Spinodal decomposition of an alloy with a strong concentration dependence of the mutual diffusion coefficient

It is shown that the kinetics of decomposition of an alloy with a strong concentration dependence of the mutual diffusion coefficient is qualitatively different from the widely known kinetics of spinodal decomposition, since it includes the formation of metastable (in the kinetic sense) precipitates of the intermediate composition. Concentration dependence of the mutual diffusion coefficient is particularly due to the difference in impurity diffusion coefficients, as well as component self-diffusion coefficients, and it increases as temperature decreases. The calculations use an expression for the flow of component atoms in the absence of the substance flow, obtained previously under the kinetic theory of vacancy diffusion (“hole gas method”).