Laser cladding of FeCoCrNiTi high-entropy alloy coatings to modulate the microstructure and enhance the tribo-corrosion behavior on 304 stainless steel

Abstract

Coatings of the FeCoCrNiTi high-entropy alloy (HEA) were fabricated through laser cladding on 304 stainless steel (304SS) using various laser energy densities, intending to adjust the microstructure and improve the tribo-corrosion characteristics. The results showed that the HEA coatings with good metallurgical bonding can be achieved under appropriate laser parameters. The coating thicknesses exhibited a decreasing trend with reduced laser energy density, and the grain size of the coatings was also reduced from 57.52 μm to 27.23 μm, accompanying by the increase of microhardness from 178.1 HV for the substrate to 380.6 HV in the HEA coating. The FeCoCrNiTi HEA coating exhibited FCC and BCC dual-phase structure, which was in agreement with the thermodynamically calculated results. The average Schmid factor decreased from 0.440 to 0.423. At a laser energy density of 40 J/mm², the coating exhibited the best comprehensive performance, with the lowest coefficient of friction (0.438), the highest corrosion potential (−350.9 mV), and the lowest corrosion current density (3.51 × 10⁻⁶ A/cm²). After 10 h of cavitation erosion (CE) testing, the coating obtained at a laser energy density of 40 J/mm² displayed the lowest cumulative mass loss, which can be attributed to the strong resistance of its grain structure to plastic deformation, the high stability and good self-healing ability of its passive film during cavitation erosion.