Microstructure and mechanical properties of interrupted aged cast Al–4.5Cu–3.5Zn–0.5Mg alloy

Abstract This study investigated the microstructure and mechanical properties of interrupted aged cast Al–4.5Cu–3.5Zn–0.5Mg alloy. Small Cu-rich Guinier–Preston (GP) zones and Mg-rich clusters (GPI zones) formed during the initial aging stages. Zn addition promoted the formation of a uniformly dispersed fine plate-like Ω phases in the matrix. The microstructure of the interrupted aged alloy comprised fine highly dense Ω and θ' phases within the matrix, compared to that of isothermal aged alloy. The enhanced mechanical properties of the cast Al–4.5Cu–3.5Zn–0.5Mg alloy were attributed to this microstructure.