Study on Microstructure and Properties of Ultra-thin Cu/Al Composite Sheets Using the Cold-Rolled Composite Method at the Microscale

In this paper, an ultra-thin Cu/Al composite sheet with a thickness of 0.08 mm was obtained via the cold-rolling composite method using a four-high micro-rolling mill in the laboratory. The rolling reduction of a single pass was 65%. After the annealing of the ultra-thin Cu/Al composite sheets at temperatures ranging from 350 °C to 500 °C, the interface bonding mode of the Cu/Al composite sheets changed from mechanical bonding to metallurgical bonding, and the bonding strength was significantly improved. The microhardness value at the bonding interface of the ultra-thin Cu/Al composite sheets increases with the increase in annealing temperature. When the annealing temperature is 500 °C, the maximum microhardness value at the bonding interface reached 2.0 GPa. With the increase in annealing temperature, the tensile strength and elongation of the ultra-thin Cu/Al composite sheets decreases significantly. The peel strength of the extremely thin Cu/Al composite sheets increases at first and then decreases with the increase in annealing temperature, and reached the maximum value at an annealing temperature of 400 °C. When the annealing temperature was 400 °C, the tensile and peel properties of the ultra-thin Cu/Al composite sheet reached the best state.