In situ (Mg2Si+MgO)/Mg composites fabricated from AZ91-Al2(SiO3)3 with assistance of high-energy ultrasonic field

In situ (Mg2Si+MgO)/Mg composites fabricated from AZ91-Al2(SiO3)3 under high-energy ultrasonic field were investigated by XRD, DSC and SEM. The results indicate that the size, morphology and distribution of the in situ Mg2Si particles are greatly optimized with the assistance of the high-energy ultrasonic field. The amounts of the in situ Mg2Si particles are increased, the sizes are refined, the distributions become uniform, and the morphologies are changed to smooth olive-shape or spherical shape. The amounts of brittle β-Mg17Al12 phases are decreased and the morphologies are granulated. The values of the tensile strength σb and HB hardness are increased. These are due to the cavitation effects and acoustic streaming effects induced by the high-energy ultrasonic field.