Microstructural-mechanical property correlation via nanoindentation mapping in CoCrFeNiMo0.5 high-entropy alloy powder and cold spray coating

Single-phase FCC structure-dominated high entropy alloys (HEAs) such as CoCrFeNi exhibit excellent ductility and thermal stability but challenge its adaptability for industrial applications due to strength-ductility trade-offs and substandard wear performance. The addition of Mo to CoCrFeNi promotes the formation of fine sigma-phase precipitates, leading to significant improvements in mechanical performance. This study investigates the relationship between microstructure and mechanical properties of CoCrFeNiMo_0.5 HEA, utilizing the nanoindentation technique to assess the effects of sigma-phase formation on nanoscale mechanical behaviour. Accelerated property mapping, coupled with scanning electron microscopy (SEM) and electron backscatter diffraction (EBSD), was applied to both gas-atomized powders and cold-sprayed coatings to analyze phase composition, microstructure, and the impact of cold spray processing on mechanical properties. The pile-up morphologies and differences in load-displacement curves provide vital information on the mechanical behaviour of CoCrFeNiMo_0.5 HEA. Additionally, the study provides valuable insights into how cold spray-induced deformation affects the intrinsic properties of HEAs.