CrMnFeCoNi high-entropy alloys (HEA) with various microstructures have been produced using cold rolling followed by critical annealing at various temperatures. Shear deformation behaviors of this HEA with various microstructures at a wide range of strain rates (2 × 10^-3-5 × 10⁴ s^-1) have been characterized using hat-shaped specimens. Strain hardening exponent and strain rate sensitivity have been obtained for various microstructures. No shear localization was observed up to shear strain of 8 for all microstructures under lower strain rates (2 × 10^-3-1 × 10¹ s^-1), while stress drop and shear localization were found to occur at various critical shear strains for various microstructures under dynamic shear loading (5 × 10⁴ s^-1). A new formula, considering competition of strain hardening and strain rate hardening against thermal softening, was proposed to estimate the critical shear strains under dynamic shear loading and the predicted results were found to be in a fairly good agreement with the experimental data. Based on micro-hardness testing, the strain hardening due to the microstructure evolution was found be much stronger under dynamic shear loading than that under quasi-static loading at the same interrupted shear strain, which can be attributed to the more efficient grain refinement and the triggered hierarchical deformation nanotwins under dynamic shear deformation.

使用冷轧，然后在各种温度下进行临界退火，可以生产出具有各种微观结构的CrMnFeCoNi高熵合金（HEA）。使用帽子形试样表征了具有各种微观结构的该HEA在较宽的应变速率范围（2×10 ^-3 -5×10 ⁴ s ^-1）下的剪切变形行为。对于各种微观结构，已经获得了应变硬化指数和应变速率敏感性。在较低的应变速率（2×10 ^-3 -1×10 ¹ s ^-1）下，对于所有微观结构，未观察到剪切应变高达8的剪切局部化），而在动态剪切载荷（5×10 ⁴ s ^-1）下，对于各种微观结构，在各种临界剪切应变下会出现应力下降和剪切局部化）。提出了考虑应变硬化和应变速率硬化与热软化的竞争关系的新公式，以估计动态剪切载荷下的临界剪切应变，并且预测结果与实验数据相当吻合。根据显微硬度测试，在相同的剪切应变下，动态剪切载荷下的微观结构演变导致的应变硬化要比准静态载荷下的强得多，这可以归因于更有效的晶粒细化和晶粒的细化。在动态剪切变形下触发了分层变形纳米孪晶。