Influence of Filler Alloy on Microstructure and Properties of Induction Brazed Al/Cu Joints

Abstract

This work aimed to clarity the influence of filler alloy on microstructures and properties of induction brazed Al/Cu joints. It was found that the alloying elements in the filler alloy changed the morphology and phase type of interfacial layer in the joint. Mg converted the native Al2O3 film into MgO and stopped the re-oxidation of aluminum. However, excessive Mg caused planar inter-metallic compounds (IMCs) to become wavy, which decrease the ductility of the joint. A suitable amount of Cu and Si removed residual oxide film and resulted in a thin planar IMCs layer, which is beneficial to Al/Cu joint. Al-8Si-4Cu-2Mg-1Ga-0.05Ce filler foil produced an excellent joint consisting of a 2μm Cu9Al4/CuAl2 planar layer and free from oxide film. The tensile strength of the joint is higher than that of aluminum. The bend angle is higher 130°. The electrical resistivity of the joint is lower than the theoretical value.

Keywords

• Copper
• aluminum
• induction brazing
• inter-metallic compound
• filler alloy