A new method for fabricating Mg/Al alloy composites by pulse current-assisted rolled welding

•The Mg/Al composite plates are produced by a pulse current-assisted rolled welding.•The metal droplets are squeezed in the interfacial cross section.•The eutectic reaction mechanism is found at the interface.•A “serrated” structure interlayer is formed at the interface during the process.•The press-shear strength of the Mg/Al composite plate reaches 70.37 MPa. Pulse current-assisted rolled welding (PCARW) technology was applied for the fabrication of an Mg/Al alloy composite plate. Compared with traditional hot rolling, this process is characterized by rolling in an atmospheric environment instead of vacuum heat rolling or pack-rolling. The results showed that molten metal droplets were squeezed in the interfacial cross section, and the interfacial transition layer was formed with a serrated morphology. The formation of this special structure was due to element diffusion and eutectic reactions at the interface. A recrystallized fine-grained microstructure and shear bands (SBs) were found at the Mg alloy side near the interface. To summarize, it can be proven that the instantaneous transition liquid phase was formed at the bonding interface during rolling, and then the welded interface was obtained. Furthermore, the press-shear strength of the Mg/Al composite plate reached 70.37 MPa. Combined with the fracture morphologies, the fracture failure path was speculated to be along the interface between the transition layer and Mg alloy matrix and then pass through the transition layer along the cracks to the Al alloy matrix side.