Abstract:Coarse and agglomerated primary Mg₂Si phase in in-situ synthesized Mg₂Si/Mg composite with 4%Si was treated in remelting process by means of high intensity ultrasonic vibration. The effects of ultrasonic vibration duration and temperature on size, morphology and distribution of the primary Mg₂Si were studied. The evolution mechanism was discussed. The microstructures of the composites were investigated by means of optical microscopy (OM) and scanning electronic microscopy (SEM). The components were inspected with energy dispersion spectrum (EDS) and X-ray diffraction (XRD). The results indicate that ultrasonic vibration does not alter two constituents of the composites, but changes the size and distribution of aggregated primary Mg₂Si particles. The size of primary Mg₂Si particles decreases with the increase of vibration duration and vibrating temperature. High intensity ultrasonic has little effects on the primary Mg₂Si morphology. The high intensity ultrasonic vibration is an effective means to prepare well-proportioned in-situ synthesized magnesium matrix composites.

Key words: Mg₂Si/Mg composite; high intensity ultrasonic vibration; in-situ synthesis; microstructure; primary Mg₂Si