Sequential 2D sectioning and imaging using a dual-beam focused ion beam and scanning electron microscope has been used to characterise the interconnectivity of cracks in oxide films on Zircaloy-4. Evidence of cracks perpendicular to the metal/oxide interface have been observed in multiple oxides of different thicknesses. Such vertical features are considered critical in the provision of a percolation path between the environment and innermost band of lateral cracks (closest to oxide/environment interface), in between the lateral bands of cracks and between the final band of lateral cracks and the metal/oxide interface. Given the limited occurrence of cracks perpendicular to the metal/oxide interface, localised tensile surface strains have been considered as a potential source of initiation of these cracks.

使用双束聚焦离子束和扫描电子显微镜的连续2D切片和成像已用于表征Zircaloy-4上氧化膜中裂纹的互连性。在多种不同厚度的氧化物中都观察到了垂直于金属/氧化物界面的裂纹。在环境和横向裂纹的最内部带（最靠近氧化物/环境界面）之间，裂纹的横向带之间以及横向裂纹的最终带与金属/金属之间提供渗流路径时，认为此类垂直特征至关重要氧化物界面。鉴于垂直于金属/氧化物界面的裂纹的发生有限，因此局部拉伸表面应变已被视为引发这些裂纹的潜在来源。