Microstructural evaluation and mechanical properties of Ir-Hf-Zr ternary alloys at room and high temperatures

J. B. Sha, Y. Yamabe-Mitarai, H. Harada

Research output: Contribution to journalArticle

18 Citations (Scopus)

Abstract

Iridium is one of the most promising base metals for future high-temperature structural materials. Attempts to improve the high-temperature strength of Ir have involved solid-solution hardening and coherent hardening. Hf and Zr having a larger atomic size misfit with Ir were found to be the most effective solid-solution hardening and coherent hardening elements on Ir. The idea of multi-component alloying Ir by Hf and Zr was used for the improvement of high-temperature properties of Ir-based alloys in this work. The results show that the monolithic saturated fcc phase has an outstanding Vickers hardness at room temperature, whereas a dual-phase fcc/L12 structure is favorable for high-temperature strength and creep resistance. With a dual-phase fcc/L12 structure composed mostly of fcc phase, the Ir-5Hf-5Zr alloy has a 0.2% yield strength as high as 175 MPa, and a stable creep rate as low as 1.33 × 10-7 S-1 at a stress of 40 MPa even at 1950 °C. Finally, a principle for the design of Ir-based alloy based upon the composition and microstructural morphology was discussed.

Original languageEnglish
Pages (from-to)1364-1369
Number of pages6
JournalIntermetallics
Volume14
Issue number10-11
DOIs
Publication statusPublished - 2006 Oct 1
Externally publishedYes

Keywords

  • A. Intermetallics
  • B. Microstructure
  • C. Mechanical properties at high temperatures
  • D. Mechanical properties at ambient temperature

ASJC Scopus subject areas

  • Chemistry(all)
  • Mechanics of Materials
  • Mechanical Engineering
  • Metals and Alloys
  • Materials Chemistry

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