Simultaneous formation of interstitial-and vacancy-type loops during irradiation

During the irradiation of metals at temperatures above Stage III, dislocation loops are formed. Both interstitial-and vacancy-type loops are observed. Their simultaneous formation is possible because of a difference in their capture efficiency for interstitials which is due to non-linear elasticity effects on the strain fields of loops. This difference is only a necessary condition for the nucleation of vacancy-type loops. Other conditions, such as temperature, dose rate, and the average interstitial capture efficiency of the entire sink structure must also be met. These conditions are investigated, and it is found that vacancy loops can nucleate at low temperatures and when the capture efficiency of the entire sink structure exceeds a critical value. With continuing irradiation, both interstitial-and vacancy loops grow to large radii, and the capture efficiency drops below the critical value. At this point, further vacancy-loop nucleation is terminated