Abstract：Precipitation-strengthened medium- and high-entropy alloys demonstrate significant potential for dynamic-loading applications, making it imperative to quantitatively elucidate their strengthening mechanisms and micro-scale deformation processes from a multi-scale perspective. This work employs a combined approach of split Hopkinson pressure bar (SHPB) dynamic compression experiments and crystal plasticity finite element (CPFE) simulations to systematically investigate the mechanical behavior and underlying microscopic mechanisms of a CoCrNiSi0.3C0.048 medium-entropy alloy over a strain rate range of 103 to 10? s?1. To elucidate the role of tertiary precipitates on dynamic mechanical response, we developed a crystal plasticity constitutive model that incorporates both the evolution of GND density and the effects of multi-scale precipitates. Results indicate that the model accurately captures the experimental stress-strain response. Hard precipitates are identified as the key agent responsible for heterogeneity in the microscopic stress field and local strain gradients, thereby promoting early-stage rapid accumulation of GNDs and markedly improving SSD storage efficiency. These two effects collectively account for the majority of the work hardening. High strain rates also amplify the strain gradient effect and dislocation multiplication through the suppression of dynamic recovery and the aggravation of dislocation pile-ups, thereby increasing the strength and hardening rate. Deformation incompatibility due to interfacial mismatches in stress, strain, and GND density was then quantitatively assessed at the grain scale.
2026, Vol. 47 
