Enhanced tribological performance of Cr-Fe-Ni-based chemically complex alloys via dual heterogeneous precipitates

Deploying heterostructures in alloys offers a promising strategy for enhancing tribological properties in more aggressive environments. Herein, dual heterogeneous precipitates were engineered in a Cr₂₉Fe₂₇Ni₃₂Nb₆B₂ chemically complex alloy (CCA) matrix by leveraging Ti-V and Mo-W solute effects, inducing graded grain-size distributions and spatial compositional variations. This tailored microstructure enables synergistic strengthening, yielding compressive strengths of 1.9 and 2.3 GPa, yield strengths of 1.4 and 2.0 GPa, and fracture strains of 20.7 % and 12.1 % in Cr₂₉Fe₂₇Ni₃₂Nb₆Ti₂V₂B₂ and Cr₂₉Fe₂₇Ni₃₂Nb₆Mo₂W₂B₂ CCAs, respectively. Both CCAs exhibit low wear rates of 10−6-10−5 mm3/Nm at room-temperature and 800°C, which are attributed to the multiscale dual-heterogeneous microstructure that enhances mechanical strength and the formation of protective tribo-oxides under high-temperature sliding. Notably, heterogeneous precipitate-mediated subsurface strengthening stabilizes the glaze layer, suppressing adhesive spallation and plastic delamination upon high-temperature wear. © 2025 Elsevier Ltd.