<p>The present investigation evaluates the influence of 5 wt.% silicon carbide (SiC) addition on the microstructural and mechanical behavior of a hypereutectic Zn–18 wt.% Al–1.5 wt.% Cu alloy. The Zn–18 wt.% Al–1.5 wt.% Cu/5 wt.% SiC composite was produced using stir casting. Optical microscopy (OM) and scanning electron microscopy (SEM) observations revealed that both the base alloy and composite consist of η–Zn–rich, α–Al–rich, β–ZnAl eutectic dendrites, and ε–CuZn₄ phases. X-ray diffraction (XRD) results demonstrated substantial crystallite refinement in the composite: the η–Zn phase decreased from 267 to 144 Å, while the α–Al and β–ZnAl phases increased from 324 to 441 Å. Lattice parameters slightly expanded for all phases (η–Zn: a = b = 2.68 Å, c = 4.90 Å; α–Al: a = b = c = 4.45 Å; β–ZnAl: a = b = c = 4.45 Å), accompanied by increased dislocation densities (η–Zn: 1.40×10⁻⁵ Å⁻² → 4.82×10^-5 Å⁻²) and microstrain (η–Zn: 0.0038% → 0.0072%), confirming lattice distortion and effective load transfer from the matrix to the SiC particles. Hardness measurements showed a clear improvement, with the composite reaching 165 Hv at 75 °C compared with 120 Hv for the base alloy. This strengthening is attributed to microstructural refinement, higher dislocation density, and effective load transfer from the matrix to the SiC particles, substantially enhancing the mechanical performance of the Zn–18 wt.% Al–1.5 wt.% Cu alloy. These findings establish Zn–18 wt.% Al–1.5 wt.% Cu/5 wt.% SiC composite as promising candidate for high strength, wear resistant applications.</p> Graphical Abstract <p></p>