Effect of Annealing Holding Time on Microstructure, Interface Diffusion Behavior, and Deformation Behavior of Cu/Al Composite Foil After Secondary Micro-Rolling

In this study, the Cu/Al composite foil with a thickness of 0.04 mm was prepared by a combination of secondary micro-rolling and intermediate annealing process. The influence of different holding times (40, 60, and 80 min) at an annealing temperature of 400 °C on the microstructure, interfacial diffusion behavior, and deformation behavior of the secondary micro-rolled Cu/Al composite foil was systematically investigated using scanning electron microscopy with energy dispersive spectroscopy (SEM-EDS) and X-ray diffraction (XRD). The experimental results showed that as the holding time increased, the grain sizes of both Cu and Al in the first and second micro-rolled samples and the thickness of the interfacial diffusion layer were increased, meanwhile the interfacial intermetallic compounds were consistently identified as CuAl₂, Cu₄Al, and Cu₉Al₄ at different holding times. When the holding time reaches 80 min, (CuAl) appears in the secondary micro-rolled specimens. Furthermore, with the increase in holding time, the protrusion height of the edge profile and the degree of edge cracking in the secondary micro-rolled specimens increase, demonstrating that the edge deformation behavior of the material was significantly influenced by the holding time.