A thermodynamic theory of coupling between point-defect diffusion and dislocation plasticity

We develop a unified, thermodynamically consistent model for irradiation creep, that combines dislocation glide and the stress-induced preferential absorption (SIPA) of point defects at dislocations. Central to the model is the premise that the dynamics of point defects such as interstitials and vacancies is controlled by the ordinary temperature, while the dynamics of extended defects, among which dislocations are of prime relevance, is controlled by an effective temperature that pertains to the configurational degrees of freedom which evolve on a much slower time scale than the kinetic-vibrational degrees of freedom and, as such, fall out of equilibrium with the latter. Results for thermal and irradiation creep in copper suggest that conventional SIPA mechanisms are inadequate to explain the very pronounced dependence of the irradiation creep rates on stress and temperature, necessitating nontrivial corrections to the SIPA dislocation climb rates. These results enable us to gain important insights into the stress and temperature dependencies of dislocation climb.