Radiation embrittlement of Mo-Re welds under low-temperature irradiation in the SM reactor

The results of irradiation influence at 120-160 deg C up to 3.6-6.0 mult 10 exp 21 n/cm exp 2 (E > 0.1 MeV) in the SM reactor on mechanical properties and microstructure of the electron-beam welds of Mo-Re alloys with a content of 15%, 20%, 30%, and 41%) Re are presented in the paper. Severe radiation embrittlement of these materials due to formation of dislocation loops is observed. The welds of Mo-Re alloys with the higher Re content are comparatively less susceptible to the radiation embrittlement. The density of dislocation loops is reduced and the fracture type is changed from intergranular to transgranular with an increase of Re content in the alloys. There is no formation of dislocation loops at all in the weld-fusion zone of Mo-41Re alloy after the initial annealing at 1400 deg C for 1 h. No radiation-induced formation of the second phases is detected in the investigated Mo-Re alloys.