Interface formation in aluminium–aluminium compound casting

An inherent difficulty in joining aluminium is its natural oxide layer, which results in insufficient wettability. In this project we describe a “compound casting” process where an aluminium melt is cast onto a solid aluminium substrate. Both the solid substrate and the melt contain various alloying elements (Mg in the substrate; Cu, Si, and Zn in the melt). Compounds with flawless and continuously metallic interfaces can be produced successfully by replacing the oxide layer with a zinc layer. Diffusion of alloying elements leads to heat-treatable microstructures in the vicinity of the joining interfaces. The experimental results coincide well with the diffusion zone extensions simulated by means of DICTRA calculations.