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Metals
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Advances in High-Entropy Alloys’ Microstructure, Properties and Preparation
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Advances in High-Entropy Alloys’ Microstructure, Properties and Preparation

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

Deadline for manuscript submissions: 20 August 2025 | Viewed by 3378

Special Issue Editor

Dr. Chao Yang

E-Mail Website
Guest Editor
School of Materials Science and Engineering, Shanghai Jiao Tong University, Shanghai 200240, China
Interests: high entropy alloys; high-throughput alloy design; additive manufacturing; powder metallurgy
Special Issues, Collections and Topics in MDPI journals

Special Issue Information

Dear Colleagues,

The advent of high- and medium-entropy alloys (HEAs and MEAs) has broken through traditional alloy design methodologies, attracting increasing research attention due to their advanced performance and outstanding properties. Recent progress in compositional and structural design concepts, as well as preparation techniques, have further enhanced the performance of HEAs and MEAs, a topic within the scope of this Special Issue. Owing to excellent strength–ductility tradeoff, fracture toughness at ambient and cryogenic temperatures, high-temperature capability, tribological performance, irradiation behavior, corrosion/oxidation resistance, etc., HEAs and MEAs are considered promising candidates for future applications in a wide range of industries, including in the aerospace, nuclear, marine, biomedical, energy, and mining fields.

In this Special Issue, we welcome review articles and research papers that focus on microstructure, property, and preparation advances in high-entropy alloys and shed light on future research directions. The topics will include but are not limited to the following: (1) various types of HEAs and MEAs, including 3D transitional, refractory, lightweight, single-phase, precipitation-strengthened, eutectic/eutectoid, gradient, and bimodal-grained models; (2) various strengthening and plasticity mechanisms, including twining, phase transformation, dispersed particles, nanostructures, dislocation structures, microbands, and cell structures; (3) various advanced design methods, including high-throughput thermodynamics/kinetics calculation and screening, machine learning, molecular dynamics, and density functional theory; (4) various advanced preparation techniques, including arc-melting, powder metallurgy, additive manufacturing for bulk HEAs and MEAs, and jet/plasma spraying for HEA and MEA coatings; and (5) various advanced characterization tools, including 3D atomic probe tomography and in situ transmission electron microscope.

Dr. Chao Yang
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. 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

  • high-entropy alloys
  • medium-entropy alloys
  • refractory high-entropy alloys
  • mechanical performance
  • computational-aided design
  • powder metallurgy
  • additive manufacturing
  • transformation-induced plasticity
  • heterostructure

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Published Papers (5 papers)

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Research

14 pages, 1940 KiB  
Article
Nanoporous CuAuPtPd Quasi-High-Entropy Alloy Prism Arrays for Sustainable Electrochemical Nitrogen Reduction
by Shuping Hou, Ziying Meng, Weimin Zhao and Zhifeng Wang
Metals 2025, 15(5), 568; https://doi.org/10.3390/met15050568 (registering DOI) - 21 May 2025
Abstract
Electrochemical nitrogen reduction reaction (NRR) has emerged as a promising approach for sustainable ammonia synthesis under ambient conditions, offering a low-energy alternative to the traditional Haber–Bosch process. However, the development of efficient and sustainable electrocatalysts for NRR remains a significant challenge. Noble metals, [...] Read more.
Electrochemical nitrogen reduction reaction (NRR) has emerged as a promising approach for sustainable ammonia synthesis under ambient conditions, offering a low-energy alternative to the traditional Haber–Bosch process. However, the development of efficient and sustainable electrocatalysts for NRR remains a significant challenge. Noble metals, known for their exceptional chemical stability under electrocatalytic conditions, have garnered considerable attention in this field. In this study, we report the successful synthesis of nanoporous CuAuPtPd quasi-high-entropy alloy (quasi-HEA) prism arrays through “melt quenching” and “dealloying” techniques. The as-obtained alloy demonstrates remarkable performance as an NRR electrocatalyst, achieving an impressive ammonia synthesis rate of 17.5 μg h−1 mg−1 at a potential of −0.2 V vs. RHE, surpassing many previously reported NRR catalysts. This work not only highlights the potential of quasi-HEAs as advanced NRR electrocatalysts but also provides valuable insights into the design of nanoporous multicomponent materials for sustainable energy and catalytic applications. Full article
(This article belongs to the Special Issue Advances in High-Entropy Alloys’ Microstructure, Properties and Preparation)
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18 pages, 6883 KiB  
Article
New FeMoTaTiZr High-Entropy Alloy for Medical Applications
by Miguel López-Ríos, Julia Mirza-Rosca, Ileana Mariana Mates, Victor Geanta and Ionelia Voiculescu
Metals 2025, 15(3), 259; https://doi.org/10.3390/met15030259 - 27 Feb 2025
Viewed by 512
Abstract
High-entropy alloys are novel metallic materials distinguished by very special mechanical and chemical properties that are superior to classical alloys, attracting high global interest for the study and development thereof for different applications. This work presents the creation and characterisation of an FeMoTaTiZr [...] Read more.
High-entropy alloys are novel metallic materials distinguished by very special mechanical and chemical properties that are superior to classical alloys, attracting high global interest for the study and development thereof for different applications. This work presents the creation and characterisation of an FeMoTaTiZr high-entropy alloy composed of chemical constituents with relatively low biotoxicity for human use, suitable for medical tools such as surgical scissors, blades, or other cutting tools. The alloy microstructure is dendritic in an as-cast state. The chemical composition of the FeMoTaTiZr alloy micro-zone revealed that the dendrites especially contain Mo and Ta, while the inter-dendritic matrix contains a mixture of Ti, Fe, and Zr. The structural characterisation of the alloy, carried out via X-ray diffraction, shows that the main phases formed in the FeMoTaTiZr matrix are fcc (Ti7Zr3)0.2 and hcp Ti2Fe after annealing at 900 °C for 2 h, followed by water quenching. After a second heat treatment performed at 900 °C for 15 h in an argon atmosphere followed by argon flow quenching, the homogeneity of the alloy was improved, and a new compound like Fe3.2Mo2.1, Mo0.93Zr0.07, and Zr(MoO4)2 appeared. The microhardness increased over 6% after this heat treatment, from 694 to 800 HV0.5, but after the second annealing and quenching, the hardness decreased to 730 HV0.5. Additionally, a Lactate Dehydrogenase (LDH) cytotoxicity assay was performed. Mesenchymal stem cells proliferated on the new FeMoTaTiZr alloy to a confluence of 80–90% within 10 days of analysis in wells where the cells were cultured on and in the presence of the alloy. When using normal human fibroblasts (NHF), both in wells with cells cultured on metal alloys and in those without alloys, an increase in LDH activity was observed. Therefore, it can be considered that certain cytolysis phenomena (cytotoxicity) occurred because of the more intense proliferation of this cell line due to the overcrowding of the culture surface with cells. Full article
(This article belongs to the Special Issue Advances in High-Entropy Alloys’ Microstructure, Properties and Preparation)
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14 pages, 5744 KiB  
Article
Effect of Multi-Phase Composite Structure on the Mechanical Properties of AlxFe1.5CoNiC0.12 High Entropy Alloys
by Yiteng Jiang, Aoxiang Li, Kaiwen Kang, Jinshan Zhang, Di Huang, Chunning Che, Saike Liu, Mingkun Xu, Yaqing Li, Borui Zhang and Gong Li
Metals 2025, 15(2), 203; https://doi.org/10.3390/met15020203 - 14 Feb 2025
Viewed by 592
Abstract
Single-phase high entropy alloys (HEAs) exhibit limited mechanical properties while dual-phase and multi-phase HEAs offer better strength, toughness, and stability. In this paper, the as-cast AlxFe1.5CoNiC0.12 HEAs with triple-phase dendritic composite structure is studied, and the influence of [...] Read more.
Single-phase high entropy alloys (HEAs) exhibit limited mechanical properties while dual-phase and multi-phase HEAs offer better strength, toughness, and stability. In this paper, the as-cast AlxFe1.5CoNiC0.12 HEAs with triple-phase dendritic composite structure is studied, and the influence of the composite structure on the mechanical properties is discussed. The interdendrite (ID) of this structure is composed of a uniformly distributed high-density ordered face-centered cubic structure (L12) precipitate phase and face-centered cubic (FCC) matrix, while the dendrite (DR) consists of an ordered body-centered cubic (B2) single-phase. The high density L12 precipitate phase leads to a higher hardness in the FCC+L12 dual-phase region compared to the B2 single-phase region. The decrease in Al content can greatly improve mechanical performance. The improvement was attributed to the higher volume fraction of the ID and the smaller particle size of the precipitates. The L12 phase nano-precipitates exhibit minimal lattice mismatch with the FCC matrix, thereby significantly enhancing the stability of the alloy at the nanoscale. This stability is reflected in the fracture morphology. Modulating the triple-phase dendritic composite structure effectively improves the mechanical properties of the alloy. Full article
(This article belongs to the Special Issue Advances in High-Entropy Alloys’ Microstructure, Properties and Preparation)
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16 pages, 7149 KiB  
Article
Corrosion Behavior and Microhardness of a New B4C Ceramic Doped with 3% Volume High-Entropy Alloy in an Aggressive Environment
by Alberto Daniel Rico-Cano, Julia Claudia Mirza-Rosca, Burak Cagri Ocak and Gultekin Goller
Metals 2025, 15(1), 79; https://doi.org/10.3390/met15010079 - 17 Jan 2025
Cited by 1 | Viewed by 934
Abstract
The aim of this paper is to study both the mechanical and chemical properties of a new material composed of B4C doped with 3% volume of CoCrFeNiMo HEA by the spark plasma sintering technique. Scanning electron microscopy and microhardness were used [...] Read more.
The aim of this paper is to study both the mechanical and chemical properties of a new material composed of B4C doped with 3% volume of CoCrFeNiMo HEA by the spark plasma sintering technique. Scanning electron microscopy and microhardness were used to characterize the composite microstructure and hardness. Corrosion behavior was studied by corrosion potential, corrosion rate and electrochemical impedance spectroscopy, where the equivalent circuit was obtained, characterized by the presence of the Warburg element. The addition of HEA resulted in a more compact microstructure, filling pores and inhibiting ceramic grain growth. A microhardness statistical analysis revealed that the sample followed a normal distribution, which suggests that the sample has a homogeneous structure. The doped material exhibits excellent corrosion resistance in artificial seawater, where its chemical interaction occurs in two steps, with an important diffusional component. This study highlights the potential for use in environments where both corrosion resistance and mechanical strength are critical factors. Full article
(This article belongs to the Special Issue Advances in High-Entropy Alloys’ Microstructure, Properties and Preparation)
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12 pages, 7334 KiB  
Article
Microstructure and Wear Behavior of AlxCoCuNiTi (x = 0, 0.4, and 1) High-Entropy Alloy Coatings
by Mingxing Ma, Zhixin Wang, Chengjun Zhu, Ying Dong, Liang Zhao, Lixin Liu, Dachuan Zhu and Deliang Zhang
Metals 2024, 14(11), 1280; https://doi.org/10.3390/met14111280 - 11 Nov 2024
Cited by 3 | Viewed by 853
Abstract
AlxCoCuNiTi (x = 0, 0.4, and 1) high-entropy alloy coatings on 45 steel substrates were prepared by laser cladding, and their phase structure, microstructure, element partition, and wear behavior were investigated. The results show that the AlxCoCuNiTi (x = [...] Read more.
AlxCoCuNiTi (x = 0, 0.4, and 1) high-entropy alloy coatings on 45 steel substrates were prepared by laser cladding, and their phase structure, microstructure, element partition, and wear behavior were investigated. The results show that the AlxCoCuNiTi (x = 0, 0.4, and 1) coatings have a dual-phase structure of FCC and BCC. With the increase of x from 0 to 1, the content of the FCC phase decreases from 66.9 wt.% to 14.3 wt.%, while the content of the BCC phase increases from 33.1 wt.% to 85.7 wt.%. When x = 0.4, the lattice constants of the two phases are the largest, and their densities are the smallest. The microstructure of the AlxCoCuNiTi (x = 0, 0.4, and 1) coatings is composed of BCC-phase dendrites and FCC-phase interdendrite regions. Ti is mainly enriched in the primary phase or BCC dendrites, Cu is enriched in the interdendrite regions, and Al is enriched in the dendrites. The friction coefficients of AlxCoCuNiTi (x = 0, 0.4, and 1) coatings during wear tests are 0.691, 0.691, and 0.627, respectively. The lowering of the wear friction coefficient when increasing the Al content is mainly related to the change in phase structure, microstructure, and wear mechanism. Full article
(This article belongs to the Special Issue Advances in High-Entropy Alloys’ Microstructure, Properties and Preparation)
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