Hydriding-dehydriding properties of mg-rich mg-ni-nd alloys with refined microstructures

The hydriding/dehydriding characteristics, pressure-composition isotherms and X-ray diffractographs of Mg-rich Mg-Ni-Nd alloys fabricated by different solidifying processes (mold-casting, water-quenching, or melt-spinning) are compared and discussed in relation with their microstructures observed by SEM. Among them, the alloy prepared by melt-spinning and subsequent annealing presents best hydrogen-storage properties. It can quickly absorb hydrogen up to similar to5.0 mass% above 423 K and can wholly desorb it above 453 K with moderate speeds. These enhanced absorption/desorption kinetics are exclusively caused by a refined microstructure of the alloy involving Mg2Ni and Nd2H5 precipitates in a Mg matrix as well as by a catalytic action of the Nd-hydride.