<p>The effect of zirconium (Zr) on the formation of precipitates in the 7075 aluminum alloy was investigated through an aging heat treatment. Four alloys were produced with Zr contents ranging from 0 to 0.355% by weight. The alloys were fabricated using an induction furnace in an open atmosphere, and solidification was carried out in metallic molds. The alloys were characterized in their as-cast condition using optical microscopy (OM), scanning electron microscopy (SEM), and transmission electron microscopy (TEM). Subsequently, a quenching and tempering heat treatment was applied to the alloys according to ASTM B597 (T6), followed by microstructural characterization. Additionally, a modified heat treatment, which included a two-step solution heat treatment process, was evaluated. The microstructure of the base alloy consists of an Al matrix with intermetallic precipitates such as AlSi, Al₂Cu, Al₂MgCu, Mg₂Si, and Al₃Fe. In the as-cast condition, it was observed that Zr promoted microstructural refinement, leading to a 48% reduction in the secondary dendrite arm spacing (SDAS) in alloy A4 containing 0.355&#xa0;wt% Zr, compared to alloy A1 without Zr addition. The alloys containing Zr also exhibited the presence of the Al₃Zr precipitate. After the solution heat treatment, the previously identified phases were retained in both the conventional and modified processes, although they exhibited reduced interconnectivity compared to the as-cast condition. Furthermore, after the aging treatment, nanometer-sized precipitates rich in Al₃Zr and MgZn₂ were identified and uniformly dispersed within the matrix, resulting in a significant increase in the hardness of the alloys.</p>