Abstract:A novel Al-Ti-C master alloy containing Al₄C₃ and TiC particle clusters, which exhibits great refining potential for Mg, was prepared. With the addition of 2% Al-Ti-C master alloy, the grains transform to equiaxed crystal with a diameter of (110±17) μm. The results indicate that Al₄C₃ and TiC particle cluster, rather than a single particle, plays an important role in the refining process. Compared with the simplex smooth nucleating substrate, concave regions on the particle cluster provide easier route for the transformation from liquid Mg atoms to stable nucleus. Nucleus with a small size can also reach the critical nucleation radius when they attach on the concave regions of the substrate. Al₄C₃ and TiC particle clusters thus become more favorable nucleating substrate for α-Mg grains.

Key words: Mg; Al-Ti-C master alloy; particle cluster; grain refinement