Ion-irradiation hardening of Ti/Ta-added reduced activation ferritic-martensitic steel evaluated with a new nanopillar fabrication technique

Radiation-induced hardening of newly developed Ti/Ta-added reduced activation ferritic-martensitic (RAFM) steel is evaluated by combining self-ion irradiation and cross-sectional micropillar compression tests. 500-nm micropillars were fabricated on a cross-section polished surface using argon ion beam at locations of the ion-irradiated and unirradiated layers. The compressed micropillars showed that the deformation mode and flow behavior were changed because of ion irradiation. The radiation-induced increase in yield strength was evaluated by considering the specimen size effects manifested in the micropillar compression tests. The evaluated radiation hardening of the Ti/Ta-added RAFM steel at the dose of ∼2 dpa was found to be comparable to that of the reference RAFM steel with a composition similar to Eurofer97. The size and the number density of radiation-induced dislocation loops are analyzed, and the difference between the two RAFM steels is discussed.