Microstructure and tribological performance of FeCrNiMox medium-entropy alloy (MEA) coatings by high-speed laser cladding: Effect of molybdenum content

Abstract

In this study, FeCrNiMo_x coatings (x=0, 0.25, 0.5, 0.75, 1.0, in molar ratio) were fabricated on 45# steel using high-speed laser cladding technology. The objective is to investigate the effect of Mo content on microstructure and tribological performance of the FeCrNiMo_x coatings. The results reveal that the σ phase precipitates at the grain boundaries of the FCC matrix phase when the Mo molar ratio exceeds 0.75. Moreover, coatings with high Mo content demonstrate improved hardness and tribological performance due to solid solution strengthening, precipitation hardening, and grain refinement. Optimal coating performance occurred at Mo molar ratio of 0.75, as excessive σ phase precipitation at higher Mo levels results in crack formation, which reduces the coating density and properties.