Notable hydriding properties and their origin in a nanostructured Mg2Ni-H system

Shin Ichi Orimo, Hironobu Fujii, Kazutaka Ikeda, Yasuyuki Kitano

Research output: Contribution to journalArticlepeer-review

15 Citations (Scopus)

Abstract

Hydriding and structural properties of a nanostructured Mg2Ni-H system synthesized by reactive mechanical grinding were investigated. The dissolved hydrogen content of the system reached up to 1.6 mass% (Mg2NiH1.8) without changing the crystal structure of an intra-grain region composed of the Mg2NiH0.3 crystallites, and the dehydriding reaction occurred even at 413 K. To clarify an origin of the notable hydriding properties, structural characterizations of the system were carried out. In Mg2Ni-H mechanically ground for 60 min under a hydrogen atmosphere, the HRTEM observation revealed that the sample consists of the equiaxed crystallites with an average size of 15 nm. Moreover, each crystallite is found to be surrounded by the heavily deformed and disordered region nearly 1.5 nm in width. As was evident from the thermal and magnetical analyses, a volume fraction and its hydrogen content of the inter-grain region were around 0.30 and 4.0 mass%, respectively, by the grinding only for 60 min. These results were also supported by the small angle neutron scattering measurements of the nanostructured Mg2Ni-D system. It was concluded that a large amount of hydrogen was dissolved into the disordered inter-grain region. In addition, a cooperative dehydriding reaction between both the intra- and inter-grain regions were discussed as one of the origin for the low-temperature dehydriding around 413 K.

Original languageEnglish
Pages (from-to)685-692
Number of pages8
JournalNippon Kinzoku Gakkaishi/Journal of the Japan Institute of Metals
Volume60
Issue number7
DOIs
Publication statusPublished - 1996 Jul
Externally publishedYes

Keywords

  • Cooperative dehydriding
  • Dissolved hydrogen
  • Hydriding property
  • Inter-grain region
  • Magnesium-nickel
  • Nanostructured material
  • Reactive mechanical grinding
  • Structural property

ASJC Scopus subject areas

  • Condensed Matter Physics
  • Mechanics of Materials
  • Metals and Alloys
  • Materials Chemistry

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