Effect of bonding time on interfacial microstructure and shear strength of vacuum diffusion bonding super-Ni/NiCr laminated composite to Ti-6Al-4V joint without interlayer

Super-Ni/NiCr laminated composite was successfully joined with Ti-6Al-4V by vacuum diffusion bonding at 950 °C temperature. Results show that the bonding interface was composed of sequentially Ni3Ti, NiTi and NiTi2 layers. The interfacial phase constituents were similar although the joints were obtained with different bonding time. But the bonding time had a significant effect on the interfacial microstructure when the bonding time was prolonged from 30 min to 90 min. The morphology of NiTi2 layer transformed from serrate to straight and eutectoid products (Ni3Ti and NiTi2) were formed in NiTi layer whose width increased significantly. The maximum shear strength of joint is 69.2 MPa obtained at 60 min. Most joints fractured at the super-Ni/Ni3Ti interface. The shear strength of joint is mainly attributed to the plastic deformation and shifting of super-Ni crystals.