text: Al-Si-Cu-Mg alloys form Al5FeSi- plate like intermetallic phases like -Al8Fe2Si, Al2Cu, etc. The size and morphology of these intermetallic phases in these alloys control the mechanical properties of these alloys, especially strength and ductility. The size of these phases depends on the secondary dendrite arm spacing, as well as the Si content of the alloy, of the primary phase in the micro structure.