Low-temperature thermally-activated deformation and irradiation softening in neutron-irradiated molybdenum

Abstract The effect of neutron irradiation on low-temperature deformation of Mo in two heat treatments, i.e. annealed and stress-relieved, was investigated. Specimens were irradiated at reactor coolant temperature (∼80 °C) to doses ranging from 7.2 × 10 −5 to 0.28 dpa in the High Flux Isotope Reactor. Tensile tests were carried out between −50 and 100 °C at strain rates of 1 × 10 −5 –1 × 10 −2  s −1 . Thermal activation analysis based on tensile data was performed to understand the low-temperature deformation mechanism. Irradiation softening and reduced dependence on test temperature and strain rate of the yield stress was observed in the annealed Mo after low-dose neutron irradiation (