arXiv 2403.032822024-03-05cond-mat.mtrl-sci

Ni$_{75}$Al$_{25}$中能垒的第一性原理验证

First Principles Validation of Energy Barriers in Ni$_{75}$Al$_{25}$

Adam Fisher, Julie B. Staunton, Huan Wu, Peter Brommer

备注：: 18 pages, 11 figures
DOI：: 10.1088/1361-651X/ad5c85

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AI总结：

本研究针对镍基高温合金析出相KMC模拟的能垒可靠性问题，通过第一性原理方法验证ARTn得到的Ni₇₅Al₂₅空位迁移能垒，构建连续验证链，发现现有原子间势均无法满足KMC模拟的能垒精度要求。

摘要：

镍基高温合金中的析出相在热处理过程中形成的时间尺度是直接分子动力学模拟无法企及的，但可通过动力学蒙特卡洛（kinetic Monte Carlo, KMC）方法开展研究，这就需要获取系统轨迹上分隔不同构型的能垒的可靠数值。本研究针对含单空位的部分有序Ni$_{75}$Al$_{25}$体系，将采用新型活化弛豫技术（Activation-Relaxation Technique nouveau, ARTn）方法得到的空位迁移能垒，与已发表的原子间相互作用势的计算结果、以及第一性原理方法的结果进行对比验证。第一步，我们证实ARTn方法得到的能垒与用弹性带法（nudged elastic band, NEB）测定的能垒一致。由于这些计算中使用的原子数量过多，无法直接开展从头算，我们随后将晶胞尺寸缩减至255个原子，以此控制有限尺寸效应。接着我们在缩小后的晶胞中，使用平面波密度泛函理论（density functional theory, DFT）程序包CASTEP及其内置的NEB方法进行计算。这为我们提供了一条从第一性原理到采用原子间势的动力学蒙特卡洛模拟的连续验证链。随后我们用NEB方法评估了另外五种原子间势的能垒，结果表明没有一种势能够以足够的可靠性给出适用于KMC模拟的能垒，其中部分势函数完全失效。这项工作是量化析出相形成与演化的KMC模拟中所产生误差的第一步。

英文摘要：

Precipitates in Nickel-based superalloys form during heat treatment on a time scale inaccessible to direct molecular dynamics simulation, but could be studied using kinetic Monte Carlo (KMC). This requires reliable values for the barrier energies separating distinct configurations over the trajectory of the system. In this study, we validate vacancy migration barriers found with the Activation-Relaxation Technique nouveau (ARTn) method in partially ordered Ni$_{75}$Al$_{25}$ with a monovacancy using published potentials for the atomic interactions against first-principles methods. In a first step, we confirm that the ARTn barrier energies agree with those determined with the nudged elastic band (NEB) method. As the number of atoms used in those calculations is too great for direct ab initio calculations, we then cut the cell size to 255 atoms, thus controlling finite size effects. We then use the plane-wave density functional theory (DFT) code CASTEP and its inbuilt NEB method in the smaller cells. This provides us with a continuous validation chain from first principles to kinetic Monte Carlo simulations with interatomic potentials. We then evaluate the barrier energies of five further interatomic potentials with NEB, demonstrating that none yields these with sufficient reliability for KMC simulations, with some of them failing completely. This is a first step towards quantifying the errors incurred in KMC simulations of precipitate formation and evolution.

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