ch2位错-2.4位错与晶体缺陷作用详解.ppt

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1、2021/2/71Ch2位错2.1位错理论的产生2.2位错的几何性质2.3位错的弹性性质2.4位错与晶体缺陷的相互作用2.5位错的动力学性质2.6实际晶体中的位错2021/2/722.1位错理论的产生一、晶体的塑性变形方式二、单晶体的塑性变形三、多晶体的塑性变形四、晶体的理论切变强度五、位错理论的产生六、位错的基本知识2021/2/732.2位错的几何性质一、位错的几何模型二、柏格斯矢量三、位错的运动四、位错环及其运动五、位错与晶体的塑性变形六、割阶2021/2/742.3位错的弹性性质一、弹性连续介质、应力和应变二、刃型位错的应力场三、螺型位错的应力场四、

2、位错的应变能五、位错的受力六、向错七、位错的半点阵模型2021/2/752.4位错与晶体缺陷的相互作用一、位错间的相互作用力二、位错与界面的交互作用三、位错与点缺陷的交互作用2021/2/76InteractionsBetweenDislocationsWewillfirstinvestigatetheinteractionbetweentwostraightandparalleldislocationsofthesamekind.Ifwestartwithscrewdislocations,wehavetodistinguishthefollowingca

3、ses:2021/2/77Inanalogy,wenextmustconsidertheinteractionofedgedislocations,ofedgeandscrewdislocationsandfinallyofmixeddislocations.Thecaseofmixeddislocations-thegeneralcase-willagainbeobtainedbyconsideringtheinteractionofthescrew-andedgepartsseparatelyandthenaddingtheresults.Withthe

4、formulasforthestressandstrainfieldsofedgeandscrewdislocationsonecancalculatetheresolvedshearstresscausedbyonedislocationontheglideplaneoftheotheroneandgeteverythingfromthere.Butforjustobtainingsomebasicrules,wecandobetterthanthat.Wecanclassifysomebasiccaseswithoutcalculatinganythin

5、gbyjustexaminingoneobviousrule:Ifthesuperpositionofthestrainfieldsofdislocationsadduptovaluesofthecompressiveortensilestrainlargerthanthoseofasingledislocations,theywillrepulseeachother.Ifthecombinedstrainfieldislowerthanthatofthesingledislocation,theywillattracteachother.2021/2/78

6、Thisleadstosomesimplecases:1.Arbitrarilycurveddislocationswithidenticalbonthesameglideplanewillalwaysrepeleachother.2021/2/792.ArbitrarydislocationswithoppositebvectorsonthesameglideplanewillattractandannihilateeachotherEdgedislocationswithidenticaloroppositeBurgersvectorbonneighbo

7、ringglideplanesmayattractorrepulseeachother,dependingontheprecisegeometry.Thebluedoublearrowsinthepicturebelowthusmaysignifyrepulsionorattraction.2021/2/710ThegeneralformulafortheforcesbetweenedgedislocationsinthegeometryshownaboveisFx= [Gb2/2p(1–n)] · [x·(x2–y2)/(x2+y2)2]Fy= [Gb2/

8、2p(1–n)] ·[y·(3x2+y2)/(x2+