Characterization of SiC-Reinforced AZ91 Magnesium Alloy Composites Produced Using In situ Microwave Casting

Magnesium-alloys-based metal matrix composites (MMCs) are one of the most researched materials for producing industrial components due to their high specific strength. In recent years, microwave energy has been used for processing of various materials including polymers, ceramics, metals, and composites owing to significant saving of energy and time as compared to the conventional processes. In the present work, microwave energy at 2.45 GHz was used to fabricate AZ91 magnesium-alloy-based MMCs. The AZ91 magnesium alloy (bulk) pieces were hybrid heated inside a microwave applicator at 1400 W. The melt was processed with silicon carbide (SiC) and allowed to pour into a graphite mold. The produced composites were characterized to study their microstructural properties. The microstructural characterization of the composites revealed that distribution of SiC particles is uniform. Finer grains were achieved in the composite as compared to as-received alloy. The presence of SiC, Mg2Si, Mg2C, Mg2C3, Mg17(Al, Zn)12, and α-Mg phases was confirmed in the composite through energy-dispersive X-ray spectroscopy analysis. The micro-indentation hardness of the composite was found as 206 ± 28 HV which is higher than as received alloy.