大面积EBSD分析中的标定准确性探究  

Research on index accuracy in large area EBSD analysis

作　　者：郜鲜辉[1] 黄高 GAO Xian-hui;HUANG Gao(Aanlytical and Testing Center,Huazhong University of Science and Technology,Wuhan Hubei 430074;Wuhan National Laboratory for Optoelectronics,Wuhan Hubei 430074,China)

机构地区：[1]华中科技大学分析测试中心,湖北武汉430074 [2]武汉光电国家研究中心,湖北武汉430074

出　　处：《电子显微学报》2021年第5期609-615,共7页Journal of Chinese Electron Microscopy Society

基　　金：国家重点研发计划(No.2017UFB1103800)。

摘　　要：在低倍率下对样品进行大面积EBSD测试时,常发现边缘区域标定率较低。为探究大面积EBSD分析中标定率低的影响因素,本文在100倍下选取同一采集区域,将其移至视野不同位置进行EBSD数据采集,结果表明,在测试参数不变的情况下,同一采集区域在不同位置时的标定率差别很大。甚至同一晶粒在不同位置采集时标定的取向也存在差异。分析发现,标定结果存在差异的主要原因是低倍率下,在视野中心电子束处于聚焦状态,而在边缘位置电子束处于散焦状态。电子束散焦时,束斑尺寸增大,激发的背散射电子在射出晶粒尺寸较小的样品表面时,在不同晶粒的不同晶面同时发生衍射,衍射花样会相互干扰,因而导致EBSD花样模糊、宽化、重叠,标定率变差。同时,较大的电子束束斑直径会降低EBSD空间分辨率,因而难以准确反映晶粒取向的细微变化。When EBSD is used to analyze a large area of a sample at low magnification,it is often found that the hit rate is low in the edge region.In order to explore the reasons for this phenomenon,the same acquisition area was selected at 100 magnification and moved to different positions for EBSD data acquisition in this research.The results show that the hit rates vary greatly in different areas when the test parameters remain unchanged.Even the orientation of the same grain is different when it is collected at different locations.The analysis finds that the main reason is the focused state of the electron beam.At low magnification,the electron beam is in focus at the center and out of focus at the edge of the same view.The defocused electron beam will increase the size of the beam spot.As a result,the excited backscattered electrons will encounter many disordered crystal faces when they emit on the surface of the sample with a smaller grain size.Therefore,it can not diffract well,resulting in blurs,widening,overlaps of EBSD pattern,and deterioration of the hit rate.Meanwhile,the larger spot size will reduce the spatial resolution of EBSD,so it is difficult to accurately represent the subtle changes of grain orientation.

关 键 词：大面积EBSD测试 标定率 散焦电子束 

分 类 号：TB331[一般工业技术—材料科学与工程] TG333[金属学及工艺—金属压力加工]