Comparison of Micro-nano FeCoNiCrAl and FeCoNiCrMn Coatings Prepared from Mechanical Alloyed High-entropy Alloy Powders

High-entropy alloy powders synthesized by mechanical alloying were used as feedstock to prepare FeCoNiCrAl and FeCoNiCrMn coatings by atmospheric plasma spraying. The microstructure and phase composition of the coatings were analyzed by scanning electron microscopy, energy-dispersive spectroscopy, x-ray diffraction, and transmission electron microscopy. The microhardness and wear behavior of the coatings were measured by a microhardness tester and a pin disk-type wear tester, respectively. Polarization curves were plotted to compare the corrosion resistance of the coatings in 3.5 wt.% NaCl solution. It was observed that the FeCoNiCrAl coating was composed of micro-nano face-centered cubic and body-centered cubic solid solutions and a small amount of band-like micro-nano alumina formed during plasma spraying and the FeCoNiCrMn coating was composed of only face-centered cubic solid solution and dispersed nanocrystalline oxide (Mn1.5Cr1.5O4). The average microhardness values of the FeCoNiCrAl and FeCoNiCrMn coatings were determined as 550.1 HV100gf and 440.9 HV100gf, respectively. The FeCoNiCrAl coating had better wear resistance than the FeCoNiCrMn coating. The main wear mechanisms of the FeCoNiCrAl and FeCoNiCrMn coatings were fatigue wear. The FeCoNiCrAl coating had higher corrosion potential, lower corrosion current density, and better corrosion resistance than the FeCoNiCrMn coating.