Effect of Nominal Fe Addition on the Microstructure, Wear Behavior, and Corrosion Resistance of Laser‐Clad CoCrNiFe x (TiNb) 0.2 High‐Entropy Alloy Coatings

CoCrNiFe x (TiNb) 0.2 ( x = 1.0, 0.75, 0.5, 0.25, and 0) high‐entropy alloy coatings were prepared on 30CrMo steel by laser cladding to clarify the effect of nominal Fe addition on microstructure, wear behavior, and corrosion resistance. All coatings were dominated by an FCC solid‐solution matrix with weak reflections assigned to Nb/Ti‐rich C14/C15‐type Laves phases. Changes in nominal Fe addition were accompanied by variations in the FCC diffraction response, substrate dilution, and the morphology of Nb/Ti‐rich network‐like regions. Quantitative image analysis showed a composition‐dependent but nonmonotonic variation in network width, spacing, and connectivity. With decreasing nominal Fe addition, the average microhardness increased from 387.6 ± 9.35 to 454.4 ± 9.48 HV 0.2 , while the wear rate decreased from (1.72 ± 0.13) × 10 −4 to (1.39 ± 0.12) × 10 −4 mm 3 /(N·m). In 3.5 wt.% NaCl solution, the representative fitted charge–transfer resistance increased from 9.21 to 31.21 kΩ·cm 2 and the mean corrosion current density decreased from 0.49 ± 0.08 to 0.18 ± 0.021 μA·cm −2 from Fe 1.0 to Fe 0 . The Fe 0 coating exhibited the most favorable measured electrochemical response. Overall, control of nominal Fe addition produced a multifactor structure–property relationship involving matrix/secondary‐phase morphology, mechanical response, wear damage, and electrochemical behavior.