Vacuum diffusion bonding of textured WC-Co cemented carbide and aluminum

The surface of WC-Co hard metal was mechanically textured and then precoated using BNi2 brazing filler metal, then the WC-Co/Al joint was prepared by vacuum diffusion bonding. The results indicated that the microstructure of the interface is aluminum/Al₃Ni+Al₃Ni₂+Al₅Co₂/Co-Ni(s.s)/W-Co-Ni/WC-Co. With the increasing of the precoating temperature, the volume of layer of W-Co-Ni compound increased and the morphology of the interface of WC-Co/BNi2 transformed from flat to irregular. With the increasing of diffusion bonding temperature, the thickness of Al₃Ni+Al₃Ni₂+Al₅Co₂ layer increased. It was found that when the bonding parameters increased, the shear strength of the joints increased in the first stage and then decreased. The maximum shear strength of WC-Co/BNi2/Al joints was 51MPa, with a precoating temperature of 1 050 ℃, diffusion bonding temperature of 575 ℃ with holding time of 90 minutes, which largely exceeded the shear strength of the joints without surface texturing pretreatment.