Effects of pre-deformation on the precipitation behavior of Al-Cu-Li-（Mg-Ag） alloy during artificial aging

The effect of pre-deformation on the precipitation behavior of Al-Cu-Li and Al-Cu-Li-（Mg-Ag） alloys during artificial aging (RA) was studied by the Vickers hardness test, transmission electron microscopy (TEM) and differential scanning calorimetry (DSC). The results showed that the precipitation of the θ' phase was the main phase after peak-aging in Al-Cu-Li alloy. Moreover, the dislocation caused by pre-deformation was beneficial to the precipitation of θ' phase in Al-Cu-Li alloy after aging but had little effect on the T₁ phase. For the Al-Cu-Li-（Mg-Ag） alloy, the precipitation of the T₁ phase and θ' phase was promoted by pre-deformation during RA. After the addition of trace Mg and Ag solute elements, the precipitation phase of Al-Cu-Li-Mg-Ag alloy was mainly the T₁ phases after peak-aging, with fewer θ' phases. The number density of the T₁ phases and θ' phases increased after the pre-deformation aging of the Al-Cu-Li-（Mg-Ag） alloy, that is, the pre-deformation promoted the precipitation of the T₁ phases and θ' phases simultaneously. Within the pre-deformation range of Ɛ = 0 ~ 3%, the number density of the T₁ phases increased with the increment of pre-deformation, and their size was also becoming more uniform and smaller. Thus, the alloy could obtain more excellent mechanical properties.