Phase equilibria and stability of Heusler-type aluminides in the NiAl-Ni2AlTi-Ni2AlY (Y: V, Cr or Mn) systems

K. Ishikawa, I. Ohnuma, R. Kainuma, K. Aoki, K. Ishida

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12 Citations (Scopus)

Abstract

Phase equilibria between the B2 and L21 phases and critical boundaries of the B2/L21 continuous ordering in the NiAl-Ni 2AlTi-Ni2AlY (Y: V, Cr or Mn) concentration triangles were determined using diffusion couple technique in the temperature range of 1273-1573K. The B2+L21 two-phase region in the NiAl (B2)-Ni 2AlTi (L21) pseudo-binary section narrows and then disappears due to substitution of the Y element for Ti. The critical temperatures of the B2/L21 ordering at the stoichiometric Ni 2AlY, which were estimated from the experimental data on the basis of the Bragg-Williams-Gorsky approximation, decrease linearly with increasing average of the 3d+4s electron concentration of the elements occupying the Y site. Furthermore, the critical composition boundary of the B2/L21 ordering in the concentration triangle was also well described by the electron concentration of the Y atoms. It can be concluded that the electron concentration of the Y site atoms strongly influences the stability of the Ni2AlY Heusler phase.

Original languageEnglish
Pages (from-to)2-9
Number of pages8
JournalJournal of Alloys and Compounds
Volume367
Issue number1-2
DOIs
Publication statusPublished - 2004 Mar 24

Keywords

  • Heusler alloys
  • Order-disorder transition
  • Phase equilibria
  • Phase stability

ASJC Scopus subject areas

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

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