Heat Treatment of Aluminum-Titanium-Compounds Made by Co-Extrusion and Friction Welding

The combination of aluminum and titanium alloys allows for designing lightweight structures with tailor-made properties at the macroscopic global as well as at the microscopic scale. In this context both co-extrusion and friction welding offer a great potential for advanced solutions for products with material combinations of aluminum and titanium. While titanium alloys show particular high mechanical strength and good corrosion resistance, aluminum alloys provide a considerable high specific bending stiffness along with low materials costs. Since the mechanical properties of metallic composites highly depend on the existence and formation of the intermetallic layer in the bonding zone compounds were processed by co-extrusion and friction welding and subsequent heat treatment to investigate the strength and the composition of the bonding zone. The results of friction welded samples concerning the intermetallic layer that was formed during heat treatment were compared with those directly after the co-extrusion. In this layer an enrichment of elements which origin from the aluminum alloy, particularly silicon, was observed. The layer was characterized by optical microscopy, scanning electron microscopy as well as electron probe micro analysis. The mechanical properties were determined by tensile tests.