AM60B alloy has been refined by SiC particles and the corresponding refining mechanism has been mainly discussed. The results indicate that the addition of 0.2 wt% SiC particles in form of mixture with Mg powder decreases the grain size from 317 μm of the not refined alloy to 46 μm. The decrease of β phase and formation of Mg_2Si and Al_4C _3 phases well demonstrate that the reactions of 3SiC + 4Al = Al _4C_3 + 3Si and 2Si + Mg = Mg_2Si occur during refining treatment. In addition, the crystal nuclei are composed of two kinds of elements, Al and C. All of these imply that the formed Al_4C _3 particles are the actual heterogeneous nucleation substrates.
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