Influence of precipitate morphology on the high-temperature deformation of Ir-Nb alloys

Y. Yamabe-Mitarai, H. Harada

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5 Citations (Scopus)

Abstract

The compression strength of an Ir-15at%Nb alloy at 1473 and 2073 K was investigated. A coherent two-phase fee L12 structure was found in the Ir-15Nb alloy. The L12 precipitate morphology depended on the heat treatment. Cuboidal L12 precipitates with a size of 100 nm and a plate-like fee phase inside (type A) were found after heat treatment at 1773 K. The plate-like fee phase disappeared after heat treatment at 2073 K for 24 h, and only a cuboidal L12 phase remained (type B). Coarse rectangular L12 precipitates with a length of 400 nm (type C) were found after heat treatment at 2073 K for 168 h. The influence of L12 precipitate morphology on the high-temperature strength and dislocation structure was investigated after the compression test. A bypass mechanism in which dislocations spread in the narrow fee phase was dominant in the type A and B structures during deformation at 1473 K. In the type C structure, bypassing of precipitates was found to be dominant. At 2073 K, deformation by a shearing mechanism was dominant in the type A and B structures, while deformation by a bypassing mechanism was dominant in the type C structure. When the precipitate size was large and the fee channel width was wide in the type B structure, a bypassing mechanism was dominant. The deformation mechanisms are discussed in terms of the precipitate morphologies.

Original languageEnglish
Pages (from-to)3955-3963
Number of pages9
JournalJournal of Materials Science
Volume38
Issue number19
DOIs
Publication statusPublished - 2003 Oct 1
Externally publishedYes

ASJC Scopus subject areas

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

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