Effect of annealing temperature on microstructure and bond strength of cast-rolling Cu–Al clad plates

Abstract

Effect of different annealing temperatures on evolution of microstructure in copper-aluminum clad plates prepared by cast-rolling were investigated using scanning and transmission electrical microscopy, and x-ray diffraction. Peeling tests were conducted to characterize the bond strength of prepared clad plates. Results showed that with the increase in annealing temperature, the bond strength of the 8 mm thick copper-aluminum clad plates first increased and then decreased. When the annealing temperature was 250 °C–300 °C for 3 h, CuAl2 was formed at the interface, promoting atomic diffusion and improving the bond strength. However, when the annealing temperature was 300 °C–400 °C for 3 h, providing enough energy for a new Cu9Al4 intermetallic phase formed at the interface, and the thickness of the interface layer increased from about 1 μm to 11 μm, while the bond strength decreased from 42 ± 0.8 N·mm−1 to 12 ± 1 N·mm−1. The fracture pattern of the clad plates extensible to brittle with the annealing temperatures from 300 °C to 450 °C for 3 h. According to the experimental results, the optimal annealing temperature for copper-aluminum clad plates prepared by cast-rolling is 300 °C for 3 h.