Effect of interlayer on interfacial microstructure and properties of Ni80Cr20/TC4 vacuum diffusion bonded joint

In this work, Ni80Cr20 alloy was bonded with TC4 alloy by vacuum diffusion bonding technology at 950 °C with various interlayers. The effect of interlayer on the interfacial microstructure and properties of joint was investigated. Results indicated that distribution of Ni and Cr elements appears the characteristic of complementary in the reaction layer of Ti(Ni, Cr)3 + CrSS in the case of without interlayer. When Cu foil as interlayer, the asymmetric diffusion of Ti and Cu atoms led to Kirkendall pores reducing the interfacial bonding strength of Ni80Cr20/TC4 joint. Cu + Ti composite interlayer promotes to form interfacial liquid at 950 °C during bonding. At 30 min and 60 min holding time, the microhardness peak value in the joint with Cu + Ti composite interlayer is much higher than the other two. The maximum value of shear strength was 72.4 MPa in the case of Cu + Ti as composite interlayer with 90 min.