Zhong Xiang Li, Haigh Sarah J, Zhou Xiaorong, Withers Philip J
Department of Materials, University of Manchester, Oxford Road, Manchester, M13 9PL, UK; Henry Royce Institute, Department of Materials, University of Manchester, Oxford Road, Manchester, M13 9PL, UK.
Department of Materials, University of Manchester, Oxford Road, Manchester, M13 9PL, UK.
Ultramicroscopy. 2020 Dec;219:113135. doi: 10.1016/j.ultramic.2020.113135. Epub 2020 Oct 10.
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/BC 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.
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）特定部位样品制备技术之一。然而，该技术仍然存在挑战，例如在薄TEM薄片中经常观察到的结构损伤和潜在的拖尾问题。这些伪像会对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在样品制备过程中常常会受到损坏。即使在许多不同材料中研究裂纹尖端或孔隙形态广泛需要微观结构完整的薄薄片TEM样品，这通常也被视为一个不可避免的问题。这为开发创新方法以克服FIB样品制备过程中的损伤和拖尾问题提供了强大的动力。在此，我们报告一种新开发的方法，用于保护内部裂纹和孔隙免受离子束损伤。我们提出的方法还减轻了拖尾问题，而拖尾问题常常使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纹或孔隙的边缘，以便在薄片减薄之前原位填充这些特征。展示了该方法的案例研究，在模块化纯铁样品和多孔激光处理的Al/BC复合样品上演示了该方法。我们提出的“填充”方法已证明有两个关键优点；它保留了任何裂纹和孔隙边缘的完整性并减少了拖尾。结果还表明，该技术可以替代传统的气体注入系统（GIS）沉积来保护外部顶面。
