Interfacial phenomena in magnesium/aluminum bi-metallic castings

This paper summarizes the bi-metallic experiments using a high-vacuum test apparatus to understand the interfacial phenomena between Mg (AM60) and Al (A390) samples. The test results show significantly improved wetting and metallurgical bonding between the molten magnesium and aluminum substrate when a “zincate+galvanizing” surface treatment was applied. This surface treatment removes the intrinsic Al2O3 layer on the aluminum substrate and, in turn, forms a very thin metallic zinc film on the substrate. Interfacial reactions between the aluminum substrate and the molten magnesium led to the improved metallurgical bonding and significantly improved shear strength in the bi-metallic samples with “zincate+galvanizing” surface treatment. However, long reaction times led to the formation of excessive intermetallic compounds at the interface, which reduced bond strength.