Achieving high-strength metallurgical bonding between A356 aluminum and copper through compound casting

Due to stable surface oxides on the solid copper surface and the ease of forming Al2O3 films at the aluminum melt surface, it is difficult to achieve high-strength metallurgical bonding between the two materials through compound casting. In this research, a novel surface coating method for the copper inserts, namely hot-dip Sn-coating, has been applied. Through this method, a high-quality bond between a cast aluminum alloy A356 and commercially pure copper was achieved through a gravity compound casting process. Tensile tests showed that a maximum ultimate tensile strength (UTS) of 90.8 MPa could be obtained for the bimetal interface. Microstructures formed in the aluminum/copper interface were studied by optical- and scanning electron microscopy, while a sessile drop wetting test was used to study the wettability between the aluminum melt and Sn-coated copper substrates. The effects of Sn-coating on the wettability and the formation of interfacial microstructure were discussed. •Continuous metallurgical bond was achieved in aluminum/copper compound castings.•Sn-coating of copper significantly improved wetting between aluminum and copper.•Ultimate tensile strength of 90.8 MPa was measured for the Al/Cu castings.•Effect of the Sn coating layer was discussed.