Microstructural and mechanical characterization of Al/Cu interface in a bimetallic composite produced by compound casting

Abstract

The bimetal set (Al/Cu) with Cu wire with 2.0, 2.5, and 3.0 mm diameters were cast at different casting temperatures and solidification times through the compound casting method. The microstructure of solid/liquid diffusion bonding at the Al/Cu interface was investigated, and the shear strength of the Al/Cu interface was measured by punch test. By characterizing the diffusion layer, the optimum parameters of the compound casting, including the casting temperature and the solidification soaking time, as well as the Cu wire diameter, were acquired. The intermetallic compounds (IMCs) such as CuAl2 were observed in the diffusion layer. The types of intermetallic phases and diffusion layer thickness affect the hardness and the shear strength. The result of casting at 680 °C and solidification soaking time of 15 s for 3 mm Cu wire, shows that IMCs increased the micro-hardness of the Al/Cu bimetal up to 328 HV at the Al/Cu interface. Also, increasing the solidification soaking time at a constant temperature resulted in a growth of the interface layer’s thickness, which exhibits a lamellar eutectic microstructure containing IMCs. Furthermore, this action caused an increase in the shear strength.