Effect of Rolling Temperature on Microstructures and Mechanical Properties of Sc-Containing Al–Cu–Li Alloy

The influences of various deformation temperatures on the microstructures and tensile behavior of Sc-containing Al–3.2Cu–1.5Li alloy were investigated by SEM, XRD, EBSD, TEM and tensile tests. The results indicated that the grain structures in hot-rolled and T6-treated samples are primarily composed of substructural characteristics. The fine and stable dispersed Al₃(Sc,Zr)/Al₃(Li,Sc,Zr) phase precipitated along (sub)grain boundaries or dislocations contributes significantly to the high recrystallization resistance. Meanwhile, the formation of nanoscale Al₃(Sc,Zr)/Al₃(Li,Sc,Zr) particles efficiently prevented the growth of recrystallized grain during hot rolling and T6 heat treatment. Furthermore, with the temperature increasing, the ultimate tensile strength (UTS) first increases and then declines, while the elongation (EL) has a rising tendency and then reaches the saturation stage. The Sc microalloyed sample rolled at 420 °C possesses excellent mechanical property (UTS = 480.4 MPa and EL = 13.0%) due to the comprehensive results of fine grain, precipitation, dispersion and dislocation strengthening.