Interfacial microstructure and mechanical properties of TC4/Ti60 brazed joints

TC4 alloy and Ti60 alloy were brazed using TiZrNiCu amorphous filler alloy. Effects of the brazing process parameters on the interfacial microstructure and mechanical properties of the joints were studied. The interfacial microstructure and possible phases of the joints, as well as the fracture form of fractures, were detected by scanning electron microscope(SEM), energy dispersive spectrometer(EDS) and X-ray diffraction(XRD). The results showed that the typical interfacial microstructure of TC4/Ti60 joint was TC4/α-Ti+β-Ti+(Ti,Zr)2(Ni,Cu)/Ti60. With increased brazing temperature or prolonged holding time, lamellar α+β microstructure filled the whole brazing seam gradually and (Ti,Zr)2(Ni,Cu) phase was distributed more evenly. With increasing of brazing temperature or holding time, tensile strength of the joints was first increased and then decreased. The highest tensile strength, 535.3 MPa, was obtained when the joints were brazed at 990 ℃ for 10 min. Fracture analysis indicated that the joints were fractured at brazing seam, which performed as brittle fracture.