Microstructure of aluminum/copper clad composite fabricated by casting-cold extrusion forming

An aluminum/copper clad composite was fabricated by the casting-cold extrusion forming technology and the microstructures of the products were observed and analyzed. It is found that aluminum grains at the interface are refined in the radial profiles of cone-shaped deformation zone, but the grains in the center maintain the original state and the grain size is non-uniform. A clear boundary presents between the refined area and center area. In contrast, the copper grains in the radial profiles have been significantly refined. In the center area of the copper, the grains are bigger than those at the boundary. On the surface of the deformable body, the grain size is the smallest, but with irregular grain morphology. After the product is entirely extruded, all the copper and aluminum grains are refined with small and uniform morphology. In the center area, the average diameter of aluminum grains is smaller than 5 mu m, and the copper grain on the surface is about 10 mu m. At the interface, the grain size is very small, with a good combination of copper and aluminum. The thickness of interface is in the range of 10-15 mu m. Energy spectrum analysis shows that CuAl3 phase presents at the interface.