清华大学：《材料科学基础》课程教学资源（PPT课件讲稿）Chapter 6.1 Introduction

3. According to diffusion path o Volume diffusion (with grain, or lattice) (2 Grain boundary diffusion ③ Surface diffusion short-cut diffusion a diffusion along dislocation 4. According to structure Diffusion in single phase Diffusion in multiphase

① Volume diffusion (with grain, or lattice) ② Grain boundary diffusion ③ Surface diffusion short-cut diffusion ④ diffusion along dislocation Diffusion in single phase Diffusion in multiphase

lll Significance heat treatment, welding, sintering, corrosion IV. Content phenomenological theory I microscopic theory

heat treatment , welding , sintering , corrosion phenomenological theory microscopic theory

§6.2 Fick s Laws 1.Fick’ s first aw 界面 C1,均为固定值 For binary; single-phase system△m∝ aC A△t OX lim An__DaC A diffusion flow dt m D diffusion flux Adt

For binary, single-phase system A t x C m      diffusion flux d d lim diffusion flow d d 0 — — x C D A t m J A x C D t m t m t               界面 x C2 C1 C2 > C1，均为固定值