Impact of temperature and deformation gradient on the joining zone formation of laser roll-bonded bimetals

The process of laser roll-bonding facilitates the production of bimetals with different geometries and material combinations. Contrasting the classical cold and warm roll-bonding processes, only the surfaces of the two bonding materials to be bonded are heated to the necessary process temperatures using laser energy. As a result, deformation is concentrated on the material volumes near the joining zone. When pairing the materials aluminium and copper, this mechanism becomes visible in metallographic sections. Inclusions containing copper are apparent here in the aluminium near the joining zone. As a result of aluminium flowing against the direction of rolling (formation of a quasi-stationary and convecting bulge), small melt droplets are shorn off the copper surface. At the same time, the melt droplets are integrated into the aluminum. This suppresses the formation of intermetallic phase seams on the material transition making very ductile material composites possible.