Growth kinetics of phases in solid-state diffusion couples

The growth of solid phases which are produced by diffusion in bilayers or multilayers of different chemical species is studied by an approach based on an effective diffusivity. In this approach one does not assume a priori any phase layers and interfaces. A numerical procedure to obtain the solutions of the diffusion differential equation is presented and applied to a fictitious example and to a real situation. Good agreement is obtained between the calculated values and the experimental data reported in the literature for the Co/Si system. In the absence of nucleation restrictions and reaction barriers, the model is applicable to any binary diffusion couple with a given initial composition profile, for bulk or thin film configurations.