Strong, Ductile and Corrosion-Resistant High-Entropy Alloys

A topical collection in Coatings (ISSN 2079-6412). This collection belongs to the section "Corrosion, Wear and Erosion".

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Editors

Tianjin Key Laboratory of Materials Laminating Fabrication and Interface Control Technology, School of Materials Science and Engineering, Hebei University of Technology, Tianjin 300130, China
Interests: high-entropy alloys; mechanical behavior; deformation mechanism
School of Materials Science and Engineering, Hebei University of Technology, Tianjin 300401, China
Interests: Cs-STEM; in situ TEM; nanoindentation; alumina; titanium; twinning
Special Issues, Collections and Topics in MDPI journals

Topical Collection Information

Dear Colleagues,

High-entropy alloys (HEAs), consisting of four or more elements in an equiatomic or near-equiatomic compositions, and their potential applications in harsh environments have attracted a great deal of attention. Superior properties have been reported in HEAs in comparison with conventional alloys, including excellent strength–ductility–toughness combinations, as well as resistance to radiation, corrosion and oxidation. However, the strength and corrosion resistance are generally mutually exclusive. From a corrosion standpoint, a single-phase homogeneous solid solution with both structural and chemical uniformities is desirable for better corrosion resistance instead of multiple phases. From a mechanical standpoint, single-phase alloys exhibit relatively low mechanical strength for engineering applications. Secondary strengthening phases are required to promote the strength–ductility synergy. Unfortunately, secondary phases in precipitation-strengthened alloys often generate significant micro-galvanic corrosion, and especially the heterogeneous nucleation of these strengthening phases at grain boundaries causes severe localized corrosion. Therefore, how to design strong, ductile and corrosion-resistant HEAs via compositional and microstructural control within their near-infinite compositional and phase spaces is critical for realizing their applications in harsh environments.

This Special Issue plans to give an overview of the most recent advances in the mechanical properties and corrosion resistance of HEAs. This Special Issue aims to provide selected contributions on advances in the fabrication, characterization, and exploration in the strengthening, toughening, and corrosion-resistance mechanisms of HEAs. Potential topics include, but are not limited to the fabrication of bulk HEAs or high-entropy coatings; mechanical properties; strengthening mechanisms; corrosion resistance; passive films; and future perspectives for HEAs for applications in harsh environments.

Dr. Kaisheng Ming
Dr. Bin Miao
Collection Editors

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Keywords

  • high-entropy alloys
  • mechanical properties
  • corrosion resistance
  • passive films
  • microstructures

Published Papers (1 paper)

2022

15 pages, 11967 KiB  
Article
Tailoring Mechanical and Electrochemical Properties of the Cr15Fe20Co35Ni20Mo10 High-Entropy Alloy via the Competition between Recrystallization and Precipitation Processes
by Bo Li, Kaisheng Ming, Lichen Bai, Jing Wang and Shijian Zheng
Coatings 2022, 12(7), 1032; https://doi.org/10.3390/coatings12071032 - 21 Jul 2022
Cited by 1 | Viewed by 1346
Abstract
A strategy to improve the mechanical and electrochemical properties of Cr15Fe20Co35Ni20Mo10 (Mo10) high-entropy alloys (HEA) by regulating the thermal-mechanical process was investigated. Due to the mutual competition between recrystallization and μ-phase precipitation [...] Read more.
A strategy to improve the mechanical and electrochemical properties of Cr15Fe20Co35Ni20Mo10 (Mo10) high-entropy alloys (HEA) by regulating the thermal-mechanical process was investigated. Due to the mutual competition between recrystallization and μ-phase precipitation behavior, the microstructure after annealing consists of recrystallized fine face-centered cubic grains with numerous annealing twins, non-recrystallized deformed grains with high-density dislocations as well as high-density nanoscale μ-phase precipitates. The combination of grain boundary strengthening, precipitation strengthening, and hetero-deformation induced strengthening endowed an ultrahigh yield strength of 1189 MPa and a uniform elongation of 17.5%. The increased yield strength activated the formation of stacking faults and deformation twinning as the additional deformation modes, which enabled the Mo10 HEA to exhibit a high strain-hardening rate and thus maintained superior ductility and enhanced tensile strength. Most importantly, when high-density dislocations accumulate at the phase boundaries, the nanoscale μ-phase can plastically deform by dislocation slips and the formation of stacking faults, which can relieve the high stress concentrations and thus prevent the cracking. The electrochemical properties of the annealed Mo10 HEA are decreased (compared to the homogenized ones), but can be optimized by adjusting the content and size and fraction of the μ-phase. This work sheds light on developing high-performance HEAs. Full article
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