Chemical diffusion in the iridium-rich A1 and L1 2 phases in the Ir-Nb system

Hiroshi Numakura, Tatsuru Watanabe, Makoto Uchida, Yoko Yamabe-Mitarai, Eisuke Bannai

Research output: Contribution to journalArticlepeer-review

4 Citations (Scopus)


The diffusion in iridium-rich Ir-Nh alloys has been studied by single-phase interdiffusion experiments. The chemical diffusion coefficient has been measured for the primary fee solid-solution and the L1 2 ordered compound Ir 3Nb in the temperature range between 1650 and 1950°C, using Ir/Ir-8Nb and Ir-26Nb/Ir-28Nb diffusion couples, respectively (numbers indicate mol%). While the chemical diffusion coefficient in the solid-solution phase is close to the tracer self-diffusion coefficient of pure iridium, the diffusion in the compound phase is extremely slow: the chemical diffusion coefficient is 1/40 to 1/50 of that in the solid solution. The low diffusion rate in the compound must be beneficial for high-temperature performance of refractory superalloys based on the Ir-Nb system.

Original languageEnglish
Pages (from-to)638-643
Number of pages6
JournalJournal of Phase Equilibria and Diffusion
Issue number6
Publication statusPublished - 2006 Dec


  • Binary interdiffusion
  • Chemical diffusion
  • Intermetallic compound
  • Iridium-niobium alloys
  • Solid-solution

ASJC Scopus subject areas

  • Condensed Matter Physics
  • Metals and Alloys
  • Materials Chemistry


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