The Effect of Neutron Irradiation on the Tensile Properties and Microstructure of Several Vanadium Alloys

Specimens of V-15Cr-5Ti, VANSTAR-7, and V-3Ti-1Si were encapsulated in molybdenum alloy tubes containing ⁷Li to prevent interstitial pickup and irradiated in the Fast Flux Test Facility (FFTF), using Materials Open Test Assembly (MOTA) experiments, to a damage level of 40 displacements per atom (dpa). The irradiation temperatures were 420, 520, and 600°C. For a better simulation of fusion reactor conditions, helium was preimplanted in some specimens using a modified version of the “tritium trick.” The V-15Cr-5Ti alloy was most susceptible to irradiation hardening and helium embrittlement, followed by VANSTAR-7, and V-3Ti-1Si. VANSTAR-7 exhibited a relatively high maximum void swelling of ∼6% at 520°C while V-15Cr-5Ti and V-3Ti-1Si had values of <0.3% at all three temperatures. The V-3Ti-1Si clearly outperformed the other two vanadium alloys in resisting the effects of neutron irradiation.