Creep behavior and mechanical properties of Al-Li-S4 alloy at different aging temperatures

Abstract

Creep age forming techniques have been widely used in aerospace industries. In this study, we investigated the effect of aging temperature (143 °C–163 °C) on the creep behavior of Al-Li-S4 aluminum alloy and their mechanical properties at room temperature. The mechanical properties were tested by tensile testing, and the microstructural evolution at different aging temperatures was examined by transmission electron microscopy. Results show that the creep strains and the room-temperature mechanical properties after creep aging increase with the aging temperature. As the aging temperature increases, the creep strain increases from 0.018% at 143 °C to 0.058% at 153 °C, and then to 0.094% at 163 °C. Within 25 h aging, the number of creep steps increases and the duration time of the same steps is shortened with the growth of aging temperatures. Therefore, the increase in aging temperatures accelerates the progress of the entire creep. Two main strengthening precipitates θ′ (Al2Cu) and T1 (Al2CuLi) phases were characterized. This work indicates that the creep strain and mechanical properties of Al-Li-S4 alloys can be improved by controlling aging temperatures.