Interfacial microstructure and mechanical properties of transient liquid phase bonded IN718/Ti-6Al-4V joints

Transient liquid phase (TLP) bonding of Ti-6Al-4V/IN718 dissimilar joint was investigated using Cu interlayer at 950 °C for 5–45 min. The microstructure of the bonding zone was studied by using optical and scanning electron microscopes, energy dispersive spectroscopy, and X-ray diffraction analysis. Shear and microhardness tests were also used to evaluate the mechanical properties of the TLP joints. The results indicated that α-Ti, Ti 2 Cu, and Ti 2 Ni phases were formed in the athermally solidified zone of the joints. A Widmanstätten structure consisting of eutectoid mixture of α-Ti and Ti 2 Cu was formed in the diffusion affected zone of Ti-6Al-4V side, and the formation of β(Nb) and NiTi eutectic and Cr 2 Ti, FeTi, Ni 3 Nb, Fe 5 Nb 3 , and Cu 0.035 Ni 0.565 Ti 0.4 intermetallic compounds was predicted in the diffusion affected zone of IN718 side. The hardness values decreased in different bonding zones with extending the bonding time, while an inverse trend was observed in the athermally solidified zone. The maximum shear strength of 367 MPa was obtained. The morphology of the fracture surfaces of shear samples was investigated.