Multi-principal element solid solutions are prone to develop local chemical inhomogeneities, e.g., chemical order/clustering and/or compositional undulation. To model the structural transformation of complex multi-principal element alloys (MPEAs), a flexible pairwise-energy model is developed. Lattice Monte Carlo (MC) simulations, coupled with discrete atomic pair energies, are extensively conducted to investigate thermodynamic atomic structures of NiCoFe-based alloys. The results of simulations are consistent with reported experimental data and provide insights into phase decomposition, species segregation/preferences, and chemical order/disorder. The simulations also offer microscopic views of atomic segregation by incorporating small atom (e.g., Boron) at grain boundaries. By employing Cahn’s wetting theory, the observed phase transformation processes, ranging from perfect to partial/pre-wetting, are explained and validated thermodynamically by the model. The current approach has the potential to be extended to a variety of MPEA systems with constant lattices.

中文翻译：

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NiCoFeAlTiB 多主元素合金的化学有序/无序相变：蒙特卡罗分析


多主元素固溶体容易产生局部化学不均匀性，例如化学有序/聚集和/或成分波动。为了模拟复杂多主元素合金 （MPEA） 的结构转变，开发了一种灵活的成对能量模型。晶格蒙特卡洛 （MC） 仿真与离散原子对能量相结合，被广泛用于研究 NiCoFe 基合金的热力学原子结构。模拟结果与报告的实验数据一致，并提供了对相分解、物种分离/偏好和化学顺序/无序的见解。这些模拟还通过在晶界掺入小原子（例如硼）来提供原子偏析的微观视图。通过使用 Cahn 的润湿理论，模型解释了和验证了观察到的相变过程，从完美到部分/预润湿。目前的方法有可能扩展到各种具有常晶格的 MPEA 系统。