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

The influence of neutron irradiation in FFTF on the microstructural and microchemical development of Mo–41Re at 470–730°C

“…There were no precipitates or voids under these conditions. Chakin and coworkers [13] also investigated Mo-Re alloys at 15%, 20%, 30%, and 41% Re irradiated in the SM-2 reactor to relatively low neutron exposures at temperatures of 120-160°C. They also did not observe any precipitates, but only dislocation loops.…”

Rhenium Effect in Irradiated Mo-Re Alloys and Welds

“…A hardness increment after irradiation at 673 K is approximately twice that which occurs after irradiation at 1073 K for polycrystalline molybdenum and approximately half as much again for single crystals [19]. In contrast to low-alloyed materials, Mo-Re alloys exhibit a pronounced hardening after irradiation at both low and high temperatures [14,15]. This is seen from the results of microhardness measurement (Fig.…”

“…In case of welds, more subcritical cracks, such as micropores or other flaws, are accumulated in coarse grains of WM compared to BM or HAZ. Therefore, the fracture surface will preferably be located within the weld metal, as is observed in the experiment [14].…”

“…5a,b). With increasing rhenium content from 16% to 41% in LT-irradiated Mo-Re alloys, the density of dislocation loops with an average size of 7.5~10 nm is reduced by 4~6 times from 4.5×10 21 to 2.6×10 22 m -3 [14]. The space distribution of dislocation loops is extremely irregular in the BM of Mo-41Re weld, while these defects are not practically observed in the WM zone.…”

“…Neutron irradiation causes strong hardening of the matrix and simultaneously reduces the plasticity of Mo-based alloys. Dependence of the radiation effects on the metallurgical factors, such as fabrication process, alloy composition, heat treatment, irradiation conditions, has been intensively studied in both low-alloy Mo and Mo-Re alloys [8][9][10][11][12][13][14][15]. Despite evident progress being achieved in the understanding of radiation-induced embrittlement, prospects for practical usage of Mo base alloys in fusion reactor elements are, however, still under discussion.…”