Science and technology in high-entropy alloys

Zhang, Weiran; Liaw, Peter K.; Zhang, Yong

doi:10.1007/s40843-017-9195-8

Cited by 784 publications

(283 citation statements)

References 147 publications

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“…A concept of mixing of 5 or more elements in equimolar or near equimolar concentrations is used in order to explore central regions of multicomponent alloy phase space [1]. This approach is driven by possibility to get stable solid solution microstructure of the alloy with favourable mechanical properties (high strength and good ductility) as well as other physical properties, for example, good corrosion resistance [2]. Microstructure stability shall be provided by high configurational entropy of the system, supposing random arrangement of alloying elements [3,4].…”

Section: Introductionmentioning

confidence: 99%

Microstructure and Room Temperature Mechanical Properties of Different 3 and 4 Element Medium Entropy Alloys from HfNbTaTiZr System

Zýka

Málek

Veselý

et al. 2019

Entropy

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Refractory high entropy alloys (HEA) are promising materials for high temperature applications. This work presents investigations of the room temperature tensile mechanical properties of selected 3 and 4 elements medium entropy alloys (MEA) derived from the HfNbTaTiZr system. Tensile testing was combined with fractographic and microstructure analysis, using scanning electron microscope (SEM), wavelength dispersive spectroscope (WDS) and X-Ray powder diffraction (XRD). The 5 element HEA alloy HfNbTaTiZr exhibits the best combination of strength and elongation while 4 and 3 element MEAs have lower strength. Some of them are ductile, some of them brittle, depending on microstructure. Simultaneous presence of Ta and Zr in the alloy resulted in a significant reduction of ductility caused by reduction of the BCC phase content. Precipitation of Ta rich particles on grain boundaries reduces further the maximum elongation to failure down to zero values.Entropy 2019, 21, 114 2 of 17 Different elements are used to fabricate HEAs. Although the number of possible 4 or 5 elements combinations is enormous five basic metallic HEA groups can be distinguished: FCC HEAs based on the Cantor alloy, BCC refractory metal HEAs, light element HEAs, HCP HEAs and precious functional HEAs [7]. Ceramic HEAs have been established as well [8,9].Our attention was attracted by the refractory HEA group, which is composed of elements from IV, V and VI groups of the periodic table of elements [10]. These elements are characterized by prevailing good mutual miscibility and high melting points. The melting point of titanium (1668 • C) is the lowest among them. Therefore HEAs composed of these elements are intended for high temperature applications. Moreover some of these elements are biocompatible [11]. Therefore some of these alloys can be attractive for bioimplant related materials research. Note that β-Ti alloys used in bioimplant research are usually composed of this group of elements [12]. Several biocompatible HEAs have been already studied [13][14][15][16]. Also, hard ceramic composites were produced from the metals from IV, V and VI groups of the periodic table [17].Original definition of HEAs with single phase solid solution microstructure and good room temperature mechanical properties, especially ductility, is beneficial also for use in human medicine. Inspiration can be found also in other materials used for production of bioimplants which are used or have been used in other parts of material research, for example, TiAl6V4 in aerospace, CoCrMo in aero engines.Our first attempt in research of HEAs was therefore related to HfNbTaTiZr refractory metal alloy [18]. Our research was inspired by Senkov [19] and confirmed our expectations. Ingots produced by vacuum arc melting possessed single phase solid solution microstructure, with a high room temperature tensile strength and ductility.Some of the elements used in the HfNbTaTiZr alloy are very similar to each other with very similar chemical behaviour; Nb is chemically similar to Ta and Zr to ...

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Section: Introductionmentioning

confidence: 99%

Microstructure and Room Temperature Mechanical Properties of Different 3 and 4 Element Medium Entropy Alloys from HfNbTaTiZr System

Zýka

Málek

Veselý

et al. 2019

Entropy

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“…A particularly interesting test-case of such multi-principal element alloys are highentropy alloys (HEAs) when they are based on different elements and constitute a single phase with solid solution 64 . Alloying is a well-known technique to reduce the thermal conductivity, and the HEA concept has therefore been used to minimize thermal conductivity in several studies, often with an emphasis to develop novel thermoelectric materials 65 .…”

Section: Alloys -Using High Entropy Alloys As a Test Casementioning

confidence: 99%

Machine Learning for Novel Thermal-Materials Discovery: Early Successes, Opportunities, and Challenges

Zhang¹,

Hippalgaonkar²,

Buonassisi³

et al. 2018

ES Energy Environ.

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High-throughput computational and experimental design of materials aided by machine learning have become an increasingly important field in material science. This area of research has emerged in leaps and bounds in the thermal sciences, in part due to the advances in computational and experimental methods in obtaining thermal properties of materials. In this paper, we provide a current overview of some of the recent work and highlight the challenges and opportunities that are ahead of us in this field. In particular, we focus on the use of machine learning and high-throughput methods for screening of thermal conductivity for compounds, composites and alloys as well as interfacial thermal conductance. These new tools have brought about a feedback mechanism for understanding new correlations and identifying new descriptors, speeding up the discovery of novel thermal functional materials.

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“…Compared with the traditional alloys with one or two principal matrix elements, high entropy alloys (HEAs) are composed of multiple elements [1]. The ratio of component elements has transformed from equal atom ratio to unequal atom ratio compositions, and the phase compositions of HEAs have also gradually transited from single-phase solid solution to multi-phase alloys [2]. The HEAs usually have excellent performance, such as excellent ductility [3], high strength [4], corrosion resistance [5], and radiation resistance [6].…”

Section: Introductionmentioning

confidence: 99%

A new single crystal high entropy alloy with excellent high-temperature tensile property

Chen

Yuan

Ren

et al. 2020

Mater. Res. Express

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A new single crystal high entropy alloy is developed and produced using Bridgman directionalsolidification and seed-crystal method. The microstructure exhibits the directional dendrite morphology and is mainly composed of the FCC matrix and the L1 2 ordered precipitates. Its hightemperature yield strengths are far higher than those of the first-generation single crystal superalloys, and close to those of the second-generation ones. The solid-solution strengthening effect from the high content of W and Mo, as well as the precipitation strengthening effect from the combined addition of Al, Ti, Ta, and Nb, should be responsible for the excellent high-temperature strength of the investigated alloy.

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Science and technology in high-entropy alloys

Cited by 784 publications

References 147 publications

Microstructure and Room Temperature Mechanical Properties of Different 3 and 4 Element Medium Entropy Alloys from HfNbTaTiZr System

Microstructure and Room Temperature Mechanical Properties of Different 3 and 4 Element Medium Entropy Alloys from HfNbTaTiZr System

Machine Learning for Novel Thermal-Materials Discovery: Early Successes, Opportunities, and Challenges

A new single crystal high entropy alloy with excellent high-temperature tensile property

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