Calculation and Simulation of Interdiffusion Coefficients and Ordering Kinetics in Binary Alloys.

Abstract

AbstractRate equations for thermally activated atomic exchange were used to calculate chemical diffusion coefficients for an initially disordered simple-cubic lattice and for a body-centered lattice with equilibrium long-range order. The results show that the chemical enhancement as a function of the enthalpy of mixing saturates, in contrast with results of conventional mean-field theories. Simulations in a disordered alloy agree with the calculations. The existence of longrange order is shown to increase the apparent activation energy for diffusion. The present theory is also shown to provide a simple method of calculating ordering kinetics and equilibrium longrange order, and good agreement with previous experiments and simulations is achieved.