Oxidation behaviors of CrNb, CrNbTi, and CrNbTaTi concentrated refractory alloys

Butler, T.M.; Senkov, O.N.; Daboiku, T.I.; Velez, Michael; Schroader, H.E.; Ware, L.G.; Titus, Michael S.

doi:10.1016/j.intermet.2021.107374

Cited by 30 publications

(3 citation statements)

References 34 publications

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“…It is unclear; therefore, how compositional complexity and microstructure affect these alloys' oxidation processes [29]. Fe 35 Mn 28 Ni 20 Cr 12 Al 5 HEA was manufactured with FCC structure with good mechanical characteristics [30,31]. In addition, the oxidation behavior was examined in the air for 100 h at 900, 1000, and 1100 HEA in the cold rolled condition is studied at the medium temperature range of 500, 600, and 700 • C for 50 h in dry air.…”

Section: Introductionmentioning

confidence: 99%

Oxidation of Fe35Mn21Ni20Cr12Al12 High Entropy Alloy in Dry Air

Mohamed,

Abd ElMoamen,

Yoo

et al. 2024

Alloys

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The isothermal oxidation of a Fe35Mn21Ni20Cr12Al12 high entropy alloy (HEA) was investigated in dry air for 50 h at 500, 600, and 700 °C after 90% cold rolling. The Fe35Mn21Ni20Cr12Al12 HEA behaves according to the linear oxidation rate with rate constants of 1 × 10−6, 3 × 10−6, and 7 × 10−6 g/(cm2·s) for oxidation at 500 °C, 600 °C, and 700 °C, respectively. The activation energy for oxidation of the HEA was calculated to be 60.866 KJ/mole in the 500–700 °C temperature range. The surface morphology and phase identification of the oxide layers were characterized. The formation of MnO2, Mn2O3, Mn3O4, Cr2O3, and Al2O3 in the oxide layers along with Fe2O3 is the key to the oxidation mechanism. The elemental mapping and line EDX scans were performed to identify the oxidation mechanisms.

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Section: Introductionmentioning

confidence: 99%

Oxidation of Fe35Mn21Ni20Cr12Al12 High Entropy Alloy in Dry Air

Mohamed,

Abd ElMoamen,

Yoo

et al. 2024

Alloys

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“…Here, the focus is restricted to refractory HEAs (RHEAs), which are promising candidate materials for high-temperature structural applications, such as their use in jet propulsion systems as the structural material for the engine turbine blades and discs. Senkov and associates have carried out extensive experimental investigations on the mechanical properties, phase stability, and high-temperature oxidation behavior of refractory alloy systems to examine the viability of deploying them in aircraft propulsion systems. − Several RHEAs have been thoroughly discussed and recently reviewed by Couzinie et al Experimental studies on the high-temperature oxidation resistance of RHEAs and the role different metals play are ongoing. − Butler and Weaver explored Al x (NiCoCrFe) 1– x in which the Al content was varied. They reported a combination of Al 2 O 3 and AlN beneath an external Cr 2 O 3 scale across all samples with the general conclusion that increasing Al content improved the oxidation resistance by bolstering the position and continuity of the Al 2 O 3 scale.…”

Section: Introductionmentioning

confidence: 99%

“…where E slab O(n) is the total electronic energy of the oxidized slab, E slab is the total electronic energy of the clean slab, n is the number of O atoms present, E O 2 is the energy of the gas-phase O 2 molecule, and ) is the difference in electronic energy between the surface with n O atoms and n + 1 O atoms present. The electronic energy of O 2 was calculated by placing two O atoms in a box of dimensions (8,8,8) Å separated along the ĉdirection by 1.22 Å. The electronic energy was converged with respect to box size.…”

Section: ■ Introductionmentioning

confidence: 99%

Adsorption of Oxygen to High Entropy Alloy Surfaces for up to 2 ML Coverage Using Density Functional Theory and Monte Carlo Calculations

Doležal

Samin

2022

Langmuir

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High-entropy alloys (HEAs) manufactured with refractory elements are candidates for high-temperature structural applications. To enhance our understanding of oxidation in these complex systems, the early stages of oxidation on the surface of Al 10 Nb 15 Ta 5 Ti 30 Zr 40 were studied using density functional theory and thermodynamic modeling. Surface slabs were generated from bulk configurations sampled from equilibrium using a multicell Monte Carlo method for phase prediction. The bulk structure was found to be a single BCC phase in good agreement with experimental observations. The oxygen adsorbed with a strong preference for sites with Ti and Zr and avoided sites with Nb−Al and Nb−Ta. The surface was shown to be highly reactive to oxygen, yielding a dominating oxygen coverage of two monolayers over the temperature range of 100 to 2600 K and an oxygen pressure range of 10 −30 to 10 5 bar. Recovering a clean surface slab was not achieved until pressures approached vacuum conditions and temperature exceeded 1900 K, demonstrating the difficulty of oxygen removal from the surface. Grand canonical Monte Carlo simulations showed that high Nb content in the top surface layer reduced the surface reactivity to incoming oxygen. Inward oxygen diffusion at low coverage was preferred in regions rich with Zr but slowed with the addition of Ti and Al. Diffusion rates drastically decreased at 1 ML, especially in the region rich with Ti and Zr, where strong metal−oxygen bonds were reported. Our results indicated that a high content of Ti and Zr increased the reactivity of the HEA surface to oxygen. The presence of Nb also enhanced the resistance to oxygen adsorption, especially when partnered with Al and Ta. Inward oxygen diffusion was likely to occur at low coverage in regions rich with Zr but could be protected against with the addition of Al and Ti. The limitations of the present work are discussed. This study may provide insights that assist with devising short-and long-term mitigation strategies against material degradation related to high-temperature oxidation.

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