High temperature uniaxial deformation characteristics in Al-Li alloy: Insights into the perspective of microstructure, microtexture and slip system activity

The present study investigates the uniaxial deformation response of Al -Li alloy at elevated temperatures (673 K and 773 K) and nominal strain rate of 0.0001 /s. The alloy exhibits significant softening following deformation at 673 K. On the contrary, a steady state followed by marginal softening is observed in the flow curve and the alloy experiences elongation close to superplastic regime during deformation at 773 K. The microstructure evolution in both the deformed specimens reveals the prevalence of dynamic recrystallization (DRX) via continuous dynamic recrystallization (CDRX) and discontinuous dynamic recrystallization (DDRX) mechanisms which resulted in flow softening. The evolution of Copper {112}(111) as well as S texture {123}(634) components and weakening of Cube texture {001}(100) are observed in both the deformed specimens. Visco-plastic self-consistent (VPSC) simulation reveals that the activation of non-octahedral (NOC) slip systems ({100}(110) and {110}(110)) in conjunction with octahedral (OC) slip system ({111}(110)) predicts the microtexture evolution accurately for both the deformation conditions. The higher activation of NOC slip systems and the simultaneous occurrence of dislocation slip as well as grain boundary sliding accommodated by dislocation slip could be ascribed to the significant improvement in elongation close to superplastic regime at 773 K.