Cluster dynamics study of damage accumulation in helium-implanted Fe–2.5at%Cr alloy

Abstract

Cluster dynamics (CD) study of damage accumulation has been performed for helium-implanted Fe–2.5 at%Cr alloy with the flux of 7 × 10−6 dpa/s at the temperature of 343 K. Findings confirm the non-monotonic dose dependence of the vacancy clusters mean size for irradiation doses from 0.15 to 0.74 dpa, observed in the positron annihilation spectroscopy experiment. The effect of the chromium and carbon atoms on the formation and kinetics of point defects clusters has been taken into account. The ratio of vacancies formed to cluster to the total number of surveillance vacancies at the end of the cascade stage (irradiation parameter fvcl) and migration energy of vacancies in bcc iron (material parameter Emv) have been varied to provide the best fit of CD simulation results to positron annihilation spectroscopy data on the positron lifetime in defects. The calibrated CD model has been used to study the effect of the presence of vacancy clusters in the non-irradiated state Fe–2.5at%Cr alloy on the evolution of point defect clusters in this material due to helium implantation.