Microstructure and mechanical properties of SiCp/MgZnCa composites fabricated by stir casting

SiCp/Mg. Zn. Ca composites with three volume fractions (5%, 10% and 15%) were successfully fabricated by stir casting. The particle distributions were fairly uniform in all composites, although most particles were segregated along grain boundaries in the micro-scale level. Interfacial reaction products were not observed at the interface between SiCp and matrix. SiCp affected the size and shape of the second phases as well as their distribution in the matrix. In the 5% composite, many large second phases were observed at the particle surfaces. As the particle content was increased up to 10%, large second phases were hardly observed at the SiCp surfaces. Moreover, the second phases mainly existed in the form of fine flake in the 10% and 15% composite, unlike the alloy and 5% composite in which the second phases were large. The effect of SiCp on the second phases significantly influenced the mechanical properties of the composites. Compared with the matrix alloy, 15% composites had good room temperature and high temperature mechanical properties.