Improvement in post-irradiation ductility of neutron irradiated V–Ti–Cr–Si–Al–Y alloy and the role of interstitial impurities

An attempt to maintain the uniform elongation (UE) of vanadium alloys after irradiation is described. Neutron irradiation was carried out at Advanced Test Reactor (ATR) and at Experimental Breeder Reactor II (EBR-II) to the fluence of 11 dpa. The UE was maintained about 6% after irradiation at 388°C. The UE became negligible after irradiation below 300°C for the alloy annealed at 1000°C and 1100°C. The specimens annealed at 900°C and 700°C still showed relatively large UE after such low-temperature irradiation. Comparing with the results in literature, it is proposed that oxygen concentration should be kept below 200 ppm to maintain the UE after irradiation below 400°C. The control of interstitial impurities, especially oxygen in solution, was important to maintain the UE of the alloy.