Hydrogen relaxation in α-iron

Dufresne, J.; Seeger, A.; Groh, P.; Moser, P.

doi:10.1002/pssa.2210360218

Cited by 41 publications

(10 citation statements)

References 19 publications

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“…From inspection of these results, it becomes apparent that, up to now, no SnoekRichter ± ± type relaxation has been observed as yet in H-charged a-Fe [196,201,204,207]. This is also true for a recent investigation, performed by Hirscher [210] on H-and deuterium (D)-charged, unirradiated and e À -irradiated a-Fe.…”

Section: Maes In Fehsupporting

confidence: 53%

“…This conclusion was further supported by the fact that charging with hydrogen, following plastic deformation of the crystal, produced complete suppression of the low-temperature relaxation in favour of an additional, strong relaxation at 180 K. On annealing within the temperature range 200 K < T a < 450 K, this 180 K peak was found to be reduced in strength and shifted to lower temperatures [202 to 205]. All these various reactions are most consistently explained within the following scheme: a) 10 to 30 K: so-called a-peak, resulting from thermally activated formation of double-kinks on non-screw dislocations [194,204,206,207].…”

Section: Maes In Fehmentioning

confidence: 99%

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A Review of the Magnetic Relaxation and Its Application to the Study of Atomic Defects in ?-Iron and Its Diluted Alloys

Blythe

Kronmüller²,

Seeger³

et al. 2000

phys. stat. sol. (a)

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This review presents a comprehensive survey on intensive studies performed during the last decades on point defect reactions on a-iron (a-Fe) and its diluted alloys. Our intention is to give an actual account of the knowledge accumulated on this subject, as it has been obtained predominantly by means of the magnetic after-effect (MAE) spectroscopy. After a concise introduction into the theoretical and experimental fundamentals of this technique, the main concern is focused on the presentation and detailed discussion of the MAE spectra arising ± ± after low-temperature electron (e À )-or neutron(n)-irradiation and subsequent annealing ± ± in: (i) high-purity a-Fe and a-Fe doped with (ii) substitutional solutes (like Ni, V, Al, Cu, Ti, Be, Si, Mn, . . .) or (iii) interstitial solutes (like O, H, C, N). During the course of systematic annealing treatments, these respective spectra undergo dramatic variations at specific temperatures thereby revealing in great detail the underlying intrinsic reactions of the radiation-induced defects, i.e., reorientation, migration, clustering, dissolution and finally annihilation. In alloyed Fe systems the corresponding reaction sequences are even multiplied due to additional interactions between defects and solute atoms. Most valuable information concerning formation-, dissociation-and binding enthalpies of small, mixed clusters (of the type C i V k , N i V k ; i; k ! 1) has been obtained in highpurity a-Fe base material which, after charging with C or N, had been e À -irradiated. Concerning the basic recovery mechanisms in a-Fe, two complementary results are obtained from the analysis of the various systems: (i) in high-purity and substitutionally alloyed a-Fe the recovery in Stage-III (200 K) is governed by a three-dimensionally migrating (H M I 0:56 eV) stable interstitial (dumbbell); (ii) following the formation and dissociation kinetics of small clusters (C 1 V k , N 1 V k ) in interstitially alloyed a-Fe the migration enthalpy of the monovacancy must hold the following relation H M N (0.76 eV) < H M C (0.84 eV) < H M V1 . These results are in clear agreement with the socalled two-interstitial model (2IM) in a-Fe ± a conclusion being further substantiated by a systematic comparison with the results obtained from nonrelaxational techniques, like i.e. positron annihilation (PA), which by their authors are preferentially interpreted in terms of the one-interstitial model (1IM).Die vorliegende Arbeit gibt einen umfassenden Ûberlick u È ber die wa È hrend der letzten Jahrzehnte durchgefu È hrten, eingehenden Untersuchungen der Punktfehler-Eigenschaften in a-Eisen (a-Fe) und verdu È nnten Fe-Legierungen. Demgema È û ist diese Zusammenfassung gedacht als ein dem gegenwa Èrtigen Kenntnisstand entsprechender Rechenschaftsbericht u È ber die auf diesem Gebiet, hauptsa È chlich mit Hilfe der magnetischen Nachwirkungs (MNW) ± ± Spektroskopie, gewonnenen, tiefreichenden Einsichten in diesen Problemkreis. Nach einer kurzen Einfu È hrung in die theoretischen und experimentellen Grundlagen di...

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Section: Maes In Fehsupporting

confidence: 53%

Section: Maes In Fehmentioning

confidence: 99%

A Review of the Magnetic Relaxation and Its Application to the Study of Atomic Defects in ?-Iron and Its Diluted Alloys

Blythe

Kronmüller²,

Seeger³

et al. 2000

phys. stat. sol. (a)

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“…Therefore, it is confirmed that there are some energy cusps in such dependence, which could be explained by a special atomic ordering, which causes a change in the grain-boundary energy. A perfect agreement is obtained between the data calculated in the present study and the experimental activation enthalpy for the bulk hydrogen diffusion [39,42]. The comparison of these data with those obtained for the system containing grain boundaries clearly shows that the activation enthalpy for diffusion of hydrogen in the vicinity of the grain boundary is always higher.…”

Section: Resultssupporting

confidence: 85%

Grain-Boundary Diffusion of Hydrogen Atoms in the $\alpha$-Iron

Teus¹,

Gavriljuk²

2016

Metallofiz. Noveishie Tekhnol.

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Grain boundary diffusion of hydrogen atoms in the -iron is analysed based on the theoretical modelling. By means of molecular-dynamics simulation of hydrogen-atoms' migration in selected special grain boundaries with different misorientation angles as well as in the bulk, it is demonstrated that the activation enthalpy of hydrogen migration in the grain boundary is higher than that in the bulk. Based on this result, a conclusion is made that grain boundaries in the iron are traps for hydrogen atoms and retard their migration. As supposed, an increase in the hydrogen grain-boundary diffusion, as observed in some experiments, is related to the hydrogen-caused intergranular cracking.За допомогою теоретичного моделювання було проаналізовано зерноме-жову дифузію атомів водню в -залізі. Молекулярно-динамічне моделю-вання міґрації атомів водню в обраних межах зерен з різними кутами дез-орієнтації, а також в об'ємі зерна, показало, що ентальпія активації міґ-рації атомів водню по межах зерен вища, ніж відповідне значення в об'ємі зерна. На підґрунті цих результатів зроблено висновок, що межі зерен у залізі є пастками для атомів водню і сповільнюють їх міґрацію. Зроблено припущення, що збільшення коефіцієнта зерномежової дифузії водню, яке спостерігалося в деяких експериментах, пов'язане з індукованим во-днем міжкристалітним розтріскуванням.Посредством теоретического моделирования исследована зернограничная диффузия атомов водорода в -железе. Молекулярно-динамическое моде-лирование миграции атомов водорода в выбранных границах зёрен с раз-ными углами разориентировки, а так же в объёме зерна, показало, что энтальпия активации миграции атомов водорода по границам зёрен вы-ше, чем соответствующее значение в объёме зерна. Основываясь на этих результатах, сделан вывод, что границы зёрен в железе являются ловуш-ками для атомов водорода и замедляют их миграцию. Сделано предполо-жение, что увеличение коэффициента зернограничной диффузии водоро-

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“…The data for the enthalpy of bulk hydrogen diffusion are in a perfect consistency with the experimental activation enthalpy obtained in [21,22], whereas the activation enthalpy for hydrogen diffusion along the grain boundaries is always higher in comparison with that of bulk diffusion.…”

Section: Modellingsupporting

confidence: 83%

Hydrogen Grain Boundary Segregation and Migration in the Alpha-Iron

Gavriljuk¹,

Teus²

2017

Metallofiz. Noveishie Tekhnol.

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Based on the difference in diffusion mechanisms of substitutional and interstitial atoms and using molecular dynamics simulation of hydrogen migration, it is shown that accelerated hydrogen flux in the polycrystalline iron observed during cathodic charging cannot originate from the enhanced hydrogen grain-boundary diffusion. A possible role of grain-boundary cracking is supposed.Key words: hydrogen diffusion, grain boundaries, molecular dynamics simulation.Ґрунтуючись на відмінностях механізмів дифузії атомів заміщення та втілення і використовуючи молекулярно-динамічні розрахунки міґрації атомів Гідроґену, показано, що прискорений потік водню в полікристалі-чному залізі, який спостерігається в процесі катодного наводнення, не може бути наслідком прискореної зерномежової дифузії водню. Розгляда-ється можлива роль зерномежового розтріскування.Ключові слова: дифузія водню, межі зерен, молекулярна динаміка.Основываясь на отличиях механизмов диффузии атомов замещения и внедрения и используя моделирование методом молекулярной динамики миграции водорода, показано, что ускоренный поток водорода в поликри-сталлическом железе, который наблюдается в процессе катодного наводо-раживания, не может быть следствием ускоренной зернограничной диф-фузии водорода. Рассмотрена возможная роль зернограничного растрес-кивания.

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Hydrogen relaxation in α-iron

Cited by 41 publications

References 19 publications

A Review of the Magnetic Relaxation and Its Application to the Study of Atomic Defects in ?-Iron and Its Diluted Alloys

A Review of the Magnetic Relaxation and Its Application to the Study of Atomic Defects in ?-Iron and Its Diluted Alloys

Grain-Boundary Diffusion of Hydrogen Atoms in the $\alpha$-Iron

Hydrogen Grain Boundary Segregation and Migration in the Alpha-Iron

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