Hydrogen-storage properties and structure characterization of melt-spun and annealed Mg-Ni-Nd alloy

Abstract

The hydriding/dehydriding characteristics of a Mg-rich Mg-Ni-Nd alloy produced by melt-spinning and subsequent annealing have been investigated. This alloy absorbs ∼ 4.7 mass% hydrogen (H/M ∼ 1.5) quickly between 423 and 573 K and wholly desorbs it at moderate speeds above 453 K. Transmission electron microscope observations and selected-area electron diffraction analyses of this alloy before and after hydriding demonstrate that it consists of multiple phases of Mg2Ni and Nd-hydride precipitated uniformly in a nano-structured Mg matrix. The fast reaction kinetics is caused by an interplay between a catalytic action of the Nd-hydrides and the surrounding nano-sized Mg grains which quickly store or evolve hydrogen across the interfaces.