Grain Refinement and Mechanism of Mg-3Al Alloy with Fe Element Addition

Grain refinement of Mg-3Al alloy was investigated through adding anhydrous FeCl3 into melts, and the mechanism was discussed. The results show that grains of high-purity Mg-3Al alloy are refined by "native grain refinement", and then markedly coarsened by trace amount of Fe. But when more Fe is added, grains are refined again. Carbon-containing nucleuses are suggested as the main cause to induce "native grain refinement", but they are easily influenced by trace amount of Fe, which can degrade their potence of nucleation, and then grains are coarsened. Grain refinement again is no business with Al-Fe particles, but possibly those nucleuses whose potence of nucleation have been degraded by trace amount of Fe, are changed again by more Fe element into valid ones.