Effect of the annealing process on the formation and growth of intermetallic compounds at the interface of Cu clad Al wire drawn with high area reduction

Abstract

An increase in the annealing temperature and time increased the thickness of the interface and the θ-Al2Cu, η2-AlCu, and γ-Al4Cu9 layers at the interface of a copper clad aluminum wire (CCAW) drawn with a reduction in area (∼95 %), and their growth followed a linear correlation with the square root of the annealing time. The activation energy for growth of θ, η2, and γ phases was 62.1, 68.3, and 83.5 kJ·mol−1·K−1, respectively, as determined using the Arrhenius equation. The slightly lower activation energies for the intermetallic compared to those reported in previous studies were due to the high dislocation density in CCAW induced by the high area reduction during drawing deformation, thereby generating more vacancies to easily diffuse each atom at the low annealing temperature of 400 °C, according to Kirkendall effects.