Effect of applied stress level on anisotropy in creep-aging behavior of Al-Cu-Li alloy

In the present work, the anisotropic creep aging (CA) behavior and microstructural evolution of Al-Cu-Li alloy are investigated under different stress levels. The results indicate that as the stress level increases, the anisotropic creep behavior of Al-Cu-Li alloy changes significantly. As the applied stress level increases, the in-plane anisotropy (IPA) value of creep strain decreases and then increases. In addition, the strength also exhibits sig-nificant anisotropy, and as the applied stress level increases, there are differences in the strength changes of samples with different orientations at different creep aging times. Electron backscatter diffraction (EBSD), Energy-dispersive x-ray spectroscopy (EDS) and transmission electron microscopy (TEM) methods are used to study the evolution of texture and microstructure, as well as their effects on the anisotropy evolution of mate-rials. Microscopic observation reveals that the anisotropy changes in creep and strength can be attributed to the difference in dislocation density and grain boundary slip phenomenon during the initial creep stage in samples with different orientations, as well as the stress orientation effect of precipitated phases, especially T1 phase. The study reveals a new mechanism of anisotropic CA mechanism in Al-Cu-Li alloy under different applied stress levels.