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Littérature scientifique sur le sujet « Microstructures γ-γ' »

Auteur : Grafiati

Publié le 8 mars 2025

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Articles de revues sur le sujet "Microstructures γ-γ'"

Mohanty, R. R., et Yong Ho Sohn. « Phase Field Modeling of Interdiffusion Microstructure in Ni-Cr-Al Diffusion Couples ». Materials Science Forum 595-598 (septembre 2008) : 199–206. http://dx.doi.org/10.4028/www.scientific.net/msf.595-598.199.

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Evolution of interdiffusion microstructures was examined in ternary Ni-Cr-Al solid-tosolid diffusion couples using two-dimensional (2D) phase field simulation. Utilizing Cahn-Hilliard and Allen-Cahn equations, multiphase diffusion couples containing of fcc-γ and B2-β solid solution phases were simulated with alloys of different compositions and phase contents. Chemical mobility as a function of composition with constant gradient energy coefficients was used in the simulation. Simulated microstructures in γ+β/γ and γ+β/γ+β diffusion couples were compared with the experimental microstructures reported in literature. As observed experimentally, the model predicted the recession of γ+β region in the γ+β/γ couple and a stationary interface in γ+β/γ+β couple. Concentration profiles developed across the diffusion couples demonstrated that the interdiffusion occurs in the γ phase as well as in the γ+β region. Formation of single-phase γ and β layers near the interface of γ+β/γ+β couples was also investigated using the volume fraction profile obtained from the simulated microstructure.

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Xue, Yan Peng, Xiao Guang Wang, Jin Qian Zhao, Zhen Xue Shi, Shi Zhong liu et Jia Rrong Li. « Effect of Heat Treatment on Microstructure Evolution in DD9 Single Crystal Turbine Blade ». Materials Science Forum 1072 (25 octobre 2022) : 95–102. http://dx.doi.org/10.4028/p-26qh91.

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The microstructural evolution of DD9 single crystal superalloy turbine blade was studied after heat treatment. In comparison to the as-cast microstructures where the sizes of the γ′ precipitates have an obvious difference between the dendritic core and interdendritic regions, the γ′ sizes of the heat-treated microstructures tend to be uniform and more cubic. And in the heat-treated microstructures, the γ′ sizes and the related size dispersion degrees of the dendritic cores are slightly increased, while those of the interdendritic regions are obviously decreased. After all, all the γ′ sizes follow the normal distribution law. With the raise of section thickness, the γ′ sizes tend to increase and the related size dispersion degrees are enhanced during the cooling process after heat treatment, and the γ-γ′ eutectics are dissolved, left little residual eutectics and pores.

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Guo, X., P. He, K. Xu, P. Y. Chen, B. Chen et S. B. Huo. « Microstructural evolution and liquation cracking in the partially melted zone of deposited ERNiCrFe-13 filler metal subjected to TIG refusion ». Welding in the World 65, n^o 5 (9 février 2021) : 825–32. http://dx.doi.org/10.1007/s40194-021-01073-8.

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AbstractThe microstructure of ERNiCrFe-13 multipass weld metal has been shown to contain Laves/γ or σ/γ eutectic constituents that can increase susceptibility to solidification and weld metal liquation cracking resulting from the low eutectic reaction temperature. Under poor heat dissipation conditions such as on the edge of large thickness welded components, a partially melted zone (PMZ) may form in the weld metal during multipass welding. The microstructural evolution and liquation cracking susceptibility of this PMZ in ERNiCrFe-13 multipass welds have received little attention. In the present study, a tungsten inert gas (TIG) refusion process is used to simulate a thermal cycle with a long elevated temperature dwell time in order to investigate the microstructural evolution and liquation cracking in the weld metal PMZ. The results show that the eutectic microstructures in the PMZ evolve into three eutectic morphologies after TIG refusion, including long linear chains extending perpendicular to the boundary between the refusion zone and PMZ, skeletal structures, and fine lamellar networks. This evolution contributes to constitutional liquation occurring at the γ/Laves and γ/σ interface. Nb and Mo play a leading role in the constitutional liquation of γ/Laves and γ/σ eutectic microstructures, respectively. Liquation cracking in the PMZ is shown to occur along the linear chain grain boundaries resulting from constitutional liquation.

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Ding, Qingqing, Hongbin Bei, Xinbao Zhao, Yanfei Gao et Ze Zhang. « Processing, Microstructures and Mechanical Properties of a Ni-Based Single Crystal Superalloy ». Crystals 10, n^o 7 (3 juillet 2020) : 572. http://dx.doi.org/10.3390/cryst10070572.

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A second-generation Ni-based superalloy has been directionally solidified by using a Bridgman method, and the key processing steps have been investigated with a focus on their effects on microstructure evolution and mechanical properties. The as-grown microstructure is of a typical dendrite structure with microscopic elemental segregation during solidification. Based on the microstructural evidence and the measured phase transformation temperatures, a step-wise solution treatment procedure is designed to effectively eliminate the compositional and microstructural inhomogeneities. Consequently, the homogenized microstructure consisting of γ/γ′ phases (size of γ′ cube is ~400 nm) have been successfully produced after a two-step (solid solution and aging) treatment. The mechanical properties of the resulting alloys with desirable microstructures at room and elevated temperatures are measured by tensile tests. The strength of the alloy is comparable to commercial monocrystalline superalloys, such as DD6 and CMSX-4. The fracture modes of the alloy at various temperatures have also been studied and the corresponding deformation mechanisms are discussed.

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Wang, Chan, Duoqi Shi et Shaolin Li. « A Study on Establishing a Microstructure-Related Hardness Model with Precipitate Segmentation Using Deep Learning Method ». Materials 13, n^o 5 (10 mars 2020) : 1256. http://dx.doi.org/10.3390/ma13051256.

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This paper established a microstructure-related hardness model of a polycrystalline Ni-based superalloy GH4720Li, and the sizes and area fractions of γ’ precipitates were extracted from scanning electron microscope (SEM) images using a deep learning method. The common method used to obtain morphological parameters of γ’ precipitates is the thresholding method. However, this method is not suitable for distinguishing different generations of γ’ precipitates with similar gray values in SEM images, which needs many manual interventions. In this paper, we employ SEM with ATLAS (AuTomated Large Area Scanning) module to automatically and quickly detect a much wider range of microstructures. A deep learning method of U-Net is firstly applied to automatically and accurately segment different generations of γ’ precipitates and extract their parameters from the large-area SEM images. Then the obtained sizes and area fractions of γ’ precipitates are used to study the precipitate stability and microstructure-related hardness of GH4720Li alloy at long-term service temperatures. The experimental results show that primary and secondary γ’ precipitates show good stability under long-term service temperatures. Tertiary γ’ precipitates coarsen selectively, and their coarsening behavior can be predicted by the Lifshitz–Slyozov encounter modified (LSEM) model. The hardness decreases as a result of γ’ coarsening. A microstructure-related hardness model for correlating the hardness of the γ’/γ coherent structures and the microstructure is established, which can effectively predict the hardness of the alloy with different microstructures.

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Prakash, Aruna, et Erik Bitzek. « Idealized vs. Realistic Microstructures : An Atomistic Simulation Case Study on γ/γ′ Microstructures ». Materials 10, n^o 1 (23 janvier 2017) : 88. http://dx.doi.org/10.3390/ma10010088.

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Pan, Qinghai, Yongfeng Sui, Peijiong Yu, Xinbao Zhao, Yuan Cheng, Quanzhao Yue, Yuefeng Gu et Ze Zhang. « Effect of Heat Treatment Schedules on Creep Performance of Ni-Based Superalloy Mar-M247 at 871 °C and 250 Mpa ». Metals 13, n^o 7 (14 juillet 2023) : 1270. http://dx.doi.org/10.3390/met13071270.

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The effects of heat treatment (H1 and H2) on the creep behavior and microstructures of Mar-M247 at 871 °C/250 MPa are studied. The results show that the as-cast microstructure is composed of eutectics, γ phase, γ’ phase, MC and M23C6 carbides, while new M6C appears in heat-treated microstructures, indicating the transformation of carbides after heat treatments. The Mar-M247 is excellent, with over 1500 h of creep life, and H1 is 48% higher than H2. The addition of post-brazing and diffusion heat treatment in H2 is detrimental to creep resistance; the two steps promoted the transformation of MC into M23C6 in advance. The increase and coarsening of M23C6 would consume more γ-phase-forming elements, weakening the solution strengthening at grain boundaries. As a result, the resistance of the grain boundary and γ/γ’ interface to dislocation motion is significantly reduced, leading to the cracks’ initiation and propagation along the grain boundaries.

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KONG, FANTAO, et YUYONG CHEN. « EFFECTS OF THERMO-MECHANICAL TREATMENTS ON MICROSTRUCTURE OF Ti-43Al-9V-Y ALLOY ». International Journal of Modern Physics B 23, n^o 06n07 (20 mars 2009) : 1009–13. http://dx.doi.org/10.1142/s0217979209060385.

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Ti -43 Al -9 V - Y alloy billets was prepared by the quasi-isothermal canned forging processing, and effect of heat treatment processes on the microstructure of as-forged Ti -43 Al -9 V - Y alloy was investigated. The results show that, as-forged Ti -43 Al -9 V - Y alloy has streamline microstructure including a large number of recrystallized grains and broken lamellae, and different heat treatment processes were employed to obtain different microstructures of Ti -43 Al -9 V - Y alloy. After heat treatment at 1250°C, the microstructure of as-forged Ti -43 Al -9 V - Y alloy becomes γ+ B 2 microstructure. Comparing with the microstructure after HT of 1250°C/30 min, the precipitation of B 2 lath phase in γ equiaxed grains increased and γ grains refined after HT of 1280°C/30min or 1320°C/30min. However, after the heat treatment of 1300°C/30 min, the duplex microstructures can be gained.

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Xu, Wen Yong, Zi Chao Peng, Mu Zi Li et Minh Son Pham. « Microstructure Analysis and Creep Behaviour Modelling of Powder Metallurgy Superalloy ». Materials Science Forum 913 (février 2018) : 134–40. http://dx.doi.org/10.4028/www.scientific.net/msf.913.134.

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Microstructure analysis of Ni-based superalloy FGH96 under different ageing treatments were carried out in order to understand the microstructure-creep strength relationships of the alloy. It was found that the volume fraction of tertiary γ′ and the mean γ-channel width was significantly varied with different ageing treatments, leading to the changes in creep behavior. The dislocation/γ′ shearing mechanisms were also changed with ageing treatment. The volume fractions of both secondary and tertiary γ′ and the mean γ-channel width were quantitatively analyzed by electron microscopy. The quantified microstructures were used for a crystal plasticity-based constitutive model. It was observed that the crystal plasticity model can accurately simulate experimentally observed creep behavior of aged samples showing significant secondary creep stage.

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Wang, Xiao-Yan, Meng Li et Zhi-Xun Wen. « The Effect of the Cooling Rates on the Microstructure and High-Temperature Mechanical Properties of a Nickel-Based Single Crystal Superalloy ». Materials 13, n^o 19 (24 septembre 2020) : 4256. http://dx.doi.org/10.3390/ma13194256.

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The as-cast alloy of nickel-based single-crystal superalloy was used as the research object. After four hours of solution treatment at 1315 °C, four cooling rates (water cooling (WC), air cooling (AC) and furnace cooling (FC1/FC2)) were used to reduce the alloy to room temperature. Four different microstructures of nickel-based superalloy material were prepared. A high-temperature tensile test at 980 °C was carried out to study the influence of various rates on the formation of the material’s microstructure and to further obtain the influence of different microstructures on the high-temperature mechanical properties of the materials. The results show that an increase of cooling rate resulted in a larger γ′ phase nucleation rate, formation of a smaller γ′ phase and a greater number. When air cooling was used, the uniformity of the γ′ phase and the coherence relationship between the γ′ phase and the γ phase were the best. At the same time, the test alloy had the best high-temperature tensile properties, and the material showed a certain degree of plasticity. TEM test results showed that the test alloy mainly blocked dislocations from traveling in the material through the strengthening effect of γ′, and that AC had the strongest hindering effect on γ′ dislocation movement.

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Thèses sur le sujet "Microstructures γ-γ'"

Orlacchio, Federico. « Évolution de la microstructure du superalliage à base nickel γ-γ' René 65 au cours de sa mise en forme pour la fabrication de disques de turbine ». Electronic Thesis or Diss., Université Paris sciences et lettres, 2024. http://www.theses.fr/2024UPSLM034.

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Les superalliages à base nickel sont des matériaux métalliques de haute performance offrant d'excellents propriétés mécaniques à hautes températures. Pour cette raison, ils sont largement utilisés dans l'industrie aérospatiale pour les parties les plus chaudes et les plus sollicitées des turboréacteurs. Afin d'augmenter la température de fonctionnement et, en même temps, de réduire la consommation de carburant et les émissions de gaz à effet de serre, le superalliage polycristallin à base nickel γ-γ' René 65 a été choisi pour la fabrication de certains disques de turbine des turboréacteurs de nouvelle génération. Cette famille de superalliages présente, en service comme lors de la mise en forme à chaud, deux phases distinctes, nommées γ, solution solide riche en Ni, et γ', composé intermétallique avec composition stœchiométrique Ni3(Al,Ti). Lors de la mise en forme, les deux phases peuvent évoluer simultanément, avec des cinétiques comparables et différents mécanismes d'interactions possibles tels que l'ancrage de Smith-Zener et la recristallisation en hétéroépitaxie, rendant l'étude des évolutions de microstructures sous-jacentes complexe et ambitieuse. L'objectif principal de ce travail est l'étude des évolutions microstructurales à l'œuvre lors des différentes opérations de forgeage à chaud pour les deux phases, γ et γ', avec une approche principalement expérimentale. Pour y parvenir, un chemin themomécanique avec un traitement thermique subsolvus, suivi d'une compression à chaud et se finalisant par un traitement de mise en solution, a été reproduit en laboratoire. Au cours de ce travail, la cinétique expérimentale de dissolution des précipités γ' ainsi que la cinétique de recristallisation statique de la matrice γ au cours d'un traitement subsolvus ont été déterminées. L'effet sur la recristallisation dynamique des paramètres thermomécaniques, tels que le niveau, la vitesse et la température de déformation, a été étudié en détail dans le domaine subsolvus de l'alliage. L'évolution de la microstructure pendant la mise en solution, i.e en régime de croissance de grains, a été analysée à partir de différentes microstructures initiales. En outre, un modèle de croissance de grain en champ moyen en présence de précipités γ', a été calibré et validé pour l'alliage René 65. Ce travail permet de mieux comprendre le comportement en mise en forme des superalliages à base de nickel γ-γ', dans le domaine subsolvus, c'est-à-dire dans un contexte de forte interaction et de couplage entre la matrice γ et les précipités γ'. En conclusion, les résultats obtenus s'avèrent également industriellement important pour, à l'avenir, optimiser le procédé de forgeage à chaud de cet alliage
Nickel-based superalloys are high-performance metallic materials offering excellent mechanical properties at high temperatures. For this reason, they are widely used in the aerospace industry for the hottest, most highly stressed parts of jet engines. To increase operating temperature and, at the same time, reduce fuel consumption and greenhouse gas emissions, the nickel-based polycrystalline superalloy γ-γ' René 65 has been chosen for the manufacture of certain turbine disks in new-generation turbojet engines. In service and during hot forming, this family of superalloys features two distinct phases: γ, a Ni-rich solid solution, and γ', an intermetallic compound with a stoichiometric Ni3(Al,Ti) composition. During forging, both phases can evolve simultaneously, with comparable kinetics and different possible interaction mechanisms such as Smith-Zener pinning and heteroepitaxial recrystallization, making the study of underlying microstructural evolutions complex and ambitious. The main objective of this work is to study the microstructural evolutions at work during the various hot forging operations for the two phases, γ and γ', using a mainly experimental approach. To achieve this, a themomechanical path with subsolvus heat treatment, followed by hot compression and finalized by solution treatment, was reproduced in the laboratory. In the course of this work, the experimental dissolution kinetics of γ' precipitates and the static recrystallization kinetics of the γ matrix during subsolvus treatment were determined. The effect of thermomechanical parameters such as deformation level, strain rate and temperature on dynamic recrystallization has been studied in detail in the subsolvus domain of the alloy. The evolution of the microstructure during solution treatment, i.e. in the grain growth regime, was analyzed from different initial microstructures. In addition, a mean-field grain growth model in the presence of γ' precipitates was calibrated and validated for the René 65 alloy. This work provides a better understanding of the forging behavior of nickel-based γ-γ' superalloys in the subsolvus domain, i.e. in a context of strong interaction and coupling between the γ matrix and γ' precipitates. In conclusion, the results obtained are also industrially important for future optimization of the hot-forging process for this alloy

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Wiezorek, J. M. K. « A TEM study of defect microstructures in the intermetallic titanium aluminides γ-TiAl and α2-Ti-3Al ». Thesis, University of Cambridge, 1994. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.309707.

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Charpentier, Matthias. « Hétérogénéités héritées de la solidification et formation des microstructures dans l'alliage Ti-48Al-2Cr-2Nb : Contribution au développement des alliages intermétalliques de base γ-TiAl ». Vandoeuvre-les-Nancy, INPL, 2003. http://docnum.univ-lorraine.fr/public/INPL_T_2003_CHARPENTIER_M.pdf.

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Cette étude s'inscrit dans le cadre du contrat de programme de recherche "intermétalliques de base titane", qui vise à développer les alliages de base TiAl en vue d'applications structurales dans les moteurs aéronautiques. Ses objectifs ont été de préciser la mise en place des ségrégations chimiques au cours de la solidification et d'étudier l'influence des paramètres de traitements thermiques sur les caractéristiques microstructurales de l'alliage Ti-48Al-2Cr-2Nb élaboré par fonderie et par métallurgie des poudres. Au cours de la solidification, l'aluminium et le chrome sont ségrégés préférentiellement dans les espaces interdendritiques, alors que le titane et le niobium enrichissent la phase solide. La microségrégation du chrome favorise la formation de la phase B2. Lors de traitements à l'état solide, la vitesse de refroidissement contrôle largement le déclenchement de la transformation [indice] α→α[indice]2+γ, le développement de la structure lamellaire α[indice]2-γ et la résistance de l'alliage étudié.

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Ghighi, Julien. « Modélisation du fluage des superalliages monocristallins : effets d'anisotropie et de microstructure ». Phd thesis, ISAE-ENSMA Ecole Nationale Supérieure de Mécanique et d'Aérotechique - Poitiers, 2013. http://tel.archives-ouvertes.fr/tel-00823045.

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La tenue au fluage des aubes de turbine haute pression est une problématique de premier ordre vis-à-visde la certification d'un turbomoteur d'hélicoptère. Les excellentes propriétés mécaniques à hautes températuresdes superalliages monocristallins base nickel en font les matériaux les plus utilisés pour la fabrication de cesaubes. Pour ces composants, les exigences réglementaires de certification imposent la réalisation d'essaisanisothermes, plus sévères que les conditions de fonctionnement en service, basés sur le mixage de différentsrégimes de fonctionnement d'un hélicoptère.L'enjeu de cette thèse est de mieux prédire le comportement mécanique et la durée de vie de cesmatériaux lors d'essais de certification des moteurs d'hélicoptères présentant des endommagementsprépondérants de type fluage grâce à l'établissement d'un modèle de comportement et d'endommagement. Cemodèle doit intégrer les effets transitoires de comportement mécanique et les effets d'anisotropie ; il doit êtreprédictif en termes de durée de vie et doit être apte à modéliser de manière satisfaisante les allongementsrencontrés lors de chargements complexes.Le premier objectif a été d'étudier l'impact de l'anisotropie cristalline sur les propriétés en fluageisotherme, puis son impact en conditions de fluage anisotherme à haute température.Le second objectif fut la formulation d'une modélisation mécanique du comportement en fluage sous trajets dechargements complexes à l'aide du modèle POLYSTAR, modèle de plasticité cristalline couplécomportement/endommagement et enrichi de nouvelles variables internes représentant explicitement lesévolutions rapides de microstructure.

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Le, Graverend Jean-Briac. « Etude et modélisation des effets d'incursion à très haute température sur le comportement mécanique d'un superalliage monocristallin pour aubes de turbine ». Phd thesis, ISAE-ENSMA Ecole Nationale Supérieure de Mécanique et d'Aérotechique - Poitiers, 2013. http://tel.archives-ouvertes.fr/tel-00834830.

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Ce travail s'inscrit dans le contexte de la modélisation et de la prévision de la durée de vie des aubes de turbine haute pression des turbines à gaz. Ces pièces sont réalisées en superalliage monocristallin base nickel tel que le MC2, matériau principal de l'étude. En service, ces dernières sont soumises à des conditions extrêmes de température et de contrainte. Des régimes d'urgence, dits O.E.I. (.One Engine Inoperative.), peuvent aussi survenir sur un hélicoptère bi-moteur : un des deux moteurs s'arrête ce qui provoque une augmentation de la température en sortie de chambre de combustion pour le moteur restant en fonctionnement. Dans le cadre de ce travail, le comportement anisotherme en fluage et en fatigue/fluage du superalliage monocristallin a été étudié afin de déterminer les répercussions des surchauffes à 1200. sur le comportement mécanique ultérieur à 1050. Il a pu être déterminé que le temps de pré-endommagement avant la surchauffe joue un rôle capital vis-à-vis de la durée de vie post-surchauffe. Cette influence est très dépendante de l'état microstructural du matériau sur lequel est réalisée la surchauffe (morphologie des précipités γ ', contraintes de cohérence entre les phases γ et γ '). Du point de vue des mécanismes d'endommagement, il a aussi été constaté que le niveau de température a une importance majeure en modifiant les contraintes de cohérence entre les deux phases γ et γ '. L'état microstructural jouant un rôle majeur sur la durée de vie lors des essais isothermes et anisothermes, une étude de l'évolution de la microstructure γ /γ' autour des particules de phase intermétallique μ a été faite, ainsi qu'une mesure expérimentale de l'évolution de la porosité, mesurée par des analyses tomographiques grâce à des essais de fluage multi-interrompus à haute température. Ceci a permis d'aboutir à un paramètre de dommage, à la frontière entre métallurgie et mécanique, prenant en compte les évolutions microstructurales. La coalescence orientée se déroulant à haute température, connue sous le nom de mise en radeaux, a une forte influence sur le comportement et l'endommagement des superalliages monocristallins. Ainsi, un nouveau modèle de mise en radeaux, prenant en compte la vitesse de sollicitation, a été implémenté dans le modèle de plasticité cristalline couplé comportement/endommagement Polystar. Ceci a permis d'améliorer la modélisation des essais longs. D'autres modifications ont été effectuées afin d'améliorer la modélisation lors des essais cycliques et de relaxation. Ce nouveau modèle a été testé et validé sur une éprouvette bi-entaillée générant des champs mécaniques multiaxiaux pendant un essai de fluage complexe anisotherme.

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Giraud, Rémi. « Influence de l'histoire thermique sur les propriétés mécaniques à haute et très haute température du superalliage monocristallin CMSX-4® ». Thesis, Chasseneuil-du-Poitou, Ecole nationale supérieure de mécanique et d'aérotechnique, 2014. http://www.theses.fr/2014ESMA0005.

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Ce mémoire de thèse est consacré à une étude du fluage isotherme et anisotherme à diversniveaux de température et à l’analyse fine des évolutions microstructurales associées à diverschargements thermomécaniques imposés du superalliage monocristallin, CMSX-4®. Cetravail est complété par la validation d’un modèle de comportement mécanique permettantd’intégrer ces évolutions microstructurales (fraction volumique des phases en présence,largeur des couloirs de matrice gamma, ...) pour déterminer la durée de vie du matériau.Parallèlement, le rôle de la microstructure initiale du matériau associée aux traitementsthermiques imposés dans la phase d’élaboration a été étudié. Il a été montré un effet marquéde cette microstructure initiale lors des essais de fluage à basse température (< 900°C), ainsique lors des essais de fluage anisotherme. Une microstructure de précipitation en radeaux detype N a été montrée comme particulièrement néfaste pour la résistance en fluageanisotherme. Enfin, le comportement du CMSX-4® est systématiquement comparé à celuiprécédemment établi dans des conditions similaires sur d’autres superalliages monocristallinspour pales haute pression
This thesis is dedicated to the study of the isothermal and non-isothermal creep behavior in awide temperature range, and to the analysis of the microstructural evolution during differentthermomechanical paths on the superalloy single crystal, CMSX-4®. Moreover, the validationof a mechanical behavior model validation completes this work. This model takes intoaccount the microstructural evolutions (e.g. phase volume fraction, gamma-matrix channelwidth…) to predict the creep life. Additionally, the effect of the initial microstructure fromthe heat treatment has been investigated. It has been shown a strong impact of the as-receivedmicrostructure on the low temperature isothermal creep properties, and during non-isothermalcreep. A N-type rafted microstructure has been shown to be particularly detrimental to thenon-isothermal creep properties. Finally, the behavior of the CMSX-4® has been comparedwith the previous studies realized in the same conditions on other single crystal superalloysfor blades applications

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Holmboe, Michael. « The Bentonite Barrier : Microstructural properties and the influence of γ-radiation ». Doctoral thesis, KTH, Kärnkemi, 2011. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-34048.

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Rajendran, Mohan Kumar [Verfasser], Ingo [Gutachter] Steinbach et Fathollah [Gutachter] Varnik. « γ - γ' microstructure evolution in single crystal (sx) Ni-base superalloys / Mohan Kumar Rajendran ; Gutachter : Ingo Steinbach, Fathollah Varnik ; Fakultät für Maschinenbau ». Bochum : Ruhr-Universität Bochum, 2018. http://d-nb.info/1163451835/34.

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Rajendran, Mohan Kumar [Verfasser], Ingo [Gutachter] Steinbach et Fathollah [Gutachter] Varnik. « γ-γ ' microstructure evolution in single crystal (sx) Ni-base superalloys / Mohan Kumar Rajendran ; Gutachter : Ingo Steinbach, Fathollah Varnik ; Fakultät für Maschinenbau ». Bochum : Ruhr-Universität Bochum, 2018. http://nbn-resolving.de/urn:nbn:de:hbz:294-65923.

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Duval, Samuel. « Développement d'un photomultiplicateur gazeux cryogénique dédié à un télescope Compton au xénon liquide pour l'imagerie médicale ». Phd thesis, Université de Nantes, 2010. http://tel.archives-ouvertes.fr/tel-00594636.

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Une technique d'imagerie innovante reposant sur la localisation tridimensionnelle d'un radioisotope émetteur (bêta, gamma) à l'aide d'un télescope Compton au xénon liquide a été proposée au laboratoire SUBATECH en 2003. Cette technique, appelée imagerie 3 gammas, repose sur l'association d'une caméra à tomographie d'émission de positons pour la reconstruction des deux photons d'annihilation et d'une chambre à projection temporelle au xénon liquide pour la reconstruction du troisième photon. L'interaction de ce dernier avec le xénon liquide induit un signal de scintillation, lu avec un tube photomultiplicateur, qui permet de déclencher l'acquisition du signal d'ionisation, lu avec un MICROMEGAS (MICRO MEsh Gaseous Structure), donnant accès à la mesure de l'énergie et de la position de chaque interaction. Dans le cadre de ce développement, nous proposons une alternative à la lecture du signal de scintillation avec des tubes photomultiplicateurs classiques : un photomultiplicateur gazeux cryogénique de large surface. Ce photodétecteur est doté d'une photocathode réflective solide d'iodure de césium pour la photoconversion des photons UV et de microstructures amplificatrices telles que le THGEM (THick Gaseous Electron Multiplier), le MICROMEGAS et le PIM (Parallel Ionization Multiplier). Il devrait permettre une segmentation virtuelle du volume de xénon liquide afin de réduire l'occupation du télescope. Les premiers résultats obtenus à l'aide d'un premier prototype de petite surface à la température du xénon liquide (173 K) sont présentés.

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Chapitres de livres sur le sujet "Microstructures γ-γ'"

Zhang, D., V. Güther, N. Eberhardt, H. Kestler et H. Clemens. « Control of Fully Lamellar Microstructures in a γ-TiAl Based Alloy ». Dans Intermetallics and Superalloys, 134–39. Weinheim, FRG : Wiley-VCH Verlag GmbH & Co. KGaA, 2006. http://dx.doi.org/10.1002/3527607285.ch23.

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Xuanyuan, Yaodong, Yan Long, Yinbiao Yan et Sen Yang. « The Effect of Aluminum Content on the Microstructures of Single-Phase γ-TiAl-Based Alloy ». Dans Springer Proceedings in Physics, 221–29. Singapore : Springer Singapore, 2019. http://dx.doi.org/10.1007/978-981-13-5944-6_22.

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Chatterjee, A., U. Bolay, U. Sattler et H. Clemens. « Adjustment of Differently Spaced Fully Lamellar Microstructures in a γ-TiAl Based Alloy and their Creep Behaviour ». Dans Intermetallics and Superalloys, 233–39. Weinheim, FRG : Wiley-VCH Verlag GmbH & Co. KGaA, 2006. http://dx.doi.org/10.1002/3527607285.ch40.

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Sawaguchi, Takahiro. « Designing High-Mn Steels ». Dans The Plaston Concept, 237–57. Singapore : Springer Nature Singapore, 2022. http://dx.doi.org/10.1007/978-981-16-7715-1_11.

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AbstractHigh-Mn austenitic steels undergo characteristic plasticity mechanisms of the γ-austenite with an FCC structure, such as extended dislocation glide, mechanical twinning, and mechanical martensitic transformation into ε-martensite with an HCP structure and/or α’-martensite with a BCC/BCT structure. Distortions of polyhedron models are used to describe these plasticity mechanisms. These are the smallest volumetric units occupying the lattices and reflect the crystallographic characteristics of the lattices. The complicated crossing shears are correlated to the fine crystal phases formed at the intersection of the ε-martensite variants. The unidirectionality of the {1 1 1} < 1 1 2 > γ twinning shear provides reversibility to the dislocation motion under cyclic loading. Based on this knowledge, the design concept of high-Mn steels is described considering microstructural, thermodynamic, and crystallographic characteristics.

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Xie, Mengtao, Randolph C. Helmink et Sammy Tin. « Polycrystalline γ(Ni)/γ′ (Ni3A1)-δ(Ni3Nb) Eutectic Ni-Base Superalloys : Chemistry, Solidification and Microstructure ». Dans Superalloys 2012, 633–42. Hoboken, NJ, USA : John Wiley & Sons, Inc., 2012. http://dx.doi.org/10.1002/9781118516430.ch71.

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Seo, Dong Yi, H. Saari, Peter Au et J. Beddoes. « Microstructure and Creep of γ-TiAl Containing β-Stabilizer ». Dans THERMEC 2006, 1543–48. Stafa : Trans Tech Publications Ltd., 2007. http://dx.doi.org/10.4028/0-87849-428-6.1543.

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Tanaka, Katsushi, et Haruyuki Inui. « Microstructural Change of Monocrystalline Co-Al-W-based γ/γ′ Two Phase Alloys by High Temperature Creep ». Dans PRICM, 409–14. Hoboken, NJ, USA : John Wiley & Sons, Inc., 2013. http://dx.doi.org/10.1002/9781118792148.ch49.

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Tanaka, Katsushi, et Haruyuki Inui. « Microstructural change of monocrystalline Co-Al-W-based γ/γ′ two phase alloys by high temperature creep ». Dans Proceedings of the 8th Pacific Rim International Congress on Advanced Materials and Processing, 409–14. Cham : Springer International Publishing, 2013. http://dx.doi.org/10.1007/978-3-319-48764-9_49.

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Zhang, Beijiang, Guangpu Zhao, Wenyun Zhang, Guohua Xu, Guohua Xu, Heyong Qin et Heyong Qin. « Deformation Mechanisms and Microstructural Evolution of γ + γ′ Duplex Aggregates Generated During Thermomechanical Processing of Nickel-Base Superalloys ». Dans Superalloys 2016, 487–96. Hoboken, NJ, USA : John Wiley & Sons, Inc., 2016. http://dx.doi.org/10.1002/9781119075646.ch52.

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Bauer, Alexander, Steffen Neumeier, Florian Pyczak et Mathias Göken. « Creep Strength and Microstructure of Polycrystalline γ′ - Strengthened Cobalt-Base Superalloys ». Dans Superalloys 2012, 695–703. Hoboken, NJ, USA : John Wiley & Sons, Inc., 2012. http://dx.doi.org/10.1002/9781118516430.ch77.

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Actes de conférences sur le sujet "Microstructures γ-γ'"

Okazaki, Masakazu, et Motoki Sakaguchi. « Prediction of In-Service Stress States of Single Crystal Superalloys Based on Mathematical Analyses of γ/γ' Microstructural Morphologies ». Dans AM-EPRI 2007, sous la direction de R. Viswanathan, D. Gandy et K. Coleman, 783–89. ASM International, 2007. https://doi.org/10.31399/asm.cp.am-epri-2007p0783.

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Abstract The morphology of γ/γ' microstructures in single crystal superalloys is known to evolve during service conditions according to established materials science principles, potentially offering a novel approach for failure analysis. This study investigated the morphological changes in γ/γ' microstructures of CMSX-4, a single crystal Ni-base superalloy, under various loading conditions. The experimental parameters included tensile and compressive stress levels, loading temperature, loading rate, monotonic versus cyclic loading, and multi-axial stress states. Results demonstrated that the γ/γ' microstructures exhibited highly sensitive responses to these loading conditions. A newly developed quantitative image analysis method was used to characterize these morphological changes, and the findings were compiled into a two-dimensional map to facilitate failure analysis and other engineering applications.

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Mehl, Sophie, Anna Cole, Tanner Olson, Paul Sanders, John Shingledecker et Shutong Zhang. « Nickel Superalloy Composition and Process Optimization for Weldability, Cost, and Strength ». Dans AM-EPRI 2024, 699–711. ASM International, 2024. http://dx.doi.org/10.31399/asm.cp.am-epri-2024p0699.

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Abstract Advanced power generation systems, including advanced ultrasupercritical (A-USC) steam and supercritical carbon dioxide (sCO2) plants operating above 700°C, are crucial for reducing carbon dioxide emissions through improved efficiency. While nickel superalloys meet these extreme operating conditions, their high cost and poor weldability present significant challenges. This study employs integrated computational materials engineering (ICME) strategies, combining computational thermodynamics and kinetics with multi-objective Bayesian optimization (MOBO), to develop improved nickel superalloy compositions. The novel approach focuses on utilizing Ni3Ti (η) phase strengthening instead of conventional Ni3(Ti,Al) (γ’) strengthening to enhance weldability and reduce costs while maintaining high-temperature creep strength. Three optimized compositions were produced and experimentally evaluated through casting, forging, and rolling processes, with their microstructures and mechanical properties compared to industry standards Nimonic 263, Waspaloy, and 740H. Weldability assessment included solidification cracking and stress relaxation cracking tests, while hot hardness measurements provided strength screening. The study evaluates both the effectiveness of the ICME design methodology and the practical potential of these cost-effective η-phase strengthened alloys as replacements for traditional nickel superalloys in advanced energy applications.

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Kumar, N. Naveen, Sonali Ravikumar, Boateng Twum Donkor, Jie Song, Vishal Soni, Abhishek Sharma, Sriswaroop Dasari et al. « Investigation of Novel Nickel-Based Alloys for High Temperature Molten Chloride Salt Reactor Structural Applications ». Dans AM-EPRI 2024, 1126–37. ASM International, 2024. http://dx.doi.org/10.31399/asm.cp.am-epri-2024p1126.

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Abstract An attempt is being made to develop novel Ni-Mo-W-Cr-Al-X alloys with ICME approach with critical experimental/simulations and processing/microstructural characterization/property evaluation and performance testing has been adopted. In this work, based on thermodynamic modeling five alloy compositions with varying Mo/W and two alloys with high tungsten modified with the addition of Al or Ti were selected and prepared. The newly developed alloys were evaluated for their response to thermal aging in the temperature range of 700 to 850 °C and corrosion in the KCl-NaCl-MgCl2 salt under suitable conditions. Thermally aged and post-corrosion test samples were characterized to ascertain phase transformations, microstructural changes and corrosion mechanisms. Al/Ti modified alloys showed significant change in hardness after 400 hours aging at 750°C, which was found to be due to the presence of fine γ’/γ” precipitates along with plate-shaped W/Mo-rich particles. These alloys show comparable molten salt corrosion resistance as commercial alloys at 750°C for 200-hour exposures. The good corrosion behavior of these alloys may be attributed to the formation of a protective multicomponent Al-or Ti-enriched oxide as well as the unique microstructure.

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Imano, Shinya, Jun Sato, Koji Kajikawa et Tatsuya Takahashi. « Mechanical Properties and Manufacturability of Ni-Fe Base Superalloy (FENIX-700) for A-USC Steam Turbine Rotor Large Forgings ». Dans AM-EPRI 2007, sous la direction de R. Viswanathan, D. Gandy et K. Coleman, 424–33. ASM International, 2007. https://doi.org/10.31399/asm.cp.am-epri-2007p0424.

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Abstract To develop 10-ton class forgings with adequate long-term strength and without segregation defects for A-USC steam turbine rotors, researchers modified the chemical composition of Alloy 706 to improve its microstructure stability and segregation properties. The modified Alloy, named FENIX-700, is a γ' phase strengthened alloy without a γ" phase, and its microstructure stability is superior to Alloy 706 at 700°C, as demonstrated by short-term aging tests and phase stability calculations using the CALPHAD method. A trial disk 1-ton class forging of FENIX-700 was manufactured from a double-melted ingot, with tensile and creep strength of the forging equivalent to that of 10-kg class forgings, indicating a successful trial. Long-duration creep tests were performed using 10-kg class forgings, revealing an approximate 105-hour creep strength at 700°C higher than 100 MPa. Manufacturability tests showed that FENIX-700 performs better than Alloy 706, as evidenced by segregation tests using a horizontal directional solidification furnace and hot workability tests. Microstructure observation and tensile tests on 10,000-hour aged specimens (at temperatures of 650, 700, and 750°C) revealed degradation of tensile strength and yield stress due to coarsening of the γ' phase, but also showed enhanced ductility through aging. The microstructure stability of FENIX-700 at 700°C was confirmed as excellent through microstructure observation of the 10,000-hour aged sample and supporting thermodynamic considerations.

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Kobayashi, Satoru, et Takumi Tsuya. « Creep Behaviors of Alloy 718 Type Ni-Based Superalloys ». Dans AM-EPRI 2024, 441–48. ASM International, 2024. http://dx.doi.org/10.31399/asm.cp.am-epri-2024p0441.

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Abstract Alloy 718 is an important class of Nb-bearing Ni-based superalloys for high-temperature applications, such as compressor disks/blades and turbine disks in gas turbine systems. The service temperature of this alloy is, however, limited below 650 °C probably due to the degradation of its strengthening phase γ"-Ni3Nb. Aiming at understanding and improving creep properties of 718-type alloys, we investigated creep behaviors of alloy 718 and alloy Ta-718 where different types of γ" phases, Ni3Nb and Ni3Ta, were precipitated, respectively. Creep tests were conducted at 700 °C under stress conditions of 400 and 500 MPa for the two alloys in aged conditions. It was found that while the minimum creep rates were comparable in the two alloys, the creep rate acceleration was lower in alloy Ta-718 than in alloy 718 under the creep conditions studied. Microstructural observations on the specimens before and after the creep tests suggested that the γ" precipitates were distinguishably finer in alloy Ta-718 than in alloy 718 throughout the creep tests. The formation of planar defects and shearing of γ" precipitates occurred frequently in the alloy 718 specimen. The observed creep deformations were discussed in terms of the critical resolved shear stress due to shearing of γ" particles by strongly paired dislocations.

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Dryepondt, Sebastien, Holden Hyer, Fred List, Stephen Taller, Amir Ziabari, Yi-Feng Su et Zackary Snow. « Microstructure and Mechanical Properties of Ni-based Alloys Fabricated by Laser Powder Bed Fusion ». Dans AM-EPRI 2024, 159–70. ASM International, 2024. http://dx.doi.org/10.31399/asm.cp.am-epri-2024p0159.

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Abstract The Advanced Materials and Manufacturing Technologies (AMMT) program is aiming at the accelerated incorporation of new materials and manufacturing technologies into nuclear-related systems. Complex Ni-based components fabricated by laser powder bed fusion (LPBF) could enable operating temperatures at T > 700°C in aggressive environments such as molten salts or liquid metals. However, available mechanical properties data relevant to material qualification remains limited, in particular for Ni-based alloys routinely fabricated by LPBF such as IN718 (Ni- 19Cr-18Fe-5Nb-3Mo) and Haynes 282 (Ni-20Cr-10Co-8.5Mo-2.1Ti-1.5Al). Creep testing was conducted on LPBF 718 at 600°C and 650°C and on LPBF 282 at 750°C. finding that the creep strength of the two alloys was close to that of wrought counterparts. with lower ductility at rupture. Heat treatments were tailored to the LPBF-specific microstructure to achieve grain recrystallization and form strengthening γ' precipitates for LPBF 282 and γ' and γ" precipitates for LPBF 718. In-situ data generated during printing and ex-situ X-ray computed tomography (XCT) scans were used to correlate the creep properties of LPBF 282 to the material flaw distribution. In- situ data revealed that spatter particles are the potential causes for flaws formation in LPBF 282. with significant variation between rods based on their location on the build plate. XCT scans revealed the formation of a larger number of creep flaws after testing in the specimens with a higher initial flaw density. which led to a lower ductility for the specimen.

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Guangyuan, Shi, Wang Yinghao, Mu Yuyang, Wang Wuyang, Zhang Yuntao et Cui Minchao. « Microstructure classification of γ-TiAl alloy using an MLP deep learning analysis model of LIBS spectra ». Dans Optical Spectroscopy and Applications, sous la direction de Zongyin Yang, 1. SPIE, 2024. https://doi.org/10.1117/12.3045540.

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Antonov, S., M. Detrois et S. Tin. « Precipitate Phase Stability and Compositional Dependence on Alloying Additions in Advanced Ni-Base Superalloys ». Dans AM-EPRI 2016, sous la direction de J. Parker, J. Shingledecker et J. Siefert. ASM International, 2016. http://dx.doi.org/10.31399/asm.cp.am-epri-2016p0213.

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Abstract Modern polycrystalline Ni-base superalloys for advanced gas turbine engines have been a key component that has contributed to technological advances in propulsion and power generation. As advanced turbine engine designs are beginning to necessitate the use of materials with temperature and strength capabilities beyond those exhibited by existing materials, new alloying concepts are required to replace conventional Ni-base superalloys with conventional γ-γ’ microstructures. The phase stability of various high Nb content Ni-base superalloys exhibiting γ-γ’-δ -η microstructures have been the subject of a number of recent investigations due to their promising physical and mechanical properties at elevated temperatures. Although high overall alloying levels of Nb, Ta and Ti are desirable for promoting high temperature strength in γ-γ’ Ni-base superalloys, excessive levels of these elements induce the formation of δ and η phases. The morphology, formation, and composition of precipitate phases in a number of experimental alloys spanning a broad range of compositions were explored to devise compositional relationships that can be used to predict the microstructural phase stability and facilitate the design of Ni-base superalloys.

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Wakabayashi, Hideki, Ryosuke Yamagata, Hirotoyo Nakashima et Masao Takeyama. « Effects of γ-TiAl/γ Lamellar Interfaces and Grain-Boundary α2-Ti3Al Phase on Creep of TiAl Based Alloy ». Dans AM-EPRI 2019, sous la direction de J. Shingledecker et M. Takeyama. ASM International, 2019. http://dx.doi.org/10.31399/asm.cp.am-epri-2019p1395.

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Abstract The creep behavior of a γ-TiAl based alloy at 1073 K was investigated, examining three different microstructures: equiaxed γ (Eγ), γ/γ fully lamellar (FLγ), and equiaxed γ with α2 phase on grain boundaries (Eγα2). The aim was to understand the influence of lamellar interfaces and grain boundary α2 phase on creep behavior. Initially, creep rates were consistent across all specimens upon loading. However, Eγ exhibited a gradual decrease in creep rate compared to Eγα2 and FLγ. Notably, the minimum creep rate of Eγ was one order of magnitude lower than that of Eγα2 and FLγ. Conversely, Eγα2 and FLγ displayed a slight acceleration and the longest rupture strain, albeit with the shortest rupture time compared to Eγ. Upon microstructural analysis of of the creep-test specimens, it was observed that numerous dynamic recrystallized grains (DXGs) and sub-grains formed along grain boundaries and interiors in Eγ, whereas they were limited to the region along grain boundaries in FLγ. In contrast, very few DXGs were formed in Eγα2. These findings indicate that γ/γ interfaces inhibit the extension of DXGs into grain interiors, suggesting that the grain boundary α2 phase effectively suppresses the formation of DXGs.

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Gong, Xibing, Xiaoqing Wang, Vernon Cole, Zachary Jones, Kenneth Cooper et Kevin Chou. « Characterization of Microstructure and Mechanical Property of Inconel 718 From Selective Laser Melting ». Dans ASME 2015 International Manufacturing Science and Engineering Conference. American Society of Mechanical Engineers, 2015. http://dx.doi.org/10.1115/msec2015-9317.

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In this study, the microstructures and mechanical properties of Inconel 718 fabricated from selective laser melting (SLM) process were experimentally investigated. Specimens with different build heights were prepared for microstructural observations by optical microscopy and scanning electron microscope. The texture evolution was also examined using electron backscatter diffraction (EBSD). In general, columnar γ dendrites are found along the build direction from the X-plane (side surface), while the microstructure of Z-plane (scanning surface) is characterized by equiaxed grains. The microstructures vary along the build height: the top layers present coarse columnar dendrites while the bottom layers show much narrower columnar dendrites owing to a higher cooling rate. The top layers also present the combination of a γ matrix and a higher percentage of the Laves phase, while the bottom layers show a much less Laves phase due to, again, a higher cooling rate. Random textures are shown for the SLM Inconel 718 samples. Nanoindentation tests identify the Young’s modulus and hardness of about 200 GPa and 7 GPa, respectivley.

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