Готові списки джерел за темами / Grain boundary oxidation

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Добірка наукової літератури з теми "Grain boundary oxidation"

Автор: Grafiati

Опубліковано: 3 червня 2022

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Статті в журналах з теми "Grain boundary oxidation"

Philibert, Jean. "Grain Boundary Diffusion and Oxidation Processes." Defect and Diffusion Forum 156 (February 1998): 1–8. http://dx.doi.org/10.4028/www.scientific.net/ddf.156.1.

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Philibert, J. "Grain boundary diffusion and oxidation processes." Solid State Ionics 117, no. 1-2 (February 1, 1999): 7–11. http://dx.doi.org/10.1016/s0167-2738(98)00242-2.

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Liu, Ya, Sai Liu, Xuping Su, Haoping Peng, Jianhua Wang, and Hao Tu. "Calculation of Selective Oxidation in Grain and Grain Boundary." Journal of Phase Equilibria and Diffusion 34, no. 2 (January 12, 2013): 82–88. http://dx.doi.org/10.1007/s11669-012-0184-z.

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Krupp, Ulrich, V. B. Trindade, Peter Schmidt, Hans Jürgen Christ, U. Buschmann, and W. Wiechert. "The Effect of Grain-Boundary Diffusion on the Oxidation of Low-Chromium Steels." Defect and Diffusion Forum 237-240 (April 2005): 946–51. http://dx.doi.org/10.4028/www.scientific.net/ddf.237-240.946.

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Even though the oxidation behavior of steels is generally considered as to be widely understood, a closer look reveals some open questions, e.g. regarding the influence of the substrate grain size on the overall oxidation kinetics. At temperatures below 570°C the main constituent of the oxide scale formed on top of low alloy steels is magnetite. As shown by gold marker experiments it grows outward and inward at the same time, the latter exhibiting a gradual transition to the more stable spinel compound FeCr2O4. As indicated by intergranular-oxidation attack below the superficial scale, inward oxide growth seems to be driven by oxygen transport along the grain boundaries serving as fast diffusion paths. This is supported by thermogravimetric oxidation tests in air on low-Cr steels with varying grain size: The smaller the grains the higher the oxidation rate. Recently, a numerical model for the diffusive transport processes based on the finite-difference approach has been developed, which distinguishes between fast grain-boundary diffusion and bulk diffusion. Qualitatively, it is capable to predict the relationship between substrate grain size and inward oxide growth kinetics. Together with the thermodynamic tool ChemApp and in combination with a data set for the Fe-Cr-O system the mechanism-based simulation of the overall oxidation process of low-Cr steels is possible.

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Park, Kee Hyun, and Paul Withey. "Formation of Secondary Phases in the Boundary between Surface Defect Grains and Matrix in Third Generation Nickel-Based Single Crystal Superalloy Turbine Blades." Materials Science Forum 941 (December 2018): 766–71. http://dx.doi.org/10.4028/www.scientific.net/msf.941.766.

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Ni-based single crystal superalloy turbine blades have excellent mechanical strength and resistance to corrosion and oxidation due to a uniformly distributed gamma prime phase in a gamma matrix. However, defect grains have been often found on the surface of turbine blades after manufacturing, which can be potential sites of crack initiation. In this study, several different types of surface defect grains formed in third generation Ni-based single crystal turbine blades, such as stray grains, freckle chain grains, equiax grains, and a new grain formed in surface scale, had been investigated. The grain boundary regions were observed by high resolution electron microscopy. Although the formation mechanism of each grain defect is different, secondary phases, such as rhenium-rich particles, have been always found in each grain boundary. In addition, depending on the existence of the secondary phases as well as the size of defect grains, different microstructures were observed even in the same defect grain boundary. Finally, the observed results suggest that if there is any boundary region in a turbine blade, secondary phases, such as Re-rich particles, can be found.

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Yang, Y., Tomonrori Kitashima, T. Hara, Y. Hara, Yoko Yamabe-Mitarai, M. Hagiwara, and L. J. Liu. "Effect of Grain Size on Oxidation Resistance of Unalloyed Titanium." Materials Science Forum 879 (November 2016): 2187–91. http://dx.doi.org/10.4028/www.scientific.net/msf.879.2187.

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The effect of the grain size on the high-temperature oxidation resistance of unalloyed titanium was experimentally investigated using titanium samples with two different grain sizes of 219 μm and 118 μm. The weight gain during oxidation and the penetration depth of oxygen from a metal surface were larger in the small-grain-size sample compared with the large-grain-size sample. In addition, oxygen diffusion was faster in the substrate of the small-grain-size sample. These results were attributed to the grain-boundary diffusion of oxygen. A steep change in the oxygen concentration was observed at a grain boundary. Our simulation results suggested that slower oxygen diffusion into the inner grain from the surface through the grain boundary with high diffusivity can cause the observed steep change in the oxygen concentration.

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Alles, Aldo B., and Vernon L. Burdick. "Grain Boundary Oxidation in PTCR Barium Titanate Thermistors." Journal of the American Ceramic Society 76, no. 2 (February 1993): 401–8. http://dx.doi.org/10.1111/j.1151-2916.1993.tb03798.x.

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Kang, Jaewoon, and Hongsik Park. "Evaluation Method for Graphene Grain Boundary by UV/ozone-oxidation Chemical-etching Process." Journal of Sensor Science and Technology 25, no. 4 (July 31, 2016): 275–79. http://dx.doi.org/10.5369/jsst.2016.25.4.275.

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Fujikawa, Hisao. "Review of Several Studies on High Temperature Oxidation Behaviour and Mechanism of Austenitic Stainless Steels." Defect and Diffusion Forum 312-315 (April 2011): 1097–105. http://dx.doi.org/10.4028/www.scientific.net/ddf.312-315.1097.

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Three studies on the oxidation behaviour of austenitic stainless steels were described in the present paper. (1) High temperature oxidation behaviour and its mechanism in austenitic stainless steels with high silicon: Sulfur contained as impurity in steel showed a harmful influence to the oxidation resistance of 19Cr-13Ni-3.5Si stainless steels. It was found that the abnormal oxidation was caused from the surroundings of MnS inclusions. (2) Effect of a small addition of yttrium on high temperature oxidation resistance of Si-containing austenitic stain less steels: The oxidation resistance of 19Cr-10Ni-1.5Si steels was improved remarkably even with only 0.01%Y addition, which is the same concentration as added for de-oxygenation. Y was enriched at the grain boundary of oxide scale and metal-oxide interface. It was suggested that Y-containing steels shoed good oxidation resistance, because the enriched Y at the grain boundary and metal-oxide interface prevented the diffusion of iron and oxygen ions through the oxide scale. (3) Effect of grain size on the oxidation behaviour of austenitic stainless steels: Type 304, 316 and 310 steels with finer grain size showed better oxidation resistance than those with coarser grain size at 850°C. The oxide scale of steels with coarser grain size easily spalled during the cooling process.

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Li, Lv, Xiaojuan Gong, Xianjue Ye, Jianwei Teng, Yan Nie, Yunping Li, and Qian Lei. "Influence of Building Direction on the Oxidation Behavior of Inconel 718 Alloy Fabricated by Additive Manufacture of Electron Beam Melting." Materials 11, no. 12 (December 14, 2018): 2549. http://dx.doi.org/10.3390/ma11122549.

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This research was aimed at investigating the high temperature oxidation behavior of Inconel 718 superalloy fabricated by electron beam melting with the building direction of 0°, 55° and 90° deviation from the Z axis of cylindrical samples. Columnar γ-fcc phase with preferred crystal orientations was found in all specimens. With the temperature ranging from 700 to 1000 °C, the 0° sample, symbolized by the lowest grain boundary density, and largest grain size, reveals the best oxidation performance. It is concluded that the building direction has more impact on the amount of grain boundary density than crystal orientation, which determined the oxidation resistance.

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Дисертації з теми "Grain boundary oxidation"

Soontrapa, Chaiyod. "Modeling stress accelerated grain boundary oxidation (SAGBO) in INCOLOY alloy 908." Thesis, Massachusetts Institute of Technology, 2005. http://hdl.handle.net/1721.1/33613.

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Thesis (S.M.)--Massachusetts Institute of Technology, Dept. of Materials Science and Engineering, 2005.
Includes bibliographical references (p. 57-59).
This study explores the possibility of extending the Ph.D. work of Yan Xu on copper-tin alloys (University of Pennsylvania, 1999) to model stress accelerated grain boundary oxidation (SAGBO) in INCOLOY alloy 908. The steady state model involves the embrittlement along the grain boundary due to oxygen diffusion with the concentration gradient and the stress field ahead of the crack tip as the driving forces. As oxygen forms brittle phases with the segregates in the grain boundary, it reduces the cohesive strength of the grain boundary and causes intergranular cracking in the material. The extensions to the original model include (1) dependence of oxygen concentration at crack tips on oxygen partial pressure and (2) a new creep law specific to nickel-based superalloys. While the steady state model correctly indicates temperature as one of three leading factors in SAGBO, it fails to capture the effects of the two remaining factors: applied loading and oxygen partial pressure.
by Chaiyod Soontrapa.
S.M.

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Cisloiu, Cezar. "High temperature stress accerated grain boundary oxidation mechanism on INCONEL 783 superalloy." Morgantown, W. Va. : [West Virginia University Libraries], 2001. http://etd.wvu.edu/templates/showETD.cfm?recnum=1907.

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Thesis (M.S.)--West Virginia University, 2001.
Title from document title page. Document formatted into pages; contains vii, 64 p. : ill. (some col.). Includes abstract. Includes bibliographical references (p. 62-64).

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Agrizzi, Ronqueti Larissa. "Study of grain boundary oxidation of high alloyed carbon steels at coiling temperature." Thesis, Compiègne, 2018. https://bibliotheque.utc.fr/Default/doc/SYRACUSE/2018COMP2405.

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Les aciers à haute résistance (AHSS) ont été largement utilisés dans le cadre d’applications automobiles visant à améliorer la sécurité et l’allègement des structures. Afin d'atteindre les objectifs en termes de propriétés mécaniques, ces nouveaux aciers sont composés de teneurs en éléments d’alliages beaucoup plus élevés (par exemple silicium et manganèse) que les aciers usuels. En conséquence, l'AHSS est susceptible de subir une oxydation interne sélective lors du refroidissement des bobines d’acier. L'oxydation sélective interne, en particulier l'oxydation aux joints de grains (GBO), est actuellement l'un des principaux obstacles à la production de ces aciers. Elle réduit le nombre de cycles avant la rupture de fatigue et rend ainsi difficile l’obtention des spécifications du client. Par conséquent, ce travail de thèse était axé sur l'effet de plusieurs paramètres sur le comportement à l’oxydation interne sélective. Parmi eux, l'impact de la décarburation, l'influence de la température de bobinage et de la couche de calamine, l'effet de différentes teneurs en silicium et / ou en manganèse et leur comportement en diffusion. De plus, l'impact de la désorientation des joints de grains sur l'oxydation interne a également été étudié. Des alliages modèles à base de fer binaires / ternaires ainsi que des aciers industriels ont été étudiés via un large ensemble de techniques expérimentales. Ces analyses ont mis en évidence une décarburation stable pour tous les échantillons étudiés qui n'a pas d'impact sur l'oxydation interne sélective pour une longue exposition aux conditions isothermes. Les profondeurs d’oxydation aux joints de grain ont été examinées selon les différentes configurations de tests et se sont révélées sensibles aux teneurs en silicium ou en manganèse. Pour certaines d'entre elles, différents comportements de diffusion du silicium ont été identifiés vis-à-vis de l'oxydation des joints de grains, en fonction des températures. Considérant quelques hypothèses restrictives, l'application de la théorie de l'oxydation interne sélective de Wagner a permis de déterminer le coefficient de diffusion de l'oxygène aux joints de grain. Pour surmonter certaines limites du modèle de Wagner, un modèle d'oxydation sélective a été appliqué pour comprendre l'effet de différents paramètres sur la pénétration de l'oxygène à l'intérieur du métal et principalement sur la profondeur des joints de grain affectée par l'oxydation sélective. Les connaissances acquises à partir de ce travail de thèse aideront à comprendre et à limiter l'oxydation sélective interne (principalement l’oxydation aux joints de grain) dans les aciers avec des compositions complexes en éléments d’alliage. En outre, les résultats peuvent être utilisés pour évaluer les paramètres d’un modèle d'oxydation sélective
Advanced high-strength steels (AHSS) have been widely used in automotive industry to improve safety and fuel economy. In order to reach the mechanical properties targets, these new steels are composed by much higher alloy contents (e.g. silicon and manganese) than usual steels. As consequence, the AHSS may suffer of selective internal oxidation during the cooling of hot coil. The selective internal oxidation, especially the grain boundary oxidation (GBO), is currently one of the main obstacles to the production of these steels. It reduces the number of cycles before fatigue failure and thus, makes it difficult to reach the specifications of the customer. Therefore, this PhD work was focused on the effect of several parameters on selective internal oxidation behavior. Among them, the impact of decarburization, the influence of coiling temperature and the mill scale, the effect of different silicon and/or manganese contents and their diffusion behavior. Moreover, the impact of grain boundary misorientation on grain boundary oxidation was also investigated. Either binary/ternary iron-based model alloys as well as industrial steels were investigated by a large set of experimental techniques. This analysis showed a stable decarburization for all investigated samples that does not impact the selective internal oxidation for long exposure time in isothermal conditions. The GBO depths were examined according to the different test configurations and were found dependent for some cases on silicon or manganese content. For some of them, different silicon diffusion behaviors were identified with regards to grain boundary oxidation depending on temperatures. Considering some restrictive hypotheses, the application of Wagner’s theory of selective internal oxidation allowed determining the grain boundary diffusion coefficient of oxygen. To overcome some limitations of Wagner’s model, a model of selective oxidation has been applied to understand the effect of different parameters on the penetration of oxygen inside the metal and principally on the grain boundary depth affected by selective oxidation. The knowledge acquired from this PhD work will help to understand and limit the selective internal oxidation (mainly GBO) in new steels with complex alloy compositions. Furthermore, the results may be used to assess a model of selective oxidation

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Thorning, Casper. "Grain Boundary Ridge Formation during High Temperature Oxiditation of Manganese Containing Steels." Doctoral thesis, KTH, Materialvetenskap, 2008. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-4778.

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Thorning, Casper. "Grain boundary ridge formation during initial high temperature oxidation of Mn/Al TRIP steel /." Stockholm, 2006. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-4081.

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Morra, Martin M. (Martin Mathew). "Stress accelerated grain boundary oxidation of incoloy alloy 908 in high temperature oxygenous atmospheres." Thesis, Massachusetts Institute of Technology, 1995. http://hdl.handle.net/1721.1/11513.

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Dohr, Judith. "Micromechanical testing of oxidized grain boundaries." Thesis, University of Oxford, 2016. https://ora.ox.ac.uk/objects/uuid:fb8a08ef-87d8-47ab-9ac8-89bf300203ea.

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Primary water stress corrosion cracking (SCC) of metals in pressurized water reactors (PWRs) is known to be one of the most challenging and cost intensive modes of failure in the nuclear industry. Even though it is known that cracking in Ni-base alloys proceeds mainly intergranular (IG), the initiation and propagation of cracks in ductile metals are not yet understood and a much-desired accurate prediction of SCC related failure seems unobtainable. In this thesis, a combination of microcantilever fracture experiments, scanning electron- (SEM) and transmission electron microscopy (TEM) techniques was employed to study and compare the failure of oxidized grain boundaries of Ni-base Alloy 600 with high and low intergranular carbide coverage and different sample history. A new technique for lifting-out whole cantilevers after testing and for performing 3D focussed ion beam sequencing (3D FIB-SEM) while preserving a thin central region of the cantilever for further TEM sample preparation was developed and is presented. In lieu with recent efforts of the main project sponsor Électricité de France (EDF) to build a predictive model for IGSCC based on localized/microscopic information, one of the main objectives was the extraction of the stress at failure of individual oxidized GBs. Supported by finite element simulations, microcantilever fracture tests revealed that surface oxides on top of individual GBs have the capability to alter the mechanical response by delaying/suppressing the onset of failure. An overestimation of the failure stress (> 230 MPa) was observed, proving that the presence of the surface oxide on top of the test structures cannot be neglected. The failure stress on both samples, tested without influence of the surface oxide, was found to cover a range of 300 - 600 MPa, which agreed well with finite element simulations of the tests and further demonstrates the reliability of the obtained data. The second objective was to gain a better understanding of the observed fracture behaviour and the role of local microstructure. Using the gathered microscopy data, it was found that the crack clearly favours a progression along the IG oxide-metal interface in the presence of carbide precipitates. Electron energy loss spectroscopy (EELS) revealed that the observed crack path can be linked to compositional and density variations of the IG oxide. In the presence of carbides the oxide was layered. An oxide close to the stoichiometry of chromia was located at the original GB and next to the carbides. Next to this Cr-rich oxide, Fe-rich mixed spinel oxides of varying composition and density were found. An explanation for density variations based on the possible formation of defective spinel oxides of the type A²⁺B³⁺₂O₄, due to an unavailability of certain cation species is presented. No clear interface preference was observed in the absence of precipitation, where the IG oxide was found to be thin and often incomplete with Cr-richer oxides preferentially located at the original GB. While these observations were consistent on both samples (high and low carbide coverage), bigger void-like defects were located at the Fe-richer oxide-metal interface of the cold worked sample with high IG carbide precipitation only. These weak spots seemed to be the preferred path for crack propagation on this sample. The sample with low intergranular carbide coverage showed no obvious porosities at this interface but a Cr- depleted region was seen. Introducing a multi-faceted investigation strategy, supported by finite element simulations, the presented thesis provides the most accurate determination of the failure stress of oxidized GBs on Alloy 600 to date and and adds new valuable insights to our understanding of IGSCC and the future prediction of SCC related failures.

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Bertali, Giacomo. "Mechanistic understanding of Alloy 600 preferential intergranular oxidation : 'precursor events of stress corrosion cracking'." Thesis, University of Manchester, 2016. https://www.research.manchester.ac.uk/portal/en/theses/mechanistic-understanding-of-alloy-600-preferential-intergranular-oxidation-precursor-events-of-stress-corrosion-cracking(db6c7668-7cf5-4d50-a6bf-34eacf5b1216).html.

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Primary Water Stress Corrosion Cracking (PWSCC) of Alloy 600 and similar Ni-Cr-Fe alloys is regarded as one of the most important challenges to nuclear power plant operation. During the past decades the majority of research has focused on PWSCC crack growth rate measurements in order to assess the lifetime of real components and to develop empirical models for crack propagation. However, the incubation and initiation stages of PWSCC have the same or even greater importance than the propagation stage, particularly because SCC can be undetected for more than 20 years before the occurrence of a rapid and catastrophic failure. There is, therefore, the scientific need to understand the mechanisms playing a fundamental role in the formation and development of intergranular cracks embryo, the so-called SCC initiation "precursor events", in order to be able to predict and mitigate the occurrence of PWSCC. Amongst all the models proposed for SCC initiation, the internal oxidation mechanism proposed by Scott and Le Calvar in 1992 appears to be the most comprehensive. Although the internal oxidation mechanism is widely accepted, it still requires further elucidation, especially in terms of enhanced grain boundary diffusivity and the role of intergranular carbides on the oxidation mechanism. The present work has focused on the initial stages of intergranular oxidation of solution-annealed (SA) and thermally-treated (TT) Alloy 600 with the aim of understanding the active mechanism responsible for the enhanced intergranular oxide penetration kinetics. The material was tested in simulated PWR primary water at 320°C, high-pressure hydrogenated-steam at 400°C and low-pressure H2-steam environment at 480°C at potential more reducing than the Ni/NiO equilibrium. The detailed microstructural characterization was conducted using scanning electron microscopy (SEM), transmission electron microscopy (TEM) and analytical transmission electron microscopy (ATEM) and demonstrated that Alloy 600SA is susceptible to diffusion-induced grain boundary migration (DIGM), preferential intergranular oxidation (PIO) and localised Cr and Fe depletions at the grain boundaries. The similar analyses performed on Alloy 600TT demonstrated reduced susceptibility to PIO and grain boundary migration. Further, detailed analyses confirmed that intergranular carbides were readily oxidized/consumed in all 3 environments and acted as Cr reservoir/O trap. These results shed additional light on the "precursor events" for PWSCC of Alloy 600, especially on the mechanism responsible for the enhanced Cr and O diffusivity and on the mechanism responsible for the enhanced Alloy 600TT SCC initiation resistance. Moreover, the strong similarities in the Alloy 600 oxidation behaviour observed for the 3 different environments and at the 3 different temperatures suggested that the same PIO mechanism is active in both steam and water and at temperatures between 320°C and 480°C. These results strongly support the possibility of using the low-pressure H2-steam environment as a substitute environment to accelerate PWSCC initiation without changing the mechanism.

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Lindsay, John Christopher. "Stress corrosion cracking and internal oxidation of alloy 600 in high temperature hydrogenated steam and water." Thesis, University of Manchester, 2015. https://www.research.manchester.ac.uk/portal/en/theses/stress-corrosion-cracking-and-internal-oxidation-of-alloy-600-in-high-temperature-hydrogenated-steam-and-water(1d6b037c-baf1-4397-a6c9-43835e7bb39a).html.

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In this study, the possibility of using low pressure hydrogenated steam to simulate primary water reactor conditions is examined. The oxides formed on Alloy 600 (WF675) between 350 Celsius and 500 Celsius in low pressure hydrogenated steam (with a ratio of oxygen at the Ni/NiO to oxygen in the system of 20) have been characterised using analytical electron microscopy (AEM) and compared to oxide that formed in a high pressure water in a autoclave at 350 Celsius with 30 cc/kg of hydrogen. Preferential oxidation of grain boundaries and bulk internal oxidation were observed on samples prepared by oxide polishing suspension (OPS). Conversely, samples mechanically ground to 600 grit produced a continuous, protective oxide film which suppressed the preferential and internal oxidation. The surface preparation changed the form of the oxides in both steam and autoclave tests. The preferential oxidation rate has been determined to be K_{oxide} = Aexp{-Q/RT}with A = 2.27×10^(−3) m^(2)s^(−1) and Q = 221 kJ.mol^(−1) (activation energy) for WF675 and A = 5.04 × 10^(−7) m^(2)s^(−1) and Q = 171 kJ.mol^(−1) for 15% cold worked WF675. These values are consistent with the activation energy of primary water stress corrosion cracking (PWSCC) initiation. Bulk oxygen diffusivities were calculated from the internal oxidation after 500 h exposures. At 500 Celsius the oxygen diffusivity was determined to be 1.79×10^(−20) m^(2)s^(−1) for WF675 and 1.21×10^(−20) m^(2)s^(−1) for 15% cold worked WF675, the oxygen diffusivity at 400 Celsius in 15% cold worked WF675 was calculated to be 1.49×10^(−22) m^(2)s^(−1).The Cr-depletion associated with preferential oxidation has been assessed by AEM. The Cr-depletion was asymmetric and it could not be accounted for by local variations in the diffusion rate. Chemically induced grain boundary migration is suggested as a possible explanation. Constant load SCC tests conducted in hydrogenated steam at 400 Celsius have shown a similar trend to the classical dependency of PWSCC as a function of potential. The SCC samples were also prepared with two surface finishes, OPS and 600 grit. In all SCC tests, significantly more cracking was observed on the OPS surface and all failures initiated from this surface.

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Tao, Liang. "Atomic-scale calculations of interfacial structures and their properties in electronic materials." The Ohio State University, 2005. http://rave.ohiolink.edu/etdc/view?acc_num=osu1127163029.

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Книги з теми "Grain boundary oxidation"

Yoshiki, Oshida, and United States. National Aeronautics and Space Administration, eds. Grain boundary oxidation and fatigue crack growth at elevated temperatures. [Washington, DC: National Aeronautics and Space Administration, 1986.

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Частини книг з теми "Grain boundary oxidation"

Yamaura, S., Y. Igarashi, S. Tsurekawa, and T. Watanabe. "Grain Boundary Engineering for the Control of Oxidation Embrittlement." In Properties of Complex Inorganic Solids 2, 27–37. Boston, MA: Springer US, 2000. http://dx.doi.org/10.1007/978-1-4615-1205-9_3.

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Fujii, Katsuhiko, Terumitsu Miura, Hiromasa Nishioka, and Koji Fukuya. "Degradation of Grain Boundary Strength by Oxidation in Alloy 600." In 15th International Conference on Environmental Degradation of Materials in Nuclear Power Systems-Water Reactors, 1447–58. Hoboken, New Jersey, Canada: John Wiley & Sons, Inc., 2012. http://dx.doi.org/10.1002/9781118456835.ch151.

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Xu, Peng, Liang Y. Zhao, Kumar Sridharan, and Todd R. Allen. "Grain Boundary Engineering and Air Oxidation Behavior of Alloy 690." In 15th International Conference on Environmental Degradation of Materials in Nuclear Power Systems-Water Reactors, 1951–63. Hoboken, New Jersey, Canada: John Wiley & Sons, Inc., 2012. http://dx.doi.org/10.1002/9781118456835.ch202.

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Xu, Peng, Liang Y. Zhao, Kumar Sridharan, and Todd R. Allen. "Grain Boundary Engineering and Air Oxidation Behavior of Alloy 690." In Proceedings of the 15th International Conference on Environmental Degradation of Materials in Nuclear Power Systems — Water Reactors, 1951–65. Cham: Springer International Publishing, 2011. http://dx.doi.org/10.1007/978-3-319-48760-1_117.

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Fujii, Katsuhiko, Terumitsu Miura, Hiromasa Nishioka, and Koji Fukuya. "Degradation of Grain Boundary Strength by Oxidation in Alloy 600." In Proceedings of the 15th International Conference on Environmental Degradation of Materials in Nuclear Power Systems — Water Reactors, 1447–61. Cham: Springer International Publishing, 2011. http://dx.doi.org/10.1007/978-3-319-48760-1_89.

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Fukumura, Takuya, Koji Fukuya, Katsuhiko Fujii, Terumitsu Miura, and Yuji Kitsunai. "Grain Boundary Oxidation of Neutron Irradiated Stainless Steels in Simulated PWR Water." In The Minerals, Metals & Materials Series, 937–47. Cham: Springer International Publishing, 2017. http://dx.doi.org/10.1007/978-3-319-68454-3_68.

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Fukumura, Takuya, Koji Fukuya, Katsuhiko Fujii, Terumitsu Miura, and Yuji Kitsunai. "Grain Boundary Oxidation of Neutron Irradiated Stainless Steels in Simulated PWR Water." In The Minerals, Metals & Materials Series, 2153–63. Cham: Springer International Publishing, 2017. http://dx.doi.org/10.1007/978-3-030-04639-2_144.

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Barbier, Françoise, Jean Bernardini, Fernand Moya, and Michel Déchamps. "Grain Boundary Diffusion Artefacts in Polycrystalline Nickel Oxide Grown by High Temperature Oxidation." In Ceramic Microstructures ’86, 549–54. Boston, MA: Springer US, 1987. http://dx.doi.org/10.1007/978-1-4613-1933-7_56.

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Morra, M. M., S. Nicol, L. Toma, I. S. Hwang, M. M. Steeves, and R. G. Ballinger. "Stress Accelerated Grain Boundary Oxidation of Incoloy Alloy 908 in High Temperature Oxygenous Atmospheres." In Advances in Cryogenic Engineering Materials, 1291–98. Boston, MA: Springer US, 1994. http://dx.doi.org/10.1007/978-1-4757-9053-5_164.

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Sueishi, Y., M. Takeyama, and H. Tezuka. "Effect of Grain-Boundary Fe2Nb Phase on Stress-Assisted Grain-Boundary Oxidation Behavior in Novel Austenitic Heat-Resistant Steel of Fe-20Cr-35Ni-2.5Nb." In Proceedings of the 9th International Symposium on Superalloy 718 & Derivatives: Energy, Aerospace, and Industrial Applications, 477–87. Cham: Springer International Publishing, 2018. http://dx.doi.org/10.1007/978-3-319-89480-5_30.

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Тези доповідей конференцій з теми "Grain boundary oxidation"

Ronqueti, Larissa Agrizzi, Jérôme Favergeon, Marion Risbet, and Michel Picard. "STUDY OF GRAIN BOUNDARY OXIDATION OF HIGH ALLOYED CARBON STEELS AT COILING TEMPERATURE." In 53º Seminário de Laminação. São Paulo: Editora Blucher, 2017. http://dx.doi.org/10.5151/1983-4764-27735.

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Selvig, Austin, Xiao Huang, Mike Hildebrand, and David Stek. "Investigation of Stress Assisted Grain Boundary Oxidization (SAGBO) Cracking in Mar-M002 High Pressure Turbine Blades." In ASME Turbo Expo 2010: Power for Land, Sea, and Air. ASMEDC, 2010. http://dx.doi.org/10.1115/gt2010-22145.

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Modern superalloys have enabled High Pressure Turbine (HPT) blades in Gas Turbine Engines (GTE) to operate at higher temperatures. Unfortunately the complexity of these materials can make it difficult to understand the failure mechanisms of these blades. HPT blades made of the nickel based superalloy Mar-M002 have been found to suffer from Stress Assisted Grain Boundary Oxidation (SAGBO) cracking. HPT blades removed from an RB211-24C aero-derivative industrial GTE were sectioned and the cracks and microstructure were studied using Scanning Electron Microscopy (SEM) and Energy Dispersive X-ray Spectroscopy (EDS). No cracks were found on the external surface of the blade which had been coated with an oxidation resistant material. Surface irregularities were found along the walls of the inner cooling channels throughout the entire blade. Larger SAGBO cracks were observed to be near the lower 25% span of the blade and had initiated from the surfaces of the cooling channels. SEM/EDS analysis showed that these cracks had large amounts of alumina and Hafnium-rich particles within them. It is evident that these cracks occurred in locations where the combination of high stress and high temperature led to higher rates of oxygen diffusion and subsequent oxidation of grain boundary carbides. Hafnium Carbide precipitates along the grain boundaries expanded as they converted into Hafnium Oxide, thus further increasing the stress. It is envisaged that this increase in stress along the grain boundary has caused the cracks to initiate and coalesce. Based on this observation, it is believed that the inner cooling channels of these HPT blades could benefit from the application of an oxidation resistant coating in order to prevent or delay the formation of these cracks.

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Alperine, S., and L. Lelait. "Microstructural Investigations of Plasma Sprayed Yttria Partially Stabilized Zirconia TBC: in Relation to Thermomechanical Resistance and High Temperature Oxidation Mechanisms." In ASME 1992 International Gas Turbine and Aeroengine Congress and Exposition. American Society of Mechanical Engineers, 1992. http://dx.doi.org/10.1115/92-gt-317.

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This study deals with microstructural investigations of plasma sprayed yttria partially stabilized zirconia thermal barrier coatings, performed by classical and analytical transmission electron microscopy. The aim of the study was to determine eventual relationships between coating microstructure and toughness. The ceramic/metal interface which plays an important role during TBC thermomechanical sollicitation, has also been studied. In the 6 to 8 weight % Y2O3 range, the metastable tetragonal t’ phase is observed, showing special faulted microstructural features, such as grain twinning and antiphase boundary planes. Moreover, after high temperature annealing in air, a very fine and stable precipitation of the equilibrium cubic phase appears. It is believed that these microstructural elements could act as crack deviation sites and enhance coatings intrinsic toughness. Microstructural investigations of the alumina scales grown during high temperature annealing reveal yttrium segregation at oxide grain boundaries as well as significant quantities of zirconium inside the alumina grains. The oxide growth seems to be dominated by a classical grain boundary oxygen diffusion mechanism. The presence of zirconium inside the alumina grains suggests that Al2O3 also partially forms by chemical reduction of ZrO2 by Al.

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Hollis, K. J., D. P. Butt, and R. G. Castro. "Impression Creep Behavior of Atmospheric Plasma-Sprayed and Hot Pressed MoSi2/Si3N4." In ITSC 1997, edited by C. C. Berndt. ASM International, 1997. http://dx.doi.org/10.31399/asm.cp.itsc1997p0751.

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Abstract The use of MoSi2 as a high temperature oxidation resistant structural material is hindered by its poor elevated temperature creep resistance. The addition of second phase Si3N4 holds promise for improving the creep properties of MoSi2 without decreasing oxidation resistance. The high temperature impression creep behavior of atmospheric plasma sprayed (APS) and hot pressed (HP) MoSi2/Si3N4 composites was investigated. Values for steady state creep rates, creep activation energies, and creep stress exponents were measured. Grain boundary sliding and splat sliding were found to be the dominant creep mechanisms for the APS samples while grain boundary sliding and plastic deformation were found to be the dominant creep mechanisms for the HP samples.

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Wagenhuber, E. G., V. B. Trindade, and U. Krupp. "The Role of Oxygen-Grain-Boundary Diffusion During Intercrystalline Oxidation and Intergranular Fatigue Crack Propagation in Alloy 718." In Superalloys. TMS, 2005. http://dx.doi.org/10.7449/2005/superalloys_2005_591_600.

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Cheruvu, N. Sastry, Ronghua Wei, and David W. Gandy. "Oxidation Behavior of Sputter Deposited Nanocrystalline and Conventional Plasma Sprayed MCrAl(Y) Coatings." In ASME Turbo Expo 2010: Power for Land, Sea, and Air. ASMEDC, 2010. http://dx.doi.org/10.1115/gt2010-22645.

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The MCrAl-type coatings with, or without, yttrium are widely used for oxidation and/or hot corrosion protection of hot section components of gas turbine engines. Recently, there has been great interest in developing nano or microcrystalline coatings since these coatings offer excellent oxidation and corrosion resistance compared to the conventional coatings. Cyclic oxidation and microstructral degradadation behavior of sputter deposited nanocrystalline Ni-20Cr-10Al coating has been investigated at 1010°C. The coating was deposited on Haynes 230 samples using a magnetron sputtering technique. This technique produced a coating with a grain size of ∼9 nm. The cyclic oxidation results showed that the sputter deposited Ni-20Cr-10Al coating exhibited better oxidation resistance in terms of weight loss kinetics compared to the conventional plasma-sprayed NiCoCrAlY and PWA 286 coatings. The Al content in the nanocrystalline coating was consumed in a relatively short time due to inward and outward diffusion of Al. The accelerated consumption of Al was presumably due to enhanced grain boundary diffusion resulting from the ultra-fine grain structure in the coating. Variation of oxide-scale spallation resistance during thermal cycling, internal oxidation of the coatings, and the rate of Al consumption due to inward and outward diffusion of Al between the nanocrystalline and plasma sprayed coatings is presented.

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Chen, Tao, Xuedong Chen, Chunjiao Liu, Juan Ye, and Defu Nie. "Carburization of Ethylene Pyrolysis Furnace Tube in a Petrochemical Plant." In ASME 2014 Pressure Vessels and Piping Conference. American Society of Mechanical Engineers, 2014. http://dx.doi.org/10.1115/pvp2014-28671.

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Carburization phenomena of the ethylene pyrolysis furnace tube made of 25Cr35NiNb alloy was investigated after service for approximate 30,000h in a petrochemical plant. Three different zones, namely oxidation zone, carburization zone and aging product zone, were observed in the cross section of furnace tube by microscopic analysis. The oxidation zone near the inner surface has a thickness of about 700μm and possesses the characterization of many loose pores and voids. The inner surface has a continuous thin Cr2O3 layer and the grain boundaries near the inner wall are mainly composed of mixed oxides of Cr2O3 and SiO2. In addition, segregation of impurities S and P were detected at grain boundaries. The dark grey SiO2 distributes in front of the oxidation zone. Carbides distribute at grain boundaries in the carburization zone with lots of voids and micro cracks. The width of grain boundary is broadened. According to the experimental results, the initiation of cracks may be promoted by carbides at grain boundaries. The uneven distribution of the Cr element was found in the carburization zone, and direct experimental evidence of Cr element diffusion was detected. In the aging product zone, the carbides evolution was observed. The chromium carbides are composed of Cr7C3 and Cr23C6. The microstructure and composition evolutions of the furnace tube and their effects on service life of ethylene pyrolysis furnace tube were also discussed in this paper.

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Feng, Chuanyu, Bruce S. Kang, Ning Ma, and Bernard R. Cooper. "Study of Fracture Behavior of Molybdenum Alloys Using Moire´ Interferometry." In ASME 2005 International Mechanical Engineering Congress and Exposition. ASMEDC, 2005. http://dx.doi.org/10.1115/imece2005-81221.

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Molybdenum-based intermetallics are currently being developed for high temperature application (>1000°C) in advanced fossil energy combustion systems. The goal is to maintain the desired high-temperature mechanical properties while also achieving the required high-temperature oxidation/ hot corrosion resistance. In this research, molybdenum alloys were investigated using high temperature moire´ interferometry. Three-point-bending tests were conducted, and detailed fracture behavior around crack tip was investigated at both room temperature and elevated temperature. Grain boundary sliding was observed through high resolution in-plane deformation fields. For each test, a follow-up fractography and microstructural analyses were carried out. Test results showed that molybdenum alloy with silicide has higher toughness and enhanced grain boundary strength at elevated temperature. The effect of oxygen on grain boundary cohesive strength of Mo alloy was also studied using atomistic modeling and simulations.

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Kobayashi, Daisuke, Akihiro Ito, Masamichi Miyabe, Yukio Kagiya, and Yomei Yoshioka. "Crack Initiation Behavior and its Estimation for a Gas Turbine Rotor Based on the EBSD Analysis." In ASME Turbo Expo 2012: Turbine Technical Conference and Exposition. American Society of Mechanical Engineers, 2012. http://dx.doi.org/10.1115/gt2012-68226.

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Gas turbine rotors made of Ni-base superalloys were sometimes found to have cracks at the dovetail of the first and second stage wheel. In order to maintain the reliability of gas turbine rotors over the long term, in addition to the application of countermeasures such as the shot-peening process, it is essential to confirm the characteristics of crack initiation mechanisms and to predict the possibility of new cracking. In this paper, first, the case study of crack initiation concerning a wheel dovetail crack has been carried out. Second, to reveal the characteristics of the crack, comparative evaluation between the actual crack and various mechanical fracture samples were conducted by using a scanning electron microscope (SEM) and the electron back-scatter diffraction (EBSD) method which can analyze crystallographic misorientation. As a result, it was found that even in relatively low temperatures, Inconel® Alloy 706 is subjected to brittle grain boundary oxidation when under constant high stress, i.e. a similar phenomenon to stress accelerated grain boundary oxidation (SAGBO), so called hold-time cracking (HTC).

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Tan, Taide, and Yitung Chen. "Simulations of Metal Oxidation in LBE at a Mesoscopic Level." In 16th International Conference on Nuclear Engineering. ASMEDC, 2008. http://dx.doi.org/10.1115/icone16-48025.

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The oxidation process of metals in lead bismuth eutectic (LBE) environment is studied at a mesoscopic scale. An improved stochastic cellular automaton model based on an improved Moore neighborhood is proposed to investigate the development of a continuous oxide layer of metals in LBE. The ionization of metal and the oxidation reaction were simulated with consideration of the transport of oxygen along the grain boundary and the diffusion of metallic ions. The growth of oxide layer in two directions is observed and the volume expansion effect can be realized by changing the volume control parameter. The model was benchmarked with a pure diffusion process, both with the analytical solution and with the previous work. Significant agreement was reached between the data. The developed model is also mapped with the experimental data from an LBE loop. A parametric study was conducted in order to check the importance of the main explicit parameters of the mesoscopic model.

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