Manufacturing wear-resistant W-based refractory high-entropy alloy coatings through heat treatment-driven microstructural evolution

Refractory high-entropy alloys are promising surface-protection materials for components subjected to elevated temperature, concentrated contact stress and severe sliding wear. However, laser direct energy deposited RHEA coatings exhibit the microstructural heterogeneity and unstable tribological behavior, which restrict their application under the wear-critical conditions. To address this issue, a WMoTaNbV RHEA coating was fabricated on Ti6Al4V alloy by laser direct energy deposition and subsequently tempering treated at 600, 700, and 800 °C. The phase constitution, microstructural evolution, elemental distribution, mechanical properties and tribological behavior were systematically investigated. The results show that the heat treatment (HT) refines and homogenizes the nanostructure while maintaining the BCC-based phase structure, improving the structural stability and resistance to plastic deformation. As the HT temperature is increased from 600 to 800 °C, the average coefficients of friction are decreased from 0.35 to 0.04, while the corresponding wear rates are decreased from 3.55 to 1.68 × 10 −5 mm 3 N −1 m −1 . The improved tribological performance is attributed to the synergistic effects of microstructural refinement, solid-solution strengthening, microstructural stabilization and O-rich protective tribofilm, which reduce the direct contact, plastic deformation and material removal during the sliding wear process. This finding establishes the relationship among the HT-driven nanostructural evolution, tribofilm formation and the transition from severe abrasive/adhesive wear to mild oxidative wear in the WMoTaNbV coating, which is an effective strategy for manufacturing the wear-resistant W-based RHEA coatings.