γMNFE基合金双程形状记忆效应和磁诱发应变机制探索

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1、上海交通大学硕士学位论文γMnFe基合金双程形状记忆效应和磁诱发应变机制探索姓名：张金金申请学位级别：硕士专业：材料科学指导教师：张骥华20070124γMnFe合金具有热弹性马氏体，预应变可以使得马氏体变体择优取向，从而获得较大的应变回复。双程形状回复始终小于单程形状回复量，高锰MnFe合金双程形状记忆效应，与NiTi、CuZnAl合金不同的是，双程形状回复率达到100%，而且预应变1.6%试样在50次热循环之后双程形状回复保持不变，而且马氏体转变点保持不变。对磁诱发应变的研究，主要通过测量中锰含量的MnFe合金

2、反铁磁奥氏体相和高锰的反铁磁马氏体孪晶相的两种合金在-1.0T~0~+1.0T磁场下加载和卸载过程的应变曲线变化，多晶合金在预压条件下，外加磁场诱发宏观应变，是由于压应力使得磁畴择优取-3向重排。当预压-200ppm时磁诱发应变达到10。轧制试样的磁诱发应变比普通多晶试样的磁诱发应变大一倍。而且在轧制后退火试样中发现无预压条件下外加磁场诱发正应变是由于轧制形成磁性织构，磁畴取向择优重排，磁畴尺寸在退火后变大。关键字：γMn基合金，双程形状记忆效应，孪晶，磁诱发应变THEINVESTIGATIONOFTHETWO-W

3、AYSHAPEMEMORYEFFECTANDTHEMAGNETICFIELDINDUCEDSTRAINOFγMNFEALLOYABSTRACTMn-richγMnFealloyshaveanti-ferromagnetictransitionandFCC-FCTmartensitictransformation,andtheyhappenapproximatelyinthesametemperaturewithaproductionofFCTthermal-elasticmartensitictwins.Thism

4、akesthehigh-dampingpropertyandshapememoryeffectcometrue.Also,thecorrelationbetweenanti-ferromagnetictransitionandmartensitictransformationdeterminesthenon-hysteresisinshapemeoryeffect.So,itmakessignificantsensesforapplicationinactuationandcontrollingfieldstofo

5、cusontheresearchoftwo-wayshapememoryeffectmechanismsofγMnFealloyanddevelopthestabletwo-waystrainresponses.-3Inadditiontoshapememoryeffect,γMnFealloysalsoshowupto10straininducedbyalowmagneticfield.Itisalsoattractiveforengineersthatanti-ferromagnethasnomagnetism

6、,butcanshowupmacro-straininducedbyalowmagneticfield,whichgivesitmoreapplicationsthanferromagneticshapememoryalloysandmagnet-strictionmaterials.So,itisveryusefultoclearupthemechanismsofmagneticfieldinducedstraininγMnFealloyanddevelopitsstablestrainresponsesfitf

7、orengineeringenvironments.Therearetwopartsinthepaper:investigationoftwo-wayshapememoryeffectandinvestigationofmagneticfieldinducedstrainmechanism.Theeffectsofpre-strainsandseveraltrainingsonthetwo-wayshaperecoveryhavebeeninvestigatedthroughthermal-expansionmet

8、hod.Onewayofcalculatingtherecoverystrainsandrecoveryratioshasbeenproposed.Accordingtopriorresearchonthemicro-structuresofγMnFealloy,itisbelievedthatthetweed-structureexistingjustaf