A review on the effect of various rolling regimes (cryo, cold, warm, hot) and post-annealing on high-entropy alloys: microstructure evolution, deformation mechanisms, and mechanical properties.

Despite their complex composition, high-entropy alloys (HEAs) have a simple structure and have been extensively researched for their ability to achieve unique properties through thermo-mechanical processing (TMP). This review studies the effects of different rolling regimes and post-annealing on single and multiphase HEAs, analyzing how TMP leads to microstructural changes and improved mechanical properties. The rolling changes the shape and utilizes different mechanisms determined by the rolling temperature to strengthen the raw materials, thus affecting the HEAs' properties. The microstructural evolution of HEAs during annealing is affected by various parameters such as annealing time, annealing temperature, and heating rate, which impact the strength–ductility combination of HEAs. According to the literature, cryogenic rolling (cryo-rolling), as opposed to cold rolling, provides greater strengthening. This is due to the faster microstructural evolution kinetics in cryo-rolling. Thus, cryo-rolling enhances the strengthening by activating deformation twinning at earlier stages through the intersection of twins and more shear banding, which is preferred to microbands for HEAs with low stacking fault energy (SFE). Rolling at high temperatures is the most suitable approach for HEAs with low workability. Warm and hot rolling enable microstructure evolution through deformation mechanisms, including grain growth, recovery, recrystallization, and phase transformation based on the process temperature. The ratio of recovery to recrystallization depends on temperature and SFE, with recovery dominating in alloys with high SFE and at lower rolling temperatures, while recrystallization is more prevalent for alloys with low SFE and at higher temperatures, leading to specific ductility–strength synergy. [ABSTRACT FROM AUTHOR]