Abstract
Previous Al4C3 nuclei hypothesis cannot explain the grain refinement mechanism of Mg-Al alloys inoculated by carbon because this nucleant is impossible to form during solidification. In the present investigation a ternary compound Al2MgC2 was identified. It has
a closer crystal structure to Mg than Al4C3. In the centre of grains, one or more “hillocks” with Al, Mn and C-enrichment were observed. A novel grain refinement mechanism is suggested to explain the grain refinement of Mg-Al alloys with carbon inoculations.
