Study on wear and corrosion behaviors of nano VC enhanced CoCrNi medium-entropy alloy coatings by laser cladding

Wear and corrosion are common failure modes in underwater components. Traditional alloys struggle to achieve both wear and corrosion resistance, making the development of integrated materials essential for extending service life and improving efficiency. This study fabricated CoCrNi + x (VC) composite coatings via laser cladding to enhance mechanical properties without compromising the excellent corrosion resistance of CoCrNi medium entropy alloy (MEA). The results show that VC precipitated in situ can act as heterogeneous nucleation sites and produce a pinning effect, significantly refining the coating grains. The CoCrNi +15 wt% VC coating exhibits the most excellent mechanical properties under the combined effect of multiple strengthening mechanisms, with a microhardness of 567.83 HV 0.2 . Meanwhile, the dual-phase strengthening structure reduces the wear rate to 0.1026 × 10 −4 mm 3 N −1 m −1 , and its wear mechanism is slight adhesive wear. In a 3.5 wt% NaCl solution, the CoCrNi +10 wt% VC coating exhibits optimal corrosion resistance, with the lowest corrosion current density (8.43 × 10 −8 A cm −2 ) and the highest impedance modulus. The introduction of VC not only suppresses grain boundary corrosion but also promotes the dynamic repair of the passive film through V 5+ , significantly enhancing the stability of the passive film.