Microstructure and properties of Nano-WC particle-reinforced lamellar eutectic high-entropy alloy by laser directed energy deposition

This study fabricated AlCoCrFeNi_2.1 eutectic high-entropy alloy (EHEA) composites with varying WC contents (0 wt%, 2.5 wt%, and 5 wt%) via laser-directed energy deposition (DED). The microstructural evolution, mechanical properties, tribological behavior, and corrosion resistance of DED-processed composites were systematically investigated. Results indicate that the pristine EHEA exhibited typical lamellar eutectic structures with epitaxial growth along the thermal gradient direction. WC incorporation refined the as-printed microstructure, transforming the eutectic morphology from lamellar to island-like configurations. Consequently, the DED-EHEA-2.5WC composite demonstrated enhanced yield strength (774 MPa) and ultimate tensile strength (1240 MPa), representing improvements of 14.84 % and 12.22 % over the base EHEA (674 MPa and 1105 MPa), respectively. Wear testing revealed that DED-EHEA-2.5WC exhibited 42.24 % and 38.11 % lower wear rates than DED-EHEA and DED-EHEA-5WC counterparts. Furthermore, optimal WC addition (2.5 wt%) improved corrosion resistance, evidenced by an 81.6 mV nobler corrosion potential and 52.83 % reduction in corrosion current density versus EHEA. XPS analysis confirmed that WC addition stabilized and densified Al₂O₃ passive films, Cr₂O₃ layers, and WO₃ phases through three synergistic mechanisms: reinforcement strengthening, passive film optimization, and oxide phase stabilization. This work proposes a novel strategy for achieving multi-property synergy in additively manufactured eutectic high-entropy alloys.