Abstract
The microstructure, microhardness and corrosion resistance (in a 1 M NaCl solution) of as-cast AlxCoCrFeNiMo0.5 (x = 0, 0.25, 0.5) high-entropy alloys (HEAs) were studied. The as-cast samples exhibited a dendritic microstructure in which a (CrFeMo)-type molybdenum-rich σ-phase precipitated in the interdendritic space. It was determined that Al alloying increases the microhardness from 285 HV0.3 for CoCrFeNiMo0.5 HEA to 628 HV0.3 for Al0.5CoCrFeNiMo0.5 HEA. At the same time, aluminum has a negative effect on the corrosion resistance of the studied alloys, where an increase in Al concentration, increases the corrosion current by two orders of magnitude.