Irradiation Hardening Behavior of He-Irradiated V-Cr-Ti Alloys with Low Ti Addition

A set of V-(4-8)Cr-(0-4)Ti alloys was fabricated to survey an optimum composition to reduce the radioactivity of V-Cr-Ti alloys. These alloys were subjected to nano-indenter tests before and after 2-MeV He-ion irradiation at 500 degrees C and 700 degrees C with 0.5 dpa at peak damage to investigate the effect of Cr and Ti addition and gas impurities for irradiation hardening behavior in V-Cr-Ti alloys. Cr and Ti addition to V-Cr-Ti alloys for solid-solution hardening remains small in the unirradiated V-(4-8)Cr-(0-4)Ti alloys. Irradiation hardening occurred for all V-Cr-Ti alloys. The V-4Cr-1Ti alloy shows the highest irradiation hardening among all V-Cr-Ti alloys and the gas impurity was enhanced to increase the irradiation hardening. These results may arise from the formation of Ti(CON) precipitate that was produced by He-ion irradiation. Irradiation hardening of V-Cr-1Ti did not depend significantly on Cr addition. Consequently, for irradiation hardening and void-swelling suppression, the optimum composition of V-Cr-Ti alloys for structural materials of fusion reactor engineering is proposed to be a highly purified V-(6-8)Cr-2Ti alloy.