Diffusion-induced stresses and their relaxation

Possible origins of diffusional stress-free strains and their effects on interdiffusion are treated. Experimental examples of such stress effects (change of the growth rate, bending, failure of wires with coatings, stabilization of multilayers) are exposed and explained. Results of computer simulations, carried out on the basis of Stephenson’s coupled equations, are also presented. It is shown that both the “gradient” (the presence of a new term proportional to the stress gradient) and “mobility” (the pressure dependence of the diffusion coefficients) effects can be important. Special features of the above phenomena on nanometre length scale are also considered.