Advanced High-Entropy Materials and Coatings

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

Deadline for manuscript submissions: closed (20 May 2024) | Viewed by 19389

Special Issue Editor

College of Materials Science and Engineering, Hunan University, Changsha 410082, China
Interests: high-entropy alloy; corrosion behavior; costings; electrochemical testing; anti-bacterial properties; biomedical materia

Special Issue Information

Dear Colleagues,

The “high-entropy” design concept originating from multi-principal-element solid solutions has attracted intense interest from academia and industries worldwide. Recently, significant progress in the metal community has led to the development of various other types of high-entropy materials (HEMs), such as high-entropy metallic glasses, high-entropy ceramics, high-entropy thermoelectric materials, etc. The various HEMs that act as coatings have shown great potential for structural and functional applications based on their stability, corrosion resistance, and excellent mechanical properties. Different technologies have been adopted to fabricate HEM coatings, including sputtering, electrodeposition, spraying, laser cladding, plasma-transferred arc cladding, etc.

We are pleased to invite you to submit your work to this Special Issue on “Advanced High-Entropy Materials and Coatings”. This Special Issue aims to present theoretical and experimental articles addressing the current understandings, new development, and challenges on the synthesis of HEM coatings, studies of properties, as well as potential applications.

In this Special Issue, original research articles and reviews are welcome. Research areas may include (but not limited to) the following:

  • Coating technologies;
  • Composition design;
  • Surface characterization;
  • Corrosion;
  • Thermal stability;
  • Hardening and strengthening;
  • Applications.

We look forward to receiving your contributions.

Dr. Yunzhu Shi
Guest Editor

Manuscript Submission Information

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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.

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Keywords

  • high-entropy materials
  • microstructures
  • thin films
  • mechanical property
  • corrosion
  • oxidation
  • modeling

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Published Papers (7 papers)

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Research

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12 pages, 5843 KiB  
Article
Influence of the Gas Flow Rate on the Crack Formation of AlCoCrNi High-Entropy Metallic Film Fabricated Using Magnetron Sputtering
by Young-Soon Kim, Hae-Jin Park, Young-Seok Kim, Sung-Hwan Hong and Ki-Buem Kim
Coatings 2024, 14(1), 144; https://doi.org/10.3390/coatings14010144 - 21 Jan 2024
Cited by 1 | Viewed by 1374
Abstract
In the present study, the AlCoCrNi high-entropy metallic film was deposited on a Si wafer using a magnetron sputtering system. To capture the effects of the sputtering parameters on the microstructure and mechanical properties of the film, the flow rate of Ar gas [...] Read more.
In the present study, the AlCoCrNi high-entropy metallic film was deposited on a Si wafer using a magnetron sputtering system. To capture the effects of the sputtering parameters on the microstructure and mechanical properties of the film, the flow rate of Ar gas injected into the chamber (5, 7, and 8 sccm) was controlled. All films were identified as being of BCC phase with compositions of near equiatomic proportions, regardless of the gas flow rates. Nano-scale clusters were observed on the surfaces of all films, and nano-cracks were found in the film deposited at the Ar gas flow rate of 8 sccm, unlike the films deposited at the gas flow rates of 5 and 7 sccm. Detailed microstructural analysis of film deposition at an Ar gas flow rate of 8 sccm indicated that the void boundaries contribute to the formation of nano-cracks. The nano-indentation results indicated that the Ar gas flow rate 5 sccm specimen, with the smallest cluster size at the topmost surface, showed the highest hardness (12.21 ± 1.05 GPa) and Young’s modulus (188.1 ± 11 GPa) values. Full article
(This article belongs to the Special Issue Advanced High-Entropy Materials and Coatings)
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11 pages, 23271 KiB  
Article
Enhanced Corrosion−Resistance of AlTiCrFeMoSi High−Entropy Alloy Coating by Magnetron Sputtering
by Li Zhang, Yunzhu Shi, Qilu Ye and Bin Yang
Coatings 2023, 13(2), 332; https://doi.org/10.3390/coatings13020332 - 1 Feb 2023
Cited by 6 | Viewed by 1747
Abstract
The amorphous AlTiCrFeMoSi high entropy alloy (HEA) coating with high hardness (11.88 GPa) is successfully deposited on T91 substrate by the magnetron sputtering method. Both T91 steel and as−deposited AlTiCrFeMoSi coating samples are exposed to a static liquid lead−bismuth eutectic (LBE) at 550 [...] Read more.
The amorphous AlTiCrFeMoSi high entropy alloy (HEA) coating with high hardness (11.88 GPa) is successfully deposited on T91 substrate by the magnetron sputtering method. Both T91 steel and as−deposited AlTiCrFeMoSi coating samples are exposed to a static liquid lead−bismuth eutectic (LBE) at 550 °C for up to 2000 h. The coating exhibits excellent corrosion resistance against lead−bismuth eutectic (LBE) compared with the uncoated T91 steel. The results show that the AlTiCrFeMoSi HEA coating has great potential in LBE−cooled fast reactor application. Full article
(This article belongs to the Special Issue Advanced High-Entropy Materials and Coatings)
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11 pages, 4322 KiB  
Article
Effects of Ultrasonic Shot Peening on the Corrosion Resistance and Antibacterial Properties of Al0.3Cu0.5CoCrFeNi High-Entropy Alloys
by Xudong Chen, Tianyu Cui, Shengyu He, Weiwei Chang, Yunzhu Shi and Yuntian Lou
Coatings 2023, 13(2), 246; https://doi.org/10.3390/coatings13020246 - 20 Jan 2023
Cited by 5 | Viewed by 1461
Abstract
Cu-bearing high-entropy alloys (HEAs) have been proposed for use as structural materials in the marine environment due to their superior mechanical and antimicrobial properties. However, the Al, Cu-enriched precipitations in HEAs damage their corrosion resistance. In this study, we used ultrasonic shot peening [...] Read more.
Cu-bearing high-entropy alloys (HEAs) have been proposed for use as structural materials in the marine environment due to their superior mechanical and antimicrobial properties. However, the Al, Cu-enriched precipitations in HEAs damage their corrosion resistance. In this study, we used ultrasonic shot peening (USSP) technology to solve this problem. USSP caused severe plastic deformation of the Al0.3Cu0.5CoCrFeNi HEA surface and dispersed the long-strip Al, Cu-enriched phases into scattered dots, which reduced the galvanic corrosion of the HEA and enhanced passive film formation. The Al, Cu-enriched scattered precipitations also increased the number of Cu2+ ion dissolution sites, leading to the improvement of the alloy’s antibacterial properties. Full article
(This article belongs to the Special Issue Advanced High-Entropy Materials and Coatings)
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12 pages, 3733 KiB  
Article
Influences of Synthetic Parameters on Morphology and Growth of High Entropy Oxide Nanotube Arrays
by Yunzhu Shi, Rui Li and Zhifeng Lei
Coatings 2023, 13(1), 46; https://doi.org/10.3390/coatings13010046 - 27 Dec 2022
Cited by 1 | Viewed by 1897
Abstract
Nanoscale and nanostructured materials have drawn great attention owing to their outstanding and unique properties. Enlightened by the study of “entropy-stabilized oxides”, nanotubes consisting of multi-component mixed metal oxides are developed, which formed on equi-atomic TiZrHfNbTa high-entropy alloy (HEA). However, the growth mechanism [...] Read more.
Nanoscale and nanostructured materials have drawn great attention owing to their outstanding and unique properties. Enlightened by the study of “entropy-stabilized oxides”, nanotubes consisting of multi-component mixed metal oxides are developed, which formed on equi-atomic TiZrHfNbTa high-entropy alloy (HEA). However, the growth mechanism and how the oxidation conditions influence the nanotube growth and morphology remains unknown. In the present study, by controlling the anodization parameters (applied voltages and time) and bath compositions (fluoride concentration and water content), scanning electron microscope and transmission electron microscopy are conducted to reveal the morphological evolution. The present work uncovers how the synthetic parameters influence the tube growth and morphology formed on equi-atomic TiZrHfNbTa HEA, therefore gaining insight into the growth mechanism and the feasibility of controlling the morphology of multi-component oxide nanotubes. Full article
(This article belongs to the Special Issue Advanced High-Entropy Materials and Coatings)
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Review

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14 pages, 4260 KiB  
Review
Microorganisms Involved in the Biodegradation and Microbiological Corrosion of Structural Materials
by M. Saleem Khan, Ke Yang, Zifan Liu, Lujun Zhou, Wenle Liu, Siwei Lin, Xuelin Wang and Chengjia Shang
Coatings 2023, 13(10), 1683; https://doi.org/10.3390/coatings13101683 - 25 Sep 2023
Cited by 4 | Viewed by 1899
Abstract
Microbiologically influenced corrosion (MIC) is the process of material degradation in the presence of microorganisms and their biofilms. This is an environmentally assisted type of corrosion, which is highly complex and challenging to fully understand. Different metallic materials, such as steel alloys, magnesium [...] Read more.
Microbiologically influenced corrosion (MIC) is the process of material degradation in the presence of microorganisms and their biofilms. This is an environmentally assisted type of corrosion, which is highly complex and challenging to fully understand. Different metallic materials, such as steel alloys, magnesium alloys, aluminium alloys, and titanium alloys, have been reported to have adverse effects of MIC on their applications. Though many researchers have reported bacteria as the primary culprit of microbial corrosion, several other microorganisms, including fungi, algae, archaea, and lichen, have been found to cause MIC on metal and non-metal surfaces. However, less attention is given to the MIC caused by fungi, algae, archaea, and lichens. In this review paper, the effects of different microorganisms, including bacteria, fungi, algae, archaea, and lichens, on the corrosion properties of engineering materials have been discussed in detail. This review aims to summarize all of the corrosive microorganisms that directly or indirectly cause the degradation of structural materials. Accusing bacteria of every MIC case without a proper investigation of the corrosion site and an in-depth study of the biofilm and secreted metabolites can create problems in understanding the real cause of the materials’ failure. To identify the real corrosion agent in any environment, it is highly important to study all kinds of microorganisms that exist in that specific environment. Full article
(This article belongs to the Special Issue Advanced High-Entropy Materials and Coatings)
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23 pages, 5843 KiB  
Review
Progress on New Preparation Methods, Microstructures, and Protective Properties of High-Entropy Alloy Coatings
by Kefeng Lu, Jian Zhu, Wenqing Ge and Xidong Hui
Coatings 2022, 12(10), 1472; https://doi.org/10.3390/coatings12101472 - 5 Oct 2022
Cited by 10 | Viewed by 2434
Abstract
Currently, the preparations of high-entropy alloy (HEA) coatings have developed into new methods such as thermal spraying, electrospark deposition technology, and magnetron sputtering. The microstructures and protective properties of HEA coatings prepared by different methods are bound to be different. Moreover, because HEAs [...] Read more.
Currently, the preparations of high-entropy alloy (HEA) coatings have developed into new methods such as thermal spraying, electrospark deposition technology, and magnetron sputtering. The microstructures and protective properties of HEA coatings prepared by different methods are bound to be different. Moreover, because HEAs have a wide range of composition systems, the difference in composition will inevitably lead to a change in process parameters and post-treatment methods, and then affect the microstructures and protective properties. This paper introduces the working mechanism of thermal spraying, electrospark deposition technology, and magnetron sputtering, compares the advantages and disadvantages of each method, and focuses on the influences of the compositions, process parameters, and post-treatment process on the microstructures and properties of the coating. Furthermore, this paper outlines the correlation between preparation methods, process parameters, microstructures, and properties, which will provide a reference for further development of the application of high-entropy alloy coatings. On this basis, the future development direction of HEA coatings is prospected. Full article
(This article belongs to the Special Issue Advanced High-Entropy Materials and Coatings)
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35 pages, 12446 KiB  
Review
High-Entropy Coatings (HEC) for High-Temperature Applications: Materials, Processing, and Properties
by Muhammad Arshad, Mohamed Amer, Qamar Hayat, Vit Janik, Xiang Zhang, Mahmoud Moradi and Mingwen Bai
Coatings 2022, 12(5), 691; https://doi.org/10.3390/coatings12050691 - 18 May 2022
Cited by 28 | Viewed by 7531
Abstract
High-entropy materials (HEM), including alloys, ceramics, and composites, are a novel class of materials that have gained enormous attention over the past two decades. These multi-component novel materials with unique structures always have exceptionally good mechanical properties and phase stability at all temperatures. [...] Read more.
High-entropy materials (HEM), including alloys, ceramics, and composites, are a novel class of materials that have gained enormous attention over the past two decades. These multi-component novel materials with unique structures always have exceptionally good mechanical properties and phase stability at all temperatures. Of particular interest for high-temperature applications, e.g., in the aerospace and nuclear sectors, is the new concept of high-entropy coatings (HEC) on low-cost metallic substrates, which has just emerged during the last few years. This exciting new virgin field awaits exploration by materials scientists and surface engineers who are often equipped with high-performance computational modelling tools, high-throughput coating deposition technologies and advanced materials testing/characterisation methods, all of which have greatly shortened the development cycle of a new coating from years to months/days. This review article reflects on research progress in the development and application of HEC focusing on high-temperature applications in the context of materials/composition type, coating process selection and desired functional properties. The importance of alloying addition is highlighted, resulting in suppressing oxidation as well as improving corrosion and diffusion resistance in a variety of coating types deposited via common deposition processes. This review provides an overview of this hot topic, highlighting the research challenges, identifying gaps, and suggesting future research activity for high temperature applications. Full article
(This article belongs to the Special Issue Advanced High-Entropy Materials and Coatings)
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