Effect of SiC particle addition on microstructure of Mg2Si/Al composite

• Main Authors: Zhao Yuguang, Liu Xiaobo, Yang Yuanyuan
• Format: Article
• Language: English
• Published: Foundry Journal Agency 2014-03-01
• Series: China Foundry
• Subjects: Mg2Si/Al matrix composite; SiC particles; microstructure; solidification
• Online Access: http://www.foundryworld.com/uploadfile/2014041053656429.pdf

In the present study, by adding SiC particles into Al-Si-Mg melt, Mg2Si and SiC particles hybrid reinforced Al matrix composites were fabricated through the Mg2Si in situ synthesis in melt combined with the SiC ex situ stir casting. The as-cast microstructure containing primary Mg2Si and SiC particles that distribute homogenously in Al matrix was successfully achieved. The effects of SiC particle addition on the microstructure of Mg2Si/Al composites were investigated by using scanning electron microscopy (SEM) and XRD. The results show that, with increasing the fraction of the SiC particles from 5wt.% to 10wt.%, the morphologies of the primary Mg2Si particulates in the prepared samples remain polygonal, but the size of the primary phase decreases slightly. However, when the SiC particle addition reaches 15wt.%, the morphologies of the primary Mg2Si particulates change partially from polygonal to quadrangular with a decrease in size from 50 μm to 30 μm. The size of primary Al dendrites decreases with increasing fraction of the SiC particles from 0wt.% to 15wt.%. The morphology of the eutectic Mg2Si phase changes from a fiber-form to a short fiber-form and/or a dot-like shape with increasing fraction of the SiC particles. Furthermore, no significant change in dendrite arm spacing (DAS) was observed in the presence of SiC particles.