Interface microstructure and strength properties of Ti–6Al–4V and microduplex stainless steel diffusion bonded joints

The diffusion bonding of Ti–6Al–4V alloy and micro-duplex stainless steel was carried out in the temperature range of 850–1000 °C for 45 min in vacuum. The influence of bonding temperature on the microstructural development, micro-hardness and strength properties across the joint region was determined. The layer wise σ phase, λ + FeTi and λ + FeTi + β-Ti phase mixtures were observed at the bond interface when the joint was processed at 900 °C and above temperature. The maximum tensile strength of ∼520.1 MPa and shear strength of ∼405.5 MPa along with 6.8% elongation were obtained for the diffusion couple processed at 900 °C. Fracture surface observation in scanning electron microscopy (SEM) using energy dispersive X-ray spectroscope (EDS) demonstrates that, failure takes place through λ + FeTi phase when bonding was processed at 900 °C, however, failure takes place through σ phase for the diffusion joints processed at and above 950 °C.