Adiabatic shear localization induced by dynamic recrystallization in CoCrFeNi high-entropy alloy under shaped charge acceleration

High-entropy alloys (HEAs) are considered promising candidates for extreme loading conditions. However, the deformation behavior and underlying microscopic mechanisms at ultrahigh strain rates remain incompletely understood. Here, the sheet shaped charge configuration was employed to successfully recover CoCrFeNi HEA liners deformed at a strain rate on the order of 10 5 s -1 . Microscopic observations reveal that the CoCrFeNi HEA liner forms adiabatic shear bands under ultra-high strain rate loading. Spatial comparisons across different deformation zones showed that dynamic recrystallization (DRX) plays a key role in the formation of adiabatic shear bands in the alloy. Specifically, two dynamic recrystallization behaviors were observed as pathways for recrystallized grain nucleation: twin-induced dynamic recrystallization (TDRX) and discontinuous dynamic recrystallization (DDRX). These findings provide valuable insights into the plastic deformation mechanisms of the CoCrFeNi HEA under ultra-high strain rate and clarify the localization failure tendency of CoCrFeNi HEA liners during the jet forming process.