A front-tracking finite difference approach was used to investigate the effect of misfit strains and applied stresses upon interdiffusion in binary coherent 2-phase planar diffusion couples, under the assumption of local thermodynamic equilibrium at the interface. The phases were cubic, had various lattice parameters, elastic constants, and diffusivities, and could be oriented in the [001] or [111] direction. It was found that the interface compositions, which were independent of time in the stress-free case, became time-dependent when stresses were present. They were affected by both the elastic state of the system and by the relative diffusivities. The interfacial compositions could vary by up to a few atomic percent, with time, and could be greater or less than the stress-free values for a given set of materials parameters; depending upon the volume fractions of the phases. At sufficiently short times, the interfacial position could be approximated as being proportional to the square root of time. The interfacial velocities in this region could differ, by up to a factor of 2, with respect to an otherwise equivalent unstressed system. The non-linear equations which resulted from the coupling of stress and composition were linearized in the bulk phases, and could be solved implicitly or explicitly.

W.C.Johnson: Metallurgical and Materials Transactions A, 1997, 28[1], 27-38