Outstanding tensile properties of a precipitation-strengthened FeCoNiCrTi0.2 high-entropy alloy at room and cryogenic temperatures

Y. Tong, D. Chen, B. Han, J. Wang, R. Feng, T. Yang, C. Zhao, Y. L. Zhao, W. Guo, Y. Shimizu, C. T. Liu, P. K. Liaw, K. Inoue, Y. Nagai, A. Hu, J. J. Kai

Research output: Contribution to journalArticlepeer-review

58 Citations (Scopus)

Abstract

A FeCoNiCrTi0.2 high-entropy alloy strengthened by two types of coherent nano-precipitates but with the same composition was fabricated, and its tensile properties at room (293 K) and cryogenic temperatures (77 K) and the corresponding defect-structure evolution were investigated. Compared with the single-phase FeCoNiCr parent alloy, the precipitation-strengthened FeCoNiCrTi0.2 high-entropy alloy exhibits a significant increase in yield strength and ultimate tensile strength but with little sacrifice in ductility. Similar to the single-phase FeCoNiCr high-entropy alloy, the deformation behavior of this precipitation-strengthened FeCoNiCrTi0.2 high-entropy alloy shows strong temperature dependence. When the temperature decreases from 293 K to 77 K, its yield strength and ultimate tensile strength are increased from 700 MPa to 860 MPa and from 1.24 GPa to 1.58 GPa, respectively, associated with a ductility improvement from 36% to 46%. However, different from the single-phase FeCoNiCr high-entropy alloy with a twinning-dominant deformation mode at 77 K, multiple-layered stacking faults with a hierarchical substructure prevail in the precipitation-strengthened FeCoNiCrTi0.2 high-entropy alloy when deformed at 77 K. The mechanism of twinning inhibition in this precipitation-strengthened high-entropy alloy is the high energy barrier for twin nucleation in the ordered γ′ nano-particles. Our results may provide a guide for the design of tough high-entropy alloys for applications at cryogenic temperatures through combining precipitation strengthening and twinning/stacking faults.

Original languageEnglish
Pages (from-to)228-240
Number of pages13
JournalActa Materialia
Volume165
DOIs
Publication statusPublished - 2019 Feb 15

Keywords

  • Deformation mechanism
  • High-entropy alloys
  • Precipitation strengthening
  • Stacking fault

ASJC Scopus subject areas

  • Electronic, Optical and Magnetic Materials
  • Ceramics and Composites
  • Polymers and Plastics
  • Metals and Alloys

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