Effect of WC-10Co on microstructure and properties of medium-entropy alloy coatings via electron beam cladding

In this study, non equiatomic FeCrNiCoMoW MEA composite coatings were successfully prepared by electron beam cladding Fe-based amorphous powders. The effects of WC-10Co amounts (0–30 wt%) on the microstructure, mechanical properties, and electrochemical property of the MEA composite coatings were investigated. The added WC-10Co decomposed, and the original amorphous alloy was completely crystallised. The composite coatings primarily comprised the face-centred cubic (FCC) matrix, M23C6 (M = Cr, Mo, Fe, or W) and WC particles. The average hardness of the composite coatings gradually increased with increased WC-10Co amounts from 5.66 ± 1.09 GPa to 8.02 ± 2.54 GPa. The composite coating with 30 wt%WC-10Co showed optimal hardness and wear resistance, which were approximately 4 and 2 times that of the substrate, respectively. The wear mechanism changed from severe adhesive wear for 0 wt% WC-10Co composite coating to abrasive and slight adhesive wear for 10–30 wt% WC-10Co composite coatings. The 10 wt% WC-10Co coating exhibited the best corrosion resistance in 3.5 wt% NaCl solution. The number of corrosion pits decreased with the addition of WC-10Co increased, and corrosion occurred in the Cr-depleted regions. Solid solution, dislocation, WC particles and M23C6 nanoprecipitates were responsible for the improvement in mechanical properties and corrosion resistance of the coatings.