SWELLING OF NEUTRON-IRRADIATED VANADIUM ALLOYS

The swelling of unalloyed vanadium and vanadium alloys containing Cr, Ti, Si, Fe, Zr, W, Mo, and Ni additions was determined after neutron irradiation at 420 and 600-degrees-C to 17-84 dpa in the FFTF-MOTA reactor facility. The swelling of these materials was obtained from a determination of the immersion density of the unirradiated and irradiated materials. The swelling of V is substantially increased by the addition of Cr, and significantly reduced by the addition of Ti. The swelling of V-Cr-Ti alloys is strongly dependent on Ti concentration for Ti concentrations < 3%. For resistance to irradiation-induced swelling, the Ti concentration in a V-Cr-Ti alloy that is to be used as a structural material in a magnetic fusion reactor should be greater than 3%. For these ranges of Ti concentration in a V-Cr-Ti alloy, Cr concentrations of < 15% have minimal effect on the swelling of the alloy. The Vanstar-7 alloy exhibits high (7-10%) swelling on irradiation at 600-degrees-C to 77 dpa. Swelling of V-7.2Cr-14.5Ti, V-13.5Cr-5.2Ti, V-9.2Cr-4.9Ti, V-3.1Ti-(0.3-0.5)Si, and V-17.7Ti on neutron irradiation at 600-degrees-C to 87 dpa is (in % per dpa) 0.10, 0.03, 0.03, 0.01, and 0.01, respectively.