Creep of face-centered-cubic {111} and {100} grains in FeCoNiCrMn and FeCoNiCrMn–Al alloys: Orientation and solid solution effects

M. T. Tsai, J. C. Huang, P. H. Lin, T. Y. Liu, Y. C. Liao, Jason S.C. Jang, S. X. Song, T. G. Nieh

Research output: Contribution to journalArticlepeer-review

9 Scopus citations

Abstract

In this study, creep behavior of the face-centered-cubic (FCC) {111} and {100} grains in single-phase Fe20Co20Ni20Cr20Mn20 and dual-phase Fe18Co18Ni20Cr18Mn18Al8 high-entropy alloys (HEAs) was evaluated using a nanoindentation method over temperatures range of 300–600 °C. We measured the creep response of the two different grain orientations in the two alloys in order to study the orientation and solid-solution effects. Creep stress exponent (∼3.8–5.0) and activation energy (240–260 kJ/mol) were extracted and analyzed from stain rate-stress and stain rate-temperature data to provide information on the creep mechanism. The results indicated that creep was controlled by dislocation climb in both alloys at both orientations. However, we pointed out that, based upon activation energy value alone, it was difficult to identify which elemental constituent would be the dominant diffusing species responsible for vacancy diffusion during the climb. It was found that creep activation volume for the current two HEAs (140 Å3 or ∼12Ω where Ω is the atomic volume) at 600 °C is larger than that reported for the Ni-based superalloys (∼50–100 Å3 or less) within a similar temperature range. The significance of this larger activation volume is also discussed.

Original languageEnglish
Pages (from-to)88-96
Number of pages9
JournalIntermetallics
Volume103
DOIs
StatePublished - Dec 2018

Keywords

  • Activation energy
  • Activation volume
  • Creep
  • High entropy alloy
  • Nanoindentation

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