Recovery of electrical resistivity of high-purity iron irradiated with 30 MeV electrons at 77 K

The characteristics of radiation-induced defects in high-purity iron subject to 30 MeV electron irradiation at 77 K have been studied using electrical resistivity recovery measurements. For lowest electron dose, the stage II consists of two substages at 165 K and at 180 K. With increasing dose, the 165 K stage remains unshifted whereas the 180 K stage shifts to lower temperatures. These substages are attributed to the free migration of di-interstitials within and outside the displacement cascade, respectively. For higher electron doses, a slight substage (180–190 K) may be associated with the correlated annihilation of vacancies observed after fast neutron irradiation. Furthermore, another marked stage (210–240 K) with the dose dependence of peak temperature shift is ascribed to the monovacancy migration. From these results, it has been verified that the radiation damage produced by 30 MeV electrons comprises two types of defect structures; one associated with displacement cascades and the other one associated with simple displacement processes.