Microstructural evolution and mechanical properties of vacuum brazed Ti₂AlNb alloy and Ti60 alloy with Cu75 P t filler metal

Cu75 P t filler metal was firstly used to vacuum braze Ti₂AlNb alloy to Ti60 alloy and the sound joints were obtained in this work. The solidus temperature of Cu75 P t filler was 1127 °C. The typical interfacial microstructure of Ti60/Cu75 P t/Ti₂AlNb joint brazed at 1180 °C for 10 min was Ti60 substrate/β-Ti + α-Ti + Ti₃Pt/Ti₃Pt/B2 + α₂/Ti₂AlNb substrate. The effects of brazing temperature on the interfacial microstructure and mechanical properties of the Ti60/Cu75 P t/Ti₂AlNb brazed joints were investigated. The increasing of brazing temperature accelerated the diffusion of liquid filler into substrate, resulted in the decrease of Ti₃Pt brittle phase and the grain growth of substrates. The shear strength of the joints brazed at 1200 °C for 10 min reached the maximum of 93 MPa. The fracture surface of the joint was characterized as Ti₃Pt brittle phase and it cracked in β-Ti when brazing temperature reached 1210 °C.