Tensile creep behavior of single-crystal high-entropy superalloy at intermediate temperature

Takuma Saito, Akira Ishida, Michinari Yuyama, Yuji Takata, Kyoko Kawagishi, An Chou Yeh, Hideyuki Murakami

Research output: Contribution to journalArticlepeer-review

Abstract

In this study, we investigated the creep deformation mechanism of a single-crystal highentropy superalloy (HESA) with the spherical 0 precipitates at 760 °C. Before the creep tests, long-term aging tests at 760 °C without load were conducted, which showed Ostwald ripening of the secondary 0 precipitates up to 50 h. The creep tests revealed that in the range of 500 and 600 MPa at 760 °C, the creep deformation mechanism of HESA was independent of applied stress in both the primary and secondary creep regions. The deformation mechanism of HESA was further investigated under the condition of 760 °C and 520 MPa by performing creep interrupted tests and microstructural analysis. Scanning electron microscope observation showed elongated 0 precipitates along the applied stress axis near the ruptured surface. This could have been caused by the multi-slip around <100> preceded by the lattice rotation into <100> along the tensile axis, which was confirmed by the electron backscatter diffraction analysis. Transmission electron microscope observation of the creep interrupted and ruptured specimens showed bypass and climb motion of dislocations in the 2-h interrupted, shearing of the 0 precipitates by the paired straight dislocations in the 50-h interrupted, and shearing of the 0 precipitates by both the straight and the curved paired dislocations in the ruptured specimens, respectively. The secondary 0 precipitates do not affect creep behavior as long as the deformation mechanism is a bypass and climb motion of dislocations.

Original languageEnglish
Pages (from-to)1-17
Number of pages17
JournalCrystals
Volume11
Issue number1
DOIs
Publication statusPublished - 2021 Jan 1

Keywords

  • Creep
  • Dislocation
  • High entropy
  • Superalloys

ASJC Scopus subject areas

  • Chemical Engineering(all)
  • Materials Science(all)
  • Condensed Matter Physics
  • Inorganic Chemistry

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