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 Mg 2 Ni 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.

Hydriding-Dehydriding Properties of Mg-Rich Mg-Ni-Nd Alloys with Refined Microstructures

“…In this sample, Mg 2 Ni particles (bright spots) of ∼0.3 µm in size are homogeneously distributed in the Mg matrix (gray region). An elaborate high-resolution transmission electron microscope (HRTEM) observation of this sample 11) indicates that it consists of Mg 2 Ni and Mg 12 Nd particles of 0.2-1.0 µm and ∼30 nm in diameter, respectively, precipitated in a Mg matrix with ultrafine grains of ∼5 nm. The MS sample has therefore been confirmed to have a much finer microstructure than those of the AC and WQ samples.…”

“…We have also suggested that a catalytic effect of Nd-hydrides is quite important for the enhancement, and discussed its mechanism in a separate paper. 11) In addition to these two factors that influence the reaction kinetics, the degree of refinement of the microstructure is considered to be another important factor at least for the desorption process. This is really proved by examining the H/D kinetics of the MS sample as shown below.…”

Electrochemical hydrogen storage properties of ball-milled NdMg12 alloy with Ni powders

“…Incorporation of Nd in the Mg-based alloy for hydrogen storage has been attempted. It was reported that Mg-rich Nd-Mg or Mg-Ni-Nd alloys can absorb hydrogen up to 4.7 mass% above 423 K and completely desorb it above 453 K [15,16]. However, up to the knowledge of the authors, characteristics of the NdMg 12 alloy for electrochemical hydrogen storage have not been reported before.…”

Determination and interpretation of the hydriding and dehydriding kinetics in mechanically alloyed LaNiMg17 composite

“…Owing to the excellent catalysis of the lanthanide series, a comparative study of the influence of the additive RE (RE = La, Y, Nd and Mm) on the H/D properties was carried out by Spassov et al [9][10][11], they reported that Mg 75 Ni 20 Mm 5 (Mm = Ce, La-rich mischmetal) alloy can absorb 4.0 mass% H in 115 min at 298 K. Cai et al [12] found that the as-cast La 1.8 Ca 0.2 Mg 16 Ni ingot can reach 4.9 mass% H at 573 K under 3MPa but its dehydriding kinetics was rather poor. Yin et al [13] claimed that the Mg 86 Ni 10 Nd 4 alloy can absorb and desorb more than 4.5 mass% H at moderate speeds above 453 K. Although much attention was paid to the properties of the Mg-Ni-RE alloys as mentioned above, few studies on the H/D kinetic mechanism of these alloys have been carried out. It is important to clarify the kinetic mechanism for practical application of any new hydrogen storage alloys.…”