Effect of heat treatment on microstructure evolution and mechanical properties of P/M Ni-based superalloy at diffusion bonding interface

Effect of the heat treatment on the microstructure evolution and mechanical properties of the a P/M Ni-based superalloy in the diffusion bonding interface was studied by the optical microscope (OM), scanning electron microscope (SEM), electron probe microanalysis (EPMA), and elevated temperature tensile test. The results show that Cr, Mo, Co, W, Al, and Ti elements diffuse from the alloy matrix to the interface, which leads to the appearance of the obvious bond-affected zone. Ni element diffuses from the electrodeposited coating to the matrix, and reacts with Al and Ti to form the coarse γ' phases. The coarse γ' phases are distributed as a cluster band in the interface. The width of the bond-affected zone and the cluster band are changed by the further diffusion of Cr, Mo, Co, W, Al, and Ti elements after the sub solution treatment and super solution treatment. The tensile test at 650 ℃ shows that the fracture location of diffusion bonding interface includes both the interface and the matrix. A large number of dimples and a small amount of dissociation surface in the fracture surface are found, showing a ductile-cleavage mixed fracture mode. The interfacial strength increases significantly, but the interfacial plasticity decreases after the sub solid solution and aging treatment. The interfacial strength decreases and the interfacial plasticity further decreases after the super solid solution and aging treatment.