Preparation and theoretic study of semi-solid Al₂Y/AZ91 magnesium matrix composites slurry by ultrasonic vibration

黄文先^1,2,3，闫洪^1,2

1. Department of Materials Processing Engineering, School of Mechanical Electrical Engineering, Nanchang University3. Department of Civil Engineering, School of Architectural Engineering,Jinggangshan University

摘 要：Semi-solid Al2Y/AZ91 magnesium matrix composites slurry was prepared by ultrasonic vibration, effect of ultrasonic vibration temperature and time on microstructure of semi-solid slurry was investigated. The results showed that with the ultrasonic vibration temperature decreasing the solid volume fraction of semi-solid slurry increased. The best ultrasonic vibration temperature was 600 oC. With the increase of ultrasonic vibration time, the average grain diameter of primary а-Mg particles decreased firstly, then increased, the average shape factor increased gradually and decreased slightly after 90 s, and a few rosette dendrites were observed after 120 s. The best semi-solid slurry with average grain diameter of 75 μm and shape factor of 0.7 were gained after the melt was treated by ultrasonic vibration for about 60 s at near liquidus temperature（600 oC）. At last, the microstructure evolution mechanism of semi-solid magnesium matrix composites slurry was analyzed by the theories of thermodynamics and kinetics.

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