Microstructural characterization of Eurofer-97 and Eurofer-ODS steels before and after multi-beam ion irradiations at JANNUS Saclay facility

RAFM steels such as Eurofer-97 and Eurofer-ODS are potential structural materials for future fusion reactors. In order to study their resistance to the high energy neutrons they will be subjected to in this context, we have irradiated these materials in single-, dual- and triple-beam mode to 26 dpa at 400 °C. In single-beam mode (Fe ions only), both materials resist swelling but dislocation loops form. For dual- (Fe and He ions) and triple-beam (Fe, He and H) modes, the same dislocation loop microstructure is observed as for the single-beam mode, but small cavities form, aided by the presence of gases. Despite the formation of cavities, swelling is very low for the present conditions. The influence of ODS particles on swelling is briefly discussed. - Highlights: • Eurofer-97 and Eurofer-ODS are multi-beam irradiated with Fe, He and H ions. • Dislocation loops form after single-beam Fe ion irradiation to 26 dpa at 400 °C. • Co-implantation of helium leads to formation of cavities at 26 dpa/400 °C.