Phase separation and stability of L21-type phase in Co 2(Cr1-xFex)(Ga1-yAly) alloys

Kosei Kobayashi, Ryosuke Kainuma, Kiyohito Ishida

Research output: Contribution to journalArticlepeer-review

12 Citations (Scopus)

Abstract

The B2/L21 order-disorder transition and ferromagnetic/ paramagnetic transition temperatures in Co2(Cr1-xFe x)(Ga1-yAly) alloys were determined by differential scanning calorimetry and transmission electron microscopy. It was found that spinodal decomposition cannot be suppressed by quenching in the Al-rich portion of Co2Cr(Ga1-yAly) alloys, leading to lowering of Curie temperature Tc. The transition temperature TtB2/L21 from the B2 to L21-type phase decrease with increasing y for both the Co2Cr(Ga 1-yAly) and Co2Fe(Ga1-yAl y) alloy systems. The Tc in the Ga-rich portion of the L21-type Co2Cr(Ga1-yAly) alloy system is almost constant at about 480K, whereas that in the B2-type Co 2Fe(Ga1-yAly) alloy system slightly increases from about 1100 K to about 1170K. By extrapolation from the Ga-rich side of Co2Cr(Ga1-yAly) alloys, Tt B2/L21 and Tc of the metastable Co2CrAl alloy were determined as 800 and 470 K, respectively. An optimal concentration area for obtaining excellent half-metallic properties and high stability of the L21-type phase in the Co2(Cr1-xFe x)(Ga1-yAly) alloys is proposed.

Original languageEnglish
Pages (from-to)20-24
Number of pages5
JournalMaterials Transactions
Volume47
Issue number1
DOIs
Publication statusPublished - 2006 Jan

Keywords

  • Cobalt-chromium-iron-gallium-aluminum
  • Half-metallic ferromagnets
  • L2-type phase
  • Order-disorder transition
  • Spinodal decomposition

ASJC Scopus subject areas

  • Materials Science(all)
  • Condensed Matter Physics
  • Mechanics of Materials
  • Mechanical Engineering

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