Penetrative Internal Oxidation from Alloy 690 Surfaces and Stress Corrosion Crack Walls during Exposure to PWR Primary Water
Penetrative Internal Oxidation from Alloy 690 Surfaces and Stress Corrosion Crack Walls during Exposure to PWR Primary Water
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DOI：
10.1007/978-3-319-48760-1_19
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发表时间：
2011
期刊：
影响因子：
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通讯作者：
M. Olszta;D. Schreiber;L. Thomas;S. Bruemmer
中科院分区：
文献类型：
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作者：
M. Olszta;D. Schreiber;L. Thomas;S. Bruemmer
采用分析电子显微镜和三维原子探针层析成像（ATP）技术对高温模拟压水堆一回路水环境中Ni-30%Cr合金690材料的表面和近表面氧化进行了研究。氧化纳米结构的特点是在应力腐蚀裂纹生长试验后的裂纹壁和抛光表面的无应力试样相同的合金。发现裂纹壁和表面的局部氧化为从水界面延伸到合金690基质中的连续细丝（通常直径<10 nm），达到约500 nm的深度。这些细丝由离散的，板状Cr2 O3颗粒周围分布的纳米晶体，岩盐（Ni-Cr-Fe）氧化物。发现含氧化物的细丝深度随暴露时间增加，并且在较长时间下，细丝在表面变得非常致密，仅留下孤立的金属岛。在未变形的材料中，单个位错被氧化，而在严重变形的材料中，氧化路径似乎是沿着更复杂的位错亚结构。本文将突出使用高分辨率扫描和透射电子显微镜与APT相结合，以更好地阐明的微观结构和微观化学的阴极氧化。
Analytical electron microscopy and three-dimensional atom probe tomography (ATP) examinations of surface and near-surface oxidation have been performed on Ni-30%Cr alloy 690 materials after exposure to high-temperature, simulated PWR primary water. The oxidation nanostructures have been characterized at crack walls after stress-corrosion crack growth tests and at polished surfaces of unstressed specimens for the same alloys. Localized oxidation was discovered for both crack walls and surfaces as continuous filaments (typically <10 nm in diameter) extending from the water interface into the alloy 690 matrix reaching depths of ~500 nm. These filaments consisted of discrete, plate-shaped Cr2O3particles surrounded by a distribution of nanocrystalline, rock-salt (Ni-Cr-Fe) oxide. The oxide-containing filament depth was found to increase with exposure time and, at longer times, the filaments became very dense at the surface leaving only isolated islands of metal. Individual dislocations were oxidized in non-deformed materials, while the oxidation path appeared to be along more complex dislocation substructures in heavily deformed materials. This paper will highlight the use of high resolution scanning and transmission electron microscopy in combination with APT to better elucidate the microstructure and microchemistry of the filamentary oxidation.