Interatomic spacing distribution in multicomponent alloys

Toda‐Caraballo, Isaac; Wróbel, Jan; Dudarev, S. L.; Nguyen-Manh, D.; Rivera-Dı́az-del-Castillo, P.E.J.

doi:10.1016/j.actamat.2015.07.010

Cited by 110 publications

(62 citation statements)

References 51 publications

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“…This indicates an almost constant and volume-independent ∆E σ relax . We note that our results are also in good agreement with previous calculations [30]. In order to evaluate the impact of B2 ordering on the thermodynamic properties, we compute the Gibbs energies of both phases, G σ (T), from which thermodynamic properties such as the volume expansion or heat capacity can be derived.…”

Section: Resultssupporting

confidence: 63%

“…From the different ∆E σ relax contributions for A2 and B2, we can conclude that local atomic relaxations will have an impact on the ordering temperature, which we will discuss below. [30] 17.08 228 n/a n/a n/a Experiment [4] 16.70 220 ---Before discussing the ordering temperature, we first investigate the impact of B2 ordering on ground state and thermodynamic properties. In Table 1, we summarize the ground state volume, V 0 , bulk modulus, B 0 , and its derivative, B , derived from the ground state energies in Figure 1.…”

Section: Resultsmentioning

confidence: 99%

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Interplay between Lattice Distortions, Vibrations and Phase Stability in NbMoTaW High Entropy Alloys

Körmann

Sluiter

2016

Entropy

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Refractory high entropy alloys (HEA), such as BCC NbMoTaW, represent a promising materials class for next-generation high-temperature applications, due to their extraordinary mechanical properties. A characteristic feature of HEAs is the formation of single-phase solid solutions.For BCC NbMoTaW, recent computational studies revealed, however, a B2(Mo,W;Nb,Ta)-ordering at ambient temperature. This ordering could impact many materials properties, such as thermodynamic, mechanical, or diffusion properties, and hence be of relevance for practical applications. In this work, we theoretically address how the B2-ordering impacts thermodynamic properties of BCC NbMoTaW and how the predicted ordering temperature itself is affected by vibrations, electronic excitations, lattice distortions, and relaxation energies.

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Section: Resultssupporting

confidence: 63%

Section: Resultsmentioning

confidence: 99%

Interplay between Lattice Distortions, Vibrations and Phase Stability in NbMoTaW High Entropy Alloys

Körmann

Sluiter

2016

Entropy

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“…This level of strain is no greater than those predicted and measured in both dilute and concentrated binary alloys. 189,190,[196][197][198][199][200][201] Indeed, the displacements are of similar size to those expected from thermal vibrations around room temperature 185,190,196 and, therefore, cannot be described assevere.…”

Section: Pickering and Jones High-entropy Alloysmentioning

confidence: 99%

“…175,176 Well-established models for solution strengthening have been produced for both dilute and concentrated alloys, [177][178][179] and their modification for HEAs is discussed in Section 8 of this article. A number of studies have suggested that severe lattice distortion contributes significantly to HEA properties, 3,65,75,84,85,97,165,[180][181][182][183][184][185][186] most notably with respect to increasing alloy strength, see for instance 165,187 . Importantly, however, it is apparent that the strengthening effect of precipitates may have been overlooked in some cases.…”

Section: Severely Distorted Latticesmentioning

confidence: 99%

High-entropy alloys: a critical assessment of their founding principles and future prospects

Pickering

Jones

2016

International Materials Reviews

736

299

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High-entropy alloys (HEAs) are a relatively new class of materials that have gained considerable attention from the metallurgical research community over recent years. They are characterised by their unconventional compositions, in that they are not based around a single major component, but rather comprise multiple principal alloying elements. Four core effects have been proposed in HEAs: (1) the entropic stabilisation of solid solutions, (2) the severe distortion of their lattices, (3) sluggish diffusion kinetics and (4) that properties are derived from a cocktail effect. By assessing these claims on the basis of existing experimental evidence in the literature, as well as classical metallurgical understanding, it is concluded that the significance of these effects may not be as great as initially believed. The effect of entropic stabilisation does not appear to be overarching, insufficient evidence exists to establish the strain in the lattices of HEAs, and rapid precipitation observed in some HEAs suggests their diffusion kinetics are not necessarily anomalously slow in comparison to conventional alloys. The meaning and influence of the cocktail effect is also a matter for debate. Nevertheless, it is clear that HEAs represent a stimulating opportunity for the metallurgical research community. The complex nature of their compositions means that the discovery of alloys with unusual and attractive properties is inevitable. It is suggested that future activity regarding these alloys seeks to establish the nature of their physical metallurgy, and develop them for practical applications. Their use as structural materials is one of the most promising and exciting opportunities. To realise this ambition, methods to rapidly predict phase equilibria and select suitable HEA compositions are needed, and this constitutes a significant challenge. However, while this obstacle might be considerable, the rewards associated with its conquest are even more substantial. Similarly, the challenges associated with comprehending the behaviour of alloys with complex compositions are great, but the potential to enhance our fundamental metallurgical understanding is more remarkable. Consequently, HEAs represent one of the most stimulating and promising research fields in materials science at present.

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“…The first models that attempted to quantify this effect were introduced about seven decades ago; 1-4 since then, many refinements have been proposed, continuing to the present. [5][6][7][8][9][10][11][12][13][14][15] Recently, complex solid solutions comprising multiple principal elements, often referred to as high-entropy alloys (HEAs), a name coined by Yeh et al [Ref. 16], have been receiving tremendous attention in the literature [e.g., Refs.…”

mentioning

confidence: 99%

Atomic displacement in the CrMnFeCoNi high-entropy alloy – A scaling factor to predict solid solution strengthening

et al. 2016

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Although metals strengthened by alloying have been used for millennia, models to quantify solid solution strengthening (SSS) were first proposed scarcely seventy years ago. Early models could predict the strengths of only simple alloys such as dilute binaries and not those of compositionally complex alloys because of the difficulty of calculating dislocation-solute interaction energies. Recently, models and theories of SSS have been proposed to tackle complex high-entropy alloys (HEAs). Here we show that the strength at 0 K of a prototypical HEA, CrMnFeCoNi, can be scaled and predicted using the root-mean-square atomic displacement, which can be deduced from X-ray diffraction and first-principles calculations as the isotropic atomic displacement parameter, that is, the average displacements of the constituent atoms from regular lattice positions. We show that our approach can be applied successfully to rationalize SSS in FeCoNi, MnFeCoNi, MnCoNi, MnFeNi, CrCoNi, CrFeCoNi, and CrMnCoNi, which are all medium-entropy subsets of the CrMnFeCoNi HEA.

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Interatomic spacing distribution in multicomponent alloys

Cited by 110 publications

References 51 publications

Interplay between Lattice Distortions, Vibrations and Phase Stability in NbMoTaW High Entropy Alloys

Interplay between Lattice Distortions, Vibrations and Phase Stability in NbMoTaW High Entropy Alloys

High-entropy alloys: a critical assessment of their founding principles and future prospects

Atomic displacement in the CrMnFeCoNi high-entropy alloy – A scaling factor to predict solid solution strengthening

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