Dehydrogenation behavior and microstructure evolution of hydrogenated magnesium-nickel-yttrium melt-spun ribbons

This paper reports porous Mg₆₇Ni_33-xY_x (x = 0, 1, 3, 6) ribbons which are prepared by a melt spinning method. The dehydrogenation behaviors, including the thermal decomposition process, dehydrogenation capacities, percentage and kinetics, are investigated in a temperature range of 523-623 K. The microstructure evolution during the dehydrogenation process of metal melt-spun ribbons is discussed with respect to the microstructures of hydrogenated and dehydrogenated ribbons. It is considered that the porous structure in the as-prepared ribbons accelerates the diffusion of hydrogen gas and atoms, and increases dehydrogenation nucleation locations and decreases the diffusion distance. Additionally, the addition of yttrium and melt-spinning decreases the activation energy of dehydrogenation. A low activation energy and a refined microstructure play dominant roles in decreasing the dehydrogenation temperature and increasing the kinetics of Mg-based metal melt-spun ribbons.