Water Vapour Embrittlement and Hydrogen Bubble Formation in Al–Zn–Mg Alloys

Alani, R.; Swann, P. R.

doi:10.1179/bcj.1977.12.2.80

Cited by 39 publications

(11 citation statements)

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“…Cracks in the passive layer further increase the reactivity by exposing bare metal to water. Several authors confirmed the blistering of the surface layer due to extensive reaction of aluminium with bulk water or condensate. Scamans and Rehal as well as Alani and Swann report that blistering occurred preferentially at magnesium‐rich grain boundary precipitates.…”

Section: Passive Layer On Aluminium Exposed To Water or Water Vapourmentioning

confidence: 89%

Evolution of surface characteristics of two industrial 7xxx aluminium alloys exposed to humidity at moderate temperature

Schwarzenböck

Hack

Kolb

et al. 2019

Surface & Interface Analysis

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This study analyses the evolution of surface characteristics of two industrial high‐strength 7xxx aluminium alloys with a focus on alloy composition and environmental parameters. Based on storage and transport conditions of as‐machined products, the effect of humidity—as liquid and vapour phase—on the natural oxide layer has been studied. The evolution of the natural oxide layer has been analysed by scanning electron microscopy and X‐ray photoelectron spectroscopy. The growth behaviour of the surface layer is dominated by environmental conditions, while microgalvanic activity depends mainly on the alloys' chemical composition and differs significantly for tested alloys. Scanning transmission electron microscopy images demonstrated that the long‐term exposure at moderate temperatures affects the microstructure near the surface, which differs for the analysed alloy compositions. An anomalous precipitation of zinc‐rich particles at the surface and along the precipitate‐free zone is observed for the alloy with higher Zn/Mg ratio and lower Cu content.

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Section: Passive Layer On Aluminium Exposed To Water or Water Vapourmentioning

confidence: 89%

Evolution of surface characteristics of two industrial 7xxx aluminium alloys exposed to humidity at moderate temperature

Schwarzenböck

Hack

Kolb

et al. 2019

Surface & Interface Analysis

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“…Stable hydrogen in the material is considered to come from the dissolution of physisorpt H 2 O, hydrides, and molecular hydrogen that exists within cavities. 6) Because no hydride was identified by the XRD analysis of the charged specimens, and no hydrogen desorption peaks were observed from the specimen immersed in water for the same duration as the electrochemical charging, the high-temperature peak was considered to correspond to molecular hydrogen that exists within cavities, not to hydrides or dissolution products from H 2 O. Figure 3 shows scanning electron microscopy (SEM) images of a specimen surface after charging under conditions of the immune and passive regions.…”

Section: Existing State Of Hydrogen Corresponding To Thementioning

confidence: 99%

“…[1][2][3][4][5][6][7][8] Furthermore, with the recent commercialization of fuel cells, it has become important to determine the effects of a high amount of absorbed hydrogen on the properties of aluminum because the chances of such materials being utilized in a hydrogen atmosphere are on the increase. Ohnishi 9) and Itoh and Kanno 10) summarized the existing states of hydrogen in aluminum; for example those are trapped to crystallographic imperfections like the interface of second phase, defects such as dislocations, solid solutions, or gaseous states within cavities.…”

Section: Introductionmentioning

confidence: 99%

Existing State of Hydrogen in Electrochemically Charged Commercial-Purity Aluminum and Its Effects on Tensile Properties

et al. 2011

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Hydrogen was introduced in commercial-purity (99%) aluminum by electrochemical charging to study the existing state of hydrogen and its effects on the mechanical properties of aluminum. Electrochemical charging was conducted in an aqueous H 2 SO 4 solution with 0.1% NH 4 SCN as a hydrogen recombination poison. The potential and pH during the charging were determined from the immune, passive, and corrosive regions in the Pourbaix diagram to determine the optimum conditions for the charging. The maximum amount of hydrogen absorbed was obtained in the immune region. The amount of hydrogen and its existing state were examined using hydrogen desorption curves, which were obtained by thermal desorption spectroscopy. The curves showed distinctive peaks corresponding to trapping sites of hydrogen in the material. One of the peaks was observed at approximately 100 C, and it corresponds to vacancies and dislocations in the material; another peak was observed at approximately 400 C and it corresponds to molecular hydrogen in blisters. It was presumed that charged hydrogen diffuses into the bulk of the material to form hydrogen-vacancy pairs, and then these pairs cluster to form blisters. The fracture strain of charged aluminum in the immune region decreased with decreasing strain rate, showing an inverse dependence on the fracture strain of the uncharged material. This phenomenon was considered to be caused by hydrogen transport by dislocations through the interaction between hydrogen and dislocations. The phenomenon was further confirmed by the observation of hydrogen release during tensile deformation, where the amount of hydrogen was high in the strain rate range where the interaction between dislocations and hydrogen was prominent.

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“…L'effet est particulièrement frappant dans les alliages à durcissement structural de la famille 7XXX (Al-ZnMg bas Cu). De nombreux auteurs [13][14][15][16][17] ont rapporté la formation de bulles d'hydrogène, à l'interface précipité intergranulaire/matrice après corrosion généralisée lente de la surface ou après piqûration des joints de grains. L'interprétation est la suivante : l'hydrogène, produit par les réactions cathodiques de surface, pénètre préférentiellement aux joints (surtout s'ils comportent des précipités riches en Mg).…”

Section: Décohésion Et Lacunes Surabondantesunclassified

Lacunes surabondantes dans les systèmes métal-hydrogène et endommagement des joints de grains : simulations atomiques

Tanguy

Vamvakopoulos

2009

PlastOx 2007 - Mécanismes Et Mécanique Des Interactions Plasticité - Environnement

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Résumé. Ce travail porte sur la modélisation de la perte de cohésion des joints de grains dans Al par ségrégation massive d'hydrogène (H). Nous tentons de poser simplement ce problème dans le contexte très « multi-échelle » de l'endommagement par H de matériaux ductiles : les alliages métalliques cubiques à faces centrées. En se référant aux calculs ab initio de la littérature, il est montré que la ségrégation de H seul ne permet pas de rendre compte de la décohésion observée expérimentalement. Un ingrédient microscopique supplémentaire doit être considéré. Nous proposons de prendre en compte la formation de lacunes surabondantes au niveau des joints (reconstruction des joints induite par H). Pour tester cette hypothèse, des méthodes de simulation à l'échelle atomique sont développées : Monte Carlo, pour le problème des lacunes dans le joint, et Dynamique Moléculaire contrainte, pour la propagation de fissures.

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Water Vapour Embrittlement and Hydrogen Bubble Formation in Al–Zn–Mg Alloys

Cited by 39 publications

References 0 publications

Evolution of surface characteristics of two industrial 7xxx aluminium alloys exposed to humidity at moderate temperature

Evolution of surface characteristics of two industrial 7xxx aluminium alloys exposed to humidity at moderate temperature

Existing State of Hydrogen in Electrochemically Charged Commercial-Purity Aluminum and Its Effects on Tensile Properties

Lacunes surabondantes dans les systèmes métal-hydrogène et endommagement des joints de grains : simulations atomiques

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