Vacancy diffusion in multi-principal element alloys: The role of chemical disorder in the ordered lattice
Vacancy diffusion in multi-principal element alloys: The role of chemical disorder in the ordered lattice
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DOI：
10.1016/j.actamat.2020.06.022
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发表时间：
2020-09-01
期刊：
影响因子：
9.4
通讯作者：
Patala, Srikanth
中科院分区：
文献类型：
--
作者：
Thomas, Spencer L.;Patala, Srikanth
多主元合金 (MPEA) 的许多据称优点，例如耐腐蚀、高温氧化和耐辐照性，都对空位扩散率高度敏感。类似地，溶质相互扩散受空位扩散控制。通常还不清楚 MPEA 是否真正稳定或通过缓慢相互扩散有效稳定。这些合金所提供的相当大的成分空间使得优化所需性能成为一项艰巨的任务；理论和计算工具对于指导合金开发是必要的。对于扩散，此类工具取决于对给定合金内空位迁移势垒的了解以及对这些势垒如何影响空位扩散率的理解。我们提出了崎岖能源景观中空位扩散的广义理论，并结合 MPEA 空位扩散的动力学蒙特卡罗模拟。势垒能统计数据是通过等原子 CoNiCrFeMn 合金中的微动弹性带计算得出的。理论和模拟表明，固溶体 MPEA 中的空位扩散不一定缓慢，但可以进行调整，并且陷阱模型不足以解释 CoNiCrFeMn HEA 中的缓慢扩散。这些结果还表明，任何试图忠实代表扩散相关现象的模型都必须考虑能源景观的全部性质，而不仅仅是迁移障碍。 (C) 2020 Acta Materialia Inc. 由 Elsevier Ltd 出版。保留所有权利。
Many of the purported virtues of Multi-Principal Element Alloys (MPEAs), such as corrosion, high-temperature oxidation and irradiation resistance, are highly sensitive to vacancy diffusivity. Similarly, solute interdiffusion is governed by vacancy diffusion. It is also often unclear whether MPEAs are truly stable or effectively stabilized by slow interdiffusion. The considerable composition space afforded to these alloys makes optimizing for desired properties a daunting task; theoretical and computational tools are necessary to guide alloy development. For diffusion, such tools depend on both a knowledge of the vacancy migration barriers within a given alloy and an understanding of how these barriers influence vacancy diffusivity. We present a generalized theory of vacancy diffusion in rugged energy landscapes, paired with Kinetic Monte Carlo simulations of MPEA vacancy diffusion. The barrier energy statistics are informed by nudged elastic band calculations in the equiatomic CoNiCrFeMn alloy. Theory and simulations show that vacancy diffusion in solid-solution MPEAs is not necessarily sluggish, but can potentially be tuned, and that trap models are an insufficient explanation for sluggish diffusion in the CoNiCrFeMn HEA. These results also show that any model that endeavors to faithfully represent diffusion-related phenomena must account for the full nature of the energy landscape, not just the migration barriers. (C) 2020 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.