Microstructure and hydrogen storage properties of Mg1.8Y0.2Ni1−yCoy (y = 0, 0.05, 0.1, 0.15, 0.2) alloys

Abstract

The Mg1.8Y0.2Ni1−yCoy (y = 0, 0.05, 0.1, 0.15, 0.2) hydrogen storage alloys were prepared following the principles of metallurgy, the phase composition and microstructure of the alloys were studied using XRD and SEM/EDS techniques, and the hydrogen absorption and desorption properties of the alloys were studied using PCT and DSC techniques. The results showed that the addition of Co did not affect the phase composition of Mg1.8Y0.2Ni1−yCoy alloys in the as-cast state and after hydrogen absorption. The Co addition could help refine the microstructure of the alloys to a certain extent. The de-/hydrogenation kinetics of Mg1.8Y0.2Ni1−yCoy (y = 0, 0.1, and 0.2) alloys were improved by adding Co, and the best results were obtained at y = 0.1. The onset decomposition temperature of Mg1.8Y0.2Ni1−yCoy (y = 0, 0.1, and 0.2) alloys were recorded to be 180 °C, 156 °C, and 210 °C, respectively, which were significantly lower than that of Mg2Ni (253 °C). The results revealed that the addition Co could improve the thermodynamic performance of the dehydrogenation process.