Functional Evaluation of the Effect of ZrO₂ Reinforcements on the Density, Microstructure, Strength and Hardness of Al–12 wt%Si Alloy Based Composites

The present study investigates the impact of ZrO₂ inoculants on the morphology and properties of stir-cast Al–12Si/ZrO₂ metal matrix composites (MMCs). Composites with varying ZrO₂ weight percentages (0.5, 1, and 3%) were fabricated, and microstructural analyses were conducted using optical microscopy (OM) and scanning electron microscopy (SEM) with energy dispersive X-Ray analysis (EDAX). ASTM standards were followed for sample preparation and testing. For the Al–12%Si base alloy, density ranged from 2.695 to 2.699 g/cm³. Micro hardness varied from 43.80 to 49.10 HV, and ultimate tensile strength ranged from 275.2 to 324.1 MPa with changing ZrO₂ content. Yield strength followed a similar trend, with Al–12 wt%Si reinforced with 3 wt% ZrO₂ displaying the highest at 257.8 MPa and as-cast Al–12 wt% base alloy having the lowest at 232.9 MPa. These variations are attributed to the micro-coring effect of ZrO₂ particulates in the Al–12 wt%Si matrix. The study establishes a clear relationship between ZrO₂ content, composite morphology, and resulting properties, offering valuable insights for potential engineering applications.