Thermodynamics and design of nanocrystalline alloys using grain boundary segregation spectra
Thermodynamics and design of nanocrystalline alloys using grain boundary segregation spectra
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DOI：
10.1016/j.actamat.2021.117177
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发表时间：
2021-09
期刊：
影响因子：
9.4
通讯作者：
M. Wagih;C. Schuh
中科院分区：
文献类型：
--
作者：
M. Wagih;C. Schuh
晶界溶质偏聚是纳米晶合金稳定化的重要机制。迄今为止，设计和筛选纳米晶稳定性的标准方法使用将GB网络视为单个实体的简化表示，并且因此使用单个“平均”偏析能量来表征合金中的溶质GB偏析。然而，这种简化未能捕获GB的高度各向异性性质，这导致分离能的谱可能非常宽。在这里，我们删除这种简化，并概述了更正式的正确的热力学标准，以筛选多晶结构的热力学稳定性，占GB的光谱性质。我们继续应用开发的标准，筛选超过200合金组合的基础上嵌入原子方法的潜力。在其优点中，这种光谱方法能够严格执行热力学第三定律，而平均偏析能量则不能。筛选的结果与实验观察基本一致。
Solute segregation at grain boundaries (GBs) is a key mechanism to stabilize nanocrystalline alloys. To date, the standard approach to design and screen for nanocrystalline stability uses a simplified representation that treats the GB network as a single entity, and thus, uses a single “average” segregation energy to characterize solute GB segregation in an alloy. This simplification, however, fails to capture the highly anisotropic nature of GBs, which results in a spectrum of segregation energies that can be very broad. Here, we remove this simplification, and outline more formally correct thermodynamic criteria to screen for thermodynamic stability of polycrystalline structures, accounting for the spectral nature of GBs. We proceed to apply the developed criteria to screen over 200 alloy combinations based on embedded atom method potentials. Among its benefits, this spectral approach enables strict enforcement of the third law of thermodynamics, where an average segregation energy does not. The results of the screening are in general agreement with experimental observations.