Clarification of phase stability and oxidation mechanism for TiZrHfTaX (X = Ta, Cr) using thermodynamic calculation

Yuki Komiya, Daiki Haginiwa, Yasuo Kogo, Yutaro Arai

Research output: Contribution to journalArticlepeer-review

Abstract

TiZrHfNbX (X = Ta, Cr) alloys were prepared as refractory high-entropy alloys (RHEAs) using an arc-melting method to investigate the differences in their oxidation behavior. Thermogravimetric analysis (TGA) and isothermal oxidation at 1200 °C for 4 h revealed that the weight gain of TiZrHfNbCr is larger than that of TiZrHfNbTa, and the preferential oxidation of Hf and Zr occurs in TiZrHfNbCr. After oxidation, complex oxides with structures (Zr, Hf)6(Nb, Ta)2O17, Ti(Nb, Ta)2O7, and Cr(Nb, Ta)O2 were formed, and these complex oxides probably acted as barriers for oxygen diffusion during oxidation. To gain in-depth understanding about the role of these oxides during oxidation, the oxidation behavior of middle- and low-entropy alloys with higher (Ti, Zr, and Hf) and lower (Nb, Ta, and Cr) Gibbs free energies of oxidation was investigated. Graphical abstract: [Figure not available: see fulltext.]

Original languageEnglish
JournalMRS Advances
DOIs
Publication statusAccepted/In press - 2022

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