清华大学lesson 29：复习资料

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1、材料科学基础材料科学基础FundamentalofMaterialsFundamentalofMaterialsFundamentalofMaterialsFundamentalofMaterialsProf:TianMinBoTel:62795426，62772851E-mail:tmb@mail.tsinghua.edu.cnDepartmentofMaterialScienceandEngineeringTsinghuaUniversity.Beijing100084Lessontwenty

2、-nine§§6.7ReactionDiffusion(Diffusion6.7ReactionDiffusion(DiffusioninMultiplePhaseZone)inMultiplePhaseZone)�ⅠⅠ.Courseofreactiondiffusion.Courseofreactiondiffusiondiffusionphasechange1.Therehavenotwo-phasesareaindiffusionarea,everylayerissingle-phases.

3、2.Phase’sinterfacemovesaccordingtoparabolalaw.3.Phase’swidthⅡⅡ.Basicfeatures:.Basicfeatures:1.Diffusionisaccompaniedbyreactionorphasetransformation.Ingeneral,diffusionisrate-determiningstepwhilereactiontakeplaceinstantaneously.2.Fordiffusioninbinarysy

4、stemsthereappearonlyaseriesofsinglephase,oneadjacenttoanother,whilemixedphasezonedoesn’tappear.3.Concentratingchangesabruptlyatphaseboundary.4.Thephaseboundariesandthewidthofeachphasechangeparabolicallywithtime.�ⅢⅢ..ReactionDiffusionReactionDiffusiond

5、ynamicsdynamics1.Speedofinterface⎡∂C∂C⎤(−D)−(−D)dt=(C−C)⋅dx⋅1⎢∂xβα∂xαβ⎥βααβ⎣⎦∂C∂C(D)−(D)dx∂xαβ∂xβα∴=dtC−Cβααβxletλ=t∂C1dC=∂xtdλdCdC(D)−(D)dxdtαβdtβα11∴=⋅=K(C)dtCβα−Cαβtt∴x=t⋅K′(C)2.PhasewidthW=x−xββαγβdWdxdxAββαγββ=−=dtdtdttW=BtββW=x−x=Btjj,j+1j−1,jj3

6、.Ruleofphaseappearing�ⅣⅣ.Discussion.Discussion1.Phasesthatcanappear22.Growthlaw:ingeneralW=K(C)t(1)ninspecialcases:x=K(C)tn=1～4(1)istenableinvolume(lattice)diffusionfactorsinfluencinggrowth:a.Diffusionpath(latticegrainboundariesporesurface).b.Relative

7、rateofdiffusionandreactionExamplesandExamplesandDiscussionsDiscussions1.F-N2.F-CExerciseExercise（更多考研考博资料（更多考研考博资料博宸客博宸客服服扣扣：扣扣：924527819924527819924527819924527819924527819924527819924527819924527819））Thankyou!Thankyou!2929