Influence of lithium addition on grain boundary behavior and segregation in gas-atomized Al–Li powders: Insights from experimental and first-principles studies

This study investigates the microstructural evolution and lithium (Li) segregation behavior in gas-atomized pure Al and Al-2wt.% Li alloy powders, combining experimental characterization and first-principles calculations. The powders were prepared by gas atomization and subjected to heat treatment for microstructural stabilization. SEM, EDS, and EBSD analyses were employed to characterize particle morphology, grain orientation, and grain boundary (GB) characteristics. The results reveal that the Al-Li alloy exhibits a slightly smaller average particle size (∼17 μm) compared to pure Al (∼20 μm), with the addition of Li influencing the solidification behavior. EBSD analysis shows that pure Al powder exhibits equiaxed grains with random crystallographic orientations, while Al-Li powder displays a weak texture along specific directions, reflecting heterogeneous grain growth. Li segregates predominantly to GBs, such as Σ3, Σ5, Σ7, Σ11, and Σ17, and shows increased segregation after artificial aging at 180°C. First-principles calculations confirm that Li preferentially segregates at these boundaries, with the Σ5(310) boundary showing the strongest affinity. These findings provide insights into the microstructural behavior and mechanisms of Li segregation, with implications for the optimization of Al-Li alloy compositions and heat treatments.