Microstructure and mechanical properties of SiC nanoparticles reinforced magnesium matrix composites fabricated by ultrasonic vibration

► SiCp/AZ91 nanocomposite was successfully fabricated by ultrasonic vibration. ► The grains of the alloy matrix in the SiCp/AZ91 nanocomposite are refined. ► The phase Mg 17Al 12 is changed from massive to lamellar in the nanocomposite. ► Tensile strength and elongation of the nanocomposite are simultaneously improved. A particulate reinforced magnesium matrix nanocomposite was fabricated by ultrasonic vibration. Compared with as-cast AZ91 alloy, grain size of matrix in the SiCp/AZ91 nanocomposite decreased and morphology of phase Mg 17Al 12 varied from coarse plates to lamellar precipitates. Although there were still some SiC microclusters in the nanocomposite, most of the SiC nanoparticles were dispersed well outside the microclusters. The ultimate tensile strength, yield strength and elongation to fracture of the SiCp/AZ91 nanocomposite were simultaneously enhanced compared with that of the AZ91 alloy. The study of interface between the SiC nanoparticles and the matrix in the nanocomposite suggested that SiC nanoparticles bonded well with the matrix without interfacial activity.