7/27/2019 PointDefectClustersInCuTiAndTiAlver4cleanFramed
1/1
TypicalpointdefectclustersproducedinCu,TypicalpointdefectclustersproducedinCu,ZrandTiZrandTiAlbasedstructuralAlbasedstructuralintermetallicsexposedtofastparticleirradiationintermetallicsexposedtofastparticleirradiation
RomanVoskoboinikovRomanVoskoboinikov
TheInstituteofMaterialsEngineering,AustralianNuclearScienceandTechnologyOrganisationTheInstituteofMaterialsEngineering,AustralianNuclearScienceandTechnologyOrganisation
Movaon/Objecves
iAlbasedintermetallicalloysareconsideredascandidaterefractory
materialsforanumberofengineering
pplicaonsincludingnuclearpowersystems.Thisisduetotheirhighstrengthtoweightraoandexcellent
ightemperaturemechanicalproperes.Theupperboundoftheoperangtemperature
ofTiAlstructural
ntermetallicsisdeterminedbyitssevereembrilementbecauseofoxidaon.Apromisingapproachtoim
rovetheoxidaonresistanceofTialloysandTiAlintermetalliccompoundsistheuseofsurfaceengineer
ng.Surfacemodificaonbyionbeamtreatmentisawellestablishedmethodthatishoweveraccompaniedytheformaonofradiaondefects.Thenegaveimpactofionbombardmentisusuallymigatedbypost
irradiaonannealing. Inordertoopmise
ionbeamtreatmentandpostirradiaonannealingforthebest
performanceandtoqualifyTiAlbasedintermetallicsforuseinradiaonenvironmentdeepinsightintosta
bilityandproperesoftheproducedradiaondefectsisessenal.
Afewcomprehensiveprogrammes ofmodellingofradiaoneffects
inelementalmetalshavealreadybeen
conducted.Inordertoulisetheobtainedresultsanddevelopedmodellingtechniquesfortheinvesgaon
ofthemicrostructuralchanges
inTiAlbasedintermetalliccompoundsexposedtoirradiaon,thecompari
sonbetweentypicalclusters formed indisplacementcascades
inCu,Zr,L10TiAlandD019Ti3Alhasbeen
carriedout.
Summary
heresults
reported
here
are
based
onthe
outcome
ofalarge
set
ofsimula
ons
ofdisplacement
cascades
in
u,Zr,TiAlandTi3Al.Theradiaondefectnumberandconfiguraonvarystrongly
fromcascade tocas
ade,andsowehaveaemptedtogenerateandanalyseasufficientnumberofcascadesforeachcondion
fEpkaandTtodeterminedataanddetecttrendswithstascalsignificance.
Formaonofpointdefect
usters
underirradiaonisthemainconcernofthisresearch.Wehavecategorisedthedefectclusters
that
ypicallyariseincollisioncascadesinCuand
Zrandulisedthisdatainourstudyofradiaondefectsin
10TiAlandD019Ti3Al.Theclusteredselfintersalatoms(SIAs)tendtoformdislocaonloopsinallthema
erials.MobileSIAdislocaonloopswith1/2110 and1/21120
Burgersvectors inCu/TiAlandZr/Ti3Al,
especvely,arethemainSIAclusterconfiguraonsthatariseatalltemperatures
andprimaryknockonat
menergies.Apartfrom 1/2110SIAdislocaonloops,
faultedsessileSIAFrankloopswith1/3111Burg
rsvectorareformed incollisioncascades inCu.NoFrank
loopswereobserved inTiAltheresmallAlrich
disorderedSIAclusters areformedinstead.
TypicalSIAclusterconfiguraons inZrandTi3Alarenearly idencal.
Inaddionto1/21120 SIA loops
smalltriangularSIAclustersinthebasalplane,seeFigs.D4andZ3,anddisorderedSIAclusters,Figs.D2and
Z2areformedinthetwomaterials.TheonlydifferenceistheclusterpresentedinFig.D3thatdoesnothave
itsZrcounterpart.
The clustered vacanciesalmost inevitably formSFTlike
configuraons inCuandTiAl.The 110edgesof
theseextendeddefectsarestairrodparaldislocaonsandsotheirstrainfield
isshort rangedcompared
withthatofotherpointdefectclusters.
ThemostcommonvacancyclusterinZrandTi3Alisaprismacdislocaonloop(aloop).Aswellasmobile
SIAloopsprismacvacancyloopswereobservedinthetwomaterialsunderallsimulaoncondions.Inad
diontoaloopsasmallnumberofvacancyloopsinthebasalplace(cloops)anda+cloopswasdetectedin
Zratlowtemperatures.NocloopswereobservedinD019Ti3Alintermetalliccompound.
L10TiAl Cu
D019Ti3Al Zr
igureL1.Nearlyregularstackingfaulttetrahedron
SFT)wasformedinacollisioncascadeinTiAlinter
metallicsatT=300KandEpka=20keV
Figure L2. Two 1/2110 SIA dislocaon loops ac
companySFTformed ina20keVcollisioncascade
atT=300K
FigureC1.NearlyregularSFTformed inacollision
cascadeincopperatT=100KandEpka=25keV,see
FigureL1forcomparison.
FigureC2.Amassive1/2110SIAdislocaonloop
inthevicinityofanSFTformedatT=600K.
igureL3.Alrichdisordered SIAcluster formedat
T=300KandEpka=20keV
FigureL4.ThemeanvalueofthenumberofFren
kel pairs formed in collision cascades in the four
materialsasafunconofTandPKAenergy
FigureC3.A faulted1/3111SIA Frank loopnear
SFTlike vacancy cluster formed at T=100K and
Epka=25keV.NoFrankloopswereobservedinTiAl.
FigureC4. Threedimensional SIA clusterwith low
indexfacesformedatT=100K ina25keVcollision
cascade.NosimilarclusterswerefoundinTiAl.
igure D1. Prismac vacancy dislocaon loop
boom le) issurroundedby two1/2 1120SIA
oops.
FigureD2.Disordered SIAcluster (top right) inthe
vicinityofaprismacvacancyloop.
FigureZ1.Prismacvacancy loop in the centreof
the frame is surrounded by three 1/21120SIA
loops
FigureZ2.Disordered SIAcluster(top right) in the
vicinityofavacancy loop.Thearrangementofthe
clusters issimilartothatpresentedinFigureD2.
igureD3.AlargeSIAclusterinthebasalplane.No
imilarclusters havebeenobservedinZr.
Figure D4. Triangular 5SIAs cluster in the basal
plane(toprightcorner).
Figure Z3. Triangular 5SIAs cluster in the basal
plane.Thecluster is idencaltothatshown inFig
ureD4.
FigureZ4.Vacancy loop in thebasalplane.Crystal
lace collapses towards the vacancy agglomera
on.NosuchloopswerefoundinTi3Al.
5 10 15 20
0
20
40
60
80
N
FP
EPKA
, keV
Cu TiAl Ti3Al
Al
100K
300K
600K
900K
-Zr (no temperature
dependence)
