Microstructures evolution and mechanical properties disparity in 2070 Al-Li alloy with minor Sc addition
(1. School of Materials Science and Engineering, Central South University, Changsha 410083, China;
2. Science and Technology on High Strength Structural Materials Laboratory, Central South University, Changsha 410083, China)
2. Science and Technology on High Strength Structural Materials Laboratory, Central South University, Changsha 410083, China)
Abstract: The microstructures and mechanical properties of Al-3.35Cu-1.2Li-0.4Mg-0.4Zn-0.3Mn-0.1Zr (mass fraction, %) alloy with Sc addition or free Sc were investigated through tensile test, SEM, EPMA and TEM. The addition of 0.082% (mass fraction) Sc element leads to the formation of Cu-rich and Sc-contained nano-sized Al3(ScZr) particles and W phase particles. The Al3(ScZr) particles can inhibit recrystallization to a certain extent and impede recrystallized grain growth during solution treatment. It is found that W phase cannot dissolve in supersaturated solid solution during the solution heat treatment, and the Cu content in the solutionized matrix is decreased, which causes a decrease in the fraction of Cu-contained strengthening precipitates with T1 (Al2CuLi) and θ'''' (Al2Cu) under T8 aging condition. Due to the formation of the W phases, the small Sc addition causes a little reduction in the strength.
Key words: Al-Li alloy; Sc addition; microstructure; mechanical properties