Atomistic modeling of α’ precipitation in Fe-Cr alloys under charged particles and neutron irradiations: Effects of ballistic mixing and sink densities
Résumé
The alpha′ precipitation in Fe-Cr alloys under electron, neutron and ion irradiations is modelled by cluster dynamics and atomistic kinetic Monte Carlo simulations. The former method provides the evolution of the density of point defect sinks. This density is then introduced in the Monte Carlo which models the diffusion of point defects and atoms. By comparison with previous studies, this provides a better description of the evolution of point defect concentrations and therefore of the balance between two competing irradiation effects: the acceleration of diffusion and the ballistic mixing. The prediction of the model is in agreement with existing atomic-scale experiments already reported after electron, ion and neutron irradiations or obtained for the present study. Irradiation is found to accelerate the precipitation by orders of magnitude, except for the case of ion irradiation at high doses rates, where the simulations predict a ballistic dissolution of α′ precipitates. According to our model, this dissolution is mainly due to a high sink density, which reduces the concentrations of point defects and limits the acceleration of diffusion. This effect may be reinforced by carbon contamination, which reduces the mobility of point defects.