Rotary swaged laminated Cu-Al composites: Effect of structure on residual stress and mechanical and electric properties

Abstract

This study focuses on the investigation of uniquely sequenced Cu-Al clad composite wires, which are considered as perspective materials for applications within a wide range of industrial and commercial branches. The wires were produced by rotary swaging under variable temperature (at 20 °C and 250 °C). The required diameter of the final wire was 5 mm, however, detailed analyses were performed on 10 mm, 7.5 mm, 6 mm and 5 mm samples. The swaged composite wires were studied from the viewpoints of deformation behaviour, structure and mutual interfaces, and electric and mechanical properties via scanning and transmission electron microscopy and neutron diffraction, testing of electrical resistivity, and mechanical testing with implemented acoustic emission detection. The results showed non-negligible effects of both the variables/influencing factors (swaging degree and temperature) on the investigated parameters. The development of intermetallics was observed at the interfaces of samples swaged with high swaging degrees, but only at 250 °C. These intermetallics provoked signal activity during acoustic emission detection and deteriorated the electric conductivity. On the other hand, substantial work hardening occurring during swaging at 20 °C also decreased the conductivity. By these reasons, the electric properties were the poorest for work hardened samples with occurring intermetallics. Both the final 5 mm composites exhibited satisfactory bonding of both the components and recrystallized structures with ultra-fine grains ensuring the ultimate tensile strength higher than 200 MPa.