A new method for locating Kikuchi bands in electron backscatter diffraction patterns

Abstract

Electron backscatter diffraction (EBSD) device can provide crystal structure, orientation, and phase content data through analysis of EBSD patterns. The reliability and precision of these data depend on the quality of the band position and zone axes data. This study introduces a new image processing method that can accurately provide the location of Kikuchi bands and poles. In this method, pattern rotation and gray gradient calculation are employed after for the initial detection of Kikuchi lines. Hough transform and Gaussian function are used for the final definition of bands position. Based on the position of Kikuchi bands, the indices of lattice planes and zone axes can be obtained precisely and easily. Angles between zone axes are calculated using locating results. The maximum error for a single-crystal silicon sample is only 8.07%, illustrating the accuracy of this new method. K E Y W O R D S edge detection, electron backscatter diffraction, image processing, Kikuchi bands

Local Kikuchi band detection in electron backscatter diffraction patterns for enhanced pattern indexing

“…Figure 3A showed the EBSD mapping of the stainless‐steel sample mentioned in Section 2. Here, the method, termed as AGGBD 16 in our previous research, was first used to calculate CL, because of its high efficiency and accurate detection in high‐quality patterns. For instance, an indexed point with CL = 2 was chosen (Figure 3A).…”

“…Furthermore, the previously reported algorithms 15,16 were also modified to automatically search for partially clear bands in low‐quality patterns. According to the pattern resolution (1344 × 1024), the statistic height for calculating average grey gradient was set to 400 pixels, which makes sure that about one‐third of the whole height of acquired patterns can be used to analyse.…”

“…In addition, it might not be useful when the quality of all neighbouring patterns was the same. Previous research by our group successfully located the bands of silicon single crystal patterns by rotating the pattern and calculating the average grey gradient at each angle using a method called average grey gradient band detection (AGGBD) 15,16 . However, this method was not effective for patterns with low‐intensity bands and partially missing bands.…”

Method for acquiring accurate coordinates of the source point in electron backscatter diffraction

“…EBSD can be used to obtain different types of information, such as the crystal structure, grain size, phase content and elastic strain measurements 1–3 by indexing the diffraction patterns collected, 4 including locating the Kikuchi bands and zone axes and calculating the interplanar angles 5 . In a previous study, we proposed a method for locating Kikuchi bands and zone axes that was called the grey gradient calculation method 6 . The principle of this method is depicted in Figure 1.…”

Method of Crystal Structure Identification by Using Kikuchi Diffraction Patterns

“…电子背散射衍射(EBSD)作为一种相对较新的 显微结构分析手段，可以在较大范围内提供材料的 取向、织构、相鉴定及含量分布等晶体学统计性信 息 [1][2][3][4] ，为无机材料制备工艺的改善、微结构调控及 性能优化提供了可靠的科学依据。Fang 等 [5] 通过 EBSD 技术对梯度纳米(GNG)金属铜进行表征， 为解释其拉伸变形的机理提供了重要显微结构证据。 EBSD 还是研究涂层内部残余应力分布的最佳显微 结构分析手段，为研究热障涂层的服役失效行为提 供了重要支撑。EBSD 提供的所有晶体学信息都依 赖对菊池衍射花样的分析 [6] ，菊池花样直观反映材 料内部微观结构，其中，菊池带对应不同指数的晶 面，菊池带的交点即菊池极代表晶带轴 [4] [7] 尝试利用对称性进行相鉴定，但 因为晶面间距计算误差较大，只能依靠肉眼在菊池 花样中识别对称轴，容易误判。通过菊池带宽度计 算晶面间距的误差通常较大(5%~20%) [7][8] ，这是 用菊池花样进行对称性分析的最大难点。我们前期 工作对晶面间距进行了准确测量，平均相对误差为 2.6% [9] ，为准确识别对称轴奠定了基础，还可区分 非对称轴。对 Si 单晶菊池花样的分析发现了类似三 次轴的非对称轴，计算晶面间距发现，菊池带并不 属于同一晶面族，不满足三次轴的条件，这是肉眼 识别很容易误判的。晶面夹角可通过三维空间矢量 计算获得 [10]…”