Buckled Brazing of Dissimilar Metals in Wire Laser Additive Manufacturing of Aluminum and Titanium Alloys

Brittle intermetallic compound formation is typically difficult to avoid during fusion joining of dissimilar metals. In this paper, a new approach called buckled brazing wire laser additive manufacturing is proposed to join aluminum and titanium alloys. Ti6Al4V titanium alloy single track was successfully additively fabricated on AA7075 plate, through two liquid pools of the wire and the substrate, separated by a buckled unmelted part of the wire, leading to a mechanically interlocked interface. The effects of manufacturing parameters including laser power, wire-feed speed, platform moving speed and initial contact force between wire and substrate on the surface morphology, internal interface microstructure and formation of intermetallic compounds were investigated through high-speed camera, spectrometer, laser topography, optical imaging, SEM imaging, XRD characterizations along with numerical simulations at different scales. The experimental and numerical results indicate that good surface morphology and sound interface between the two metals can be obtained through the proposed method.