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-Ill annealing. Both methods give 0.85=1=0.02 eV for the activation energy in high-purity irradiated specimens. The activation energies for quenched and for quench-plus-irradiated specimens of comparable purity are found to be 0.85=1=0.03 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-Ill annealing for the irradiated, quench-plus-irradiated, and quenched specimens. Various models are discussed to explain stage-Ill 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.

Stage Iii Annealing of Electron Irradiated Silver.

“…One possibility is that there is an impurity effect which tends to lower the vacancy migration energy. In going from electron irradiated gold having residual resistivity 6 .3xlo-9 0-cm to a residual resistivity of .lx10-9 0-cm, the 4) activation energy was seen to rise by ..04 ev. Using a value -4 of 2x10 0-cm as the resistivity of 100% impurities, this I, indicates that an impurity background of 10-6, which is less The precipitate was assumed to be 40 X on a side for a defect concentration of 1.5x10-5, which is in reasonable agreement with microscope observation.…”

On the point-defect annealing mechanism for stage III recovery in irradiated or quenched tungsten

“…We emphasize, Qnce again, that the temperature range of Stage III in quenched w is often different from that of irradiated W because of the larger number of jumps made by a vacancy before it is annihilated in quenched W; (23,27,(36)(37)(38)(39)) also see Fig. 12 in reference (22) and Fig.…”

Resistivity recovery of neutron-irradiated and cold-worked thorium

“…Au (25,26), and Pt (27). In all these metals a single well defined peak has been observed in stage III, which is, however, shifted to lower temperatures with increasing The origin of stage III has been a subject of contro versy for some time.…”