Effects of Transition Layer on Bending Resistance in Copper-Clad Aluminum Composite Casting

The performance of the transition layer in a Cu/Al composite casting directly affects the quality of subsequent plastic deformation processing; however, there are no universal or standardized measurement indices for the performance of the transition layer. In this study, Cu/Al composite castings were prepared using the pouring aluminum method, and the resulting solidification microstructures on the bending resistance were investigated. The results of this study lay a theoretical foundation for the development of the plastic processing technologies of these composite castings. A thinner transition layer in the Cu/Al composite casting led to improved bending resistance. In addition, for a fixed total thickness of the transition layer, the bending resistance was mainly controlled by the γ/β interface and β + eutectic (α + β) microstructure, and the thickness of the γ phase had a negligible effect on the bending resistance. The γ/β interface cracked first when the transition layer bore the tensile and shear stress during the bending process, which resulted in the transition layer easily separating from the copper. The bending resistance of the transition layer can be feasibly judged by measuring the bending angle of the specimen tip, which can be easily performed when the specimen bends toward the aluminum direction, suggesting that our proposed method has considerable practical significance.