The evolution of self-diffusion concentration depth profiles into a bulk polycrystalline material, from a thin-film tracer source, was studied by using the lattice Monte Carlo method. The onset of the type-B kinetics regime from the type-A kinetics regime was investigated for a cubic grain model. The latter was expected to capture the three-dimensional nature of the problem better than would the usual grain boundary slab model. The solutions of Whipple & Le Claire (derived for the constant-source condition), Suzuoka (derived for the instantaneous-source condition), Bokstein et al. (derived for the constant-source condition) and Levine & MacCallum (derived for the constant-source condition) were tested. All of these solutions described well the tail region of the profiles for this model; provided that a simple empirical factor was introduced in the case of the first three solutions. The intermediate type-AB kinetics regime proposed, by Divinski & Larikov, to exist between the type-A and type-B kinetics regimes was also investigated but could not be located from analyses of the best-fit exponents. Forcing a fit to the tail regions showed that their analysis required further refinement before it could be applied to this model.

Analysis of Kinetics Regimes in Grain Boundary Self-Diffusion. I.V.Belova, G.E.Murch: Philosophical Magazine, 2009, 89[7], 665-75