Effect of Minor Elements on Grain Size of Mg-9%Al Alloy

The Influence of minor elements, such as Be. Zr, Fe and Mn. on grain size and grain-refining effect of Mg-9%Al alloy was investigated by use of high-purity Mg-9%Al alloy (high-purity alloy). This high-purity alloy was prepared from distilled pure magnesium and 99.99% commercial aluminum. Given amounts of Be. Zr, Fe and Mn were then added Microscopic examination clarified that these elements have grain coarsening action for natural fine-grained high-purity alloys, and the grain refinement by superheating was possible as long as the alloy grain was coarsened by Fe or Mn addition EPMA analysis revealed the existence of some species of aluminum carbide in high-purity alloy Fe-Al-C-O and Mn-Al-C-O compounds were also obscrved in allovs coarsc-grained by Fe or Mn addition Existence of aluminum carbide and its change were probably associated with the grain size of the Mg-9%Al alloy.