In situ oxidation studies of high-entropy alloy nanoparticles

Boao Song, Yong Yang, Muztoba Rabbani, Timothy T. Yang, Kun He, Xiaobing Hu, Yifei Yuan, Pankaj Ghildiyal, Vinayak P. Dravid, Michael R. Zachariah*, Wissam A. Saidi, Yuzi Liu, Reza Shahbazian-Yassar

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

6 Scopus citations

Abstract

Although high-entropy alloys (HEAs) have shown tremendous potential for elevated temperature, anticorrosion, and catalysis applications, little is known on how HEA materials behave under complex service environments. Herein, we studied the high-temperature oxidation behavior of Fe0.28Co0.21Ni0.20Cu0.08Pt0.23HEA nanoparticles (NPs) in an atmospheric pressure dry air environment by in situ gas-cell transmission electron microscopy. It is found that the oxidation of HEA NPs is governed by Kirkendall effects with logarithmic oxidation rates rather than parabolic as predicted by Wagner’s theory. Further, the HEA NPs are found to oxidize at a significantly slower rate compared to monometallic NPs. The outward diffusion of transition metals and formation of disordered oxide layer are observed in real time and confirmed through analytical energy dispersive spectroscopy, and electron energy loss spectroscopy characterizations. Localized ordered lattices are identified in the oxide, suggesting the formation of Fe2O3, CoO, NiO, and CuO crystallites in an overall disordered matrix. Hybrid Monte Carlo and molecular dynamics simulations based on first-principles energies and forces support these findings and show that the oxidation drives surface segregation of Fe, Co, Ni, and Cu, while Pt stays in the core region. The present work offers key insights into how HEA NPs behave under high-temperature oxidizing environment and sheds light on future design of highly stable alloys under complex service conditions.

Original languageEnglish (US)
Pages (from-to)15131-15143
Number of pages13
JournalACS nano
Volume14
Issue number11
DOIs
StatePublished - Nov 24 2020

Keywords

  • High-entropy alloys
  • In situ transmission electron microscopy
  • Kirkendall
  • Nanoparticles
  • Oxidation
  • Phase segregation

ASJC Scopus subject areas

  • Materials Science(all)
  • Engineering(all)
  • Physics and Astronomy(all)

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