Decoupling Hardness From Erosion Resistance in High-Entropy Alloys

Abstract One important mechanism of component degradation in particle-rich environments is solid particle erosion. Due to their unique mechanical reactions and compositional complexity, high-entropy alloys (HEAs) have garnered growing interest as erosion-resistant materials. Erosion resistance is often interpreted using hardness-based correlations generated from limited testing settings, despite the fact that several research studies demonstrate enhanced erosion performance of HEAs. This review comprehensively examines erosion studies on HEAs under air-jet solid particle erosion, slurry erosion, cavitation erosion, and erosion–corrosion conditions. Significant discrepancies in test parameters, experimental design, and erosion measures are shown by comparative analysis. These discrepancies hinder meaningful comparisons between studies and obscure the evolution of dominant erosion mechanisms under different impact conditions. The review shows that impact circumstances, microstructure, phase constitution, ductility, and strain-rate-dependent deformation all work together to control erosion behavior in HEAs, which cannot be accurately anticipated by hardness alone. Therefore, creating transferable design concepts for erosion-resistant multi-principal element alloys requires a methodical, mechanism-based approach for evaluating erosion.