Effect of neutron irradiation on low temperature toughness of TiC-dispersed molybdenum alloys

The effect of neutron irradiation on the low temperature toughness of TiC-dispersed molybdenum alloys that were recently developed for fusion applications was studied. Miniaturized bend bar specimens, 1 by 1 by 20 mm, of both the alloys with TiC additions to 1.0 wt% and TZM were irradiated to 8 × 10 23 n/m 2 ( E n > 1 MeV) at controlled cyclic temperatures between 573 and 773 K in the JMTR and were tested by impact three-point bending. It was shown that under irradiation conditions the developed alloys exhibited much higher toughness than TZM and the toughness increased with increasing TiC content. In addition, the ductility of the alloy with 1.0 wt% TiC increased drastically by the irradiation, by about five times, regardless of the occurrence of significant irradiation hardening. This notable ductilization bX irradiation is the first found in materials and is discussed in connection with radiation enhanced precipitates.