Synthesis of Nanostructured Mg2Ni for Hydrogen Storage by Mechanical Alloying via High-Pressure Torsion by Edgar Ignacio López Gómez Joaquín Gonzalez Jorge M. Cubero-Sesin & Jacques Huot

Author:Edgar Ignacio López Gómez, Joaquín Gonzalez, Jorge M. Cubero-Sesin & Jacques Huot
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Tags: Mg2Ni is a highly promising candidate for solid-state hydrogen storage due to its high storage capacity. However, its synthesis is challenging due to the high melting point of Ni (1455 C) and the boiling point of Mg (1090 C). In this study, elemental powder mixtures of Mg and 30 at% Ni were processed by high-pressure torsion (HPT) to synthesize the Mg2Ni intermetallic compound through mechanical methods. The formation of 11 wt% of Mg2Ni after 50 turns of HPT was confirmed by X-ray diffraction (XRD), scanning electron microscopy (SEM), and energy-dispersive spectroscopy (EDS), reaching a maximum of 59 wt% after 100 turns. Rietveld refinement confirmed a nanocrystalline size for the Mg2Ni phase synthesized via HPT. Hydrogenation tests showed that the Mg-Ni synthesized by HPT can absorb hydrogen at 350 C even after several weeks of air exposure. Furthermore, a maximum absorption capacity of 3.8 wt% was reached after 20 h of hydrogen exposure for the sample with 100 turns. This capacity is close to the theoretical capacity of 3.9 wt% for this composition. The results confirm that combining HPT with subsequent heat treatment is an efficient strategy to increase the Mg2Ni fraction after HPT processing., severe plastic deformation (SPD); hydrogen storage; metal hydrides; magnesium–nickel intermetallics; nanostructured alloys


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