Electron tomography of unirradiated and irradiated nuclear graphite

Arregui-Mena, José David; Cullen, David A.; Worth, Robert N.; Venkatakrishnan, Singanallur; Jordan, Matthew S.L.; Ward, Michael B.; Parish, Chad M.; Gallego, Nidia; Katoh, Yutai; Edmondson, Philip D.; Tzelepi, Athanasia

doi:10.1016/j.jnucmat.2020.152649

Cited by 13 publications

(7 citation statements)

References 35 publications

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“…2021 [45] Electron tomography was adapted to characterize as-received and neutron-irradiated tips of nanocracks in IG-110. This article shows the 3D structure of the nanocracks found in graphite via 3D reconstructions obtained from different projections of images taken in STEM mode.…”

Section: Liu and Chernsmentioning

confidence: 99%

Report on initial development of a database of nuclear graphite characteristics based on microstructural characterization

Arregui-Mena,

Gallego

2023

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Section: Liu and Chernsmentioning

confidence: 99%

Report on initial development of a database of nuclear graphite characteristics based on microstructural characterization

Arregui-Mena,

Gallego

2023

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“…For example, the microscale high-aspect ratio intergranular cracks promote internal stress concentration, yet nanoscale Mrozowski cracks with similar aspect ratios help densification during irradiation [13]. The conundrum is that defects in polycrystalline graphite are helpful in accommodating deformation during external loading and radiation but also contribute to oxidation and damage at higher doses [14]. The larger pores influence mechanical properties, while smaller pores control irradiation-induced dimensional changes.…”

Section: Introductionmentioning

confidence: 99%

Real-Time Observation of Nanoscale Kink Band Mediated Plasticity in Ion-Irradiated Graphite: An In Situ TEM Study

Thomas,

Schoell,

Al-Mamun

et al. 2024

Materials

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Graphite IG-110 is a synthetic polycrystalline material used as a neutron moderator in reactors. Graphite is inherently brittle and is known to exhibit a further increase in brittleness due to radiation damage at room temperature. To understand the irradiation effects on pre-existing defects and their overall influence on external load, micropillar compression tests were performed using in situ nanoindentation in the Transmission Electron Microscopy (TEM) for both pristine and ion-irradiated samples. While pristine specimens showed brittle and subsequent catastrophic failure, the 2.8 MeV Au2+ ion (fluence of 4.378 × 1014 cm−2) irradiated specimens sustained extensive plasticity at room temperature without failure. In situ TEM characterization showed nucleation of nanoscale kink band structures at numerous sites, where the localized plasticity appeared to close the defects and cracks while allowing large average strain. We propose that compressive mechanical stress due to dimensional change during ion irradiation transforms buckled basal layers in graphite into kink bands. The externally applied load during the micropillar tests proliferates the nucleation and motion of kink bands to accommodate the large plastic strain. The inherent non-uniformity of graphite microstructure promotes such strain localization, making kink bands the predominant mechanism behind unprecedented toughness in an otherwise brittle material.

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“…IG-110 is a fine-grained isotropic graphite which exhibits high thermal strength and durability, making it very suitable for use in the nuclear industry. However, it was reported that IG-110 oxidizes faster with deeper oxidant penetration which is related to the needle-shaped filler structure of the petroleum coke as the source [18]. The characteristics of nuclear graphite are very important to note, such as its pores and cracks because it can accommodate unfavorable operational conditions [19].…”

Section: Introductionmentioning

confidence: 99%

Investigation On Oxidation Behavior of Nuclear Graphite IG-110 At Elevated Temperature

Herlina,

Rivai,

Rivai

2023

Jurnal Sains Materi Indonesia

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IG-110 is one of nuclear graphite types for high temperature gas cooled reactor. One of the issues of the graphite in the reactor system is the interaction with air or/and water which can reduce the integrity of the material. In this study, the sample of IG-110 has been tested at high temperature in an air environment. The oxidation test was done using a magnetic suspension balance to analyze the changes in weight with direct monitoring. The test was carried out at a temperature of 630°C. Morphological and microstructural analysis were observed and tested using scanning electron microscope (SEM) and X-ray diffractometer (XRD). The oxidation rate of the sample was relatively low. Rougher sheets shape, larger pores, and slight cracks were observed for the tested sample which indicate the traces of oxidation of the samples with no any critical damage occurred in the sample. Lattice parameters, density, crystal size, and d-space of the sample after oxidation test slightly change, which show the reversible characteristic of the sample from the temperature viewpoint.

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Electron tomography of unirradiated and irradiated nuclear graphite

Cited by 13 publications

References 35 publications

Report on initial development of a database of nuclear graphite characteristics based on microstructural characterization

Report on initial development of a database of nuclear graphite characteristics based on microstructural characterization

Real-Time Observation of Nanoscale Kink Band Mediated Plasticity in Ion-Irradiated Graphite: An In Situ TEM Study

Investigation On Oxidation Behavior of Nuclear Graphite IG-110 At Elevated Temperature

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