Comparative analysis of the microstructure and mechanical properties of an Al-Cu-Mg-Ag alloy peak-aged at relatively low and high temperatures

The mechanical properties and microstructure have been investigated in the Al-4.35Cu-0.46Mg-0.63Ag-0.36Mn-0.12Ti-0.04Fe alloy (in wt. %) peak-aged at 150 °C and 190 °C. The yield stresses (YS) and the ultimate tensile strength (UTS) were insignificantly higher by 15 MPa and 5 MPa, respectively, after peak-aging at 150 °C for 24 h compared with 190 °C for 1.5 h. Elongation-to-failure (δ) was the same (~6%) in both states. Microstructure analysis showed great differences in the morphology of precipitates within grain/subgrain interiors, as well as in the structure of regions adjacent to grain boundaries (GBs). Relationships between strength/ductile properties and microstructure were discussed.