Evaluating microstructural changes and hardness in equal atomic Ni-Al-Co-Fe-Mn-Ti-Cr high-entropy alloy subjected to heat treatment in oxidative and non-oxidative environments

Microstructural changes and hardness behaviour of equal atomic Ni-Al-Co-Fe-Mn-Ti-Cr High-Entropy Alloy (HEA) subjected to heat treatment in oxidative and non-oxidative environments were investigated. The samples were annealed for four hours at a temperature of 700 °C. The microstructure revealed the formation of a well-refined granular and needle-like eutectic phase with an average size. An oxidized layer was observed on the surface of the sample heat-treated in an oxidized environment. The heat-treated samples exhibited improved ductility with a drop in hardness value from 136.3 HV for the non-heat-treated to 98.1 and 92.8 HV for the heat-treated in an oxidized and non-oxidized environment, respectively. The heat treatment results can be considered a promising approach for producing high-performance HEAs, particularly for advanced engineering applications.