Diffusion characteristics of vacancies and atoms in Fe–Cr alloys with body-centered cubic (bcc) and face-centered cubic (fcc) lattices are studied using a modified molecular statics method. In contrast to the standard molecular statics method, in this model the main computational cell is surrounded by atoms embedded in an elastic continuum. The positions of atoms in the main computational cell are determined using a gradient descent algorithm. The displacements of atoms located in the elastic continuum are obtained using solutions of the equations of elasticity theory for defects with spherical symmetry. The atomic structure in the main computational cell and the displacements of atoms in the elastic continuum are determined self-consistently through several iterations. For modeling, many-body potentials of the embedded atom method (EAM) type fitted for Fe–Cr alloys with body-centered cubic (bcc) and face-centered cubic (fcc) lattices at various concentrations are used. Based on the calculated atomic structure, dependences of the diffusion characteristics of vacancies and atoms on composition are obtained. An increase in chromium content in the body-centered cubic structure leads to a decrease in the energy barrier for Fe atoms, while in the face-centered cubic structure it leads to an increase. Activation energies for both lattice types increase with increasing chromium content, especially for Cr atoms. Dependences of vacancy formation energies, energy barrier heights, and activation energies are obtained; these are used to determine the effect of composition on vacancy concentration, correlation factors, and diffusion coefficients. The results can be used for modeling interdiffusion processes, phase growth kinetics, and decomposition of solid solutions.
Sergeev et al. (Mon,) studied this question.