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1、NanoStructuredMaterials,Vol.11,No.8,pp.1017±1029,1999ElsevierScienceLtdPergamonCopyright©2000ActaMetallurgicaInc.PrintedintheUSA.Allrightsreserved.0965-9773/99/$±seefrontmatterPIIS0965-9773(99)00383-9DEFORMATION-INDUCEDNONEQUILIBRIUMGRAIN-BOUNDARYPHASEINSUBMICROCRYSTALLINEIRONV.A.Shabashov*,V.
2、V.Ovchinnikov**,R.R.Mulyukov***,R.Z.Valiev****andN.P.Filippova**InstituteofMetalPhysics,UralBranchofRAS,18S.KovalevskayaSt.,620219Yekaterinburg,Russia**InstituteofElectrophysics,UralBranchofRAS,34KomsomolskayaSt.,620049Yekaterinburg,Russia***InstituteforProblemsofMetalSuperplasticity,UralBranc
3、hofRAS,39KhalturinSt.,450093Ufa,Russia****UfaStateTechnicalUniversityofAviation,ul.K.Marksa12,Ufa,450025,Russia(ReceivedNovember7,1997)(AcceptedAugust15,1999)AbstractÐTheshapesofMoÈssbauerspectraofcoarse-grainedannealedarmcoironandsubmicrocrystalline(SMC)ironwithagrainsizeof0.22mmwerecompared.
4、TheSMCwasmadefromthearmcoironbypressureshearandsubsequentannealingat420°C.Weintendedtoseparateanadditionalsubspectrum,whichappearsasaresultofthegrainrefinement.Thatsubspectrumwasattributedtograin-boundaryatomsortheªgrain-boundaryphaseº(GBP).Thevolumefractionofthatphasewasdetermined.Ontheaverag
5、e,theGBPinteratomicspacingwassuggestedtobe1%largerthanthatofthegrainphase(GP)andthepresenceofconsiderablecompressivestressesintheGBPwerededuced.Apossiblereasonforthesatellitesubspectrumappearingafterthegrainrefinementwasthatitwasattributedtoasuddenchangeinthefundamentalcharacteristicsofthesoli
6、datacertaincriticalvalueofthelatticeparameter,whichvariescontinuouslyingoingfromthegeometricalboundarytothegraincenter.©2000ActaMetallurgicaInc.1.IntroductionTheMoÈssbauerspectroscopystudiesofsubmicrocrystalline(SMC)materials[1±9],whichpossessunusualproperties,haverecentlyprovidedverysignifica
7、ntnewdatapertainingtothelocationofnonequivalentsitesofgrain-boundaryandgrainatomshavingdifferentelectronic(specificallymag-netic)structures,dynamicproperties,etcetera.TheauthorsofoneofthepioneeringpapersdealingwiththeMoÈssbauerstudyofSM