Interfacial microstructure and shear strength of TC4 alloy joints vacuum brazed with Ti–Zr–Ni–Cu filler metal

Ti–6Al–4V alloy was successfully vacuum brazed with a commercial Ti-37.5Zr–10Ni–15Cu (wt.%) filler metal. The effect of brazing temperature and time on the microstructure and shear strength of the brazed joints were investigated. When the brazing temperature was 905 °C for 10 min, the typical interfacial microstructure of the brazed joint were a single layer of α-Ti with a high concentration of Ti, α-Ti, (Ti, Zr)2(Cu, Ni) intermetallic compound and eutectoid microstructure. Increasing the brazing temperature and time are beneficial to eliminate the (Ti, Zr)2(Cu, Ni) intermetallic compound that degrades the properties in the brazed joint. The shear strength of the brazed joint increases first and then decreases with brazing temperature, and increases with the extended holding time. The maximum shear strength of the brazed joint is 635.77 MPa at a brazing temperature of 920 °C for 30 min due to the high content of columnar α-Ti. Extending the brazing time is obviously beneficial to increasing the strength. The microstructure and shear strength of the brazed joint are highly dependent on brazing temperature and time.