Interface Microstructure and Strength Properties of the Diffusion-Bonded Joints of Titanium ∣Cu Interlayer ∣ Stainless Steel

In the present study, copper was used as an intermediate material in diffusion bonding between titanium and stainless steel. The process was carried out in the temperature range of 850 °C to 1000 °C for 60 minutes and at 900 °C for 30 to 150 minutes under the compressive stress of 3 MPa in a vacuum. The effects of temperature and time on the microstructure of Ti ∣Cu ∣ stainless steel diffusion-bonded joints were studied. The interface microstructures of the bonded assemblies were observed in optical and scanning electron microscopes and an electron probe microanalyzer. Formation of various types of reaction products near the interface was detected using the X-ray diffraction technique. The maximum tensile and shear strength of ∼101 pct of that of Ti and of ∼86 pct of that of Ti, respectively, along with ∼8.5 pct elongation, were obtained at 900 °C for 60 minutes. Observation of fracture surfaces demonstrates that failure takes place through the SS-Cu interface.