Strain and geometric necessary dislocations (GNDs) have been mapped with nm-resolution around grain boundaries affected by stress corrosion cracking (SCC) or intergranular oxidation with the aim of clarifying which local conditions that trigger SCC initiation of Alloy 600 in primary water reactor (PWR) water environment. Regions studied included the cracked and uncracked portion of the same SCC-affected grain boundaries and a comparable grain boundary in the as-received condition. High-resolution "on-axis" Transmission Kikuchi Diffraction (TKD) was used to generate strain and GND density based on the cross-correlation image processing method to probe shifts of specific zone axis in the TKD patterns from all regions. All cracked boundaries analyzed had local GND densities higher than 1 × 1016 m-2. Similar grain boundaries, from as-received samples had GNDs of 5 × 1014 m-2, while an intermediate level was found in the oxidized but uncracked portion of the same GB. Results, together with a discussion on the advantages and limitations of the approach, will be presented.

中文翻译：

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使用局部 GND 密度来研究 SCC 引发

应变和几何必要位错 (GND) 已在受应力腐蚀开裂 (SCC) 或晶间氧化影响的晶界周围以 nm 分辨率绘制，目的是阐明哪些局部条件会触发一次水反应堆 (PWR) 中合金 600 的 SCC 引发) 水环境。研究的区域包括受 SCC 影响的相同晶界的裂纹和未裂纹部分，以及在原样条件下的可比晶界。高分辨率“同轴”透射菊池衍射 (TKD) 用于基于互相关图像处理方法生成应变和 GND 密度，以探测来自所有区域的 TKD 图案中特定区域轴的偏移。分析的所有裂纹边界的局部 GND 密度均高于 1 × 1016 m-2。相似的晶界，收到样品的 GND 为 5 × 1014 m-2，而在同一 GB 的氧化但未开裂的部分中发现了中间水平。将介绍结果以及对该方法的优点和局限性的讨论。