Diffusion and Stresses
The problem of the interrelationship between diffusion and stresses is as old as the investigation of diffusion itself. Crack formation during surface oxidation, stress-induced diffusion (creep, Gorsky-effect) and the macroscopic deformation of diffusion couples during interdiffusion are well-known classical examples.
From a theoretical point of view, there are special peculiarities attached to this problem: the effect of stress fields upon diffusion cannot be treated as a primary cross-effect, but instead links the stress dependencies of the chemical potentials. Thus, the results should depend upon the density and distribution of sources and sinks, and upon the boundary conditions. The latter expectation is related to the fact that atomic currents are local phenomena, while elastic interactions have a long-range character.
In addition to the theoretical interest, it has an increasing importance in many practical applications. In thin films and multilayers, theory and experiment have an especially close relationship and their interaction increases the efficiency of the research. Investigations of reaction- or diffusion-controlled phase formation in massive diffusion samples (shape effects) also appear to be promising.