Phase constitution and fracture analysis of vacuum brazed joint of 50Mo-50Re refractory alloys

50Mo-50Re alloys thin sheet were successfully brazed with Ni-Cr-Si-B filler metal. δ-Ni(Mo, Re) and Г1-Ni(Mo, Si) solid solution, which ensured stable connection without obvious microdefects, were formed in the brazed seam region. Diffusion of Mo and Re elements, which dissolved from the substrates into the brazed seam region, caused solid solution strengthening of brazed seam. Metallographic analysis demonstrated the formation process of brazed seam with concentration gradient. Fracture morphology in the interface was a mixed intergranular and transgranular fracture, and the fracture located on interface of 50Mo-50Re refractory alloy and the central area of brazing seam.