Microstructure and hydrogen sorption properties of Mg–Ni/MmM 5 multi-layer film by magnetron sputtering

Abstract

To improve the hydrogenation properties of Mg–Ni-base alloys, Mg–Ni/MmM 5 multi-layer film was fabricated by magnetron sputtering. The microstructure and hydrogenation properties of as-deposited film were characterized by X-ray diffraction, scanning electron microscopy and pressure-composition isotherm measurement. It was shown that the Mg–Ni layer is composed of preferred orientational nanocrystalline Mg 2Ni and fine-crystalline Mg, while the MmM 5 layer is in amorphous structure. PCI curve of Mg–Ni/MmM 5 multi-layer film at 523 K is composed of two plateaus, which correspond to the hydriding and dehydriding reactions of Mg and Mg 2Ni, respectively; A maximum hydrogen absorption content of 5.0 mass % is obtained at 523 K . The hydrogenation properties of Mg–Ni/MmM 5 multi-layer film are greatly improved than that of the corresponding Mg–Ni alloy target, which is attributed to the nanocrystalline structure of the Mg–Ni layer and catalytic role of the amorphous MmM 5 layer. However, the hydrogenation properties of Mg–Ni/MmM 5 multi-layer film are deteriorated after several cycles.