Evolution of Interface Microstructure and Mechanical Properties of Titanium/304 Stainless Steel Diffusion Bonded Joint Using Nb Interlayer

In the present investigation, the evolution of interface microstructure and mechanical properties of diffusion bonded joints of titanium to Type 304 stainless steel with a niobium interlayer were studied. The joints were processed in the temperature range of 800 to 1000°C for 0.5 h in vacuum. The stainless steel/niobium interface was free from intermetallic phase up to 900°C; however, Fe2Nb+Fe7Nb6 phase mixture was observed at and above a processing temperature of 950°C. The niobium/titanium interface was free from intermetallic compounds at all processing temperatures. A maximum tensile strength of 297 MPa (~93% of Ti) and shear strength of 217 MPa (~75% of Ti) along with a 6.9% ductility were achieved, when processed at 900°C processing temperature. The failure of bonded samples took place through the stainless steel–niobium interface at all processing temperatures during loading.