In Situ Hierarchical Nanostructures toward Unprecedented Wear Resistance in Eutectic High-Entropy Alloys

Modulating the multiphase microstructures is a key approach to enhancing the wear properties of metallic materials. Expanding upon the microcomposite nature of eutectic high-entropy alloys (EHEAs), we harness carbon alloying to synthesize nanoscale eutectic carbides in situ, while the resulting elemental repartitioning simultaneously tailors ultrafine BCC nanoprecipitates within the B2 matrix. This brand-new design of hierarchical nanostructures achieves a record-low dry wear rate of 1.15 × 10-5 mm3 N-1 m-1 among EHEAs. Highly dispersed M7C3 nanocarbides with strong interfacial bonding not only suppress surface nanocrystallization but also activate deformation twinning in the FCC phase for high deformation resistance. Furthermore, spherical BCC nanoprecipitates with near-zero lattice misfit enhance the elastic recovery of the BCC matrix and prevent crack initiation at the B2/BCC interfaces owing to negligible strain accumulation. These findings provide a controllable and scalable pathway for nanostructure tailoring, establishing a blueprint for synergistic dual-phase engineering in next-generation wear-resistant EHEAs.