Protium absorption properties of Mg-Al based ternary alloys

The protium absorption properties of Mg-Al-Cu, Mg-Al-Ni, and Mg-Al-Si alloys have been investigated in conjunction with mi crostructures and the phases present. The alloys were prepared by a flux-melting technique. Mg-Al-Cu as-cast alloys were found to consist of Mg, MgAlCu, and Mg 17 Al 12 phases In addition to the Mg phase, the Mg 17 Al 12 phase also contributed to the protium absorption by undergoing a disproportionation reaction. The protium absorption capacity of these Mg-Al-Cu alloys ranged from 2.2 to 4.6 mass% at 623 K, and was found to be controlled by the amount of Mg and Mg 17 Al 12 phases present. For the Mg-25Al-5Ni and Mg-25Al-5Si as-cast alloys, Mg and Mg 17 Al 12 phases were found to be present. In addition, a Mg 2 Si phase was observed in the Mg-25Al-5Si alloy. The protium absorption capacities of the Mg-25Al-5Ni and Mg-25Al-5Si alloys were 3.6 and 3.9 mass%, respectively, Unlike the Mg-Al-Cu alloys, the Mg 17 Al 12 phase in Mg-Al-Ni and Mg-Al-Si alloys partially remained even after protium absorption. This difference in disproportionation behavior seems to be due to the small amount of solute elements in the Mg 17 Al 12 phase, and/or to the microstructure.