Diffusion bonding of Al7075 to Ti–6Al–4V using Cu coatings and Sn–3.6Ag–1Cu interlayers

Two dissimilar aerospace alloys Ti–6Al–4V and Al7075 were joined using a combination of Cu coatings and Sn–3.6Ag–1Cu interlayers. The Cu coatings were electrodeposited onto the Al7075 and Ti–6Al–4V surfaces. Bonds were made at 500 °C and 1 MPa for various bonding times. Scanning electron microscopy (SEM), energy dispersive spectroscopy (EDS), X-ray digital mapping and X-ray diffraction (XRD) were used in this work to investigate the compositional changes across the joint region. Differential scanning calorimetry (DSC) analysis was used to study the mechanism of bonding. The results show that the Sn–3.6Ag–1Cu interlayer produces sound joints when a thin coating of Cu was deposited onto the alloy surfaces. The concentration of Sn reduces at the joint center with increasing bonding time. The strength of the bonds increases with increasing of bonding time.