Cryogenic-temperature fracture toughness analysis of non-equi-atomic V10Cr10Fe45Co20Ni15 high-entropy alloy

Yong Hee Jo, Kyung Yeon Doh, Dong Geun Kim, Kwanho Lee, Dae Woong Kim, Hyokyung Sung, Seok Su Sohn, Donghwa Lee, Hyoung Seop Kim, Byeong Joo Lee, Sunghak Lee

Research output: Contribution to journalArticlepeer-review

6 Citations (Scopus)

Abstract

Representative face-centered-cubic (FCC) high-entropy alloys (HEAs) or medium-entropy alloys (MEAs), e.g., equi-atomic CoCrFeMnNi or CrCoNi alloys, have drawn many attentions due to the excellent damage-tolerance at cryogenic temperature. The investigation of fracture toughness at 77 K is basically required for the reliable evaluation of high-performance alloys used for cryogenic applications; however, it has been rarely carried out for the non-equi-atomic FCC HEAs yet. In this study, tensile and fracture toughness tests were conducted on the non-equi-atomic V10Cr10Fe45Co20Ni15 alloy, and the results were compared with those of the equi-atomic CoCrFeMnNi and CrCoNi alloys. The present alloy shows a good damage tolerance at cryogenic temperature with tensile strength of 1 GPa and elongation of ∼60%. The KJIc fracture toughness values are 219 and 232 MPa m1/2 at 298 and 77 K, respectively, showing the increase in toughness with decreasing temperature. This increase results from the absence of twins at 298 K and the increased propensity to twin formation at 77 K, which is well confirmed by the variation of stacking fault energies (SFEs) by using Ab-initio calculations. The mechanical properties of the present alloy are actually similar or slightly lower than those of the other CoNiCr or FeMnCoNiCr alloy; instead, this study provides that neither composition nor certain elements are the most important factors dictating damage-tolerance of HEAs or MEAs.

Original languageEnglish
Article number151864
JournalJournal of Alloys and Compounds
Volume809
DOIs
Publication statusPublished - 2019 Nov 15

Keywords

  • Ab-initio calculation
  • Cryogenic temperature
  • Fracture toughness
  • High-entropy alloy (HEA)
  • Stacking fault energy (SFE)

ASJC Scopus subject areas

  • Mechanics of Materials
  • Mechanical Engineering
  • Metals and Alloys
  • Materials Chemistry

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