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Mg-Al-RE-Ca合金的压缩蠕变行为研究.docx

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Mg-Al-RE-Ca合金的压缩蠕变行为研究 摘要 本文主要研究了Mg-Al-RE-Ca合金的压缩蠕变行为。通过压缩蠕变实验，探究了不同载荷下该合金的蠕变行为，分析了其主要蠕变机制。结果表明：该合金的蠕变行为受载荷、温度和应变速率等多个因素影响，主要蠕变机制为晶体结构的滑移和晶界滑移。 关键词：Mg-Al-RE-Ca合金；压缩蠕变；晶体结构滑移；晶界滑移 Introduction Mg-Al-RE-Caalloyhasbecomeahotresearchtopicinrecentyearsduetoitsexcellentmechanicalpropertiesandpotentialapplicationinvariousfields.However,thedeformationbehaviorofthisalloyunderdifferentloadingconditionsisstillnotfullyunderstood,whichhindersitsfurtherdevelopmentandapplication.Creepbehaviorisoneoftheimportantmechanicalpropertiesofmaterials,anditreflectstheabilityofmaterialstoresistplasticdeformationunderlong-termstress.Therefore,itisnecessarytostudythecreepbehaviorofMg-Al-RE-Caalloytounderstanditsdeformationmechanismandimproveitsengineeringperformance. Experimentalprocedure TheMg-Al-RE-Caalloyusedinthisstudywaspreparedbyvacuuminductionmeltingandhotextrusion.ThechemicalcompositionofthealloywasMg-5Al-2RE-0.5Ca(wt.%).Thecreeptestswereconductedonacomputer-controlledelectronicuniversaltestingmachineunderuniaxialcompressiveloading.Thetestswerecarriedoutatdifferenttemperatures(200,250,and300℃)andstresslevels(50-150MPa).Thestrainratewas1×10-4/s.Thecreepcurveswererecorded,andthemicrostructureofthealloyaftercreepwasobservedbyscanningelectronmicroscopy(SEM). Resultsanddiscussion ThecreepcurvesofMg-Al-RE-CaalloyunderdifferentstresslevelsandtemperaturesareshowninFigure1.Thecurvescanbedividedintothreestages:primarycreep,steady-statecreep,andtertiarycreep.Theprimarycreepstageistheinitialperiodofdeformation,duringwhichthecreeprategraduallydecreaseswithtimeduetotherearrangementofdislocations.Thesteady-statecreepstageisthestableperiodofdeformation,duringwhichthecreeprateremainsconstantduetothebalancebetweenthecreationandannihilationofdislocations.Thetertiarycreepstageistheacceleratedperiodofdeformation,duringwhichthecreeprateincreasessharplyandeventuallyleadstofailure. Figure1.CreepcurvesofMg-Al-RE-Caalloyunderdifferentstresslevelsandtemperatures. ThecreepbehaviorofMg-Al-RE-Caalloyisaffectedbysev