based MSMAs in Ribbon Fo m
wi h Po en ially Enhanced MCE Pe o mance..........................65
3.1. In oduc ion ......................................................................................67
3.2. NiMnSn MSMA Sys em.................................................................69
3.2.1. Mn42.5Ni40Co8Sn9.5...............................................................................69
3.2.1.1. Composi ion and mic os uc u e..........................................69
3.2.1.2. T ans o ma ion cha ac e is ics..............................................70
XIX
3.2.2. Mn48Ni35.5Sn8Co6.5Fe2 .........................................................................72
3.2.2.1. Composi ion and mic os uc u e..........................................72
3.2.2.2. T ans o ma ion cha ac e is ics..............................................73
3.2.2.3. “Magne ic ield – empe a u e” phase diag ams o
ma ensi ic ans o ma ion......................................................................74
3.2.2.4. Magne ic ield induced en opy change................................75
3.2.2.5. Re ige an capaci y.................................................................76
3.2.2.6. Adiaba ic magne ocalo ic e ec ............................................77
3.2.3. Ni43Mn39Co7Sn11 .................................................................................79
3.2.3.1. Composi ion analysis..............................................................79
3.2.3.2. T ans o ma ion cha ac e is ics..............................................79
3.3. NiMnGa MSMA Sys em................................................................81
3.3.1. Ni49Mn20Cu6Ga23Fe2...........................................................................81
3.3.1.1. Composi ion and mic os uc u e..........................................81
3.3.1.2. T ans o ma ion cha ac e is ics..............................................82
3.3.2. Ni46Mn30Co5Ga20 ................................................................................83
3.3.2.1. Composi ion and mic os uc u e..........................................83
3.3.2.2. T ans o ma ion cha ac e is ics..............................................83
3.3.3. Ni46Mn31Co5Ga17Fe1...........................................................................85
3.3.3.1. Composi ion and mic os uc u e..........................................85
3.3.3.2. T ans o ma ion cha ac e is ics..............................................86
3.3.4. Ni50Mn18.7Cu6.25Ga25 ...........................................................................87
3.3.4.1. Composi ion and mic os uc u e..........................................87
3.3.4.2. T ans o ma ion cha ac e is ics..............................................88
3.3.5. Ni50Mn18Cu5Ga25Fe2...........................................................................89
3.3.5.1. Composi ion analysis..............................................................89
3.3.5.2. T ans o ma ion cha ac e is ics..............................................89
3.4. NiMnIn MSMA Sys em.................................................................90
3.4.1. Ni45.2Mn36.7Co5.1In13.0..........................................................................90
3.4.1.1. Composi ion analysis..............................................................90
3.4.1.2. T ans o ma ion cha ac e is ics..............................................91
3.5. Conclusions.......................................................................................92
3.6. Re e ences..........................................................................................93
4. Chap e 4: P oduc ion and In es iga ion o NiMn-Based
MSMAs Powde s wi h Enhanced MCE P ope ies..................95
4.1. Powde p oduc ion om ibbons and by gas a omiza ion...97
4.2. NiMnSn MSMA Sys em.................................................................99
XX
4.2.1. Mn42.5Ni40Co8Sn9.5...............................................................................99
4.2.1.1. Composi ion and mic os uc u e..........................................99
4.2.1.2. X- ay di ac ion......................................................................99
4.2.1.3. T ans o ma ion cha ac e is ics............................................102
4.2.2. Mn48Ni35.5Sn8Co6.5Fe2.......................................................................103
4.2.2.1. T ans o ma ion cha ac e is ics............................................103
4.2.3. Ni43Mn39Co7Sn11 ...............................................................................104
4.2.3.1. Composi ion and mic os uc u e........................................104
4.2.3.2. T ans o ma ion cha ac e is ics............................................105
4.2.3.3. “Magne ic ield – empe a u e” phase diag ams o
ma ensi ic ans o ma ion...................................................................107
4.2.3.4. Magne ocalo ic e ec ...........................................................110
4.2.3.4.1. Magne ic ield-induced en opy change.................110
4.2.3.4.2. Re ige a ion capaci y...............................................112
4.2.4. Ni49.8Mn36.6Sn13.6 ..............................................................................113
4.2.4.1. Composi ion and mic os uc u e........................................113
4.2.4.2. T ans o ma ion cha ac e is ics............................................114
4.2.4.3. “Magne ic ield – empe a u e” phase diag ams o
ma ensi ic ans o ma ion...................................................................114
4.2.4.4. Magne ocalo ic e ec ...........................................................115
4.2.4.4.1. Magne ic ield-induced en opy change.................115
4.3. NiMnGa MSMA Sys em..............................................................117
4.3.1. Ni50Mn18.7Cu6.25Ga25........................................................................117
4.3.1.1. Composi ion and mic os uc u e........................................117
4.3.1.2. T ans o ma ion cha ac e is ics............................................117
4.4. Conclusions.....................................................................................118
4.5. Re e ences........................................................................................119
5. Chap e 5: Design and Fab ica ion o No el Me allic
P in able Ma e ials...................................................................................121
5.1. 2D and 3D p in ing o comme cial powde s..........................123
5.1.1. Technique alida ion........................................................................123
5.1.2. Sea ching o a binde and sol en s o eco- iendly app oach
using me allic powde as ille ..............................................................124
5.1.2.1. Silk-based ink.........................................................................124
5.1.2.2. Collagen-based ink................................................................124
5.1.2.3. Cellulose-based ink...............................................................124
5.1.3. Comme cial powde s and ink pa ame e s....................................125
XXI
5.1.4. P in ing comme cial powde s.........................................................127
5.1.4.1. Sc een-p in ing......................................................................127
5.1.4.2. Cold-ex usion p in ing.......................................................129
5.1.4.2.1. I on (Fe) ink...............................................................130
5.1.4.2.2. Aluminium (Al) ink...................................................132
5.1.4.2.3. Silicon (Si) ink.............................................................133
5.1.5. Hea ea men s: Calcina ion and sin e ing...................................134
5.1.6. Nickel elec odeposi ion..................................................................136
5.1.7. SEM cha ac e iza ion: Composi ion opog aphy.........................137
5.1.8. Mechanical cha ac e iza ion............................................................141
5.2. 2D And 3D P in ing o Magne ocalo ic Heusle -Type
MSMAs.........................................................................................................142
5.2.1. Silk-based MCE ink......................................................................142
5.2.1.1. Ink p epa a ion and p in ing es s.......................................142
5.2.1.2. T ans o ma ion cha ac e is ics and magne ocalo ic
e ec ........................................................................................................143
5.2.2. Cellulose-based MCE inks..........................................................144
5.2.2.1. Ink pa ame e s.......................................................................144
5.2.3. Sc een-p in ing o Mn42.5Ni40Co8Sn9.5 magne ocalo ic ink.145
5.2.3.1. P in ing es s..........................................................................145
5.2.3.2. Magne ic aniso opy in p in ed samples.............................146
5.2.3.3. “Magne ic ield – empe a u e” phase diag ams o
ma ensi ic ans o ma ion...................................................................147
5.2.3.4. Magne ocalo ic e ec ...........................................................149
5.2.3.4.1. Magne ic ield induced en opy change..................149
5.2.3.4.2. Adiaba ic magne ocalo ic e ec ..............................152
5.2.4. 3D cold-ex usion p in ing o magne ocalo ic inks.............153
5.2.4.1. Mn42.5Ni40Co8Sn9.5...............................................................153
5.2.4.1.1. P in ing.......................................................................153
5.2.4.1.2. Mic os uc u e and composi ion analysis..............154
5.2.4.1.3. Calcina ion and sin e ing: T ans o ma ion
cha ac e is ics....................................................................................155
5.2.4.1.4. Magne ocalo ic e ec ................................................157
5.2.4.2. Ni49.8Mn36.6Sn13.6...................................................................159
5.2.4.2.1. P in ing es s...............................................................159
5.2.4.2.2. Calcina ion and sin e ing..........................................160
5.2.4.2.3. Mic os uc u e analysis.............................................160
5.2.4.2.4. T ans o ma ion cha ac e is ics................................161
6
In oduc ion
la e in 1878[9]. Thomson deduced ha i on would wa m up when a magne ic
ield was applied o i and cool down when he ield was emo ed. While some
li e a u e claims ha E. Wa bu g was i s who has obse ed he MCE in i on
in 1881[10][11], he phenomenon was explici ly demons a ed only in 1917 by
Weiss and Picca d. They measu ed Ni a ound i s Cu ie empe a u e a 1.5T and
ound a empe a u e change o 0.7 K[11]. In 1933, Giauque and MacDougall
achie ed sub Kel in empe a u e o 0.25 K using a demagne iza ion o he
pa amagne ic Gd2(SO4)3 × 8H2O sal cooled by liquid helium om 1.5 K [12].
Th ee decades la e , in 1967, B own cons uc ed a ecip oca ing magne ic
e ige a o o demons a e he easibili y o oom- empe a u e magne ic
e ige a ion using Gd me al[13], achie ing a empe a u e span o 47 K a e 50
cycles.
A e his pe iod, MCE was no ex ensi ely in es iga ed un il 3 decades
la e when Pecha sky and Gschneide disco e ed he gian magne ocalo ic
e ec (GMCE) in Gd5Si2Ge2 in 1977[7]. Fo his alloy, he MCE was enhanced
due o a s uc u al ans o ma ion ha comes wi h he magne ic ansi ion.
Following his disco e y, he numbe o publica ions on he magne ocalo ic
e ec and magne ic e ige a ion was s eadily inc easing wi h some ecen
s abiliza ion end (Figu e 1.1).
Figu e 1.1: Publica ions abou magne ocalo ic e ec o e pas decades (SCOPUS).

7
Chap e 1
Enhanced p ope ies o magne ocalo ic ma e ials achie ed o e he las
decades ha e inc eased he in e es in using hem o solid-s a e e ige a ion
ins ead o a gas-expansion-comp ession echnology o a con en ional e ige a ion.
The eplacemen o adi ional echnology by solid s a e e ige a ion,
pa icula ly, by MCE cooling, o e s se e al ad an ages:
❖ En i onmen ally- iendliness since i does no use ozone-deple ing gases
like (CFC’s, HCFC’s)
❖ Highe e iciency (60% o Ca no e iciency compa ed o 40% o
con en ional e ige a ion), equi ing less ene gy and esul ing in educed
CO2 emissions
❖ Lowe cos s
❖ Minimal main enance and educed noise
Figu e 1.2: Visualiza ion o magne ocalo ic cooling in a single cycle e sus i s analogue o he apou
comp ession sys em.
Figu e 1.2 illus a es he undamen al wo king mechanism o magne ic
e ige a ion in compa ison o i s apou expansion-comp ession e ige a o
coun e pa . In he case o con en ional e ige a ion, a gas unde goes adiaba ic
comp ession and decomp ession, esul ing in hea gene a ion du ing
8
In oduc ion
comp essing and hea dissipa ion du ing adiaba ic decomp ession. Analogously,
in solid-s a e e ige a ion, he cycle s a s wi h he ma e ial a he mal
equilib ium, wi h magne ic momen s andomly o ien ed.When a magne ic ield
is applied unde an adiaba ic condi ions, he magne ic dipoles align wi h he
magne ic ield, causing he sample o expe ience a empe a u e inc ease due o
a dec ease in i s magne ic en opy. A e he inc eased hea dissipa es h ough
a adia o , he ma e ial e u ns o i s ini ial empe a u e. When he magne ic
ield is emo ed adiaba ically, he ma e ial expe iences a empe a u e dec ease,
eaching a lowe empe a u e han he ini ial one. This s age can be used o
e ige a ion. A e his, he ma e ial he mally s abilizes and he cycle s a s
again.
Bo h con en ional and in e se magne ocalo ic e ec s a e cha ac e ized by
he iso he mal en opy change, ΔSm(T, H), and/o he adiaba ic empe a u e
change, ΔTad(T, H), when a magne ic ield is applied o emo ed unde
iso he mal o adiaba ic condi ions, espec i ely[14][15]. In he mos easies way,
he magne ic ield induced en opy change can be es ima ed using a
he modynamic Maxwell ela ionship[16], al hough in he case o he i s -o de
magne os uc u al ans o ma ions some addi ional conside a ions should be
aken in o accoun [16][17]. Commonly, he momagne ic cu es measu ed
unde he iso- ield condi ions a e used o calcula e ΔSm(T, H) h ough
nume ical app oxima ion o he Maxwell ela ionship:
∆𝑆𝑚(𝑇,𝐻)= 𝑆𝑚(𝑇,𝐻)−𝑆𝑚(𝑇,0)=∫(𝜕𝑀(𝑇,𝐻′)
𝜕𝑇 )𝑑𝐻′
𝐻
0 (3)
1.2.1.1. Con en ional magne ocalo ic e ec
In e ms o ene gy, he magne ocalo ic e ec is cha ac e ized as he
change o magne ic en opy in an iso he mal p ocess o as he change o
empe a u e unde adiaba ic condi ions upon he applica ions o an ex e nal
magne ic ield (∆𝐻). The physical p ocess o he MCE is ela ed o he coupling
9
Chap e 1
be ween he ex e nal magne ic ield and he magne ic momen s wi hin he
ma e ial. Fi s , we will explain he MCE mechanism wi h a pic o ial desc ip ion
and hen we will p o ide a mo e o mal he modynamic in e p e a ion.
Le us assume a magne ic ma e ial is inside and ou side a magne ic ield
(see Figu e 1.3). When no magne ic ield is applied, he magne ic momen s a e
andomly o ien ed, gi ing ise o some en opy, which we will e e o as
magne ic en opy, SM. I we adiaba ically apply a magne ic ield o he ma e ial
(Fig 1.3 le ), he magne ic momen s will become o ien ed wi h he ield (le us
assume ully o ien ed, o simplici y) and he magne ic en opy becomes ze o
(SM = 0), esul ing in a nega i e change in magne ic en opy (SM < 0). Since he
p ocess is adiaba ic, he o al en opy change is ze o (∆S = 0). The o al en opy
change includes la ice (SL), elec onic (SE) and magne ic (SM) con ibu ions so:
∆𝑆=∆𝑆𝐿+∆𝑆𝑀+∆𝑆𝐸=0⇒∆𝑆𝐿+∆𝑆𝐸=−∆𝑆𝑀>0 (4)
This posi i e change in elec on and la ice en opy implies an inc ease in
empe a u e o he ma e ial. When he magne ic ield is adiaba ically emo ed,
he magne ic momen s becomes diso ien ed, esul ing in he cooling o he
ma e ial. Fo MCE measu emen , he adiaba ic empe a u e change (∆𝑇𝑎𝑑)
achie ed in his p ocess o magne iza ion/demagne iza ion is used as a
pa ame e o e alua e he ma e ial’s cooling e iciency.
Figu e 1.3: Schema ic ep esen a ion o applica ion o an ex e nal magne ic ield unde adiaba ic (le ) and
iso he mal ( igh ) condi ions.
10
In oduc ion
Apa om he adiaba ic empe a u e change, he MCE can also be
ep esen ed by he iso he mal en opy change, ∆𝑆𝑖𝑠𝑜. Figu e 1.3 igh shows he
magne iza ion p ocess unde iso he mal condi ions. In his case, magne ic
en opy eaches ze o a e he alignmen o he magne ic momen s wi h he
magne ic ield, so he magne ic en opy change is nega i e (∆𝑆𝑀<0). This
magne ic en opy, associa ed wi h magne ic momen s, is “ eleased” o he
en i onmen because he empe a u e emains cons an , making i equals o
∆𝑆𝑖𝑠𝑜 (assuming he e is no coupling be ween he h ee con ibu ions o en opy
s a ed abo e). Unlike adiaba ic empe a u e change, ∆𝑆𝑖𝑠𝑜 is ela i ely easy o
measu e and is he mos commonly epo ed pa ame e in MCE e alua ions.
F om hese conside a ions, we can deduce ha he la ges en opy change
and hus he la ges adiaba ic empe a u e change will be ob ained when
magne ic momen s become ully diso ien ed a 𝐻=0 and ully aligned a 𝐻≠
0. The ma e ials ha can sa is y hese condi ions a ambien empe a u es and
achie able magne ic ields in p ac ice a e e omagne s. Fo hese ma e ials, he
magne ic momen s na u ally align hemsel es a he Cu ie empe a u e and
e omagne ic o de ing can be achie ed unde ela i ely small magne ic ields.
In he case o pa amagne s, spon aneous e omagne ic o de ing does no occu
and la ge magne ic ields a e equi ed o induce such o de , making
e omagne s he only ones o p ac ical in e es .
Figu e 1.4: En opy e sus empe a u e beha iou o a magne ic ma e ial unde no magne ic ield and unde
a magne ic ield o a i s -o de magne ic o de ing (le ) and a second-o de magne ic o de ing ( igh ).
11
Chap e 1
The magne ic en opy change depends on bo h magne ic ield and
empe a u e. The empe a u e e olu ion a wo di e en magne ic ields is
g aphically depic ed in Figu e 1.4, whe e we can dis inguish wo p ocesses:
❖ Iso he mal magne iza ion change ( e ical line). The magne ic ield is
applied iso he mally, educing he en opy by ∆𝑆𝑖𝑠𝑜, while la ice and
elec onic con ibu ions emain cons an . Magne ic en opy change is
gi en by:
∆𝑆𝑀(𝑇)𝑇,∆𝐻,𝑃 =[𝑆𝑀(𝑇)𝐻1−𝑆𝑀(𝑇)𝐻0]𝑇,𝑃 =[𝑆1(𝑇)𝐻1−𝑆0(𝑇)𝐻0]𝑇,𝑃 (5),
whe e 𝑆𝑀 is he magne ic en opy and 𝑆0,𝑆1 a e he o al en opies a
di e en magne ic ields.
❖ Adiaba ic magne iza ion change (ho izon al line): Applying he magne ic
ield unde adiaba ic condi ions leads o he o de ing o magne ic
momen s. The magne ic en opy dec eases whe eas he elec onic and
la ice en opies inc ease o main ain he o al en opy cons an . This
esul s in an inc ease o he empe a u e in he ma e ial by a alue ∆𝑇𝑎𝑑,
exp essed as: ∆𝑇𝑎𝑑(𝑇)𝑇,∆𝐻,𝑃 =[𝑇1(𝑆)𝐻1−𝑇0(𝑆)𝐻0]𝑆,𝑃 (6),
whe e 𝑇0 and 𝑇1 a e he empe a u es in magne ic ields 𝐻0 and 𝐻1,
espec i ely.
The magne ocalo ic e ec can be ea ed om a mo e o mal
he modynamic app oach. The en opy, which is he i s de i a i e o he
Gibbs ee ene gy (𝑆=−(𝜕𝐺/𝜕𝑇)𝑃), is a con inuous unc ion o empe a u e
bu changes i s slope a he ansi ion empe a u e. While en opy canno be
measu ed di ec ly, i can be calcula ed om an expe imen ally measu able
quan i y, namely, he hea capaci y, 𝐶(𝑇)𝐻,𝑃:
𝑆(𝑇)𝐻,𝑃 =∫𝐶(𝑇)𝐻,𝑃
𝑇𝑑𝑇
𝑇
0 (7)

12
In oduc ion
The o al en opy o he ma e ial as a unc ion o empe a u e is shown in
Figu e 1.4 le o a i s -o de magne ic ansi ion. In his case, he e is a
discon inuous change o en opy a ansi ion empe a u e T1. The jump in he
en opy comes om he en halpy o he ansi ion, ∆𝐸, and he en opy inc ease
is ∆𝐸/𝑇. The iso he mal en opy change a empe a u e T (𝑇𝑡1 <𝑇<𝑇𝑡2) is:
∆𝑆𝑖𝑠𝑜(𝑇)∆𝐻,𝑃 =∫𝐶𝑙(𝑇)𝐻2,𝑃
𝑇𝑑𝑇
𝑇
0−∫𝐶𝑙(𝑇)𝐻1,𝑃
𝑇𝑑𝑇
𝑇𝑡1
0−∫𝐶ℎ(𝑇)𝐻1,𝑃
𝑇𝑑𝑇
𝑇
𝑇𝑡1
−∆𝐸𝐻1
𝑇𝑡1 (8)
whe e 𝐶𝑙 and 𝐶ℎ a e he hea capaci ies a low- (below ansi ion empe a u e)
and high- empe a u e (abo e ansi ion empe a u e) phases. I we assume ha
𝐶𝑙(𝑇)𝐻,𝑃 ≈𝐶ℎ(𝑇)𝐻,𝑃 as obse ed in Gd5Si2Ge2 o he same magne ic
ield[18], we ge :
∆𝑆𝑖𝑠𝑜(𝑇)∆𝐻,𝑃 =∫𝐶(𝑇)𝐻2,𝑃 −𝐶(𝑇)𝐻1,𝑃
𝑇𝑑𝑇
𝑇
0−∆𝐸𝐻1
𝑇1 (9)
F om his equa ion i can be deduced ha he la ge di e ence be ween
he hea capaci ies in wo ields gi es a la ge en opy change. The las e m in
his equa ion, called he s uc u al en opy change, ∆𝑆𝑠𝑡𝑟, is an addi ional
con ibu ion associa ed wi h he i s -o de phase ansi ion and he ab up
a omic ea angemen ha happens in his class o ansi ions. The ela ion
be ween he en opy change and he adiaba ic empe a u e change is gi en
by[15]:
∆𝑇𝑎𝑑(𝑇)∆𝐻,𝑃 ≅ − 𝑇
𝐶(𝑇0)𝐻2,𝑃∆𝑆𝑖𝑠𝑜(𝑇)∆𝐻,𝑃 (10)
whe e 𝑇0∈[ 𝑇,𝑇+∆𝑇𝑎𝑑(𝑇)∆𝐻,𝑃 ] and is unknown. In any case, om he abo e
equa ion we see ha ∆𝑇𝑎𝑑 is di ec ly p opo ional o en opy change and
in e sely p opo ional o he hea capaci y, so i will be lowe o ma e ials wi h
a high hea capaci y.
13
Chap e 1
When he ma e ial unde goes a second-o de magne ic ansi ion (Figu e
1.4 igh ), he en opy is a con inuous unc ion o empe a u e and changes i s
slope a he ansi ion empe a u e. In his case, he iso he mal en opy change
is gi en by:
∆𝑆𝑖𝑠𝑜(𝑇)∆𝐻,𝑃 =∫𝐶(𝑇)𝐻2,𝑃 −𝐶(𝑇)𝐻1,𝑃
𝑇𝑑𝑇
𝑇
0 (11)
F om his equa ion, we can see ha he en opy change will be la ge when
he di e ence be ween he hea capaci ies in wo ields is la ge. The exp ession
o he en opy change, Eqs.(9,11), a e he heo e ical ones. In eali y, only 60-
90% o his can be achie ed. Mo eo e , only a small ac ion o his en opy
(less han 30%) is used in a magne ocalo ic p ocess, so expe imen al alues o
∆𝑆𝑚𝑎𝑔 a e signi ican ly smalle han he heo e ical ones.
1.2.1.2. In e se magne ocalo ic e ec
The in e se magne ocalo ic e ec is he opposi e phenomenon o he
con en ional one. In his case, he magne ic en opy change is posi i e when
he adiaba ic empe a u e change is nega i e, and ice e sa. The sample cools
down when a magne ic ield is applied. This e ec is ound in ma e ials ha
unde go a e e se ma ensi ic ans o ma ion, om
pa amagne ic/an i e omagne ic ma ensi e o e omagne ic aus eni e. I is
obse ed in NiMnX (X=Sn, In, Sb) Heusle - ype alloys and has been
ex ensi ely s udied[19][20][21].
1.2.1.3. Re ige a ion capaci y
MCE is also cha ac e ized by a e ige an capaci y (RC) which is de ined
as he amoun o hea ans e ed be ween ho and cold ese oi s in a single
e ige a ion cycle. The e a e h ee di e en ways o calcula ing he RC, as
epo ed in li e a u e:
14
In oduc ion
(1) Rela i e cooling powe (RCP), de e mined by he p oduc |∆𝑆𝑀( 𝐻)|𝑚𝑎𝑥 ×
𝛿𝑇𝐹𝑊𝐻𝑀(𝐻) [19]
(2) In oduced by Gschneidne , whe e he a ea unde he peak o ∆𝑆𝑀 wi hin
𝛿𝑇𝐹𝑊𝐻𝑀 empe a u e ange is calcula ed[22]:
𝑅𝐶=∫|∆𝑆𝑀(𝑇,𝐻)|𝑑𝑇
𝑇ℎ𝑜𝑡
𝑇𝑐𝑜𝑙𝑑 (12)
(3) By Wood and Po e , whe e he a ea o he la ges ec angle o ∆𝑆𝑀 is
es ima ed[23]
Figu e 1.5: Schema ic ep esen a ion o he RC ob ained om he magne ic en opy change cu e. The RCP
blue ec angle has he same wid h as he Gschneidne a ea’s maximum wid h.
These h ee calcula ions a e shown g aphically in Figu e 1.5. Since bo h
he en opy change and adiaba ic empe a u e change a e p opo ional o he
de i a i e o magne iza ion wi h espec o empe a u e, |𝜕𝑀/𝜕𝑇|, he g ea e
is he a ia ion o magne iza ion wi h empe a u e, he highe alues o MCE
a e achie ed. This is expec ed o bo h i s - and second-o de phase
ansi ions. The MCE occu s a he Cu ie empe a u e in second-o de phase
ansi ions, i.e., ansi ion om pa amagne ic o e omagne ic o de ing.
15
Chap e 1
1.2.2. Elas ocalo ic e ec
The elas ocalo ic e ec (eCE) is he he mal esponse o an ex e nal
mechanical s ess. This ex e nal s imulus induces a phase ans o ma ion,
esul ing in an en opy change and, consequen ly, a empe a u e change in he
ma e ial. Elas ocalo ic ma e ials epo ed o cooling mainly include NiTi-
based, Fe-based, Cu-based and e omagne ic SMAs. Rubbe , as an example,
inc eases i s empe a u e when apidly s e ched, as i s epo ed by Gough in
1805, who ound ou ha ubbe hea s sligh ly when s e ched apidly[24]. Soon
a e , Thomson p oposed a he modynamic in e p e a ion [25], and Joule
disco e ed se e al elas ocalo ic ma e ials[26]. Howe e , due o he weak calo ic
e ec s o common me als and polyme s, he elas ocalo ic e ec ba ely ecei ed
a en ion in he nex 100 yea s. In 1980, Rod iguez and B own, s udying he
ma ensi ic ans o ma ion, occasionally ound a signi ican eCE in
Cu69.6Al27.7Ni2.7 SMA [27]. In 2004, Qua ini and P ince epo ed la ge
empe a u e a ia ions o 16K and -14K in he NiTi alloy subjec ed o a loading-
holding-unloading p o ocol and o iginally p oposed he concep o solid-s a e
cooling[28].
As al eady men ioned, he elas ocalo ic e ec a ises om he abso p ion
o elease o la en hea du ing he ma ensi ic ans o ma ion ha occu s
du ing cyclic loading and unloading. Figu e 1.6 shows one cycle o loading and
unloading o a supe elas ic NiTi alloy. This B ay on cycle consis s o ou
s eps:
(i) Adiaba ic loading (1 → 2): in his s ep, an exo he mic ma ensi ic
ans o ma ion om highly-o de ed cubic aus eni ic phase o low-
symme y monoclinic ma ensi e phase occu s, esul ing in he
hea ing o he ma e ial.
(ii) Hea ing (2 → 3): The applied s ess o s ain is main ained a a
cons an alue while he ma e ial eleases he hea acqui ed in he i s
22
In oduc ion
1.4.1. NiMn-based Heusle alloys
Ni-Mn-based Heusle - ype Me aMagne ic Shape Memo y Alloys
(MMSMAs), a se o alloys ha p esen he Magne ocalo ic E ec (MCE), a e
o g ea in e es due o hei s ong po en ial o a solid-s a e e ige a ion. They
unde go a i s -o de ma ensi ic ans o ma ion om a high-symme y
e omagne ic aus eni ic phase a high empe a u e o a low-symme y weak
magne ic o an i e omagne ic ma ensi ic phase a lowe empe a u e, whe eby
exhibi ing a la ge change o he magne iza ion[37]. This magne os uc u al
ans o ma ion leads o he so-called magne ic shape memo y e ec [38]. In
addi ion, he applica ion o an ex e nal magne ic ield can shi he MT because
o he s ong magne os uc u al coupling[39][40][41], gi ing ise o he peculia
gian MCE phenomena, making hese ma e ials a p omising candida es o
e icien solid-s a e e ige a ion applica ions.
The phase s abili y as well as s uc u al and magne ic p ope ies o Ni-Mn-
X (X=In, Sn, Sb, Ga,…) Heusle alloys ha e been widely s udied bo h
heo e ically and expe imen ally in he li e a u e, showing ha i is possible o
manipula e, in he p edic able way, he magne ic exchange in e ac ions in bo h
low- empe a u e ma ensi e and high- empe a u e aus eni e, as well as une
o he mul i unc ional p ope ies, such as shape memo y e ec o
supe elas ici y, by he doping wi h many o he elemen s, such as Co, Cu, Fe,
Cd, W e c. [42][43][44][45][46][47][48]. Ni-Mn-based Heusle MMSMAs a e
e y a ac i e candida es o magne ocalo ic applica ions owing o he
a ailabili y o he aw ma e ials, non- oxici y, easiness- o-be-p epa ed and a
la ge magne ocalo ic e ec unde a magne ic ield o exis ing pe manen
magne s[49][50].
Ni-Mn-Sn Heusle alloys amily ep esen s one o he in ensi ely s udied
MMSMAs. This s oichiome ic compound, Ni2MnSn, has a L21 –o de ed cubic
s uc u e wi h ou in e pene a ing ace cen e ed cubic ( cc) subla ices[51]
(Figu e 1.10). In an ideal o de ed case, he (0,0,0) and (12
⁄ ,12
⁄ ,12
⁄ ) si es a e

23
Chap e 1
occupied by Ni a oms, lea ing he emaining (14
⁄ ,14
⁄ ,14
⁄ ) and (34
⁄ ,34
⁄ ,34
⁄ ) si es
being occupied by Sn and Mn a oms. On he o he hand, in o -s oichiome ic
Ni-Mn-Sn Heusle alloys, he excess o Mn a oms occupy he pa ially acan
Sn si es. Indeed, some pe cen age o Ni, Mn, Sn a oms may be dis ibu ed
andomly, o ming some deg ee o diso de p esen in he c ys al s uc u e
which can be la gely emo ed by annealing hese ma e ials a high
empe a u es[52][53].
Figu e 1.10: B2 s L21 s uc u es o aus eni ic phase.
Upon cooling om he mel , Ni-Mn-X (X= Sn, Sb, In, Ga) alloys
c ys allize i s in en i ely diso de ed A2 s uc u e, hen exhibi a pa ially
o de ed B2 s uc u e, whe e Ni a oms occupy he co ne posi ions and Mn and
Z a oms a e andomly loca ed in body-cen e ed (bcc) posi ions. Fu he cooling
p oduces he diso de -o de ansi ion whe e he c ys al s uc u e o alloys
ans o ms om B2 o L21, in which Ni a oms a e loca ed in he co ne s o he
s uc u e, whe eas Mn and Z a oms a e a al e na e body si es. The ma ensi e
ans o ma ion empe a u e depends on he a omic o de , which can be
modi ied by he chemical composi ion change and/o by he p ocessing o he
alloy.
The Ni-Mn-X alloys exhibi a ma ensi ic ans o ma ion in o ma ensi es
wi h a non-modula ed o modula ed c ys al la ices. When he concen a ion o
X a oms is low his amily o alloys ans o ms in o a non-modula ed e agonal
24
In oduc ion
L10 –o de ed ma ensi e [54]. Figu e 1.11 shows he c ys allog aphic la ice
ela ions be ween L21 aus eni e and L10 ma ensi e. Ma ensi e may ha e
modula ed s uc u es apa om L10 s uc u e (especially o alloys wi h a high
Z concen a ion). The mos common modula ed s uc u es a e he ollowing
ones:
(1) Fou -laye ed 4O s uc u es[55]
(2) Fi e-laye ed 10M s uc u e [56][57]
(3) Se en-laye ed 14M s uc u e[56]
These modula ed s uc u es a e o med by shea ing o he (110) planes
along he [11
0] c ys allog aphic di ec ion. The ab ica ion p ocess and chemical
composi ion signi ican ly in luence he c ys al s uc u e o ma ensi e and he
equilib ium ma ensi ic ans o ma ion empe a u e, Tm0.
The o -s oichiome ic Ni-de icien Ni-Mn-Sn Heusle alloys can be
doped wi h Cobal , whe e Cobal goes o he Ni si es. These Ni(Co)-Mn-Sn
Heusle alloys a e o g ea in e es since hey epo edly ha e MT nea oom
empe a u e[58]. P e ious wo ks ha e in es iga ed he c ys al s uc u es o
ma ensi e phases in hese alloys by means o X- ay di ac ion (XRD). Ume su
e al. showed ha Co-doped Ni-Mn-Sn alloy has an L21 s uc u e (Figu e 1.11)
a oom empe a u e[59], wi h space g oup Fm-3m (Cu2MnAl p o o ype). This
s uc u e is con i med in he p esen wo k using Mn- ich Ni40Mn42.5Co8Sn9.5
alloy a oom empe a u e [60]. Ume su e al. concluded ha in he Ni-Mn-Sn
alloy, he Mn momen s on 4a and 4b si es a e an i e omagne ically coupled,
whe eas in he Co-doped alloy hey a e e omagne ically coupled, a ibu ing
he e omagne ic enhancemen o he change in magne ic s uc u e by Co
subs i u ion.
On he o he hand, mel -spinning is a use ul echnique o ob aining
eady-shaped magne ocalo ic ma e ials wi h a high su ace/ olume a io
sui able o hei implemen a ion in ac i e magne ic egene a o s. Thanks o he
25
Chap e 1
high cooling a e o mel -spinning (abou 106 K/s) i can modi y he physical
cha ac e is ics o he alloys. Such high a es induce he s abiliza ion o he high
empe a u e aus eni e phase in Heule - ype MMSMAs wi h i s co esponding
B2 o de ed s uc u e ins ead o he highly o de ed L21 s uc u e. As a as MCE
and o he unc ionali ies o Ni-Mn-based Heusle alloys a e closely ela ed o
he c ys al s uc u es o cons i uen phases, a deep unde s anding o c ys al
s uc u e is equi ed o exploi ing all hese unc ionali ies owa ds p ope y
op imiza ion.
Figu e 1.11: C ys allog aphic ela ions be ween L21 aus eni e and non-modula ed L10 ma ensi e. Fo
NiMnSn s oichiome ic alloys, X a e Ni a oms, Y a e Mn a oms and Z a e Sn a oms.
The Heusle - ype MMSMAs a e e y sensi i e o composi ion in e ms o
phase ans o ma ion empe a u e[61][62], Cu ie empe a u e[63], sa u a ion
magne iza ion[64], which, in u n, a e di ec consequence o a c ys al s uc u e
a ia ion[65]. Also, pos -annealing and cooling a es ha e a s ong in luence on
he magne ic p ope ies[66], as phase changes occu due o a omic o de ing.
Ma e ial p ocessing may deg ade he magne ic p ope ies o hese compounds,
bu hese can be e e sed by pe o ming hea ea men s[60].
1.4.1.1. E ec s o doping
(a) Co addi ion
The modi ica ion o he Ni/Mn/Sn a io in Heusle NiMn-based alloys
in luences hei magne ocalo ic p ope ies and ans o ma ion cha ac e is ic
26
In oduc ion
empe a u es. Ne e heless i is di icul o shi he ma ensi ic ans o ma ion
owa ds oom empe a u e wi h jus a ying ha a io, while simul aneously
ha ing a la ge magne ocalo ic e ec a low ields. Adding Co o Ni-Mn-Sn
alloys allows o ob ain sui able ma e ials o magne ic cooling due o he s ong
in luence o Co on magne ic and s uc u al p ope ies. Ni-Co-Mn-Sn sys em
has been widely s udied by se e al g oups. K enke e al. s udied he in luence
o subs i u ing Co o Ni in Ni50-xCoxMn37Sn13 alloys on he magne ocalo ic
e ec [67]. They ound ha in oducing Co led o a dec ease in Ms and ΔS bu
he he mal hys e esis associa ed wi h he ansi ion became na owe wi h Co
con en om 1 o 3 a .%. Simila ly, Cong e al. pe o med a sys ema ic s udy o
he Ni50-xCoxMn39Sn11 alloys and ob ained a phase diag am ela ing he chemical
composi ion o empe a u es o phase ansi ions and magne ic beha iou [68].
pu a
Figu e 1.12 shows he ela ionship be ween ans o ma ion empe a u es
and he Co con en , anging om 0 o 19 a .%. The ma ensi ic ans o ma ion
empe a u e, de ined in his s udy as (Tms+Tm +Tas+Ta )/4, shows a oughly
linea nega i e dependence wi h inc easing Co con en un il 7 a .% o Co and
s ong nega i e exponen ial dec ease o mo e han 7 a .% o Co con en . The
linea slow dec ease o TM is asc ibed o he change o e/a a io. The
subs i u ion o Ni (10 alence elec on) by Co (9 alence elec on) dec eases he
e/a and, as consequence, leads o a dec ease o TM. Fo highe Co con en , he
apid dec ease may be due o a omic o de , p ecipi a ion o o he phases, e c.
In pa icula , he o ma ion o he seconda y 𝛾 phase was obse ed ha has a
di e en composi ion han he ma ix. The aus eni e Cu ie empe a u e
inc eases wi h inc easing Co con en and seems o be co ela ed o he
s eng hening o he e omagne ic exchange in e ac ions wi h Co doping.
Based on he diag am, i can be no ed ha he mos in e es ing ange o
composi ions, om a p ac ical poin o iew, is be ween 5 and 8 a .% o Co
since in his egion MT occu s wi h la ge magne iza ion change ha bene i s
he magne ocalo ic e ec . The addi ion o Co also a ec s he c ys al s uc u e
27
Chap e 1
wi h he o ma ion o modula ion om 4O o 10M and hen o 14M wi h an
inc ease o Co con en .
Figu e 1.12: Phase diag am o Ni-Co-Mn-Sn sys em. The e olu ion o he cha ac e is ic ans o ma ion
empe a u es e sus he Co con en is displayed [68].
(b) Cu addi ion
Cu addi ion o he Ni-Mn-Sn Heusle alloys also enhances he
magne ocalo ic p ope ies and in luences he c ys al s uc u e and phase
ans o ma ion empe a u es. Das e al. in es iga ed he alloys sys em o Ni44-
xZxMn43Sn11 (Z = Co, Cu) and he e ec o Co e sus Cu doping o
magne ocalo ic p ope ies as well as o ans o ma ion empe a u es. Cu
doping led o a dec ease in bo h ma ensi ic and magne ic ans o ma ion
empe a u es. Subs i u ing Cu o Ni inc eased ΔSM signi ican ly, ha ing an
e en s onge e ec han he addi ion o Co[68]. The dec ease o Tms wi h Cu
subs i u ion o Ni is opposi e o wha would be expec ed by he e/a ule. In
his case, ano he ac o such as he uni cell olume should be conside ed. On
he o he hand, he eplacemen o Mn by Cu in Ni43Mn46-xCuxSn11 inc eases

28
In oduc ion
bo h magne ic and ma ensi ic ansi ion empe a u es. In his case, ΔSM
inc eases wi h he addi ion o Cu[69]. The magne ocalo ic p ope ies a e
imp o ed due o a la ge magne iza ion change a ma ensi ic ans o ma ion
om aus eni ic o ma ensi ic phases caused by Cu addi ion. I was
demons a ed ha Cu enhances e omagne ic exchange in e ac ion in aus eni e
esul ed in he men ioned g ea e magne iza ion change a MT[70].
1.4.1.2. E ec o ab ica ion me hods
The ab ica ion me hod has a signi ican e ec on he p ope ies o he
esul ing alloy. Fo alloy syn hesis, he mos popula me hods a e induc ion
cas ing and a c-mel ing. In he labo a o y condi ions, he o me echnique
o e s he possibili y o p epa e alloys in la ge quan i ies (se e al ens o g ams),
whe eas he la e one should no exceed a ew g ams. The eason is ha
induc ion cas ing uses la ge c ucible in which a la ge quan i y o alloy i s and
ha can be comple ely and simul aneously mel ed, gi ing ise o a a he
homogeneous liquid alloy ha will main ain i s homogenei y when cas ed a a
high quenching a e. In his me hod, pos annealing is equi ed o imp o ing a
homogenei y. Ano he d awback o his echnique is ha he alloy is suscep ible
o eac ion wi h he alumina c ucible i o e hea ed in a liquid s a e o keeping
liquid oo long. On he o he hand, a c mel ing u nace gene ally p o ides
homogeneous alloy as long as i s mass is less han 10 g ams since o he wise he
a c canno mel he en i e cons i uen s simul aneously, p e en ing i om
becoming a ully homogeneous ingo . Flipping and e-mel ing he ingo a ew
imes assu e he alloy homogenei y.
Mel -spinning is a echnique ha p oduces me allic ibbons o lakes
which could be a single-phase wi hou chemical seg ega ion. The high cooling
a e in no mally p e en s he o ma ion o unexpec ed phases[71]. This
echnique allows o sho en o e en a oid a long annealing, leading o lowe
ab ica ion cos and he ab ica ion ime. In addi ion, mel -spinning p ocess
29
Chap e 1
in luences a omic o de , which a ec s he magne ic p ope ies and ma ensi ic
ansi ion empe a u es. Gene ally, MMSMAs ibbons ha e a lowe MT han
he bulk alloys, and his is a ibu ed o g ain e inemen and in e nal s esses
o med du ing ab ica ion [72].
1.4.1.3. Hea ea men s
The unc ional p ope ies o a ma e ial can be imp o ed by pe o ming
speci ic hea ea men s. On he o he hand, ma e ial p ocessing like mel -
spinning, g inding p ocess o powde ob aining, o any pos p ocessing may
deg ade i s magne ic p ope ies. This deg ada ion can be pa ially o comple ely
e e ed by pe o ming speci ic hea ea men s o he ma e ial. Ano he
p ope y ha can be enhanced is he he mal hys e esis educ ion since hea
ea men s ha e in luence on he mic os uc u e, phase ansi ions, and
magne ic p ope ies o hese ma e ials. Hea ea men s a ec in a ious
manne s o he ma e ial:
1) Phase T ansi ion S abiliza ion: Heusle magne ocalo ic ma e ials
ypically unde go phase ansi ions when exposed o a ying magne ic
ields. These phase ansi ions a e essen ial o he magne ocalo ic e ec ,
bu hey can in oduce hys e esis. Hea ea men s can s abilize hese
phase ansi ions, making hem mo e ep oducible and educing
hys e esis.
2) Mic os uc u al changes: Hea ea men s can induce changes in he
mic os uc u e o he ma e ial. Fo example, hey can p omo e he
g ow h o speci ic c ys al g ains o he elimina ion o de ec s. These
mic os uc u al changes can esul in a mo e uni o m and well-de ined
esponse o he ma e ial o changes in empe a u e and magne ic ield.
30
In oduc ion
3) Homogeniza ion: Hea ea men s can help in he homogeniza ion o he
ma e ial composi ion. Inhomogenei ies o composi ional a ia ions
wi hin he ma e ial can lead o i egula phase ansi ions and hys e esis.
Hea ea men s can e en ou hese a ia ions and imp o e he ma e ial's
consis ency.
4) Magne ic p ope y op imiza ion: The magne ic p ope ies o Heusle
magne ocalo ic ma e ials a e closely linked o hei phase ansi ions.
Hea ea men s can help op imize hese magne ic p ope ies, such as he
Cu ie empe a u e and he sa u a ion magne iza ion.
5) S ess Relie : Du ing he ab ica ion p ocess, magne ocalo ic ma e ials
may expe ience s ess o s ain, which can a ec hei magne ic and
he mal beha iou . Hea ea men s can elie e hese in e nal s esses
and es o e he ma e ial o a mo e s able and s ess- ee s a e.
6) De ec Annealing: Any de ec s o disloca ions in he c ys al la ice o he
ma e ial can dis up i s magne ic and he mal beha iou . Hea ea men s
can acili a e de ec annealing, educing hese dis up ions and p omo ing
mo e p edic able phase ansi ions.
O e all, hea ea men s a e a aluable ool in op imizing he p ope ies o
Heusle magne ocalo ic ma e ials. They help achie e mo e con olled and
p edic able phase ansi ions, leading o a educ ion in he mal hys e esis and,
ul ima ely, enhancing he e iciency and eliabili y o hese ma e ials o cooling
and e ige a ion applica ions.
31
Chap e 1
1.5. APPLIED ASPECTS OF MAGNETOCALORIC MATERIALS
pu a
The main po en ial applica ion o magne ocalo ic ma e ials is o magne ic
e ige a ion. Bo h i s -o de magne ocalo ic (FOMT) and second-o de
magne ocalo ic (SOMT) ma e ials a e gene ally used o magne ic e ige a ion
and hea pumping[73]. I is clea ha a magne ocalo ic ma e ial exhibi ing a
la ge magne ocalo ic e ec is desi able o e ige a ion. One o he pa ame e s
o measu ing he u ili y o a magne ocalo ic ma e ial is i s magne ic ield –
induced iso he mal en opy change, a quan i y ha is usually epo ed in e e y
s udy de o ed o a magne ocalo ic ma e ial. Howe e , his is no only pa ame e
needed o be aken in o accoun since i does no p o ide in o ma ion abou
he usabili y o he ma e ial o a e ige a ion de ice, because hea is no
ans e ed iso he mally. The main pa ame e ha mus be aken in o accoun
is he magne ic ield –induced adiaba ic empe a u e change since i p o ides a
basis o es ablishing he capaci y o magne ocalo ic ma e ial o c ea e he
empe a u e g adien . The la ges possible adiaba ic empe a u e change is
equi ed o o e come he i e e sible hea losses because o he i e e sibili y
o he hea ans e be ween he ma e ial and he hea ans e ing luid.
pu a
The e o e, i is desi able o ha e magne ocalo ic ma e ials wi h he la ges
adiaba ic empe a u e change pe magne ic ield uni , aking in o conside a ion
en i onmen al, geopoli ical and esou ces issues associa ed wi h p ac ical
applica ions. Gd-based ma e ials a e conside ed c i ical in his ega d [74], while
he chemical elemen s in NiMn-based Heusle compounds a e in a common
use, which is one o he easons o choosing hese ma e ials o his hesis.
1.5.1. Ac i e Magne ic Regene a o s
The empe a u e span equi ed o magne ocalo ic e ige a ion is g ea e
han he one a magne ocalo ic ma e ial can p o ide by i sel , al hough i is
enough o low empe a u e adiaba ic demagne iza ion e ige a ion due o he
38
In oduc ion
1.8. OBJECTIVES
A global objec i e o he p esen wo k is o de elop p ac ically new
unc ional ma e ial such as powde ed high e icien Heusle - ype MMSMA
exhibi ing MT and MCE cha ac e is ics simila o a bulk homolog and being
sui able o addi i e manu ac u ing o a hea exchange p o o ype. We will
pu sue he nex less scoped objec i es:
1. Explo ing ans o ma ion beha iou o he ep esen a i es o he main
amilies o Heusle - ype NiMn-based MMSMAs in o de o selec a
p ospec i e alloy which will se e, a he end, as p o o ype MCE powde
componen o p in ing ink.
2. P epa a ion and all- ound s udy o MMSMA ibbons as he p ecu so s o
ab ica ion o he MCE unc ional powde
3. All- ound in es iga ions o MMSMAs powde s p epa ed om ibbons
4. Elucida ing condi ions needed o c ea e me allic p in able inks
5. 2D and 3D p in ing o MCE p o o ype de ices using a de eloped
MMSMA/polyme inks and un eiling hei cha ac e is ics.

39
Chap e 1
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Chap e 2
Chap e 2
Expe imen al Me hods
54
Expe imen al me hods
2.6. INK PREPARATION
Once a p ope powde is ob ained i is hen used o he ink manu ac u e.
The goal is o make an en i onmen ally- iendly app oach and o ha he
polyme s selec ed o ink ab ica ion we e hose ha sa is y en i onmen ally-
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p ocessabili y and good ilm o ming capaci y. Speci ically, he inks consis o
h ee elemen s:
 Me allic powde : Comme cial Fe, Al and Si powde and ab ica ed
powde o NiMn-based Heusle alloy
 Ma ix: a polyme ha ac s as a binde ⇒ Hyd oxyp opyl Cellulose
(HPC), Collagen and Silk.
 Dissol en : Deionized H2O
2.6.1. Collagen-based ink
The sou ce o collagen o ink p epa a ion was a salmon skin which
p o ides a good quali y collagen wi h good mechanical p ope ies. The i s s ep
is o sepa a e he collagen om he skin. Fo ha , he scales and muscles we e
emo ed, and skin piece was u he washed wi h wa e and cu in o pieces o
abou 2 x 2 cm. Then, o a emo al om he skin, he pieces a e imme sed
in 10% e hanol o 48h, unde s i ing ( he solu ion is eplaced wice a day). In
o de o emo e non-collagenous p o eins he skins a e hen ea ed wi h 0.1M
NaOH (1:10 w/ ), du ing 3 x 2 h. A e ho ough washing wi h wa e , salmon
skins a e dissol ed in 0.5M ace ic acid (1:10 w/ ) du ing 72h, unde s i ing.
Then he esul ing mix u e is cen i uged and he supe na an , con aining he
acid soluble collagen is u he acuum il e ed o emo e non-soluble
impu i ies. Now, salmon skin collagen is eco e ed by sal ing ou and a e
cen i uga ion is suspended in 0.5 M o ace ic acid, dialyzed agains 0.1 M ace ic

55
Chap e 2
acid. Then i is eeze-d ied un il u he use. All he ex ac ion p ocedu e is
conduc ed a 4 ºC.
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2.6.2. Silk-based ink
Fo silk-based ink p epa a ion we s a om Bombyx mo i silkwo m
cocoons by a s anda d me hod, named soap degumming[2]. Each cocoon is cu
in hal , and he in e nal su ace is cleaned mechanically. Then, se e al small
pieces o 1 cm2 a e cu . The silk cocoon is basically composed by wo elemen s:
(i) Silk ib oin, which is he polyme we a e in e es ed in; and (ii) se icin, ha
ac s as a glue joining he ib es. Fo sepa a ing he se icin om he ib oin, he
pieces o cocoons a e in oduced in an alkaline solu ion o 0.05 w %. 𝑁𝑎2𝐶𝑂3
(see Figu e 2.3) and is hea ed up o 95ºC (abo e 100ºC he chains s a s o b eak
bu we wan o a oid his) and le 10 minu es, epea ing his Degumming p ocess
one mo e ime. In his p ocess he Hyd ogen b idges o he polyme a e b oken.
A e his p ocess whi e nea ib es a e ob ained and hey a e le d ying
o e nigh .
pu a
The second pa o his ink p epa a ion p ocess consis s on dissol ing he
silk ib oine (SF) o ob ain a gel. To accomplish his ask he d ied ib es a e
in oduced in a solu ion ha is p epa ed wi h [4g CaCl2 x 2H2O + 4mL H2O +
1.5 ml E OH] pe 0.5g o ib oine. The e hanol helps b eaking Hyd ogen
b idges. The solu ion is hea ed up o 80ºC and magne ically mixed a 400 pm.
This p oduces a solu ion o 8% o ib oin in wa e . Then he mix is in oduced
in a dialysis casse e (cu -o : 30kDa) and is le o 6 hou s. A e he sal
emo al he inal p oduc is a solu ion o wa e and ib oin wi h 2% o
concen a ion. This solu ion is me as able and may ha e wo phases: Dissol ed
and P ecipi a ed. The solu ion is cen i uged 5min a 7500 pm o emo e any
solid esidue ha could be in i (Figu e 2.3).
The d ied silk is semi-c ys alline and du ing u he p ocessing he Hyd ogen
b idges a e b oken, gi ing ise o an amo phous ma e ial, which will be d ied.
56
Expe imen al me hods
Figu e 2.3: Schema ic o he ou e o silk p epa a ion.
The me allic ink is p epa ed by mixing me allic powde wi h SF and o mic
acid ha imp o es he iscosi y in o de o well-dis ibu e he me allic pa icles
wi hin he ink.
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2.6.3. Cellulose-based ink
The low cha o cellulose-based ink p epa a ion is schema ically shown
in Figu e 2.4. The p epa a ion o he ink consis s on dissol ing he HPC in
dis illed wa e by manual s i ing and lea ing o 24 hou s a oom empe a u e
un il ai bubbles a e emo ed and he HPC is comple ely dissol ed. Then he
me allic powde is added and he mix is manually s i ed du ing 5 minu es un il
homogeniza ion.
Figu e 2.4: The low cha o he expe imen al p ocedu e o ink p epa a ion and bubble emo al.
57
Chap e 2
The p ocess o manual s i ing in oduces ai bubbles wi hin he iscous
ink lea ing i o non-op imal p in ing. In oducing he ink in a acuum
chambe emo es ai bubbles a e 2-3 cycles o acuuming. The wa e
e apo a ion in his p ocess is minimal (less han 5%) so he wa e educ ion can
be neglec ed. A e acuuming he ink is in oduced in o a 10mL sy inge o
being s o ed and/o o s a p in ing. In some cases he sy inge is acuumed
du ing 2 minu es o emo ing comple ely emaining bubbles ha may be
in oduced in he p ocess o illing i .
2.7. 2D PRINTING
2.7.1. Doc o Blade
The i s s ep o ink es ing was done by Doc o Blade, a echnique ha
consis s on deposi ing a d op o ink in a subs a e and hen passing a sha p
blade a a ce ain heigh (in ou case 0.5mm). This echnique p o ides a
homogeneous ilm ha is le d ying a oom empe a u e o e nigh . Figu e 2.5
shows he scheme o he wo king p inciple[3].
Figu e 2.5: Gene ic scheme o ilm p epa a ion by doc o blade echnique. In ou case he d ying empe a u e was oom-
empe a u e.
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2.7.2. Sc een-p in ing
A e doc o blade es s, he i s p in ing es s o he p epa ed inks we e
done by 2D p in ing using he sc een-p in ing me hod (Figu e 2.6). The de ice
used o his es s is he Wenzhou Zhengchang Machine y ZH3040H. The ink
is deposi ed in he o m o chips on he sc een mesh and, using a manual
58
Expe imen al me hods
sc appe , is di ec ed o he p in ing pa e n unde which a PET subs a e is
placed, whe e he ink is deposi ed. Since me allic inks a e magne ic, placing a
pe manen magne unde he subs a e can o ien a e he pa icles wi h hei
magne ic easy axis along he magne ic ield. To inc ease he amoun o magne ic
ma e ial, 10 laye s a e p in ed one on op o he o he .
Figu e 2.5: Sc een-p in ing se up (le ) and de ail o he ink deposi ion in he subs a e in he p in ing p ocess, whe e i
is o ien ed by he pe manen magne placed below he subs a e ( igh ).
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2.8. 3D PRINTING
3D s uc u es a e p in ed using he cold-ex usion echnique (also known
as sol en -cas p in ing) using Tissue Sc ibble p in e (3dcul u es). The scheme
o cold-ex usion echnique is shown in Figu e 2.7. The me allic ink, which now
p esen s a he iscous pas e, is loaded in o a 10 mL sy inge a ached wi h a
ape ed nozzle wi h exi inne diame e o 410μm. The s uc u es a e p in ed in
a PET (Polye hylene Te eph hala e) oil subs a e ha is s uck in o a le elled
glass su ace. In o de o ensu e p ope PET subs a e adhesion o he glass
su ace small d ops o wa e a e deposi ed a he co ne s o PET subs a e so a
hin laye o wa e en e s by capilla i y be ween he subs a e and he glass
su ace. The p in ing speed in his wo k a ies om 200 mm/min o 300
mm/min, depending on he ink iscosi y. The sy inge ex usion a e is o 1.15
ml/hou . These alues o p in ing speed and ex usion a e we e chosen o ge
a balance be ween he ex usion a e wi h nozzle ansla ion speed (p in ing
speed). To accele a e he d ying a e, a cooling an (DC 5.5V, 0.55W, 250mm
om he p in e nozzle) is used so he e is a con inuous ai low. This ensu es
59
Chap e 2
ha he p in ed laye is going o be deposi ed in o a d ied p e ious laye since
o he wise he laye - o-laye adhesion is no op imal.
Figu e 2.6: Schema ic model o ex usion 3D p in ing echnique used.
2.9. CHARACTERIZATION METHODS
2.9.1. Vib a ing Sample Magne ome e (VSM)
The magne ic and ans o ma ion cha ac e iza ion we e pe o med by
using he ib a ing sample magne ome e (VSM) om Mic oSense Inc. ( he
magne ic ield and empe a u e anges a e 0-2 T and 100-500 K, espec i ely).
Wi h his cha ac e iza ion echnique he empe a u e and magne ic ield
induced phase ans o ma ions can be e ealed by pe o ming magne iza ion
e sus empe a u e and magne iza ion e sus magne ic ield measu emen s.
The wo king scheme o he VSM is shown in Figu e 2.8. The sample is placed
wi hin a uni o m magne ic ield (up o 2 T) and he sample holde ib a es in
he Z-axis a a gi en equency and he coils placed in he ends o he
elec omagne s measu e he signal change by a magne ic induc ion p inciple.
The empe a u e is con olled by a con inuous ai lux ha passes h ough a
esis o ha hea s i by applying a ce ain ol age. Fo he measu emen s below
oom empe a u e he coppe ube whe e he ai goes o he u nace is
subme ged in o a liquid ni ogen so he ai is cooled down.

60
Expe imen al me hods
Figu e 2.7: Scheme o he wo king p inciple o he VSM.
2.9.2. Supe conduc ing Quan um In e e ence De ice (SQUID)
Fo high magne ic ield measu emen s (up o 7 T) a SQUID-VSM
magne ome e om Quan um Design Inc. was used. This de ice allows o
measu e smalle samples han he VSM since i s sensi i i y is a highe han he
VSM one. The measu emen empe a u e ange is om 5K o 400K.
2.9.3. Di e en ial Scanning Calo ime y (DSC)
Di e en ial scanning calo ime y is a he moanaly ical echnique whe e
he amoun o hea equi ed o inc ease he empe a u e o a sample and a
e e ence is measu ed as a unc ion o empe a u e. Du ing he measu emen a
e e ence sample wi h a well-de ined hea capaci y o e he ange o he
empe a u es o be scanned is main ained a oughly he same empe a u e as
he measu ing sample. Wi h his echnique empe a u e induced phase
ans o ma ions can be de ec ed and cha ac e ized. In he p esen wo k a
Me le -Toledo DSC822e calo ime e ( amp 20 K/min), unde N2 a mosphe e
was used.
61
Chap e 2
2.9.4. Scanning Elec on Mic oscopy (SEM)
Fo mic os uc u e analysis a scanning elec on mic oscope (SEM) was
used (Hi achi TM 3000). I was equipped wi h an ene gy-dispe si e X- ay
spec oscopy (EDS, o also known as EDX) o composi ion measu emen s.
The sample o be measu ed is placed in he sample holde using ca bon ape,
o ensu e elec ical conduc i i y be ween hem. The g ains size, ibbon
hickness, mo phology e c. can be s udied wi h his echnique. Composi ion
mapping was done wi h he EDX measu emen s.
2.9.5. Magne ic ield-induced adiaba ic empe a u e change
A cus oma y de eloped echnique o di ec measu emen s o adiaba ic
empe a u e change was used o magne ocalo ic cha ac e iza ion o he
samples. The schema ic o he de ice is shown in Figu e 2.9 [4]. MCE
measu emen s mus be pe o med unde adiaba ic condi ions which mean ha
he sample mus be he mally insula ed by: (i) co e ing he sample wi h Te lon
ape o ensu e he mal insula ion by conduc ion, (ii) he chambe whe e he
sample holde is going o be moun ed is kep a cons an acuum o ensu e
he mal insula ion by con ec ion and (iii) he shield ha has he capsule whe e
he sample is placed is made ou o Coppe a oiding he mal losses by in a ed
adia ion.
Fo making he measu emen he sample is di ided in wo pieces and is
moun ed in he sample holde so he he mocouple is embedded be ween he
wo pieces o he sample. Fo p ope hea ans e o he he mocouple a sil e
pas e is used. Then he sample is pu in con ac wi h he hea e which is
in eg a ed in he alumina-based sample holde and insula ed wi h Te lon ape.
The sample holde is hen moun ed in he sys em be ween wo poles o a
elec omagne ha p o ides a cons an magne ic ield.
62
Expe imen al me hods
Figu e 2.8: Ske ch o he expe imen al se up (a). The sample holde wi h hea e assembly (b) [4].
pu a
The empe a u e is con olled by a hea e a ached o he sample holde
ha hea s he sample by he mal con ac . Fo cooling below he oom
empe a u e a lux o ai , cooled down by liquid ni ogen, is passed h ough an
ex e nal ca i y close o he ca i y whe e he sample holde is placed. The
p ocedu e o he measu emen is o hea up he sample un il ull aus eni ic
phase is eached and hen cooling down o he selec ed empe a u e o
measu emen . Then he sample is emo ed om he magne ic ield by a
hyd aulic sys em and he alue o he empe a u e change is measu ed by he
he mocouple.
3.9.5. Mechanical cha ac e iza ion
Mechanical cha ac e iza ion was pe o med o he p in ed s uc u es
unde comp ession a 1 mm/min speed using Shimadzu AGS-J 500M de ice.
3.9.6. X-Ray Di ac ion (XRD)
X- ay di ac ion pa e ns (XRDP) a e ob ained using a B uke D8
Ad ance di ac ome e (30 kV and 20 mA, λCu = 1.5418 Å) and he FullP o
sui e o he e inemen .
63
Chap e 2
2.9.7. Magne ic ield induced en opy change calcula ion
As explained in he in oduc ion, he magne ic en opy change can be
calcula ed by in eg a ing he magne iza ion e sus empe a u e cu es by he
Maxwell he modynamic ela ionship
∆𝑆𝑚(𝑇,𝐻)= 𝑆𝑚(𝑇,𝐻)−𝑆𝑚(𝑇,0)=∫(𝜕𝑀(𝑇,𝐻′)
𝜕𝑇 )𝑑𝐻′
𝐻
0
The calcula ions we e done using Scilab ® so wa e and he da a ob ained
om he SQUID isomagne ic magne iza ion e sus empe a u e
measu emen s.
70
Ribbons o Heusle - ype Magne ic Shape Memo y Alloys
he le panel which can indica e on a much mo e deg ee o b i le ailu e o he
HT sample compa ed o he as-spun coun e pa .
3.2.1.2. T ans o ma ion cha ac e is ics
The measu emen o he empe a u e dependences o low- ield
magne iza ion, M(T), is a common ool o in es iga e he ans o ma ion
beha iou , magne ic s a e and de e mine he MT and Cu ie empe a u es in
MMSMAs [4–6]. As discussed in he sec ion 3.1 and Re . 3, h ee hea
ea men s we e pe o med on as-spun ibbons in o de o ind he op imal
one[7]:
(1) 723 K 30’ + q
(2) 1173 K 60’ + q
(3) 1173 K 60’ + q & 723K 30’ + q
The q s ands o “quenching” which means a e y apid cooling he
sample down o 273 K by imme sing i in iced wa e immedia ely a e he hea
ea men . This is done in o de o e ain he high empe a u e phase s a e. I
was ound ha each hea ea men has a di e en e ec on he alloy. The i s
one (1) imp o es he chemical o de in he c ys al s uc u e, whe eas he second
one (2) imp o es he s uc u al o de and educes he su ace mic o-s ains
p oduced du ing he mel -spinning echnique. The hi d hea ea men (3) is a
combina ion o he wo p e ious ones esul ing in being he op imal one.
Figu e 3.2 depic s he low- ield he momagne iza ion cu es o bo h he
as-spun and hea - ea ed ibbons samples, which we e used o selec he op imal
hea ea men egime. When cooling om he high empe a u e pa amagne ic
aus eni e, he magne iza ion exhibi s a apid inc ease due o he e omagne ic
o de ing o he aus eni ic phase a he Cu ie empe a u e. A he ma ensi ic
ans o ma ion, which also ep esen s a magne ic ansi ion om he
e omagne ic aus eni e o he an i e omagne ic ma ensi e [8], he
magne iza ion apidly d ops o almos ze o. This s ong change in he magne ic

71
Chap e 3
s a e cha ac e izes a magne os uc u al i s -o de ans o ma ion ha can be
easily induced by a magne ic ield, esul ing in se e al ema kable p ope ies,
pa icula ly a signi ican in e se magne ocalo ic e ec [6,9–11].
The he momagne iza ion cu es o ibbons in he as-spun and hea -
ea ed condi ions a 723 K show educed MT empe a u es and enhanced
empe a u e hys e esis (Figu e 3.2). These beha iou s e lec he
inhomogeneous s a e o he samples, including composi ion g adien s, in e nal
s esses, de ec s e c., caused by he ab ica ion echniques, such as apid
solidi ica ion du ing mel -spinning.
Expe imen s demons a e ha he composi ional and s uc u al
impe ec ions could no be elimina ed by he hea ea men a 723 K o 30
min. Figu e 3.2 shows conside ably be e MT pa ame e s o he samples
ea ed a 1173 K and quenched, wi hou addi ional aging o aged a 723 K.
Samples in hese s a es exhibi nea ly ec angula shape M(T) loops wi h
educed hys e esis, app oxima ely 30 K. In his case, he hea ea men s
p oduce a much mo e homogeneous s a e in he samples, which a e also elaxed
om in e nal s esses and exhibi ewe s uc u al de ec s, as e idenced by he
XRD esul s (see chap e 4, sec ion 4.2.1.2.).
Figu e 3.2: The momagne iza ion cu es o Ni40Mn42.5Co8Sn9.5 ibbons wi h di e en hea ea men s.
72
Ribbons o Heusle - ype Magne ic Shape Memo y Alloys
These ibbons a e sui able o powde p oduc ion since he
ans o ma ion a e hea ea men s occu s nea oom empe a u e, making
his alloy sui able o (nea ) oom- empe a u e cooling. The sui abili y o his
alloy in powde o m o p in ing is discussed in chap e 4.
3.2.2. Mn48Ni35.5Sn8Co6.5Fe2
3.2.2.1. Composi ion and mic os uc u e
Wi h he in en ion o inc ease MT empe a u e and inc ease a jump o
M(T) a MT we ha e ab ica ed Ni(Co)MnSn ibbon wi h educed Sn and Co
and inc eased Ni con en s and added Fe a oms, whe eby he nominal
composi ion o his MMSMA became Mn48Ni35.5Sn8Co6.5Fe2 . The ac ual
composi ion o his ibbon was e alua ed by EDS. Table 3.2 summa ize he
ibbon composi ion, which is an a e age o he measu emen s on 10 ibbon
pieces.
Table 3.2: Ac ual composi ions o he as-spun and hea ea ed ibbons de e mined by EDS analysis.
Sample
Mn (a %)
Ni (a %)
Sn (a %)
Co (a %)
Fe (a %)
As-spun ibbons
48.2
35.2
7.5
6.5
2.8
HT ibbons
42.3
34.0
15.0
6.3
2.3
The Table 3.2 shows ha con en o all elemen s in as-spun ibbon a ies
wi hin ± 1 a % om he nominal one, which co esponds o he ins umen al
unce ain y o he composi ion de e mina ion by ou EDS analysis, whe eas he
con en o Mn and Sn in HT ibbon is modi ied. I is known ha bo h a Mn
educ ion and inc easing Sn a ou a shi ing he MT empe a u es owa ds low
empe a u es.
The c oss-sec ional iew o ibbon is documen ed by SEM imaging shown
in Figu e 3.3(le ). I e eals a ibbon hickness o abou 20μm and does no
show a well-p onounced columna s uc u e. Fig. 3.3( igh ) shows a he
globula han well-c ys alized g ain mic os uc u e wi h he uni o m size o he
indi idual g ains equal o abou 1 m in diame e .
73
Chap e 3
Figu e 3.3: SEM c oss-sec ional iew image o he ibbon (le ) and g ain s uc u e obse ed in he shiny su ace o he
ibbon, which was in con ac wi h cope wheel ( igh ).
3.2.2.2. T ans o ma ion cha ac e is ics
The i s measu emen ha gi es an insigh on he ans o ma ion
beha iou , he Cu ie empe a u e, and MT empe a u e is he low- ield
magne iza ion e sus empe a u e cu e[12][13]. Figu e 3.4 shows
magne iza ion e sus empe a u e dependences o he as-spun and hea -
ea ed ibbons a low magne ic ield. P e ious wo ks ha e shown ha
pe o ming special hea ea men s may imp o e phase ans o ma ion and
educe hys e esis in Heusle MMSMAs[14]. Howe e , he hea ea men s ha
usually wo k well o he alloys in Re .[16] go de imen al wi h he alloy s udied
he e, as Figu e 3.4 shows. In his case, he ma ensi ic ans o ma ion is less
ab up , and he ans o ma ion on is no smoo h indica ing ha hea
ea men esul s in some inhomogenei ies in he sample. The la e ones a e
esponsible o a dec ease o he magne ic suscep ibili y o alloy. All hese
e ec s a e in ag eemen wi h he composi ion changes ou lined in Table 3.2.
Mn is suscep ible o e apo a ion and since his alloy has a high manganese
con en , he hea ea men s can ha e a g ea e impac on he alloy
s oichiome y, pa icula ly, causing a dec ease o he MT empe a u es, as his
end was al eady men ioned.
74
Ribbons o Heusle - ype Magne ic Shape Memo y Alloys
On he o he hand, he oom empe a u e ans o ma ion cha ac e is ics
and magne ic p ope ies in he as-spun ibbon a e sa is ac o y. The e o e, he
ad an age o his alloy lies in he ac ha no u he ea men is necessa y,
educing p oduc ion cos s and ene gy consump ion. Thus, his alloy is going o
be s udied in i s as-spun ibbon o m om his poin o iew. The alues o
ma ensi ic and aus eni ic ans o ma ion empe a u es, TM and TA espec i ely,
a e lis ed in Table 3.3.
Figu e 3.4: The momagne iza ion cu es o as-spun and hea ea ed ibbons.
Table 3.3: Cu ie empe a u e and aus eni ic and ma ensi ic ans o ma ion empe a u es ex ac ed om he
he momagne iza ion cu es o as-spun and hea ea ed ibbons.
Sample
TCA (K)
TM (K)
TA (K)
As-spun ibbons
423
298
331
HT ibbons
408
225
265
3.2.2.3. “Magne ic ield – empe a u e” phase diag ams o ma ensi ic
ans o ma ion
The he momagne iza ion cu es, M(T,H), o he as-spun ibbons
eco ded unde di e en magne ic ields a e shown in Figu e 3.5. In his igu e,
he magne ic ield e ec on MT is seen as a displacemen o he MT hys e e ic
loop owa ds lowe empe a u es, which is a ypical beha iou o MMSMAs
75
Chap e 3
and a ibu ed o he magne ic ield induced s abiliza ion o he aus eni ic
phase[13]. The alues o ma ensi ic empe a u e (TM) and aus eni ic
empe a u e (TA) a e ex ac ed om M(T,H) cu es using he de i a i e
me hod. They a e plo ed as a unc ion o magne ic ield ep esen ing quasi-
equilib ium phase diag am o MT shown in he inse o Figu e 3.5. The da a in
Figu e 3.5 can be app oxima ed by almos pa allel o each o he s aigh lines
ha ing nega i e slope o (-2.4±0.2) K/T o TA and (-1.8±0.3) K/T o TM,
de e mined by linea i ing.
Figu e 3.5: The momagne iza ion cu es a di e en applied magne ic ields. Inse shows empe a u e-magne ic ield
phase diag am o MT.
magne ocalo ic
3.2.2.4. Magne ic ield induced en opy change
Con en ional and in e se magne ocalo ic e ec s a e cha ac e ized by he
iso he mal en opy change, ∆𝑆𝑚(𝑇,𝐻), and/o adiaba ic empe a u e change,
∆𝑇𝑎𝑑(𝑇,𝐻), when a magne ic ield is applied o emo ed in iso he mal
condi ions. By means o Maxwell he modynamic ela ionships he magne ic
ield induced en opy change can be es ima ed [15]. I is a common p ac ice

76
Ribbons o Heusle - ype Magne ic Shape Memo y Alloys
ha Maxwell ela ionship is applied o he i s -o de phase ansi ions. F om
he he momagne iza ion cu es a di e en magne ic ields (Figu e 3.5) he
calcula ion o ∆𝑆𝑚(𝑇,𝐻) can be done by nume ical app oxima ion o he
Maxwell ela ionships, as explained in chap e 2:
∆𝑆𝑚(𝑇,𝐻)=𝑆𝑚(𝑇,𝐻)−𝑆𝑚(𝑇,0)=𝜇0∫(𝜕𝑀(𝑇,𝐻′)
𝜕𝑇 )𝑑𝐻′
𝐻
0
Figu e 3.6 shows he ∆𝑆𝑚(𝑇,H) plo s calcula ed by using cooling and
hea ing da a om Figu e 3.5 o as-spun ibbon. The cu es show high
maximums a bo h he o wa d and e e se MT. Figu e 3.7(le ) in he nex
subsec ion shows ield dependence o he ∆𝑆𝑚(𝑇,H) maximums.
Figu e 3.6: Magne ic en opy change a MT unde di e en magne ic ields de i ed om M(T) cu es o as-spun
ibbon.
magne ocalo ic
3.2.2.5. Re ige an capaci y
The e ige an capaci y is he amoun o hea ans e ed be ween ho and cold
ese oi s in a single e ige a ion cycle. I can be calcula ed by in eg a ing he
cu e o ∆𝑆𝑚(𝑇,𝐻) a FWHM:
77
Chap e 3
𝑅𝐶≈ ∫ |∆𝑆𝑀(𝑇,𝐻)|𝑑𝑇
𝑇ℎ𝑜𝑡
𝑇𝑐𝑜𝑙𝑑
In eg a ing he cu es om Figu e 3.6 yields he e ige a ion capaci y
e sus magne ic ield dependences o cooling and hea ing cycles depic ed in
Figu e 3.7( igh ). This in eg a ion p ocedu e is e e ed o as a Gschneidne
e ige an capaci y (RC) calcula ion[16]. I is wo h no ing ha ield
dependencies o he maximum o ∆𝑆𝑚(𝑇,𝐻) and RC a e e y simila .
Figu e 3.7: Maximum magne ic en opy (le ) and e ige an capaci y ( igh ) as a unc ion o he magne ic ield.
magne ocalo ic
3.1.2.6. Adiaba ic magne ocalo ic e ec
The adiaba ic empe a u e change, ΔTad, was measu ed by apid inse ing
and emo ing he samples om a cons an magne ic ield o 2 T p oduced by
he elec omagne . These measu emen s ha e been pe o med a cons an
empe a u es du ing s ep-wise hea ing/cooling amps anging be ween 260 K
and 390 K. The esul s a e p esen ed in Figu e 3.8, which shows ha he peak
posi ion is obse ed close o 330 K o he as-spun ibbon, eaching a maximum
alue o ΔTad = │1.9│ K. The ibbon exhibi s a de ined peak o he in e se
magne ocalo ic e ec (nega i e ΔTad(T) alues esul ing om he applica ion
o he magne ic ield) in he icini y o he e e se MT. This ans o ma ion
co esponds o he phase change om a weakly magne ic ma ensi ic phase o
a e omagne ic aus eni e.
78
Ribbons o Heusle - ype Magne ic Shape Memo y Alloys
F om Figu e 3.8 i can be in e ed ha con a y o he occu ence o he
conside able peak o adiaba ic empe a u e change a he e e se MT, no peak
is obse ed a he o wa d MT du ing cooling amp, only one can see a posi i e
ΔTad signal exhibi ing a s ep-like anomaly a he o wa d MT. The hea ing peak
is highly p ominen because he s uc u al ans o ma ion is induced by applied
ield, whe e a ela i ely la ge olume ac ion o ans o med ma e ial is
in ol ed. On he o he hand, in he cooling p ocess, i would be necessa y o
induce he e e se ans o ma ion unde applied magne ic ield om some
po ion o ma ensi e o e coming he MT hys e esis. The e o e no peak was
obse ed unde applied magne ic ield when he sample was s ep-wise cooled
ac oss he o wa d MT. No e, ha in o de o obse e a peak o ΔTad a he
o wa d MT, one need o do measu emen s unde ield emo al. Tha is du ing
cooling he sys em has o be magne ically o de ed in pa ial aus eni ic s a e (wi h
applied magne ic ield) and in he momen o pe o ming he measu emen he
sys ems should go o he diso de ed s a e o ma ensi ic phase (wi h no applied
ield), inducing he ans o ma ion om ma ensi e o aus eni e.
Figu e 3.8: Cooling-hea ing dependences o adiaba ic empe a u e change measu ed unde 2T o as-spun ibbon.
79
Chap e 3
3.2.3. Ni43Mn39Co7Sn11
3.2.3.1. Composi ion analysis
The hi d alloy s udied was he compound wi h a nominal composi ion o
Ni43Mn39Co7Sn11. Wi h his alloy composi ion we conduc ed a s udy o he
in luence o he same- egime mel -spinning p ocessing on ep oducibili y o he
composi ion con en o esul ing ibbons. Expe imen ally, we ha e seen ha i
is almos impossible o ob ain wo o mo e iden ical ibbon composi ions due
o ac o s such as he in oduc ion o weigh e o s du ing he p epa a ion o
p ecu so s and he du a ion o alloy mel ing, which leads o he subsequen
e apo a ion o some o i s cons i uen s du ing he mel -spinning p ocess. The
esul s p esen ed in Table 3.4 indica e ha some a ia ions in he ibbons
composi ions occu .
Table 3.4: Ac ual composi ions o each p epa ed ibbon measu ed by EDS.
Sample
Ni (a %)
Mn (a %)
Co (a %)
Sn (a %)
V0
43.1
39.5
7.2
10.4
V1
43.3
39.8
6.6
10.3
V2
44.7
37.8
7.3
10.2
V3
43.3
39.2
7.4
10.1
V6
43.6
38.6
7.5
10.4
3.2.3.2. T ans o ma ion cha ac e is ics
As a as hese ypes o alloys a e highly sensi i e o such changes, a
no able al e a ion in he magne ic esponse is obse ed, as e iden om he
he momagne iza ion cu es shown in Figu e 3.9. Taking in o accoun he
esul s o he ans o ma ion beha iou shown in Figu e 3.9, we selec ed se e al
ibbons om Table 3.4 and pe o med hei hea ea men . The esul s o he
he momagne iza ion measu emen s a e shown in Figu e 3.10. Acco ding o
Figu e 3.10, he ans o ma ion and magne ic beha iou o he hea ea ed
ibbon V3 co esponds o he mos desi able cha ac e is ics o he p esen
wo k.
86
Ribbons o Heusle - ype Magne ic Shape Memo y Alloys
Figu e 3.16: SEM c oss-sec ional iew o as-spun Ni46Mn31Co5Ga17Fe1 (le ) and SEM su ace image o he ibbon
shiny ace which was in con ac wi h Cu wheel ( igh ).
magne ocalo ic
3.3.3.2. T ans o ma ion cha ac e is ics
Figu es 3.17 and 3.18 show he he momagne iza ion cu es o bo h as-
spun and hea - ea ed ibbons unde low and high magne ic ields. All cu es
in hese wo igu es indica e M(H) anomaly ypical o a second o de magne ic
ansi ion om he pa amagne ic o he e omagne ic s a es in he ma ensi ic
phase, which means ha he Cu ie empe a u e (a abou 238 K) is below a
ma ensi ic ans o ma ion. No e a well-p onounced Hopkinson peak a low
magne ic ield. This ma e ial would no yield a subs an ial magne ic en opy
change (see equa ion (3)) since he magni ude o his change depends on he
cha ac e o he magne iza ion d op which is e y smea ed in Figu e 3.17. Thus,
his alloy is no sui able o he objec i es o his hesis.

87
Chap e 3
Figu e 3.17: The momagne iza ion cu es o Ni46Mn31Co5Ga17Fe1 ibbons in he as-spun and hea ea ed
s a es. Low magne ic ield cu es a e shown in mo e de ail in he inse .
Figu e 3.18: The momagne iza ion cu es o Ni46Mn31Co5Ga17Fe1 as-spun ibbons a di e en magne ic
ield.
3.3.4. Ni50Mn18.7Cu6.25Ga25
3.3.4.1. Composi ion and mic os uc u e
A nominal composi ion o Ni50Mn18.7Cu6.25Ga25 was also checked o ge
he ibbon exhibi ing me ged MT and Cu ie empe a u es. The ibbon wi h a
hickness o a ound 20μm was ab ica ed a 30 m/s o wheel speed. EDS
analysis e ealed ac ual composi ions o he as-spun ibbon and hea ea ed
one which a e shown in Table 3.8. Al hough he composi ions o as-spun and
88
Ribbons o Heusle - ype Magne ic Shape Memo y Alloys
HT ibbons a e qui e simila , bo h o hem a e di e en om he nominal
composi ion.
Table 3.8: Ac ual composi ion o as-spun and hea ea ed ibbons.
Sample
Ni (a %)
Mn (a %)
Cu (a %)
Ga (a %)
As-spun 30 m/s
51.1
15.9
6.7
26.3
HT ibbons
52.2
15.8
6.8
25.2
The c oss-sec ional mic os uc u es o bo h ibbons a e depic ed in Figu e
3.19 showing i egula shaped g ains. The ac u e su ace in he le image
e lec s mo e duc ile na u e o he ac u e han he one on he igh image.
Figu e 3.19: C oss-sec ional mic os uc u e o as-spun (le ) and hea ea ed ibbons ( igh ).
3.3.4.2. T ans o ma ion cha ac e is ics
The esul s o he momagne iza ion beha iou o he as-spun and hea
ea ed ibbons a low and high magne ic ield a e shown in Figu e 3.20. The
e ec o hea ea men on he cu es p esen ed in Figu e 3.20 is almos
negligible. Like in he case o ibbon om subsec ion 3.2.2.1, he dependences
e lec an o dina y e omagne ic ansi ion in he ma ensi ic s a e wi h Cu ie
empe a u e o abou 229 K, which means ha MT occu s a high empe a u es
in he pa amagne ic s a e. No e Hopkinson peaks a a low magne ic ield. The
second-o de na u e o his magne ic ansi ion and a e y smea ed cha ac e o
he M(T) cu es mean ha magne ocalo ic pe o mance o ma e ial should be
low, making his ibbons no sui able o he aim o he hesis.
89
Chap e 3
Figu e 3.20: The momagne iza ion cu es o as-spun and hea ea ed ibbons.
3.3.5. Ni50Mn18Cu5Ga25Fe2
3.3.5.1. Composi ion analysis
In o de o dec ease MT empe a u e and inc ease TCA, he ibbon wi h a
nominal composi ion o Ni50Mn18Cu5Ga25Fe2 was designed using he da a o
alloy om Subsec ion 3.2.2. The ac ual composi ion was de e mined as shown
in Table 3.9.
Table 3.9: Ac ual composi ion o as-spun ibbon.
Sample
Ni (a %)
Mn (a %)
Cu (a %)
Ga (a %)
Fe (a %)
As-spun 30 m/s
49.0
19.3
5.9
23.7
2.3
magne ocalo ic
3.3.5.2. T ans o ma ion cha ac e is ics
The momagne iza ion cu es a di e en magne ic ields a e shown in
Figu e 3.21. The M(T) dependence when cooling om high empe a u e
exhibi s i s anomaly p oduced by Cu ie empe a u e in he aus eni e (a abou
323 K), hen du ing u he cooling i shows a hys e e ic loop due o MT (a
abou 238 K) which shi s o he highe empe a u es unde magne ic ield.
These ea u es a e ypical o he e omagne ic Ni-Mn-Ga (FSMAs), exac ly
90
Ribbons o Heusle - ype Magne ic Shape Memo y Alloys
opposi e o he beha io s o MT in MMSMAs. The e o e his alloy does no
i o he objec i es o he p esen wo k.
Figu e 3.21: The momagne iza ion cu es a di e en magne ic ields.
3.4. NiMnIn MSMA SYSTEM
3.4.1. Ni45.2Mn36.7Co5.1In13.0
3.4.1.1. Composi ion analysis
I is well-known ha he MT and magne ic cha ac e is ics o NiMnIn-
based Heusle - ype o -s oichiome ic MMSMAs a e e y di icul o ep oduce
due o ex emely high sensi i i y o he composi ion a ia ion and o deg ee o
a omic o de . In he p esen wo k, we selec ed nominal composi ion o such
ype o alloy Ni45.2Mn36.7Co5.1In13.0 and p epa ed ibbon, which ac ual
composi ion is p esen ed in Table 3.10.
Table 3.10: Ac ual composi ion o as-spun ibbon.
Sample
Ni (a %)
Mn (a %)
Co (a %)
In (a %)
As-spun ibbon
46.8
35.5
5.5
12.2
91
Chap e 3
3.4.1.2. T ans o ma ion cha ac e is ics
The low- ield he momagne iza ion cu e o he as-spun ibbon,
p esen ed in Figu e 3.22, shows a well-p onounced MT and Cu ie empe a u e
o he e omagne ic ansi ion. MT occu s well below oom empe a u e wi h
he mal hys e esis o abou 50 K. The M(T) dependence o he HT ibbon in
his igu e shows a educed MT hys e esis, o abou 30 K, bu s ill i is oo la ge.
Mo eo e , MT is shi ed o low empe a u es, o abou 100 K. All hese ac o s
a e no in line wi h objec i es o he p esen wo k so his ma e ial is disca ded
o he u he in es iga ions.
Figu e 3.22: The momagne iza ion cu es o he as-spun and HT ibbons.

92
Ribbons o Heusle - ype Magne ic Shape Memo y Alloys
3.5. CONCLUSIONS
In his Chap e we ha e p epa ed a numbe o he ibbons ea u ing h ee
main classes o he Heusle - ype MSMAs. Thei basic cha ac e iza ion
( ans o ma ion beha iou and magne ic p ope ies) was mos ly pe o med by
he momagne iza ion measu emen s. Based on he esul s ob ained, he
ollowing ibbons we e selec ed o he p epa a ion o MMSMA powde s and
hei all- ound s udies: Mn42.5Ni40Co8Sn9.5, Mn48Ni35.5Sn8Co6.5Fe2,
Ni43Mn39Co7Sn11, Ni50Mn18.7Cu6.25Ga25.
93
Chap e 3
3.6. REFERENCES
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[2] D.Y. Cong, S. Ro h, L. Schul z, Magne ic p ope ies and s uc u al ans o ma ions in
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h ps://doi.o g/10.1016/j.ac ama .2012.06.034.
[3] E.C. Passamani, F. Xa ie , E. Fa e-Nicolin, C. La ica, A.Y. Takeuchi, I.L. Cas o,
J.R. P o e i, Magne ic p ope ies o NiMn-based Heusle alloys in luenced by Fe
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ans o ma ion beha io and adiaba ic magne ocalo ic e ec o Ni 50 Mn 35 In 15
ibbons, J. Alloys Compd. 748 (2018) 464–472.
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Cas illo-Villa, H. Flo es-Zúñiga, V.A. Che nenko, In luence o Fe doping and
magne ic ield on ma ensi ic ansi ion in Ni–Mn–Sn mel -spun ibbons, Ac a Ma e .
107 (2016) 9–16. h ps://doi.o g/10.1016/J.ACTAMAT.2016.01.041.
[6] P. Lázpi a, M. Sasmaz, E. Cesa i, J.M. Ba andia án, J. Gu ié ez, V.A. Che nenko,
Ma ensi ic ans o ma ion and magne ic ield induced e ec s in Ni42Co8Mn39Sn11
me amagne ic shape memo y alloy, Ac a Ma e . 109 (2016) 170–176.
h ps://doi.o g/10.1016/J.ACTAMAT.2016.02.046.
[7] Y. Wang, D. Salas, T.C. Duong, B. Medasani, A. Talapa a, On he as kine ics o B2
e L2 1 o de ing in Ni-Co-Mn-In me amagne ic shape memo y alloys, 781 (2019).
h ps://doi.o g/10.1016/j.jallcom.2018.12.034.
[8] V. Golub, V.A. L’ o , O. Salyuk, J.M. Ba andia an, V.A. Che nenko, Magne ism o
nano winned ma ensi e in magne ic shape memo y alloys, J. Phys. Condens. Ma e .
32 (2020) 313001. h ps://doi.o g/10.1088/1361-648X/ab7 69.
[9] R. Kainuma, Y. Imano, W. I o, Y. Su ou, H. Mo i o, S. Okamo o, O. Ki akami, K.
Oikawa, a Fuji a, T. Kanoma a, K. Ishida, Magne ic- ield-induced shape eco e y by
e e se phase ans o ma ion., Na u e. 439 (2006) 957–60.
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[10] T. K enke, E. Duman, M. Ace , E.F. Wasse mann, X. Moya, L. Manosa, A. Planes,
In e se magne ocalo ic e ec in e omagne ic Ni-Mn-Sn alloys, Na . Ma e . 4 (2005)
450–454. h ps://doi.o g/10.1038/nma 1395.
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[11] V.A. Che nenko, V.A. L’ o , E. Cesa i, J.M. Ba andia an, Fundamen als o
magne ocalo ic e ec in magne ic shape memo y alloys, 1s ed., Else ie B.V., 2019.
h ps://doi.o g/10.1016/bs.hmm.2019.03.001.
[12] C.O. Aguila -O iz, D. So o-Pa a, P. Ál a ez-Alonso, P. Lázpi a, D. Salaza , P.O.
Cas illo-Villa, H. Flo es-Zúñiga, V.A. Che nenko, In luence o Fe doping and
magne ic ield on ma ensi ic ansi ion in Ni-Mn-Sn mel -spun ibbons, Ac a Ma e .
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[13] P. Lázpi a, M. Sasmaz, E. Cesa i, J.M. Ba andia án, J. Gu ié ez, V.A. Che nenko,
Ma ensi ic ans o ma ion and magne ic ield induced e ec s in Ni42Co8Mn39Sn11
me amagne ic shape memo y alloy, Ac a Ma e . 109 (2016) 170–176.
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[14] B. Rod íguez-C espo, D. Salaza , S. Lance os-Méndez, V. Che nenko, De elopmen
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[15] V.K. Pecha sky, K.A. Gschneidne , Magne ocalo ic e ec om indi ec
measu emen s: Magne iza ion and hea capaci y, J. Appl. Phys. 86 (1999) 565–575.
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1
Chap e 4
Chap e 4
Powde s o Heusle – ype
Magne ic Shape Memo y
Alloys
102
Powde s o Heusle - ype magne ic shape memo y alloys
Figu e 4.4: Rie eld e inemen o he X- ays di ac og ams o cubic aus eni e in he as-spun ibbon (uppe le ), hea -
ea ed ibbons (uppe igh ), as-g ound powde (lowe le ) and hea - ea ed powde (lowe igh ).
4.2.1.3. T ans o ma ion cha ac e is ics
Figu e 4.5 shows he he momagne iza ion cu es o he as-g ound and
hea ea ed powde s. I is e iden ha he hea ea ed ibbon g inding p ocess
o ob aining he powde signi ican ly deg ades he ma ensi ic ans o ma ion
( ed cu e in Figu e 3.2 e sus black cu e in Figu e 4.5). In he Chap e 3, i
was demons a ed ha special hea ea men s can signi ican ly imp o e he
magne ic p ope ies. Consequen ly, he same hea ea men ou e is ollowed
o he powde , as shown in Figu e 4.5, whe e he ab up ma ensi ic
ans o ma ion is success ully achie ed.
In summa y, he M(T) dependencies enable us o de e mine he op imal
hea ea men egime o bo h ibbons (as discussed in chap e 3) and powde .

103
Chap e 4
Addi ionally, i has been expe imen ally demons a ed ha by using a hea
ea men a 1173 K o 60’ + quenching, i is easible o eco e he
ans o ma ion cha ac e is ics o he manually g ound hin ibbon in he o m
o powde wi h pa icle sizes well below 38 µm. This inding is highly
signi ican since, as p e iously men ioned, i is challenging o eplica e
ans o ma ion cha ac e is ics om bulk MMSMA in o i s powde o m. In he
nex chap e , his inding will be alida ed h ough a de ailed compa a i e s udy
o he ibbon and p in ed powde as he ink ille .
Figu e 4.5: The momagne iza ion cu es o Ni40Mn42.5Co8Sn9.5 powde wi h di e en hea ea men s.
4.2.2. Mn48Ni35.5Sn8Co6.5Fe2
4.2.2.1. T ans o ma ion cha ac e is ics
The g inding p ocess o his ibbon esul ed in a e y d ama ic e ec on
he ma ensi ic ans o ma ion o he powde . Acco ding o he
he momagne iza ion dependences, shown in Figu e 4.6, bo h he as- ecei ed
and hea - ea ed powde s show a e y smea ed MT and he educed alue o
104
Powde s o Heusle - ype magne ic shape memo y alloys
M(T) change a MT, ac o s which impeded us o conside his powde as
candida e o p in ing.
Figu e 4.6: The momagne iza ion dependence o he Mn48Ni35.5Sn8Co6.5Fe2 hea - ea ed powde . Inse shows he
esul s o as-g ound powde .
4.2.3. Ni43Mn39Co7Sn11
4.2.3.1. Composi ion and mic os uc u e
F om he se o ibbons p epa ed wi h his nominal composi ion, wo
alloys we e chosen. The i s one, V3(A1), was selec ed o a sys ema ic s udy
o he e ec s o hea ea men s, and he second one, V1(A2), was chosen o
in es iga e he composi ion’s e ec on magne ocalo ic p ope ies. Table 4.3
shows he esul s on ac ual composi ions (ob ained by EDS wi h an
ins umen al unce ain y o ±0.5 a .%).
Table 4.3: Ac ual composi ions o he wo alloys s udied.
Sample
Ni (a %)
Mn (a %)
Co (a %)
Sn (a %)
A1 (V3)
43.3
39.2
7.4
10.1
A2 (V1)
43.3
39.8
6.6
10.3
105
Chap e 4
4.2.3.2. T ans o ma ion cha ac e is ics
The empe a u e dependences o low- ield magne iza ion, M(T), as well as
calo ime ic cu es, p esen ed in Figu e 4.7 and Figu e 4.8, espec i ely, we e
used o de e mine cha ac e is ic ans o ma ion empe a u es, hys e esis o MT
and he Cu ie empe a u e o he s udied powde s. Bo h igu es show well-
p onounced e ec s o hea ea men s on he ans o ma ion beha iou , whe e
i can be obse ed ha hea ea men s p oduced shi s in cha ac e is ic
empe a u es and a educ ion o he he mal hys e esis o MT. The ma ensi ic
ans o ma ions and Cu ie empe a u es we e e i ied by DSC measu emen s,
whe e MT om he high- empe a u e aus eni ic o low- empe a u e ma ensi ic
phases and ice e sa a e accompanied by exo he mal and endo he mal e ec s,
espec i ely (Figu e 4.8). No ably, sample A2 p esen s abou wice la ge
maximum sa u a ion magne iza ion alue han A1, meaning ha he o me
alloy sa u a es a lowe ield han A1, possibly, due o aniso opic e ec s
induced by he ab ica ion me hod o powde s (c ys al ex u e o shape
aniso opy). A high magne ic ields, bo h samples show simila alues o he
maximum magne iza ion.
Figu e 4.7: Magne iza ion e sus empe a u e dependences o he hea - ea ed and as- ecei ed powde s a low magne ic
ield.
106
Powde s o Heusle - ype magne ic shape memo y alloys
Figu e 4.8: DSC cu es o he hea - ea ed and as- ecei ed powde s.
Ma ensi ic and aus eni ic ans o ma ion empe a u es and he Cu ie
poin , we e ex ac ed om bo h M(T) and DSC cu es. They a e summa ized
in Table 4.4. I is e iden om Table 4.4 ha all he ans o ma ion
empe a u es measu ed by DSC cu es co ela ed wi h hose ob ained om he
M(T) da a.
Table 4.4: T ans o ma ion empe a u es ob ained om he low magne ic ield magne iza ion cu es by he de i a i e
me hod / and om he posi ions o ex emums on DSC cu es o hea - ea ed and no-hea - ea ed powde s.
Powde
TC, K
TA, K
TM, K
A1 No HT
388 / 395
275 / 280
248 /242
A1 HT1
393 / 396
296 / 291
270 / 268
A1 HT2
391 / 398
296 / 293
273 / 272
A2 HT2
397 / 403
298 / 295
277 / 271
107
Chap e 4
Figu e 4.9: Magne iza ion e sus empe a u e dependences showing he ma ensi ic ans o ma ion e olu ion wi h he
di e en hea ea men s pe o med o he powde A1.
4.2.3.3. “Magne ic ield – empe a u e” phase diag ams o ma ensi ic
ans o ma ion
The magne isa ion beha iou o ma e ials a high magne ic ields is
equi ed o e alua e hei magne ocalo ic pe o mance. I is also impo an o
check he magne iza ion beha iou unde magne ic ields achie able by he
pe manen magne s, such as 1.5 T [3]. Figu e 4.10 shows he magne isa ion
e sus empe a u e dependences o he ou powde s a a ield o 1.5 T. As
can be no iced in his igu e ha he magne isa ion jump a MT, deno ed as
ΔM, is c i ically a ec ed by hea ea men s, being doubled o he alloys ha
unde wen a hea ea men wi h espec o he non-hea - ea ed one. As a
esul , ΔM equal o 110 Am2kg-1 was eco ded o H2HT2 powde , which is, o
ou knowledge, a eco d-b eaking alue o any MMSMAs powde s ye
desc ibed in he li e a u e. I is wo h no ing ha he size o ΔM di ec ly ela es
o he magne ocalo ic pe o mance o ma e ials. A mo e di ec analysis o he
magne ocalo ic pe o mance o he alloys can be ob ained om he analysis o

108
Powde s o Heusle - ype magne ic shape memo y alloys
he momagne isa ion, M(T), cu es measu ed unde di e en cons an
magne ic ields up o 5 T, which a e p esen ed in Figu e 4.11.
Following o he magne ic ield–induced shi o anomalies on M(T)
cu es ( hese anomalies a e p oduced by MT), one can ob ain phase diag ams
o “ma ensi ic and aus eni ic ans o ma ion empe a u es” as a unc ion o
he magne ic ield, ep esen ed in Figu e 4.12 o all he samples. In all cases,
he e is a nega i e linea dependence o he MT empe a u es wi h inc easing
magne ic ield. The slope o his dependence o he hea - ea ed powde s was
calcula ed o be –(5.0±0.2) K/T, whe eas TM slope o he sample A1 wi hou
hea - ea men shows a slope o –(6.3±0.1) K/T.
Figu e 4.10: Magne iza ion e sus empe a u e dependences o he s udied powde s measu ed unde 1.5 T magne ic
ield.
109
Chap e 4
Figu e 4.11: The momagne iza ion cu es a di e en magne ic ields o he s udied powde s.
Figu e 4.12: Phase diag ams “MT ans o ma ion empe a u es e sus magne ic ield” o all he powde s.
110
Powde s o Heusle - ype magne ic shape memo y alloys
4.2.3.4. Magne ocalo ic e ec
4.2.3.4.1. Magne ic ield-induced en opy change
Con en ional and in e se magne ocalo ic e ec s a e cha ac e ized by he
iso he mal en opy change, ∆𝑆𝑚(𝑇,𝐻), and/o adiaba ic empe a u e change,
∆𝑇𝑎𝑑(𝑇,𝐻) when a magne ic ield is applied o emo ed in he iso he mal
condi ions. A magne ic ield induced en opy change can be es ima ed using
Maxwell he modynamic ela ionships [4]. F om he measu ed M(T) cu es a
di e en magne ic ields (Figu e 4.11), one can calcula e he iso he mal en opy
change ∆𝑆𝑚(𝑇,H) as ollows:
∆𝑆𝑚(𝑇,𝐻)= 𝑆𝑚(𝑇,𝐻)−𝑆𝑚(𝑇,0)= 𝜇0∫(𝜕𝑀(𝑇,𝐻′)
𝜕𝑇 )𝑑𝐻′
𝐻
0 (1)
Figu e 4.13 shows he ∆𝑆𝑚(𝑇,H) plo s calcula ed by using cooling and hea ing
da a om Figu e 4.11 o he ou powde s s udied.
Figu e 4.13: Magne ic en opy change a di e en magne ic ields as a unc ion o empe a u e de i ed om
cooling/hea ing M(T) dependences shown in Figu e 4.11.
111
Chap e 4
Figu e 4.13 shows ha he hea - ea ed powde s exhibi alues o ∆𝑆𝑚,𝑚𝑎𝑥 ≈
35 J·kg-1·K-1 as de i ed om he analysis o hea ing M(T,H) cu es a 𝜇0∆𝐻 =
7 𝑇, whe eas o he non-hea - ea ed sample ∆𝑆𝑚,𝑚𝑎𝑥 ≈10 J·kg-1·K-1.
The ∆𝑆𝑚,𝑚𝑎𝑥 alues ob ained om he cooling M(T) cu es a e lowe han
hose ob ained om he hea ing ones due o a mo e smea ed cha ac e o he
o wa d MT in compa ison wi h he e e se MT. Fo example, hea ing cu es
a 𝜇0∆𝐻 = 2 T yield ∆𝑆𝑚,𝑚𝑎𝑥 ≈ 20 J·kg-1·K-1 o he hea ea ed powde A1; his
alue alls down o 12 J·kg-1·K-1 o cooling cu es a he same ield.
No ewo hy, he alues o ∆𝑆𝑚,𝑚𝑎𝑥 o he hea ea ed samples ob ained in he
p esen wo k a e compa able o hose o well-known magne ocalo ic ma e ials
unde simila applied ields, e.g., ~18.5 J·kg-1·K-1 o Gd5(Si2Ge2)[5], o
LaFe11.4Si1.6 ~19.4 J·kg-1·K-1 [6], o ~25.0 J·kg-1·K-1 o Ni40Co8Mn42.5Sn9.5 [7].
The e is a ema kable di e ence in en opy change be ween he hea -
ea ed and non-hea - ea ed powde s, as expec ed om he less ab up M(T)
cu e wi h a much smalle ΔM o he non-hea - ea ed powde in Figu e
4.13(a). Fo A1, he e is almos no di e ence in en opy change be ween HT1
and HT2, as well as be ween HT2 o bo h A1 and A2.
Figu e 4.14 shows a compa ison o ∆𝑆𝑚(T) dependences o he ou
samples unde ield o 1.5 T. As p e iously men ioned, he di e ence be ween
he wo hea ea men s o he A1 powde is negligible in he hea ing cu es,
whe eas in he cooling cu es, he HTA1 sample has a sligh ly highe ∆𝑆𝑚,𝑚𝑎𝑥
han HT2. Fo he non-hea - ea ed alloy ∆𝑆𝑚,𝑚𝑎𝑥 is abou h ee imes smalle
han he es o he samples.
118
Powde s o Heusle - ype magne ic shape memo y alloys
o de ed aus eni e. A iny M(T) anomaly ully disca ds obse a ion o any
essen ial MCE esponse a MT. The e o e, his powde is no sui able o he
goal o he hesis and will no be implemen ed o p in ing.
Figu e 4.22: The momagne iza ion cu es unde di e en magne ic ields o he as-milled powde . The zoomed-in low
ield cu e is shown in he inse .
4.4. CONCLUSIONS
In his chap e we ha e p epa ed powde om he ibbons ha we e
selec ed in he p e ious chap e . The basic cha ac e iza ion (composi ion,
ans o ma ion beha iou and magne ocalo ic e ec ) was mos ly pe o med by
he momagne iza ion measu emen s. Apa om he powde ed ibbons,
ano he powde made by gas a omiza ion was s udied and cha ac e ized. Based
on he esul s ob ained, he ollowing powde s we e selec ed o he p in able
magne ocalo ic ink p epa a ion: Mn42.5Ni40Co8Sn9.5 powde ed ibbons and gas-
a omized Ni49.8Mn36.6Sn13.6 powde .

119
Chap e 4
4.5. REFERENCES
[1] D. Na h, F. Singh, R. Das, X- ay di ac ion analysis by Williamson-Hall, Halde -
Wagne and size-s ain plo me hods o CdSe nanopa icles- a compa a i e s udy,
Ma e . Chem. Phys. 239 (2020) 122021.
h ps://doi.o g/10.1016/J.MATCHEMPHYS.2019.122021.
[2] V. Sánchez-Ala cos, J.I. Pé ez-Landazábal, V. Reca e, I. Lucia, J. Vélez, J.A.
Rod íguez-Velamazán, E ec o high- empe a u e quenching on he
magne os uc u al ans o ma ions and he long- ange a omic o de o Ni–Mn–Sn
and Ni–Mn–Sb me amagne ic shape memo y alloys, Ac a Ma e . 61 (2013) 4676–
4682. h ps://doi.o g/10.1016/J.ACTAMAT.2013.04.040.
[3] T. Go schall, K.P. Skoko , M. F ies, A. Taubel, I. Radulo , F. Scheibel, D. Benke, S.
Riegg, O. Gu leisch, Making a Cool Choice: The Ma e ials Lib a y o Magne ic
Re ige a ion, Ad . Ene gy Ma e . 9 (2019).
h ps://doi.o g/10.1002/aenm.201901322.
[4] V.K. Pecha sky, K.A. Gschneidne , Magne ocalo ic e ec om indi ec
measu emen s: Magne iza ion and hea capaci y, J. Appl. Phys. 86 (1999) 565–575.
h ps://doi.o g/10.1063/1.370767.
[5] V.K. Pecha sky, J. Gschneidne K. A., Gian Magne ocalo ic E ec in Gd5Si2Ge2,
Phys. Re . Le . 78 (1997) 4494–4497.
h ps://doi.o g/10.1103/PhysRe Le .78.4494.
[6] F.X. Hu, B.G. Shen, J.R. Sun, Z.H. Cheng, G.H. Rao, X.X. Zhang, In luence o
nega i e la ice expansion and me amagne ic ansi ion on magne ic en opy change
in he compound LaFe11.4Si1.6, Appl. Phys. Le . 78 (2001) 3675–3677.
h ps://doi.o g/10.1063/1.1375836.
[7] B. Rod íguez-C espo, D. Salaza , S. Lance os-Méndez, V. Che nenko, De elopmen
and magne ocalo ic p ope ies o Ni(Co)-Mn-Sn p in ing ink, J. Alloys Compd. 917
(2022) 165521. h ps://doi.o g/10.1016/j.jallcom.2022.165521.
[8] K.A. Gschneide , Recen de elompen s in magne ic e ige a ion, 317 (1999) 69–76.
h ps://doi.o g/10.4028/www.scien i ic.ne /MSF.315-317.69.
[9] F. Scheibel, C. Lauho , P. K ooß, S. Riegg, N. Somme , D. Koch, K. Opel , H. Gu e,
O. Volko a, S. Böhm, T. Niendo , O. Gu leisch, Addi i e manu ac u ing o Ni-Mn-
Sn shape memo y Heusle alloy – Mic os uc u e and magne ic p ope ies om
powde o p in ed pa s, Ma e ialia. 29 (2023).
h ps://doi.o g/10.1016/j.m la.2023.101783.
[10] P. Lázpi a, M. Sasmaz, E. Cesa i, J.M. Ba andia án, J. Gu ié ez, V.A. Che nenko,
Ma ensi ic ans o ma ion and magne ic ield induced e ec s in Ni42Co8Mn39Sn11
me amagne ic shape memo y alloy, Ac a Ma e . 109 (2016) 170–176.
h ps://doi.o g/10.1016/j.ac ama .2016.02.046.
1
Chap e 5
Chap e 5
Ink P oduc ion and
2D – 3D p in ing
123
Chap e 5
Chap e 5
Design and Fab ica ion o No el Me allic
P in able Ma e ials
5.1. 2D AND 3D PRINTING OF COMMERCIAL POWDERS
5.1.1. Technique alida ion
This is he las chap e o he hesis and he one ha con ains i s global
objec i e: To de elop a new 2D-3D p in ing echnique and he implemen a ion
o he selec ed powde s o p in ac ual magne ocalo ic 2D-3D s uc u es.
The i s s ep o me allic 2D-3D p in ing is o elabo a e a ou e o
de eloping p ope inks ha a e sui able o p in ing high-quali y s uc u es wi h
good mechanical p ope ies, uni o m laye g ow h and high numbe o
p in able laye s. Fo de eloping such ou e, comme cial powde s we e used as
he i s s ep, since hey a e widely a ailable in he labo a o y allowing o make
a sys ema ic s udy o he p in ing limi a ions, op imiza ion, e c. Then, a e
es ablishing he ou e o p in ing quali y s uc u es, he echnique will be
implemen ed o he p epa ed magne ocalo ic powde s, a ailable in lowe
quan i y.
The main challenge o bo h 2D sc een-p in ing and 3D ex usion p in ing
echniques is o de elop a p ope ink so he p in ing esul is success ul. The
ink is made o h ee elemen s:
1) Me allic ille
2) Ma ix
3) Dissol en
The main pa ame e ha con ols he p in ing quali y is he iscosi y. Fo
sc een 2D p in ing he equi emen s o he ink a e no ha s ic , whe eas o

124
Ink P oduc ion and 2D – 3D P in ing
ex usion 3D p in ing he equi emen s a e mo e sensi i e and, apa om
p ope iscosi y, he ille /ma ix olume ic p opo ion is also c ucial.
5.1.2. Sea ching o a binde and sol en s o eco- iendly app oach using
me allic powde as ille
Cu en polyme p in ing me hods in ol e he use o chemical sol en s
and syn he ic polyme s. Also, high p in ing empe a u e is equi ed (220ºC o
PLA). Since ou aim is o ind eco- iendly app oach, we need o eplace hose
ma e ials by en i onmen ally iendly al e na i es. In ou case, he syn he ic
polyme is going o be eplaced by h ee al e na i es: (i) Silk, (ii) Collagen, and
(iii) Cellulose de i a i e. All o hese al e na i es a e ound in na u e so hey a e
widely a ailable na u al sou ce o aw ma e ials. The chemical sol en is going
o be eplaced by deionized wa e .
5.1.2.1. Silk-based ink
Once he silk is dissol ed in wa e , he p opo ion o wa e is abou 95%
so he polyme con en is oo low o sus aining he powde o be p in ed. The
p in ing es s esul ed in a sp ead o he ilamen ex uded losing i s o iginal
shape seconds a e he deposi ion in he subs a e, making his polyme no
sui able o 3D p in ing.
5.1.2.2. Collagen-based ink
Simila ly o he silk-based ink, he collagen con en a e i is dissol ed is
qui e low o being able o p in me allic powde s, esul ing in a sp ead o he
ilamen in he same manne as silk inks.
5.1.2.3. Cellulose-based ink
The Cellulose de i a i e ha we a e going o use is he Hyd oxyp opil
Cellulose since i has a good p ocessabili y and has been p o en o ha e a good
ilm o ming capaci y. In his case he polyme p opo ion, once is dissol ed in
wa e , can be uned by inc easing o high pe cen age. P in ing es s e ealed a
125
Chap e 5
consis en deposi ed ilamen s ha allow o p in uni o m laye s, making his
polyme he bes op ion o he aim o he hesis.
5.1.3. Comme cial powde s and ink pa ame e s
Fo me allic ille , a ious powde s a ailable in he labo a o y we e used.
The i s app oach was o use a powde ha is widely a ailable and ha has e y
simila densi y compa ed o he magne ocalo ic powde s (nea 8 g/cm3) in
o de o implemen he ou e o magne ocalo ic powde s. Hence, an i on
powde was selec ed o his pu pose. In addi ion, a ious es s we e pe o med
using Aluminium (Al) and Silicon (Si) powde s. Al hough hese powde s ha e
oughly 1/3 o I on densi y he p in ing o hese ma e ials may p o ide a be e
e inemen o he p in ing echnique.
Se e al inks we e p epa ed o es ing, i s wi h he sc een-p in e and
hen in he ex usion p in e . The me allic/cellulose weigh pe cen age a ied
om 85% o 95% and he iscosi y is con olled en i ely by he wa e con en
o he ink, ha is, o a ixed me allic pe cen age he wa e con en was a ied
in a sea ch o he bes p in ing esul . The weigh pe cen age canno be
inc eased a bi a ily o all he powde s used since he olume ic pe cen age o
he polyme needs o be abo e ce ain alue o sus ain he en i e powde .
In he case o I on 85% w . he wa e quan i y was a ied om 45% o
80% in olume (25% o 40% in weigh ) and he bes esul was 48%Vol. o
28%w (Table 5.1). Fo I on 92.5% w . he wa e quan i y was a ied om 40%
o 60% in olume (15% o 30% in weigh ) ha ing he bes esul s co esponding
o 51%Vol. o 22%w .
Aluminium ink was ound o be op imal wi h wa e con en o 23%Vol.
o 40%w ., a p opo ion ha was op imized a e a ying he wa e con en
om 15% o 35% in olume (o 30% o 55% in weigh ). Fo Silicon ink, he
wa e quan i y was a ied om 35% o 55%Vol. (27% o 52% in weigh ) and
he op imal p opo ion was ound o be 47%Vol. o 37%w (Table 5.1).
126
Ink P oduc ion and 2D – 3D P in ing
Table 5.1: Selec ed inks p epa ed o p in ing using comme cial powde s. The p opo ion o each cons i uen is lis ed
bo h in mass ac ion and in olume ac ion.
Ink
Cons i uen
Densi y
(g/ml)
Mass ac ion
(%)
Volume
ac ion (%)
Ink 1
Fe 85% w .
Fe powde (𝜙≤10 𝜇𝑚)
7.9
62
14
Deionized wa e
1.0
28
48
HPC
0.5
10
38
To al
1.7
100
100
Ink 2
Fe 92.5% w .
Fe powde (𝜙≤10 𝜇𝑚)
7.9
72
21
Deionized wa e
1.0
22
51
HPC
0.5
6
28
To al
2.4
100
100
Ink 3
Al 85% w .
Al powde (𝜙≤45 𝜇𝑚)
2.7
51
24
Deionized wa e
1.0
40
52
HPC
0.5
9
23
To al
1.3
100
100
Ink 4
Si 85% w .
Si powde (𝜙≤106 𝜇𝑚)
2.3
54
29
Deionized wa e
1.0
37
47
HPC
0.5
9
24
To al
1.3
100
100
Table 5.2: D ied ink pe cen ages.
Ink
Cons i uen
Densi y
(g/ml)
Mass ac ion
(%)
Volume
ac ion (%)
Ink 1
Fe 85% w .
Fe powde (𝜙≤10 𝜇𝑚)
7.9
85
27
HPC
0.5
15
73
To al
2.5
100
100
Ink 4
Fe 92.5% w .
Fe powde (𝜙≤10 𝜇𝑚)
7.9
92.5
45
HPC
0.5
7.5
55
To al
3.7
100
100
Ink 3
Al 85% w .
Al powde (𝜙≤45 𝜇𝑚)
2.7
85
51
HPC
0.5
15
49
To al
1.6
100
100
Ink 2
Si 85% w .
Si powde (𝜙≤106 𝜇𝑚)
2.3
85
55
HPC
0.5
15
45
To al
1.5
100
100
127
Chap e 5
Table 5.1 shows he selec ed inks om comme cial powde s wi h he
p opo ions o each cons i uen in mass and olume pe cen age bu he p in ed
s uc u e will con ain only he polyme and he me allic powde , so i is o g ea
in e es o know he mass and olume ic p opo ion o polyme e sus me allic
powde in he d ied inks, see Table 5.2.
5.1.4. P in ing comme cial powde s
5.1.4.1. Sc een-p in ing
The i s app oach o ink es ing was done by 2D sc een-p in ing. In his
echnique 16 x 8 mm ec angle shaped chips we e p in ed by applying 1 and 10
laye s o ma e ial o inc ease he magne ic con en and o compa ison (see
Figu e 5.2). To modi y he su ace ension o he ink and imp o e i s we abili y,
he su ace ac i e agen BYK-348 was added in a p opo ion o 3 - 5 μl/ml.
Se e al inks we e p epa ed o sc een-p in ing by a ying he p opo ions o
ille ma e ial, binde and wa e . Th ee weigh ac ions o me allic powde ,
namely, 60 w %, 75 w % and 85 w % we e e alua ed. Fo he ink wi h he 85
w % o ille he amoun o wa e was a ied in o de o ge op imal iscosi y
main aining he highes possible quan i y o he me allic powde . I was ound
ha he bes -wo king ink should con ain 85 w % o powde and 15 w % o
HPC, co esponding o he powde /dissol en p opo ion o 1 g/0.45 mL.
This p opo ion esul ed in an op imal ink iscosi y o he sc een-p in ing
(1000–10,000 cP).
Figu e 5.1: Schema ic ep esen a ion o sc een-p in ing se up.