Anomalous phase transformations in nanostructured materials during severe plastic deformation

Abstract

The nature of anomalous diffusion phase transformations that occur in nanostructured materials during severe plastic deformation is discussed. The theoretical approach proposed is based on the assumption that fluxes of nonequilibrium vacancies that appear upon dynamic relaxation of internal stresses near grain boundaries, predominantly at triple junctions, play a significant role in these processes. A variant of the Gurov method of nonequilibrium hole gas, which results in a generalization of the Cahn-Hillard theory of spinodal decomposition to the case of fluxes of nonequilibrium vacancies, is proposed. Conditions of anomalous alloy formation are analyzed within the framework of a model of regular solid solutions using the methods developed in solving continuum problems with singularities.