A molecular-dynamics method for simulating the intrinsic migration behavior of individual flat grain boundaries was presented. A constant driving force for grain-boundary migration was generated by imposing an anisotropic elastic strain on a bicrystal so that the elastic-energy densities in the 2 halves were different. For the model case of a large planar unit cell, high-angle (001) twist boundary in Cu, it was demonstrated that the drift velocity was proportional to the applied driving force. This permitted the determination of the boundary mobility. The activation energy for grain-boundary migration was found to be distinctly lower than that for grain-boundary self-diffusion. A decrease in the related activation energies, with increasing temperature, was shown to arise from a cross-over in the underlying mechanisms; from solid-like at low temperatures to liquid-like at high temperatures. This was accompanied by an underlying grain-boundary structural transition.

On the Relationship between Grain-Boundary Migration and Grain-Boundary Diffusion by Molecular-Dynamics Simulation. B.Schönfelder, P.Keblinski, D.Wolf, S.R.Phillpot: Materials Science Forum, 1999, 294-296, 9-16