To expand Ni-based superalloy and titanium alloy application fields, the preparation of Ni-based superalloy/titanium alloy composite joints is necessary. The GH4169/TC4 joint was prepared with Ti/Ni composite foils as interlayer by transient liquid phase (TLP) diffusion bonding. The microstructure, mechanical properties and formation mechanism of joint were investigated. The interfaces, fracture, composition and phases of as-prepared GH4169/TC4 joint were analyzed by scanning electronic microscopy (SEM), energy disperse spectroscopy (EDS) and X-ray diffraction (XRD), as well as the shear strength and microhardness of joints were tested by universal testing machine and microhardness tester, respectively. The results show that element interdiffusion and chemical reaction take place in the joining zone and multiple interlayer gradient structure, i.e. "GH4169/Ni(s,s)/TiNi3/Ti2Ni/Ti/Ti2Ni/Ni/TiNi+Ti2Ni/TC4" forms between GH4169 and TC4 under the process parameters of 960 degrees C, 5 MPa, 30 min. The joint is compact with continuous interfacial bonding without obvious defects except some pores and microcracks exist in the interface of "Ni/TiNi+Ti2Ni". The hardness of each part of the prepared joint is not uniform, among them, the residual Ti and Ni interlayers have lower hardness, which is beneficial to alleviate the internal stress, and the peak value appears in the GH4169 side as a result of the formation of Ni(s,s) and TiNi3. Combined with the shear test, fracture morphology and phase analysis, the shear strength of as-prepared GH4169/TC4 joint achieves 124.6 MPa and fracture occurs in the interface of "Ni/TiNi+Ti2Ni", which presents a brittle characteristic.
