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.