Hydrogen-Storage Properties of Nanocrystalline Mg-Based Materials Created through Controlled Devitrification of a Metallic Glass

Abstract:

Mg-based nanostructured materials with a composition of Mg₈₅Ni_15-xM_x (M=Y, La, or Pd) have been fabricated by proper alloying additions and controlling the crystallization process of melt spun metallic glass ribbon. XRD suggests that the average crystallite sizes range from 100 nm in the binary materials to <30 nm in the ternary alloys. Hydrogen absorption/desorption measurements show improved properties compared to nanocrystalline alloys fabricated using other processing strategies. Surface treatment of the binary and Pd-containing ribbons by ball milling or submersion in aqueous NH₄⁺ allows the materials to be activated at 473 K, significantly lower than conventional Mg-based hydrogen storage materials. Y and La additions improve the maximum storage capacity. Absorption kinetics are also improved the materials is alloyed with La, while Y slows the reaction kinetics. Some degradation in storage capacity is observed when the materials are exposed to a cyclic absorption/desorption process, likely due to microstructural coarsening. The Mg₈₅Ni₁₀Pd₅ composition fully absorbs and desorbs ≈5 wt. % H at 473 K, while other bulk Mg-based materials require temperatures in excess of 573 K.

• Periodical: Solid State Phenomena (Volumes 172-174)
• Pages: 947-952
• DOI: https://doi.org/10.4028/www.scientific.net/SSP.172-174.947
• Online since: June 2011
• Authors: Eric A. Lass
• Keywords: Hydrogen Storage, La-Mg Based Alloy, Metal Hydride, Metallic Glass, Nanostructured Materials

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