Heat Treatment of Titanium-Aluminum-Compounds Made by Co-Extrusion of Asymmetric Compound Profiles

Combining different materials allows designing lightweight structures with tailor-made properties at the macroscopic as well as at the microscopic scale. In this context co-extrusion by lateral angular co-extrusion process (LACE) offers a great potential for advanced products by joining different light alloys, such as titanium and aluminum alloys. While titanium alloys show particular high mechanical strength values and a good corrosion resistance, aluminum alloys feature a considerable high specific bending stiffness at low materials costs. Within the presented research study metallic compounds were manufactured by co-extrusion using a LACE process. Since the mechanical properties of metallic composites highly depend on the existence and formation of an intermetallic layer, the bonding zone of the compounds were investigated. Experiments were carried out at the example of the material combinations Al99.5 & Ti99.2 and AlSi1MgMn & Ti99.2, respectively. The results of co-extruded samples concerning the intermetallic layer that was formed during heat treatment were compared with those directly after the co-extrusion. The investigations were focused on the formation of the bonding zone after both co-extrusion and the subsequent heat treatment. The bonding zone was characterized by scanning electron microscopy as well as electron probe micro analysis. Finally, the bond strength of each compound variant was determined and evaluated.