摘要: Refractory high-entropy alloys (RHEAs) are being developed to meet mechanical, thermal and chemical requirements that exceed what current super-alloys can withstand. This Review explains how composition design, processing routes and the resulting microstructures now combine to realise that potential. We first link phase selection in BCC-, FCC- and dual-phase RHEAs to atomic-size mismatch, mixing enthalpy and valence-electron concentration, and compare manufacturing paths ranging from arc melting to powder metallurgy, additive manufacturing and vapour deposition, showing how each reshapes grain structure and defect chemistry to improve high-temperature strength, corrosion resistance and irradiation tolerance. Computation-led tools—density-functional theory, CALPHAD and machine learning —shrink the enormous composition space and predict phase stability, transformation paths and oxidation behaviour with increasing accuracy. At the same time, metastable TRIP/TWIP alloys, coherent superlattices and nanoscale heterostructures demonstrate that chemical complexity can overcome the traditional trade-off between strength, ductility and damage tolerance. We propose that combining multi-scale simulation, in-situ characterisation and closed-loop data analysis will speed up the transition of RHEAs from laboratory studies to working engineering components.