<p>This study investigates the effects of rare earth erbium (Er) modification and annealing treatment on the microstructure, mechanical properties, and electrical conductivity of 8030 aluminum alloy. The alloy’s microstructure was analyzed using scanning electron microscopy (SEM), transmission electron microscopy (TEM), and electron backscatter diffraction (EBSD). Hardness, tensile strength, and electrical conductivity were measured to evaluate the mechanical properties and performance of the alloy. The results indicated that the addition of Er reduced the size of the Al₃Fe phase, and transformed its typical elongated, claw-like morphology into a more spherical shape. Furthermore, the L1₂-structured Al₃Er phase preferentially nucleated at the liquid-solid interface, forming globular particles that impeded the growth of both α-Al and Al₃Fe phases. With the addition of 0.35&#xa0;wt.% Er, the microstructure, mechanical properties, and electrical conductivity of the alloy were substantially improved. However, increasing Er content to 0.55&#xa0;wt.% resulted in the aggregation of Al₃Er particles, which negatively affected the mechanical properties and conductivity. After annealing at 350&#xa0;°C for 2&#xa0;hours, the 8030-0.35Er alloy exhibited complete recrystallization, forming fine, equiaxed grains with a low dislocation density. As a result, the alloy showed a significant improvement in elongation (34.6%) and electrical conductivity (61.6% IACS), highlighting considerable enhancements in both plastic deformation and electrical performance.</p>