Interfacial microstructure and mechanical property of Ti60 and TC4 joint brazed with Cu75Pt filler metal

The Ti60 titanium alloy was successfully vacuum brazed with TC4 titanium alloy by using Cu75Pt filler metal. The microstructure of brazed joints was analyzed by scanning electron microscope (SEM), energy dispersive spectrometer (EDS) and X-ray diffraction (XRD). The results showed that the typical microstructure of Ti60/Cu75Pt/TC4 joint was Ti60/Ti₂Cu + α-Ti/Ti₂Cu/Ti₂Cu + Ti₃Pt/Ti₂Cu/Ti₂Cu + α-Ti/TC4. The effect of different brazing temperatures on the interfacial microstructure and mechanical properties of joints was studied. The results revealed that with the increasing of brazing temperature, the thicknesses of diffusion layers were increased gradually. However, the Ti₂Cu, Ti₃Pt and the width of brazing seams were decreased. The shear strength of the joint increased first and then decreased with the increase of brazing temperature. The maximum shear strength of 130.9 MPa was obtained at the brazing temperature of 970 ℃ for 10min. The fracture analysis of the joint showed that the fracture mode is brittle fracture, which occurred in the center of brazing seam.