Microstructural characterization and hydrogenation study of extruded MgFe alloy

G. F. Lima, M. M. Peres, S. Garroni, M. D. Baró, C. S. Kiminami, T. T. Ishikawa, W. J. Botta, A. M. Jorge, Santiago Suriñach Cornet

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13 Citations (Scopus)

Abstract

Mg-based nanocrystalline alloys or nanocomposites are promising materials for hydrogen storage in the solid state, which is a more effective and safer storage medium than pressurized or liquefied hydrogen. Among the many Mg-based hydrides of interest for hydrogen storage, Mg2FeH6 is in a special position due to its relatively high gravimetric capacity of 5.5% and excellent volumetric density of 150 kg H2/m3. This work involved a study of the synthesis and processing of Mg-based alloys of this type, produced by high-energy ball milling and hot extrusion. A mixture of 2Mg-Fe was prepared by high-energy ball milling under argon gas. The resulting powder was cold-pressed to produce cylindrical pre-forms, which were then extruded and the sorption properties were analyzed in a microbalance and in a Sieverts apparatus. Phase formation, microstructural evolution, desorption temperatures, and hydrogen storage capacity were analyzed by X-ray diffraction, scanning electron microscopy (SEM), differential scanning calorimetry, and thermogravimetric techniques. The results showed that Mg2FeH 6 was formed and the hydrogen reaction was reversible. SEM observations indicate a microstructure composed of nanosized grains in the range of 30-80 nm inside particles of about 50 μm, and Mg2FeH 6 formed mainly at the particle interfaces. The desorption temperature started at about 225 °C, reaching a maximum at 440 °C with low capacity of absorption, indicating low absorption/desorption kinetics, probably due to bulk diffusion limitations. © 2010 Elsevier B.V.
Original languageEnglish
JournalJournal of Alloys and Compounds
Volume504
DOIs
Publication statusPublished - 1 Aug 2010

Keywords

  • Complex hydrides
  • Hot extrusion
  • Hydrogenation process
  • Mg alloy

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