Laser butt welding of AA7075 aluminium alloy and Ti6Al4V titanium alloy using a Cu interlayer

Abstract

Laser welding of AA7075 and Ti6Al4V, two very different aerospace alloys, was performed with a copper (Cu) interlayer to avoid the brittle Ti–Al intermetallics. The joint was formed owing to the diffusion of Cu into the AA7075 alloy and limited diffusion in Ti6Al4V alloy, followed by eutectic formation at the AA7075/Cu interface. Microstructural and energy dispersive spectroscopy (EDS) analyses of the joint area revealed the presence of eutectic phases at grain boundaries inside the AA7075 fusion zone (FZ). An interfacial Cu3Ti2 phase formed at the solid-state Ti6Al4V/Cu interface. A robust and sound joint was achieved through the effective utilisation of Cu as an interlayer.