T卜SA14Sn—ZZr-IMo-0.25SilNd（
卜55alloy）isaneara lphahightemperature（550C）titaniumalloy.Usin gTI—55alloyInaerospacestructuralandongIneap plicationwillbeslgnlficantfordesigningnewpt engineandimprovingairplanecharacteristics.A dditionoflwt％rareearthelementNdIntoTI—AI-Sn —Zr-Mo—SIalloysystemresultsInauniformdlstrl butlon’）fthermal-stabledlspersolds,andobvlo uslyimproveshightemperatureproperties
二5％St、l％Nd.Theal loywaspreparedbyvacuumarcmeltlnaInthefo了门lo fbuttonsofmass1000kg,whichwasremeltedthreet imesrepeatedlytoobtainhomoueneoolscompositi on.Thesize,shapeanddlstrlbutlonoftheNd-rich phaseparticleswerestunedonifNeophot—ZIoptic almicroscope.Dlstrlbutlonofelementswerecarr iedoutonanEMP—sl（）electronprobemlcroanalyze r.Thinfoilsfortransmissionelectronmicroscop e（TEM）wereprcpsfCdby！OttbC8ffithllllllllg.T hCSpCClffiCllSWCfCCX8thlllCdOilsflEM—420tfs flsttilSSIOflCICCironmicroscopewithEDAXappa ratusoperatingat100kV.2.巴6StiltSSRdmSC山88lO ll厂吧.llsanoptlcalmacroBraphoftheTI—55alloyr lser.ItlsclearthattlierearetworCLl<）！j.InFi g.l。coarsedendrltezoneandequlaxlalErainzone .Aboundarylinedl丫idestherlSof”InT（）tworegio nsduetotheshapecontrastofthearalns.Thedendr lt！ccrystalsarcif！innedpartlllel,（。thesolld lficatlondirection,fromtheboundarylinetotil erisertop.！heIntcrdelldrltlcspaclnz。decreas e二andthedendrltesarerefinedneartotheup一surf ace卜vthehlul,coollnuriftesTr。。一FlulOptlcalm acrograpllotas-castTI-55allovrlseruherethea rrowIndicatestheapproxllnatedirectiono孟soll dlficatlon一FlgZOpticalmlcrograr）hofas—castT I-55alloyInequlaxlaaralnzoneInorphologychan 臼es、fromequlaxlaltodendrltlc.areowlngtothea bruptdecreaseofthes川1山nCatlonf血edurln匹s卜rlf lh8C.一Fig.3OptiCalm口ICfogfsphOfas-CastTi-55 SlloylnCOafsedendrltesZOne回口Fig.4TEMbrl只hi门 eldofNd-fiChphascnaft1CkhFI匕SDIStrlbutlonOt NdOnsllrfaCCOfNd-riChTi55alloyphaseparticle sAnoPticalmlcrographrepresentativeoftilemic rostructureof！heas-castTI-55aloyIntheequlax lalgrainzoneIsshown！nFig.2.ThesecondphasePa rtlc卜sare2刀～25lllnInd！ametCf.soffiCpsftlC卜S dppCflftitt卜egF8lflbollfldflflCS,thCO艺hCfSp FCClpltdtCWltll！nthCgfdlfls.T卜cshaPesofthes epartlclesaremalnlyelllpsoids、anda几wkindsof shortneedle-likeandblockvmorphologies.Bands ofsecondpllascparticlesarefoundInthedendrlt lccrystalzoneasshownInFig.3.ComparingFig二wi thFig.3.thesizeoftheparticlesIsoftilesallle orderofInagll！tildeTilerowsofsecondphasepar tlc卜sarenormaltothedendrltlc＂rainboundary., .’’.thebandsofpartlclesareall川ledParallelto tilead\anclll只solldjncatlon＂out、dePelldlnXo ntileInterfaceVCIOClty.Attll。pittoldOOtlf}t ile。tr;IctureOfth。。。to。idPlllSSPPI·tlCIC。by LI。11。gX-11\SPCCtfOSCOPC1llCflotSllCCCSStLl l,1>I·CSLlllldblybCCdUhCO厂thCIc\\O\CldllCOl lCCflt！lit！OfffllNd（l0Wt）.Fig.4SllOOSthtTEM if卫ugtOftllCis-CChtTI-5）Illoy.It11ClcCI·tll lttile1llttl·t三ICcbetweentheTImatrixandpart icleIsfaceted.TheparticleIspolylaQeralspher ewhichIsmadeofinetlnlformdarkspotsandlargev olumefractionsofbrluhtanddarkregion.Thedi回1 actionpatternoftheecondphaseparticleIssocom plexthatItcannotbeIndexed.TheelectronInlcro proberesultsshowthattheparticlesarerichInNd .SnandOasshowninFigs.5、6and7。respectively.E DAXresultsoftheparticlesareNd/Sn（at％）一l—3.a ndthevaluesofNd/SnchangewithdlffeFCFCntregi onsIntheparticles.theparticlescannotbecompa tiblewithaixedphaseorcompound.SoItcannotbec oncludedtemporarilywhat！heparticlesareexact ly,onlyaccodlngtothedlffrffractlonpattern、E DAXandelectronmlcroptoberesultsoftheparticl es.However,thesepreliminaryesultssuggesttha ttheparticlescanbedenotedastheNd—richphase. 口回Fb.6口幻h6m1m叨3n。＊s皿h一n7m响他unonion吐0——皿颅皿Ti—NdbelongstoaclassofsysttIYlsInwnlcnmeelements！enQtostronalvreoel_eachotheLresultln二Inllauld口baseimmis一5“0’NI.I三k三回三。___】__.2。L__
More abstracts about the DISTRIBUTION OF Nd-RICH PHASE PARTICLES IN AS-CAST Ti-5Al-4Sn-2Zr-1Mo-0.25Si-1Nd ALLOY