Plasma-Sprayed NiCrCuMoB High Entropy Alloy Coating with Low Oxide Content Enabled by Boron Alloyed Powder

Abstract In this study, a high-entropy alloy (HEA) powder containing boron (NiCrCuMoB) was developed for atmospheric plasma spraying to produce coatings with minimal oxide formation in the molten droplets. The in-situ deoxidizing effect of boron during flight was investigated by analyzing collected HEA particles. The oxidation behavior of individual splats deposited on polished stainless-steel substrates was also examined. The resulting coating microstructure and mechanical properties were characterized. The results demonstrate that the addition of boron effectively suppresses in-flight oxidation of the molten particles, leading to the production of HEA particles with low oxide content. Consequently, bulk-like HEA coatings exhibiting strong metallurgical bonding and a reduced oxide content were achieved due to the deoxidizing action of boron.