Laser Cladding of FeCoCrNiNb0.5 High-Entropy Alloy Coating: Microstructure, Nanoindentation Behavior and Wear Behavior

FeCoCrNi coating and FeCoCrNiNb0.5 HEA coatings were deposited onto the surface of a stainless-steel motor main shaft using laser cladding technology. This study investigated the effect of Nb addition on the microstructure, phase composition, crystallographic properties, nanoindentation response, and wear behavior of the FeCoCrNi coating. The results indicated that the FeCoCrNiNb0.5 coating consisted of an FCC phase and a Laves phase. Furthermore, the solid solution of Nb increased the lattice distortion of the FCC phase and enhanced its solute strengthening effect. The addition of Nb significantly improved the nanohardness of the coating. The nanohardness of the FeCoCrNiNb0.5 coating reached 6.47 ± 0.23 GPa, markedly higher than that of the Nb-free FeCoCrNi coating. In addition, the FeCoCrNiNb0.5 coating exhibited higher H/E and H3/E2 ratios, suggesting improved resistance to plastic deformation. Owing to the increased nanohardness, the FeCoCrNiNb0.5 coating demonstrated superior wear resistance, with an average friction coefficient of 0.52 and a wear volume of 5.49 × 105 μm3. The dominant wear mechanisms were identified as abrasive wear, adhesive wear, and oxidative wear.