Effect of Sintering Process on Microstructure and Mechanical Properties of W-Re Alloy

W-5Re-0.5HfC alloys were prepared by powder metallurgy, and the effects of three sintering processes including hydrogen, vacuum, and vacuum-hydrogen sintering on the microstructure and room-temperature mechanical properties of the alloys were systematically investigated. The results indicate that vacuum-hydrogen sintered billets exhibited optimal comprehensive performance, with average grain size (32.6 μm) and density (17.75 g·cm-3) intermediate between those of hydrogen-sintered (49.2μm, 18.42 g·cm-3) and vacuum sintered (12.4μm, 16.6 g·cm-3) billets, along with optimal forging process adaptability. After high-temperature deformation treatment, the room-temperature tensile strength of the vacuum-hydrogen sintered specimens (1425.21MPa) was slightly lower than that of the hydrogen-sintered specimens (1513.20MPa), but their elongation significantly increased to 16.2%. Microstructural analysis revealed that the higher strength of the hydrogen-sintered samples was attributed to the predominant presence of nano-sized hafnium carbide (HfC) particles, which contributed to effective material strength through the dispersion strengthening mechanism. In contrast, the vacuum-hydrogen sintered specimens contained hafnium oxide (HfO?) particles tightly bonded to the matrix. These particles effectively refined the grains while coordinating dislocation motion, thereby markedly improving plastic deformation capability, and resulting in an optimal balance between strength and ductility.