<p>Electron beam welding with filler wire was employed to produce dissimilar butt-joints between AA-5083 and AA-5052 sheets under various welding conditions, including different wire feeding speeds and filler wire directions (same direction, reverse direction, and lateral direction). This study presents a comparative analysis of the mechanical properties and microstructure of the aluminum alloy after EB-welding with filler wire. The analysis focused on mechanical properties, including microhardness in the heat-affected zone and weld, tensile strength, and microstructure characteristics in the heat-affected zone and weld. Weld seams produced with forward wire feeding are continuous and uniform, exhibiting good fusion and mechanical properties; however, weld seams formed with reverse and lateral feeding exhibit undercutting, and the weld beads do not properly conform to the surface. An appropriate wire feeding rate resulted in high-quality welds, displaying a straight and uniform shape with clear fish-scale patterns. As the wire feeding speed increases, the mechanical properties of the joints show an increase in tensile strength and a decrease in yield strength. Weld seams formed with filler wire were free from noticeable compositional segregation, cracks, and other defects. However, welds produced at higher speeds exhibited significant internal gas porosity. The weld metal center was composed of fine equiaxed dendrites, and segregation of a large quantity of skeletal Al₃Mg₂ occurred along the grain boundaries. SEM-EDS analysis revealed that the microstructure contained equiaxed second phases, primarily composed of Al-Mn dispersion phases. These phases effectively enhance the tensile strength and hardness of the weld. The FeAl₃ phase was present as an irregular second phase in the microstructure, and clusters of Al₇Cr and Mg₂Si phases may also be present. These irregular phases can easily become a source of performance failure in the structure.</p>