The increase in electrical resistivity which occurred during 1.85MeV electron irradiation, at temperatures below stage-III recovery, was monitored. The data were analyzed by using rate equations, and this yielded the variations in the concentrations of interstitials, vacancies and interstitial agglomerates as a function of irradiation time and temperature. It was found that the number of replacement collision sequences of dynamic crowdions, before they changed into stable interstitials, was equal to about 40000 in well-annealed pure Cu, in commercial-grade Cu, and in pure Au. This number decreased upon adding Be, and was equal to about 15 in Cu which was doped with 763ppmBe. The rate of spontaneous annihilation of vacancies with dynamic crowdions during irradiation depended upon the number of replacement collision sequences. Therefore, the production rates of vacancies and interstitials considerably decreased, in the pure metals, with increasing irradiation time. On the other hand, the production rate of dynamic crowdions did not decrease with increasing irradiation time (increasing concentrations of vacancies and interstitials) and was equal to the initial production rate of interstitials. The initial production rate of point defects was the production rate as determined for a zero defect concentration. Recovery in stages III and IV was investigated in Cu which contained 763ppmBe. After small irradiation doses, recovery stage-III was mainly observed. After large irradiation doses, recovery stage-IV was mainly observed. Activation energies of 0.72 and 1.07eV, respectively, were determined for these 2 recovery stages and were attributed to the activation energies for the migration of interstitials and vacancies, respectively. These values were only very slightly higher than those which had been determined for pure Cu. It was concluded that the migration activation energies of Cu and Be in the dumb-bell configuration were very similar to that for self-interstitials in pure Cu. The binding energy of Be to vacancies was therefore expected to be very small.

Dynamic Crowdions, Interstitials and Vacancies in Copper. H.Gilhaus, W.Schule: Radiation Effects and Defects in Solids, 1996, 138[1-2], 29-38