Silicon‐Induced Microstructural Refinement and Its Influence on Tribological and Corrosion Behavior of CoCrFeMnNi High‐Entropy Alloys

This study examines the impact of silicon addition on the microstructure and properties of CoCrFeMnNiSi _x ( x = 0–0.9) high‐entropy alloys fabricated by vacuum arc melting. XRD confirms a single FCC solid solution for all x , with the lattice parameter increasing from 3.545 Å ( x = 0) to 3.575 Å ( x = 0.9) and diffraction peaks shifting to lower 2 θ . SEM/EDS shows Si‐accentuated dendritic/interdendritic partitioning and refinement. Microhardness increases from 150 HV ( x = 0) to 400 HV ( x = 0.9), consistent with solid‐solution and grain‐boundary strengthening. Dry sliding tribology shows the steady‐state friction coefficient decreases from 0.57 to 0.39, while the peak friction drops from 0.92 to 0.75. In 3.5 wt.% NaCl, corrosion performance improves markedly. Ecorr shifts from −360.6 to −247.3 mV and Icorr decreases from 1.16 × 10 ⁻⁵ to 2.45 × 10 ⁻⁷ A cm ⁻² for x = 0 to x = 0.9. Silicon thus enables concurrent FCC lattice expansion, microstructural refinement, higher hardness, better wear response, and superior corrosion resistance.