Effect of stacking fault energy on the dynamic deformation behavior of Fe_x(CoCrNi)_100-x high-entropy alloys

High-entropy alloys (HEAs) have great potential for applications under extreme loading conditions due to their excellent toughness and impact resistance. The stacking fault energy (SFE) of metallic materials essentially dominates the mechanical behavior of HEAs, but the atomic-scale mechanism of the effect of SFE on the high-speed deformation of the materials remains unclear. In this study, we systematically investigated the deformation mechanism of SFE on dynamic mechanical properties in Fe_x (CoCrNi)_100-x HEAs through a combination of experiments and molecular dynamics simulations. The results show that the intrinsic stacking fault energy (ISFE) decreases as the Fe content increases from 20% to 60%. The system with high SFE (Fe20) induces localized amorphization through the crossover of extrinsic stacking faults (ESFs), enabling it to achieve a high impact strength of 625 MPa while maintaining plasticity. However, due to frequent activation of the plane slip mechanism (including stacking faults (SFs), twinning, and reverse transformation), the impact strength of the system with low SFE is reduced to 468 MPa. The SFE-impact response correlation rule established in this study provides a theoretical basis for the design of HEAs under extreme dynamic loading scenarios.