The influence of elastic strains on the recovery of cold-worked copper

Abstract

It has been found from measurements of electrical resistivity that the recovery of cold-worked copper is speeded up by an elastic strain. For the part of the recovery caused by diffusion and annihilation of vacancies or other point-defects formed during plastic deformation, this effect can be attributed to a change in the diffusion coefficient of the defects. The relation between the diffusion coefficient of vacancies and an elastic deformation is governed by the change of the activation energy of migration of a vacancy with the elastic deformation. The change of the activation energy depends linearly on the deformation. When the coordinate axes are chosen suitably with respect to the crystal axes, it can be shown that this relation is given approximately by −ΔQ = Aε xx + A 2 ε yy + A 4 ε zz The constant A is derived from experiment and is found to be 32 eV. From the relation between the diffusion coefficient of vacancies and the elastic deformation, we can calculate the effect of the elastic strain fields of an edge dislocation. At a distance of about 100 Å a considerable influence is still found. The effect of the presence of dislocations on the diffusion process which precedes the annihilation of vacancies formed during cold-working is discussed.