It was recalled that knowledge of the limits of the principal Harrison kinetics regimes (A, B, C) for grain boundary diffusion was very important for the correct analysis of depth profiles in a tracer diffusion experiment. These regimes for self-diffusion were extensively studied in the past by making use of the phenomenological lattice Monte Carlo method with the result that the limits were now well established. However, the relationship of these self-diffusion limits to the corresponding ones for solute diffusion in the presence of solute segregation to the grain boundaries remains unclear. In the present study, the influence of solute segregation on the limits was investigated with the lattice Monte Carlo method for the well-known parallel grain boundary slab model by showing the equivalence of two diffusion models. It was shown which diffusion parameters were useful for identifying the limits of the Harrison kinetics regimes for solute grain boundary diffusion. It was also shown how the measured segregation factor from the diffusion experiment in the Harrison Type-B kinetics regime may differ from the global segregation factor.

The Harrison Diffusion Kinetics Regimes in Solute Grain Boundary Diffusion. I.V.Belova, T.Fiedler, N.Kulkarni, G.E.Murch: Philosophical Magazine, 2012, 92[14], 1748-63