Kinetics of Vacancy Motion in High-Purity Aluminum

Abstract

It is shown that in very high-purity aluminum, ${\mathrm{Al}}_{\mathrm{II}}$, the rate of vacancy annealing depends on vacancy concentration and annealing temperature but is independent of the temperature $T_i$ of vacancy injection per se. The rate can be described as the sum of first and second order components. The first order component becomes most prominent at a monovacancy concentration estimated to be ${10}^{-6\mathrm{}}$ atom fraction. It is shown that the results are consistent with the Koehler-Seitz-Bauerle dissociative mechanism. The activation energy for diffusion of monovacancies in ${\mathrm{Al}}_{\mathrm{II}}$ is found to be 0.65±0.06 ev. This, combined with earlier results on the formation energy of vacancies, gives 1.44±0.11 ev for the activation energy for self-diffusion in aluminum by a monovacancy mechanism.