Modelling of nanostructure evolution under irradiation in iron alloys

Neutron-irradiation induces in steels nanostructural changes, which are at the origin of the mechanical degradation that these materials experience during operation in NPP. Object Kinetic Monte Carlo (OKMC) modelling techniques have proved capable of simulating in a realistic and quantitatively reliable way the nanostructural effects of a whole irradiation process in metals and have therefore been used in the present work. The first part of this work aims at reproducing the nanostructural evolution under neutron irradiation at ~300°C of Fe-C alloys. The hitherto best choice parameters characterizing the mobility and stability of point-defect clusters in Fe-C alloys available has been developed. The second part of this work focuses on the study of the effect of Cr content on swelling in Fe-Cr alloys, always at ~300°C. We have used a physical description of the properties of point defects, based on a selection of the latest data from the literature and we have introduced the best set of parameters in the kinetic Monte Carlo model. Based on these simulations, the effect of carbon and chromium on the radiation defect evolution has been largely understood. Both models proved suitable to reproduce available experimental data in terms of defect cluster densities and size distribution.