Feature Papers in Entropic Alloys and Meta-Metals

A special issue of Metals (ISSN 2075-4701). This special issue belongs to the section "Entropic Alloys and Meta-Metals".

Deadline for manuscript submissions: 30 June 2024 | Viewed by 11771

Special Issue Editors

Beijing Advanced Innovation Center of Materials Genome Engineering, State Key Laboratory for Advanced Metals and Materials, University of Science and Technology Beijing, 30 XueyuanRoad, Beijing 100083, China
Interests: high-entropy materials and amorphous alloys; serration and noise in materials; meta-materials
Special Issues, Collections and Topics in MDPI journals
School of Materials Science and Engineering, Huazhong University of Science and Technology, Wuhan 430074, China
Interests: high-temperature material synthesis and manufacturing; energy and catalysis materials; micro- and nanomanufacturing; high-throughput and automated synthesis; data-driven intelligent manufacturing

Special Issue Information

Dear Colleagues,

We are pleased to announce that the Section “Entropic Alloys and Meta-Metals” is compiling a collection of papers submitted by our Section’s Editorial Board members and leading scholars in this field of research. We welcome contributions as well as recommendations from Editorial Board Members.

The aim of this Special Issue is to publish a set of papers that characterize the best original articles, including in-depth reviews of the state of the art and original and up-to-date contributions involving amorphous alloys and high- and/or medium-entropy alloys. Anything that brings innovative elements and is related to deeptech is welcome. We hope that these articles will be widely read and have a profound influence on the field. All articles in this Special Issue will be compiled in a print edition book after the deadline and will be appropriately promoted.

Topics of interest are all those involving advanced technologies and their applications in areas such as:

  • Amorphous alloys;
  • High-entropy alloys;
  • Medium-entropy alloys;
  • Machine learning;
  • Materials genome

Prof. Dr. Yong Zhang
Prof. Dr. Yonggang Yao
Guest Editors

Manuscript Submission Information

Manuscripts should be submitted online at www.mdpi.com by registering and logging in to this website. Once you are registered, click here to go to the submission form. Manuscripts can be submitted until the deadline. All submissions that pass pre-check are peer-reviewed. Accepted papers will be published continuously in the journal (as soon as accepted) and will be listed together on the special issue website. Research articles, review articles as well as short communications are invited. For planned papers, a title and short abstract (about 100 words) can be sent to the Editorial Office for announcement on this website.

Submitted manuscripts should not have been published previously, nor be under consideration for publication elsewhere (except conference proceedings papers). All manuscripts are thoroughly refereed through a single-blind peer-review process. A guide for authors and other relevant information for submission of manuscripts is available on the Instructions for Authors page. Metals is an international peer-reviewed open access monthly journal published by MDPI.

Please visit the Instructions for Authors page before submitting a manuscript. The Article Processing Charge (APC) for publication in this open access journal is 2600 CHF (Swiss Francs). Submitted papers should be well formatted and use good English. Authors may use MDPI's English editing service prior to publication or during author revisions.

Keywords

  • entropic alloys
  • high entropy alloys
  • high-throughput technology
  • amorphous alloys
  • bulk metallic glasses
  • lightweight alloys
  • single crystals
  • Bridgman solidification
  • high gravity effects
  • phase stability

Published Papers (8 papers)

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Research

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12 pages, 2235 KiB  
Article
Hot Deformation Behavior of Fe40Mn20Cr20Ni20 Medium-Entropy Alloy
by Zhen Wang, Qixin Ma, Zhouzhu Mao, Xikou He, Lei Zhao, Hongyan Che and Junwei Qiao
Metals 2024, 14(1), 32; https://doi.org/10.3390/met14010032 - 28 Dec 2023
Viewed by 689
Abstract
Fe40Mn20Cr20Ni20 medium-entropy alloy (MEA) has a single-phase crystal structure with high strength and good ductility at room temperature. It is important to study the hot deformation behavior for this alloy at a partially recrystallized state for [...] Read more.
Fe40Mn20Cr20Ni20 medium-entropy alloy (MEA) has a single-phase crystal structure with high strength and good ductility at room temperature. It is important to study the hot deformation behavior for this alloy at a partially recrystallized state for possible high-temperature applications. In this investigation, the tensile tests were conducted on sheet materials treated via cold rolling combined with annealing at strain rates of 1 × 10−3–1 × 10−1 s−1 and deformation temperatures of 573–873 K. And the hyperbolic sine model was used to study the relationship between the peak stress, deformation energy storage and Zener–Hollomon parameter (Z parameter) of Fe40Mn20Cr20Ni20 medium-entropy alloys under high-temperature tension. According to the Arrhenius-type model, the constitutive equation of the alloys based on the flow stress was constructed, and the deformation activation energy and material parameters under different strain conditions were obtained. Based on the power dissipation theory and the instability criterion of the dynamic material model, the power dissipation diagram and the instability diagram were constructed, and the hot working map with a strain of 0.1 was obtained. The results show that the hyperbolic sine relation between the peak stress and Zener–Hollomon parameters can be well satisfied, and the deformation activation energy Q is 242.51 KJ/mol. Finally, the excellent thermo-mechanical processing range is calculated based on the hot working map. The flow instability region is 620–700 K and the strain rate is 2 × 10−3–4 × 10−3 s−1, as well as in the range of 787–873 K and 2 × 10−3–2.73 × 10−2 s−1. The optimum thermo-mechanical window is 850–873 K, ε˙ = 1 × 10−3–2 × 10−3 s−1. Full article
(This article belongs to the Special Issue Feature Papers in Entropic Alloys and Meta-Metals)
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21 pages, 4160 KiB  
Article
Designing Quaternary and Quinary Refractory-Based High-Entropy Alloys: Statistical Analysis of Their Lattice Distortion, Mechanical, and Thermal Properties
by Saro San, Sahib Hasan, Puja Adhikari and Wai-Yim Ching
Metals 2023, 13(12), 1953; https://doi.org/10.3390/met13121953 - 29 Nov 2023
Cited by 1 | Viewed by 910
Abstract
The rapid evolution in materials science has resulted in a significant interest in high-entropy alloys (HEAs) for their unique properties. This study focuses on understanding both quaternary and quinary body-centered cubic (BCC) of 12 refractory-based HEAs, and on analysis of their electronic structures, [...] Read more.
The rapid evolution in materials science has resulted in a significant interest in high-entropy alloys (HEAs) for their unique properties. This study focuses on understanding both quaternary and quinary body-centered cubic (BCC) of 12 refractory-based HEAs, and on analysis of their electronic structures, lattice distortions, mechanical, and thermal properties. A comprehensive assessment is undertaken by means of density functional theory (DFT)-based first principles calculations. It is well known that multiple constituents lead to notable lattice distortions, especially in quinary HEAs. This distortion, in turn, has significant implications on the electronic structure that ultimately affect mechanical and thermal behaviors of these alloys such as ductility, lattice thermal conductivity, and toughness. Our in-depth analysis of their electronic structures revealed the role of valence electron concentration and its correlation with bond order and mechanical properties. Local lattice distortion (LD) was investigated for these 12 HEA models. M1 (WTiVZrHf), M7 (TiZrHfW), and M12 (TiZrHfVNb) have the highest LD whereas the models M3 (MoTaTiV), M5 (WTaCrV), M6 (MoNbTaW), and M9 (NbTaTiV) have the less LD. Furthermore, we investigated the thermal properties focusing on Debye temperature (ΘD), thermal conductivity (κ), Grüneisen parameter (γα), and dominant phonon wavelength (λdom). The NbTaTiV(M9) and TiVNbHf(M10) models have significantly reduced lattice thermal conductivities (κL). This reduction is due to the mass increase and strain fluctuations, which in turn signify lattice distortion. The findings not only provide an understanding of these promising materials but also offer guidance for the design of next-generation HEAs with properties tailored for potential specific applications. Full article
(This article belongs to the Special Issue Feature Papers in Entropic Alloys and Meta-Metals)
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14 pages, 14901 KiB  
Article
Hot Rolling on Microstructure and Properties of NbHfTiVC0.1 Refractory High-Entropy Alloy
by Haochen Qiu, Shutian Tao, Wei Jiang, Xuehui Yan, Shuaishuai Wu, Shengli Guo, Baohong Zhu and Dongxin Wang
Metals 2023, 13(11), 1909; https://doi.org/10.3390/met13111909 - 20 Nov 2023
Viewed by 772
Abstract
NbHfTiVC0.1 refractory high-entropy alloy (RHEA) exhibits excellent comprehensive mechanical properties and demonstrates great potential for applications. However, the mechanical properties need to be improved further. In this work, hot rolling on NbHfTiVC0.1 RHEA at temperatures of 650 °C, 850 °C, and [...] Read more.
NbHfTiVC0.1 refractory high-entropy alloy (RHEA) exhibits excellent comprehensive mechanical properties and demonstrates great potential for applications. However, the mechanical properties need to be improved further. In this work, hot rolling on NbHfTiVC0.1 RHEA at temperatures of 650 °C, 850 °C, and 1050 °C, with total reductions of up to 30%, 50%, 70%, and 80%, was conducted. The microstructure and mechanical property evolution of the samples were further investigated. The hot-rolled samples at 650 °C and 850 °C exhibit a composition consisting of BCC, carbide, and Laves phases, whereas the samples rolled at 1050 °C only consist of BCC and carbide phases. The 650-80 sample displays the highest ultimate tensile strength (1354 MPa), and the 1050-80 sample demonstrates the highest elongation (16%). The highest strength observed in the 650 °C-80% sample can be attributed to the presence of fractured and refined carbides, fine-grains, and the hindrance of dislocation slip by the fine Laves phase. At a higher rolling temperature (1050 °C), the Laves phase disappears, resulting in a reduction in strength but an increase in plasticity. Furthermore, the dislocation slipping mechanism within the BCC matrix also contributes positively to plastic deformation, leading to a notable increase in ductility for the 1050 °C-80% sample. These research findings provide valuable insights into enhancing the strength and ductility simultaneously of NbHfTiVC0.1 RHEA through hot rolling. Full article
(This article belongs to the Special Issue Feature Papers in Entropic Alloys and Meta-Metals)
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16 pages, 3464 KiB  
Article
Tuning Non-Isothermal Crystallization Kinetics between Fe20Co20Ni20Cr20(P0.45B0.2C0.35)20 High-Entropy Metallic Glass and the Predecessor Fe75Cr5P9B4C7 Metallic Glass
by Tao Xu, Jiansheng Yao, Longchao Zhuo and Ziqi Jie
Metals 2023, 13(9), 1624; https://doi.org/10.3390/met13091624 - 20 Sep 2023
Cited by 2 | Viewed by 611
Abstract
In the present work, comparisons of non-isothermal crystallization kinetics between Fe20Co20Ni20Cr20(P0.45B0.2C0.35)20 high-entropy metallic glass (HEMG) and the predecessor Fe75Cr5P9B4C7 [...] Read more.
In the present work, comparisons of non-isothermal crystallization kinetics between Fe20Co20Ni20Cr20(P0.45B0.2C0.35)20 high-entropy metallic glass (HEMG) and the predecessor Fe75Cr5P9B4C7 metallic glass (MG) were performed with X-ray diffraction and differential scanning calorimetry approaches. The HEMG possesses a harsher crystallization process compared with the predecessor MG, deriving from a higher triggering energy for all the characteristic transitions and local activation energy along with a smaller local Avrami exponent and a growth with pre-existing nuclei. Meanwhile, the glass transition is the easiest process, but the nucleation of the second crystallization case is the hardest transition for the HEMG. However, the predecessor MG possesses distinctly different crystallization features of a moderate difficulty for the glass transition, the harshest process for the growth transition of the second crystallization case, and a crystallization of growth with a diverse nucleation rate. These results conclusively prove that the non-isothermal crystallization kinetics can be significantly changed after the present high-entropy alloying with the substitution of similar solvent elements Co, Ni, and Cr with Fe in Fe75Cr5P9B4C7 MG. Moreover, the two alloys possess a strong glassy formation melt with high thermal stability and diverse crystallized products after non-isothermal crystallization. Full article
(This article belongs to the Special Issue Feature Papers in Entropic Alloys and Meta-Metals)
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11 pages, 8357 KiB  
Article
Fatigue Behavior of Cu-Zr Metallic Glasses under Cyclic Loading
by Nikolai V. Priezjev
Metals 2023, 13(9), 1606; https://doi.org/10.3390/met13091606 - 17 Sep 2023
Viewed by 925
Abstract
The effect of oscillatory shear deformation on the fatigue life, yielding transition, and flow localization in metallic glasses is investigated using molecular dynamics simulations. We study a well-annealed Cu-Zr amorphous alloy subjected to periodic shear at room temperature. We find that upon loading [...] Read more.
The effect of oscillatory shear deformation on the fatigue life, yielding transition, and flow localization in metallic glasses is investigated using molecular dynamics simulations. We study a well-annealed Cu-Zr amorphous alloy subjected to periodic shear at room temperature. We find that upon loading for hundreds of cycles at strain amplitudes just below a critical value, the potential energy at zero strain remains nearly constant and plastic events are highly localized. By contrast, at strain amplitudes above the critical point, the plastic deformation is gradually accumulated upon continued loading until the yielding transition and the formation of a shear band across the entire system. Interestingly, when the strain amplitude approaches the critical value from above, the number of cycles to failure increases as a power-law function, which is consistent with the previous results on binary Lennard-Jones glasses. Full article
(This article belongs to the Special Issue Feature Papers in Entropic Alloys and Meta-Metals)
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19 pages, 4766 KiB  
Article
Temperature and Crystalline Orientation-Dependent Plastic Deformation of FeNiCrCoMn High-Entropy Alloy by Molecular Dynamics Simulation
by Fuan Yang, Jun Cai, Yong Zhang and Junpin Lin
Metals 2022, 12(12), 2138; https://doi.org/10.3390/met12122138 - 13 Dec 2022
Cited by 2 | Viewed by 1376
Abstract
The effect of the crystallographic direction and temperature on the mechanical properties of an FeNiCrCoMn high-entropy alloy (HEA) is explored by molecular dynamics simulations. The calculated static properties are in agreement with the respective experimental/early theoretical results. The calculated compressive yield stress along [...] Read more.
The effect of the crystallographic direction and temperature on the mechanical properties of an FeNiCrCoMn high-entropy alloy (HEA) is explored by molecular dynamics simulations. The calculated static properties are in agreement with the respective experimental/early theoretical results. The calculated compressive yield stress along the <010> direction of a single crystal/polycrystal is the same in order of magnitude as the experimental results. The yield stress and Young’s modulus of the single crystal show strong anisotropy. Unlike the single crystal, the polycrystal behaves as an isotropic and has strong ductility. It is found that the dislocations produced in the plastic deformation process of the HEA are mainly 1/6<112> Shockley dislocations. The dislocations produced under normal stress loads are far more than that in the shearing process. FCC transformation into HCP does not occur almost until yield stress appears. The yield stress, yield strain, and Young’s modulus reduce gradually with increasing temperature. The modulus of the single/double crystal under compressive and tensile loads presents an obvious asymmetry, while there is only a small difference in the polycrystal. The strain point is found to be the same for stress yielding, FCC-HCP phase transition, and dislocation density, varying from slow to fast with strain at the considered temperature. Full article
(This article belongs to the Special Issue Feature Papers in Entropic Alloys and Meta-Metals)
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Review

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23 pages, 5705 KiB  
Review
Corrosion-Resistant Coating Based on High-Entropy Alloys
by Cheng Lin and Yonggang Yao
Metals 2023, 13(2), 205; https://doi.org/10.3390/met13020205 - 20 Jan 2023
Cited by 7 | Viewed by 3670
Abstract
Metal corrosion leads to serious resource waste and economic losses, and in severe cases, it can result in catastrophic safety incidents. As a result, proper coatings are often employed to separate metal alloys from the ambient environment and thus prevent or at least [...] Read more.
Metal corrosion leads to serious resource waste and economic losses, and in severe cases, it can result in catastrophic safety incidents. As a result, proper coatings are often employed to separate metal alloys from the ambient environment and thus prevent or at least slow down corrosion. Among various materials, high-entropy alloy coatings (HEA coating) have recently received a lot of attention due to their unique entropy-stabilized structure, superior physical and chemical properties, and often excellent corrosion resistance. To address the recent developments and remaining issues in HEA coatings, this paper reviews the primary fabrication methods and various elemental compositions in HEA coatings and highlights their effects on corrosion resistance properties. It is found that FeCoCrNi-based and refractory high-entropy alloy coatings prepared by the laser/plasma cladding method typically show better corrosion resistance. It also briefly discusses the future directions toward high-performing corrosion-resistant coatings based on HEA design. Full article
(This article belongs to the Special Issue Feature Papers in Entropic Alloys and Meta-Metals)
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13 pages, 3749 KiB  
Review
Cryogenic-Mechanical Properties and Applications of Multiple-Basis-Element Alloys
by Kaixuan Cui, Peter K. Liaw and Yong Zhang
Metals 2022, 12(12), 2075; https://doi.org/10.3390/met12122075 - 02 Dec 2022
Cited by 19 | Viewed by 1965
Abstract
Multiple-basis-element (MBE) alloy was defined as the entropy of mixing over 1R (R is the gas constant, 8.31 J/k), and contains at least three principal elements, each one at over 5%. Thus, MBE alloys can include high-entropy alloys (HEAs), medium-entropy alloys (MEAs), amorphous [...] Read more.
Multiple-basis-element (MBE) alloy was defined as the entropy of mixing over 1R (R is the gas constant, 8.31 J/k), and contains at least three principal elements, each one at over 5%. Thus, MBE alloys can include high-entropy alloys (HEAs), medium-entropy alloys (MEAs), amorphous alloys, and some martensite stainless steels, which have been reported to possess excellent cryogenic properties. This paper reviews the progress of the cryogenic-mechanical properties and applications of MBE alloys. It has been concluded that, with the increase of entropy, the ductile-brittle-transition temperatures (DBTT) can be decreased to the liquid helium temperature (4.2 K). In summary, the cryogenic toughness of MBE alloys can be greatly enhanced by entropy adjustments, which is beneficial to their application at low temperatures. Full article
(This article belongs to the Special Issue Feature Papers in Entropic Alloys and Meta-Metals)
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