A Review on Microstructures, Corrosion Behavior, and Mechanical Properties of Al-Cr-Fe-Co-Ni High-Entropy Alloys

High-entropy alloys (HEAs) represent an emerging class of metallic materials characterized by multi-principal elemental compositions in equimolar or near-equimolar ratios, fundamentally differing from conventional alloys that are typically based on one or two primary elements with minor alloying additions. This innovative alloy design paradigm opens up a new direction for developing advanced structural materials, attracting extensive research interest. Among the various HEA systems, the Al-Cr-Fe-Co-Ni HEAs possess exceptional mechanical properties, including high strength, hardness, and fracture toughness, coupled with superior corrosion, oxidation, and wear resistance, positioning them as promising candidates for high-performance engineering applications. This review systematically summarizes recent progress on the microstructures, corrosion behavior, and mechanical properties of Al-Cr-Fe-Co-Ni HEAs. Particular emphasis is placed on the effects of alloy composition and heat treatment on microstructural evolution and material performance, along with the underlying mechanisms. Furthermore, we critically analyze the underlying mechanisms governing property optimization and identify current knowledge gaps. Based on this assessment, future research directions are proposed to advance both fundamental understanding and practical applications of this HEA system. © ASM International 2025.