Synergistic effect of orientation and temperature on slip behavior and precipitation behavior of Al-Cu-Li single crystals

The slip behavior and precipitation behavior of four Al-Cu-Li single crystals with varying orientations at different temperatures were investigated using electron backscattering diffraction (EBSD) and transmission electron microscopy (TEM). The maximum differences in yield strength and ductility of the single crystals at room temperature are 41.6% and 14.7%, respectively. This indicates that the mechanical properties are strongly influenced by the crystal orientation. Moreover, grains with varying orientations exhibit distinct slip characteristics, including slip homogenization, slip localization, and multiple slip. In single crystal SC1, slip localization primarily contributes to its inferior ductility compared to other grains. Nevertheless, during deformation at 250 °C, the distinct morphology and distribution of precipitates in the crystals are also correlated with orientation, which causes the increase in the maximum elongation difference to 20.8% in all selected single crystals. Notably, SC1, with a precipitate volume fraction of 2.65%, exhibits more severe slip localization compared to room temperature conditions, while SC2, with a precipitate volume fraction of 4.79%, demonstrates cross-slip characteristics, significantly enhancing the plastic deformation capacity of the Al-Cu-Li alloy.