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单晶铌低温剪切带形成与演化的透射电镜研究

李习耀，刘皓岚，翟晓玉，王江伟*
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2024年 第43卷 第5期: 1000-6281（2024）05-557-007     下载地址：

单晶铌低温剪切带形成与演化的透射电镜研究

李习耀，刘皓岚，翟晓玉，王江伟*

（1.河南省科学院材料研究所，河南郑州450046；2.浙江大学材料科学与工程学院，硅及先进半导体材料全国重点实验室，电子显微镜中心，浙江杭州310027）

摘  要  作为高度局域化变形的重要塑性载体，低温剪切带通常会导致材料塑性失稳。研究其形成与演化机制对材料低温服役可靠性具有重要意义。本文对不同取向单晶铌的低温剪切带行为展开系统探究。研究表明，位错在不同滑移面的局域化活动导致了{110}或{112}剪切带的形成，并使材料宏观上表现出低温塑性失稳特征，其力学曲线表现出应力骤降的塑性流变特征。其形成与位错局部滑移有关。随着剪切带持续增厚，其界面处集聚的位错密度也随之升高，使剪切带-基体取向差逐渐增大；当增厚到微米尺寸后，剪切带界面位错所能协调的两侧晶体取向差趋于饱和。这些结果为发展低温剪切带演化动力学模型提供了实验参照。

关键词  铌；低温剪切带；塑性失稳；应力骤降；界面位错

中图分类号：TG14；TG115.21+5.3       文献标识码：A    doi：10.3969/j.issn.1000-6281.2024.05.005

   

Formation and evolution of shear band in single crystal niobium deformed at low temperature based on TEM study

LI Xiyao1, LIU Haolan1, ZHAI Xiaoyu2, WANG Jiangwei2*

(1. Institue of Materials, Henan Academy of Sciences, Zhengzhou Henan 450046；2.Center of Electron Microscopy, State Key Laboratory of Silicon and Advanced Semiconductor Materials, School of Materials Science and Engineering, Zhejiang University, Hangzhou Zhejiang 310027, China)

Abstract  The investigation of low-temperature shear band is crucial due to their role as significant plastic carriers of highly localized deformation, often resulting in material plastic instability. Understanding the mechanisms behind their formation and evolution mechanisms is essential for ensuring the service safety of materials.

This paper focused on examining the behavior of shear banding in single crystal niobium with varying orientations. The findings revealed that localized dislocation activities on different slip planes led to the development of {110} or {112} shear bands. This resulted in macro-level plastic instability, as evidenced by sudden stress drops in the material's mechanical curves. The formation of shear bands was associated with the localized movement of dislocations. As the shear band thickened over time, the dislocation intensity at the interface also rose, leading to increasing misorientation between the shear band and the surrounding matrix. Once the thickness reached the micron scale, the misorientation that can be accommodated by the interfacial dislocations tended to saturate. These empirical findings offer valuable insights for advancing dynamics models of low-temperature shear bands.

Keywords   niobium; low-temperature shear band; plastic instability; stress drop; interfacial dislocation

 

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