Abstract
It is shown that in very high-purity aluminum, , the rate of vacancy annealing depends on vacancy concentration and annealing temperature but is independent of the temperature 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 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 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.
In zone-refined aluminum, , of lesser purity the rate of vacancy annealing depends upon per se and falls off more rapidly with decreasing vacancy concentration than in . Two hypotheses for the impurity effects are considered, namely: (1) trapping of vacancies by impurity atoms and (2) inhibition of dislocation climb by adsorbed impurities.
- Received 12 March 1959
DOI:https://doi.org/10.1103/PhysRev.115.560
©1959 American Physical Society