Such growth was studied by using an approach that was based upon an effective diffusivity. In this method, the existence of phase layers or interfaces was not assumed  a priori. A numerical method was used to obtain solutions to the differential equation for diffusion. Good agreement was found between calculated values and experimental data. In the absence of nucleation and reaction barriers, the model was applicable to any binary diffusion couple (bulk or thin film) with a given initial composition profile.

V.H.Garcia, C.Scherer, P.M.Mors: Physica Status Solidi A, 1995, 152[2], 385-92