The role of multi-elements and interlayer on the oxidation behaviour of (Hf-Ta-Zr-Nb)C high entropy ceramics

Wang, Yichen; Zhang, Ruizhi; Zhang, Buhao; Skurikhina, Olha; Baláž, Peter; Araullo‐Peters, Vicente; Reece, Michael J.

doi:10.1016/j.corsci.2020.109019

Cited by 82 publications

(31 citation statements)

References 36 publications

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“…Gild et al [34] first developed a variety of high-entropy borides (HEBs), which exhibited much better oxidation resistance than the individual borides at 1000-1200 ℃ for 1 h. [189,190] were investigated by several research groups. Similar to HEBs, all these high-entropy carbides exhibited better oxidation resistance than the individual transition-metal carbides.…”

Section: Oxidationmentioning

confidence: 99%

“…Therefore, the outward diffusion of TiO was also observed in the oxidation process of (Hf 0. Previous studies showed that Hf/Zr-rich oxide layer formed the outer layer followed by a Ta/Nb-rich oxide inner layer based on the similarity solution principle [186][187][188][189][190][191]. The formed sequential oxide layer structure during oxidation was mainly attributed to the selective oxidation among the multicomponent cations.…”

Section: Oxidationmentioning

confidence: 99%

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High-entropy ceramics: Present status, challenges, and a look forward

et al. 2021

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High-entropy ceramics (HECs) are solid solutions of inorganic compounds with one or more Wyckoff sites shared by equal or near-equal atomic ratios of multi-principal elements. Although in the infant stage, the emerging of this new family of materials has brought new opportunities for material design and property tailoring. Distinct from metals, the diversity in crystal structure and electronic structure of ceramics provides huge space for properties tuning through band structure engineering and phonon engineering. Aside from strengthening, hardening, and low thermal conductivity that have already been found in high-entropy alloys, new properties like colossal dielectric constant, super ionic conductivity, severe anisotropic thermal expansion coefficient, strong electromagnetic wave absorption, etc., have been discovered in HECs. As a response to the rapid development in this nascent field, this article gives a comprehensive review on the structure features, theoretical methods for stability and property prediction, processing routes, novel properties, and prospective applications of HECs. The challenges on processing, characterization, and property predictions are also emphasized. Finally, future directions for new material exploration, novel processing, fundamental understanding, in-depth characterization, and database assessments are given.

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Section: Oxidationmentioning

confidence: 99%

Section: Oxidationmentioning

confidence: 99%

High-entropy ceramics: Present status, challenges, and a look forward

et al. 2021

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“…A separate study in air found improved oxidation resistance in (HfNbTaZr)C compared to the five-metal carbide [76,77]. The four-metal carbide also showed improved performance compared to the binary carbide reactants, and the oxide layer was more structurally stable than in (HfTa)C, even though (HfTa)C had a lower oxidation onset temperature [76]. Mechanistic studies confirmed that outward diffusion of TiO is the rate-determining step in the oxidation of (HfNbTa-TiZr)C and thus key to increased corrosion resistance of (HfNbTaZr)C [78].…”

Section: Disorder-enhanced Propertiesmentioning

confidence: 94%

Section: Disorder-enhanced Propertiesmentioning

confidence: 99%

High-entropy ceramics: propelling applications through disorder

Toher¹,

Oses²,

Esters³

et al. 2021

Preprint

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Disorder enhances desired properties, as well as creating new avenues for synthesizing materials. For instance, hardness and yield stress are improved by solid-solution strengthening, a result of distortions and atomic size mismatches. Thermo-chemical stability is increased by the preference of chemically disordered mixtures for high-symmetry super-lattices. Vibrational thermal conductivity is decreased by force-constant disorder without sacrificing mechanical strength and stiffness. Thus, high-entropy ceramics propel a wide range of applications: from wear resistant coatings and thermal and environmental barriers to catalysts, batteries, thermoelectrics and nuclear energy management. Here, we discuss recent progress of the field, with a particular emphasis on disorder-enhanced properties and applications.

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“…For example, the hardness of the (HfNbTaTiZr)C carbide ranged from 29.7 to ∼40 GPa, while possessing 3–6‐MPa m 1/2 fracture toughness 16,18,28 . In addition to mechanical properties, HECCs, such as (HfZrTaNbTi)C, (HfTaZrNb)C, (ZrTaNbTi)C, and (HfMoNbTaTi)C, were found also outperforming conventional binary TMCs on the resistance to oxidation, 29‐32 radiation, 33 and wear 34 …”

Section: Introductionmentioning

confidence: 99%

Toughening (NbTaZrW)C high‐entropy carbide ceramic through Mo doping

Zhang

et al. 2022

J Am Ceram Soc.

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Previously, we investigated the mechanical properties of a series of multi‐cation high‐entropy ceramic carbides and found that (NbTaZrW)C exhibits the best combination of nanohardness and toughness. In the current study, we explored the possibility of further hardening and/or toughening of this carbide through cation‐site Mo doping. The results show that MoC has at least 20 at.% solubility in (NbTaZrW)C. There is a tight positive relationship between average lattice distortion and mixing enthalpy; and when cation‐site Mo content is below 10 at.%, the “entropy effect” outweighs the “enthalpy effect,” leading to increased phase stability. As Mo content increases, the sacrifice of hardening is much less pronounced in comparison with that of the achievement of toughening. Quantitatively, as Mo in cation sites increases to 20 at.%, the toughness of (NbTaZrW)C is increased by ∼18%, whereas the nanohardness undergoes only ∼7% reduction. More intriguing, the 5 at.% Mo‐doped (NbTaZrW)C exhibits simultaneous improvement of nanohardness and toughness. This hardening/toughening behavior is associated with the complex and hybrid effects from lattice distortion, bonding nature as well as dislocation slip behavior. In general, this study shows the possibility of paving the way for the design and search of novel transition metal carbides with a better combination of hardness and toughness.

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The role of multi-elements and interlayer on the oxidation behaviour of (Hf-Ta-Zr-Nb)C high entropy ceramics

Cited by 82 publications

References 36 publications

High-entropy ceramics: Present status, challenges, and a look forward

High-entropy ceramics: Present status, challenges, and a look forward

High-entropy ceramics: propelling applications through disorder

Toughening (NbTaZrW)C high‐entropy carbide ceramic through Mo doping

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