Stage III annealing in gold after electron irradiation

Abstract

Gold specimens of nominal 99.9999% purity were irradiated with 3 MeV electrons near liquid nitrogen temperature. The damage production rate is found to depend on the purity of the specimen giving a lower value for the high purity specimens. It is also found that the production rate is reduced remarkably by quenching the specimen before irradiation. For high purity gold, a single large annealing peak is observed in Stage III. The slope change method and Primak analysis are employed to obtain the activation energy of Stage III annealing. Both methods give 0.85 ± 0.02 eV for the activation energy in high purity irradiated specimens. The activation energies for quenched, and quench-plus-irradiated specimens of comparable purity are found to be 0.85 + 0.03 eV and 0.86 + 0.02 eV respectively, agreeing with the value for the irradiated specimens within the experimental error. Somewhat lower values are obtained for specimens of lower purity. Second order kinetics are obeyed in the main part of the Stage III annealing for the irradiated, quench-pius-irradiated and quenched specimens. Various models are discussed to explain Stage III annealing. It is concluded that vacancy migration in Stage III with interstitial clusters acting as sinks can account for the observed results most satisfactorily in the case of gold.