Microstructure and tensile properties of micro-SiC particles reinforced magnesium matrix composites produced by semisolid stirring assisted ultrasonic vibration

Magnesium matrix composites reinforced with micro-SiC particles were fabricated by semisolid stirring assisted ultrasonic vibration with SiC particle size of 1 μm and volume fractions of 3% and 5%, respectively. Compared with as-cast AZ91 alloy, with the addition of the micro-SiC particles grain size of matrix was decreased while most of the phase Mg17Al12 varied from coarse plates to lamellar precipitates in 3 vol.% SiCp/AZ91 composite. Although some dispersed micro-SiC particles were found within the grains, most of the micro-SiC particles were located along grain boundaries in both 3 vol.% and 5 vol.% SiCp/AZ91 composites. The study of the interface between the micro-SiC particle and the alloy matrix suggested that micro-SiC particles bonded well with the alloy matrix without interfacial reaction. The ultimate tensile strength and yield strength of the 3 vol.% SiCp/AZ91 composite were improved while elongation to fracture was almost kept.