Interface microstructure and strength properties of diffusion bonded joints of titanium-Al interlayer-18Cr-8Ni stainless steel

In the present investigation, diffusion bonded joints between titanium and 18Cr-8Ni stainless steel using 120 μm thick Al interlayer were produced at 650 deg. C temperature for 15, 30, 45, 60, 90, 120, 150 and 180 min under 4 MPa pressure in vacuum. The interface microstructures of the bonded assemblies were observed in a scanning electron microscope using backscattered mode with energy dispersion spectroscopy and X-ray diffraction technique. Al2Fe layer intermetallic has been observed at the SS-Ti interface, however at the Al-Ti interface AlTi + Al3Ti phase mixture was formed for all the processing times. The maximum tensile strength of ∼266 MPa along with 5.6% elongation was obtained for the diffusion couple processed for 90 min and the bonded samples were fractured through the Al-Ti interface for all the processing times.