Microstructure and Mechanical Properties of SiC/Mullite Reinforced A356 Composite Foam

The stir casting technique was used to produce A356 alloy composite foams reinforced with different volume fractions of mullite (5, 7.5, 10, and 12.5%) and SiC (5, 7.5, 10, and 12.5%) particles. The microstructure of the fabricated foams reveals a uniform distribution of these particles within the cell walls, as well as good interfacial interaction with the alloy matrix. Compressive stress-strain curves of the composite foam increase smoothly with strain, and there is very marginal stress oscillation occurred in the plateau region of foam throughout the test. It is worth noting that, regardless of foam composition, plateau stress and energy absorption of foams follow power-law relationships with relative density, while densification strain follows a linear trend with relative density. Furthermore, as compared to the SiC particles reinforced composite foams, the mullite reinforcement exhibits higher plateau stress and energy absorption.