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 degrees 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.