Simulation of nanostructural evolution under irradiation in Fe-9%CrC alloys: An object kinetic Monte Carlo study of the effect of temperature and dose-rate

摘要

Highlights ? Our model suggests a decrease of defect cluster number density with irradiation temperature, and an increase of it with the applied neutron flux. Both trends are in agreement with post-irradiation experimental observations. ? Defect number densities and mean sizes control hardening in neutron-irradiated materials: however, a higher density of smaller SIA defects may contribute more to hardening than a lower amount of bigger loops. ? Above ～290 °C a significant reduction of the SIA cluster number density is predicted: faster defects are more likely to be absorbed at sinks. Abstract This work explores the effects of both temperature and dose-rate on the nanostructural evolution under irradiation of the Fe-9%Cr C alloy, model material for high-Cr ferritic/martensitic steels. Starting from an object kinetic Monte Carlo model validated at 563 K, we investigate here the accumulation of radiation damage as a function of temperature and dose-rate, attempting to highlight its connection with low-temperature radiation-induced hardening. The results show that the defect cluster mobility becomes high enough to partially counteract the material hardening process only above ～290 °C, while high fluxes are responsible for higher densities of defects, so that an increase of the hardening process with increasing dose-rates may be expected.