Solid state synthesis of non-equilibrium phase in Mg-Co and Mg-Fe systems via bulk mechanical alloying

Tatsuhiko Aizawa, Ken Ichi Hasehira, Chikashi Nishimura

Research output: Contribution to journalArticle

16 Citations (Scopus)

Abstract

Mg-Co and Mg-Fe systems were employed as a candidate hydrogen storage alloy. Different from Mg-Ni system, there exist no line compounds of Mg2Co and Mg2Fe. Non-equilibration of these compounds is indispensable to make solid state synthesis. Bulk mechanical alloying was applied to this non-equilibration of Mg2Co with success. Planetary ball milling was also utilized to discuss the process efficiency of bulk mechanical alloying. In particular, the on-line monitored energy density was used to describe the homogeneous refining and solid-state reaction with increasing the number of cycles. Through SEM observation of intermediate phase change, the solid-state reaction commences when the total energy density exceeds the critical limit. SEM/EDX and XRD analyses assured that the synthesized non-equilibrium phase should be Mg2Co. The Goldschmidt-factor analysis was used to determine that the synthesized Mg2Co has mainly fcc-structure. No significant change of XRD profiles was observed even when increasing the holding temperature. This Mg2Co is quasi-stable, non-equilibrium phase even at the elevated temperature. In case of Mg-Fe system, the initial elemental particle mixture was homogeneously refined. Under the similar condition to the solid-state synthesis of Mg2Co, however, Mg2Fe was not synthesized even via bulk mechanical alloying. Through precise analysis, non-equilibrium phase with high iron content was recognized, so that non-equilibration via the bulk mechanical alloying might well be effective to investigate the solid state synthesis of binary compounds even in Mg-Fe system.

Original languageEnglish
Pages (from-to)601-610
Number of pages10
JournalMaterials Transactions
Volume44
Issue number4
Publication statusPublished - 2003 Apr
Externally publishedYes

Fingerprint

Mechanical alloying
alloying
solid state
synthesis
Solid state reactions
Hydrogen storage alloys
flux density
Scanning electron microscopy
Ball milling
Factor analysis
scanning electron microscopy
factor analysis
Refining
refining
Energy dispersive spectroscopy
Iron
balls
Temperature
iron
cycles

Keywords

  • Bulk mechanical alloying
  • Hydrogen absorption
  • Mg-Co
  • Mg-Fe
  • MgCo
  • Non-equilibrium
  • Solid-state synthesis

ASJC Scopus subject areas

  • Materials Science(all)
  • Metals and Alloys

Cite this

Solid state synthesis of non-equilibrium phase in Mg-Co and Mg-Fe systems via bulk mechanical alloying. / Aizawa, Tatsuhiko; Hasehira, Ken Ichi; Nishimura, Chikashi.

In: Materials Transactions, Vol. 44, No. 4, 04.2003, p. 601-610.

Research output: Contribution to journalArticle

Aizawa, Tatsuhiko ; Hasehira, Ken Ichi ; Nishimura, Chikashi. / Solid state synthesis of non-equilibrium phase in Mg-Co and Mg-Fe systems via bulk mechanical alloying. In: Materials Transactions. 2003 ; Vol. 44, No. 4. pp. 601-610.
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