Optimizing recrystallization behavior induced by Mn micro-alloying for reduced anisotropy in rolled Al-Cu-Li alloys

The application of rolled Al-Cu-Li alloy is significantly limited by its anisotropy of mechanical properties, which is dominated by microstructures including grain morphology and textures. In this work, the Mn micro-alloying effect with different additions of 0 similar to 0.8 wt% on recrystallization behavior, microstructural evolution, and mechanical anisotropy in rolled Al-Cu-Li alloys is investigated. The results reveal that Mn-free alloy exhibit a high volume fraction (53.4 %) of the deformation textures, including Brass ({110}<1 <(1)over bar> 2>), S ({123}<63<(4)over bar> >), and Copper ({112}<11<(1)over bar> >), resulting in a large anisotropy in mechanical property. With the addition of Mn, the number density of Al-Cu-Mn precipitates is increased in the as-rolled alloy, which promotes the recrystallization tendencies during solution treatment and decreases the anisotropy. Among the experimental alloys, the 0.4 wt% Mn-containing sample exhibits a large fraction (55.6 %) of grains with no preferred orientation and a evident recrystallization textures including Cube ({100}<001>) and Goss ({110}<001>). This contributes to good comprehensive mechanical properties (YS = 551 MPa, UTS = 583 MPa, EL = 12.0 %) with a much lower anisotropy. However, an excessive addition of 0.8 wt% Mn leads to the grain coarsening and deteriorative mechanical properties. Based on the above results, the relationship between the texture and anisotropy is established using the effective Schmid factor and the equivalent slip system number.