清华材料科学基础课件(英文)skja_14课件

《清华材料科学基础课件(英文)skja_14课件》由会员上传分享，免费在线阅读，更多相关内容在教育资源-天天文库。

1、材料科学基础FundamentalofMaterialsLessonfourteen2021/10/2材料科学基础§4.4RotationofCrystalduringSlipⅠ.Thecauseofrotation:Duetoconstraints,orboundaryconditions,imposedonthecrystal.Ⅱ.Theruleofrotation:1)axisofrotation∥∥2021/10/2材料科学基础2)Duringslip,theS.D.tendstoapproachtoloadi

2、ngdirectionintension.Duringslip,theS.P.tendstoapproachtocompressionplaneincompression.FFFFFFFF2021/10/2材料科学基础2021/10/2材料科学基础Ⅲ.Theconsequenceofrotation:1.ChangeinlengthofthespecimenIntensionIncompression2021/10/2材料科学基础②GeometricalsofteningintensionSchmid’slawatth

3、eonsetofslip:2.Changeinorientation①Orientationchangeandmultislip2021/10/2材料科学基础Example:Given:aFCCcrystalheldintension∥Determine:1.Singleslipsystem2.Ruleofrotation3.andorientationattheonsetofduplexofslip4.Ruleofrotationduringduplexslip5.Finalorientation,i.e.thest

4、ateposition2021/10/2材料科学基础slipsystem:locus:Ftendto,∥∥Solution:2021/10/2材料科学基础stable:2021/10/2材料科学基础§4.5SurfaceMorphologyofCrystalAfterSlipThefollowingdeformationmarkscanbeseenonthesurfaceofthecrystalafterslip.Sliplines:thestepsformedonsurfaceduetoslip.Slipbands.

5、Deformationbandformedduetoinhomogeneousrotation.Kinkbands2021/10/2材料科学基础§4.6StrainHardening(Work-hardening)Ⅰ.What’sstrainhardening?(workinghardening)Bystrainhardeningwemeanstheincreaseintensilestressforpolycrystalsorinshearstress(theflowstress)forsinglecrystalsn

6、ecessaryforkeekingonplasticdeformation.2021/10/2材料科学基础Theshearstrainnecessaryforsliptocontinueincreaseswiththeamountofshearstrain.ThisPhenomenoniscalledstrainhardeningorworkhardeningofsinglecrystal.2021/10/2材料科学基础StrainHardeningcurveofsinglecrystal——curve.Itcanb

7、edividedintothreestages:forⅠ:Easy-glideforⅡ:LinearhardeningisverygreatforⅢ:Parabolichardening↓flowstressIⅡⅢⅡ.HardeningCurve1.Characteristicofhardeningcurve2021/10/2材料科学基础Howtoobtaincurve①②③④2021/10/2材料科学基础Ⅲ.SurfaceMorphologysliplineslipbandcrosssliplineandbandsl

8、ipband——滑移带deformationband——形变带rinkband——弯折带2021/10/2材料科学基础§4.7Twinning(Ⅰ)——MicroscopicAspectⅠ.Basicfeatureoftwinnings.Twinningisatranslationalmovementsofoneportionof