Mechanical Characteristics of Al-Si Casting Alloys Reinforced with SiC Nanoparticles

Abstract

In this work, composite materials were prepared from aluminum-silicon (Al-Si) alloy (A356) reinforced with silicon carbide (SiC) nanoparticles with different percentage volumetric contents (from 0 to 5 vol.%) using casting method with mechanical stirring. Results of the transmission and scanning electron microscopy (TEM and SEM) showed inhomogeneous distribution of the SiC nanoparticles as dense clusters at high contents, which caused a degradation in the mechanical properties despite the increasing content of the reinforcing material (SiC nanoparticles). The Brinell hardness, yield strength, and ultimate tensile strength (UTS) were determined and compared to the unreinforced fundamental sample (0 vol.% SiC). The enhancement in these properties is attributed to the grain crystallinity with minimum size of 16 μm as well as strengthening mechanisms, whereas the porosity and particle clusters caused the mechanical properties to degrade when the optimum content of the reinforcing material (SiC nanoparticles) is exceeded as the fracture mode converts from completely ductile to a mix of ductile-brittle with dominant brittleness.