Chemical short-range order as a design parameter in medium- and high-entropy alloys: From atomic interactions to mechanical and environmental performance

Medium- and high-entropy alloys are often treated as random solid solutions, yet growing evidence shows that preferential atomic correlations can produce chemical short-range order (SRO) and substantially alter their properties. This review examines the thermodynamic and kinetic origins of SRO, the experimental and computational methods used to resolve it, and its effects on defect energetics, deformation and environmental stability. Across compositionally distinct alloy systems, SRO modifies local bonding, lattice strain and magnetic interactions, thereby reshaping stacking-fault-energy landscapes, dislocation motion, twinning and phase transformation. These effects can promote strength–ductility synergy, but they are not universal and depend strongly on composition, processing history, temperature and magnetic state. Emerging studies further suggest that SRO influences diffusion, passivation, oxidation and hydrogen transport, although direct mechanistic evidence remains limited. We identify multimodal characterization, standardized SRO descriptors and integrated atomistic–data-driven modelling as essential for transforming SRO from an observed local feature into a controllable design parameter for advanced alloys.