Phase transformation diffusion bonding of titanium alloy with stainless steel

Phase transformation diffusion bonding between a titanium alloy (TA17) and an austenitic stainless steel (0Cr18Ni9Ti) has been carried out in vacuum. Relationships between the bonding parameters and the tensile strength of the joints were investigated, and the optimum bond parameters were obtained: maximum cyclic temperature = 890 °C, minimum cyclic temperature = 800 °C, number of cycles = 10, bonding pressure = 5 MPa and heating rate = 30 °C/s. The maximum tensile strength of the joint was 307 MPa. The reaction products and the interface structure of the joints were investigated by light optical and scanning electron microscopy, energy dispersive spectroscopy and X-ray diffraction. The study indicated the existence of σ phase, Fe2Ti, Fe–Ti intermetallic and β-Ti in the reaction zone. The presence of the brittle Fe–Ti intermetallic phase lowered both the strength and the ductility of the phase transformation diffusion-bonded joint significantly.