Anomalous diffusion and solid-solution separation under the effect of vacancy sources. Stationary stage

For an ideal binary solid solution with a nanograined structure, a general solution of the quasi-stationary diffusion problem at a fixed supersaturation of the grain boundary with vacancies and at a directed flow of vacancies has been found. For the cases of strong and weak differences in the mobilities of the components, analytical expressions that describe concentration profiles have been obtained. An analysis of their spatial evolution depending on the initial concentration of one of the components and on the ratio of atomic mobilities has been performed. At a certain difference in the component mobilities and a sufficiently large supersaturation with vacancies near their sink, a near-boundary layer enriched with the lower-mobility component is shown to be formed.