Effect of Different Aging Processes on the Microstructure and Mechanical Properties of a Novel Al-Cu-Li Alloy

The effects of different aging processes on the microstructure and mechanical properties of a novel Al-Cu-Li alloy have been investigated by X-ray diffraction, scanning electron microscopy and transmission electron microscopy. It is found that the tensile properties of a novel Al-Cu-Li alloy are sensitive to aging processes, which correspond to different microstructures. σ (Al5Cu6Mg2) and T1 (Al2CuLi) phases are the major precipitates for the alloy in T6 aging condition (165 °C/60 h). After duplex aging condition (150 °C/24 h + 180 °C/12 h), σ, θ' (Al2Cu) and T1 phases are detected. Only the T1 phases can be found in the T8 state alloy (6% pre-strain+135 °C/60 h). The failure modes of alloy in T6 and duplex aging conditions are dimple-intergranular fracture, while typical quasi-cleavage fracture in T8 condition.