Effects of Manganese and/or Carbon on the Grain Refinement of Mg-3Al Alloy

Abstract

The effects of manganese and/or carbon on the grain refinement of Mg-3Al alloy have been investigated in the present study. Significant grain refinement was obtained for the Mg-3Al alloy modified with either carbon or Al-Mn master alloy. There existed an optimal content of 0.1∼0.2 mass%Mn to obtain refining grain size for the Mg-3Al alloy. The Al-Mn intermetallic particles with molar ratio of 1:1 were considered as potent nuclei for Mg grains. The addition of Mn had no obvious effect on the grain size for the Mg-3Al alloy which was refined by 0.2 mass%C. The Al-C-O-Mn compounds were considered as the potent nuclei for Mg grains. A new hypothesis that the particles of Al-Mn compounds with Al₄C₃ coating film can act as potent nuclei for Mg grains was proposed.