Accelerated oxidation in ductile refractory high-entropy alloys

Saad Sheikh, Muhammad Kurnia Bijaksana, Amir Motallebzadeh, Samrand Shafeie, Adrianna Lozinko, Lu Gan, Te Kang Tsao, Uta Klement, Demircan Canadinc, Hideyuki Murakami, Sheng Guo*

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

82 Citations (Scopus)


Refractory high-entropy alloys (RHEAs) are promising candidates for new-generation high temperature materials, but they generally suffer from room temperature brittleness and unsatisfactory high-temperature oxidation resistance. There currently lack efforts to address to these two critical issues for RHEAs at the same time. In this work, the high temperature oxidation resistance of a previously identified ductile Hf0.5Nb0.5Ta0.5Ti1.5Zr RHEA is studied. An accelerated oxidation or more specifically, pesting, in the temperature range of 600–1000 °C is observed for the target RHEA, where the oxidation leads the material to catastrophically disintegrate into powders. The pesting mechanism is studied here, and is attributed to the failure in forming protective oxide scales accompanied by the accelerated internal oxidation. The simultaneous removal of zirconium and hafnium can eliminate the pesting phenomenon in the alloy. It is believed that pesting can also occur to other equiatomic and non-equiatomic quinary Hf-Nb-Ta-Ti-Zr or quaternary Hf-Nb-Ti-Zr and Hf-Ta-Ti-Zr RHEAs, where all currently available ductile RHEAs are identified. Therefore, the results from this work will provide crucial perspectives to the further development of RHEAs as novel high-temperature materials, with balanced room-temperature ductility and high-temperature oxidation resistance.

Original languageEnglish
Pages (from-to)58-66
Number of pages9
Publication statusPublished - 2018 Jun


  • High temperature materials
  • Oxidation resistance
  • Pesting
  • Refractory high-entropy alloys

ASJC Scopus subject areas

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


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