Mechanism of dislocation evolution during plastic deformation of nitrogen-doped CoCrFeMnNi high-entropy alloy

Abstract

Abstract In this study, the evolution of statistically stored dislocation (SSD) and geometrically necessary dislocation (GND) during tensile tests was investigated in CoCrFeMnNi high-entropy alloys (HEAs) with 0 and 0.52 at. % nitrogen. The microstructure characterization indicated that the plastic deformation of the alloys was dominated by dislocation slip below 20% true strain. Nitrogen alloying increased the total dislocation density and the strain-hardening rate during deformation, which could be explained by the interaction between nitrogen atoms and dislocations. The higher fraction of soft orientation zones for 0.52 N HEA was conducive for strain accommodation, resulting in a reduced GND density. Hence, SSDs contributed primarily to the increase of the total dislocation density and the higher strain-hardening rate of nitrogen-doped CoCrFeMnNi.