The exceptional combination of strength and ductility in multi-component alloys is often attributed to the interaction of dislocations with the various solute atoms in the alloy. To study these effects on the mechanical properties of such alloys there is a need to develop a modeling framework capable of quantifying the effect of these solutes on the evolution of dislocation networks. Large scale three-dimensional (3D) Discrete dislocation dynamics (DDD) simulations can provide access to such studies but to date no relevant approaches are available that aim for a complete representation of real alloys with arbitrary chemical compositions. Here, we introduce a formulation of dislocation interaction with substitutional solute atoms in fcc alloys in 3D DDD simulations that accounts for solute strengthening induced by atomic misfit as well as fluctuations in the cross-slip activation energy. Using this model, we show that local fluctuations in the chemical composition of various CrFeCoNi-based multi-principal element alloys (MPEA) lead to sluggish dislocation motion, frequent cross-slip and alignment of dislocations with solute aggregation features, explaining experimental observations related to mechanical behavior and dislocation activity. It is also demonstrated, that this behavior observed for certain MPEAs cannot be reproduced by assuming a perfect solid solution. The developed method also provides a basis for further investigations of dislocation plasticity in any real arbitrary fcc alloy with substitutional solutes.

多组分合金中强度和延展性的特殊组合通常归因于位错与合金中各种溶质原子的相互作用。为了研究这些对此类合金机械性能的影响，需要开发一个能够量化这些溶质对位错网络演变的影响的建模框架。大规模三维 (3D) 离散位错动力学 (DDD) 模拟可以提供对此类研究的访问，但迄今为止还没有相关方法可用于完整表示具有任意化学成分的真实合金。这里，我们在 3D DDD 模拟中引入了与 fcc 合金中置换溶质原子的位错相互作用公式，该公式解释了由原子错配引起的溶质强化以及交叉滑移激活能的波动。使用该模型，我们表明各种 CrFeCoNi 基多主元素合金 (MPEA) 的化学成分的局部波动导致位错运动缓慢、频繁的交叉滑移和具有溶质聚集特征的位错排列，解释了与力学行为和位错活动。还证明，对于某些 MPEA 观察到的这种行为无法通过假设完美的固溶体来重现。