Effect of displacement dose and irradiation temperature on tensile and fracture toughness properties of titanium alloys

At a low dose level of 0.001 dpa the Ti6Al4V (α + β) alloy showed softening and at higher doses an increase in hardening and lack of work hardening after irradiation at 60 °C. The (α + β) alloy seemed to suffer from plastic instability when irradiated to a dose level of 0.3 dpa at 60 °C. At elevated temperatures a substantial amount of hardening was observed in the (α + β) alloy when tested in the irradiated condition. Earlier studies have shown that the fracture toughness behaviour of the irradiated Ti5Al2.5Sn (α) and (α + β) alloys were quite similar at ambient temperatures. At elevated temperatures, fracture toughness of the irradiated (α + β) alloy decreased more than that of the (α) alloy when compared to the results obtained in the unirradiated condition. The large irradiation hardening and loss of fracture toughness in the (α + β) alloy appears to be related to radiation dose level, temperature and radiation-induced precipitation in the (α + β) alloy.