Physical, Corrosion and Microstructural Analysis of A356/SiC Nanocomposites Fabricated through Stir Casting Process

Abstract

Porosity is one of the main difficulty to fabricate the superior quality of aluminium matrix composites (AMCs) because it effects the surface finish of the casting, mechanical properties and corrosion resistance. Therefore, porosity must be minimum as possible so that better casting can be produced with optimal properties of the composites. In this study, aluminium matrix nanocomposites (A356/SiC or AMNCs) were fabricated through two-step stir casting via mechanical alloying using ball mill. The matrix alloy (A356) was reinforced with SiC nanoparticles of 40-55 nm avarage particle size (APS). The corrosion was performed by simple immersion corrosion test method for a predefined environment (3.5% NaCl solution) and for the specified duration. The results showed that density and porosity increase with the addition of reinforcement. The corrosion resistance get reduced with the incorporation of SiC due to the increase in porosity and number of nucleation sites. The substantial correlation between the corrosion rate and the amount of SiC are depicted. Moreover, the corrosion rate decreased with the increase in exposure time which is due to the formation of passive layer. The EDS spectrum shows the presence of different constituents in the composites. The formation of the cracks, oxides, pitting corrosion, and localized corrosion are found by the SEM results. Further, SEM of the corroded surface verifies the presence and good distribution of the SiC nanoparticles in the fabricated nanocomposites.