Interface And Performance Analysis Of Copper - Aluminum Explosive Composites

Both copper and aluminum are good conductor material, they are widely used in electricity, electronics, appliances and other relative fields. Copper content in the earth’s crust is 0.01%. With the shortage of copper resources, our country promoted “replace copper with aluminum” policy since the 1960 s and now “save copper by using aluminum”. Cu-Al bimetallic composite not only has high conductivity and thermal conductivity of copper, but also has the advantages of cheapness, corrosion resistance, light weight and good appearanceThere are many ways to make Cu-Al bimetallic composite. But as electrical fittings, they abide by DL/T346 and is connected by friction welding, flash butt welding, braze, explosive welding. What’s more, Cu-Al transition composite sheets can also be used as electrical fittings. Copper and aluminum are dissimilar materials, so it is difficult to make the bond of them. According to Cu-Al phase diagram, inter-metallic compounds can generate in the welding process of copper and aluminum, which has an effect on the electrical and mechanical performance. In this paper, microstructure, chemical and performance analysis of explosively welded Cu-Al bimetallic composite are conducted and the analysis is used to compare to the Cu-Al bimetallic composite made by other methods. By doing this, the theoretical basis is provided and the manufacturing process is optimized.As the experiment results show, the interface of explosively welded Cu-Al bimetallic composite are wavy, and plastic deformation occurs on both sides of the interface. The hardness of the interface is maximum. When the measuring points move from the interface to base metal, the hardness is descending to the hardness of base metal. There exists obvious vortexes in the interface, which consist of CuAl and CuAl2. Also there exists a 13μm-thick diffusion layer. As the mechanical occlusion effect, wavy interface in stronger than straight interface. So the interface of explosive welding is stronger than those of roll, braze, diffusion welding and flash butt welding. On components of interface, the interface of rolled Cu-Al bimetallic composite consists of Cu-Al solid solution, the interface of “roll+anneling” Cu-Al bimetallic composite consists of 43 CuAl, the interface of braze Cu-Al bimetallic composite consists of solder. the interface of flash butt welded Cu-Al bimetallic composite consists of 43 CuAl, the interface of diffusion welded Cu-Al bimetallic composite consists of Cu-Al solid solution,94 CuAl and 43 CuAl the interface of explosively welded Cu-Al bimetallic composite consists of CuAl and CuAl2. according to the ranking of resistivity, CuAl2>CuAl>43lCuA >94CuAl.so it can be concluded that the conductive loss of explosive welded Cu-Al bimetallic composite is lower than Cu-Al bimetallic composite made by the other methods.The impedance of Cu-Al bimetallic composite made by different methods ranks as follows: diffusion welded Cu-Al bimetallic composite>braze Cu-Al bimetallic composite> flash butt welded Cu-Al bimetallic composite > “roll+anneling” Cu-Al bimetallic composite>rolled Cu-Al bimetallic composite> explosively welded Cu-Al bimetallic composite. It can be concluded that the explosively welded Cu-Al bimetallic composite has the best conductivity. On the possibility, rolled Cu-Al bimetallic composite has the largest possibility to corrode. The ranking of possibility is as below: rolled Cu-Al bimetallic composite > braze Cu-Al bimetallic composite > “roll+anneling” Cu-Al bimetallic composite > explosively welded Cu-Al bimetallic composite > diffusion welded Cu-Al bimetallic composite> flash butt welded Cu-Al bimetallic composite. The corrosion current of “roll+anneling” Cu-Al bimetallic composite is the smallest, which means it is the most corrosion-resistant. And the ranking of corrosion resistance is diffusion welded Cu-Al bimetallic composite>flash butt welded Cu-Al bimetallic composite>explosively welded Cu-Al bimetallic composite>“roll+anneling” Cu-Al bimetallic composite>rolled Cu-Al bimetallic composite> braze Cu-Al bimetallic composite.In summary, explosively welded Cu-Al bimetallic composite has certain advantage over the Cu-Al bimetallic composite made by roll, diffusion welding, braze or flash butt welding on conductivity, mechanical property and corrosion resistance. It can guarantee the safety and energy saving of Cu-Al transition fittings and components.