Interfacial bonding mechanism and pouring temperature effect on Al/Cu bimetal prepared by a novel compound casting process

In this work, the Al/Cu bimetal was prepared by a novel lost foam casting (LFC) compound process, and the effect of pouring temperature on microstructure and mechanical properties of the Al/Cu bimetal was studied. The formation mechanism of the Al/Cu interface was also discussed. Results show that the Al/Cu interface consisted of intermetallic compounds layers (IMCs layers) and eutectic layer. The IMCs layers were identified as Al₂Cu, AlCu, and Al₄Cu₉ phase layers, and the eutectic layer was composed of Al₂Cu, α(Al) and Si phases. The pouring temperature primarily influenced the morphology and size of the IMCs layers and eutectic layer as well as the pore defect in the interface. Based on the cooling curve and the morphology of the IMCs layers, a new formation mechanism of the Al/Cu interface was proposed. The Al/Cu bimetal obtained with a pouring temperature of 800 °C had the relatively highest bonding strength, up to 81 MPa, resulting from its improvement of the IMCs layers. Shear fracture exhibited a brittle fracture nature, mainly initiating with the IMCs layers, and the Si phase also played an important role in the fracture process. (paper)