Formation and growth of Cu-Al IMCs and their effect on electrical property of electroplated Cu/Al laminar composites

Cu/Al laminar composite was prepared by dipping Zn layer and then electroplating Cu thick layer on pure Al sheet. During annealing the Cu/Al composites at temperature from 473 to 673 K, the Cu/Al interfacial diffusion and reaction and its kinetics and also the electrical resistivity of the composites were studied. The results show that no Cu-Al IMC layer is observable as the composites are annealed at 473 K for time till 360 h, indicating that the Zn intermediate layer can effectively suppress the Cu/Al interfacial diffusion. However, as the composites are annealed at 573 K and above, Zn atoms in the Zn layer dissolve into the Cu layer. Tri-layered reaction product of CuAl2/CuAl/Cu9Al4 then forms from the Al side to the Cu side. The IMC layer follows the diffusion-controlled growth kinetics. Electrical resistivity of the Cu/Al composites increases with the increase of the annealing temperature and time.