Grain boundary self-diffusion in Ni: Effect of boundary inclination

We examined the influence of the boundary plane on grain-boundary diffusion in Ni through a series of molecular dynamics simulations. A series of < 010 > Sigma 5 tilt boundaries, including several high symmetry and low symmetry boundary planes, were considered. The self-diffusion coefficient is a strong function of boundary inclination at low temperature but is almost independent of inclination at high temperature. At all temperatures, the self-diffusion coefficients are low when at least one of the two grains has a normal with low Miller indices. The grain boundary self-diffusion coefficient is an Arrhenius function of temperature. The logarithm of the pre-exponential factor in the Arrhenius expression was shown to be nearly proportional to the activation energy for diffusion. The activation energy for self-diffusion in a (103) symmetric tilt boundary is much higher than in boundaries with other inclinations. We discuss the origin of the boundary plane density-diffusion coefficient correlation.