Diffusion bonding of Ti-6Al-4V (TC4) to oxygen free copper (OFC) at low temperature was carried out using silver foil as interlayer. Results show that the interlay can prevent the formation of brittle Ti-Cu compounds and improve the interfacial microstructure and bonding strength of the TC4/OFC joint. Moreover, adding the silver interlayer greatly lowers the bonding temperature. The composition of the joint from the TC4 side to the OFC side is TC4 substrate, AgTi compound, Ag interlayer, Ag-Cu solid solution and OFC substrate. The tensile strength of the joint bonded at 700 °C for 1 h under 10 MPa bonding pressure has an excellent value of 150 MPa, higher than those previously reported in literatures. Fracture failure takes place in the Ag/OFC interface and ductile fracture can be observed on the fracture surface. It is suggested that the ductile properties of the AgTi compounds are superior to that of Ag-Cu solid solution in this joint.
