Grain refinement of Mg-Al cast alloy by the addition of manganese carbonate

摘要

The effect of MnCO_3 addition on grain refinement of Mg-Al alloys was investigated. The microstructural changes induced by MnCO_3 addition indicate that it has excellent grain refining efficiency for Mg-9 wt.%Al alloy. In addition the average grain size was reduced from 480 to 61 mu m by 0.6 wt.% addition. This is attributed to inoculation of MnCO_3, which brings about the formation of potent heterogeneous nucleants such as MgO, Al_4C_3, and Al_8Mn_5 before solidification of alpha-Mg as well as melt agitation by the release of CO_2 gas.