The objective of the study is to understand the evolution of structure during annealing of a cryogenically rolled medium entropy alloy and compare the annealing behavior with a high entropy alloy. The understanding of annealing kinetics is important to optimize the mechanical properties. Cryogenically rolled medium entropy alloy (CoCrNi) was annealed in the temperature range of 600–850 °C. Recrystallization occurred at a temperature of 600 °C, which is about 200 °C lower than the temperature required to induce recrystallization in the CoCrFeMnNi high entropy alloy at identical cryogenically rolling reduction of ~30%. High fraction of annealing twins was observed with fraction in the range of ~53–59%. The geometrically necessary dislocation density for the annealed alloy was ~1 × 1014 m−2. The study underscores that the annealing temperature depends on the number and nature of constituent elements in the alloy. A high annealing temperature is conducive to the formation of annealing twins when the unstable deformed microstructure transforms into a new equilibrium and recrystallized structure.
R. Devesh Kumar Misra (Tue,) studied this question.