Abstract The characterization of precipitates in bulk materials by Electron Backscatter Diffraction becomes challenging when the precipitate size falls below 200 nm. This is due to the drastic decrease of diffracted intensity with decreasing precipitate size and the rapidly growing signal generated by the surrounding matrix. A new technique is presented and allows determination of the structure and orientation of precipitates far below 100 nm directly in bulk samples in the Scanning Electron Microscope, normally requiring thin lamella extraction and Transmission Electron Microscopy analysis. The technique relies on the selective chemical etching of the matrix material of a sample, combined with the large tilt characteristic of the EBSD technique. As a result of the selective etching, precipitates protrude from the surface and emit what turns out to be a transmission diffraction signal instead of a backscatter diffraction signal, even though the sample remains massive. With this technique successful analysis of precipitates down to 30 nm was performed in a bulk Cu/Cr sample produced by Laser Powder Bed Fusion Additive Manufacturing with standard EBSD hardware. A Monte Carlo simulation confirms that the intensity of the transmission signal collected from a nanometer-sized precipitate protruding from the surface is much higher than the intensity of the backscatter signal collected from the same precipitate embedded right underneath the surface of a flat EBSD sample. Transmission signals emitted by bulk samples are a great opportunity to study features whose size are below the resolution limit of EBSD, like nanometer-sized precipitates, while keeping the possibility of exploring large areas and without the need to produce a thin lamella.

中文翻译：

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通过扫描电子显微镜中大块样品发射的透射衍射信号确定基质材料中纳米级沉淀物的结构和取向

摘要 当沉淀物尺寸低于 200 nm 时，通过电子背散射衍射表征块状材料中的沉淀物变得具有挑战性。这是由于衍射强度随着沉淀物尺寸的减小而急剧下降以及周围基质产生的快速增长的信号。提出了一种新技术，可以在扫描电子显微镜中直接在散装样品中确定远低于 100 nm 的沉淀物的结构和取向，通常需要薄层提取和透射电子显微镜分析。该技术依赖于样品基质材料的选择性化学蚀刻，结合 EBSD 技术的大倾斜特性。由于选择性蚀刻，沉淀物从表面突出并发射出透射衍射信号，而不是背向散射衍射信号，即使样品仍然很大。使用这种技术，在使用标准 EBSD 硬件的激光粉末床熔融增材制造生产的块状 Cu/Cr 样品中成功分析了低至 30 nm 的沉淀物。蒙特卡罗模拟证实，从表面突出的纳米级沉淀物收集的透射信号强度远高于从嵌入平坦 EBSD 样品表面下方的相同沉淀物收集的反向散射信号强度。大量样品发出的传输信号是研究尺寸低于 EBSD 分辨率极限的特征的绝佳机会，