电镜成像方式对数字散斑相关方法结果的影响

Effect of Imaging Mode of Scanning Electron Microscope on the Results of Digital Speckle Correlation Method

研究了扫描电镜成像方式对数字散斑相关方法计算结果的影响,在此基础上对等离子喷涂铜涂层的变形场进行分析。结果表明二次电子成像和背散射电子成像的机理不同,应用时需要以相关系数及其标准差为标准,选取更为合适的成像方式。通过数字散斑相关方法显化了等离子喷涂铜涂层在加载过程中的应变场,结果表明随加载力增加,裂纹尖端应变场逐渐由蝴蝶状区域转为圆形钝化区。

Effect of imaging mode of scanning electron microscope （SEM） is investigated on the computation results of digital speckle correlation （DSC） method. The strain distribution on plasma sprayed copper coatings is analyzed based on the results. It shows that the imaging mechanisms are different for the secondary electron imaging mode and backscattered electron imaging mode. Correspondingly, the data of correlation coefficient and its standard deviation, obtained from the computation using DSC method, should be used as the criterion for selecting the proper imaging mode of SEM. The strain distribution of plasma sprayed coatings is characterized using the DSC method. The shape o~ the strain concentration zone at the cracking tip changes from butterfly-like to circle-like.