Phase-field modeling of void migration and growth kinetics in materials under irradiation and temperature field

A phase-field model is developed to investigate the migration of vacancies, interstitials, and voids during irradiation in a thermal gradient. Void growth kinetics during irradiation are also modeled. The model accounts for the generation of defects including vacancies and interstitials associated with the radiation damage, recombination of vacancies and interstitials, defect diffusion, and defect sinks. The effect of void size, vacancy concentration, vacancy generation rate, recombination rate, and temperature gradient on a single void migration and growth is parametrically studied. The results demonstrate that a temperature gradient causes void migration and defect fluxes, i.e., the Soret effect, which affects void stability and growth kinetics. It is found that (1) void migration mobility is independent of void size, which is in agreement with the theoretical prediction under the assumption of bulk diffusion controlled migration; (2) void migration mobility strongly depends on the temperature gradient and (3) the effect of defect concentration, generation rate, and recombination rate on void migration mobility is minor although they strongly influence void growth kinetics.