Influence of Rhenium Content on Vacancy-Type Defect Distribution in Mo-Re Alloys Under Room-Temperature Irradiation

Mo-Re alloys serve as critical structural components for high-temperature nuclear reactors, and their irradiation degradation is closely related to the evolution of vacancy-type defects. In this study, heavy-ion and He-ion irradiations were performed under RT to introduce an average displacement damage of 3.5 dpa within the 1 μm-thick surface layer of Mo-Re alloys with Re content up to 47 wt.%. PALS, SPB-DBS and CDB techniques were employed to characterize the size, concentration, depth distribution and local chemical environment of irradiation-induced vacancy-type defects. The results demonstrate that the longer lifetime component of irradiated Mo-Re alloys ranged from 262 to 280 ps, corresponding to medium-sized vacancy clusters. The S parameter of all specimens increased significantly from approximately 0.42 to 0.50, with negligible differences (<0.01) among various Mo-Re alloys. No distinct characteristic peak of Re was observed near 17 × 10^-3 m₀c at the vacancy sites, which was inconsistent with simulation predictions. Mo-Re alloys exhibit similar vacancy-type defect features to pure Mo, implying weak interactions between Re solute atoms and vacancy-type defects under RT irradiation.