高时空分辨率下大块非晶剪切带形成机理的实验研究

项目名称： 高时空分辨率下大块非晶剪切带形成机理的实验研究

项目编号： No.11202168

项目类型： 青年科学基金项目

立项/批准年度： 2013

项目学科： 数理科学和化学

项目作者： 侯兵

作者单位： 西北工业大学

项目金额： 28万元

中文摘要： 大块非晶具有优异的力学性能，然而其在室温条件下表现出的非均匀流动和剪切失稳破坏成为制约其应用的一个严重障碍，因此对大块非晶剪切变形机理的研究成为目前国际上的一个研究热点。本项目从实验角度出发，对带初始缺陷的大块非晶试样分别进行动态压缩和静态原位SEM拉伸实验，结合高分辨率超高速照相技术和相关图像显形分析技术获得与剪切带演化特征时间相当的精细时间描述，对剪切带扩展规律及扩展速度进行研究；另外，利用原位SEM加载和DIC相结合的分析技术，在空间域上获得剪切带的高分辨率特征图像，获得分阶段加载大块非晶试样剪切变形区域的位移场及特征尺寸信息。本项目旨在发展一种具有较高时间和空间分辨率，可对剪切带几何尺寸、扩展速度和扩展方式等进行直观测量和分析计算的实验方法，该项研究对于理解剪切带形成和扩展过程，揭示非晶态合金的剪切变形机理具有重要意义。

中文关键词： 非晶合金；剪切带；原位SEM；高速拍照；数字图像相关

英文摘要： Bulk metallic glass has attracted much interest because of its excellent mechanical properties. However, it undergoes inhomogenous flow at room temperature and fracture with shear instability at very small plastic strain,which restricts its otherwise desireable mechanical properties as well as its potential applications. In this study, we are going to investigate the shear behavior of metallic glass by performing dynamic compression and quasi-static in-situ SEM tension tests on some notched rectangular specimens. High-speed imaging technique combined with Digital Image Correlation(DIC) and fusible coating delomorphic method are employed to obtain the detailed description on the initiation and evolution of metallic glass shear bands with highly temporal resolution. This experiment focuses on verifing the two possible propagating manners of shear bands, i.e. simultaneous manner and progressive manner, and whereafter estimating the propagation speed of shear band. Besides the dynamic test with high-speed camera, DIC is also combined with highly resolved SEM images obtained at different loading period of in-situ SEM tension test. The purpose of this study is to obtain quantitatively the displacement field of shear banding zone and to investigate the characteristic dimensions of shear band with sufficient spatial

英文关键词： metallic glass；shear band；in-situ SEM；high-speed photography；Digital Image Correlations