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 deg. C to neutron doses between 0.6 and 13.1 dpa Mo. Irradiation at 300 deg. C is shown to result in elevation of the ductile to brittle transition temperature (DBTT) from a pre-irradiated value of -100 to -50 deg. C to a post-irradiated value of 800 deg. C for both alloys with an increase in fracture stress. Irradiation at 560 deg. C also resulted in an increase in fracture stress, but the post-irradiated DBTT for LCAC (300 deg. C) was much lower than TZM (700 deg. C). Irradiation of both LCAC and TZM between 935 deg. C and 1100 deg. C resulted in little radiation hardening and a -50 deg. 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 deg. C irradiations