Study On Cold-rolling Cladding And Interface Microstructure Of Cu/Al-Zn Clad Strip

With the rapid development of science and economy today, single material has been difficult to satisfy modern society in combination properties. Therefore, the research of dissimilar metal clad technology has been of great importance. In this study, Cu/Al-Zn clad strips were made by cold-rolling, The interfacial reaction between Cu and Al-Zn, the growing regularity of intermetallic compounds and the influence on interface bonding performance in the heat treatment phase were analyzed. The effect of annealing schedule and Zn on the growth of the intermetallic compound was discussed.This paper researched in the formation and growth of the intermetallic compounds with different annealing schedules and found that:(1) The interface layer grows faster when temperature increase. Along with the extension of heat preservation time, the growth of the interfacial intermetallic phase process is:first the induction period, then the nucleation and growth of the island new phase, last the new phase links together and grows perpendicular to the interface;(2) During heat treatment time, the first reaction product CuAl2is presumed, then followed the Cu9Al4, and finally CuAl. With the increasement of heat preservation temperature, the Cu9Al4grows faster than the CuAl2.This paper researched in the effect of Zn to the intermetallic compound and the interface bonding performance. It is showed that on the one hand, Zn refine the interfacial grain size, the grain boundaries increase, the diffusion of Cu、Al element is promoted, on the other hand, Zn reduces the diffusion activation energy of Al、Cu, and promotes the growth of the interfacial layer. At lower temperature, it is good for the physical metallurgy combination of Cu/Al, while at higher temperature, it will have a negative effect on the interface bonding performance, for the existence of Zn advances the formation of the intermetallic compound. When the zinc content in the aluminum plate is constant, we obtain the highest interface bonding strength after1h at300℃. At lower temperature(200℃,300℃), with the increasing of the content of Zinc in the substrate, the bonding strength increases. As the increase of the holding temperature(400℃,500℃) and the holding time, the bonding strength is reduced. What’s more, the more the content of Zn in the the aluminum plate, the worse the bonding strength is. The paper found that the closer to the transition zone in the aluminum side, the lower the microhardness is. While, the closer to the transition zone in the copper side, the higher the microhardness is. That is because:(1) As the content of zinc is reduced with the spreading of atoms, general lattice distortion is weaken, then the microhardness in the Al side close to the interface get lower;(2) As the Al atoms and Zn atoms spread to the copper side, the closer to the interface in the copper side, the higher the mircrohardness is for the formation of solid solution.