The influence of fast neutron irradiation and irradiation temperature on the tensile properties of wrought LCAC and TZM molybdenum

The effects of irradiation temperature on embrittlement are evaluated by the irradiation of wrought low carbon arc cast (LCAC) and TZM molybdenum in the High Flux Isotope Reactor at 294-1100 °C to neutron doses between 0.6 and 13.1 dpa Mo. Irradiation at 300 °C is shown to result in elevation of the ductile to brittle transition temperature (DBTT) from a pre-irradiated value of -100 to -50 °C to a post-irradiated value of 800 °C for both alloys with an increase in fracture stress. Irradiation at 560 °C also resulted in an increase in fracture stress, but the post-irradiated DBTT for LCAC (300 °C) was much lower than TZM (700 °C). Irradiation of both LCAC and TZM between 935 °C and 1100 °C resulted in little radiation hardening and a -50 °C DBTT for both alloys. The finer grain size and absence of coarse carbide particles may explain the slightly improved embrittlement resistance of LCAC compared to TZM for 600 °C irradiations.