Focused ion beam (FIB) milling has evolved to be one of the most important Transmission Electron Microscope (TEM) site specific sample preparation techniques. However, this technique still poses challenges, such as the structural damage and potential curtaining issues often observed for thin TEM lamella. These artefacts can negatively affect the TEM analysis results. In particular, structures such as internal cracks and pores in FIB prepared TEM samples can often be damaged during sample preparation. This is commonly regarded as an unavoidable problem, even though microstructurally intact thin lamellae TEM samples are widely needed for the investigation of crack tips or pore morphologies in many different materials. This presents a strong driver for the development of innovative methods to overcome damage and curtaining issues during FIB sample preparation. Here we report on a new methodology developed to protect internal cracks and pores from ion beam damage. Our proposed method also mitigates curtaining issues, which often make TEM analysis more difficult. This method uses the FIB to sputter and redeposit material onto the edges of any cracks or pores in order to fill these features in-situ prior to lamella thinning. Case studies showcasing this method are presented, demonstrating the approach on a modular pure iron sample and on a porous laser treated Al/B4C composite sample. Our proposed 'filling' method has demonstrated a two key benefits; it preserves the integrity of the edges of any cracks and pores and it reducing curtaining. The results also demonstrate that this technique can be an alternative to conventional Gas Injection System (GIS) deposition for protecting the external top surface.

中文翻译：

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使用 FIB 保护内部裂纹/孔免受离子束损伤并减少 TEM 样品制备的帷幕的原位方法

聚焦离子束 (FIB) 铣削已发展成为最重要的透射电子显微镜 (TEM) 现场特定样品制备技术之一。然而，这种技术仍然存在挑战，例如经常观察到薄 TEM 薄片的结构损坏和潜在的窗帘问题。这些伪影会对 TEM 分析结果产生负面影响。特别是，FIB 制备的 TEM 样品中的内部裂纹和孔隙等结构通常会在样品制备过程中被损坏。这通常被认为是一个不可避免的问题，即使在许多不同材料中研究裂纹尖端或孔隙形态时，广泛需要微观结构完整的薄层状 TEM 样品。这为开发创新方法以克服 FIB 样品制备过程中的损坏和遮挡问题提供了强大的驱动力。在这里，我们报告了一种为保护内部裂纹和孔隙免受离子束损伤而开发的新方法。我们提出的方法还减轻了窗帘问题，这通常会使 TEM 分析更加困难。该方法使用 FIB 将材料溅射并重新沉积到任何裂缝或孔的边缘，以便在薄片减薄之前原位填充这些特征。展示了这种方法的案例研究，展示了模块化纯铁样品和多孔激光处理的 Al/B4C 复合样品的方法。我们提出的“填充”方法已经证明了两个关键的好处；它保留了任何裂缝和孔隙边缘的完整性，并减少了窗帘。