The Effect of Solute Atoms on Grain Boundary Migration: A Solute Pinning Approach

The effect of solute atoms on grain boundary migration has been modeled on the basis of the idea that solute atoms will locally perturb the collective rearrangements of solvent atoms associated with boundary migration. The consequence of such perturbations is cusping of the boundary and corresponding stress concentrations on the solute atoms which will promote thermal activation of these atoms out of the boundary. This thermal activation is considered to be the rate-controlling mechanism in boundary migration. It is demonstrated that the current statistical approach is capable of explaining, in phenomenological terms, the known effects of solute atoms on boundary migration. The experimental results of the effect of copper on boundary migration in aluminum, due to Gordon and Vandermeer, have been well accounted for.