内部摩擦研究fcchcp马氏体

MaterialsScienceandEngineeringA442(2006)404–408Internalfrictionstudyonfcc/hcpmartensitictransformationsinthermomechanicallytreatedFe–28Mn–6Si–5Cr–0.53Nb–0.06C(mass%)alloysZ.Donga,1,T.Sawaguchia,∗,T.Kikuchia,F.Yina,K.Ogawaa,P.Sahub,2,S.KajiwaraaaNationalInstituteforMaterialsScience,Tsukuba305-0047,JapanbIndianAssociationfortheCultivationofScience,Jadavpur,Kolkata700032,IndiaReceivedinrevisedform2March2006;accepted6March2006AbstractWehavestudiedthetemperaturedependenceoftheinternalfrictionandYoung’smodulusoftheFe–28Mn–6Si–5Cr–0.53Nb–0.06C(mass%)alloyswithorwithoutNbCprecipitatesproducedbythreethermomechanicaltreatments:(i)solutiontreatment,(ii)rollingat870Kandsubsequentagingat1070K,and(iii)rollingat1070K,inthevicinityoftheforward(Ms)andthereverse(As)martensitictransformationtemperaturesusingadynamicmechanicalanalyzer(DMA).Thespecimensubjectedtorollingat870KandsubsequentagingshowedthehighestMstemperatureandthelargestamountofthehcpmartensite.ThesolutiontreatedspecimenshowedthelowestMstemperatureandtheminimumamountofthemartensite.Themagneticsusceptibilitymeasurementsmadebymeansofasuperconductingquantuminterferencedevice(SQUID)revealedthatthemartensitictransformationishinderedbytheprecedingmagnetictransitionfromtheparamagnetic(cubic)phasetotheantiferromagnetic(tetragonal)phase.©2006ElsevierB.V.Allrightsreserved.Keywords:Fe-basedshapememoryalloy;NbCcarbide;Martensitictransformation;Internalfriction;Antiferromagnetictransition1.IntroductionFe–Mn–Si-basedalloysarewellknownlowcostshapemem-oryalloys(SMAs)[1],whichshowone-wayshapememoryeffect(SME)associatedwiththestress-inducedmartensitictransformationfromthefccaustenite()tothehcpmarten-site()anditsreversionbysubsequentheating.TheSMEcanbeimprovedbyaspecialthermomechanicaltreatmentcalled“training”,whichconsistsofseveralcyclesofslightdeforma-tionandsubsequentshaperecoverybyheating[2].Kajiwaraetal.foundthattheadditionofNbandCsignif-icantlyimprovestheSMEofFe–Mn–Si-basedSMAswithoutbeingsubjectedtothetrainingtreatment[3,4].FineNbCcar-bidesdispersedintheausteniteareconsideredtoprovidenucle-∗Correspondingauthor.Tel.:[phone];fax:[phone].E-mailaddress:[e-mail](T.Sawaguchi).1Presentaddress:SwissFederalLaboratoriesforMaterialsTestingandResearch(EMPA),CH-8600Dubendorf,Switzerland.2Presentaddress:NationalMetallurgicalLaboratory,Jamshedpur831007,India.ationsitestothemartensiteplates,andthestressfieldsaroundthemfavorthereversetransformation,therebyimprovingtheSME.Moreover,itwasalsofoundthatpre-deformationspriortotheagingtreatmentsareeffectiveforfurtherimprovementoftheSME[5–11].Earlierstudieshaveestablishedthatthemarten-siteplatesformedinthealloysbyappliedstressareextremelythin(nano-scale)andareofasinglevariant.Thismicrostructuralfeatureisverysimilartothatoftrainedalloys,andisconsideredtofacilitatethereversiblemovementofthe/interfaces[12].Veryrecently,internalfrictionstudiesusingadynamicmechanicalanalyzer(DMA)werecarriedoutonathermome-chanicallytreatedFe–28Mn–6Si–5Cr–0.53Nb–0.06C(mass%)alloy[13].Itwasfoundthatthealloyshowsaninternalfric-tionpeakateachofforward(Ms)andreverse(As)martensitictransformationtemperatures.Theheightofthepeakisdepen-dentonstrainamplitudebutindependentofvibrationfrequency.Thealloyexhibitsasignificantdampingcapacityatlargerstrainamplitudesandcanbeutilizedasahighseismicdampingalloy.Inthepresentpaper,wereporttheeffectofthermomechani-caltreatmentsontheinternalfrictionofthealloyofthesamenominalalloycomposition:Fe–28Mn–6Si–5Cr–0.53Nb–0.06C0921-5093/$–seefrontmatter©2006ElsevierB.V.Allrightsreserved.doi:10.1016/j.msea.2006.03.116Z.Dongetal./MaterialsScienceandEngineeringA442(2006)404–408405(mass%),forbetterinterpretingtheeffectofthermomechani-caltreatmentsonthemartensitictransformation.Thetemper-aturevariationofinternalfrictionandYoung’smoduluswasmeasuredintwoconditions:withorwithoutNbCprecipitates,dependingonthethermomechanicaltreatment.Theeffectofthethermomechanicaltreatmentsontheinternal-structuresandonthemartensitictransformationbehaviorisdiscussed.Along-side,fromthemagneticsusceptibilitymeasurementsusingasuperconductingquantuminterferencedevice(SQUID)mag-netometer,itwasalsofoundthat,inthisalloycomposition,anantiferromagnetictransitionoccursinthevicinityoftheMstemperature.2.ExperimentalprocedureAnFe–28Mn–6Si–5Cr–0.53Nb–0.06C(mass%)alloywaspreparedbyvacuuminductionmelting.Afterhot-forgingandrolling,asolutiontreatmentwascarriedoutat1470Kfor10hinargonatmosphere.Inthiscondition,niobiumandcarbonareconsideredtoexistassubstitutionalandinterstitialsoluteatoms,respectively.Thentwothermomechanicaltreatmentswereper-formedinordertoproducefineprecipitationofNbCcarbides.Onecomprisedawarm-rollingof14%reductionincrosssec-tionalareaat870Kandsubsequentagingat1070Kfor10min.Theotherconsistedofahot-rollingof14%reductionincrosssectionalareaat1070K.Thespecimenssubjectedtothethreetreatmentsarereferredtoas“ST”,“R870”and“R1070”.Barujetal.[6,7]andKajiwara[11]indicatedthattheR870speci-menshowsagoodSMEcomparabletothatobtainedintheconventionalFe–Mn–Si-basedSMAssub