A Lie-algebra-based description of disclination densities and the quantification of partial disclinations in deformed polycrystalline metals
A Lie-algebra-based description of disclination densities and the quantification of partial disclinations in deformed polycrystalline metals
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DOI：
10.1016/j.actamat.2023.119176
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发表时间：
2023-07
期刊：
影响因子：
9.4
通讯作者：
Chunfeng Du;Yipeng Gao;Yizhen Li;M. Zha;Peng Chen;Y. Sheng;Heng-Nan Liang;Hong Wang
中科院分区：
文献类型：
--
作者：
Chunfeng Du;Yipeng Gao;Yizhen Li;M. Zha;Peng Chen;Y. Sheng;Heng-Nan Liang;Hong Wang
晶体缺陷（例如，位错、向错和晶界）在确定金属材料的机械和功能性质中起关键作用。从物理的角度来看，位错和向错是晶体中两种基本的拓扑缺陷，它们分别源于平移对称和旋转对称的破缺。尽管在文献中对位错进行了广泛的研究，但向错对金属机械性能的影响尚未得到很好的认识，部分原因是缺乏对向错旋转性质的适当描述。在这里，我们提出了一种基于李代数的方法来量化旋转属性的向错，这导致了一个方便的方法来确定向错密度分布直接从电子背散射衍射数据。通过准原位电子背散射衍射表征，确定了变形多晶镁合金中向错的三种主要形成机制，位错-晶界相互作用、位错再分布和孪晶-孪晶反应，所有这些都可以在一个通用的框架下被视为各种类型缺陷之间的拓扑反应。我们的工作不仅为研究多种晶体缺陷之间的相互作用和反应提供了一种新的数学工具，而且为基于位错/向错理论理解金属和合金的变形行为提供了一种新的见解。
Crystalline defects (e.g., dislocations, disclinations and grain boundaries) play a critical role in determining the mechanical and functional properties of metallic materials. From a physical point of view, dislocations and disclinations are the two fundamental types of topological defects in crystals, which originate from the breaking of translational symmetry and rotational symmetry, respectively. In spite of extensive studies on dislocations in the literature, the effects of disclinations on mechanical properties of metals have not been well recognized, partially due to the lack of an appropriate description for the rotational nature of disclinations. Here we suggest a Lie-algebra-based method to quantify the rotational properties of disclinations, which leads to a convenient way to determine disclination density distribution directly from Electron Backscatter Diffraction data. Throughquasi-in-situElectron Backscatter Diffraction characterizations, three major formation mechanisms of disclinations have been identified in deformed polycrystalline Mg alloys, i.e., dislocation-grain boundary interaction, dislocation redistribution and twin-twin reaction, all of which can be treated as topological reactions among various types of defects under a general framework. Our work not only suggests a new mathematical tool to investigate the interactions and reactions among multiple types of crystalline defects, but also provides a new insight to understand the deformation behaviors of metals and alloys based on dislocation/disclination theory.