Phase equilibria in Ir-rich portion of Ir-Al-X (X: V, Nb and Ta) ternary systems

Seiji Miura, Kenji Ohkubo, Yoshihiro Terada, Yoshisato Kimura, Yoshinao Mishima, Yoko Yamabe-Mitarai, Hiroshi Harada, Tetsuo Mohri

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12 Citations (Scopus)


Isotherms of the Ir-rich portion of the Ir-Al-X (X: V, Nb, Ta) systems composed of fcc-Ir solid solution ((Ir)ss), Ir-based L12 intermetallic compounds Ir3X and B2-IrAl are presented as a second report of a series of investigations on the phase equilibria in the (Ir or Rh)-Al-X (X: Ti, Zr and Hf, or, V, Nb and Ta) ternary systems. In both Ir-Al-Nb and Ir-Al-Ta systems fcc/L12/B2 three-phase equilibrium is found. In Ir-Al-V system, Ir solid solution and Ir3V have close compositions each other and fcc/L12/B2 three-phase equilibrium is expected. No ternary compound is observed in all of the isotherms. Solid solubility of each phase is confirmed by chemical analysis by wavelength dispersive X-ray spectroscopy (WDS). The direction of the solubility lobe of L1 2-Ir3X with Al addition is explained in terms of the nearest neighbor interactions. Liquidus surfaces are also established by taking into account the microstructure of as-cast alloys, differential thermal analysis (DTA) data, and the Ir-Al and the Ir-X binary phase diagrams reported previously.

Original languageEnglish
Pages (from-to)263-271
Number of pages9
JournalJournal of Alloys and Compounds
Issue number1-2
Publication statusPublished - 2005 May 31
Externally publishedYes


  • High temperature alloys
  • Intermetallics
  • Scanning electron microscopy

ASJC Scopus subject areas

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


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