The effect of temperature and strain rates on microstructure development of a typical polycrystalline CoCrFeMnNi high-entropy alloy was conducted in the molecular dynamics study. Four typical temperatures of 77 K, 300 K, 700 K and 1100 K were selected. The results revealed that the peak stress and the flow stress decreased with the increases in formation temperatures, while the extent of twinning was found to be responsive to the temperatures. The temperature-linked differences in the growth velocity of intrinsic stacking were observed. Furthermore, three strain rates of 1 × 10 8 s −1 , 5 × 10 8 s −1 , and 1 × 10 9 s −1 were chosen to explore the influence of strain rate on the microstructural behavior of the material at 300 K. It was found that both peak stress and flow stress increased with the strain rates. The FCC → HCP phase transformation and parallel twin formation were observed as the response to plastic deformation of the material. The simulation shows that the twinning controls the inelastic deformation at low temperatures and high strain rates. With the increase in temperature and a reduction in strain rate, dislocation slipping is the main reason for the plasticity.

中文翻译：

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基于分子动力学的温度和应变速率对纳米晶 CoCrFeMnNi 高熵合金变形影响的分析

在分子动力学研究中进行了温度和应变速率对典型多晶 CoCrFeMnNi 高熵合金微观结构发展的影响。选择了 77 K、300 K、700 K 和 1100 K 四个典型温度。结果表明，峰值应力和流动应力随着地层温度的升高而降低，而孪晶程度对温度有响应。观察到与温度相关的固有堆叠生长速度的差异。此外，选择了 1 × 10 8 s -1 、5 × 10 8 s -1 和 1 × 10 9 s -1 三种应变率来探索应变率对材料在 300 K 下微观结构行为的影响。发现峰值应力和流动应力都随着应变速率的增加而增加。观察到 FCC → HCP 相变和平行孪晶形成是对材料塑性变形的响应。模拟表明，孪晶控制了低温和高应变率下的非弹性变形。随着温度的升高和应变速率的降低，位错滑移是产生塑性的主要原因。