单晶体心立方金属铌裂纹尖端位错增殖行为的原位研究

单晶体心立方金属铌裂纹尖端位错增殖行为的原位研究

舒新愉¹，卢 艳¹，王立华¹，陈艳辉¹，周 浩¹，张 泽^1,2*，韩晓东^1*

（1.北京工业大学固体微结构与性能研究所，北京100124；2. 浙江大学电子显微镜中心，材料科学与工程学院，浙江 杭州310027）

摘  要  位错的增殖对体心立方金属材料的塑性性能有着非常重要的意义，目前对于体心立方位错增殖机制的动态研究主要依赖于计算模拟，实验研究很少见到报道，其位错增殖机制尚存在不确定性。本文利用透射电镜原位拉伸技术，实现了单晶体心立方金属铌（Nb）裂纹尖端位错增殖的原位动态实验观察，并提出了两个位错模型来解释位错增殖以及运动的机制。从实验上不仅证实了之前模拟的预测，而且对现有的模型进行了很好的补充，为体心立方金属材料的塑性变形机制提供了基础实验数据。

关键词  体心立方；位错增殖；单晶铌；原位

中图分类号：TB383；O711⁺.4；O77⁺.2；TG115. 21⁺ 5.3；TG115.5⁺2  文献标识码：A   doi:10.3969/j.issn.1000-6281.2017.04.003

In-situTEM investigation of dislocation multiplication in front of crack in body-centered cubic single crystal niobium

SHU Xin-yu¹，LU Yan¹，WANg Li-hua¹，CHEN Yan-hui¹，ZHOU Hao¹，

ZHANG Ze^1，2*，HAN Xiao-dong¹*

(1.Institute of Microstructure and Property of Advanced Materials，Beijing University of Technology, Beijing 100124；2. Center of Electron Microscope, Zhejiang University, Hangzhou Zhejiang 310027，China)

Abastract  Dislocation multiplication is important to the plasticity of body-centered cubic (BCC) metals. However, relevant studies mainly focused on theoretical simulations, which need further experimental evidence to support. In this work, the dislocation multiplication in front of crack in BCC single crystal Nb was revealed by in-situ transmission electron microscopy technique. Such dislocation multiplication resulted from frequent cross-slip of screw components of dislocation loops and their annihilation by dislocation interaction. A new dislocation loop can be formed during this multiplication process. Two models are provided in this work to describe the dislocation multiplication process and the new-born dislocation loop activities. Results in this work are in good agreement with previous simulations. The dislocation multiplication process in this work provides better understanding of dislocation theory of BCC metals.

Keywords  body-centered cubic; dislocation multiplication; single crystal Nb; in-situ

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