Ti-Nb-Cu Stress Buffer Layer for TiC Cermet/304 Stainless Steel Diffusion Bonding

Vacuum diffusion bonding of TiC cermet/304 stainless steel (304SS) was conducted and Ti-Nb-Cu multi-interlayer was used to achieve active bonding and residual stress relieving. Detailed microstructure characterization and mechanical property assessment were carried out to evaluate the bonding technology. It is found that an obvious transition zone is formed at the interfaces, and the interfacial products are (Ti, Nb), remnant Nb, remnant Cu and Cu(s.s). The shear strength of TiC/Ti-Nb-Cu/304SS joint can be up to 84.6 MPa when it is bonded at 925 °C for 20 min under a pressure of 8 MPa. Failure occurs in TiC cermet near the interface in a brittle manner. The results indicate that Ti/Nb/Cu interlayer can effectively reduce the harmful effects of intermetallic compounds on the joint performance, and the Nb interlayer plays a major role in the relief of the residual stress.