Discovery of a Superconducting High-Entropy Alloy

Koželj, Primož; Vrtnik, S.; Jelen, Andreja; Jazbec, Saša Šega; Jagličić, Zvonko; Maiti, Soumyadipta; Feuerbacher, M.; Steurer, Walter; Dolinšek, J.

doi:10.1103/physrevlett.113.107001

Cited by 431 publications

(271 citation statements)

References 16 publications

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“…3 Refractory HEAs, such as e.g. bcc NbMoTaW, possess extraordinary mechanical properties, comparable to current state-of-the-art nickel-based superalloys.…”

Section: Introductionmentioning

confidence: 99%

Phonon broadening in high entropy alloys

et al. 2017

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Refractory high entropy alloys feature outstanding properties making them a promising materials class for next-generation hightemperature applications. At high temperatures, materials properties are strongly affected by lattice vibrations (phonons). Phonons critically influence thermal stability, thermodynamic and elastic properties, as well as thermal conductivity. In contrast to perfect crystals and ordered alloys, the inherently present mass and force constant fluctuations in multi-component random alloys (high entropy alloys) can induce significant phonon scattering and broadening. Despite their importance, phonon scattering and broadening have so far only scarcely been investigated for high entropy alloys. We tackle this challenge from a theoretical perspective and employ ab initio calculations to systematically study the impact of force constant and mass fluctuations on the phonon spectral functions of 12 body-centered cubic random alloys, from binaries up to 5-component high entropy alloys, addressing the key question of how chemical complexity impacts phonons. We find that it is crucial to include both mass and force constant fluctuations. If one or the other is neglected, qualitatively wrong results can be obtained such as artificial phonon band gaps. We analyze how the results obtained for the phonons translate into thermodynamically integrated quantities, specifically the vibrational entropy. Changes in the vibrational entropy with increasing the number of elements can be as large as changes in the configurational entropy and are thus important for phase stability considerations. The set of studied alloys includes MoTa, MoTaNb,

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“…3 Refractory HEAs, such as e.g. bcc NbMoTaW, possess extraordinary mechanical properties, comparable to current state-of-the-art nickel-based superalloys.…”

Section: Introductionmentioning

confidence: 99%

Phonon broadening in high entropy alloys

et al. 2017

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“…For example, the so-called "sluggish diffusion" effect, a mass transport property, has been considered one of the core effects of HEAs, responsible to the outstanding high temperature properties (Tsai et al, 2013;Dabrowa et al, 2016;Vaidya et al, 2016). In addition, interesting electrical transport properties such as superconductivity (Koželj et al, 2014) and quantum critical behavior (Sales et al, 2016(Sales et al, , 2017 have been discovered, and the HEAs have been considered promising in functional applications such as thermoelectric materials (Shafeie et al, 2015;Fan et al, 2016) and soft ferromagnetic materials (Zhang et al, 2013). Furthermore, recent studies have linked the mass and energy transport properties to the enhanced irradiation resistance (Zhang et al, 2015;Lu et al, 2016b;Zhang Y. et al, 2017).…”

Section: Introductionmentioning

confidence: 99%

Single-Phase Concentrated Solid-Solution Alloys: Bridging Intrinsic Transport Properties and Irradiation Resistance

Jin

Bei

2018

Front. Mater.

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Single-phase concentrated solid-solution alloys (SP-CSAs), including high entropy alloys (HEAs), are compositionally complex but structurally simple, and provide a playground of tailoring material properties through modifying their compositional complexity. The recent progress in understanding the compositional effects on the energy and mass transport properties in a series of face-centered-cubic SP-CSAs is the focus of this review. Relatively low electrical and thermal conductivities, as well as small separations between the interstitial and vacancy migration barriers have been generally observed, but largely depend on the alloying constituents. We further discuss the impact of such intrinsic transport properties on their irradiation response; the linkage to the delayed damage accumulation, slow defect aggregation, and suppressed irradiation induced swelling and segregation has been presented. We emphasize that the number of alloying elements may not be a critical factor on both transport properties and the defect behaviors under ion irradiations. The recent findings have stimulated novel concepts in the design of new radiation-tolerant materials, but further studies are demanded to enable predictive models that can quantitatively bridge the transport properties to the radiation damage.

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“…Simple niobium-titanium-based binary alloys are nowadays still the most often and widely used materials for superconducting magnets, such as in NMR and MRI devices (11) or the Large Hadron Collider (12), and thus the discovery of bulk superconductivity with a single well-defined phase transition on a highly disordered BCC lattice in the Nb-Ti-related Ta-Nb-Hf-Zr-Ti HEA is of considerable interest (13,14). This multicomponent phase, stabilized by the high mixing entropy, appears to fall between an ordered solid and a glass and thus allows for study of the chemical composition and structure-property relations of a superconducting material partway between an ordinary alloy and an amorphous material on a fundamental level.…”

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Effect of electron count and chemical complexity in the Ta-Nb-Hf-Zr-Ti high-entropy alloy superconductor

Rohr

Winiarski

Tao

et al. 2016

Proc. Natl. Acad. Sci. U.S.A.

146

110

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High-entropy alloys are made from random mixtures of principal elements on simple lattices, stabilized by a high mixing entropy. The recently discovered body-centered cubic (BCC) Ta-Nb-Hf-Zr-Ti highentropy alloy superconductor appears to display properties of both simple crystalline intermetallics and amorphous materials; e.g., it has a well-defined superconducting transition along with an exceptional robustness against disorder. Here we show that the valence electron count dependence of the superconducting transition temperature in the high-entropy alloy falls between those of analogous simple solid solutions and amorphous materials and test the effect of alloy complexity on the superconductivity. We propose high-entropy alloys as excellent intermediate systems for studying superconductivity as it evolves between crystalline and amorphous materials.high-entropy alloys | superconductivity | disordered metals A lloys are among the most relevant materials for modern technologies. Conventional alloys typically consist of one principal element, such as the iron in steel, plus one or more dopant elements in small proportion (e.g., carbon in the case of steel) that enhance a certain property of interest; the properties are based on the modification of those of the principal element. In sharp contrast, highentropy alloys (HEAs) are composed of multiple principal elements that are all present in major proportion, with the simple structures observed attributed to the high configurational entropy of the random mixing of the elements on their lattice sites (1). Thus, the concept of a "principal element" becomes irrelevant. The elements in HEAs arrange on simple lattices with the atoms stochastically distributed on the crystallographic positions; HEAs are commonly referred to as metallic glasses on an ordered lattice ( Fig. 1 A and B). The properties of HEAs arise as a result of the collective interactions of the randomly distributed constituents (2, 3). There is no strict definition, but HEAs are typically composed of four or more major elements in similar concentrations. By applying this concept, several new alloys with simple body-centered cubic (BCC), hexagonal closest-packing (HCP), or face-centered cubic (FCC) structures have been realized (2, 3, 4). The HEAs compete for thermodynamic stability with crystalline intermetallic phases with smaller numbers of elemental constituents (5). Therefore, one central concept of designing these alloys is to understand the interplay between mixing entropy ΔS mixing and phase selection. Considering the large number of metals in the periodic table, the total number of possible HEA compositions is virtually unlimited.In addition to their structural and chemical diversity, HEAs can display novel, highly tunable properties such as, for example, excellent specific strength (6, 7), superior mechanical performance at high temperatures (8), and fracture toughness at cryogenic temperatures (9, 10), making them promising candidates for new applications. Simple niobium-titanium-based binary al...

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Discovery of a Superconducting High-Entropy Alloy

Cited by 431 publications

References 16 publications

Phonon broadening in high entropy alloys

Phonon broadening in high entropy alloys

Single-Phase Concentrated Solid-Solution Alloys: Bridging Intrinsic Transport Properties and Irradiation Resistance

Effect of electron count and chemical complexity in the Ta-Nb-Hf-Zr-Ti high-entropy alloy superconductor

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