EPJ B Topical Review - High critical current densities of body-centered cubic high-entropy alloy superconductors: recent research progress

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Published on 30 April 2025

High-entropy alloys (HEAs) represent a novel paradigm in materials science. HEAs demonstrate a wide array of functionalities, including outstanding mechanical properties, superior corrosion resistance, and durable hard coatings. HEA superconductors have attracted considerable attention due to their distinctive attributes, such as robust superconductivity under extreme conditions and high critical current densities. Several body-centered cubic (bcc) HEAs have shown critical current densities comparable to those of commercial Nb-Ti superconducting alloys. HEAs possess the extraordinary capability to integrate multiple functionalities—a feature seldom observed in conventional alloys. Consequently, bcc HEA superconductors with elevated critical current densities are highly promising for practical applications in extreme environments, such as aerospace and nuclear fusion reactors, owing to the exceptional irradiation resistance characteristic of HEAs.

In a new Topical Review published in EPJ B, Jiro Kitagawa (Fukuoka Institute of Technology, Japan), Yoshikazu Mizuguchi (Tokyo Metropolitan University, Japan) and Terukazu Nishizaki (Kyushu Sangyo University, Japan) have reviewed recent progress in the investigation of critical current densities in bcc HEA superconductors, including Ta_1/6Nb_2/6Hf_1/6Zr_1/6Ti_1/6, (TaNb)_0.7(HfZrTi)_0.5, NbScTiZr, among others. Comparative analyses of these HEAs reveal that both eutectic microstructures, accompanied by lattice strain, and nanoscale precipitates play crucial roles in achieving enhanced critical current densities across broad magnetic field ranges. Additionally, they present a comparative evaluation of the critical current densities between bcc HEAs and Nb-Ti alloys. Notably, some bcc HEAs exhibit critical current density values on par with those of Nb-Ti multifilamentary strands.

They have proposed several future research directions, including the exploration of more refined eutectic microstructures, the deliberate introduction of nanoscale pinning centers, and the examination of the mechanical properties of bcc HEAs to facilitate their development as multifunctional superconducting wires.