Study of the mechanisms of deformation in ultrafine-grained and coarse-grained copper at different temperatures by the methods of kinetic simulation

Abstract

Kinetic-simulation methods were used to investigate the mechanisms of deformation of ultrafine-grained copper produced by equal-channel angular pressing. The study was based on the modernized Estrin-Toth dislocation model, which takes into account, besides the slip of dislocations, the possibility of their non-conservative motion, which is connected with the presence of a large quantity of vacancies in the materials subjected to severe plastic deformation. Furthermore, apart from an analysis of the evolution of the total dislocation density, the evolution of the forest dislocations in the walls of cells (grains) was taken into account, which made it possible to calculate the change in the misorientation angles between the adjacent cells (grains) in the course of plastic deformation. As the experimental data, the true tensile stress-strain curves of ultrafine-grained Cu obtained at temperatures of 77 and 298 K were used. To investigate the effect of grain size on the kinetics of plastic deformation at the above temperatures, analogous calculations were carried out for the case of coarse-grained Cu.