Aging behavior of Al-Li-(Cu, Mg) alloys processed by different deformation methods

Structural features and aging behavior of AlLi, Al-Li-Cu and Al-Li-Mg alloys under different equivalent strains (ε ) were investigated. Following solid-solution treatment, high-pressure torsion (HPT), asymmetric rolling (ASR) and cold rolling (CR) were adopted to introduce high, middle and low amount of strains to Al-Li-(Cu, Mg) alloys. After deformation, for the HPT processed alloys under high equivalent strains, the highest as-deformed hardness was obtained. Transmission electron microscopy (TEM) revealed that the grain size was refined to 210 nm, 120 nm and 150 nm, respectively. Under severe plastic deformation condition (ε > 30), the AlLi alloy lost age-hardenability, however, the aging of the asymmetric rolled AlLi alloys increased the hardness further and the highest hardness was obtained in this alloy. For the Al-Li-Cu and Al-Li-Mg alloys, a further increase in hardness was achieved by aging the as-deformed alloys, regardless of the equivalent strains. Meanwhile, the peak hardness increases with increasing the equivalent strains. During aging treatment, the behavior of the precipitates was discussed in the present work.