Metallurgical parameters controlling the microstructure and hardness of Al-Si-Cu-Mg base alloys

► Microstructure and hardness of Al-Si-Cu-Mg type 319 alloys. ► Formation of Mg2Si, Q-Al5Mg8Cu2Si6, π-Al8Mg3FeSi6, Al2Cu phases. ► Effects of alloy type, Mg content, cooling rate, heat treatment (T6, T7). ► Mg, Cu, and high cooling rate (DAS 24 μm) improve hardness in T6 condition. ► Experimental alloys show higher hardness than industrial alloys.