In the presence of intrinsic lattice distortion and local concentration waves, high-entropy alloys (HEAs) possess unique microstructures, deformation patterns of dislocations and grain boundaries (GBs), and superior mechanical properties. In contrast to traditional crystalline metals, GBs in HEAs have been revealed to exhibit spontaneous roughening behavior, which reduces their migration ability and weakens the plastic deformability of HEAs. In addition, hydrostatic pressure (HP) treatment can modify the microstructure and deformability of GBs in HEAs, leading to enhanced strength and ductility in HEAs. In the present work, we aim to investigate the effect of HP on GB structural evolution in HEAs and reveal the HP-induced enhancement of plastic deformability via molecular dynamics (MD) simulations. Using a FeNiCrCoCu alloy as an example, we have demonstrated that the initially rough GBs in the HEA samples undergo a smoothing mechanism under the application of HP. The GB smoothing mechanism depends not only on the initial GB misorientation and microstructure, but also on temperature and GB segregation. For the <110>(113) GB, the GB roughness is featured by individual GB segments connected by atomic-scale disconnections. Under HP, the disconnections glide along the GB plane and annihilate with neighboring disconnections, reducing the roughness of the GB. For <110>(112), <110>(114), <110>(116) and <110>(223) GBs, atomic rearrangements take place in local GB segments under HP, resulting in structural adjustment and GB smoothing. These HP-induced GB smoothing mechanisms can increase the plastic deformability of GBs under shear loading. Our findings deepen the understanding of GB plasticity in HEAs and provide insights into GB engineering through HP treatment.

中文翻译：

---

静水压力介导的晶界平滑和高熵合金的塑性变形


在存在本征晶格畸变和局部集中波的情况下，高熵合金 （HEA） 具有独特的微观结构、位错和晶界 （GB） 的变形模式以及卓越的机械性能。与传统的晶体金属相比，高熵合金中的 GB 表现出自发的粗糙化行为，这降低了它们的迁移能力并削弱了高熵合金的塑性变形能力。此外，静水压力 （HP） 处理可以改变 GB 在 HEA 中的微观结构和变形能力，从而提高 HEA 的强度和延展性。在本工作中，我们旨在研究 HP 对 HEA 中 GB 结构演变的影响，并通过分子动力学 （MD） 模拟揭示 HP 诱导的塑性变形能力增强。以 FeNiCrCoCu 合金为例，我们已经证明 HEA 样品中最初粗糙的 GB 在 HP 的作用下经历了平滑机制。GB 平滑机制不仅取决于初始 GB 取向差和微观结构，还取决于温度和 GB 偏析。对于 <110>（113） GB，GB 粗糙度由原子级断开连接的各个 GB 段表示。在 HP 下，断开沿 GB 平面滑动并与相邻的断开一起湮灭，从而降低了 GB 的粗糙度。对于 <110>（112）、<110>（114）、<110>（116） 和 <110>（223） GB，在 HP 下的局部 GB 段中发生原子重排，从而导致结构调整和 GB 平滑。这些 HP 诱导的 GB 平滑机制可以提高 GB 在剪切载荷下的塑性变形能力。 我们的研究结果加深了对 HEA 中 GB 可塑性的理解，并为通过 HP 处理对 GB 工程提供了见解。