Phase field modelling of diffusion induced grain boundary migration in binary alloys.

The Phase field method has been used to study Diffusion Induced Grain boundary Migration (DIGM) in binary alloys. Simulations are performed for a simple hypothetical binary substitutional solid solution. The model is developed by taking into account the elastic interactions arising due to changes in concentration across a grain boundary when solutes are diffusing along the grain boundary. This gives a coupling term in the Gibbs energy functional that acts as a driving force for grain boundary migration. Two different kinds of coupling terms are studied: one acting on both the abutting grains and the other acting on only one grain. The former gives a freedom of choice as to in which direction the grain boundary will move, and is considered more general, whereas the latter only moves in one direction, regardless of the shape of the grain boundary. The results from the model are in qualitative agreement with previous experimental studies.