Solidification structures and properties of cast samples of zinc-aluminum alloys and composites

Zinc-Aluminium alloys and composites containing different Silicon and Copper concentrations were cast and analysed. The results show that silicon and copper follow opposite behaviours. Silicon is found as thick plates inside the dendrites while copper is found in the interdendritic regions as laminar intermetallic eutectic. Silicon precipitates for all the concentrations with a tendency to coalesce at higher concentrations while copper is completely dissolved at low concentrations. The addition of silicon carbides particles in the alloys increases the hardness. In addition there is an indication that the particles reduce the size of the solidification microestructure.