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Interaction of primary precipitates in reduced -activation ferritic/martensitic steel F82H with hydrogen atoms: Atomistic calculation based on the density functional theory
To understand the interaction of hydrogen isotopes with VC and Cr23C6 precipitates, in reduced-activation ferritic/martensitic steel (F82H), we have performed first-principles calculations based on density functional theory. Energy calculations and electron density analysis were performed with a focus on the hydrogen retention by vacancies in precipitates. The H atoms in the C vacancy in the VC crystal are bound to the surrounding Cr atoms by relatively weak covalent forces and Coulombic attraction, and up to four H atoms are trapped. In the case of a Cr vacancy, H atoms are strongly covalently bonded to neighboring C atoms as well as to an interstitial H atom, capturing up to six H atoms. H atoms in vacancies in Cr23C6 have a weak bonding force with the Cr atom but a strong repulsive force with the C atom. As a result, H atom is not trapped in the Cr(4a) vacancy, and H atoms are trapped only at a distance from the C atom in the Cr(48H) and Cr(32f) vacancies. The Cr(8c) and C vacancies are relatively far from the C atoms and have higher hydrogen trapping energies. The Cr23C6 precipitate containing vacancies may be a dominant trapping site in the temperature range when H atoms immediately dissociate from vacancies. In addition, the VC precipitate may be the only trapping site for hydrogen isotopes at higher temperatures when Cr23C6 precipitates cannot trap them.
Interaction of primary precipitates in reduced -activation ferritic/martensitic steel F82H with hydrogen atoms: Atomistic calculation based on the density functional theory
To understand the interaction of hydrogen isotopes with VC and Cr23C6 precipitates, in reduced-activation ferritic/martensitic steel (F82H), we have performed first-principles calculations based on density functional theory. Energy calculations and electron density analysis were performed with a focus on the hydrogen retention by vacancies in precipitates. The H atoms in the C vacancy in the VC crystal are bound to the surrounding Cr atoms by relatively weak covalent forces and Coulombic attraction, and up to four H atoms are trapped. In the case of a Cr vacancy, H atoms are strongly covalently bonded to neighboring C atoms as well as to an interstitial H atom, capturing up to six H atoms. H atoms in vacancies in Cr23C6 have a weak bonding force with the Cr atom but a strong repulsive force with the C atom. As a result, H atom is not trapped in the Cr(4a) vacancy, and H atoms are trapped only at a distance from the C atom in the Cr(48H) and Cr(32f) vacancies. The Cr(8c) and C vacancies are relatively far from the C atoms and have higher hydrogen trapping energies. The Cr23C6 precipitate containing vacancies may be a dominant trapping site in the temperature range when H atoms immediately dissociate from vacancies. In addition, the VC precipitate may be the only trapping site for hydrogen isotopes at higher temperatures when Cr23C6 precipitates cannot trap them.
Interaction of primary precipitates in reduced -activation ferritic/martensitic steel F82H with hydrogen atoms: Atomistic calculation based on the density functional theory
Hirotomo Iwakiri (author) / Yoshiyuki Watanabe (author) / Koichi Sato (author) / Daiji Kato (author)
2022
Article (Journal)
Electronic Resource
Unknown
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