B induces Cr grain boundary enrichment and the enhanced anti-tribocorrosion property of HEA composite coatings

The high-entropy composite coatings with TaC and B-reinforced FeCoCrNiCu were successfully prepared by laser cladding to investigate their wear, corrosion, and tribo-corrosion behaviors. Different from the fine grain strengthening caused by the direct addition of TaC, the doping of B induced the obvious enrichment of Cr at the grain boundary and Cr₂B is precipitated. Thus, the microhardness of the B-doped coating is strengthened to 343.98 HV_0.5, which is 2.14 times that of the substrate. The high proportion of less-angle grain boundaries significantly improves the durability of coatings in corrosive environments by reducing grain boundary energy, reducing active sites and optimizing grain boundary grid stability. And, the B-enhanced coating exhibits chemical inertness, making them less likely to react with corrosive substances in the environment. This property helps inhibit corrosion and wear. The corrosion resistance of the coating is greatly improved. In B reinforced coating, the I_corr value (0.17 × 10⁻⁶ A/cm²) is 0.08 times that of the substrate. The advanced corrosion-wear resistance (1.33 × 10⁻⁶ mm³/Nm) is also obtained by B-enhanced coating, which decreased by 96.8 % compared to substrate. From the three tests including wear, corrosion, and tribocorrosion, the corrosion-wear behavior of B doped coating is dominated by anti-corrosion.