High temperature strengths of Ir-based refractory superalloys

Y. Yamabe-Mitarai, X. Yu, Y. Gu, Y. Ro, S. Nakazawa, T. Maruko, H. Harada

Research output: Contribution to journalConference articlepeer-review

6 Citations (Scopus)

Abstract

The microstructure and compression strengths of Ir-based binary alloys (Ir-X, where X is V, Ti, Ta, Nb, Hf, or Zr) at temperatures between room temperature and 1800°C were investigated. Several Ir-based alloys displayed superior strength throughout the temperature range. An fcc and L12 two-phase structure was observed in the Ir-based alloys by a transmission electron microscope and is believed to be an important element of the strength performance. Precipitate shape was observed to depend upon the lattice parameter misfit between an fcc matrix and L12 precipitates. Cuboidal L12 precipitates were formed in the Ir-Nb and Ir-Ta alloys with lattice misfit about 0.3%. Plate-like precipitates were formed in the Ir-Hf and Ir-Zr alloys with lattice misfit about 2%, and these precipitates formed a three-dimensional maze structure. Precipitation hardening was investigated in the Ir-Nb and Ir-Zr alloys, but was larger in the Ir-Zr alloy. We observed different deformation mechanisms, shearing mechanism and bypass mechanism in the Ir-Zr and Ir-Nb alloys, respectively.

Original languageEnglish
Pages (from-to)625-632
Number of pages8
JournalKey Engineering Materials
Volume171-174
Publication statusPublished - 2000 Jan 1
Externally publishedYes
EventProceedings of the 1999 8th International Conference on Creep and Fracture of Engineering Materials and Structures - Tsukuba, Jpn
Duration: 1999 Nov 11999 Nov 5

ASJC Scopus subject areas

  • Materials Science(all)
  • Mechanics of Materials
  • Mechanical Engineering

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