Hydrogen-Promoted Grain Boundary Embrittlement and Vacancy Activity in Metals: Insights from Ab Initio Total Energy Calculatons
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- Geng Wen-Tong
- Department of Physics and Astronomy, Northwestern University National Institute for Materials Science
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- Freeman Arthur J.
- Department of Physics and Astronomy, Northwestern University
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- Olson Gregory B.
- Department of Materials Science and Engineering, Northwestern University
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- Tateyama Yoshitaka
- National Institute for Materials Science
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- Ohno Takahisa
- National Institute for Materials Science
書誌事項
- タイトル別名
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- Hydrogen-Promoted Grain Boundary Embrittlement and Vacancy Activity in Metals: Insights from <I>Ab Initio</I> Total Energy Calculatons
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The rapid diffusion of H in metals permits an easy segregation to the grain boundary and an easy trapping to the vacancy. H-induced intergranular embrittlement in metals such as Fe and Ni is generally a result of coalition of segregated H and other embrittling impurities at the grain boundary. Ab initio total energy calculations based on the density functional theory have shown that H alone can also weaken the cohesion across the grain boundary. The stronger binding of H with a free surface than with a grain boundary, which results in grain boundary embrittlement according to the Rice–Wang theory, can be ascribed to its monovalency. New tensile experiments point to a H-enhanced vacancy contribution to the increased susceptibility of steel to H embrittlement. Ab initio density functional calculations on the energetics of interstitial H, vacancy, and H-monovacancy complexes (VacHn) in bcc Fe have shown that the predominant complex under ambient condition of H pressure is VacH2, not VacH6 as previously suggested by effective-medium theory calculations. The linear structure of VacH2 clusters, a consequence of repulsion between negatively charged H atoms, facilitates the formation of linear and tabular vacancy clusters and such anisotropic clusters may lead to void or crack nucleation on the cleavage planes. On the other hand, the H-induced increase of vacancy cluster formation energy is a support of the experimentally observed enhancement of dislocation mobility in the presence of H, which, through the mechanism of H-enhanced localized plasticity, makes fracture easier.
収録刊行物
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- MATERIALS TRANSACTIONS
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MATERIALS TRANSACTIONS 46 (4), 756-760, 2005
公益社団法人 日本金属学会
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詳細情報 詳細情報について
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- CRID
- 1390001204249780224
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- NII論文ID
- 130004452762
- 10015520424
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- NII書誌ID
- AA1151294X
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- COI
- 1:CAS:528:DC%2BD2MXlt1yit7w%3D
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- ISSN
- 13475320
- 13459678
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- NDL書誌ID
- 7304316
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- 本文言語コード
- en
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- データソース種別
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- JaLC
- NDL
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