Oxidation resistance of Al-containing refractory high-entropy alloys

Elaf A. Anber, David Beaudry, Charlie Brandenburg, Sebastian Lech, Lavina Backman, Daniel L. Foley, Emily L. Wang, Michael Joseph Waters, Loic Perriere, Jean Philippe Couzinie, James M. Rondinelli, Elizabeth Opila, Mitra L. Taheri*

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

Abstract

Refractory high entropy alloys (RHEAs) hold the promise of superior mechanical properties at high temperatures but are plagued by a lack of oxidation resistance. In this work, the role of Al additions (4.8, and 13 at.%) to HfNbTaTiZr is explored as a means of improving protective oxide scale formation in RHEAs. Oxide formation was resolved using STEM-EDS/EELS, precession electron diffraction, and computational predictions of formation energy. Our results show that oxides with large negative formation energies (i.e., HfO2/ZrO2) always formed near the metal/oxide interface while Al2O3 and oxides with less negative formation energies formed near the surface. The addition of Al prevented pesting in both alloys and formed Al2O3 with 13 at.% Al. While the Al2O3 formed was not continuous, we report the lowest threshold yet to prevent pesting with only 4.8 at.% Al added. These findings provide guidance to future alloy development of Al2O3-forming alloys.

Original languageEnglish (US)
Article number115997
JournalScripta Materialia
Volume244
DOIs
StatePublished - Apr 15 2024

Keywords

  • Al2O3 scale
  • AlZr2 intermetallic
  • Fact-Sage calculations, TGA
  • Refractory high entropy alloys

ASJC Scopus subject areas

  • General Materials Science
  • Condensed Matter Physics
  • Mechanics of Materials
  • Mechanical Engineering
  • Metals and Alloys

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