An atom probe tomography study of internal oxidation processes in Alloy 600

Langelier, Brian; Persaud, S.Y.; Newman, R. C.; Botton, Gianluigi A.

doi:10.1016/j.actamat.2016.02.054

Cited by 68 publications

(26 citation statements)

References 55 publications

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“…These Nirich regions are free of oxygen, suggesting that Ni in these regions exists in its metallic phase. The Nirich features were also reported by Langalier et al [32] and Bertali et al [33] in the study of internal oxidation of Alloy 600 in hydrogenated steam at 480ºC. The authors attributed the formation of Nirich features to the expulsion of metallic Ni during the selective oxidation more reactive elements (such as Cr and/or Fe) under the low oxidation potential environment.…”

supporting

confidence: 71%

Observation of internal oxidation in a 20% cold-worked Fe-17Cr-12Ni stainless steel through high-resolution characterization

et al. 2019

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It is often assumed that internal oxidation cannot occur at temperatures below 400ºC. However, in the present work, internal oxidation was observed in a 20% cold-worked Fe-17Cr-12Ni stainless steel (SS) after exposure to simulated primary water of a pressurized water reactor at 340ºC and not in a similarly tested sample without prior cold-work. The formation of discrete Cr-oxide precipitates and the role of cold-work are discussed. The internal oxidation model is also proposed as a plausible stress corrosion cracking mechanism of Fe-17Cr-12Ni SS at that temperature.

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supporting

confidence: 71%

Observation of internal oxidation in a 20% cold-worked Fe-17Cr-12Ni stainless steel through high-resolution characterization

et al. 2019

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“…to the work conducted in the literature [3,5,11,16,23,40], the selective oxidation of Cr could lead to the separation of Cr oxide precipitates and metallic Fe and Ni, which will inevitably introduce vacancies or pores in the incoherent interfaces of these different phases. Selective oxidation-induced separation of different phases was not only observed by EDX [24] and EELS [3], but also observed via atom probe tomography (APT) [41] and atomic-resolution TEM [42]. Consequently, the nano-pores induced by the selective oxidation might explain why the porosity of the intergranular oxide was higher than the outer surface oxide.…”

Section: The Effect Of Cold-worked Surface On the Crack Initiationmentioning

confidence: 95%

Characterization of the crack initiation and propagation in Alloy 600 with a cold-worked surface

et al. 2019

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The crack initiation on a cold-worked surface of Alloy 600, exposed to simulated pressurized water reactor primary water, was mechanistically studied through high-resolution characterization. Mechanical polishing introduced a thin recrystallization layer on the specimen surface, which lead to the crack initiation along highlydeformed recrystallization grain boundaries after preferential oxidation. Intergranular crack propagation occurred once the initiation cracks met the matrix grain boundaries under the external loading and the residual stress introduced by the prior 20% cold working. The controlling mechanism of SCC crack propagation was believed to be an intergranular selective oxidation mechanism.

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“…Furthermore, a banded grain boundary structure, which appeared to protrude from the surface forming ridges on the specimen surface, was also visible. The surface nodules forming on Alloy 600 in this specific environment and temperature have been already extensively characterized by AEM and atom probe tomography and reported to be mainly composed of pure metallic Ni [35,[45][46][47]. They have been extensively investigated and are believed to form as a result of internal oxidation and solvent diffusion to the surface [46,47].…”

Section: Sem Characterisation Of the Oxidized Surfacementioning

confidence: 99%

The intergranular oxidation susceptibility of thermally–treated Alloy 600

2017

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The oxidation behaviour of thermally-treated Alloy 600 was studied using hydrogenated steam at 480°C, environment known to simulate pressurized water reactors conditions, and subsequently analyzed using analytical electron microscopy. Focused Ion Beam and analytical transmission electron microscopy provided definitive evidence of localized intergranular carbides decomposition and the formation of an intergranular Cr-rich oxide embryo. These results are discussed in this paper in terms of early stages of preferential intergranular oxidation and grain boundary migration, carbide decomposition, GB pinning and the effect of local carbon enrichments in the matrix.

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An atom probe tomography study of internal oxidation processes in Alloy 600

Cited by 68 publications

References 55 publications

Observation of internal oxidation in a 20% cold-worked Fe-17Cr-12Ni stainless steel through high-resolution characterization

Observation of internal oxidation in a 20% cold-worked Fe-17Cr-12Ni stainless steel through high-resolution characterization

Characterization of the crack initiation and propagation in Alloy 600 with a cold-worked surface

The intergranular oxidation susceptibility of thermally–treated Alloy 600

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