2-13.High throughput characterization of dislocations based on 3D TEM 

Guilin Wu，Zongqiang Feng，Chengwei Lin，Rui Fu，Xiaoxu Huang

1. International Joint Laboratory for Light Alloys (MOE), College of Materials Science and Engineering, Chongqing University 400044, Chongqing
2. Shenyang National Laboratory for Materials Science, Chongqing University 400044, Chongqing

Abstract: The dislocation is an important lattice defect and exhibits a variety of characteristics with respect to its geometry, crystallography and strain energy. A three-dimensional (3D) characterization of such characteristics and their spatial distributions is crucial for the study of phase transformation and plastic deformation of metallic materials. In this presentation, a transmission electron microscopy (TEM) based three-dimensional high-throughput characterization technique was proposed to achieve a complete characterization of the three types of characteristics of dislocations. This technique was applied to quantify in 3D the geometry, crystallography and strain energy of dislocation structures in a solid solution treated and water quenched Al-Cu-Mg alloy. Combined with the use of other TEM techniques including in-situ TEM heating, high-resolution electron microscopy and electron tomography, the heterogeneous precipitation of hardening phases at dislocations during aging wasexamined with focus on the investigation of two phenomena “nucleation site selection” and “variant selection”. It is aimed to understand the underlying mechanisms and establish the general rules governing the two selection phenomena. The success of the present research can provide an innovative TEM technique for a precise and complete 3D characterization of dislocation characteristics, and enrich the theory of phase transformation associated with heterogeneous nucleation of precipitates at dislocations.

Keywords: TEM; Tomography; Dislocation; High-throughput characterization

Fig 1. Dislocation structure in quenched Al-Cu-Mg alloy.
(a) weak-beam dark filed image;(b) reconstructed dislocations in 3D, in which colours represent Burgers vectors 图 1. Al-Cu-Mg 合金中的淬火位错结构
(a) 弱束暗场像;(b) 三维重构像，其中不同颜色表示不同的柏氏矢量

      基于透射电镜的位错三维高通量表征技术

吴桂林，冯宗强，林程威，符锐，黄晓旭
1. 轻合金材料国际合作联合实验室，重庆大学材料科学与工程学院，400044，重庆

2.沈阳材料科学国家研究中心，重庆大学，400044，重庆 

摘要:作为晶体材料内部的典型晶格缺陷，位错具有多种几何、晶体学和应变能特性。位错的 形成、分布和演化与材料的晶体结构和物理性质密切相关，同时又深刻影响着材料的相变、形 变行为和诸多服役性能。深入研究位错特性与行为并在此基础上开展材料性能设计就成为材料 研究与开发中的共性基础科学问题之一。由于投影和重叠效应的影响，传统透射电镜表征方法 难以全面、同步和精确反映位错的各类几何、晶体学和应变能特征。基于透射电镜位错三维重 构技术及关联晶体学分析方法，本研究团队自主开发了高空间分辨位错三维高通量表征技术， 可以对位错的几何、晶体学和应变能特性进行全要素耦合表征。采用上述方法，研究团队对Al-Cu-Mg 合金中的淬火位错结构进行了系统定量研究(图 1)，揭示了位错环和位错螺旋的几何 特征、空间组态和分布规律，研究了典型位错环的退火演化过程，推演了位错反应的可能机理。 在此基础上，融合透射电镜原位加热分析技术，研究了位错处强化相的析出行为和规律，为进 一步丰富和发展非均匀形核条件下的相变理论提供理论依据。

关键词:位错;透射电镜;三维重构;高通量表征