High Entropy Alloys: A Comprehensive Review for Engineering Applications

Materials science is currently navigating a fundamental transition away from traditional, single-base element systems toward compositions featuring multiple principal elements mixed in near-equiatomic ratios, known as High Entropy Alloys (HEAs). In a departure from conventional metallurgical principles, the high configurational entropy inherent to these systems stabilizes simple solid solution phases. This paper provides a critical examination of recent progress made between 2020 and 2025, bridging fundamental alloy theories with modern practices in computational design and metastability engineering. The review systematically breaks down microstructural evolution, advanced manufacturing techniques, empirical phase formation models, and the four governing kinetic and thermodynamic effects. By detailing modern deformation behaviors—namely Transformation-Induced Plasticity (TRIP) and Twinning-Induced Plasticity (TWIP)—the mechanical responses of multiphase, BCC, and FCC microstructures are compared. The manuscript concludes by outlining the significant potential for HEA integration within the nuclear, cryogenic, and aerospace sectors, alongside an assessment of prevailing research obstacles regarding industrial scaling and high-temperature oxidation.