Recovery of Resistivity of Pure and Alloyed Aluminum in Stages II and III after 2-MeV Electron Irradiation

Abstract

Samples of pure aluminum and aluminum alloyed with 0.3 at.% Zn, Cu, and Ge were irradiated by 2-MeV electrons to several widely differing doses and at a variety of temperatures. Isochronal annealing studies were performed with 30-min anneals spaced 5° apart from 60°K to the conclusion of stage III. In one experiment a pure aluminum and a zinc-alloy sample were exposed to air when at a temperature of 300°C prior to irradiation. The presence of the additional air impurities was found to impede the motion of the defect migrating in stage III. Impurity effects dominate the recovery through the stage-II region and extend into stage III, although the possibility of an intrinsic process near 73°K exists. From the results of this work, the stage-III recovery in pure aluminum can be explained in terms of a model where single vacancies migrate to clusters of interstitials that were formed during the preceding stages of annealing.