An insight into the interfacial structure and mechanical properties of Al/Cu laminate fabricated through cold spraying and post-treatment

The Al/Cu laminate was fabricated using cold spraying, and post-treatments of annealing and hot compression were conducted to enhance the mechanical properties of the laminate. The interfacial structure, microstructure, and mechanical properties were investigated. It was observed that cold spraying resulted in a mechanical bonding at the Al/Cu interface, and some pores, cracks, and other defects were present. During annealing treatment, intermetallic compounds (IMCs) such as CuAl2, Cu9Al4, and CuAl formed, and the thickness of IMCs increased with increasing temperature. The hot compression enhanced the density of the cold sprayed Cu layer and induced a large number of dislocations at Al and Cu layer, causing a great increase in tensile strength of the laminate. A good combination of tensile strength and elongation was achieved by performing both hot compression and annealing. Additionally, the microcracks generated by internal stress tended to form and propagate in the IMCs layer. IMCs can fill the pores at the interface, thereby increasing the interlayer bonding strength. However, when the thickness of IMCs reached a certain value, the bonding strength declined due to their brittle feature.