Effects of Laser Energy Density on Microstructure and Properties of FeCoCrNiMo High-Entropy Alloy Coatings on 45 Steel Substrate

In this paper, FeCoNiCrMo high-entropy alloys (HEAs) coatings was prepared on 45 steel substrate. The effects of laser energy density on the phase structure, microstructure, tribology and electrochemical properties of the coatings were studied. The results show that the structure of the coatings phase is mainly FCC and σ, and the structure is typical dendrite. With the increase in laser energy density, crystal structure and orientation becomes more complex. At the energy density of 134.4 J∙mm⁻², the coatings reaches its maximum hardness of 522HV, 2.5 times that of the 45 steel, and the minimum wear rate is 3.56 × 10⁻⁶ g·N⁻¹·m⁻¹. The polarization curve and EIS results show that at the energy density of 132.61 J∙mm⁻², which the minimum self-corrosion current density of the coatings is 4.563 × 10⁻⁶A∙cm⁻². The energy density significantly improves the comprehensive mechanical properties of HEA coatings.