In this study, mechanical tests were conducted on a face-centered cubic FeCoNiCrMn high-entropy alloy, both in tension and compression, in a wide range of strain rates (10⁻⁴–10⁴ s⁻¹) to systematically investigate its dynamic response and underlying deformation mechanism. Materials with different grain sizes were tested to understand the effect of grain size, thus grain boundary volume, on the mechanical properties. Microstructures of various samples both before and after deformation were examined using electron backscatter diffraction and transmission electron microscopy. The dislocation structure as well as deformation-induced twins were analyzed and correlated with the measured mechanical properties. Plastic stability during tension of the current high-entropy alloy (HEA), in particular, at dynamic strain rates, was discussed in lights of strain-rate sensitivity and work hardening rate. It was found that, under dynamic conditions, the strength and uniform ductility increased simultaneously as a result of the massive formation of deformation twins. Specifically, an ultimate tensile strength of 734 MPa and uniform elongation of ∼63% are obtained at 2.3 × 10³ s⁻¹, indicating that the alloy has great potential for energy absorption upon impact loading.

在这项研究中，在广泛的应变率范围内（10 ⁻⁴ –10 ⁴  s ⁻¹) 系统地研究其动态响应和潜在的变形机制。对具有不同晶粒尺寸的材料进行了测试，以了解晶粒尺寸（即晶界体积）对机械性能的影响。使用电子背散射衍射和透射电子显微镜检查变形前后各种样品的微观结构。分析了位错结构以及变形引起的孪晶，并将其与测量的机械性能相关联。目前的高熵合金 (HEA) 在拉伸过程中的塑性稳定性，特别是在动态应变率下，根据应变率敏感性和加工硬化率进行了讨论。结果发现，在动态条件下，由于变形孪晶的大量形成，强度和均匀延展性同时增加。具体而言，在 2.3 × 10³  s ^-1，表明该合金在冲击载荷下具有很大的能量吸收潜力。