A thermostatistical theory of low and high temperature deformation in metals

Abstract

Abstract A new theory for describing plastic deformation in metals is presented. The approach focuses on obtaining an expression for the dislocation recovery term in terms of the energy barrier for dislocation annihilation, 〈Δ G 〉. This term is obtained from the contributions of dislocation formation and migration, the statistical entropy inherent to the annihilation process, and the chemical work due to the presence of vacancies. It is shown that at high temperatures, vacancy migration features strongly in dislocation recovery via a climb-assisted process. Employing only input parameters reported in the literature, the theory is able to reproduce experimental stress–strain relationships at temperatures ranging from cryogenic conditions to near-melting temperatures for Cu, Al, Ni and Ag at a variety of strain rates. It is demonstrated that low temperature cross-slip can operate at higher temperatures by increasing the strain rate, and that high temperature dislocation climb can feature at low temperatures by reducing the vacancy migration energy.