High-entropy alloys (HEAs) usually exhibit exceptional mechanical properties attributed to one of important core effects for serious lattice strain to impede dislocation motion compared to the traditional alloys. However, their roles on the quantitative measurement for precipitate strengthening and fracture toughness are lack using the existing physical model. Here, we propose a mechanistic modelling to study effect of heterogeneous strain caused by lattice distortion on the precipitate strengthening and fracture toughness in the HEAs, and then verify this role using atomic simulation. The results indicate that the lattice distortion and precipitate synergistically impede the grain boundary migration, increasing the strength. In the dilute alloy with a low lattice distortion, the grain boundary migration process is less sensitive to the precipitate size. The stress field generated by the lattice distortion relieves the stress concentration at the crack tip under external force. This in turn alleviates the accumulation of dislocations and reduces the probability of crack extension. Furthermore, the heterogeneous strain caused by lattice distortion counteracts some of the applied stress and raises the critical stress for crack extension, which enhances the plasticity and the critical stress intensity factor. The developed unified model would be applicable to high entropy ceramics in similar scenario.

中文翻译：

---

多晶高熵合金中沉淀强化和断裂韧性的基于微观力学的通用模型

与传统合金相比，高熵合金（HEA）通常表现出优异的机械性能，这是由于严重的晶格应变阻碍位错运动的重要核心效应之一。然而，使用现有的物理模型缺乏它们对沉淀强化和断裂韧性的定量测量的作用。在这里，我们提出了一种机械模型来研究晶格畸变引起的异质应变对 HEA 中沉淀强化和断裂韧性的影响，然后使用原子模拟验证这种作用。结果表明，晶格畸变和析出物协同阻碍晶界迁移，从而提高强度。在具有低晶格畸变的稀合金中，晶界迁移过程对析出物尺寸不太敏感。晶格畸变产生的应力场缓解了外力作用下裂纹尖端的应力集中。这反过来又减轻了位错的积累并降低了裂纹扩展的可能性。此外，晶格畸变引起的异质应变抵消了部分外加应力，提高了裂纹扩展的临界应力，从而提高了塑性和临界应力强度因子。所开发的统一模型将适用于类似情况下的高熵陶瓷。