1
E ec o Gd on he de i i ica ion and magne ic p ope ies o
[(Fe0.6Co0.4)0.75Si0.05B0.20]96-xNb4Gdx me allic glasses
J. To ens-Se a1,*, B. Kus o 1, P. B una2,3,4
1Depa amen de Física, Uni e si a de les Illes Balea s, C a. de Valldemossa km 7.5, 07122,
Palma de Mallo ca. Spain
2Depa amen de Física, Uni e si a Poli ècnica de Ca alunya, Ba celonaTech (UPC), A . Edua d
Ma is any 16, 08019 Ba celona, Spain.
3Ins i u de Tècniques Ene gè iques (INTE), A . Diagonal 647, 08028 Ba celona, Spain
4Ba celona Resea ch Cen e in Mul iscale Science and Enginee ing, Uni e si a Poli ècnica de
Ca alunya. Ba celonaTech (UPC), A . Edua d Ma is any 16, 08019 Ba celona, Spain
Abs ac
The in luence o mic oalloying wi h Gd on he he mal s abili y, c ys alliza ion and magne ic
p ope ies o [Fe0.6Co0.4)0.75Si0.05B0.20]96-xNb4Gdx (x=0,1,2,5) me allic glasses was examined.
Va ious glass- o ming abili y c i e ia we e calcula ed based on he mal cha ac e is ics
ob ained by di e en ial scanning calo ime y o mel -spun ibbons and compa ed o he
maximum size achie ed o he alloys ia di ec od cas ing. Al hough he modynamic-based
c i e ia p edic la ge glass- o ming abili y o he alloy wi h highe Gd con en , x=5 alloy
showed he lowes abili y o o m ull glassy ods. The s uc u al e olu ion a e i s
c ys alliza ion e en was analyzed by x- ay di ac ion and T ansmission Mössbaue
spec oscopy. The obse ed changes in he p ecipi a ed phases in x=5 alloy compa ed o
x=0,1,2 alloys a e associa ed o he dec ease in he glass- o ming abili y. The o ma ion o
* j. o [email protected]
2
phases o he han (FeCo)23B6 phase in x=5 alloy is esponsible o no achie ing ully glassy
ods. Addi ionally, he magne ic p ope ies o glassy ibbons a e signi ican ly a ec ed by he
addi ion o Gd. Sa u a ion magne iza ion and Cu ie empe a u e dec ease as Gd con en
inc eases.
Keywo ds: Bulk Me allic Glasses; Mössbaue Spec oscopy; Glass- o ming abili y;
C ys alliza ion
1. In oduc ion
Fe-based bulk me allic glasses a e called o eplace c ys alline alloys in many applica ions
due o hei excellen unc ional p ope ies. Despi e hese p omising p ope ies, he la ge-
scale indus ial p oduc ion has only been possible in o m o ibbons o abou 50 µm o pieces
p oduced om amo phous powde s by powde me allu gy. Many comme cial applica ions
equi e shapes o mechanical cha ac e is ics ha only bulk me allic glasses can achie e.
Since Inoue and co-wo ke s [1] cas he i s Fe-based bulk me allic glass (wi h a hickness
la ge han 1 mm) in 1995, many di e en alloy amilies ha e been epo ed in li e a u e
ha ing high glass- o ming abili y (GFA) combined wi h excellen unc ional p ope ies like
high s eng h, high co osion esis ance and excellen so magne ic p ope ies such as low
coe ci i y, high magne ic pe meabili y and low co e losses [2–8]. In ecen yea s,
conside able e o s ha e been di ec ed owa ds he p oduc ion o millime e -sized ull glassy
alloys while main aining hei unc ional p ope ies. Despi e hese ex ensi e e o s, se e al
challenges pe sis and emain unsol ed. In a ecen e iew, Li e al. [2] poin ed o he
ollowing issues ha would dese e u he esea ch o a u u e applica ion and
comme cializa ion o Fe-based bulk me allic glasses: a) ob en ion o la ge -sized Fe-based
BMGs; b) imp o ing he ab ica ion me hods; c) enhancemen o oom empe a u e
3
oughness; d) a aining highe sa u a ion magne iza ion; and e) cos educ ion h ough he use
o indus ial aw ma e ials and low acuum condi ions.
In many alloys i has been obse ed ha he la ge glass- o ming abili y is di ec ly ela ed o
he o ma ion o complex c ys alline s uc u es wi h a la ge uni cell as a p ima y
c ys alliza ion p oduc [9,10]. The high esis ance o c ys alliza ion om he unde cooled
liquid helps o s abilize he amo phous s uc u e. In pa icula , Fe23B6 is he esponsible o
he supe io GFA in (Fe,Co,Ni)-Si-B-Nb alloys [6,11–16], which has been epo ed o display
excellen so magne ic p ope ies, as well as, high mechanical s eng h. Howe e , he la ges
dimension success ully cas in ully amo phous s a e emains below 8 mm, which does no
mee indus ial expec a ions [9]. Many s a egies ha e been used wi h he aim o enhance he
GFA. Aside om o he s a egies like di e en cas ing echniques o p ocessing ou es
[17,18], he app op ia e addi ion o small amoun s o di e en elemen s (mic oalloying) has
been p o en o be e ec i e in enhancing bo h glass- o ming abili y and unc ional p ope ies
[19–28]. The p esence o hese alloying elemen s p oduce changes in he local a omic
con igu a ion [29] and c ea e nanoscale s uc u al he e ogenei ies [30] which a ec glass-
o ming abili y, c ys alliza ion and unc ional p ope ies o BMGs. Howe e , he
mechanisms unde lying his e ec a e no ully unde s ood. Li e al. [2] highligh ed his issue
as key poin ha should be sol ed.
In some ecen pape s we ha e analyzed he ole o di e en alloying elemen s on he GFA
and c ys alliza ion pa h o Fe-B-Si-Nb-based alloys. The use o T ansmission Mössbaue
Spec oscopy (TMS) has enabled de ail acking o he changes in he en i onmen s o Fe
a oms du ing he de i i ica ion o he glass and o he de e mine he hype ine pa ame e s o
he Fe23B6 phase o med in hese alloys, which a e in luenced by he alloying elemen s.
Mo eo e , his echnique has allowed o quan i a i e analysis o he pe cen age o Fe a oms
4
o ming his phase and di e en ia ion be ween a ious en i onmen s gene a ing dis inc
hype ine magne ic ields [24,25]. The ole o a e ea h (RE) mic oalloying elemen s is o
pa icula in e es due o hei impac on bo h glass o ma ion and magne ic p ope ies o
BMGs. RE possess a magne ic momen o igina ed om he localized 4 elec ons. Se e al
s udies ha e demons a ed ha he in e ac ion be ween hese 4 elec ons and he 3d elec ons
om Fe a oms nega i ely a ec he so magne ic p ope ies o Fe-B-Si-Nb-(Tb,Dy) BMGs,
as well as, de e io a e hei p ope ies as glass o me s [22,23]. Consequen ly, he use o RE
as mic oalloyan is s ill con o e sial. In he p esen s udy, ou pu pose is o shed some ligh
on he ole played by Gd on he glass- o ming abili y, he de i i ica ion p ocess and
magne ic p ope ies o [(Fe0.6Co0.4)0.75Si0.05B0.20]96-xNb4Gdx (x=0,1,2,5) alloys. Se e al
c i e ia p edic ing GFA and c i ical hickness ha e been calcula ed compa ed o he c i ical
diame e ob ained expe imen ally by di ec cas ing o he alloys. T ansmission Mössbaue
spec oscopy, complemen ed by X- ay di ac ion, ha e been employed o elucida e he
s uc u al changes in he amo phous alloys upon hea ea men . The s udy e eals ha
di e en phases p ecipi a e depending on Gd con en o he alloy, which is linked o he
dec ease in he glass- o ming abili y. Gd also has a de imen al e ec on magne ic p ope ies.
2. Expe imen al p ocedu e
Ribbons o [(Fe0.6Co0.4)0.75Si0.05B0.20]96-xNb4Gdx (x=0,1,2,5) composi ions ( om now on
designed as Gd0, Gd1, Gd2 and Gd5, espec i ely) wi h a hickness o 50 µm and a wid h o
4 mm we e p epa ed by single- olle mel spinning a a linea speed o 40 m/s om
polyc ys alline mas e alloys. The p ocess o he p epa a ion o mas e alloys can be ound
elsewhe e [24]. All he ibbons show a egula and con inuous shape excep x=5 alloy which
is p oduced in o m o lakes o 2-3 cm. F om x=5 alloy, ods o diame e 1.5 mm and 2 mm
5
we e ab ica ed by injec ion cas ing in a wa e -cooled coppe mold unde p o ec i e high-
pu i y a gon a mosphe e. The s uc u e o he as-cas ibbons and ods, as well as, he
e olu ion o he s uc u e o he ibbons subjec ed o a di e en he mal ea men s was
s udied using a Philips PW 1050 x- ay di ac ome e (XRD) wi h Co Kα adia ion (λ=1.7888
Å) in B agg-B en ano geome y. The he mal cha ac e iza ion o he amo phous ibbons was
pe o med by di e en ial scanning calo ime y (DSC) using a NETZSCH DSC 404 a a
hea ing a e o 20 K/min unde a low o high pu i y A . T ansmission Mössbaue spec a
we e ob ained a oom empe a u e and p essu e using a con en ional cons an accele a ion
spec ome e wi h a 25 mCi sou ce o 57Co in Rh ma ix. The spec a we e eco ded in a
mul ichannel analyze using a eloci y ange o ±7.5 mm/s and we e subsequen ly i ed wi h
he NORMOS so wa e [31], conside ing one magne ic hype fine field dis ibu ion wi h
linea co ela ion be ween he isome shi and he magne ic field o he amo phous
s uc u es and one o mo e disc e e spec a (single s, double s o sex e s) o he c ys alline
phases. The i ed pa ame e s a e he isome shi (δ), always exp essed ela i e o he isome
shi o he bcc-Fe measu ed a oom empe a u e and p essu e, he quad upole spli ing (Δ)
and he hype ine magne ic ield (BHF). In all cases he a ea exp essed in % co esponds o
he ac ion o Fe a oms in a pa icula en i onmen wi h espec o he o al amoun o Fe
a oms and he magni udes inside pa en heses a e he s anda d de ia ion.
Sa u a ion magne iza ion o he as-spun ibbons was ob ained om he Magne iza ion s.
applied ield (M-H) hys e esis loops eco ded wi h a Lakesho e 735 ib a ing sample
magne ome e (VSM) a 305 K, o magne ic ields up o 1.5 T. The Cu ie empe a u e, TC,
o he amo phous ibbons was de e mined om magne iza ion s empe a u e cu es, M(T),
eco ded using a home-made Fa aday magne ome e . Samples subjec ed o a fixed magne ic
field o 5.5 kOe we e hea ed a a cons an a e o 20 K/min up o he expe imen al limi o
6
he de ice, 973 K. Expe imen al da a was hen analyzed using he me hod p oposed by
He ze [32]. Close o TC, he sa u a ion magne iza ion can be w i en as:
𝑀𝑀𝑆𝑆(𝑇𝑇) = 𝑀𝑀(0) �1−𝑇𝑇
𝑇𝑇𝑐𝑐�0.36 (1)
The expe imen al M(T) cu es a e plo ed as 𝑀𝑀𝑠𝑠10.36
� s T and he Cu ie empe a u e is
conside ed he empe a u e whe e 𝑀𝑀𝑠𝑠10.36
� de ia e om linea i y. The coe ci i y Hc was
measu ed using a Foe s e Coe cima unde an applied ield high enough o sa u a e he
samples. All magne ic p ope ies we e measu ed unde DC magne ic ield.
3. Resul s and discussion
3.1 Glass o ma ion and he mal s abili y
Figu e 1(a) p esen s he X- ay di ac ion (XRD) pa e ns o he as-spun ibbons, all o which
exhibi a b oad halo indica i e o amo phous s uc u es.
Figu e 1. (a) XRD pa e ns o as-spun ibbons o all ou alloys, (b) XRD pa e ns o he
as-cas ed ods o diame e d=1.5 and d=2 mm o Gd5 alloy.
7
Figu e 2 displays he DSC he mog ams eco ded a a hea ing a e o 20 K/min o all ou
alloys. In Figu e 2(a), he de i i ica ion pa hway o Gd5 alloy is compa ed o Gd0, Gd1, and
Gd2 ones, al eady published in [24] and included in he plo o assis he eade . DSC cu es
a e cha ac e ized by an endo he mic change ypical o he glass ansi ion and mul iple
exo he mic peaks. Gd5 alloy exhibi s a mo e complex c ys alliza ion pa h, wi h a leas h ee
o e lapping peaks du ing he ini ial c ys alliza ion s age, ollowed by wo addi ional peaks
a highe empe a u es in con as by he h ee dis inc c ys alliza ion peaks ound in Gd0,
Gd1, and Gd2 alloys. The co esponding alues o glass ansi ion empe a u e (Tg), onse
c ys alliza ion empe a u e (Tx), and peak empe a u e (Tp1, Tp2 and Tp3) a e lis ed in Table 1.
Glass ansi ion empe a u e does no show a mono onous inc ease wi h he amoun o Gd
p esen in he alloy. The addi ion o 1% o Gd o he alloy dec eases he glass ansi ion
empe a u e in espec o he Gd- ee alloy (Gd0), ye his empe a u e inc eases again wi h
la ge Gd alloys. On he con a y, he onse c ys alliza ion empe a u e is shi ed d ama ically
o highe empe a u es wi h he addi ion o Gd. Consequen ly, he supe cooled liquid ange
(SLR), de ined as ∆𝑇𝑇𝑥𝑥=𝑇𝑇𝑥𝑥−𝑇𝑇𝑔𝑔 , shows a la ge enhancemen , om he 37 K ound in Gd0
alloy o 60 K in Gd5. The i s wo c ys alliza ion s ages also show a shi owa ds la ge
empe a u es wi h he Gd con en . Howe e , he hi d one seems o be educed in Gd5 alloy
and does no ollow he same end. The mel ing and he subsequen solidi ica ion o he
alloys can be ound in igu e 2(b). The inc ease o Gd in he composi ion expands he
empe a u e ange in which he coexis ence o solid and liquid phases is ound. The
cha ac e is ic mel ing empe a u e (Tm), liquidus empe a u e (Tl) and solidus empe a u e
(Ts), o all alloys a e also lis ed in Table 1. The addi ion o Gd dec eases he s abili y o he
liquid shown by a shi o liquidus and solidus empe a u es o la ge alues. Also, he
8
di e en mel ing peaks end o be mo e sepa a ed as mo e Gd is in he composi ion. This
indica es ha he Gd is mo ing he alloys a om he eu ec ic poin .
Figu e 2. DSC he mog ams o as-spun ibbons showing (a) he c ys alliza ion and (b) he
mel ing and solidi ica ion, o all ou alloys. Cha ac e is ic empe a u es a e signed by an
a ow.
Table 1. Glass ansi ion empe a u e (Tg); onse empe a u e o he i s c ys alliza ion peak
(Tx); supe cooled liquid ange (ΔTx); i s , second and hi d c ys alliza ion peak empe a u es
(Tp1, Tp2, Tp3); mel ing empe a u e (Tm); liquidus empe a u e (Tl); solidus empe a u e (Ts)
and p ima y c ys alliza ion en halpy (ΔHx1), o all he s udied alloys.
The glass o ming abili y can be di ec ly measu ed by wo pa ame e s: he c i ical cooling
a e (Rc) and he maximum diame e (o dimension) o ully amo phous alloy (dc). Howe e ,
hese magni udes a e di icul o measu e and depend s ongly on he ab ica ion me hod. In
T
g
(K)
T
x
(K)
ΔT
x
(K)
T
p1
(K)
T
p2
(K)
T
p3
(K)
T
m
(K)
T
l
(K)
T
s
(K)
ΔH
x1
(J/g)
Gd0
821
860
39
869
981
1062
1326
1421
1368
33±2
Gd1
815
867
52
879
1039
1110
1318
1410
1376
30±2
Gd2
833
894
56
903
1047
1127
1328
1452
1431
37±2
Gd5
907
967
60
973
1072
1097
1340
1451
1425
51±2
9
he li e a u e se e al c i e ia based on he cha ac e is ic empe a u es easily measu able by
he mal analysis ha e been p oposed o p edic he glass o ming abili y o he alloys and
many pape s a e de o ed o e alua ing which is he bes c i e ion [33,34]. The supe cooled
liquid ange (SLR) is commonly used o e alua e he s abili y o he glass ( esis ance o
c ys alliza ion), whe eas he educed glass ansi ion empe a u e in oduced by Tu nbull
[35], de ined as T g=Tg/Tl, indica es ha he smalle is he in e al be ween glass ansi ion
and liquidus empe a u e, he easie is o a oid nuclea ion o c ys alline phases du ing
cooling. Mo e ecen ly, he new c i e ia inco po a e bo h conside a ions and basically depend
on he h ee cha ac e is ic empe a u es – Tg, Tx and Tl. In o de o es some o hese c i e ia
in ou alloys, we ha e calcula ed he alues o he 𝛼𝛼=𝑇𝑇𝑥𝑥
𝑇𝑇𝑙𝑙 [36], 𝛽𝛽=�𝑇𝑇𝑥𝑥
𝑇𝑇𝑔𝑔+𝑇𝑇𝑔𝑔
𝑇𝑇𝑙𝑙� [36], 𝛾𝛾=𝑇𝑇𝑥𝑥
𝑇𝑇𝑔𝑔+𝑇𝑇𝑙𝑙
[37], 𝛾𝛾𝑚𝑚=2𝑇𝑇𝑥𝑥−𝑇𝑇𝑔𝑔
𝑇𝑇𝑙𝑙 [34], 𝜔𝜔=2𝑇𝑇𝑥𝑥−𝑇𝑇𝑔𝑔
𝑇𝑇𝑙𝑙+𝑇𝑇𝑥𝑥 [38], and 𝜛𝜛=(𝑇𝑇𝑥𝑥−𝑇𝑇𝑔𝑔)𝑇𝑇𝑔𝑔𝑇𝑇𝑥𝑥
(𝑇𝑇𝑙𝑙−𝑇𝑇𝑥𝑥)3 [39] c i e ia om he measu ed
cha ac e is ic empe a u es and compa ed hem o he maximum diame e o he ully
amo phous od cas ed expe imen ally. We ha e also de e mined he c i ical cooling a e (Rc)
and he c i ical sec ion hickness (Zc) wi h he empi ical o mula p oposed by Lu [37]: 𝑅𝑅𝑐𝑐=
5.1 × 1021exp(−117.19𝛾𝛾) and 𝑍𝑍𝑐𝑐= 2.8 × 10−7exp(41.7𝛾𝛾) , espec i ely. In a ecen
pape we discussed he in luence o some mino addi ions o he glass o ming abili y o Fe-
based BMGs. The e, we showed ha ods o composi ions Gd0 and Gd2 can be ob ained in
ully amo phous s a e up o 1.5 mm o diame e , bu i was no possible o Gd1 alloys [24].
To comple e his s udy and unambiguously de e mine i his a e ea h addi ion may be
bene icial o GFA o no , 1.5 and 2 mm diame e ods o Gd5 composi ion ha e been cas .
The XRD measu emen s (Figu e 1(b)) show ha none o hem is ully glassy. Some
conclusions can be ex ac ed om he compa ison be ween he GFA c i e ia and he esul s
o he cas ing. Bo h SLR and educed glass ansi ion c i e ia canno desc ibe he GFA o ou
16
a e age magne ic hype ine ield o he hype ine ield dis ibu ion. a % Fe co esponds o
he a omic pe cen age o Fe a oms in each phase.
Phase
As-quenched
1s . ans.
Amo phous
δ (mm s-1)
0.03 (2)
0.02 (1)
Δ (mm s-1)
-0.04 (1)
0.01 (1)
BHFa g(T)
18.1 (1)
20.0 (2)
a .% Fe
100
87.0 (5)
Fe2Nb
δ (mm s-1)
-
-0.20 (1)
Δ (mm s-1)
-
0.34 (3)
a .% Fe
-
5.5 (5)
ε-FeSi
δ (mm s-1)
-
0.18 (1)
Δ (mm s-1)
-
0.46 (2)
a .% Fe
-
7.5 (5)
Figu e 4. Expe imen al Mössbaue spec a (blue do s) and hei i ( ed line) o he Gd5
composi ion in he as-quenched s a e (a), a e he i s ans o ma ion (c) and in he ully
c ys alline s a e (d). The colo ed lines co espond o he se e al subspec a used o he
i ing and explained in ex . (b) The hype ine ield dis ibu ions o he as-quenched ibbon
and a e he i s ans o ma ion. The inse shows he e olu ion o he a e age hype ine
ield o he as-quenched ibbons o all he composi ions.
17
Table 4. Hype ine pa ame e s o he ully c ys alline Gd5 sample. δ is he isome shi , Δ is
he quad upole spli ing and BHF is he magne ic hype ine ield in T. a % Fe co esponds
o he a omic pe cen age o Fe a oms in each phase.
bcc-(FeCo) Fe23B6 FeB - I FeB - II Fe3B – I Fe3B – II Fe2Nb ε-FeSi
δ (mm s
-1
)
0.01 (1)
-0.26 (1)
0.1 (1)
0.07 (1)
0.15
-0.04 (2)
-0.1
0.28
Δ (mm s-1) 0.02 (1) 0.4 (1) 0.05 (2) -0.3 (1) -0.2 (2) 0.10 (3) 0.56 0.49 (3)
BHF (T)
36.7 (1)
16.6 (1)
9.8 (1)
13.1 (1)
21.4 (1)
25.5 (1)
-
-
a .% Fe 30.7 (1) 10.6 (1) 12.2 (1) 16.9 (1) 15.2 (1) 6.5 (1) 5.2 (1) 2.7 (1)
Figu e 5. Va ia ion o he a omic pe cen age o he di e en phases in he ully c ys alline
samples. bcc-(FeCo) and (FeCo)23B6 include he co esponding Co- ee phases.
3.3 Magne ic p ope ies
18
So magne ic alloys should ha e high Cu ie empe a u e o enla ge he maximum se ice
empe a u e, la ge sa u a ion magne iza ion o maximize he magne ic lux, la ge ini ial
pe meabili y and minimal coe ci i y o educe he hys e esis losses. In Figu e 6 he M(H)
loops o as-spun ibbons a e p esen ed o all ou composi ions. The shape o he cu e
exhibi s a e y sha p inc ease o magne iza ion a low applied ields, hallma k o a high ini ial
pe meabili y, eaching nea ly he sa u a ion alue below applied ields o 𝜇𝜇0𝐻𝐻=0.2 T.
Fu he mo e, sa u a ion magne iza ion (Ms) alues can be es ima ed as he magne iza ion a
he highes applied ield (1.5 T) p o ided he slope o he M-H cu e is 𝑑𝑑𝑑𝑑
𝑑𝑑𝑑𝑑 ≈0. The
e olu ion o he no malized magne iza ion, 𝑑𝑑𝑠𝑠(𝑇𝑇)
𝑑𝑑𝑠𝑠(298 𝐾𝐾) wi h empe a u e o he as-spun ibbons
is plo ed in Fig. 7. A d op o ze o magne iza ion demons a es he e omagne ic o
pa amagne ic ansi ion o he amo phous s uc u e. The Cu ie empe a u e o he as-spun
ibbons o he di e en composi ions has been calcula ed using He ze me hod desc ibed in
he expe imen al sec ion. Figu e 8 compa es (da a also ep oduced in Table 5) he alues o
sa u a ion magne iza ion and Cu ie empe a u e in unc ion o Gd con en . Gd- ee alloys has
he la ges alues wi h a Cu ie empe a u e o 676 K and Ms=113 Am2/kg, which a e alues
consis en wi h hose ound by o he au ho s in alloys wi h close composi ion [47]. The
addi ion o Gd has a de imen al e ec on sa u a ion magne iza ion and Cu ie empe a u e.
Fig. 8 shows ha he shi o he Cu ie empe a u e o lowe alues is no linea , bu he slope
o he cu e ge s s eppe as Gd con en becomes la ge . A simila end is ound in he
sa u a ion magne iza ion beha iou . Bo h magni udes depend on he exchange coupling
be ween TM a oms (Fe and Co), whe e he magne ic momen s ca ied by 3d elec ons couple
e omagne ically. In con as , he Gd a oms possess 4 elec ons, which in e ac wi h
localized 3d elec ons o Fe and Co an i e omagne ically p oducing he educ ion o he
19
o e all magne ic momen . Buschow and co-wo ke s [48] calcula ed he no malized magne ic
momen in amo phous Gd-Fe and Gd-Co alloys using a model based on he p obabili y o Fe
(o Co) ha ing n Fe a oms as nea es neighbou s. They ound a good co ela ion wi h
expe imen al da a. The magne ic momen pe uni o a om has a quasi-linea change wi h Gd
concen a ion a in e media e concen a ion bu ends o smoo h down as he concen a ions
ends o pu e Fe (o Co). Mo eo e , he obse ed change o he mean hype ine ield in he
amo phous by Mössbaue spec oscopy (inse Fig 4(b)) co esponds pe ec ly o he magne ic
magni udes and he e o e con i m his in e p e a ion based on he idea ha magne ic
p ope ies a e de e mined by he exchange in e ac ions be ween Fe (o Co) a oms and hei
closes en i onmen s. The alue o coe ci i y o as-spun ibbons is below 10 A/m which
indica es ha a e excellen so magne ic alloys, e en wi h no u he annealing. Li and
cowo ke s epo ed an inc ease o coe ci i y wi h he addi ion o a RE like Tb and hey
a ibu ed i o he la ge aniso opy cons an [22]. I is wo h no ing, ha he Hc o Gd5
alloys could no be measu ed because o he limi a ions o he expe imen al de ice due o he
laky-shape o he ibbon.
Table 5. Cu ie empe a u e (TC), sa u a ion magne iza ion (Ms) and coe ci i y (Hc) o
[(Fe0.6Co0.4)0.75Si0.05B0.20]96-xNb4Gdx (x=0,1,2,5) alloys.
T
C
(K)
H
c
(A/m)
M
s
(Am2/kg)
Gd0
676±1
2.2±1.1
113±1
Gd1
666±1
10.7±0.5
108±1
Gd2
624±3
3.6±1.3
96±2
Gd5
555±3
-
68±1
20
Figu e 6. M-H cu es measu ed a T=305 K o [(Fe0.6Co0.4)0.75Si0.05B0.20]96-xNb4Gdx
(x=0,1,2,5) alloys.
21
Figu e 7. No malized magne iza ion in unc ion o empe a u e o
[(Fe0.6Co0.4)0.75Si0.05B0.20]96-xNb4Gdx (x=0,1,2,5) alloys.
Figu e 8. Cu ie empe a u e (Tc) and sa u a ion magne iza ion (Ms) plo ed agains Gd
concen a ion.
22
Conclusions
To sum up, he ole o Gd mic oalloying in [(Fe0.6Co0.4)0.75Si0.05B0.20]96-xNb4Gdx (x=0,1,2,5)
alloys has been in es iga ed. On he one hand, he la ge he mal s abili y o he amo phous
phase up o highe empe a u es and he imp o emen o he GFA p edic ing pa ame e s wi h
he addi ion o Gd poin o an enhancemen o glass o ming abili y wi h he addi ion o Gd.
On he o he hand, he expe imen al cas ing o he alloys shows a c i ical diame e below 1.5
mm in he Gd5 alloy. The p ima y c ys alliza ion o glassy ibbons has been in es iga ed
using x- ay di ac ion and T ansmission Mössbaue spec oscopy. Whe eas in alloys wi h
low amoun o Gd (x=0,1,2) he main c ys alliza ion phase is Fe23B6- ype bo ide, in he alloy
wi h la ge amoun o Gd (x=5), he p ima y c ys alliza ion p oceeds h ough he
p ecipi a ion o mul iple phases like Fe3B, FeB, bcc-Fe(Co), Fe2Nb, Fe2Gd and FeSi.
The e o e, we conclude ha he de e io a ion o he GFA in he la e alloy is ela ed o a
di e en de i i ica ion pa h in espec o Gd0, Gd1 and Gd2 alloys, especially o he
o ma ion o phases wi h smalle uni cell han Fe23B6- ype bo ide. Magne ic p ope ies a e
also in luenced by he addi ion o Gd. Bo h Cu ie empe a u e and sa u a ion magne iza ion
o he me allic glasses a e educed wi h Gd.
Acknowledgemen s
Pa o he expe imen al wo k epo ed in his pape was conduc ed a IFW-D esden by J.
To ens-Se a du ing a pos -doc o al s ay inancially suppo ed om Gene ali a de
Ca alunya h ough a “Bea iu de Pinós” g an (Nº 2009 BP-A 00138). P o . J. Ecke and D .
M. S oica a e acknowledged o ui ul discussions and assis ance. J. To ens-Se a and B.
Kus o also acknowledges inancial suppo om he Comuni a Au ònoma de les Illes
23
Balea s h ough he Se ei de Rece ca i Desen olupamen and he Conselle ia d'Educació i
Uni e si a s wi h unds om he Tou is S ay Tax Law ITS (PDR2020/39-2 - ITS2017-006).
P. B una acknowledges inancial suppo om G an PID2023-146623NB-I00 unded by
MICIU/AEI/10.13039/501100011033 and by ERDF/EU, Gene ali a de Ca alunya AGAUR
g an 2021-SGR-00343.
This wo k is pa o Ma ia de Maez u Uni s o Excellence P og amme
CEX2023-001300-M / unded by MCIN/AEI / 10.13039/501100011033.
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