Nanocrystalline High-Entropy Alloys: A New Paradigm in High-Temperature Strength and Stability

Zou, Yu; Wheeler, Jeffrey M.; Ma, Huan; Okle, Philipp; Spolenak, Ralph

doi:10.1021/acs.nanolett.6b04716

Cited by 158 publications

(55 citation statements)

References 40 publications

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“…Refractory HEAs [27] are a category of emerging multi- component alloys, showing superior mechanical properties at elevated temperatures which is important for application [33,95]. The NbMoTaW alloy has better performance retention than the refractory metal tungsten after a heat exposure at 1,373 K for 3 days [33].…”

Section: Thermal Stabilitymentioning

confidence: 99%

Science and technology in high-entropy alloys

2018

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As human improve their ability to fabricate materials, alloys have evolved from simple to complex compositions, accordingly improving functions and performances, promoting the advancements of human civilization. In recent years, high-entropy alloys (HEAs) have attracted tremendous attention in various fields. With multiple principal components, they inherently possess unique microstructures and many impressive properties, such as high strength and hardness, excellent corrosion resistance, thermal stability, fatigue, fracture, and irradiation resistance, in terms of which they overwhelm the traditional alloys. All these properties have endowed HEAs with many promising potential applications. An in-depth understanding of the essence of HEAs is important to further developing numerous HEAs with better properties and performance in the future. In this paper, we review the recent development of HEAs, and summarize their preparation methods, composition design, phase formation and microstructures, various properties, and modeling and simulation calculations. In addition, the future trends and prospects of HEAs are put forward.

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Section: Thermal Stabilitymentioning

confidence: 99%

Science and technology in high-entropy alloys

2018

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“…The powder particles showed high hardness of 7.5 GPa, which was previously reached only by annealing of rapidly quenched material. This indicates the importance of the high interface density within the material 4…”

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confidence: 99%

Early stage phase separation of AlCoCr0.75Cu0.5FeNi high-entropy powder at the nanoscale

Peter

Duarte

Liebscher

et al. 2020

Journal of Alloys and Compounds

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High entropy alloys are generally considered to be single phase material. This state is, however, typically a non-equilibrium state after fabrication at high cooling rates. Phase constitution after fabrication or heat treatment is mostly known for isothermal annealing only and for casts as well as rapidly quenched alloys. Knowledge on early phase separation stages of high entropy alloys and their mechanisms are missing so far. Here, we present results on phase separation at intermediate cooling rates, by characterization of gas atomized powder of the AlCoCr 0.75 Cu 0.5 FeNi alloy. Although investigation by X-ray diffraction and Electron Backscatter Diffraction indicates a single-phase nature of the powder particles, aberrationcorrected scanning transmission electron microscopy and atom probe tomography reveal a nanoscale phase separation into Ni-Al-rich B2 and Fe-Cr-rich A2 regions as well as a high number density of 3.1x10 24 Cu-rich clusters per m 3 in the B2 matrix. The observed phase separation and cluster formation are linked to spinodal decomposition and nucleation processes, respectively. The study highlights that adequate characterization techniques need to be chosen when making statements about phase stability and structural evolution in compositionally complex alloys.

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“…However, it is possible to retain the potential properties of NC materials at higher temperatures by utilizing the HEA design concept. Zou et al [101] produced a stable NC NbMoTaW HEA with columnar grains of %70-100 nm grain size and demonstrated the retention of high yield strength of %5 GPa up to 600 C. The NC NbMoTaW HEA exhibited consistent strain rate sensitivity of %0.005 from room temperature to 600 C. The alloy has very high strength to density ratios and strength normalized by shear modulus than any other reported studies on NC metals at the same homologous temperature. Zhou et al [53] utilized the concept of reducing the Figure 2).…”

Section: Introductionmentioning

confidence: 97%

“…Zou et al [101] fabricated a refractory NC columnar NbMoTaW HEA and demonstrated the strength retention up to 600 C. The yield strength of NC HEA decreased from 7 GPa at room temperature to 5 GPa at 600 C, while the single crystal HEA decreased from 2 GPa at room temperature to 1 GPa at 600 C . The NC HEA showed strength reduction of only 20% while the strength reduction in coarse grain HEA is 50%.…”

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confidence: 99%

High‐Entropy Alloys: Potential Candidates for High‐Temperature Applications – An Overview

2017

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Multi-principal elemental alloys, commonly referred to as high-entropy alloys (HEAs), are a new class of emerging advanced materials with novel alloy design concept. Unlike the design of conventional alloys, which is based on one or at most two principal elements, the design of HEA is based on multi-principal elements in equal or near-equal atomic ratio. The advent of HEA has revived the alloy design perception and paved the way to produce an ample number of compositions with different combinations of promising properties for a variety of structural applications. Among the properties possessed by HEAs, sluggish diffusion and strength retention at elevated temperature have caught wide attention. The need to develop new materials for high-temperature applications with superior high-temperature properties over superalloys has been one of the prime concerns of the high-temperature materials research community. The current article shows that HEAs have the potential to replace Ni-base superalloys as the next generation hightemperature materials. This review focuses on the phase stability, microstructural stability, and high-temperature mechanical properties of HEAs. This article will be highly beneficial for materials science and engineering community whose interest is in the development and understanding of HEAs for high-temperature applications.

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Nanocrystalline High-Entropy Alloys: A New Paradigm in High-Temperature Strength and Stability

Cited by 158 publications

References 40 publications

Science and technology in high-entropy alloys

Science and technology in high-entropy alloys

Early stage phase separation of AlCoCr0.75Cu0.5FeNi high-entropy powder at the nanoscale

High‐Entropy Alloys: Potential Candidates for High‐Temperature Applications – An Overview

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