Interfacial microstructure and mechanical property of Ti60/Ti2AlNb alloy joints brazed with TiZrNiCu amorphous filler metal

The Ti60 alloy was successfully vacuum-brazed with Ti₂AlNb alloy by using TiZrNiCu amorphous filler metal. SEM, EDS, and other methods were used to analyze the interfacial microstructure of the brazed joint. The influence of brazing temperature on the interfacial microstructure and mechanical properties of the joint was studied. The results show that the typical interfacial microstructure of the brazed joint is Ti60/α + β/(Ti,Zr)₂(Ni,Cu)/α + β/B2/β/Ti₂AlNb. As the brazing temperature increases, the content of (Ti,Zr)₂(Ni,Cu) compound decreases, and they distribute more evenly. A lower brazing temperature causes the thick brittle compound layer, making it prone to microcracks and becoming a weak link in the joint. Besides, the large-scale lamellar α + β microstructure is formed at the base metal of Ti60 when the brazing temperature is too high. With the increase in brazing temperature, the shear strength of the joint first increases and then decreases. The maximum average shear strength of 283.9 MPa is obtained at the brazing temperature of 980 °C for 10 min. Fracture analysis indicates that all fractures occur at the brazed joints and are brittle.