简介:Thesimulationofnanoindentationintosinglenickelcrystalisperformedbyusingquasicontinuummethod.Thestrainenergy-displacementandload-displacementcurvesarepresentedtostudythemechanicalbehaviorofthedislocationnucleation.Thecharacteristicsofthestackingfaultanddislocationnucleationaredeterminedbycalculatingthecentro-symmetryparametersandanalyzingthedisplacementfieldoftheatomsbeneaththeindenter.Thestructureofthestackingfaultandthecharacteristicsofdislocationobtainedinthesimulationbyquasicontinuummethodarereproducedinthesimulationbymoleculardynamics.
简介:阶段地水晶(陆军)模型被用来模仿premelting脱臼运动对称当系统温度在时,在紧张行动下面倾斜谷物边界(STGB)远非,到融化的融化的点和结束分别地指。结果证明当premelting温度被接近到,本地premelting发生包围脱臼从在温度下面。STGB的premelting脱臼能在紧张行动下面滑行,并且premelting区域是为脱臼滑行的一个同伴。STGB腐烂的过程以二个高温度条件是很类似的。当premelting介绍,它减少为脱臼的滑行抵抗并且导致脱臼的一个更快的运动,并且也在STGB的腐烂过程期间引起系统的更多的精力减小。尽管有把紧张用于这些,premelting在STGB的整个腐烂过程取样,premelting脱臼区域显然不发展并且延长。这显示外部紧张行动不在高温度支持premelting,并且不能导致更多的premelting脱臼,它能在脱臼展览附近被欠到premelting阶段像液体的性质并且到容易滑行并且放松紧张精力的premelting脱臼;这与实验和分子的动力学的结果一致。
简介:Theinternalstressinducedbyaporouslayerorpassivelayercanassisttheappliedstresstopromotedislocationemissionandcrackpropagation,e.g.whenthepipelinesteelisburiedinthesoilcontainingwater,resultinginstresscorrosioncracking(SCC).Moleculardynamics(MD)simulationisperformedtostudytheprocessofdislocationemissionandcrackpropagationinaslabofFecrystalwithandwithoutaporouslayeronthesurfaceofthecrack.Theresultsshowthatwhenthereisaporouslayeronthesurfaceofthecrack,thetensilestressinducedbytheporouslayercansuperimposeontheexternalappliedstressandthenassisttheappliedstresstoinitiatecracktipdislocationemissionunderloweredstressintensityKI,orstress.Torespondtothecorrosionaccelerateddislocationemissionandmotion,thecrackbeginstopropagateunderloweredstressintensityKI,resultinginSCC.
简介:Usingaspecialconstantdeflectiondevice,thechangesindislocationconfigurationaheadofaloadedcracktipfor60Fe40Nialloy,beforeandaftermagnetizationinamagneticfield,havebeenstudiedinTEM.Theresultsshowedthatthemagnetizationfor60Fe40Nialloycouldenhancedislocationemission,multiplicationandmotion.Also,themechanicalpropertiesof60Fe40Nialloy,inairandinthemagneticfieldrespectively,havebeeninvestigatedusingtheslowstrainratetension.Andtheresultsindicatedthatmagnetizationcouldmaketheyieldstrengthcorrespondingtodecreaseby26percent,butdidnotinfluencetheultimatetensilestrengthandthefracturestrain,whichshowedthatmagnetizationcouldenhanceplasticdeformation.