Interface migration and the Kirkendall effect in diffusion-driven phase transformations

An analysis is presented for the mass and vacancy fluxes within the reacting phases and at the interface for a diffusion-driven phase transformation between disordered binary solid solutions. As decided by the intrinsic diffusion coefficients and the initial and interface concentrations for each phase, vacancies must either be created or annihilated in the bulk phases but also at their interface. A general analysis is formulated for the growth or recession of a phase in terms of the Kirkendall reference frame and this result is compared to the analysis based on the reference frame centered on the number of moles. Specific example calculations demonstrate the various possiblities for vacancy creation/annihilation and for the growth/recession of phases. The growth rate expressed in the Kirkendall reference frame can be found by taking into account the associated vacancy exchanges for the interface reaction.