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New Insights of High Entropy Alloys and Its Applications
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New Insights of High Entropy Alloys and Its Applications

A special issue of Coatings (ISSN 2079-6412). This special issue belongs to the section "Corrosion, Wear and Erosion".

Deadline for manuscript submissions: closed (30 November 2023) | Viewed by 3173

Special Issue Editor

Dr. Amalraj Marshal

E-Mail Website
Guest Editor
Fakultät Maschinenbau, Institut für Werkstoffe, Ruhr-University, Bochum, Germany
Interests: combinatorial synthesis; high throughput characterization; thin films and hard coatings; soft magnetic materials; composition–structure–property relation; high-entropy alloys; atom probe tomography; corelative microscopy

Special Issue Information

Dear Colleagues,

High-entropy alloys (HEA) have gained great interest and extensive research due to their unconventional alloy design strategy comprising multiple principal elements. Some of them possess unusual and tailorable mechanical properties, namely, excellent toughness at cryogenic temperatures, a concurrent increase in strength and ductility, and promising functional properties. HEA as films and ceramics have attracted equal attention too, with some outclassing the conventional ones as coatings for demanding environments. The multi-element composition window that could be explored is limitless and with the advent of coating and film technology, the time and material (and cost) usage are significantly reduced, facilitating rapid material exploration and discovery.

This Special Issue aims to provide a rapid and comprehensive communication platform for presenting the latest findings on the design, synthesis, characterization, and property correlation of HE alloys and ceramics as thick/thin films.  We encourage the communication of work involving novel multicomponent compositions, applications targeting energy conversion, surfaces and interfaces, high-throughput experimentation, and computational techniques that help produce fundamental insights into HEA.

We welcome short communications, full-length pieces, and review articles in this Special Issue.

Dr. Amalraj Marshal
Guest Editor

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. Coatings 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

  • high-entropy alloy
  • thin films and hard coatings
  • synthesis and characterization
  • microstructure
  • mechanical and functional properties

Published Papers (3 papers)

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Research

14 pages, 1840 KiB  
Article
Strategic Selection of Refractory High-Entropy Alloy Coatings for Hot-Forging Dies by Applying Decision Science
by Tanjore V. Jayaraman and Ramachandra Canumalla
Coatings 2024, 14(1), 19; https://doi.org/10.3390/coatings14010019 - 24 Dec 2023
Cited by 1 | Viewed by 974
Abstract
We compiled, assessed, and ranked refractory high-entropy alloys (RHEAs) from the existing literature to identify promising coating materials for hot-forging dies. The selection methodology was rigorously guided by decision science principles, seamlessly integrating multiple attribute decision making (MADM), principal component analysis (PCA), and [...] Read more.
We compiled, assessed, and ranked refractory high-entropy alloys (RHEAs) from the existing literature to identify promising coating materials for hot-forging dies. The selection methodology was rigorously guided by decision science principles, seamlessly integrating multiple attribute decision making (MADM), principal component analysis (PCA), and hierarchical clustering (HC). By employing a combination of twelve diverse MADM methods, we successfully ranked a total of 22 RHEAs. This analytical technique unveiled the top five RHEAs: Ti20-Zr20-Hf20-Nb20-Cr20, Al20.4-Mo10.5-Nb22.4-Ta10.1-Ti17.8-Zr18.8, Ti20-Zr20-Hf20-Nb20-V20, Al11.3-Nb22.3-Ta13.1-Ti27.9-V4.5-Zr20.9, and Al7.9-Hf12.8-Nb23-Ta16.8-Ti18.9-Zr20.6 pertinent for generating data on other significant properties, including wear resistance, fatigue (both thermal and mechanical), bonding compatibility with the substrate die material, oxidation resistance, potential reactions with the workpiece, cost-effectiveness, fabricability, and more. The three highest-ranked RHEAs share key characteristics, including a body-centered cubic (BCC) crystal structure, thermal conductivity below ~70 W/mK, and impressive yield strength at ambient and elevated temperatures, surpassing 1100 MPa. Moreover, they exhibit a remarkable ~73% similarity among themselves. The decision science-driven analyses yield sound metallurgical insights and provide valuable guidelines for developing RHEA coatings tailored for hot-forging dies. The strategy for designing RHEA-based coating materials for hot-forging dies should focus on compositions featuring a substantial presence of refractory metals while maintaining a BCC crystal structure. This combination is likely to deliver the desired blend of thermal and mechanical properties, rendering these coatings exceptionally well-suited for the demanding requirements of hot-forging operations. Full article
(This article belongs to the Special Issue New Insights of High Entropy Alloys and Its Applications)
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14 pages, 4021 KiB  
Article
Deformation Behavior and Processing Map of AlCoCrFeNiTi0.5 High-Entropy Alloy at High Temperature
by Xinbin Liu, Tiansheng Li, Yong Wang, Xianghua Kong and Chenyang Zhao
Coatings 2023, 13(10), 1811; https://doi.org/10.3390/coatings13101811 - 22 Oct 2023
Viewed by 865
Abstract
AlCoCrFeNiTi0.5 high-entropy alloy (HEA) shows excellent properties in hardness and corrosion resistance. AlCoCrFeNiTi0.5 HEA was prepared using a non-consumable vacuum arc furnace. Hot-deformation behavior of AlCoCrFeNiTi0.5 HEA was explored under 1073–1373 K with a strain rate between 0.001 and 1 [...] Read more.
AlCoCrFeNiTi0.5 high-entropy alloy (HEA) shows excellent properties in hardness and corrosion resistance. AlCoCrFeNiTi0.5 HEA was prepared using a non-consumable vacuum arc furnace. Hot-deformation behavior of AlCoCrFeNiTi0.5 HEA was explored under 1073–1373 K with a strain rate between 0.001 and 1 s−1 using a Gleeble-3800 thermomechanical simulator. The constitutive equation was established using the Arrhenius model, and the deformation activation energy and material constant were obtained. The processing map of HEA within 0.3–0.6 deformation was drawn according to dynamic material model (DMM). The results show that the hot-deformation process of HEA is dominated by work hardening combined with dynamic recovery, and dynamic recrystallization. The flow stress of HEA is significantly affected by deformation temperature and strain rate. The constitutive equation was constructed and verified, and the correlation coefficient of R2 = 0.9873 indicated that the constitutive equation can be used to accurately predict the flow stress of HEA. The processing map of HEA shows that the optimal hot-working process parameters are in the range of temperature 1150–1300 K and strain rate 0.002–0.05 s−1. This work will provide theoretical guidance for the hot-processing of HEA, which effectively promotes the application of the HEA in industry. Full article
(This article belongs to the Special Issue New Insights of High Entropy Alloys and Its Applications)
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13 pages, 4382 KiB  
Article
Microstructure, Mechanical Property, and Wear Behavior of NiAl-Based High-Entropy Alloy
by Ziyan Li, Xiaohong Wang, Yanyan Huang, Zhixin Xu, Yulei Deng, Xiaoying Jiang and Xiaohong Yang
Coatings 2023, 13(10), 1737; https://doi.org/10.3390/coatings13101737 - 06 Oct 2023
Cited by 1 | Viewed by 1010
Abstract
Based on the excellent comprehensive mechanical properties of high–entropy alloy (HEA), the NiAl-based HEA was designed to achieve excellent high-temperature strength, toughness, and wear resistance. In this work, vacuum arc melting technology was used to prepare (NiA1)78(CoCrFe)16.5Cu5.5 HEA, [...] Read more.
Based on the excellent comprehensive mechanical properties of high–entropy alloy (HEA), the NiAl-based HEA was designed to achieve excellent high-temperature strength, toughness, and wear resistance. In this work, vacuum arc melting technology was used to prepare (NiA1)78(CoCrFe)16.5Cu5.5 HEA, and its microstructure, phase composition, and mechanical properties were systematically studied. The results showed that (NiA1)78(CoCrFe)16.5Cu5.5 HEA was composed of FCC and BCC/B2, with a spinodal decomposition structure in the matrix, and nano-precipitation in the interdendritic, exhibiting a good high-temperature performance. At 600 °C, the compressive fracture strength is 842.5 MPa and the fracture strain is 24.5%. When the temperature reaches 800 °C, even if the strain reaches 50%, the alloy will not fracture, and the stress–strain curve shows typical work hardening and softening characteristics. The wear coefficient of the alloy first increases and then decreases with the increase in temperature in the range of room temperature to 400 °C. However, the specific wear rate shows the opposite trend. At 100 °C, the wear rate reaches the lowest of 7.05 × 10−5 mm3/Nm, and the wear mechanism is mainly abrasive wear. Full article
(This article belongs to the Special Issue New Insights of High Entropy Alloys and Its Applications)
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