A taxonomy of grain boundary migration mechanisms via displacement texture characterization
A taxonomy of grain boundary migration mechanisms via displacement texture characterization
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DOI：
10.1016/j.actamat.2021.117425
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发表时间：
2021-08
期刊：
影响因子：
9.4
通讯作者：
I. Chesser;B. Runnels;Elizabeth A. Holm
中科院分区：
文献类型：
--
作者：
I. Chesser;B. Runnels;Elizabeth A. Holm
原子模拟提供了目前可用的最详细的晶界（GB）迁移图片。然而，从原子模拟数据中提取单元机制是困难的，因为动物园的竞争，几何复杂的3D原子重排过程。在这项工作中，我们介绍了位移纹理表征框架，用于分析原子重排事件在GB迁移，结合滑移矢量分析，bicillarallography和最佳运输的想法。介绍了位移数据的两种分解方法：剪切混洗分解和最小混洗分解。前者用于从剪切耦合迁移轨迹中提取洗牌模式，后者用于分析温度依赖的洗牌机制。作为位移织构框架的应用，我们表征了晶体学上不同的一组移动的GB在FCC Ni双晶中的洗牌机制的GB几何结构依赖性。该分析的两个科学贡献包括：1）通过亚稳态GB几何解释了洗牌模式的边界平面依赖性; 2）多模态约束GB迁移机制的分类，其中可能包括多个竞争洗牌模式、周期加倍效应、不同的滑动和剪切耦合事件以及GB自扩散。
Atomistic simulations provide the most detailed picture of grain boundary (GB) migration currently available. Nevertheless, extracting unit mechanisms from atomistic simulation data is difficult because of the zoo of competing, geometrically complex 3D atomic rearrangement processes. In this work, we introduce the displacement texture characterization framework for analyzing atomic rearrangement events during GB migration, combining ideas from slip vector analysis, bicrystallography and optimal transportation. Two types of decompositions of displacement data are described: the shear-shuffle and min-shuffle decomposition. The former is used to extract shuffling patterns from shear coupled migration trajectories and the latter is used to analyze temperature dependent shuffling mechanisms. As an application of the displacement texture framework, we characterize the GB geometry dependence of shuffling mechanisms for a crystallographically diverse set of mobile GBs in FCC Ni bicrystals. Two scientific contributions from this analysis include 1) an explanation of the boundary plane dependence of shuffling patterns via metastable GB geometry and 2) a taxonomy of multimodal constrained GB migration mechanisms which may include multiple competing shuffling patterns, period doubling effects, distinct sliding and shear coupling events, and GB self diffusion.