Understanding the physical metallurgy of the CoCrFeMnNi high-entropy alloy: an atomistic simulation study

High-entropy alloys (HEAs) have garnered academic interest due to their promising properties as structural materials. This study aims to clarify the physical metallurgical mechanisms related to the CoCrFeMnNi HEA through atomistic simulations including Monte Carlo and molecular dynamics methods. We investigate the effects of individual elements on solid solution hardening and examine phenomena such as sluggish diffusion and micro-twinning at cryogenic temperatures. Our findings indicate the presence of a significant number of stable vacant lattice sites with high migration energy barriers, which are believed to contribute to sluggish diffusion. Additionally, we predict that the hexagonal close-packed (hcp) structure is more stable than the face-centered cubic (fcc) structure at 0 K, which serves as a fundamental reason for the observed micro-twinning at cryogenic temperatures. The alloying effect on the critical resolved shear stress (CRSS) is accurately predicted using atomistic simulations and is validated experimentally. This study demonstrates the potential of combining atomistic approaches with thermodynamic calculations for the computational design of advanced HEAs.