Recrystallization behavior and mechanical properties of interstitial equiatomic CoCrFeMnNi High-entropy alloys

Interstitially alloyed high-entropy alloys (HEAs) can benefit profoundly from interstitial solid solution strengthening instead of only the established massive solid solution strengthening provided by their multiple principle elements. This is due to the circumstance that interstitials lead to much higher lattice distortions than substitutional elements which strongly affects their interaction with dislocations. In this project, we aim to understand the interstitial carbon effect on the recrystallization behavior of the equiatomic CoCrFeMnNi HEA and hence to tune the corresponding mechanical properties.

Equiatomic CoCrFeMnNi HEA samples with varying carbon content (0, 0.2 at. %, 0.5 at. % and 0.8 at. %) were cast, hot-rolled and homogenized. They were then cold-rolled and subsequently annealed at different temperatures to reach different recrystallization states. HEA samples with varying carbon content and different recrystallization fractions of the microstructure have been produced and systematically characterized. Microstructures of all samples were examined using the combined EBSD and ECCI techniques. Digital image correlation (DIC) assisted tensile testing is also being conducted. Preliminary results show that the interstitial carbon alloying can lead to significant delay in the recrystallization kinetics of the equiatomic CoCrFeMnNi HEA.