Hydrogen absorption and desorption by Mg67-xCa xNi33 powders prepared by mechanical alloying

Akito Takasaki, Kazuya Sasao

研究成果: Article

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Mg67-xCaxNi33 elemental powder (0≤x≤20) mixtures were mechanically alloyed by a planetary ball mill, and phase variations after mechanical alloying (MA) and subsequent hydrogenation by gas phase loading at temperatures of 373 and 503 K, and their hydrogen desorption were investigated. The MA leaded to the formation of the Mg 2Ni-type phase for all powders. All powders containing Ca were induced to form an amorphous-like phase after hydrogenation at 373 K for 168 h, although the binary Mg67Ni33 powder was the α-phase (Mg2NiH0.3 hydride). After hydrogenation at 503 K, on the other hand, the low temperature (LT)-phase (Mg2NiH4 hydride) formed for all powders. The ternary powders also formed the CaH 2 hydrides. The temperature for the maximum hydrogen desorption rate increased with increasing Ca concentration in the powders after hydrogenation at both temperatures. The activation energies for hydrogen desorption for the binary powder after hydrogenation at 373 and 503 K were the same, about 92 J mol-1, and those for Mg47Ni33Ca20 powder at 373 and 503 K were about 168 and 244 J mol-1, respectively, indicating that substitution of Ca for Mg stabilized the hydrides.

元の言語English
ページ(範囲)431-434
ページ数4
ジャーナルJournal of Alloys and Compounds
404-406
発行部数SPEC. ISS.
DOI
出版物ステータスPublished - 2005 12 8

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ASJC Scopus subject areas

  • Mechanics of Materials
  • Mechanical Engineering
  • Metals and Alloys
  • Materials Chemistry

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