The influence of impurity atoms on the annealing kinetics of neutron irradiated copper

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Abstract
Spectroscopically pure copper and a series of dilute binary allsoys of copper, containing between 0.02 and 1 atomic % of silver, cadmium and beryllium respectively, have been neutron irradiated to doses of between about 1 and 5 × 1017 n.v.t. at −196°c. A series of isochronal anneals up to + 150°c were performed and the recovery of the radiation damage has been observed by measuring changes of the electrical resistance in liquid helium. Three principal annealing peaks at approximately −140°c, −60°c and 0°c which are superposed upon a continuous annealing up to 0°c have been observed for all the specimens. However, the heights and exact temperatures of the peaks vary with impurity concentration and neutron dose. From a study of these variations, together with some experimental results which have been obtained on pure copper quenched from high temperatures, it is suggested that the first two peaks are due to the migration of interstitials from traps and the third to migration of free vacancies. The nature of these traps is discussed in some detail. It is also shown that the details of the annealing processes in beryllium-copper are different to those of the alloys of silver and cadmium.