Niobium and Molybdenum as Alloying Constituents in Al_0.3CoCrFeNi to Develop Eutectic High-Entropy Alloys for HVOF Spraying

The addition of refractory metals represents a promising development approach for future high-entropy alloys (HEAs). Niobium and molybdenum are particularly suitable for increasing hardness as well as wear and corrosion resistance. In the context of surface protection applications, eutectic alloys with their homogeneous property profile are of particular interest. In the present work, two eutectic HEAs (EHEAs) were developed for the starting Al_0.3CoCrFeNi using electric arc furnace. Following mechanical and microstructural characterization, the two alloys Al_0.3CoCrFeNiMo_0.75 and Al_0.3CoCrFeNiNb_0.5 were identified. For thermal spray processing, powders were prepared by inert gas atomization. The coatings produced by high velocity oxy-fuel (HVOF) spraying were characterized and evaluated comparatively to the castings, allowing process-structure-property relationships to be derived. Based on the results, statements on possible application potential can be made.