ma e ials
A icle
Fundamen al Imp o emen o C eep Resis ance o
New-Gene a ion Nano-Oxide S eng hened Alloys
ia Ho Ro a y Swaging Consolida ion
Jiˇ íS oboda 1,*, Lenka Kunˇcická1,2, Na ália Lup áko á1, Adam Weise 1and Pe Dymáˇcek 1
1Ins i u e o Physics o Ma e ials, Czech Academy o Sciences, Žižko a 22, 616 62 B no, Czech Republic;
[email p o ec ed] (L.K.); [email p o ec ed] (N.L.); [email p o ec ed] (A.W.); [email p o ec ed] (P.D.)
2Facul y o Ma e ials Science and Technology, VŠB–Technical Uni e si y o Os a a, 17. Lis opadu 15,
708 33 Os a a, Czech Republic
*Co espondence: [email p o ec ed]
Recei ed: 22 Oc obe 2020; Accep ed: 16 No embe 2020; Published: 18 No embe 2020


Abs ac :
New-gene a ion oxide dispe sion-s eng hened (ODS) alloys wi h a high olume ac ion
o nano-oxides o 5% a e in ended o become he leading c eep- and oxida ion- esis an alloys o
applica ions a 1100–1300
◦
C. Ho consolida ion o mechanically alloyed powde s by in ensi e plas ic
de o ma ion ollowed by hea ea men o he alloys a e he key aspec s o achie ing op c eep
p ope ies, ypically ensu ed by a coa se-g ained mic os uc u e s eng hened wi h homogeneously
dispe sed, e y s able y ium nano-oxides. The o a y swaging me hod p o es o be a ou able o
ho consolida ion o he new-gene a ion ODS alloy p esen ed. Compa ed o specimens consolida ed
by ho olling, consolida ion by ho o a y swaging p ede e mines he o ma ion o coa se g ains wi h
a e y high aspec a io du ing subsequen seconda y ec ys alliza ion. Such a g ain mo phology
inc eases he c eep s eng h o he new-gene a ion ODS alloy conside ably.
Keywo ds:
oxide dispe sion s eng hened (ODS) alloy; mechanical alloying; powde ho consolida ion;
olling; o a y swaging
1. In oduc ion
The de elopmen o ad anced ma e ials wi h excellen high- empe a u e c eep and oxida ion
esis ance is one o he mos challenging goals o con empo a y ma e ial esea ch. Ni-based supe alloy
single c ys als [
1
] applicable up o 1100
◦
C, oxide dispe sion-s eng hened (ODS) e i ic alloys [
2
]
applicable up o 1300
◦
C, and ungs en hea y alloys (THAs) [
3
] applicable up o 1500
◦
C, a e he
op-le el me allic ma e ials wi h he bes c eep pe o mance.
Ni-based supe alloy single c ys als a e ypically s eng hened by abou 70% olume ac ion o
cuboidal γ´-p ecipi a es sepa a ed by hin channels o diso de ed γma ix [4,5]. Su icien con en o
Al in he supe alloys ensu es hei excellen oxida ion esis ance. Howe e , cu ing he
γ´
-phase by
disloca ion, and ins abili y o he
γ´
-p ecipi a es due o hei coa sening o a ing a empe a u es
abo e 900
◦
C, signi ican ly limi s long- e m applicabili y o Ni-based supe alloys in he empe a u e
ange o 900–1100
◦
C. The ODS alloys a e s eng hened by nano-dispe sion o e y s able Y-based
oxides, ypically o 5–20 nm in size and 0.5% olume ac ion [
6
,
7
]. The e i ic ma ix o he ODS alloys
also allows su icien alloying by Al (up o 10 w .%) ensu ing hei excellen oxida ion esis ance [
8
].
Bo h he e y good c eep and excellen oxida ion esis ance a e al eady co e ed by he exis ing ODS
alloys o empe a u es up o 1300
◦
C. The THAs p o i om e y high mel ing poin combined wi h
solid solu ion and de o ma ion s eng hening [
9
,
10
]. The THAs a e, howe e , disquali ied by hei
poo oxida ion esis ance and high speci ic mass. Thus, he mos p omising candida e o he op c eep-
Ma e ials 2020,13, 5217; doi:10.3390/ma13225217 www.mdpi.com/jou nal/ma e ials
Ma e ials 2020,13, 5217 2 o 11
and oxida ion- esis an alloys o long- e m applica ions in he empe a u e ange o 1100–1300
◦
C
s ems om he amily o he ODS alloys.
ODS alloys a e ypically p oduced in wo s eps. Homogeneous powde consis ing o he
ma ix and nano-sized Y
2
O
3
is p oduced by (i) mechanical alloying (MA) and (ii) consolida ed
ia (a) ho ex usion (HE), (b) ho isos a ic p essing (HIP), (c) spa k plasma sin e ing, o hei
combina ion[
11
–
17
]. Ve y ecen esea ch by he au ho s de o ed o he de elopmen o new-gene a ion
ODS alloys wi h a high olume ac ion o oxides o abou 5% (being by one o de o magni ude
highe han in classical ODS alloys) consolida ed ia ho olling [
6
,
18
] indica es ha he consolida ion
condi ions a e impo an ac o s in luencing he inal c eep p ope ies o he alloys. Ne e heless,
addi ional de o ma ion ( he momechanical) p ocessing o he ODS alloys is o en applied o ensu e
elimina ion o po osi y and enhance hei pe o mance. The p ocessing can be pe o med ia nume ous
con en ional, as well as uncon en ional, o ming me hods. Among he con en ional ones a e,
o example, olling and o ging. Recen ly, Auge e al. [
19
] used ho -c oss olling o imp o e
esis ance o 14YWT ODS alloy agains adia ion, and Zhang e al. [
20
] applied ho olling o inc ease
he s eng h o Fe–9C -0.06C-1.5W-0.5Ti-0.18Si-0.35Y
2
O
3
ODS alloy (w .% a e used in all no a ions).
Kuma e al. [
21
] s udied mechanical p ope ies o Fe-18C -2W-0.2Ti-xY
2
O
3
alloy consolida ed om
mechanically alloyed powde by o ging. Zhou e al. [
22
] applied combina ions o o ging, ho olling,
cold olling, and annealing o ODS310 alloy wi h Mo addi ion. Howe e , inhomogeneous bimodal
g ain size dis ibu ion due o incomple e seconda y ec ys alliza ion and b i le c acking along he g ain
bounda ies a e s ill issues o he ODS alloys [
23
]. Al hough coa se g ain mic os uc u e achie ed by ull
seconda y ec ys alliza ion seems o be he key ac o o acqui ing excellen c eep s eng h, se e al ODS
alloys in es iga ed in he a ailable li e a u e do no mee his equi emen . Ou expe imen s indica e
ha he ul a ine g ained mic os uc u e o incomple e seconda y ec ys alliza ion in he ODS alloy
cause he c eep s eng h o each only a ac ion o he c eep s eng h o he comple ely ec ys allized
ones. Mo eo e , in se e al pape s, he mechanical p ope ies o e y expensi e ODS alloys a e s udied
a loading condi ions, o which much be e and cheape subs i u es exis . I is highly desi able o
limi he s udies o ODS alloys o condi ions, a which hei p ope ies a e eally excep ional.
The o e all pe o mance o he ODS alloys can be imp o ed in wo ways, he i s o which is
modi ica ion o hei chemical composi ion. The new-gene a ion ODS alloys a e p epa ed om powde s
mechanically alloyed up o a deg ee o homogenei y a which he o e all amoun o oxygen o igina ing
om he inpu y ia powde and oxidized su aces o he inpu me allic powde s is comple ely
dissol ed and apped a de ec s, such as disloca ions and acancies. A e canning, he powde is
ho olled unde op imized condi ions ensu ing he elimina ion o po osi y, as well as p o oking
dynamic ec ys alliza ion esul ing in ul a- ine g ained (UFG) mic os uc u e. Nano-oxides o he
ypical size o 5 nm, p ecipi a ed du ing he ho consolida ion, s abilize he UFG mic os uc u e up o
e y high empe a u es o 1000–1100
◦
C. I he ene gy s o ed du ing he ho olling eaches he c i ical
alue, comple e seconda y ec ys alliza ion occu s du ing subsequen annealing a he empe a u es o
1200
◦
C o se e al hou s [
6
,
18
]. As he esul , he inal mic os uc u e consis s o coa se g ains o he
ypical size in he o de o 100
µ
m s eng hened by homogeneous dispe sion o y ium nano-oxides
o he ypical size o 20 nm [
24
]. Tensile es s pe o med a empe a u es exceeding 1000
◦
C lead o
a a he b i le in e g anula ac u e, which indica es ha high-angle g ain bounda ies a e he weakes
link in he new-gene a ion ODS alloys due o hei limi ed cohesion s eng h. Howe e , o c eep
expe imen s a he applied s ess o 40–60% o he s eng h measu ed by he ensile es , he cohesion
o high-angle g ain bounda ies is su icien and he s a iona y c eep a e d ops o he alues o he
o de o 10
−9
s
−1
, as he dispe sion o nano-oxides e y e ec i ely supp esses he disloca ion c eep [
25
]
and he ime o ac u e eaches hund eds o housands o hou s. Mo eo e , as he p ima y c eep
s ain is a he small, ypically 0.1–0.2%, he new-gene a ion ODS alloys a e ad an ageous o design
componen s equi ing long- e m igidi y a e y high empe a u es.
The second way in which he pe o mance o he ODS alloys can be enhanced is he applica ion
o op imized de o ma ion p ocessing ( he momechanical ea men ), which can ad an ageously
Ma e ials 2020,13, 5217 3 o 11
be pe o med by uncon en ional o ming echniques and me hods o se e e plas ic de o ma ion
(SPD). SPD me hods such as equal channel angula p essing (ECAP) [
26
,
27
] and ela ed me hods
(non-ECAP [
28
], wis channel (mul i-) angula p essing [
29
,
30
], e c.), o high p essu e o sion (HPT) [
31
]
a e a ou able o p ocessing o small olumes o ma e ials, while me hods such as accumula i e
oll bonding (ARB) [
32
,
33
] and o a y swaging (RS) [
34
] a e ad an ageous o la ge bulk p oduc s.
Ro a y swaging (RS) has been used o pe o m he momechanical p ocessing o a ious alloys,
om b i le Mg-based compounds [
35
,
36
], h ough bio-applicable NiTi shape memo y alloys [
37
,
38
],
Ti-based ma e ials wi h enhanced pe o mance [
39
], and me allic composi es [
40
,
41
], o FeCo magne ic
compounds [
42
], and mode n s eels [
43
]. RS was also applied o he Eu o e ’97 ype o ODS a e
consolida ion by HIP o HE [
44
]. RS seems o be e y p omising pa icula ly o consolida ion o
canned ODS powde s due o i s inc emen al cha ac e , p e ailing comp essi e s ess s a e, and high
imposed shea s ains [
45
–
47
]. Compa ed o HE, RS is a s anda d indus ial echnology allowing
ela i ely easy and cheap p oduc ion o solid, hollow, o p o iled ba s wi hin a wide ange o diame e s.
The p esen s udy in oduces he Fe-10Al-3Y
2
O
3
-1Ti new-gene a ion ODS alloy consolida ed om
a mechanically alloyed powde by wo me hods o in ensi e plas ic de o ma ion: (i) ho olling, and (ii)
ho RS. To he bes o he au ho s’ knowledge, his is he e y i s expe imen in which ho RS has
been u ilized o ODS alloy consolida ion. To demons a e he a ou able e ec s o RS, mic os uc u es
and c eep p ope ies o olled and swaged samples a e compa ed and he esul s o expe imen s a e
discussed in de ail.
2. Ma e ials and Me hods
Chemically homogeneous Fe-10Al-3Y
2
O
3
-1Ti powde was p epa ed om Fe, Al, Y
2
O
3
, and Ti
powde s o 99.9% pu i y by MA using a sel -made ball mill. A acuum- igh milling con aine wi h
he olume o 22 dm
3
and diame e o 400 mm made om low alloyed s eel was illed wi h 100
Fe-1C -1C bea ing balls o 40 mm diame e (al oge he 25 kg). The o al amoun o 1 kg o he powde
was mechanically alloyed by o a ion o he milling con aine along he ho izon al axis (70 pm).
A e a su icien ly long MA ( wo weeks) in acuum, he powde p ope ies became sa u a ed and
he powde pa icles consis ed o a homogeneous solid solu ion wi h a huge densi y o de ec s,
like disloca ions and acancies (see [
6
] o mo e de ails). The a he wide size dis ibu ion (be ween 2
o 200 µm) o he cold compac ed powde can be de e mined om Figu e 1. I is e y complica ed o
de e mine he mean pa icle size due o e y wide size dis ibu ion. Mo eo e , he powde in ol es
a huge densi y o de ec s and he g ains and hei g ain bounda ies a e no well de ined. The measu ed
con en o C (0.05%) in he MA powde indica es ha abou 5% o he milling balls is in oduced
in o he MA powde by he ab asion o milling balls and hus he MA powde con ains also 0.05% o
C. The in luence o milling media on he mic os uc u e and mechanical p ope ies o mechanically
milled and sin e ed aluminium was analyzed e.g. in [48].
Figu e 1.
Me allog aphic sec ion o he mechanically alloyed powde o he new-gene a ion ODS alloy.
Ma e ials 2020,13, 5217 4 o 11
The MA powde was ho consolida ed by using wo echniques: (i) olling and (ii) RS. The olling
cylinde s o diame e 75 mm in he mill o a ed a he speed o 65 pm. The o a y swaging machine by
he HMP company allowed s epwise educ ion o axisymme ic ba s. Fou swaging dies pe o med
high- equency adial mo emen s wi h sho s okes and applied comp essi e o ce o he inse ed
wo kpiece. The o ming p ocess ook place in many small p ocessing s eps and, he e o e, RS can be
desc ibed as an inc emen al o ming p ocess. In eed swaging wi h lee ing clamping o he swaged
sample was used. The en i e swaging was pe o med a he empe a u e o 950
◦
C wi h no lub ica ion.
The specimens we e hea ed and kep 5 min a he equi ed empe a u e in he a mosphe ic u nace
be o e each consolida ion s ep.
The con aine s o ho olling and ho RS made om s ainless s eel ubes we e illed wi h he
mechanically alloyed powde , e acua ed, and sealed by welding. The olling con aine was ho olled
in h ee s eps om he ini ial diame e o 20 mm o he inal hickness o he shee o 3.2 mm a 960
◦
C.
The swaging con aine was ho o a y swaged om he ini ial diame e o 50 mm o he inal diame e
o 15 mm a he same empe a u e, o p o ide simila ho consolida ion condi ions. The schema ic
depic ion o he olling and swaging p ocesses o he new-gene a ion ODS alloy, including geome ies
o he canned semi-p oduc s and de ini ion o he u he desc ibed di ec ions, is shown in Figu e 2.
A e s ipping om he con aine s, he consolida ed new-gene a ion ODS alloys we e seconda ily
ec ys allized by annealing in a acuum u nace a 1200 ◦C o 4 h.
Figu e 2.
Rolling and swaging geome ies used o consolida ion o new-gene a ion oxide
dispe sion-s eng hened (ODS) alloys.
The s udy deals wi h wo se s o specimens o he seconda y ec ys allized new-gene a ion ODS
alloy. Fla specimens wi h he gauge leng h o 25 mm and c oss sec ion o 2.5 mm
×
3.5 mm cu
by p ecise wa e je and g inded om he olled shee s a e deno ed as Specimens I, while ci cula
specimens wi h he gauge leng h o 25 mm and diame e o 6 mm p oduced om he swaged ods a e
deno ed as Specimens II. The ensile and c eep es s we e pe o med using Zwick/Roell—Messphysik
KAPPA LA (Fü s en eld, Aus ia) sp ing 20 kN c eep es sys em equipped by MAYTEC u nace
(Singen, Ge many) wi h he wo king empe a u es up o 1400
◦
C. One specimen o a ensile es a
cons an a e 10
−6
s
−1
and ou , espec i ely i e, specimens we e used o he c eep es s o Specimens
I and II (i.e., one specimen o each applied s ess). The mic os uc u es we e obse ed using a scanning
elec on mic oscope (SEM) Tescan Ly a 3 XMU FEG/SEMxFIB (Tescan, B no, Czech Republic) equipped
wi h X-Max80 EDS (ene gy-dispe si e X- ay) de ec o o X- ay mic oanalysis and EBSD (elec on
backsca e di ac ion) de ec o wi h Az ec con ol sys em (Ox o d Ins umen s, Abingdon, UK).
3. Mechanical Tes ing
The ensile es s pe o med a he empe a u e o 1100
◦
C and s ain a e o 10
−6
s
−1
showed he
s eng h o 75 MPa and duc ili y o 1.1% o Specimens I, and s eng h o 115 MPa and duc ili y o 1.2%
o Specimens II. The a he small duc ili y and he pu ely in e g anula ac u e indica ed ha he
g ain bounda y cohesion s eng h was he weakes link in he specimens. This weakes link, howe e ,
did no necessa ily play an impo an ole in he c eep expe imen s a he applied s ess signi ican ly
below he measu ed ensile s eng h.
Ma e ials 2020,13, 5217 5 o 11
The esul s o c eep es s pe o med a 1100
◦
C a e summa ized in Figu e 3. To ge an idea
abou he c eep p ope ies o he new-gene a ion ODS alloy, he esul s a e compa ed wi h he da a
shee o he op comme cial ODS alloy, MA 956 [
49
] (only imes o up u e a e a ailable). Figu e 3a
ob iously shows ha he s ess exponen o ime o up u e is much highe o Specimens II compa ed
o Specimens I. This can be a ibu ed o he signi ican ly inc eased c eep duc ili y o Specimens II a
low s esses. The s ess exponen s o minimum c eep a e shown in Figu e 3b a e simila o bo h
Specimens I and II. I is e iden om he c eep es s (see Figu e 3a) ha he s eng h o Specimens II is
signi ican ly (by a ac o o abou 1.5 o 2) highe han ha o Specimens I and he minimum c eep a e
is lowe by mo e han wo o de s o magni ude (see Figu e 3b). To explain hese ac s, SEM analysis
was u he pe o med.
Figu e 3.
Compa ison o (
a
) ime o up u e; (
b
) minimum c eep a e o Specimens I and II. In e up ed
c eep es o Specimens II a 60 MPa is used o de e mine he minimum c eep a e.
4. Mic os uc u e Cha ac e iza ion
The mic os uc u es acqui ed by SEM (back-sca e ed elec on analysis) om cen al pa s o he
samples a e ho olling and ho RS a e compa ed in Figu e 4a,b, espec i ely. The g ain mic os uc u e
o he olled specimen (Figu e 4a) is e y ine (100 nm); he g ains a e mo e o less equiaxed (aspec a io
nea o 1) and exhibi a a he na ow size dis ibu ion. By con as , he g ain mic os uc u e a e RS
(Figu e 3b) is signi ican ly coa se ( he wid h o g ains 200 nm) and conside ably elonga ed (aspec a io
2.2) in he di ec ion o he swaging axis (ho izon al di ec ion).
Figu e 4.
Compa ison o mic os uc u es p epa ed by (
a
) ho olling in RollDxND plane; (
b
) ho o a y
swaging (RS) in SDxRadD plane.

Ma e ials 2020,13, 5217 6 o 11
The elec on backsca e di ac ion (EBSD) analyses o g ain mic os uc u es o Specimens I and
II a e seconda y ec ys alliza ion, which led o a d as ic inc ease in he g ain size by nea ly ou
o de s o magni ude, a e compa ed in Figu e 5. The shapes o he g ains in Specimens I sligh ly
esemble pancakes in he olling plane (ho izon al di ec ion in Figu e 5a), he g ains in Specimens
II exhibi shapes wi h a high aspec a io along he swaging axis (ho izon al di ec ion in Figu e 5b).
No signi ican ex u e o ma ion is de ec ed om he in e se pole igu es (see Figu e 5c,d).
Figu e 5.
Compa ison o g ain mic os uc u es a e seconda y ec ys alliza ion (
a
) Specimens I in
RollDxND plane; (
b
) Specimens II in SDxRadD plane, scanning elec on mic oscopy (SEM)–elec on
backsca e di ac ion (EBSD) in e se pole igu es o (
c
) Specimens I; (
d
) Specimens II. Indi idual
di ec ions a e de ined in Figu e 2.
The mic os uc u es ea u ing dispe sions o nano-oxides inside he seconda y ec ys allized
g ains o Specimens I and II a e compa ed in Figu e 6, which show ha he oxide dispe sion in
Specimens I is signi ican ly ine and mo e homogeneous han in Specimens II. The eason o he
di e ence can be ound in he compa ison o g ain mic os uc u es a e ho consolida ion p esen ed
in Figu e 4. The g ains a e ho olling a e e y ine (o he o de o 100 nm) and he size o he
oxides ( ypically 5 nm, see Figu e 1b in e e ence [
50
]) is below he esolu ion o SEM ( ypically
obse ed by ansmission elec on mic oscopy). The oxides a he g ain bounda ies coa sen as e
han hose wi hin he g ain in e io s du ing annealing and hus he mo phology o he ho - olled
mic os uc u e (see Figu e 4a) is imp in ed in he oxide dispe sion a e seconda y ec ys alliza ion.
Only he nano-oxides o iginally si ua ed a he g ain bounda ies o he UFG mic os uc u e emain
as hey consume he nano-oxides om in e io s o ul a ine g ains du ing annealing. The g ain
mic os uc u e a e ho RS is much coa se (500–1000 nm) han ha a e ho olling and he g ains
a e conside ably elonga ed in he di ec ion o swaging axis, see Figu e 4b. Mo eo e , he swaged
s uc u e al eady con ains some po ion o ela i ely coa se nano-oxides (20–50 nm). By hese easons,
he nano-oxide dispe sion in Specimens II, e lec ing he ho -swaged g ain mic os uc u e, is coa se
and less homogeneous and ea u es a wide size dis ibu ion. As he nano-oxides a e again si ua ed
p edominan ly in loca ions o he o iginal g ain bounda ies a e RS, he nano-oxides o m chains
pa allel o he swaging axis a he me allog aphic sec ion in Figu e 6b.
Ma e ials 2020,13, 5217 7 o 11
Figu e 6.
Compa ison o mic os uc u es o nano-oxide dispe sion wi hin g ains o (
a
) Specimens I
(b) Specimens II (SEM—backsca e ed elec ons).
5. Discussion
The o ma ion o g ains wi h high aspec a io in Specimens II by seconda y ec ys alliza ion
(Figu e 5b) can be explained as ollows. Due o he Zene pinning, he g ain bounda y o he seconda y
ec ys allizing g ain mig a es easily ac oss he zones o low-densi y o nano-oxides and emains
ancho ed in he zones wi h a e y high densi y o nano-oxides. As he nano-oxides a e concen a ed
p edominan ly a he loca ions o he o iginal g ain bounda ies a e RS, i.e., p edominan ly a su aces
pa allel o he swaging axis, he e ec i e mobili y is signi ican ly lowe o he g ain bounda ies pa allel
o he swaging axis han o hose no mal o he swaging axis. Du ing he subsequen seconda y
ec ys alliza ion, he g ow h a e o he g ains aligned wi h he swaging axis is highe han he g ow h
a e o he g ains aligned wi h he no mal o he swaging axis, which explains he o ma ion o g ains
wi h high aspec a io pa allel o he swaging axis a e seconda y ec ys alliza ion (see Figu e 5b).
When uniaxial s ess is applied a e y high empe a u es, edis ibu ion o s ess wi hin he
specimen occu s apidly and a ce ain pa o he applied s ess is equilib a ed by shea s esses
a he g ain bounda ies pa allel o he di ec ion o he applied s ess. The highe ac ion o g ain
bounda ies pa allel o he loading axis exis s in he specimen, and mo e loading is ans e ed by his
edis ibu ion e ec . As he ac ion o g ain bounda ies pa allel o he loading axis is signi ican ly
highe in Specimens II han in Specimens I, and he cohesi e s eng h o he g ain bounda ies no mal
o he applied s ess is he gi en limi ing ac o , he s eng h o Specimens II is conside ably highe
han o ha o Specimens I.
The g ain geome y wi h high aspec a io and nano-oxide dis ibu ion pa e n leads o aniso opy
in he mechanical p ope ies and de e mines high ensile s eng h along he swaging axis. This may be
ad an ageous o speci ic uniaxially loaded componen s, such as pull ods and g ips in es ing machines
wo king a e y high empe a u es. Mo eo e , excellen oxida ion esis ance o he Fe-10Al-3Y
2
O
3
-1Ti
is gua an eed by he high con en o Al o ming a p o ec i e compac alumina su ace ilm by eac ion
wi h he ai . The p o ec i e ilm may also p ohibi eac ion o pull ods and g ips wi h es ed specimens.
Special ca e mus be aken o a oid signi ican inhomogenei ies in he g ain size, as his may cause
seconda y c acking o delamina ion, as desc ibed in [
51
,
52
]. Thus, comple e seconda y ec ys alliza ion
is equi ed op oceedin hesamples. The espec i emodel o he ea men o dynamic ec ys alliza ion
du ing ho consolida ion ollowed by seconda y ec ys alliza ion is p esen ed in [
50
]. The model
clea ly shows ha only selec ed ho consolida ion condi ions om he p ocessing window may lead o
comple e seconda y ec ys alliza ion du ing subsequen annealing, which is he case o in his s udy.
Conce ning he mechanical p ope ies a 1100
◦
C, he in luence o he consolida ion me hod is
subs an ial. Bo h he ensile es s eng h and c eep s eng h a e by a ac o o abou 1.5 o 2 highe o
Specimens II han o Specimens I. This is despi e he ac ha he nano-oxide dispe sion in Specimens
Ma e ials 2020,13, 5217 8 o 11
I is mo e egula han ha in Specimens II, see Figu e 6. Summa izing based on he con incing esul s,
he g ains in bo h Specimens I and II a e su icien ly s eng hened by he dispe sion o nano-oxides and
he mechanical p ope ies a 1100
◦
C a e, o he gi en cohesion o he g ain bounda ies, de e mined
p edominan ly by he g ain geome y.
Today, ODS alloys a e no p oduced on he comme cial basis any mo e, which is mos p obably
due o hei a he complica ed p ocessing esul ing in a e y high p ice and, consequen ly, low ma ke
demand. The p ocessing o new-gene a ion ODS alloys is much less complica ed when u ilizing
s anda d indus ial p ocedu es such as olling o RS o ho consolida ion. The use o he sel -made
a i o is also e y simple and cheap and i allows easy up-scaling. I he chemical composi ion
and ho -consolida ion condi ions a e op imized o ensu e he comple e seconda y ec ys alliza ion as
a s anda d, he powe o p ize a io o he new-gene a ion ODS alloys will be signi ican ly highe han
ha o he ecen ODS alloys and comme cial in e es in ODS alloys enewed.
6. Conclusions
The conclusions can be summa ized as ollows:
•
Two ba ches o he Fe-10Al-3Y
2
O
3
-1Ti new-gene a ion ODS alloys a e p epa ed by ho
consolida ion o mechanically alloyed powde using (i) olling and (ii) o a y swaging.
•
Seconda y ec ys alliza ion o he ho o a y swaging consolida ed specimens ea u ing
ul a- ine-g ained mic os uc u e leads o a he coa se g ains signi ican ly elonga ed in he
di ec ion o swaging axis.
•
Al hough he mic os uc u e o nano-oxides in he seconda y ec ys allized g ains o he ODS
alloy consolida ed by ho olling is signi ican ly mo e egula and ine han ha o he ODS alloy
consolida ed by ho o a y swaging, he s eng h o he la e a 1100
◦
C is by a ac o o 1.5 o 2
highe han ha o he i s one.
•
The c eep s eng h o he p esen new-gene a ion o ODS alloy a 1100
◦
C is p edominan ly
de e mined by he mo phology o g ain bounda ies being he weakes link due o hei limi ed
cohesi e s eng h.
•
The c eep s eng h a 1100
◦
C o he new-gene a ion ODS alloys consolida ed by ho o a y
swaging exceeds ha o op comme cial ODS alloy by mo e han 30%.
•
The ho consolida ion o he ODS powde ia o a y swaging compa ed o olling is p o en
ad an ageous o p oduc ion o he new-gene a ion high-s eng h ODS alloys o applica ion a
empe a u es 1100–1300 ◦C.
Au ho Con ibu ions:
J.S., concep ualiza ion, me hodology, mechanical alloying, olling and w i ing; L.K.,
o a y swaging, e iewing and edi ing; N.L., SEM elec on mic oscopy—EBSD and edi ing; A.W., SEM elec on
mic oscopy; P.D., mechanical es ing, e iewing and edi ing. All au ho s ha e ead and ag eed o he published
e sion o he manusc ip .
Funding: J.S. and P.D. acknowledge he unding by he Czech Science Founda ion g an numbe 17-01641S. L.K.
acknowledges he unding by Minis y o Indus y and T ade g an numbe FV40286 in TRIO p og amme.
Con lic s o In e es : The au ho s decla e no con lic o in e es .
Re e ences
1.
S oboda, J.; Luk
á
š, P. Model o c eep in<001>-o ien ed supe alloy single c ys als. Ac a Ma e .
1998
,46,
3421–3431. [C ossRe ]
2.
Oksiu a, Z. High- empe a u e oxida ion esis ance o ul a ine-g ained 14% C ODS e i ic s eel. J. Ma e . Sci.
2013,48, 4801–4805. [C ossRe ]
3.
Kunˇcick
á
, L.; Kocich, R.; He oches, C.; Mach
á
ˇcko
á
, A. S udy o s uc u e and esidual s esses in cold
o a y swaged ungs en hea y alloy. Ma e . Sci. Eng. A 2017,704, 25–31.
4.
S oboda, J.; Luk
á
š, P. C eep de o ma ion modelling o supe alloy single c ys als. Ac a Ma e .
2000
,48,
2519–2528. [C ossRe ]
Ma e ials 2020,13, 5217 9 o 11
5.
Pollock, T.M.; A gon, A.S. Di ec ional coa sening in nickel-base single c ys als wi h high olume ac ions o
cohe en p ecipi a es. Ac a Me all. Ma e . 1994,42, 1859–1874. [C ossRe ]
6.
S oboda, J.; Ho n
í
k, V.; S a il, L.; Had aba, H.; Mašek, B.; Khalaj, O.; Ji ko
á
, H. Mic os uc u e E olu ion in
ODS Alloys wi h a High-Volume F ac ion o Nano Oxides. Me als 2018,8, 1079. [C ossRe ]
7.
Ka ak, S.K.; Majumda , J.D.; Wi czak, Z.; Lojkowski, W.; Ciupi´nski, Ł.; Ku zydłowski, K.J.; Manna, I.
E alua ion o Mic os uc u e and Mechanical P ope ies o Nano-Y
2
O
3
-Dispe sed Fe i ic Alloy Syn hesized
by Mechanical Alloying and Consolida ed by High-P essu e Sin e ing. Me all Ma e . T ans. A
2013
,44,
2884–2894. [C ossRe ]
8.
S a il, L.; Ho n
í
k, V.; Dym
á
ˇcek, P.; Roupco
á
, P.; S oboda, J. The in luence o aluminium con en on oxida ion
esis ance o new-gene a ion ODS alloy a 1200 ◦C. Me als 2020,10. unde e iew p ocedu e. [C ossRe ]
9.
Kunˇcick
á
, L.; Mach
á
ˇcko
á
, A.; La e y, N.P.; Kocich,R.; Cullen, J.C.T.; Hla
á
ˇc, L.M. E ec o he momechanical
p ocessing ia o a y swaging on p ope ies and esidual s ess wi hin ungs en hea y alloy. In . J. Re ac .
Me . Ha d Ma e . 2020,87, 105120. [C ossRe ]
10.
Kocich, R.; Kunˇcick
á
, L.; Dohnal
í
k, D.; Mach
á
ˇcko
á
, A.; Šo e , M. Cold o a y swaging o a ungs en hea y
alloy: Nume ical and expe imen al in es iga ions. In . J. Re ac . Me . Ha d Ma e .
2016
,61, 264–272. [C ossRe ]
11.
Byun, T.S.; Yoon, J.H.; Wee, S.H.; Hoelze , D.T.; Maloy, S.A. F ac u e beha io o 9C nanos uc u ed e i ic
alloy wi h imp o ed ac u e oughness. Nucl. Ma e . 2014,449, 39–48. [C ossRe ]
12.
Kim, J.H.; Byun, T.S.; Hoelze , D.T.; Kim, S.W.; Lee, B.H. Tempe a u e dependence o s eng hening
mechanisms in he nanos uc u ed e i ic alloy 14YWT: Pa I-Mechanical and mic os uc u al obse a ions.
Ma e . Sci. Eng. A. 2013,559, 101–110. [C ossRe ]
13.
Fu, J.; B ouwe , J.C.; Richa dson, I.M.; He mans, M.J.M. E ec o mechanical alloying and spa k plasma
sin e ing on he mic os uc u e and mechanical p ope ies o ODS Eu o e . Ma e . Des.
2019
,177, 107849.
[C ossRe ]
14.
Massey, C.P.; D yepond , S.N.; Edmondson, P.D.; Te ani, K.A.; Zinkle, S.J. In luence o mechanical alloying
and ex usion condi ions on he mic os uc u e and ensile p ope ies o Low-C ODS FeC Al alloys.
J. Nucl. Ma e . 2018,512, 227–238. [C ossRe ]
15.
Li, J.; Wu, S.; Ma, P.; Yang, Y.; Wu, E.; Xiong, L.; Liu, S. Mic os uc u e e olu ion and mechanical p ope ies o
ODS FeC Al alloys ab ica ed by an in e nal oxida ion p ocess. Ma e . Sci. Eng. A
2019
,757, 42–51. [C ossRe ]
16.
Li, Z.; Lu, Z.; Xie, R.; Lu, C.; Shi, Y.; Liu, C. E ec s o Y
2
O
3
, La
2
O
3
and CeO
2
addi ions on mic os uc u e and
mechanical p ope ies o 14C -ODS e i e alloys p oduced by spa k plasma sin e ing. Fusion Eng. Des.
2017
,
121, 159–166. [C ossRe ]
17.
Mon es, J.M.; Cue as, F.G.; Cin as, J.; U ban, P. A One-Dimensional Model o he Elec ical Resis ance
Sin e ing P ocess. Me all. Ma e . T ans. A 2015,46, 963–980. [C ossRe ]
18.
B
á
ko
á
, D.; Šm
í
d, M.; Mašek, B.; S oboda, J.; Šiška, F. Kine ic s udy o s a ic ec ys alliza ion in an Fe–Al–O
ul a- ine-g ained nanocomposi e. Phil. Mag. Le . 2017,97, 379–385. [C ossRe ]
19.
Auge , M.A.; Hoelze , D.T.; Field, K.G.; Moody, M.P. Nanoscale analysis o ion i adia ed ODS 14YWT e i ic
alloy. J. Nucl. Ma e . 2020,528, 151852. [C ossRe ]
20.
Zhang, G.; Zhou, Z.; Mo, K.; Miao, Y.; Xu, S.; Jia, H.; Liu, X.; S ubbins, J.F. The e ec o he mal-aging on he
mic os uc u e and mechanical p ope ies o 9C e i ic/ma ensi ic ODS alloy. J. Nucl. Ma e .
2019
,522,
212–219. [C ossRe ]
21.
Kuma , D.; P akash, U.; Dabhade, V.V.; Laha, K.; Sak hi el, Z. De elopmen o Oxide Dispe sion S eng hened
(ODS) Fe i ic S eel Th ough Powde Fo ging. J. Ma e . Eng. Pe o m. 2017,26, 1817–1824. [C ossRe ]
22.
Zhou, Z.; Sun, S.; Zou, L.; Schneide , Y.; Schmaude , S.; Wang, M. Enhanced s eng h and high empe a u e
esis ance o 25C 20Ni ODS aus eni ic alloy h ough he mo-mechanical ea men and addi ion o Mo.
Fusion Eng. Des. 2019,138, 175–182. [C ossRe ]
23.
Pal, S.; Alam, M.E.; Maloy, S.A.; Hoelze , D.T.; Ode e, R.G. Tex u e e olu ion and mic oc acking mechanisms
in as-ex uded and c oss- olled condi ions o a 14YWT nanos uc u ed e i ic alloy. Ac a Ma e .
2018
,152,
338–357. [C ossRe ]
24.
S oboda, J.; Lup
á
ko
á
, N.; Ja
ý
, M.; Dym
á
ˇcek, P. In luence o ho consolida ion condi ions and C -alloying
on mic os uc u e and c eep in new-gene a ion ODS alloy a 1100 ◦C. Ma e ials 2020, in p ess.
25.
Rösle , J.; A z , E. A new model-based c eep equa ion o dispe sion s eng hened ma e ials. Ac a Me all.
1990,38, 671–683. [C ossRe ]