Improving the wear resistance of Ti6Al4V at ambient and elevated temperatures is essential for extending the service life of lightweight components subjected to sliding contact. In this work, Al0.5Ti2NbZrM (M = V, Cr, and W) lightweight refractory high-entropy alloy coatings were first prepared on Ti6Al4V by laser directed energy deposition to investigate the influence of alloying-element selection. Cr alloying promoted the formation of a minor ZrCr2 phase, while W alloying induced multiple BCC phases. Dislocation, precipitation, and grain-refinement strengthening enhanced the hardness and deformation resistance of the Cr- and W-alloyed coatings. The associated microstructural evolution shifted the wear mechanism from combined abrasive–oxidative wear to abrasive wear with fatigue spalling at 25 °C, and toward predominantly oxidative wear at 600 °C. The W-alloyed coating achieved a wear rate of 3.68 × 10-5 mm3/(N·m) at 600 °C, benefiting from the enhanced load-bearing capacity of its multiphase BCC microstructure and the formation of a dense ZrO2 glaze layer. Dispersed subsurface W-rich phases further stabilized this layer and suppressed delamination and adhesive spallation. To further clarify the role of Zr in phase formation and protective oxide development, Zr content was subsequently varied in Al0.5Ti2NbVZrₓ coatings (x = 0, 0.5, 1, and 1.5). Zr addition suppressed needle-like BCC precipitates, yielding a single BCC phase at x = 0.5, whereas higher Zr contents promoted Al2Zr precipitation. Increasing Zr content raised the microhardness from 505.53 to 715.97 HV0.3 through solid-solution strengthening, grain refinement, and secondary-phase strengthening. However, the x = 0.5 coating exhibited the best wear resistance within this series at 25, 400, and 600 °C. Its wear rate reached 3.04 × 10-5 mm3/(N·m) at 600 °C, associated with a uniform and compact oxide layer containing ZrO2, Al2O3, and TiO2. These findings demonstrate that alloying-element selection followed by targeted Zr-content control provides a route to tailoring wear resistance through coordinated microstructural strengthening and protective oxide formation.

Lightweight refractory high-entropy alloy coatings,Compositional design,Microstructural evolution,High-temperature wear,Protective oxide layers