Interstitial-oxygen induced and magnetically driven HCP-to-FCC transformation in CoCrFeNiOx high-entropy alloy: a first-principles study

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Abstract

We report the influences of oxygen interstitials and magnetisms on phase stability and structural transformation of CoCrFeNi high-entropy alloy (HEA) from first-principles calculations. It is found the formation of oxygen interstitials is energetically favourable to occur in face-centred cubic (FCC) CoCrFeNiOx HEA as compared with that in hexagonal close-packed (HCP) one, and at those octahedral sites neighbouring with more Cr or less Ni. Meanwhile, it is determined the HEA prefers FCC over HCP phases when the oxygen concentration exceeds 4.2 and 5.1 at.% with and without considering its magnetisms, respectively. The HCP-to-FCC structural transformation in CoCrFeNiOx HEA could be magnetically driven, accompanied by the significant changes in the atomic magnetic moments in the HEA, particularly with an oxygen interstitial concentration larger than 2.7 at.%. Furthermore, the HCP-to-FCC transformation under hydrostatic pressure in CoCrFeNi and CoCrFeNiOx HEAs is investigated from generalised stacking fault energies, and it is revealed that the synergy effects of oxygen interstitials and magnetisms could facilitate the transformation in CoCrFeNiOx HEA. The coupled interstitials-induced and magnetically driven structural transformation paves a new avenue for the application of HEAs.

Original languageEnglish
Pages (from-to)2123-2140
Number of pages18
JournalPhilosophical Magazine
Volume103
Issue number23
DOIs
Publication statusPublished - Oct 2023

Keywords

  • CoCrFeNi high entropy alloy
  • first-principles calculation
  • Interstitials
  • magnetisms
  • phase transformations

ASJC Scopus subject areas

  • Condensed Matter Physics

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