Дисертації з теми "Atom Probe Tomography Characterization"
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Chang, Yanhong [Verfasser], Dierk [Akademischer Betreuer] Raabe, and Sandra [Akademischer Betreuer] Korte-Kerzel. "Characterization of H/D in Ti and its alloys with atom probe tomography / Yanhong Chang ; Dierk Raabe, Sandra Korte-Kerzel." Aachen : Universitätsbibliothek der RWTH Aachen, 2019. http://d-nb.info/1195238029/34.
Повний текст джерелаMühlbacher, Marlene. "High-resolution characterization of TiN diffusion barrier layers." Licentiate thesis, Linköpings universitet, Tunnfilmsfysik, 2015. http://urn.kb.se/resolve?urn=urn:nbn:se:liu:diva-120394.
Повний текст джерелаHwang, Junyeon Kaufman M. J. "Characterization and mechanical properties of nanoscale precipitates in modified Al-Si-Cu alloys using transmission electron microscopy and 3D atom probe tomography." [Denton, Tex.] : University of North Texas, 2007. http://digital.library.unt.edu/permalink/meta-dc-3661.
Повний текст джерелаHwang, Junyeon. "Characterization and Mechanical Properties of Nanoscale Precipitates in Modified Al-Si-Cu Alloys Using Transmission Electron Microscopy and 3D Atom Probe Tomography." Thesis, University of North Texas, 2007. https://digital.library.unt.edu/ark:/67531/metadc3661/.
Повний текст джерелаYu, Xinghua. "Characterization and Modeling of Heat Affected Zone Microstucture in a Blast Resistant Steel." The Ohio State University, 2009. http://rave.ohiolink.edu/etdc/view?acc_num=osu1262201157.
Повний текст джерелаWithrow, Travis P. "Computational Modeling of Atom Probe Tomography." The Ohio State University, 2018. http://rave.ohiolink.edu/etdc/view?acc_num=osu1525763934302517.
Повний текст джерелаEngberg, David. "Atom Probe Tomography of TiSiN Thin Films." Licentiate thesis, Linköpings universitet, Tunnfilmsfysik, 2015. http://urn.kb.se/resolve?urn=urn:nbn:se:liu:diva-122724.
Повний текст джерелаYang, Qifeng. "Atom probe tomography research on catalytic alloys and nanoparticles." Thesis, University of Oxford, 2018. http://ora.ox.ac.uk/objects/uuid:f3acdf37-3d23-4893-a4de-12e81712157a.
Повний текст джерелаBennett, Samantha. "Nitride semiconductors studied by atom probe tomography and correlative techniques." Thesis, University of Cambridge, 2011. https://www.repository.cam.ac.uk/handle/1810/236685.
Повний текст джерелаChen, Yi-Sheng. "Characterisation of hydrogen trapping in steel by atom probe tomography." Thesis, University of Oxford, 2017. http://ora.ox.ac.uk/objects/uuid:9d8ee66f-176d-4ac1-aad6-ccb33efc924d.
Повний текст джерелаOberdorfer, Christian [Verfasser], and Guido [Akademischer Betreuer] Schmitz. "Numeric simulation of atom probe tomography / Christian Oberdorfer ; Betreuer: Guido Schmitz." Münster : Universitäts- und Landesbibliothek Münster, 2014. http://d-nb.info/1138282715/34.
Повний текст джерелаMontalvo, Delgado Stephanie Dannett. "Development and application of atom probe tomography to complex zircon grains." Thesis, Curtin University, 2020. http://hdl.handle.net/20.500.11937/81227.
Повний текст джерелаInnocenti, Nicolas. "Interaction of femtosecond laser pulses with nanoscaleSi-tips for atom probe tomography." Thesis, University of Liège, 2010. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-51018.
Повний текст джерелаatom probe, LA-WATAP, field evaporation, femtosecond laser pulse interaction with nanoscale silicon objects, Sommerfeld's half plane problem, FDTD - Yee's scheme.
Zhang, Yi. "Three dimensional atom probe tomography of nanoscale thin films, interfaces and particles." [Ames, Iowa : Iowa State University], 2009.
Знайти повний текст джерелаZhou, Jing. "An Atom-Probe Tomography Study of Phase Separation in Fe-Cr Based Steels." Doctoral thesis, KTH, Metallografi, 2014. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-150796.
Повний текст джерелаQC 20140910
Spinodal Project
Muller, Michael. "Performance, optimisation and applications of pulsed laser atom probe tomography for compound semiconductor analysis." Thesis, University of Oxford, 2010. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.540147.
Повний текст джерелаLuo, Ting. "Study of the mechanisms of silicide formation by isotope diffusion and atom probe tomography." Thesis, Aix-Marseille, 2018. http://www.theses.fr/2018AIXM0413.
Повний текст джерелаWith the downscaling of microelectronic devices, NiSi has been widely used in complementary-metal-oxide-semiconductor (CMOS) transistors as contact on source, drain and gate. However, NiSi suffers from degradation upon annealing at high temperatures. Adding alloying elements is an effective method to increase the stability of nickel monosilicide but the formation sequence of Ni silicides is substantially modified. Therefore, the studies of the phase formation sequence and the stability of monosilicide are of great importance.The solid-state reactions between Ni films alloyed with W and/or Pt and Si substrates were studied mainly by in-situ X-ray diffraction (XRD) and atom probe tomography (APT) using combinatorial analysis of co-deposited gradient films. The phase sequence was monitored by in-situ XRD and APT was used to examine the silicides and reveal the redistribution of alloying elements. The content of alloying elements (W and Pt) has a large impact on the phase sequence of Ni silicides and the kinetics of phase formation. The basic agglomeration mechanism of NiSi thin films was studied. A 15nm pure Ni film was deposited on a Si substrate enriched with isotope multilayers. APT analyses were performed on the sample of Ni/Si (isotope) after an annealing at 600°C. By observing the distribution of Si isotopes (30Si, 29Si and 28Si), whether they maintain a multilayer structure or are mixed together, a mechanism of the agglomeration of NiSi was proposed. This was possible because of the unique capability of APT to observe isotopes in 3D at the atomic scale and it allows a better understanding and to control of the agglomeration of poly-crystalline compound thin films
Bouchikhaoui, Houari [Verfasser], and Guido [Akademischer Betreuer] Schmitz. "Nanoanalysis by atom probe tomography of tunnel magnetoresistive (TMR) structures / Houari Bouchikhaoui ; Betreuer: Guido Schmitz." Münster : Universitäts- und Landesbibliothek Münster, 2016. http://d-nb.info/1141577747/34.
Повний текст джерелаMazumder, Baishakhi. "Physics of the field evaporation of poor conducting materials in the Laser assisted Atom Probe Tomography." Rouen, 2010. http://www.theses.fr/2010ROUES039.
Повний текст джерелаThe laser assisted atom probe tomography is a 3D nanoanalysing technique which gives information in the atomistic scale with sub nanometre spatial resolution. The physical phenomena underlying the field evaporation of poor conductive material is very complex due to the electronic structure of these types of materials. This work deals with the field evaporation study of poor conductive materials starting from semiconductors (Si, SiC, GaAs and InP= to insulating oxides (MgO, TiO2, and HfO2). The surface atoms from the tip shaped specimen are ionized by a standing electric field and the interaction of a femto-laser beam with the tip. The laser tip interaction increases the tip temperature locally, enabling the evaporation of surface atoms. Analyses are done varying different laser parameters (wavelength, energy, etc. ) to understand the underlying evaporation mechanism. Representative models have been developed to support our experimental results. The influence of wavelength and laser energy on the evaporation mechanisms of semiconductors and oxides are determined taking into account the influernce of optical absorption, band bending effect, etc. Various complex and diversified physical phenomena were observed ands understood during this study. Systematic studies, determining the analytical conditions for field evaporation of non conducting materials are evaluated to help future researchers working in related fields. Specifically one of the key factors is the surface optical absorption and the subsequent evaluation of the electron phonon coupling leading to thermal effects. The present thesis is a modest attempt to understand the field evaporation behaviour under femtosecond laser pulse and the physics involved in this framework by experimental results and corresponding interpretation
Dagan, Michal. "3D field ion microscopy and atom probe tomography techniques for the atomic scale characterisation of radiation damage in tungsten." Thesis, University of Oxford, 2016. https://ora.ox.ac.uk/objects/uuid:a575ff83-9101-499e-a54d-23d59f0d4d16.
Повний текст джерелаHuyan, Fei. "A study of "475°C embrittlement" in Fe-20Cr and Fe-20Cr-X (X=Ni, Cu, Mn) alloys." Thesis, KTH, Metallografi, 2012. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-118155.
Повний текст джерелаDeGeorge, Vincent G. "Chemical Partitioning and Resultant Effects on Structure and Electrical Properties in Co-Containing Magnetic Amorphous Nanocomposites for Electric Motors." Research Showcase @ CMU, 2017. http://repository.cmu.edu/dissertations/885.
Повний текст джерелаZschiesche, Hannes. "Formation and segregation in cobalt silicide and manganese germanide thin films : correlative study by electron microscopy and atom probe tomography." Electronic Thesis or Diss., Aix-Marseille, 2019. http://www.theses.fr/2019AIXM0219.
Повний текст джерелаGermanide and silicide thin films have application in different field such as thermoelectricity, magnetism and/or microelectronics. This PhD thesis study the formation, structure and chemistry of Mn5Ge3 thin films, which is interesting due to its ferromagnetic property for possible spintronic devices, and of CoSi2 thin films, which are used as contact materials. Two new epitaxial relationships between Mn5Ge3 grains and (111)Ge have been identified. The chemical purity of Mn5Ge3 has been related to the deposition by magnetron sputtering: Mn5Ge3 thin films grown by reactive-diffusion are relatively pure while the significant incorporation of impurities in Mn5Ge3 grown by non-diffusive reaction is beneficial for the ferromagnetic property. Ti segregation to CoSi2 grain boundaries has been quantified in CoSi2 grown from a Co/Ti/Si thin film. Additionally, an inhomogeneous distribution of Ti at CoSi2 grain boundary has been related to the defect density. A method has been developed for correlative structural and chemical investigations at the atomic scale on selected interfaces. Finally, a method to quantify the triple junction segregation has been proposed
Weber, Juliane Verfasser], Dirk [Akademischer Betreuer] Bosbach, and Georg [Akademischer Betreuer] [Roth. "Fundamental insights into the radium uptake into barite by atom probe tomography and electron microscopy / Juliane Weber ; Dirk Bosbach, Georg Roth." Aachen : Universitätsbibliothek der RWTH Aachen, 2017. http://d-nb.info/1157122507/34.
Повний текст джерелаWeber, Juliane [Verfasser], Dirk Akademischer Betreuer] Bosbach, and Georg [Akademischer Betreuer] [Roth. "Fundamental insights into the radium uptake into barite by atom probe tomography and electron microscopy / Juliane Weber ; Dirk Bosbach, Georg Roth." Aachen : Universitätsbibliothek der RWTH Aachen, 2017. http://d-nb.info/1157122507/34.
Повний текст джерелаZelenty, Jennifer Evelyn. "Effects of nickel and manganese on the embrittlement of low-copper pressure vessel steels." Thesis, University of Oxford, 2016. https://ora.ox.ac.uk/objects/uuid:28b9151f-1644-470b-abc7-48ff82bcffdd.
Повний текст джерелаLotharukpong, Chalothorn. "Defect characterisation in multi-crystalline silicon." Thesis, University of Oxford, 2015. http://ora.ox.ac.uk/objects/uuid:a803fada-2296-41c3-9d96-864c186957a2.
Повний текст джерелаMeher, Subhashish. "Comparative Coarsening Kinetics of Gamma Prime Precipitates in Nickel and Cobalt Base Superalloys." Thesis, University of North Texas, 2014. https://digital.library.unt.edu/ark:/67531/metadc699871/.
Повний текст джерелаNaber, Christoph [Verfasser], Jürgen [Akademischer Betreuer] Neubauer, and Jürgen [Gutachter] Neubauer. "Hydration kinetics of tricalcium silicate: A dataset for reaction rate calculations and nanoscale analysis employing atom probe tomography / Christoph Naber ; Gutachter: Jürgen Neubauer ; Betreuer: Jürgen Neubauer." Erlangen : Friedrich-Alexander-Universität Erlangen-Nürnberg (FAU), 2019. http://d-nb.info/1176809806/34.
Повний текст джерелаWang, Danqi. "LOW-TEMPERATURE GAS-PHASE CARBURIZING AND NITRIDING OF 17-7 PH STAINLESS STEEL." Case Western Reserve University School of Graduate Studies / OhioLINK, 2014. http://rave.ohiolink.edu/etdc/view?acc_num=case1386165240.
Повний текст джерелаLambeets, Sten. "Hydrogénation catalytique du CO2 sur le rhodium :étude des processus en surface et sous-surface par techniques d’émission de champ." Doctoral thesis, Universite Libre de Bruxelles, 2018. http://hdl.handle.net/2013/ULB-DIPOT:oai:dipot.ulb.ac.be:2013/263477.
Повний текст джерелаDoctorat en Sciences
info:eu-repo/semantics/nonPublished
Shima, Kohei, Yuan Tu, Bin Han, Hisashi Takamizawa, Hideharu Shimizu, Yasuo Shimizu, Takeshi Momose, Koji Inoue, Yasuyoshi Nagai, and Yukihiro Shimogaki. "Characterization and Process Development of CVD/ALD-based Cu(Mn)/Co(W) Interconnect System." Universitätsbibliothek Chemnitz, 2016. http://nbn-resolving.de/urn:nbn:de:bsz:ch1-qucosa-207279.
Повний текст джерелаXiong, Wei. "Thermodynamic and Kinetic Investigation of the Fe-Cr-Ni System Driven by Engineering Applications." Doctoral thesis, KTH, Termodynamisk modellering, 2012. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-96707.
Повний текст джерелаQC 20120612
Hero-m
Zhou, Jing. "Experimental study of phase separation in Fe-Cr based alloys." Licentiate thesis, KTH, Metallografi, 2013. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-119230.
Повний текст джерелаQC 20130308
Johnson, Lars. "Nanostructuring and Age Hardening in TiSCN, ZrAlN, and TiAlN Thin Films." Licentiate thesis, Linköpings universitet, Tunnfilmsfysik, 2010. http://urn.kb.se/resolve?urn=urn:nbn:se:liu:diva-56221.
Повний текст джерелаGwalani, Bharat. "Developing Precipitation Hardenable High Entropy Alloys." Thesis, University of North Texas, 2017. https://digital.library.unt.edu/ark:/67531/metadc1011755/.
Повний текст джерелаSeelam, Uma Maheswara. "STRUCTURAL CHARACTERIZATION OF SPUTTER-DEPOSITED SS304+XAL (X = 0, 4, 7 AND 10 WT.%) COATINGS AND MECHANICALLY MILLED TI, ZR AND." Doctoral diss., University of Central Florida, 2010. http://digital.library.ucf.edu/cdm/ref/collection/ETD/id/3527.
Повний текст джерелаPh.D.
Department of Mechanical, Materials and Aerospace Engineering;
Engineering and Computer Science
Materials Science & Engr PhD
Di, russo Enrico. "Etude de biais de mesure de composition par SAT dans les matériaux semi-conducteurs." Thesis, Normandie, 2018. http://www.theses.fr/2018NORMR065/document.
Повний текст джерелаLaser-assisted Atom Probe Tomography (La-APT) is a powerful tool for investigating the 3D atomic distribution of the chemical species in a wide variety of semiconductor materials. However, important compositional biases affect atom probe analyses revealing a non-stoichiometric composition. In the thesis a systematic study of selected binary (GaN, GaAs, ZnO) and ternary (AlGaN, MgZnO) semiconductors of high technological interest was developed in order to: (i) obtain a coherent description of the compositional biases in APT; (ii) identify the physical mechanisms leading to these biases; (iii) assess the experimental conditions for which the compositional analysis is reliable. In order to interpret the results, the hypothesis of preferential evaporation of metallic species (Ga, Al, Zn, Mg) at high field and emission of neutral non-metallic molecules (N2, O2) at low field has been proposed. Another important aim of this thesis is materials physics-oriented. It is indeed of utmost importance to study both composition and morphology of some devices of technological interest, such as in multi-quantum-well systems. In this perspective, the knowledge of 3D composition field and morphology is essential because these features determine the optical and electrical properties of the systems. In order to do it, a correlative microscopy approach can be adopted. This approach was successfully applied to the study of ZnO/MgZnO multi-quantum wells designed for quantum cascade lasers. Structural, compositional and optical properties were investigated performing correlative La-APT - Electron Tomography (ET) - micro-PhotoLuminescence (µ-PL) on the same atom probe tip specimens. The complementary APT and ET analyses yield a clear picture of the structure and composition of the system investigated, revealing important decomposition phenomena in the MgZnO alloy. In particular, La-APT proved to be a unique technique for a direct assessment of local composition. Moreover, µ-PL also proved to be extremely useful in order to get information related the composition, supporting La-APT results. Finally, a new correlative in-situ approach in which La-APT and µ-PL are simultaneously performed is presented. Thanks to the development of a specially designed tomographic atom probe, it is shown that µ-PL can be successfully performed on a single Zno/MgZnO atom probe tip during La-APT. This is extremely attractive and challenging because allows to strictly correlating the variation photoluminescence signal with nano-metric scale volumes of the tip evaporated during APT. In principle, the emission of single quantum light emitters (i.e. single QW or QD) can be revealed. The new approach presented can be extended to a wide range of materials, opening new perspectives for correlative studies of single atom probe tips
El, Kousseifi Mike. "Ni silicide contacts : Diffusion and reaction in nanometric films and nanowires." Thesis, Aix-Marseille, 2014. http://www.theses.fr/2014AIXM4349.
Повний текст джерелаThis thesis focuses on the phenomena that occur during the reaction between metal and silicon (silicide) on thin films and nanowires. Indeed, phenomena such as nucleation, lateral growth, normal growth and diffusion must be understood to make contacts for future microelectronic devices. The comparison between the silicide formation on thin films and nanowires is one of the main aspects of this work. Atomic distribution in 3D for the elements in different Ni silicide phase was obtained by atom probe tomography (APT). To enable the analysis of different types of silicon nanowires by APT, several original methods for sample preparation by focused ion beam has been developed and tested. On the other hand, in situ and real-time analysis by X-ray diffraction during the reactive diffusion helped to highlight the importance of the nucleation of a phase and to determine the kinetics of formation of Ni(Pt) silicides, including the reaction on the interfaces and the lateral growth. The characteristic shape associated with the lateral growth was determined by ex-situ transmission electron microscopy analyzes and was compared with the existing theoretical models. Moreover, the determination of the fastest diffusing species by APT provided information on the mechanisms of phase formation and stress relaxation in the silicide
Amichi, Lynda. "Etude du dopage de type p dans des nanostructures de GaN par corrélation entre sonde atomique tomographique et holographie électronique hors axe optique." Thesis, Université Grenoble Alpes (ComUE), 2018. http://www.theses.fr/2018GREAY088/document.
Повний текст джерелаThe aim of the thesis is to develop a methodology for the investigation of Mg which acts as p-type doping in GaN. We relate the spatial distribution of the dopants with their electrical activity which is achieved by coupling two complementary approaches, Atom Probe Tomography (APT) and Off-axis electron holography. These measurements have also been combined with high-resolution electron microscopy (HR-(S)TEM) for the structural characterization. APT is a unique characterization technique, based on the field effect evaporation of individual atoms of a needle shape sample, allowing the analysis of nano-devices both in terms of morphology and composition in three dimensions at the atomic scale. Off-axis electron holography uses an electron biprism to form an interference pattern from which the electrostatic potential arising from the active dopants can be determined. In this work the experimental procedure has been optimized for both techniques including specimen preparation, the microscope parameters and data treatment to recover accurate information about the position and activity of the dopants. For the holography measurements, a careful analysis of the artifacts that are present in these specimen has been performed to understand the effects of specimen preparation and charging under electron irradiation. We have performed these experiments at high temperature in-situ in the TEM (400 °C) as this increases the ionized dopant concentrations and reduces the artifacts that are present in our measurements. Having developed the methodology, these two techniques are then used to study the effect of temperature and dopant concentrations on the growth of Mg-doped GaN by MOCVD. We have been able to show by APT the existence of precipitates of Mg which are present from a concentration of 3E19 cm-3 whose size and density depends on the growth temperature and the total nominal dopant concentration. Their presence reduces the concentration of dopants that are potentially active in the specimens. However, the measurements of active dopants by holography combined with simulations suggest that the presence of these precipitates do not dominate the electrical properties of the material and that even in very highly doped specimens up to 2E20cm-3 the total active dopant concentrations are still higher than expected from previously published studies. The correlation between these techniques will provide valuable information to improve the Mg activation GaN which is currently a big issue for device manufacture
Rouland, Solene. "Etude expérimentale des cinétiques de diffusion et de la ségrégation induite sous irradiation d'alliages modèles et industriel austénitiques." Thesis, Normandie, 2020. http://www.theses.fr/2020NORMR050.
Повний текст джерелаRadiation induced segregation (RIS) is a process identified to be involved in most of the degradation mechanisms of austenitic stainless steels core components of nuclear reactors. During irradiation within the operating temperature range of present and possible prototypes of future reactors, chemical elements of reactor internal metallic components redistribute heterogeneously and segregate on the pre-existent and newly created defects. Local enrichments or depletions levels depend, inter alia, on the element and nature of the defect affected. While mechanisms involved in RIS have already been identified, their kinetics and mutual weigh are still poorly known. Indeed, current theorical models of RIS suffer from a lack of experimental data. These two aspects motivated this study. First, by the determination of interdiffusion kinetics after thermal ageing and under irradiation on model alloys in the Fe-Ni-Cr system. Irradiation effect on diffusion have been studied at 440°C. At this temperature, conventional methods to study diffusion fail to give access to such slow kinetics under reasonable time. Experimental implementation of the nanolayers method on binary and ternary alloys gave, in this case, encouraging results. However, discrepancies between experiments and predictions revealed the need of optimizations on both sides. In the framework of this study, recommendations have been established to account for the effect of the microstructure and the selected ageing conditions on measured effective kinetics. Experiments on model alloys have the great interest to be directly confronted to simulation. Nevertheless, nuclear steels contain a large variety of minor alloying elements and impurities which have shown to play a key role on RIS behaviour. Thus, in a second part, RIS study on various bulk defects of an optimized nuclear austenitic stainless steel, a 316L(N) has been performed. Consequently, nanoscale coupled and correlated techniques (Atom Probe Tomography and Transmission Eelectron Microscopy) have been implemented. Techniques complementarity offered the possibility to associate enrichments to defect crystallography and revealed singular tendencies of RIS depending on the element and the defect involved. Furthermore, a higher nitrogen and niobium content in the steel nominal composition formed primary Z-phase, its stability under irradiation had also been for the first time studied in austenitic stainless steels
Azzam, Ahmad. "Microstructure et cinétique de précipitation dans des superalliages modèles CoAlW." Thesis, Normandie, 2018. http://www.theses.fr/2018NORMR130/document.
Повний текст джерелаSuperalloys are key material in aerospace industry. These materials are used to manufacturing the high temperature part of aeroengines. Currently Ni-based superalloys are the most widely used materials for high temperature applications. Researches for a new generation of superalloys with better properties have lead in 2006 to the discovery of a new stable L12 ordered, Co3(Al,W) phase embedded in the disordered γ-Co solid-solution matrix. This work aims to study the evolution of the microstructure at 900 °C and understanding the mechanism of dissolution and transformation of the γ' phase. Three different alloys with different Al/W ratios are studied here. TEM and MEB analyses are carried out on samples aged at 900 °C forvarious time. We show that γ' is a metastable phase and it dissolves in favor of B2-CoAl and D019-Co3W phases. Moreover, we highlight a mechanism of dissolution by fragmentation along the {111} close packed planes and stacking faults giving rise to D019 phase. We also study the kinetics of precipitation in the low supersaturated alloys.The early stages of precipitation of the γ' phase in a model Co based superalloy have been investigated at 900 °C using electron microscopy and atom probe tomography in the low supersaturated alloys. Nucleation, growth and coarsening stages have been studied with a focus on the temporal evolution of the precipitate composition in the light of recent theoretical developments on phase separation in multicomponent alloys. The experimental data have been confronted to the theories of nucleation and coarsening recently developed for such alloys, which are valid for non-ideal and non-dilute systems, and predict the temporal evolution of both the matrix and precipitate compositions. The rate constant for the mean size evolution of the particles, as derived from experiments, has been compared to the one predicted by the mentioned coarsening theory that accounts for a more accurate description of the thermodynamics of the phases, as compared with more classical approaches. From this comparison the γ/γ' interfacialenergy was derived and found to range between 30 and 48 mJ/m2. The exponents for the temporal evolution of average particles size, number of particles per unit volume were found identical to those for binary alloys during the coarsening regime, as expected, and the temporal evolutions of compositions in both γ and γ' phases were found to evolve as predictedby theory. Indeed, the W content in the particles, measured from atom probe tomography (APT) experiments, was found to significantly decrease with time and the observed evolution is remarkably well described by the theory and therefore is shown to originate from the competition between diffusion and capillarity
Bonef, Bastien. "Analyses d'hétérostructures de semiconducteurs II-VI par sonde atomique tomographique et microscopie électronique en transmission." Thesis, Université Grenoble Alpes (ComUE), 2015. http://www.theses.fr/2015GREAY083/document.
Повний текст джерелаThis PhD work addresses the problem of atomic scale structural characterization of II-VI based heterostructures. The correlative use of atom probe tomography and transmission electron microscopy reveals the structure and composition of interfaces in ZnTe/CdSe superlattices to improve their growth condition. The atomic structure and the atomic Cr distribution are also revealed in (Cd,Cr)Te diluted magnetic semiconductor.When experimental parameters set in the atom probe are optimized, quantitative data can be obtain on both ZnTe and CdSe semiconductors with this technique. Compositions are obtained with the mass spectrum and it has to be correctly indexed. Experimental studies reveal that with the application of a low voltage on the tip and a moderate laser power around 2.5 nJ with a green laser (515 nm), the measured composition in ZnTe and CdSe are close to the stoichiometry between cations and anions. Setting the cations ratio Zn++/Zn+ around 0.06 et Cd++/Cd+ around 0.35 during the evaporation of the field is a reliable way to reach the optimum evaporation condition for different tips and in different atom probes. Those parameters are responsible for lowering the loss in the detection of the ions due to their different evaporation field. However, the application of a low laser power in UV (343 nm) will enhance the spatial resolution of the atom probe and the 3D reconstruction of both semiconductors. Before the evaporation of the superlattices, it is therefore compulsory to define the objectives of the experiment first.Structural studies of ZnTe/CdSe superlattices reveal that interfaces are composed of ZnSe. Their chemistry is obtain by high resolution Z-contrast images, composition profiles obtain by the zeta-factor method in EDX and by the presence of ZnSe molecular ions in the atom probe tomography mass spectrum. Many samples are investigated to highlight the ability of Zn and Se to bind together instead of Cd and Te. Growth condition are improved by taking this information into account and to force the formation of CdTe based interfaces. Despite the growth precaution, ZnSe bonds seem inevitable and it lowers the possibility to finally obtain CdTe interfaces.Atom probe tomography studies correlated with EDX chemical mapping reveal the gathering of Cr in rich region off a few nanometers in the diluted magnetic semiconductor CdCrTe. Both techniques are not reliable to get the composition of this Cr riche regions but they reveal a change in their shapes with the increase of Cr concentration in different samples
Colignon, Yann. "Etude par sonde atomique tomographique de la décomposition spinodale dans le système Fe-Cr en couches minces." Thesis, Aix-Marseille, 2015. http://www.theses.fr/2015AIXM4359.
Повний текст джерелаDecomposition kinetics due to the presence of a miscibility gap in the Fe-Cr system are generally studied in Fe-Cr bulk alloys for which the decomposition occurs in three dimensions. We studied the spinodal decomposition kinetics in Fe-Cr thins films. These thin films have a Cr composition oscillation whose wave vector is perpendicular to the sample surface. The decomposition of the alloy lead an increase of the oscillation amplitude during annealing and thus generate a decomposition in a single dimension. Samples having different oscillation wavelengths have been designed. Annealing treatments at 500°C of these samples were analyzed by atom probe tomography. These results were then compared to AKMC and mean field simulations. Annealing treatments at 500°C of a sample having a composition oscillation with a 22nm wavelength showed an unexpected decrease in oscillation amplitude. Annealing treatments at 500°C of a sample having a composition oscillation with a 6nm wavelength showed several behavior of the composition oscillation. Indeed, the oscillation amplifies by places while damps or changes very little in other places. The presence of O and grain boundaries in thin films may explain these different behaviors
Couturier, Laurent. "Caractérisation des évolutions microstructurales de l'acier inoxydable martensitique à durcissement structural 15-5PH au cours du vieillissement thermique." Thesis, Grenoble, 2014. http://www.theses.fr/2014GRENI045/document.
Повний текст джерелаThe precipitation hardened martensitic stainless steel grade 15-5PH is used in the airplane industryas constitutive material of parts joining reactors to wings. Due to its application it is subjected totemperatures around 300°C leading to its embrittlement. Stainless steels embrittlement in thistemperature range is due to iron-chromium unmixing by spinodal decomposition. In addition, the 15-5PH grade has a complex microstructure comprising copper precipitates responsible for the initialhardening of the alloy, reversed austenite, known in this kind of steels to improve the toughness,which appears during the precipitation thermal treatment and G phase that precipitates duringaging. The evolutions of these microstructure components could also lead to some modifications ofthe material mechanical properties. In order to study the microstructure evolutions we use acombination of characterization techniques aiming at their most complete description. We show thatthe mechanical properties evolution is controlled by the spinodal decomposition of the matrix whoseevolution we are able to depict by simple phenomenological laws. We propose an indirect methodfor the measurement of aging kinetics of the 15-5PH steel, which we have correlated to directmeasurements, and a phenomenological law allowing the prediction of the alloy hardness based onits thermal history
Demoulin, Rémi. "Etude structurale et cartographie du dopage dans des oxydes nanostructurés à base de sillicium." Thesis, Normandie, 2019. http://www.theses.fr/2019NORMR086/document.
Повний текст джерелаThe change of silicon optical and electrical properties induced by size reduction, due to the quantum confinement of charged carriers, is a well-known effect and allowed to develop new optoelectronic devices. As in bulk silicon, doping should allow to optimize these properties in nanostructured silicon. However, the characteristics of doping of nanostructured silicon still misunderstood and many questions, concerning the location of impurities and their activation state, remain unanswered. Moreover, in these materials, the environment of impurities seems to inuence strongly all of their properties. The purpose of this thesis is to get a better understanding of structural characteristics of doping at the atomic scale in function of the nature of the impurity, the host matrix, and the elaboration technic. In this way, we have investigated two di_erent systems using atom probe tomography. The first concerns a rare earth doping of hafnium silicates. We have evidenced that the clustering of HfO2 nano-grains crystallized in their cubic form induced an efficient energy transfer with praseodymium ions. The second system concern the n and p type doping of silicon nanocrystals embedded in silica. We have demonstrated the important introduction of n type impurities (As, P) in the core of every nanocrystals, independently of the elaboration technic. This introduction of impurities should allow the formation of highly doped silicon nanocrystals. A different behavior has been observed in the case of p type doping, represented by the aggregation of Boron at the interface between the nanocrystals and the silica matrix
Badyka, Romain. "Influence des éléments d'alliage sur la cinétique de vieillissement de la ferrite d'aciers inoxydables austéno-ferritiques moulés." Thesis, Normandie, 2018. http://www.theses.fr/2018NORMR072/document.
Повний текст джерелаCast austenitic-ferritic stainless steels are used in primary circuit of 2nd generation nuclearpower plants. At operating temperature (285 °C - 325 °C), evolution of mechanical properties isobserved due to the phase transformations occurring within the ferrite: spinodal decomposition (SD)leading to the formation on a Fe rich phase (α) and a Cr rich phase (α ') and the precipitation of the G-phase at α/α' interfaces. This evolution of the mechanical properties can be prohibitive for thecomponents. If it is well known that the steel composition plays an important role on the evolution ofthe properties (steels less rich in Ni and Mo are less sensitive to aging), the role of solute elements asNi, Mo and Mn on the aging kinetics is not yet known so as the contribution of the G-phase on thehardening during the thermal aging. In this study, the aging kinetics of the ferrite of some austenitic-ferritic stainless steels with or without Mo and model alloys with tuned compositions have been studied by atom probe tomography (APT) and by micro hardness measurements. This works answered the three following questions: - Quantification of the contribution of both spinodal decomposition and G-phase precipitation on hardening of the ferrite: combination of hardening models and data obtained with APT permitted to show that G-phase precipitation is clearly the main contributor to ferrite hardness increase at early stage of ageing in Mo-bearing steels. This is due to the high number density of G-phase particles. In Mo-free steels which have ten times less G-phase particles, contributions of both spinodal decomposition and G-phase precipitation are similar. In both cases, when coarsening of G-phase particles occurs and SD is well developed, SD contribution becomes larger. - Influence of Ni, Mo and Mn on aging kinetics: The study of model alloys with tuned composition has shown that only Ni plays a role on SD by enhancing the decomposition. Mn is a key element for the precipitation of G-phase particles at α/α' interfaces. - Efficiency of regeneration heat treatment at 550 °C: an alternative to component replacement is to perform a heat treatment at higher temperature in order to restore the properties of the components. The heat treatments performed permitted to entirely restore the mechanical properties of Mo free steels and partially the properties of Mo bearing ones. This is due to the presence of undissolved G-phase particles in the case of Mo bearing alloys. In each case, SD was totally dissolved
Diallo, Lindor. "Etude à l'échelle atomique de l'implantation du fer dans le carbure de silicium (SiC) : Elaboration d'un semiconducteur magnétique dilué à température ambiante." Thesis, Normandie, 2019. http://www.theses.fr/2019NORMR053.
Повний текст джерелаThis PhD thesis focuses on the study of SiC, doped with Fe in order to elaborate a diluted magnetic semiconductor at room temperature for spintronic applications. The iron doping was carried out by ion implantation of multi-energy type (30-160 keV) at different fluences, leading to a 2% constant atomic concentration between 20 to 100 nm, followed by a high temperature annealing in the goal of homogenizing the dopant concentration. The implantation temperature during this process is 550 °C, in order to avoid amorphization. The optimization of the magnetic and electronic properties of SiC-Fe, as well as the understanding of the physical mechanisms at the origin of induced magnetism, require a thorough characterization of the microstructure of the implanted materials. The objectives of this work are, on the one hand, to carry out an atomic scale study of the nanostructure according to the implantation conditions (temperature, fluence) and the post-implantation annealing and the other hand, to characterize the magnetic properties of implanted materials. In this work, we have shown by atom probe tomographic, the existence of nanoparticles whose the average size increases with the annealing temperature. The chemical mapping of the nanoparticles shows the presence of the Fe-rich phases for the annealed samples. Magnetic study (Mössbauer spectrometry and Squid) shows the ferromagnetic contribution is due to the magnetic nanoparticles and/or the diluted Fe atoms in the matrix. The correlation between structural and magnetic properties allowed showing that diluted Fe atoms and substitute to Si sites contribute to the ferromagnetic contribution below 300 K. In coupling many characterization techniques in order to give a detailed description of the different studied samples, we have shown that the size and nature of the phase present in the nanoparticles depend on the implantation conditions and the annealing temperatures and consequently it is necessary to anneal our samples at high temperature to reveal ferromagnetic order
Le, Nué Charline. "Étude de la relation microstructure/ténacité d'aciers maraging inoxydables." Thesis, Ecole nationale des Mines d'Albi-Carmaux, 2017. http://www.theses.fr/2017EMAC0003.
Повний текст джерелаThe stainless maraging steel MLX17, produced and developed by Aubert & Duval, is a candidate for applications in the field of the aeronautics. This steel possesses a high potential in term of mechanical resistance that exceeds that of the other stainless steels. However, the fracture toughness of this grade proves to be sensitive to the cooling rate after aging, resulting of a dispersal of this property. The research of the scientific origins of the degradation of the fracture toughness by a decrease of the cooling rate (air cooling in comparison to water cooling) is the main objective of this thesis. The microstructure was observed for several aging conditions. An approach using various scales (from micrometric to atomic scale) was necessary because of the complexity of the microstructure. In parallel, the study of tensile mechanical properties and resistance to propagation of cracks was led. The aim was to correlate the mechanical behavior to the microstructural evolution observed for the aging conditions investigated. Microstructural analyses by dilatometry and atomic tomography probe have shown the formation of a complementary precipitation of the hardening phase, responsible of the fracture toughness deterioration. In order to have a better control of this additional precipitation and to make it less fragile, a modification of the aging conditions was proposed. This alternative enabled an improvement of the trade-offs between the high strength and the fracture toughness
Akhatova, Alfiia. "Méthodologie instrumentale à l'échelle atomique pour une meilleure compréhension des mécanismes de ségrégation intergranulaire dans les aciers : application au phosphore." Thesis, Normandie, 2017. http://www.theses.fr/2017NORMR131/document.
Повний текст джерелаIt is well known that the intergranular segregation of phosphorus can diminish the cohesion between grains, resulting in steel embrittlement. Low alloyed bainitic steels used to build nuclear reactor pressure vessel (RPV) generally contain a small amount of phosphorus (in the range of 100 ppm). Continuous exposure to a low neutron dose rate irradiation at intermediate temperature (~300°C) results in radiation embrittlement of RPV steel. Since intergranular segregation of phosphorous can contribute to this embrittlement, for purpose of RPV reliability during operation, it is important to understand the effects of ageing conditions (temperature, irradiation dose etc.), material composition and grain boundary (GB) type on the intensity of phosphorus intergranular segregation. Regarding to literature sources, it was revealed that the intergranular segregation values may strongly vary among different GBs. However, there is a lack of systematic studies in this field.In order to get an accurate and representative description of GB from structural and chemical points of view, different techniques are combined in this work. Atom Probe Tomography technique is utilized as the main tool. This technique is able to explore the 3D atomic distribution of broad variety elements at GB. GB geometry is determined from Transmission Kikuchi Diffraction (TKD) map supplemented by APT reconstruction. To gain a better understanding of segregation mechanisms, models of thermally and radiation-induced segregation were employed