Preparation and protium absorbing properties of Mg-based ternary alloys

The protium absorbing properties of Mg-Y-Ni, Mg-Y-Cu, and Mg-Al-Cu ternary alloys have been investigated in conjunction with phases present and microstructures. The alloys with a Mg-rich composition (≈80 at%Mg) were prepared by a flux-melting technique. It was found that the Mg-10Y-10Ni alloy with Mg, Mg₂₄Y₅, Mg₂Ni, and MgNi₂ (C15-type Laves structure) phases formed hydrides of Mg₂Ni and Mg at 373 and 473 K, respectively. The decrease in the reaction temperature can be attributed to a morphological improvement, where Mg and Mg₂₄ Y₅ main phases with a needle-like shape surrounded by the Mg₂Ni and MgNi₂ phases, and/or the effect of Y incorporated into these phases. The Mg-10Y-10Ni alloy absorbed 4.O and 4.5 mass% of protium at 473 and 573 K, respectively. For the Mg-10Y-10Cu alloy, a two-step plateau regime was observed due to the disproportionation of the Mg₂Cu phase. The Mg-6Y-24Cu alloys exhibited a protium storage capacity of 3.4 mass%, and its plateau pressure for the desorption process was about 0.08 MPa at 523 K. The Mg-10Al-10Cu alloy absorbed 4.5 mass% of protium. However, a temperature as high as 573 K was needed for observing the protium absorption -desorption process.