系统地研究了单相fcc结构等原子比CrFeNi中熵合金在应变速率10^-3~1800 s^-1，变形温度77~1073 K的拉伸力学行为。结果表明，在准静态应变速率(10^-3 s^-1)下，随着变形温度从1073 K降低到77 K，该合金的屈服应力从125 MPa提高到415 MPa，同时均匀延伸率由2%提高到82%。在673 K拉伸时材料表现出反常的均匀延伸率，这与变形过程中发生了动态应变时效相关。在恒定温度77 K下，随着应变速率从10^-3 s^-1提高到1800 s^-1，合金的强度显著提高，屈服应力从415 MPa提高到595 MPa，同时均匀延伸率保持不变，在1800 s^-1应变速率下仍可保持在68%。基于经典的ZA模型，构建了屈服应力-温度/应变速率之间的本构关系，结果表明，ZA模型可以很好地拟合和预测CrFeNi中熵合金在不同温度和应变速率下的屈服应力。基于实验结果，通过回归分析和约束优化建立了2种唯象本构模型(JC模型和KHL模型)和3种基于物理基础的本构模型(PB模型、ZA模型和NNL模型)。对比发现，JC模型和PB模型分别具有最高和最低的描述准确性。

Concentrated multicomponent alloys (CMCAs) or high/medium-entropy alloys (HEAs/MEAs) possess outstanding comprehensive properties, causing them to have the potential to be the next generation of structural materials. Phenomena occurring under dynamic tensile loading or high/low temperature of such alloys have been hardly investigated. However, its understanding is essentially needed in their application in automotive, aerospace, and military industries. Meanwhile, the suitable constitutive equations of CMCAs under such cases have been rarely investigated. In this work, the thermodynamic behavior of equiatomic CrFeNi MEA with single-phase fcc structure has been systematically investigated at strain rates from 10^-3 s^-1 to 1800 s^-1 and temperatures from 77 K to 1073 K. The results showed that as the deformation temperature decreased from 1073 K to 77 K, the yield stress was improved significantly from 125 MPa to 415 MPa. Meanwhile, the uniform elongation increased from 2% to 82%. The abnormal uniform elongation appearing at 673 K was closely related to dynamic strain aging. As the strain rate increased from 10^-3 s^-1 to 1800 s^-1 at a constant temperature of 77 K, the strength increased significantly (e.g., the yield stress increased from 415 MPa to 595 MPa), and the uniform elongation remained unchanged, still maintaining 68% at 1800 s^-1. After deformation, there were no second phases attributed to a large Ni amount in the alloys. Some deformation twins appeared at 77 K. Based on the experimental results, the relationship between yield stress and temperatures/strain rates could be successfully revealed using the ZA model. Moreover, regression analysis and constraint optimization established two phenomenological constitutive models (JC and KHL models) and three physically-based constitutive models (PB model, ZA model, and NNL model). JC and PB models had the highest and lowest description accuracy, respectively. Besides, the JC model was hard to describe the case that the work hardening decreased due to the change of temperature or strain rates, and the PB model was unsuitable in characterizing the complex work hardening behaviors.