Casting A356+SiCp with ultrasonically treated melts Effect reinforcement and processing in the microstructure

Abstract

Low mass fractions (0.05 wt%) of SiC micro sized particles have been added to an A356 melt and dispersed by ultrasonic vibration to study their impact on the microstructural morphology of cast samples. It is shown that the ultrasonic melt treatment at 680°C can promote a homogenized distribution of the reinforcement while also degassing the melt and induces a moderate grain refinement. Even though SiC may act as a nucleant, its use did not induce a significant grain refinement relatively to ultrasonically treated unreinforced melts. Adding SiC microparticles, however, seems to enhance Eutectic Si modification, although it contributes to its slight coarsening at the expense of Mg₂Si.