6. 8 Diffusion Mechani sm Flick's' law in microscopic form 1. One dimensional diffusion. jump frequency period probability of atom jumping to nearest position

Discrepancies between theory and practice in Deformation. 1. Morphology of the surface in deformation. 2. The great difference between theoretical and actual strength of single crystals (. >>)

By cottrell atmosphere model, we can explain the sharp yielding phenomenon

(for one dimensional diffusion only 1. Infinite system 1. Formula

I Atom movement in sol ids mechanical movement thermal vibration (short-range migration) Thermal motion diffusion(long-range migration)

5. 19 Reaction between Dislocation Condition 1. Geometrical condition

Back stress exerted by obstacle on leading dislocation. (It is supposed to be a short-range-force.) nrbdx =tpbdx dx virtual displacement

5.16 Dislocation in FCC crystals Perfect dislocation b =na, +nb. +nC

5. 8 The Stress Around a Dislocation 1. Screw dislocation: Displacement:

1. There have no two-phases area in diffusion area, every layer is single-phases 2. Phase's interface moves according to parabola law 3. Phase's width