Refractory high-entropy alloys (RHEAs) are considered as potential candidates for high-temperature applications, with the glide resistance of edge dislocations being a crucial factor in determining the high-temperature strength. However, the solid-solution strengthening mechanism of edge dislocations in RHEAs is not fully understood. The existing Labusch-type models mainly focus on the long-range interaction of solute atoms with the dislocation stress field, while there is little attention paid to the short-range interaction in the dislocation core region. Here, we conduct carefully designed atomic simulations to decouple the long-range and short-range interactions in a typical RHEA, NbMoTaW. Furthermore, the total change in solute-dislocation interaction energy is decomposed, and a hierarchical energy landscape is revealed, demonstrating that the short-range interaction at the core region gains more importance in the solid-solution strengthening of edge dislocations in NbMoTaW. Then, we determine the Larkin length, which signifies the transition from size-dependent to size-independent dislocation behavior. The activation barrier extracted from the simulation with the dislocation length above the Larkin length is incorporated into the crystal plasticity model, and the high-temperature yield strength is well predicted by the strengthening from edge dislocations. Our work provides deep insight into the solid-solution strengthening mechanism in random solution solids, elucidating the importance of the local atomic configuration around the dislocation core.

中文翻译：

---

难熔高熵合金中边缘位错滑动的多级能量景观


难熔高熵合金 （RHEAs） 被认为是高温应用的潜在候选者，边缘位错的滑动阻力是决定高温强度的关键因素。然而，RHEA 中边缘位错的固溶强化机制尚不完全清楚。现有的 Labusch 型模型主要关注溶质原子与位错应力场的长程相互作用，而很少关注位错核心区域的短程相互作用。在这里，我们进行了精心设计的原子仿真，以解耦典型 RHEA、NbMoTaW 中的远程和短程相互作用。此外，溶质-位错相互作用能的总变化被分解，并揭示了分层能量景观，表明核心区域的短程相互作用在 NbMoTaW 边缘位错的固溶强化中变得更加重要。然后，我们确定 Larkin 长度，它表示从大小依赖到尺寸无关的位错行为的转变。从位错长度高于 Larkin 长度的仿真中提取的激活势垒被纳入晶体塑性模型，并且通过边缘位错的强化很好地预测了高温屈服强度。我们的工作为随机固溶体固体中的固溶体强化机制提供了深入的见解，阐明了位错核心周围局部原子构型的重要性。