Grain Size and Porosity of Silicon Carbide Nanoparticles-Reinforced Aluminum-Silicon Casting Alloys

Abstract

This letter introduces experimental results on the effects of reinforcement of Al-Si casting alloys with different volumetric percentages of SiC nanoparticles on average grain size and porosity of these alloys. The alloy samples were prepared by conventional casting with mechanical mixing and ultrasonic waves to ensure homogeneous distribution of the nanoparticles. Adding up to 2 vol.% SiC nanoparticles lead to reasonable enhancement in grain crystallization as the average grain size was reduced from 48μm for the unreinforced sample to a minimum of 17μm. This is attributed to the role of nanoparticles as heterogeneous nucleation sites in the alloy structure. On the other hand, increasing the content of nanoparticles lead to increase the porosity from minimum of 0.5 vol.% to a maximum of 2.6 vol.% at 10 vol.% nanoparticles. This is attributed to the increase in molten viscosity as well as trapped gases during resolidification.