The Influence of the Initial Defect Concentration on the Annealing of Low‐Temperature Irradiated Metals

Abstract

Abstract Measurements are made of isochronal annealing in aluminium, copper, silver, and gold, after irradiation at 4.5 °K with various doses of fast neutrons. It is shown that the relative amount of recovery within annealing stage I is reduced, and annealing stage III is shifted to lower temperatures with increasing defect concentration. The first observation can be explained by the higher probability for annihilation of close Frenkel‐pairs, during the radiation‐annealing process, compared with the probability for recombination of more distant Frenkel‐pairs. The shift with concentration of annealing stage III and annealing stage I E for aluminium indicates the existence of freely‐migrating defects. For aluminium the existence of two freely‐moving interstitials is confirmed. In addition it is shown that the observed annealing behaviour of all the metals considered can be explained by this two‐interstitial model (previously proposed by Seeger and Sosin) taking into account the different defect arrangements produced by low‐temperature electron and neutron irradiation.