Grain-refining mechanisms of superheat-treatment of and carbon addition to Mg–Al–Zn alloys

Experiments were performed to clarify the grain-refining mechanisms of Mg–Al–Zn alloys by superheat treatment and addition of a new grain refiner. Numerous Al4C3 nucleants were formed in the commercial AZ91E alloy by superheat treatment. Carbon is an important element for grain refining of commercial AZ91E alloy instead of harmful C2Cl6. Numerous Al4C3 nucleants were also formed in the molten alloy.