Protium absorption properties of Mg-Al based ternary alloys

The protium absorption properties of Mg-AI-Cu, Mg-Al-Ni, and Mg-Al-Si alloy s have been investigated in conjunction with microstructures 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 Mg17Al12 phases. In a ddition to the Mg phase, the Mg17Al12 phase also contributed to the protium absorption by undergoing a disproportionation reaction. The protium absorp tion capacity of these Mg-AI-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 Mg17Al12 phases p resent. For the Mg-25Al-5Ni and Mg-25Al-5Si as-cast alloys, Me and Mg17Al12 phases were found to be present. In addition. a Mg2Si phase was observed i n the Mg-25Al-5Si alloy. The protium absorption capacities of the Mg-25Al-5 Ni and Mg-25Al-5Si alloys were 3.6 and 3.9 mass%: respectively. Unlike the Mg-Al-Cu alloys, the Mg17Al12 phase in Mg-Al-Ni and Mg-Al-Si alloys partial ly remained even after protium absorption. This difference in disproportion ation behavior seems to be due to the small amount of solute elements in th e Mg17Al12 phase, and/or to the microstructure.