Study by nanoindentation of the influence of the manufacturing process on the mechanical properties of Copper-Clad Aluminum wires

We studied the influence of the architecture of Copper-Clad Aluminum (CCA) wires produced by cold-drawing process, on the mechanical properties of materials, and the development of intermetallic compounds at the interface after annealing. Simple and architectured-CCA (A_CCA) rods, fabricated by stacking and re-drawing of original CCA wires, have been characterized before and after a thermal treatment. Nanoindentation tests, performed to map the hardness and the elastic modulus at the microscale, allow to well catch the recrystallization phenomenon, which takes place in both the Cu and the Al subjected to severe plastic deformation, as well as the formation of three intermetallic compounds (IMC) at the interface. Our measures underline that the mechanical properties of all the components involved in the wires, i.e., Cu, Al, and eventually the IMC developing after annealing, are only slightly influenced by the structuration of the wires. IMC developing at the Cu/Al interfaces present a high hardness, and might deteriorate the mechanical properties of the wires, even more for A_CCA wires, which exhibit more interfaces that the traditional CCA samples.