Abstract

Constitutive modeling of CoCrFeMnNi high-entropy alloy (HEA) at cryogenic temperature (77 K) and room temperature (293 K) has been investigated. The effect of temperature on deformation behavior such as twinning, forest hardening, and back stress hardening has been established. The enhanced ductility and strength of CoCrFeMnNi HEA at 77 K are due the combination of sub-grain structure, twinning, and dislocations. This phenomenon is explained in terms of quantitative values of twin volume fraction, inter-twin spacing, and dislocation density. The isotropic kinematic constitutive model is constructed with a critical twinning stress parameter to obtain the criteria for twinning initiation. The developed finite element model simulation results at 77 K and 293 K are in good agreement with the experimental data. The model displays a smooth increase in the twin volume fraction until fracture point (maximum twin fraction region). Also, different modeling parameters are obtained for each temperature to account for the changing deformation behavior.

Graphic Abstract

中文翻译：

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低温和室温下CoCrFeMnNi高熵合金的临界孪晶应力本构模型。

摘要

研究了CoCrFeMnNi高熵合金（HEA）在低温（77 K）和室温（293 K）下的本构模型。已经确定了温度对变形行为（如孪生，森林硬化和背应力硬化）的影响。CoCrFeMnNi HEA在77 K时增强的延展性和强度归因于亚晶粒结构，孪晶和位错的结合。用孪晶体积分数，孪晶间间距和位错密度的定量值解释了这种现象。利用临界孪生应力参数构建各向同性运动本构模型，以获得孪生引发的标准。所开发的有限元模型在77 K和293 K上的仿真结果与实验数据非常吻合。该模型显示孪晶体积分数的平滑增加，直到断裂点（最大孪晶分数区域）。而且，针对每个温度获得了不同的建模参数，以说明变化的变形行为。

图形摘要