The influence of Cu/Mg atomic ratios on precipitation scenarios and mechanical properties of Al-Cu-Mg alloys

The mechanical properties and precipitation scenarios of Al-Cu-Mg alloys with different Cu/Mg atomic ratios have been investigated. We show that the designed alloy with an intermediate Cu/Mg ratio has better mechanical properties due to the coexistence of S and θ′ series precipitates. Compared to the commercial alloys with higher or lower Cu/Mg ratios, the evolution of θ′ precipitates in the designed alloy is slowed by the S phase, resulting in a longer duration of higher hardness with three peaks.