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Smith, Andrew Logan Mr. "Thermodynamic Evaluation and Modeling of Grade 91 Alloy and its Secondary Phases through CALPHAD Approach." FIU Digital Commons, 2018. https://digitalcommons.fiu.edu/etd/3773.
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Grade 91 (Gr.91) is a common structural material used in boiler applications and is favored due to its high temperature creep strength and oxidation resistance. Under cyclic stresses, the material will experience creep deformation eventually causing the propagation of type IV cracks within its heat-affected-zone (HAZ) which can be a major problem under short-term and long-term applications. In this study, we aim to improve this premature failure by performing a computational thermodynamic study through the Calculation of Phase Diagram (CALPHAD) approach. Under this approach, we have provided a baseline study as well as simulations based on additional alloying elements such as manganese (Mn), nickel (Ni), and titanium (Ti). Our simulation results have concluded that high concentrations of Mn and Ni had destabilized M23C6 for short-term creep failure, while Ti had increased the beneficial MX phase, and low concentrations of nitrogen (N) had successfully destabilized Z-phase formation for long-term creep failure.
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Di, Napoli Paolo. "Modélisation des évolutions microstructurales par changement de phases dans les alliages de titane [bêta] - métastables." Thesis, Vandoeuvre-les-Nancy, INPL, 2010. http://www.theses.fr/2010INPL070N/document.
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Un modèle a été développé pour prédire les cinétiques de transformation de phase beta → alpha dans les alliages de titane multi constitués au cours de chemins thermiques complexes. Il repose sur : (i) une simplification de la représentation géométrique des différentes morphologies communément observées dans ces alliages (grains parents bêta, phase α(allotriomorphe) aux joints des grains parents, colonies de phase α, précipités α intragranulaires) ; (ii) des lois analytiques de germination et de croissance pour les diverses morphologies de phase α; (iii) l’hypothèse d'équilibre local aux interfaces β/α, décrite par un approche de type CalPhad ; (vi) des bilans moyens de soluté dans chaque morphologie. Nous obtenons ainsi pour chaque morphologie, les cinétiques de transformation, les évolutions de leurs tailles moyennes, et enfin les évolutions de leur composition moyenne. Nous présentons tout d’abord les calculs réalisés pour un alliage ternaire TiVO, afin de montrer les potentialités du modèle. L’analyse des résultats met en avant l’influence respective de la diffusion des solutés dans les deux phases, de la morphologie des précipités formés sur la cinétique de croissance comme sur la composition moyenne des grains formés tant pour une transformation en condition isotherme qu’au cours d’un refroidissement continu ou encore d’une séquence complexe de traitement thermique (refroidissement, chauffage, refroidissement). Le modèle a également été utilisé pour calculer les cinétiques de transformation pour l’alliage industriel Ti17 et ainsi comparer les résultats calculés aux résultats expérimentaux (cinétique et microstructures)A model has been developed which is able to predict the kinetics of beta → alpha transformation in industrial multi component titanium alloys during complex heat treatments. The model is based on: (i) a simple geometric representations of the different morphologies commonly observed in these alloys (parent α grains, α allotriomorphs (at grain boundaries), αcolonies and intragranular α precipitates); (ii) analytical nucleation and growth laws for each morphology of α phase; (iii) the assumption of local equilibrium at interfaces, handled within the CalPhaD framework; (iv) averaged solute balances in each morphology. Diffusion of solutes in both phases is considered. We thus obtain the transformation kinetics as well as mean size parameters and mean chemical composition for each morphology of the product α phase (at grain boundaries, colonies and intragranular precipitates. Calculations performed are at first presented for a ternary TiVO alloy emphasizing the potentialities of the model. The relationships between growth conditions, role of diffusion in each phase, and chemical composition for each morphology are analyzed upon isothermal holdings, cooling from the beta phase field and more complex cooling-heating sequence. The model is further used on the Ti17 industrial and results are compared to experimental transformation kinetics and microstructures
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Ricciardi, Denielle E. "Uncertainty Quantification and Propagation in Materials Modeling Using a Bayesian Inferential Framework." The Ohio State University, 2020. http://rave.ohiolink.edu/etdc/view?acc_num=osu1587473424147276.
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Asp, Grönhagen Klara. "Phase-field modeling of surface-energy driven processes." Doctoral thesis, KTH, Metallografi, 2009. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-11036.
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Surface energy plays a major role in many phenomena that are important in technological and industrial processes, for example in wetting, grain growth and sintering. In this thesis, such surface-energy driven processes are studied by means of the phase-field method. The phase-field method is often used to model mesoscale microstructural evolution in materials. It is a diffuse interface method, i.e., it considers the surface or phase boundary between two bulk phases to have a non-zero width with a gradual variation in physical properties such as energy density, composition and crystalline structure. Neck formation and coarsening are two important diffusion-controlled features in solid-state sintering and are studied using our multiphase phase-field method. Inclusion of Navier-Stokes equation with surface-tension forces and convective phase-field equations into the model, enables simulation of reactive wetting and liquid-phase sintering. Analysis of a spreading liquid on a surface is investigated and is shown to follow the dynamics of a known hydrodynamic theory. Analysis of important capillary phenomena with wetting and motion of two particles connected by a liquid bridge are studied in view of important parameters such as contact angles and volume ratios between the liquid and solid particles. The interaction between solute atoms and migrating grain boundaries affects the rate of recrystallization and grain growth. The phenomena is studied using a phase-field method with a concentration dependent double-well potential over the phase boundary. We will show that with a simple phase-field model it is possible to model the dynamics of grain-boundary segregation to a stationary boundary as well as solute drag on a moving boundary. Another important issue in phase-field modeling has been to develop an effective coupling of the phase-field and CALPHAD methods. Such coulping makes use of CALPHAD's thermodynamic information with Gibbs energy function in the phase-field method. With the appropriate thermodynamic and kinetic information from CALPHAD databases, the phase-field method can predict mictrostructural evolution in multicomponent multiphase alloys. A phase-field model coupled with a TQ-interface available from Thermo-Calc is developed to study spinodal decomposition in FeCr, FeCrNi and TiC-ZrC alloys.QC 20100622
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Lu, Xiao-Gang. "Theoretical modeling of molar volume and thermal expansion." Doctoral thesis, Stockholm, 2005. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-252.
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Ucci, Russell. "Investigation of Interface Diffusion on the Reliability of AlGaN/GaN High Electron Mobility Transistor by Thermodynamic Modeling." Miami University / OhioLINK, 2012. http://rave.ohiolink.edu/etdc/view?acc_num=miami1344529070.
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Dalton, John Christian. "Thermodynamics of Paraequilibrium Carburization and Nitridation of Stainless Steels." Case Western Reserve University School of Graduate Studies / OhioLINK, 2014. http://rave.ohiolink.edu/etdc/view?acc_num=case1386586585.
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Lin, Kang-Yi. "The Dissolution of Iron from Automotive Steel Sheets in a Molten Zinc Bath and the Kinetics of the Nucleation and Growth of Dross Particles." Case Western Reserve University School of Graduate Studies / OhioLINK, 2011. http://rave.ohiolink.edu/etdc/view?acc_num=case1307733545.
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Paulus, Kyle. "Combined CALPHAD and Machine Learning for Property Modelling." Thesis, KTH, Materialvetenskap, 2020. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-278149.
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Techniques to improve the speed at which materials are researched and developed has been conducted by investigating the machine learning methodology. These techniques offer solutions to connect the length scales of material prop- erties from atomistic and chemical features using materials databases generated from collected data. In this assessment, two material informatics methodologies are used to predict material properties in steels and nickel based superalloys using this approach. Martensite start temperature and sigma phase amount as a function of input composition has been modelled with the use of machine learning algorithms. The experimental methodology had a collection of over 2000 unique experimental martensite start temperature points. This yielded important information on higher order interactions for the martensite start temperature, and a root mean square error (rmse) of 29 Kelvin using ensemble tree based algorithms. The metamodel was designed using an artificial neural network from TensorFlow’s library to predict sigma phase fraction and its composition. The methodology for building, calculating, and using data from TC-Python will be laid out. This generates a model that would generalize sigma phase fraction 97.9 % of Thermo-Calc’s equilibrium model in 7.1 seconds compared to 227 hours neded in the simulation to calculate the same amount of material property data.Tekniker för att förbättra hastigheten med material som forskas och utvecklas har genomförts genom att undersöka metodik för maskininlärning. Dessa tekniker erbjuder lösningar för att ansluta längdskalorna för materialegenskaper från atomistiska och kemiska egenskaper med hjälp av materialdatabaser genererade från insamlade data. I denna bedömning används två materialinformatikmetoder för att förutsäga materialegenskaper i stål och nickelbaserade superlegeringar med denna metod. Martensite-starttemperatur och sigmafasmängd som en funktion av ingångssammansättningen har modellerats med användning av maskininlärningsalgoritmer. Den experimentella metoden hade en samling av över 2000 unika experimentella starttemperaturpunkter för martensit. Detta gav viktig information om interaktioner med högre ordning för martensit-starttemperaturen och ett root-medelvärde-kvadratfel (rmse) på 29 Kelvin med användning av ensemble-trädbaserade algoritmer. Metamodellen designades med hjälp av ett artificiellt neuralt nätverk från TensorFlows bibliotek för att förutsäga sigma-fasfraktion och dess sammansättning. Metoden för att bygga, beräkna och använda data från TC-Python kommer att anges. Detta genererar en modell som skulle generalisera sigma-fasfraktion 97,9 % av Thermo-Calcs jämviktsmodell på 7,1 sekunder jämfört med 227 timmar som behövs i simuleringen för att beräkna samma mängd materialegenskapsdata.
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König, Hans-Henrik. "Calphad data handling for generic precipitation modelling coupled with FEM." Thesis, KTH, Materialvetenskap, 2020. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-280039.
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To enable a generic modelling tool for precipitation kinetics in non-homogeneous components, an efficient data-handling is required to facilitate the integration of models on different length scales, and to decrease the computational time and the use of resources. In this work an automated method to generate, curate and transform Calphad- based thermodynamic and kinetic data to facilitate precipitation models integrated in FEM codes is developed and tested. The open-source Python library, pycalphad, is employed to access Calphad databases. Python scripts are utilized to calculate the thermodynamic and kinetic parameters, required to supply a precipitation model. The obtained data is stored with an open-source software infrastructure. The Cu-Co binary is the chosen model alloy in this work and the corre-sponding parameters are calculated and stored. The obtained results show, that pycalphad can be used to supply the required thermodynamic and kinetic pa- rameters for a precipitation model. Further refinement of the presented sourcecode is required to enable application in the whole composition range.För utveckling av ett generiskt modelleringsverktyg för utskiljningskinetiken i inhomogena komponenter krävs en effektiv databehandling som möjliggör integration av modeller för olika längdskalor och minskar beräkningstiden och resursförbrukningen. I denna avhandling utvecklas och testas en automatiserad metod för att generera, kurera och transformera termodynamisk och kinetisk Calphad-data. Detta möjliggör integration av utskiljningsmodeller i finita-element metodkoder. Pycalphad tillsammans med en öppen källkod används för att komma åt Calphad-databaser. Ett Python-skript används för att beräkna de termodynamiska och kinetiska parametrarna som används i utskiljningsmodellen. Uppgifterna sparas i en öppen källkodsinfrastruktur. Den utvecklade metoden demonstreras genom att generera, kurera och transformera information för det binära modellsystemet Cu-Co Resultaten visar att Pycalphad kan användas för att tillhandahålla de nödvändiga termodynamiska och kinetiska parametrarna för utskiljningsmodeller. En ytterligare förbättring av den presenterade källkoden är nödvändig för att möjliggöra applikationen inom hela sammansättningsområdet.
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Dalton, John Christian. "Surface Hardening of Duplex Stainless Steel 2205." Case Western Reserve University School of Graduate Studies / OhioLINK, 2017. http://rave.ohiolink.edu/etdc/view?acc_num=case1480696856644048.
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Yang, Yang. "Investigation of vanadium-containing oxide systems : CALPHAD and experiments." Doctoral thesis, KTH, Termodynamisk modellering, 2016. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-197292.
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Fundamental studies on thermodynamic properties of vanadium-containing oxides systems are essential to understand practical vanadium metallurgical process. The CALPHAD technique is here applied to the thermodynamic modelling of the V-O, Ca-V-O and Ti-V-O systems. The compound energy formalism is used for all the solution phases. All optimization processes and calculations are performed using the Thermo-Calc software package. The present work attempts to develop a self-consistent thermodynamic database of all phases in the studied systems. The obtained datasets can be used to calculate thermodynamic properties, stable as well as metastable phase equilibria and driving forces for oxidation etc. Steelmaking slag is an important secondary source for vanadium extraction. The phase relationships and vanadium distribution in the CaO-SiO2-MgO-V2O3-Al2O3 synthetic slags, whose compositions were chosen based on the relevance to the steel producers, are also studied. Phase equilibria in the temperature range of 1773 to 1823 K at oxygen partial pressure of 10-10 bar and 0.21 bar were characterized. An investigation of the volatilization of vanadium oxide was also carried out in the present work. Isothermal evaporation of vanadium pentoxide in the temperature range between 1723 and 1873 K was investigated by Thermogravimetric Analysis under different oxygen partial pressures, viz. oxygen, air or CO2. The Arrhenius activation energy for the evaporation reaction in various atmospheres was calculated from the experimental results. A mathematical model was developed to describe the kinetics of the evaporation process. Evaporation coefficients and enthalpies in various atmospheres were also estimated. The present results may have some implications in recovering vanadium from different vanadium-bearing sources.QC 20161202
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Cui, Jinjiang. "Approche thermodynamique des interactions chimiques dans les systèmes Zr-Cr-O et U-Cr-O à hautes températures pour l'évaluation des combustibles ATF (Accident Tolerant Fuel) en conditions accidentelles." Electronic Thesis or Diss., Université de Lille (2022-....), 2023. http://www.theses.fr/2023ULILR045.
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Le développement de matériaux combustibles tolérants aux accidents (ATF) est un moyen d'améliorer la sûreté des réacteurs à eau légère. L'alliage de zirconium recouvert de Cr (M5) et le combustible UO2 dopé à l'oxyde de chrome Cr2O3 figurent parmi les solutions à court terme les plus prometteuses. L'objectif de cette thèse était de réaliser une étude expérimentale des relations de phase, des propriétés thermodynamiques des systèmes ternaires Zr-Cr-O et U-Cr-O, et sur cette base expérimentale, de développer une modélisation thermodynamique de ces systèmes qui pourrait aider à évaluer le comportement de ces nouveaux concepts, en particulier à haute températures, conditions qui prévalent en situation d'accidents graves.Pour le système binaire Zr-Cr, les expériences ont d'abord été consacrées à la détermination précise des transformations invariantes (eutectiques et eutectoïde) ; la phase ZrCr2 Laves a été soigneusement étudiée. L'enthalpie de formation de cette phase a été mesurée par calorimétrie de dissolution. Sa capacité thermique spécifique a été mesurée sur un large intervalle de température (1.8K à 1063K). Une modélisation CALPHAD du système prenant en compte les données expérimentales obtenues et des simulations DFT a été réalisée.Pour le système ternaire Zr-Cr-O, les sections isothermes à 1473K et 1773K ont été obtenues. Une méthode de préparation d'échantillons de Zr3Cr3O de haute pureté a été développée. La structure cristalline, l'enthalpie de formation et la capacité thermique spécifique de Zr3Cr3O ont été déterminées. Une modélisation CALPHAD a été faite en combinant ces nouveaux résultats et les modélisations des systèmes Zr-O et Cr-O déjà disponibles dans la base de données NUCLEA.Une modélisation CALPHAD du système binaire U-Cr a été réalisée avec nos nouvelles mesures et les données publiées dans la littérature. Des résultats préliminaires ont été obtenus pour le système ternaire U-Cr-O à 1273K. Des échantillons d'UCrO4 ont été préparés avec une grande pureté et leur capacité thermique à basse température a été mesurée ainsi que leur température de Néel.Tous ces résultats bénéficieront à la base de données thermodynamiques NUCLEA de l'IRSN développée pour les applications liées aux accidents gravesThe development of Accident Tolerant Fuel (ATF) materials is one way to improve the safety of light water reactors. Cr-coated zirconium alloy (M5) and UO2 fuel doped with Cr2O3 chromium oxide are among the most promising short-term solutions. This thesis aimed to perform an experimental study of the phase relations, of thermodynamic properties of the Zr-Cr-O and U-Cr-O ternary systems, and on this experimental basis, to develop thermodynamic modeling of these systems which could help to assess the behavior of these new concepts, in particular at a high temperature which prevail in severe accident conditions.For the Zr-Cr binary system, experiments were firstly devoted to determine with accuracy the invariant transformation (eutectics and eutectoid); the ZrCr2 Laves phase was carefully investigated. The enthalpy of formation of this phase was measured by drop solution calorimetry. The specific heat capacity was measured in a wide temperature interval (1.8K to 1063K). A CALPHAD modeling of the system taking into account the obtained experimental data and DFT simulations was performed.For the Zr-Cr-O ternary system, the isothermal sections at 1473K and 1773K were obtained. A method to prepare Zr3Cr3O samples with high purity was developed. The crystal structure, enthalpy of formation and specific heat capacity of Zr3Cr3O were measured. A CALPHAD assessment was made by combining these new results and the modeling of Zr-O and Cr-O systems already present in the NUCLEA database.A CALPHAD modeling of the U-Cr binary system was realized with our new measurements and published data in the literature. Some preliminary results were obtained for the U-Cr-O ternary system at 1273K. UCrO4 samples were prepared with high purity and its heat capacity at low temperatures was measured as well as its Néel temperature.All these results would benefit the thermodynamic NUCLEA database of IRSN developed for severe accident applications
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Palanivel, Sivanesh. "Thermomechanical Processing, Additive Manufacturing and Alloy Design of High Strength Mg Alloys." Thesis, University of North Texas, 2016. https://digital.library.unt.edu/ark:/67531/metadc849628/.
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The recent emphasis on magnesium alloys can be appreciated by following the research push from several agencies, universities and editorial efforts. With a density equal to two-thirds of Al and one-thirds of steel, Mg provides the best opportunity for lightweighting of metallic components. However, one key bottleneck restricting its insertion into industrial applications is low strength values. In this respect, Mg-Y-Nd alloys have been promising due to their ability to form strengthening precipitates on the prismatic plane. However, if the strength is compared to Al alloys, these alloys are not attractive. The primary reason for low structural performance in Mg is related to low alloying and microstructural efficiency. In this dissertation, these terminologies are discussed in detail. A simple calculation showed that the microstructural efficiency in Mg-4Y-3Nd alloy is 30% of its maximum potential. Guided by the definitions of alloying and microstructural efficiency, the two prime objectives of this thesis were to: (i) to use thermomechanical processing routes to tailor the microstructure and achieve high strength in an Mg-4Y-3Nd alloy, and (ii) optimize the alloy chemistry of the Mg-rare earth alloy and design a novel rare—earth free Mg alloy by Calphad approach to achieve a strength of 500 MPa.
Experimental, theoretical and computational approaches have been used to establish the process-structure-property relationships in an Mg-4Y-3Nd alloy. For example, increase in strength was observed after post aging of the friction stir processed/additive manufactured microstructure. This was attributed to the dissolution of Mg2Y particles which increased the alloying and microstructural efficiency. Further quantification by numerical modeling showed that the effective diffusivity during friction stir processing and friction stir welding is 60 times faster than in the absence of concurrent deformation leading to the dissolution of thermally stable particles. In addition, the investigation on the interaction between dislocations and strengthening precipitate revealed that, specific defects like the I1 fault aid in the accelerated precipitation of the strengthening precipitate in an Mg-4Y-3Nd alloy. Also, the effect of external field (ultrasonic waves) was studied in detail and showed accelerated age hardening response in Mg-4Y-3Nd alloy by a factor of 24.
As the bottleneck of low strength is addressed, the answers to the following questions are discussed in this dissertation: What are the fundamental micro-mechanisms governing second phase evolution in an Mg-4Y-3Nd alloy? What is the mechanical response of different microstructural states obtained by hot rolling, friction stir processing and friction stir additive manufacturing? Is defect engineering critical to achieve high strength Mg alloys? Can application of an external field influence the age hardening response in an Mg-4Y-3Nd alloy? Can a combination of innovative processing for tailoring microstructures and computational alloy design lead to new and effective paths for application of magnesium alloys?
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Cardon, Clément. "Modélisation de la diffusion multi-composants dans un bain de corium diphasique oxyde-métal par une méthode d'interface diffuse." Thesis, Université Paris-Saclay (ComUE), 2016. http://www.theses.fr/2016SACLX096/document.
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Ce travail de thèse porte sur la modélisation de la cinétique de stratification des phases liquides oxyde et métallique dans un bain de corium (système U-O-Zr-acier) du point de vue de la diffusion multi-composants et multiphasique. Cette démarche de recherche s’inscrit dans le cadre du développement d’une modélisation « fine » du comportement d’un bain de corium basée sur une approche CFD (« Computational Fluid Dynamics ») de la thermo-hydraulique. Elle vise à améliorer la compréhension des phénomènes mis en jeu et construire des lois de fermetures adéquates pour des modèles macroscopiques intégraux.Pour ce faire, la méthode du champ de phase couplée avec une fonctionnelle d’énergie utilisant la méthode CALPHAD se révèle être un outil pertinent.Dans une première partie, nous nous sommes intéressés au système binaire U-O. Nous avons développé un modèle à interface diffuse (basé sur une équation de Cahn-Hilliard) pour décrire la diffusion dans ce système. Nous avons procédé à la mise en place du couplage entre ce modèle et une base de données thermodynamiques CALPHAD, ainsi qu’au paramétrage d’un tel modèle avec en particulier une procédure d’élargissement de l’interface.Ensuite, dans le cadre d’une modélisation sur le système ternaire U-O-Zr nous avons proposé une généralisation du modèle à interface diffuse par le biais d’une hypothèse d’équilibre local des mécanismes d’oxydo-réduction. Nous avons porté une attention particulière à l’analyse de ce modèle par le biais de simulations numériques 1D en nous intéressant notamment à l’état stationnaire et aux profils de composition obtenus.Finalement, nous avons montré l’application de ce modèle au système U-O-Zr-Fe. Pour cela, nous avons considéré une configuration similaire aux essais expérimentaux à « petite échelle » relatifs à l’étude de la stratification d’un bain oxyde-métalThis Ph.D. topic is focused on the modelling of stratification kinetics for an oxide-metal corium pool (U-O-Zr-steel system) in terms of multicomponent and multiphase diffusion. This work is part of a larger research effort for the development of a detailed corium pool modelling based on a CFD approach (“Computational Fluid Dynamics”) for thermal-hydraulics. The overall goal is to improve the understanding of the involved phenomena and obtain closure laws for integral macroscopic models.The phase-field method coupled with an energy functional using the CALPHAD method appears to be relevant for this purpose.In a first part, this works has been focused on the U-O binary system. We have developed a diffuse interface model (based on a Cahn-Hilliard equation) in order to describe the diffusion process in this system. This model has been coupled with a CALPHAD thermodynamic database and its parameterization has been developed with, in particular, an upscaling procedure related to the interface thickness.Then, within the framework of a modelling for the U-O-Zr ternary system, we have proposed a generalization of the diffuse interface model through an assumption of local equilibrium for redox mechanisms. A particular attention was paid to the model analysis by 1D numerical simulations with a special focus on the steady state composition profiles.Finally we have applied this model to the U-O-Zr-Fe system. For that purpose, we have considered a configuration close to small-scale experimental tests dedicated to the study of oxide-metal corium pool stratification
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Kumpati, Joshva. "Thermodynamic Modelling and Experimental Investigation of Tungsten Partitioning in Nickel Based Alloys." Thesis, KTH, Materialvetenskap, 2018. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-235643.
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Thermo-Calc software AB develops high quality thermodynamic and kinetic databases to predict and simulate accurately multi-component phase behaviour in complex systems. One problem with their Ni-based alloys and superalloy solutions database (TCNI8) is poor description of tungsten partitioning for multi-component nickel based alloys. This work investigates the thermodynamic description of some lower-order systems i.e., Ni-W, Al-Ni-W and Cr-Ni-W by performing key experiments on three binary Ni-W alloys, and two ternary alloys (Al-Ni-W and Cr-Ni-W). Experiments at four different temperatures were carried out in which alloys were homogenized, equilibrated, quenched and investigated to determine the equilibrium solid/liquid compositions. Experimental results are used to validate the thermodynamic descriptions of the liquid and the fcc phase. Unlike ternary Al-Ni-W and Cr-Ni-W, binary Ni-W reproduced the experimental information in a satisfactory way. Ternary parameters for fcc are changed to fit the experimental results of this work. The findings of this work highlight that ternary parameters for the fcc of Al-Ni-W and Cr-Ni-W systems significantly effect the tungsten partitioning values in higher order systems.Thermo-Calc Software AB utvecklar termodynamiska och kinetiska databaser av hög kvalitet för att korrekt kunna förutsäga och simulera jämvikter och fasomvandlingar i komplexa flerkomponentsystem. Ett problem med deras databas för Ni-baslegeringar och superlegeringar (TCNI8) är att beskrivning av volframpartitionering stämmer dåligt för nickelbaslegeringar. I detta arbete undersöktes den termodynamiska beskrivningen av vissa lägre system, dvs Ni-W, Al-Ni-W och Cr-Ni-W genom att utföra nyckelförsök på tre binära Ni-W-legeringar och två ternära legeringar (Al-Ni-W och Cr-Ni-W). Experimentvid fyra temperaturer utfördes i vilka legeringarna homogeniserades,jämviktsbehandlades, släcktes och undersöktes för att bestämma sammansättning för jämvikt fast fas/smälta. De erhållna experimentella resultaten användes för att validera den termodynamiska beskrivningen av smältan och fcc-fasen. Till skillnad från ternära Al-Ni-W ochCr-Ni-W, reproducerade den experimentella informationen den binära Ni-W-beskrivningen tillfredsställande. Ternära parametrar för fcc justerades efter de experimentella resultaten från detta arbete. Resultaten visar att de ternära parametrarna för fcc i Al-Ni-W och Cr-Ni-W systemen signifikant påverkar volframs fördelning mellan fast fas och smälta i nickelbaslegeringar.
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OSTROWSKA, MARLENA. "Thermodynamic modelling and experimental validation of High Entropy Alloys containing Al, Co, Cr, Fe, Mo, Ni, Ta and W for high-temperature applications." Doctoral thesis, Università degli studi di Genova, 2021. http://hdl.handle.net/11567/1046937.
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The aim of the current project is to contribute to the design of novel High Entropy Alloys (HEAs) which meet targeted industrial needs, for instance the request for new high-temperature alloys.
HEAs attracted a lot of attention due to their promising high temperature mechanical performance. Taking into account a very wide range of alloys that fall into this group of materials, using only experimental investigations would be insufficient in finding new compositions with attractive properties.
The objective is achieved by thermodynamic modelling of the Al-Co-Cr-Fe-Mo-Ni-Ta-W system, through the CALPHAD method, in order to predict the best candidate elements and compositions which can give the required structure.
The reliable and self-consistent database is obtained by assessing several important ternary systems and by adopting published assessments, if they were compatible with the models selected in this work.
The reliability of the database is verified with experimental measurements performed during this work regarding the reference system Al-Co-Cr-Fe-Ni, as well as the critically selected published experimental data regarding several other multicomponent systems containing Mo and W.
The synergy between modelling and experimental validation produce a highly reliable thermodynamic database which allows to screen and quickly identify high performance compositions, with a significant reduction in time and costs with respect to traditional trial and error experiments.
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Bratberg, Johan. "Phase equilibria and thermodynamic properties of high-alloy tool steels : theoretical and experimental approach." Doctoral thesis, Stockholm, 2005. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-453.
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Kjellqvist, Lina. "Studies of Steel/Slag Equilibria using Computational Thermodynamics." Licentiate thesis, Stockholm Stockholm : Materialvetenskap, 2006. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-3914.
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Kjellqvist, Lina. "Thermodynamic description of the Fe-C-Cr-Mn-Ni-O system." Doctoral thesis, Stockholm : Skolan för industriell teknik och management, Kungliga Tekniska högskolan, 2009. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-11100.
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Mao, Huahai. "Thermodynamic modelling and assessment of some alumino-silicate systems." Doctoral thesis, Stockholm, 2005. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-251.
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Pham, thi Tam ngoc. "Caractérisation et modélisation du comportement thermodynamique du combustible RNR-Na sous irradiation." Thesis, Aix-Marseille, 2014. http://www.theses.fr/2014AIXM4044/document.
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Au-dessus d'un taux de combustion seuil ≥ 7 at %, les produits de fission volatils Cs, I, et Te ou métalliques (Mo) sont partiellement relâchés hors du combustible et finissent par constituer une couche de composés de PF qui remplit progressivement le jeu existant entre la périphérie de la pastille et la surface interne de la gaine en acier inoxydable. Nous appelons cette couche JOG pour Joint Oxyde-Gaine. Mon sujet de thèse est axé sur l'étude thermodynamique du système (Cs, I, Te, Mo, O) + (U, Pu) ainsi que sur l'étude de la diffusion de ces produits de fission à travers le combustible vers le jeu combustible-gaine pour former le JOG.L'étude thermodynamique constitue la première étape de mon travail. Sur la base d'une analyse critique des données expérimentales issues de la littérature, les systèmes Cs-Te, Cs-I, Cs-Mo-O ont été modélisés par la méthode CALPHAD. En parallèle, une étude expérimentale a été entreprise pour valider la modélisation CALPHAD du système binaire Cs-Te. Dans une deuxième étape, les données thermodynamiques résultant de la modélisation CALPHAD ont été introduites dans la base de données du code de calcul thermodynamique ANGE (code interne au CEA dérivé du logiciel SOLGASMIX) dont la finalité est le calcul de la composition chimique du combustible irradié. Dans une troisième étape, le code de calcul thermodynamique ANGE (Advanced Numeric Gibbs Energy minimiser) a été couplé avec le code de simulation du comportement thermomécanique du combustible des RNR-Na GERMINAL V2For a burn-up higher than 7 at%, the volatile FP like Cs, I and Te or metallic (Mo) are partially released from the fuel pellet in order to form a layer of compounds between the outer surface of the fuel and the inner surface of the stainless cladding. This layer is called the JOG, french acronym for Joint-Oxyde-Gaine.My subject is focused on two topics: the thermodynamic study of the (Cs-I-Te-Mo-O) system and the migration of those FP towards the gap to form the JOG.The thermodynamic study was the first step of my work. On the basis of critical literature survey, the following systems have been optimized by the CALPHAD method: Cs-Te, Cs-I and Cs-Mo-O. In parallel, an experimental study is undertaken in order to validate our CALPHAD modelling of the Cs-Te system. In a second step, the thermodynamic data coming from the CALPHAD modelling have been introduced into the database that we use with the thermochemical computation code ANGE (CEA code derived from the SOLGASMIX software) in order to calculate the chemical composition of the irradiated fuel versus burn-up and temperature. In a third and last step, the thermochemical computation code ANGE (Advanced Numeric Gibbs Energy minimizer) has been coupled with the fuel performance code GERMINAL V2, which simulates the thermo-mechanical behavior of SFR fuel
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Shu-changWu and 吳舒昌. "Ab initio-aided CALPHAD thermodynamic modeling of the Mo-Nb-Re ternary system." Thesis, 2014. http://ndltd.ncl.edu.tw/handle/298xaf.
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碩士國立成功大學
材料科學及工程學系
102
Conventionally, Ni-based superalloys have been employed as the high-temperature materials for engines that directly determine their efficiency. Rare-earth elements, such as Mo, Nb, Re, etc, are usually alloyed in next-generation superalloys to increase their melting temperatures as well as to enhance their high-temperature mechanical properties. In this works, we employed ab initio-aided CALPHAD modeling for developing the thermodynamic description for the Mo-Nb-Re ternary system. With the computation-assisted materials design, only a few experimental verifications are needed, so progress for new materials developments can be significantly accelerated and the cost can also be reduced. In the Mo-Nb-Re ternary system, there are three solution phases, the liquid, body-centered-cubic (BCC), and hexagonal-close-pack (HCP) phases, and two compounds with noticeable homogeneity ranges, the σ and χ phases. The thermodynamic models of constituent systems, namely the Mo-Nb, Mo-Re, and Nb-Re binary systems, have recently been proposed by Xiong et al., Yang et al., and Liu et al., respectively. However, the compound energy formalism models for the σ phase are different, i.e. (Re)10(Mo,Re)4(Mo,Re)16 in the Mo-Re binary system and (Re)10(Nb)4(Nb,Re)16 in the Nb-Re binary system, and cannot be integrated in the Mo-Nb-Re ternary system. Therefore, we firstly re-optimized the Nb-Re system with a more general sublattice model, (Re)10(Mo,Nb,Re)4(Mo,Nb,Re)16, for the σ phase. In addition, we used special quasi-random (SQS) models to reassess the BCC and HCP phases. Finally, we constructed the tentative thermodynamic parameters of the Mo-Nb-Re ternary system.
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AnsharMakhraja, Muhammad, and 馬牧輝. "Ab initio-aided CALPHAD thermodynamic modeling for the Mo-V and Mo-Zr binary systems." Thesis, 2015. http://ndltd.ncl.edu.tw/handle/60275159162292791763.
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碩士國立成功大學
材料科學及工程學系
103
Superalloys are current used materials for high temperature application. Recently, a new type of alloy called high entropy alloys are found to have a great potential to replace superalloys as material for high temperature application. Investigation on high entropy alloys are mostly done by experiment which is time consuming and costly. In the future, computational method to design High Entropy alloys (HEAs) will be very useful. Computational method need to be done accurately for lower order system before going into high-order alloy system. A well-known computational method to predict materials properties, ab initio calculation based on Density Functional Theory (DFT), has been proven to be a great tool for predicting various material properties. This thesis contains ab initio calculation to predict thermodynamic properties. Ab initio thermodynamic properties calculation is applied into Mo-V and Mo-Zr CALPHAD modeling to improve their thermodynamic description. Mo, V, and Zr are common added element in refractory-HEAs. The thermodynamic description has been assessed in literature. However, experimental phase diagram data and thermochemical data are rarely available. Therefore, ab initio-aided CALPHAD modeling is employed to reassess the Mo-V and Mo-Zr binary systems. Thermodynamic reassessment of Mo-V and Mo-Zr binary systems has been done and the results are closely agreed to the experimental phase diagram in the literature. The assessed parameters are proposed into high-order alloy systems such as HEAs. Furthermore, Mo-V-Zr ternary systems can be developed by assessing V-Zr binary system. Ab initio calculation for V-Zr binary system is presented in the appendix B for the possibility of integrated Mo-V, Mo-Zr, and V-Zr binary systems into Mo-V-Zr ternary systems. Additionally, ab initio elastic properties calculations of pure elements and binary constituents from MoNbHfTiZr HEA are presented in the appendix C. The elastic properties calculations are performed to get some insights into practical application of HEAs. Ab initio calculation successfully predict elastic properties of pure Mo, Nb, Hf, Ti, and Zr In bcc and hcp structure compared with experimental and calculated data from the literature. Furthermore, elastic properties of ten binary alloys from Mo, Nb, Hf, Ti, and Zr in bcc-SQS were calculated.
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Shin, Dongwon. "Thermodynamic properties of solid solutions from special quasirandom structures and CALPHAD modeling application to Al-Cu-Mg-Si and Hf-Si-O /." 2007. http://www.etda.libraries.psu.edu/theses/approved/WorldWideIndex/ETD-1734/index.html.
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Gulapura, Hanumantharaju Arun Kumar. "Thermodynamic modelling ofmartensite start temperature in commercial steels." Thesis, 2018. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-221719.
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Firstly, an existing thermodynamic model for the predicting of martensite start temperature of commercial steels has been improved to include more elements such as N, Si, V, Mo, Nb, W, Ti, Al, Cu, Co, B, P and S and their corresponding composition ranges for Martensitic transformation. The predicting ability of the existing model is improved considerably by critical assessment of different binary and ternary systems i.e. CALPHAD approach which is by wise selection of experimental data for optimization of the interaction parameters. Understanding the degree of variation in multi-component commercial alloys, various ternary systems such as Fe-Ni-X and Fe-Cr-X are optimized using both binary and ternary interaction parameters. The large variations between calculated and the experimental values are determined and reported for improvements in thermodynamics descriptions.Secondly, model for the prediction of Epsilon martensite start temperature of some commercial steels and shape memory alloys is newly introduced by optimizing Fe-Mn, Fe-Mn-Si and other Fe-Mn-X systems considering the commercial aspects in the recent development of light weight steels alloyed with Al and Si.Thirdly, the effect of prior Austenite grain size (pAGS) on martensite start temperature is introduced into the model in the form of non-chemical contribution which will greatly influence the Gibbs energy barrier for transformation. A serious attempt has been made to describe the dependency of transition between lenticular and thin-plate martensite morphologies on the refinement of prior Austenite grain size.Finally, the model is validated using a data-set of 1500 commercial and novel alloys. Including the newly modified thermodynamic descriptions for the Fe-based TCFE9 database by Thermo-Calc software AB, the model has the efficiency to predict the martensite start temperature of Multi-component alloys with an accuracy of (±) 35 K. The model predictability can be further improved by critical assessment of thermodynamic factors such as stacking faults and magnetism in Fe-Mn-Si-Ni-Cr systems.
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Saenko, Ivan. "Thermodynamic modelling as applied to the development of TRIP-Matrix-Composite materials: The Fe–Mg–Mn–Ti–Zr–O system." 2020. https://tubaf.qucosa.de/id/qucosa%3A73318.
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This thesis performed within the Collaborative Research Center 799 describes a development of the metal-ceramic thermodynamic databases as applied to the design of the TRIP-Matrix-Composite materials. A wide range of theoretical and experimental investigations have been carried out in the relevant systems of Fe–Mg–Zr–O, Mg–Ti–Zr–O and Mg–Mn–Zr–O. Thermodynamic data were obtained using experimental methods of calorimetry and ab-initio calculations. Phase relations in the constituent binary and ternary systems have been studied using different types of static and dynamic methods. The obtained results allowed an assessment of thermodynamic parameters of the aforementioned systems using CALPHAD approach. The thermodynamic calculations have been performed to predict interfacial reactions within the composite material as well as to made recommendations for the design and further development of production processes for TRIP-Matrix-Composite materials.