The effect of stress on grain boundary interdiffusion in a semi-infinite bicrystal

Chemical interdiffusion along a grain boundary in a semi-infinite bicrystal subjected to external stress normal to the boundary plane is considered. Plating out of diffusing atoms in the grain boundary partially relaxes the applied stress and modifies the driving force for diffusion. The resulting diffusion wedge formed at the grain boundary exhibits a time-independent shape, with all its linear dimensions growing with annealing time t, according to the t1/3 law. The diffusion zone formed in the vicinity of the grain boundary is a combined result of the grain boundary diffusion and lattice drift, and is characterized by concentration discontinuities at its borders. The proposed model is applied to the analysis of liquid metal embrittlement in the Fe–In and Cu–Bi systems.