3D arrangement of atomic polyhedra in tilt grain boundaries
3D arrangement of atomic polyhedra in tilt grain boundaries
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DOI：
10.1016/j.actamat.2020.10.017
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发表时间：
2021-01-01
期刊：
影响因子：
9.4
通讯作者：
Ikuhara, Yuichi
中科院分区：
文献类型：
--
作者：
Inoue, Kazutoshi;Kawahara, Kazuaki;Ikuhara, Yuichi
在有记录的历史中，多晶材料一直被使用，它们的宏观性能强烈地依赖于其晶体结构中的缺陷。晶界(GB)的独特性质应该来自附近的纳米尺度空间，这导致了关于填充GB区域的原子多面体的类型以及通用结构单元集的问题。揭示GB结构多面体排列的基本数学框架和确定多晶材料中结构-性质关系的起源是至关重要的，这是设计高性能材料的一个基本方面，但也是重要的。本文分析了面心立方(FCC)晶体中[001]、[110]和[111]对称倾斜带的三维原子结构，其中多面体单元是严格定义的，而不是2D结构单元模型中的多边形排列。得出的结论是，GB区域只能由体积或GB类型的多面体单元填充，且变化较小。在本研究中，定量地确定了原子多面体在GBS周围的三维排列，并通过数值分析对其进行了系统的描述。此外，Gb的层次结构直接遵循由修正的Farey图表示的有理数的分布，该图代表了面心立方晶体中对称倾斜Gb的三维原子结构。奇异GB的定义是指最多由两类多面体单元包装的GB，任何GB都可以由构成奇异GB的多面体单元包装。(C)2020 Acta Materialia Inc.由爱思唯尔有限公司出版。版权所有。
Polycrystalline materials have been used throughout the recorded history, and their macroscopic properties strongly depend on the defects in their crystalline structures. Unique properties of the grain boundaries (GBs) should result from nearby nano-scale space, leading to the questions regarding the type of atomic polyhedra that pack the GB region as well as the universal set of structural units. It is essential to reveal the underlying mathematical framework for the polyhedral arrangement of GB structures and identify the origin of structure-property relationships in polycrystalline materials, which is a fundamental aspect but important for designing high-performance materials. Herein, 3D atomic structures of [001], [110], and [111] symmetrical tilt GBs are analyzed in the face-centered cubic (fcc) crystals, where the polyhedral units are rigorously defined in contrast to the polygonal arrangement within the 2D structural unit model. It is concluded that the GB region can only be packed by the bulk or GB-type polyhedral units with minor variations. In this study, the 3D arrangement of atomic polyhedra around the GBs is quantitatively determined and systematically described by numerical analysis. Moreover, the GB hierarchy directly follows the distribution of rational numbers that is represented by the modified Farey diagram, which represents the 3D atomic structure of the symmetrical tilt GBs in an fcc crystal. The definition of singular GB is proposed as the GB packed by at the most two types of polyhedral units, and any GB can be packed by the polyhedral units that form the singular GBs. (C) 2020 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.