Effect of SiC particle content on foaming and mechanical properties of remelted and diluted A356/SiC composite

A commercial Al-Si-Mg composite was diluted to different SiC (mean size: 8 µm) contents, and was foamed using TiH2 by melt based technique at a fixed foaming temperature. Foams with high expansions were achieved and uniform cell morphology is obtained at and below 10 vol% SiC. Despite good expansions, certain amount of foam collapse occurs for 5 vol% SiC composite. This work brings out that presence of SiC alone can lead to good foaming but these foams are unstable prior to solidification. This instability can be correlated to in situ oxide content. Both compression and impact (perforation) tests show improved properties with the increase in foam density. Compressive strength is not influenced by SiC content, and energy absorption too seems to be insensitive to the rate of loading within six orders of magnitude.