Alloying effects on the microstructure and properties of CoCrFeMnNiX0.1 high-entropy alloys via rolling and thermal treatment

This study fabricated four kinds of CoCrMnFeNiX0.1 (X = Al, Cu, Mo, Ti) high-entropy alloys through rolling with subsequent thermal treatment, to investigate the alloying effects on the microstructural evolution, mechanical properties, and electrochemical corrosion performance. High-density parallel twinning bands were observed in the as-rolled CoCrMnFeNiX0.1 alloys, excluding the Cu0.1 variant, signifying that plastic deformation was dominated by twinning. However, detwinning and thickening of twin layers was observed after annealing. This effect was more pronounced in the rolling direction-normal direction (RD-ND) plane due to the stress state induced by rolling. The introduction of Cu altered the deformation mechanism to a combination of twinning and slipping, resulting in fewer twinning bands. Notably, annealing induced the formation of abundant bamboo-shaped twinning bands (width: 10 nm) in the Cu0.1 alloy, which were correlated with nano precipitated particles. Additionally, the incorporation of Mo or Al elements activated more twinning directions, thereby enhancing plasticity. For the Ti0.1 alloy, the primary factors influencing the altered tensile and electrochemical performances were the formation and growth of few precipitated particles during annealing. Consequently, the strengthening effect can be ranked in the order of Mo > Ti > Al > Cu. Therefore, the addition of Al and Ti is recommended for improving the anticorrosive property and thermal stability of recrystallized grains.