剪切载荷条件下镍基单晶合金裂纹扩展与微观结构演化行为研究（英文）

剪切载荷条件下镍基单晶合金裂纹扩展与微观结构演化行为研究（英文）Research on Crack Propagation and Microstructure Evolution Behavior

剪切载荷条件下镍基单晶合金裂纹扩展与微观结构演 化行为研究（英文） ResearchonCrackPropagationandMicrostructureEvolution BehaviorofNickel-BasedSingleCrystalAlloyunderShearLoad Condition Introduction Nickel-basedsinglecrystalalloyshavebeenwidelyusedin high-temperature,high-stressenvironments,suchasgasturbine engines,duetotheirexcellentmechanicalpropertiesand high-temperaturecreepresistance.However,thesafetyand reliabilityofthesealloysaregreatlyaffectedbythefatiguecrack propagationbehaviorandmicrostructureevolutionunder complexloadingconditions.Thispaperaimstoinvestigatethe crackpropagationbehaviorandmicrostructureevolutionof nickel-basedsinglecrystalalloysundershearloadconditions. ExperimentalProcedure Theexperimentalmaterialusedinthisstudyisanickel-based singlecrystalalloy.Thesheartestwasconductedusingamodified four-pointbendingtest.Thetestspecimenwasloadedacrossthe widthunderaconstantdisplacementrateuntilthefracture occurred.Duringthetest,thecracklengthandtheloadwere recordedcontinuously.Afterthetest,themicrostructurewas observedandanalyzedthroughscanningelectronmicroscopy (SEM)andtransmissionelectronmicroscopy(TEM). ResultsandAnalysis Theexperimentalresultsshowthattheshearfractureof nickel-basedsinglecrystalalloysischaracterizedbytheinitially quasi-plasticdeformationandthefinalbrittlefracture.Thecrack propagationbehaviorundershearloadconditionscanbedivided intothreestages. Stage1:Elasticstage Intheinitialstage,thesheardeformationwasaccompanied byaslightdeflectionofthedislocations,andtheaspectratioof theorderedγ'precipitatesdecreasedslightly.Theelastic