Self-diffusion in aluminum at low temperatures

Abstract

Values of the self-diffusivity of pure aluminum in the temperature range 130∮ to 200° have been determined by measuring the rate of annealing of prismatic and faulted dislocation loops in thin foils of quenched 99.999 pct Al using a diffusion-controlled climb model due to Seidman and Balluffi modified to take into account elastic interaction between vacancies and dislocations. Changes in line energy of prismatic loops with orientation were evaluated and found to produce a maximum error in D of 17 pct. Other possible sources of error were evaluated. The results giveD = 0.19 ± 0.06 exp—(1.28 ± 0.04ev /KT sq cm per sec. A direct method of determining the activation energy for self-diffusion from prismatic loop annealing rates is presented which minimizes the effects of many sources of variation in individual climb rates.