On the oxidation mechanism of refractory high entropy alloys

Müller, Frank; Gorr, Bronislava; Christ, Hans‐Jürgen; Müller, Julian; Butz, Benjamin; Chen, Hans; Kauffmann, Alexander; Heilmaier, Martin

doi:10.1016/j.corsci.2019.108161

Cited by 143 publications

(114 citation statements)

References 39 publications

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“…1a). The results of oxidation tests performed in our earlier study at 1000°C revealed that the outer scale did not change markedly in terms of the constituting oxides and their ratio even after extended oxidation up to 300h [19]. We thus anticipate a similar behavior at the higher temperatures tested here, although experimental proof should be left for future work.…”

Section: Resultssupporting

confidence: 55%

“…The results of the oxidation tests performed on the equiatomic RHEA Ta-Mo-Cr-Ti-Al at 900°C, 1000°C and 1100° were presented and discussed in ref. [19]. In the current study, the range of temperature is expanded to 500°C, 1300°C, 1400°C and 1500°C.…”

Section: Resultsmentioning

confidence: 99%

“…at 900°C, see ref. [19]. A deeper insight into the protective properties of the oxide scales is given in Figs.…”

Section: Resultsmentioning

confidence: 99%

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A new strategy to intrinsically protect refractory metal based alloys at ultra high temperatures

et al. 2020

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Poor oxidation resistance represents one of the main shortcomings of refractory metal based alloys. This work shows an innovative way to intrinsically protect such materials. Our approach relies on the alloying with Cr and Ta allowing the formation of CrTaO4. The CrTaO4 scale formed on the novel refractory equiatomic high entropy alloy Ta-Mo-Cr-Ti-Al reveals a unique combination of the following properties: (i) easy formation in a wide temperature range from 500°C to 1500°C, (ii) excellent adherence after cooling, (iii) low growth rates, and (iv) wide stability range of the stoichiometric composition that suppresses the formation of non-protective oxides.

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Section: Resultssupporting

confidence: 55%

Section: Resultsmentioning

confidence: 99%

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A new strategy to intrinsically protect refractory metal based alloys at ultra high temperatures

et al. 2020

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“…Moreover, the ternary oxide phase instead of the individual binary oxide may form during high-temperature oxidation. Müller et al [36] have reported that TaMoCrTiAl yields the crystal phases of TiO 2 , Al 2 O 3 , Cr 2 O 3 , and CrTaO 4 after annealing at 1000 • C. Tsai et al [37] have oxidized (TiVCrZrHf)N at 600 • C to form the (Zr, Hf)TiO 4 crystal phase. Ren et al [38] have detected that Ni-based superalloys consists of Cr 2 O 3 , TiO 2 , NiCr 2 O 4 , Al 2 O 3 , and CrTaO 4 crystal phases after annealing at 850 • C. In general, the ternary oxide has higher crystallization temperatures than binary oxide, thereby expanding the amorphous temperature.…”

Section: Resultsmentioning

confidence: 99%

Oxidation Behavior and Structural Transformation of (CrTaTiVZr)N Coatings

Chang

Liang

2020

Coatings

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(CrTaTiVZr)N coatings were prepared on Si substrates through the reactive magnetron sputtering system to investigate the oxidation behaviors and structural evolution of the coatings at different annealing temperatures in air. The (CrTaTiVZr)N coating had a face-centered cubic structure with an oxidation temperature of up to 300 °C, but its surface changed into the amorphous oxide phase and then into the rutile TiO2 phase when the annealing temperature was increased to 500 °C. The rutile TiO2 phase continued to grow, and an additional solid solution phase of body-centered tetragonal I41/amd was formed at annealing temperatures beyond 600 °C. The high annealing temperature promoted the oxidation to progress along the thickness direction and synergistically developed the porosity. As a result, the hardness and the electrical performance of the coating deteriorated. The hardness decreased from 34.30 GPa to 1.52 GPa, and the electrical resistivity increased from 142 µΩ·cm to 17.5 Ω·cm.

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“…HEAs have been reported with high hardness and high compressive strength, both at room temperature and at elevated temperatures [5][6][7]. They have also been reported to possess outstanding wear [8,9] and oxidation [10,11] resistance, as well as high thermal stability [12]. However, the researches on corrosion resistance are comparatively rare.…”

Section: Introductionmentioning

confidence: 99%

Electrochemical Study of MoTaNbVTi High Entropy Alloy in Aqueous Environments

Poulia¹,

Mathiou²,

Karantzalis³

2019

ACSM

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The purpose of this study is to investigate the corrosion behavior of MoTaNbVTi refractory high entropy alloy in 3.5 wt.% NaCl and Hank solution. Regarding the sea water testing environment, data from the electrochemical analysis of the polarization curves created some first suspicions about a local corrosion tendency. However, the corroded surfaces and crosssections' Scanning Electron Microscopy and Energy Dispersive Spectroscopy analysis verified no signs of any type of degradation. Moreover, the results indicate that no selective corrosion along the inter-dendritic regions of the alloy, was found. As far as the Hank solution is concerned, once again, some preliminary considerations of a possible susceptibility to local forms of corrosion were shown off, however, no evidence of corrosion signs (either pericrystalline or pitting) was detected. The findings of this research suggest that MoTaNbVTi presented an excellent response to these types of corrosion environments and could be used as an ideal candidate for that kind of applications.

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On the oxidation mechanism of refractory high entropy alloys

Cited by 143 publications

References 39 publications

A new strategy to intrinsically protect refractory metal based alloys at ultra high temperatures

A new strategy to intrinsically protect refractory metal based alloys at ultra high temperatures

Oxidation Behavior and Structural Transformation of (CrTaTiVZr)N Coatings

Electrochemical Study of MoTaNbVTi High Entropy Alloy in Aqueous Environments

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