Study on inhibition of interfacial compounds and improvement of joint properties by low temperature and high-pressure process in diffusion bonding of Ti/Cu

The vacuum diffusion bonding of Ti/Cu under low temperature and high pressure was prepared to explore a suitable process to inhibit the formation of Ti–Cu intermetallic compounds and thus effectively improve the strength of Ti/Cu joints. The conventional diffusion bonding of Ti/Cu joint was also compared and analyzed. The diffusion process, especially the bonding temperature, significantly influences the morphology of the joint interface. At a lower diffusion temperature (550–580 °C) and a larger bonding pressure (30∼40 MPa), the effective bonding of Ti/Cu was realized. Low temperature inhibited the nucleation and growth of intermetallic compounds, and the types and thicknesses of intermetallic compounds at the interface decreased significantly. The interface of the Ti/Cu joint prepared at 550°C- 40 MPa formed an amorphous transition layer with a width of approximately 10 nm, rather than a brittle intermetallic compound layer. The grain size of the transition layer was mainly concentrated in the range of 0.25–1.05 μm. The hardness distribution of the sample did not show an obvious increase. The shear strength of the Ti/Cu joint at 580°C-30MPa reached 181 MPa.