Academic literature on the topic 'Diffraction Microstructure Imaging'
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Journal articles on the topic "Diffraction Microstructure Imaging":
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Isabell, Thomas C., and Vinayak P. Dravid. "Electron Backscattered Diffraction (EBSD) with a Cold Held Emission Gun (cFEG) SEM: Resolution, Sensitivity and Applications." Microscopy and Microanalysis 3, S2 (August 1997): 557–58. http://dx.doi.org/10.1017/s1431927600009673.
Abstract:
A thorough and complete assessment of microstructure of materials requires a wide variety of analytical techniques, which should be sensitive to at all length scales - from mms to atomic scale. While there have been rapid advances in imaging and spectroscopy techniques for microstructural analysis - at all length scales, techniques for crystallographic analysis of microstructure have primarily relied on bulk x-ray/neutron diffraction and TEM. X-ray and neutron diffraction techniques, though very powerful, are primarily bulk techniques and extraction of local crystallography is formidable if not impossible. On the other hand, TEM diffraction techniques provide precise crystallographic information, but at a much smaller length-scale and suffer from poor statistics and tedious specimen preparation procedures. With the advent of commercially available electron backscattered diffraction (EBSD) and orientational imaging (OIM) systems for SEM, and sophisticated pattern recognition procedures, it is now possible to bridge the length-scale gap between bulk and TEM diffraction techniques.
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Sklenička, Vàclav, Petr Král, Jiří Dvořák, Marie Kvapilová, and Milan Svoboda. "Microstructure Evolution and Creep Behavior in ECAP Processed Metallic Materials." Materials Science Forum 783-786 (May 2014): 2689–94. http://dx.doi.org/10.4028/www.scientific.net/msf.783-786.2689.
Abstract:
The creep behavior of high purity aluminum and copper, Al-0.2wt.%Sc and Cu-0.2wt.%Zr alloys was examined after processing by equal-channel angular pressing (ECAP) with an emphasis on the link between microstructure and creep. The microstructure was revealed by electron backscatter diffraction (EBSD) and analyzed by stereological methods. Representative microstructural parameters were obtained using orientation imaging microscopy and EBSD on the relationship between creep behavior and microstructure.
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Adams, B. L. "Orientation imaging of microstructures." Proceedings, annual meeting, Electron Microscopy Society of America 52 (1994): 600–601. http://dx.doi.org/10.1017/s0424820100170736.
Abstract:
The complexity of microstructures characteristic of polycrystalline materials presents the serious investigator with many challenges. The materials engineer hopes to associate the important technological properties of these materials with specific (quantifiable) attributes of the microstructure; however, microscopy presents an overwhelming myriad of details over a wide range of scales of inquiry. Thus, the persistent question becomes: What is important in the microstructure relative to a specific property or aspect of material performance? One particular viewpoint, which stems from the modern atomistic interpretation of the structure of solids, is that for polycrystalline materials it is the spatial placement of lattice orientation that is of essential interest.The past decade has seen some remarkable progress in microdiffraction technique in conjunction with the scanning electron microscope. This progress now makes it possible to vigorously pursue the aforementioned lattice-orientational viewpoint. Since 1987 modern SIT (silicon intensified target) vidicon and CCD (charge-coupled device) cameras have been used to capture the backscattered Kikuchi diffraction (BKD) formed in stationary spot mode in the scanning electron microscope.
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Wiskel, J. Barry, Ry Karl, Maro Emakpor, Fateh Fazeli, Chad Cathcart, Tom Zhou, Saber Yu, Doug G. Ivey, and Hani Henein. "Development and Application of a Thermal Microstructure Model of Laminar Cooling of an API X70 Microalloyed Steel." Materials Science Forum 1105 (November 29, 2023): 7–12. http://dx.doi.org/10.4028/p-y88gpk.
Abstract:
A thermal microstructure model of laminar cooling of X70 microalloyed steel skelp was developed to predict the effect of the laminar cooling temperature profile on the through thickness skelp microstructure. Plant trials using infrared video imaging were undertaken to establish the laminar cooling conditions prevalent in the industrial cooling system. The infrared video temperature measurements were used to develop a finite element thermal model of the skelp transiting the entire laminar cooling system. Dilatometer testing of the X70 steel with cooling rates ranging from 1 °C/s to 120 °C/s was undertaken to develop the CCT curve and to quantify austenite decomposition. The predicted thermal profile from the finite element model and the phase transformation behaviour were combined into a thermal microstructural model capable of predicting the phases that would develop through the skelp thickness as a function of the laminar cooling profile. The predicted through thickness microstructures were verified from electron backscattered diffraction (EBSD) phase analysis of industrially produced API X70 skelp.
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Black, David R. "Microstructural characterization using x-ray diffraction imaging." Proceedings, annual meeting, Electron Microscopy Society of America 51 (August 1, 1993): 504–5. http://dx.doi.org/10.1017/s0424820100148356.
Abstract:
X-ray diffraction imaging, also known as x-ray topography, is a powerful tool to study the defect microstructure of single crystals. As the name implies, this technique is based on recording an image of the diffracted x-ray beam from a crystal. Contrast in the image results from point-to-point variation in the diffracted intensity through the crystal. An example of a diffraction image is shown in figure 1. That this image is in some way a topographic representation of the sample can be seen in the impression of differing elevations and textures in different parts of the image. However, since this image is a result of diffraction from the sample the interpretation of the image is much more complex.Diffraction contrast is usually separated into two types: mosaic contrast and extinction contrast. Mosaic contrast occurs for crystals considered to be formed from a collection of small perfect crystal blocks. These blocks have a well defined rocking curve width, the angular range over which they will diffract, and may be slightly misoriented with respect to each other and/or may have different lattice spacing.
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Alvis, Roger, David Dingley, and David Field. "Observation of grain superstructure in thin aluminum films by orientation imaging microscopy." Proceedings, annual meeting, Electron Microscopy Society of America 53 (August 13, 1995): 436–37. http://dx.doi.org/10.1017/s0424820100138555.
Abstract:
The correlation of aluminum alloy reliability data to microstructure has long been the goal of those scientists seeking to model electromigration behavior of interconnects. Traditionally, microstructural information has been acquired through x-ray diffraction , and transmission electron microscopy (TEM). However, each of these techniques is capable of delivering only part of the characterization whole. We describe the application of orientation imaging microscopy (OIM) to thin aluminum alloy films and demonstrate its versatility in providing the key microstructural reliability parameters: namely texture and grain size, as well as providing insight to the microstructure of grain boundaries.OIM was performed on an electromigration test structure (figure 1). The Al-alloy was deposited on titanium and capped with an anti-reflective titanium nitride. Subsequently, the test structure was patterned and capped with a multilayer blanket consisting of silicon nitride (SiN), and SiO2. The structure was annealed after the SOG deposition at 450° C for 90 minutes, seeing no electrical stressing. The die was removed from the package and deprocessed before the OIM was acquired.
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Falk, L. K. L. "SiAlON Microstructures." Key Engineering Materials 403 (December 2008): 265–68. http://dx.doi.org/10.4028/www.scientific.net/kem.403.265.
Abstract:
This paper is focussed on the development of microstructure during liquid phase sintering and post-densification crystallisation heat treatment of ceramic materials based on the α- and β-Si3N4 structures. Grain shape and size distributions, assessed by quantitative microscopy in combination with stereological methods, and fine scale microstructures, investigated by electron diffraction and high resolution imaging and microanalysis in the transmission electron microscope, are discussed in relation to the fabrication process and the overall composition of the ceramic material.
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Blanton, Thomas N. "Applications of X-ray microdiffraction in the imaging industry." Powder Diffraction 21, no. 2 (June 2006): 91–96. http://dx.doi.org/10.1154/1.2204059.
Abstract:
Characterization of materials used in the digital imaging industry has been performed using micro X-ray diffraction (microXRD) techniques. Case studies are described that demonstrate the use of microXRD for identification of phases, texture, and microstructure morphology of components used in imaging applications.
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Dingley, D. J. "Further advances in orientation imaging microscopy." Proceedings, annual meeting, Electron Microscopy Society of America 53 (August 13, 1995): 98–99. http://dx.doi.org/10.1017/s0424820100136866.
Abstract:
Orientation Imaging Microscopy, OIM, is a relatively new technique which provides an image of the surface of polycrystalline material in which the grains are distinguished by their orientation differences, by the strain within them and the type of grain boundaries that separate them. The technique evolved from the work of Dingley and Venables on application of electron backscatter diffraction EBSD in the scanning electron microscope. In OIM, electron backscatter diffraction patterns are obtained successively at regularly spaced points on a sample surface. At each point, the diffraction pattern is captured, transferred to a computer and automatically indexed. Crystal orientation and diffraction line width are measured. Recent advances have been concerned with post data collection image processing.In the following illustration orientation imaging microscopy was used to investigate the microstructure of submicron aluminium, vapour deposited onto single crystal silicon coated with silicon dioxide. The experimental procedure described in reference 2 was adapted using a Philips XL 30 SEM fitted with a tungsten electron gun.
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Zheng, Changlin, Holm Kirmse, Jianguo Long, David E. Laughlin, Michael E. McHenry, and Wolfgang Neumann. "Investigation of (Fe,Co)NbB-Based Nanocrystalline Soft Magnetic Alloys by Lorentz Microscopy and Off-Axis Electron Holography." Microscopy and Microanalysis 21, no. 2 (November 18, 2014): 498–509. http://dx.doi.org/10.1017/s1431927614013592.
Abstract:
AbstractThe relationship between microstructure and magnetic properties of a (Fe,Co)NbB-based nanocrystalline soft magnetic alloy was investigated by analytical transmission electron microscopy (TEM). The microstructures of (Fe0.5Co0.5)80Nb4B13Ge2Cu1 nanocrystalline alloys annealed at different temperatures were characterized by TEM and electron diffraction. The magnetic structures were analyzed by Lorentz microscopy and off-axis electron holography, including quantitative measurement of domain wall width, induction, and in situ magnetic domain imaging. The results indicate that the magnetic domain structure and particularly the dynamical magnetization behavior of the alloys strongly depend on the microstructure of the nanocrystalline alloys. Smaller grain size and random orientation of the fine particles decrease the magneto-crystalline anisotropy and suggests better soft magnetic properties which may be explained by the anisotropy model of Herzer.
Dissertations / Theses on the topic "Diffraction Microstructure Imaging":
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Cuevas, Assunta Mariela. "Microstructure characterization of friction-stir processed nickel-aluminum bronze through orientation imaging microscopy." Thesis, Monterey, Calif. : Springfield, Va. : Naval Postgraduate School ; Available from National Technical Information Service, 2002. http://library.nps.navy.mil/uhtbin/hyperion-image/02sep%5FCuevas.
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Ribart, Clément. "Essais 4D multimodaux et simulations numériques appliqués à l'étude de la plasticité cristalline." Electronic Thesis or Diss., Université Paris sciences et lettres, 2024. http://www.theses.fr/2024UPSLM001.
Abstract:
Comprendre les liens étroits entre microstructure et propriétés est un objectif majeur pour la conception de matériaux de structure. Les métaux présentent une organisation polycristalline hétérogène qui pilote leur performance, d’où la nécessité d’accéder aux quantités mécaniques d’intérêt à l’échelle granulaire, voire intragranulaire. Un large éventail de techniques de caractérisation permet désormais d’observer ces échelles. Des avancées récentes sur les techniques RX, en synchrotron ou en laboratoire, ont contribué à l’essor des expériences multimodales, notamment par la réalisation d’essais in situ en volume non destructifs. En particulier la Tomographie par Constraste de Diffraction (DCT), appartenant à la famille des techniques d’Imagerie de Microstructure par Diffraction (DMI), permet de reconstruire des cartographies 3D de grains avec leurs orientations associées et une morphologie fidèle de la réalité. Les jumeaux numériques obtenus peuvent être utilisés directement pour des simulations. Cette convergence améliorée des modalités expérimentales ou numériques permet d’envisager des jeux de données massifs et unifiés. Cela constitue une opportunité pour mieux appréhender la complexité des mécanismes physiques. L’objectif principal de cette thèse est de contribuer, sur des cas concrets, à démontrer le potentiel de cette approche. Nous introduisons deux jeux de données multimodaux in situ appliqués à l’étude des premiers stades de la plasticité cristalline sur un titane commercialement pur. Nous évaluons d’abord les performances des techniques EBSD, DCT synchrotron et LabDCT utilisées. Une solution de recalage statistique permet de comparer rigoureusement ces modalités. Des mécanismes caractéristiques de plasticité sont ensuite statistiquement mis en évidence en surface et en volume (rotation des grains, glissement plastique et transmission intergranulaire, accumulation de dislocations GND aux joints de grains), ainsi que la formation de sous-grains, observation inédite uniquement permise par mesure DCT. La simulation FFT réalisée sur un volume DCT a permis en outre de valider les performances du modèle de plasticité cristalline continu sauf au voisinage des précipités non modélisés. Le dernier chapitre présente une étude numérique complémentaire des performances de l’algorithme LabDCT, commercialisé parXNovo Technology, sur une microstructure à l’état déformé. Cette étude s’inscrit dans la dynamique d’étendre les capacités de reconstruction des techniques DMI. Nous avons établi des performances satisfaisantes de l’algorithme pour suivre les rotations des grains au cours de la déformation. Par contre le programme n’est pas capable de reconstruire un champ intragranulaire d’orientations fiablesEstablishing microstructure-property relationships is a critical challenge for the design of structural materials. Metals dis-play an heterogeneous polycrystalline organisation which drives their performance, hence the need to access to themechanical quantities of interest at the grain and sub-grain scales. A variety of characterization techniques now givesaccess to those levels of details. Recent progress in synchrotron and laboratory X-ray techniques have contributed to therise of multimodal experiments, especially by allowing non destructive in situ testing. In particular, Diffraction ContrastTomography (DCT), which belongs to the Diffraction Microcrostructure Imaging (DMI) techniques family, allows the re-construction of 3D grain maps with their associated orientations field and actual morphology. These digital twins canbe used directly for simulations. Improved convergence of experimental and numerical modalities leads to unified andmassive databases. This represents an opportunity to unlock the understanding of the complex physical mechanisms atstake. The main objective of the present work is to contribute, with concrete use cases, to demonstrate the potential ofthis approach. We introduce two in situ multimodal datasets applied to incipient crystal plasticity on a commercially puretitanium. First, we assess the performance of the EBSD, synchrotron DCT and LabDCT techniques used. A statisticalregistration technique allows to compare rigorously these modalities. Typical plasticity mechanisms are observed at thesurface and in the volume (grains rotation, plastic slip and intragranular transmission, GND dislocations accumulation atgrain boundaries), as well as the formation of sub grains, an unprecedented observation only enabled by the DCT. Inaddition, the FFT simulation performed on a DCT volume allowed us to validate the performance of the continuous crystalplasticity model, excepted in the vicinity of the non modelized precipitates. The last chapter presents a complementarynumerical study of the performance of the LabDCT algorithm, commercialized by XNovo Technology, on a microstructurein the deformed state. This study lies in the scope of extending the reconstruction applications of DMI techniques. Weshowed good performance of the algorithm for tracking grains rotations during the deformation. On the other hand, the program is not able to reconstruct a reliable intragranular orientation field
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Li, Shiu Fai Frankie. "Imaging of Orientation and Geometry in Microstructures: Development and Applications of High Energy X-ray Diffraction Microscopy." Research Showcase @ CMU, 2011. http://repository.cmu.edu/dissertations/59.
Abstract:
Near-field High Energy X-ray Diffraction Microscopy (HEDM) is a synchrotron based imaging technique capable of resolving crystallographic orientation in a bulk, polycrystalline material non-destructively. Recent advances in data acquisition and analysis methods have led to micron-scale spatial resolution and ≤ 0.1º angular resolution of the measured volumetric orientation maps across millimeter sized samples. This is a significant improvement over the previous generation of three-dimensional X-ray techniques, which provides us with the access of statistically significant microstructure volumes. Combined with the use of state-of-the-art surface mesh generation algorithms, this markedly improved resolution results in the capability to directly measure geometrical evolution, such as grain boundary motion, and material deformation in the form of lattice rotations.
In this thesis, the algorithms and analysis methods recently developed for HEDM are discussed. This includes the descriptions of the robust geometrical extraction methods used for microstructure feature characterization. A set of validation tests for the Forward Modeling Method and the newly developed orientation reconstruction algorithm, the Stratified Monte Carlo Pruning method, is also detailed. By using HEDM to measure the annealing of high purity nickel, grain boundary motion for different boundary types are measured and presented. Moreover, the use of HEDM enabled us to observe the first ever spatially resolved lattice rotation in a high purity copper wire under uni-axial tension, thus demonstrating HEDM’s applicability to defected materials.
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L'Hôte, Gabriel. "Etude de la dynamique des dislocations de monocristaux de cuivre sous chargement cyclique : Emission acoustique et caractérisations microstructurales." Thesis, Lyon, 2019. http://www.theses.fr/2019LYSEI125.
Abstract:
Pendant la déformation plastique des matériaux cristallins, une plasticité douce, faite de nombreux mouvements de dislocations non corrélés peut coexister avec une plasticité plus sauvage, sous la forme de mouvements collaboratifs : les avalanches de dislocations. La coexistence des deux plasticités dépend de la mise en place d’une structure de dislocations, celle-ci étant supposée entraver la propagation des avalanches. On se propose d’étudier la corrélation entre les évolutions microstructurales et les arrangements de dislocations sous chargement cyclique, d'une part, et la nature de la dynamique collective des dislocations, d'autre part, pour le cas de monocristaux de cuivre purs. Différents essais de fatigue à amplitude de contrainte imposée sont effectués pour étudier l’influence (i) du chemin de chargement, (ii) le rapport de chargement et (iii) l’orientation cristallographique sur les phénomènes de plasticité. La technique d’émission acoustique (EA) est utilisée pour étudier les deux types de plasticité. L’EA continue peut-être associée à la plasticité douce, tandis que l'EA discrète, présentant des signaux plus énergétiques que ceux émis en continu sont associés à la plasticité sauvage. Les microstructures de dislocations sont étudiées à l’aide des techniques EBSD (Electron Backscattered Diffraction, pour mesurer la désorientation cristalline) et ECCI (Electron Channeling Contrast Imaging, pour imager les dislocations au MEB) à la fin de chaque palier de fatigue. Le couplage EA-ECCI donne de précieuses informations quant à la dynamique des dislocations. Le suivi par ECCI, lors d’un essai de fatigue à Rσ=0,1 montre qu’une structure de dislocation n’est stable que pour le niveau de contrainte qui la vue naître. L’émergence d'une structure de dislocations constituent un obstacle aux mouvements des avalanches. Toutefois, l’application d’une amplitude de contrainte plus importante permet un réarrangement de la structure, celui-ci se faisant en grande partie sous la forme d’avalanches de dislocations pouvant se déplacer sur de plus longues distances que le libre parcours moyen. Les petits mouvements de dislocations non corrélés sont confinés à l'intérieur des structures de dislocations, entre les arrangements denses de dislocations (cellules, murs, etc.). La plasticité douce est en conséquence de plus en plus restreinte à mesure que le libre parcours moyen diminue. Le rapport de chargement (Rσ=-1) a une grande influence sur la formation des structures de dislocations, avec l’émergence de structures veines, matrices, bandes de glissement persistant et cellules denses, mais aussi sur la dynamique des dislocations, avec une évolution progressive de la plasticité douce au cours des cycles et une réduction du nombre d’avalanches pendant le durcissement du matériau. Concernant l’influence de l’orientation cristallographique, un nombre plus important de systèmes de glissement activés permet de limiter la contribution des avalanches à la plasticitéDuring the plastic deformation of crystalline materials, a soft plasticity, made up of many uncorrelated dislocation movements, can coexist with a wilder plasticity, in the form of collaborative movements: dislocation avalanches. The coexistence of the two plasticities depends on the establishment of a dislocation structure, which is supposed to hinder the spread of avalanches. It is proposed to study the correlation between microstructural evolutions and dislocation arrangements under cyclic loading on the one hand, and the nature of the collective dynamics of dislocations on the other hand, in the case of pure copper single crystals. Various stress imposed fatigue tests are performed to study the influence of (i) the loading path, (ii) the loading ratio and (iii) the crystallographic orientation on the plasticity phenomena. The acoustic emission (EA) technique is used to study both types of plasticity. Continuous EA, which can be considered as background noise resulting from the cumulative effect of many sources, is associated with mild plasticity. Discrete EA, with more energetic signals than those emitted continuously, is associated with wild plasticity. Dislocation microstructures are studied using EBSD (Electron Backscattered Diffraction) and ECCI (Electron Channeling Contrast Imaging) techniques at the end of each fatigue level. The EA-ECCI coupling provides valuable information on the dynamics of dislocations. The monitoring by ECCI, during a fatigue test at Rσ=0.1 shows that a given dislocation structure is stable only for given level of stress. The emergence of a dislocation structure act as an obstacle to avalanche movement. However, the application of a larger stress amplitude allows the rearrangement of the structure, which is largely in the form of dislocation avalanches that can travel longer distances than the dislocation mean free path. Small uncorrelated dislocation movements are confined within the dislocation structures, between dense dislocation arrangements (cells, walls, etc.). Mild plasticity is therefore increasingly restricted as the mean free path decreases. The various tests carried out show that the loading path (at Rσ=0.1) has no influence on the dislocation structure formed, but that the dynamics of the dislocations adapt to the way the material is loaded. The loading ratio (Rσ=-1) has a major influence on the formation of dislocation structures, with the emergence of veins, matrices, persistent slip bands and dense cells, but also on the dynamics of dislocations, with a gradual evolution of mild plasticity during cycles and a reduction in the number of avalanches during the hardening of the material. Concerning the influence of crystallographic orientation, a larger number of activated slip systems limit the contribution of avalanches to plasticity
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(8741097), Ritwik Bandyopadhyay. "ENSURING FATIGUE PERFORMANCE VIA LOCATION-SPECIFIC LIFING IN AEROSPACE COMPONENTS MADE OF TITANIUM ALLOYS AND NICKEL-BASE SUPERALLOYS." Thesis, 2020.
Abstract:
In this thesis, the role of location-specific microstructural features in the fatigue performance of the safety-critical aerospace components made of Nickel (Ni)-base superalloys and linear friction welded (LFW) Titanium (Ti) alloys has been studied using crystal plasticity finite element (CPFE) simulations, energy dispersive X-ray diffraction (EDD), backscatter electron (BSE) images and digital image correlation (DIC).
In order to develop a microstructure-sensitive fatigue life prediction framework, first, it is essential to build trust in the quantitative prediction from CPFE analysis by quantifying uncertainties in the mechanical response from CPFE simulations. Second, it is necessary to construct a unified fatigue life prediction metric, applicable to multiple material systems; and a calibration strategy of the unified fatigue life model parameter accounting for uncertainties originating from CPFE simulations and inherent in the experimental calibration dataset. To achieve the first task, a genetic algorithm framework is used to obtain the statistical distributions of the crystal plasticity (CP) parameters. Subsequently, these distributions are used in a first-order, second-moment method to compute the mean and the standard deviation for the stress along the loading direction (σ_load), plastic strain accumulation (PSA), and stored plastic strain energy density (SPSED). The results suggest that an ~10% variability in σ_load and 20%-25% variability in the PSA and SPSED values may exist due to the uncertainty in the CP parameter estimation. Further, the contribution of a specific CP parameter to the overall uncertainty is path-dependent and varies based on the load step under consideration. To accomplish the second goal, in this thesis, it is postulated that a critical value of the SPSED is associated with fatigue failure in metals and independent of the applied load. Unlike the classical approach of estimating the (homogenized) SPSED as the cumulative area enclosed within the macroscopic stress-strain hysteresis loops, CPFE simulations are used to compute the (local) SPSED at each material point within polycrystalline aggregates of 718Plus, an additively manufactured Ni-base superalloy. A Bayesian inference method is utilized to calibrate the critical SPSED, which is subsequently used to predict fatigue lives at nine different strain ranges, including strain ratios of 0.05 and -1, using nine statistically equivalent microstructures. For each strain range, the predicted lives from all simulated microstructures follow a log-normal distribution; for a given strain ratio, the predicted scatter is seen to be increasing with decreasing strain amplitude and are indicative of the scatter observed in the fatigue experiments. Further, the log-normal mean lives at each strain range are in good agreement with the experimental evidence. Since the critical SPSED captures the experimental data with reasonable accuracy across various loading regimes, it is hypothesized to be a material property and sufficient to predict the fatigue life.
Inclusions are unavoidable in Ni-base superalloys, which lead to two competing failure modes, namely inclusion- and matrix-driven failures. Each factor related to the inclusion, which may contribute to crack initiation, is isolated and systematically investigated within RR1000, a powder metallurgy produced Ni-base superalloy, using CPFE simulations. Specifically, the role of the inclusion stiffness, loading regime, loading direction, a debonded region in the inclusion-matrix interface, microstructural variability around the inclusion, inclusion size, dissimilar coefficient of thermal expansion (CTE), temperature, residual stress, and distance of the inclusion from the free surface are studied in the emergence of two failure modes. The CPFE analysis indicates that the emergence of a failure mode is an outcome of the complex interaction between the aforementioned factors. However, the possibility of a higher probability of failure due to inclusions is observed with increasing temperature, if the CTE of the inclusion is higher than the matrix, and vice versa. Any overall correlation between the inclusion size and its propensity for damage is not found, based on inclusion that is of the order of the mean grain size. Further, the CPFE simulations indicate that the surface inclusions are more damaging than the interior inclusions for similar surrounding microstructures. These observations are utilized to instantiate twenty realistic statistically equivalent microstructures of RR1000 – ten containing inclusions and remaining ten without inclusions. Using CPFE simulations with these microstructures at four different temperatures and three strain ranges for each temperature, the critical SPSED is calibrated as a function of temperature for RR1000. The results suggest that critical SPSED decreases almost linearly with increasing temperature and is appropriate to predict the realistic emergence of the competing failure modes as a function of applied strain range and temperature.
LFW process leads to the development of significant residual stress in the components, and the role of residual stress in the fatigue performance of materials cannot be overstated. Hence, to ensure fatigue performance of the LFW Ti alloys, residual strains in LFW of similar (Ti-6Al-4V welded to Ti-6Al-4V or Ti64-Ti64) and dissimilar (Ti-6Al-4V welded to Ti-5Al-5V-5Mo-3Cr or Ti64-Ti5553) Ti alloys have been characterized using EDD. For each type of LFW, one sample is chosen in the as-welded (AW) condition and another sample is selected after a post-weld heat treatment (HT). Residual strains have been separately studied in the alpha and beta phases of the material, and five components (three axial and two shear) have been reported in each case. In-plane axial components of the residual strains show a smooth and symmetric behavior about the weld center for the Ti64-Ti64 LFW samples in the AW condition, whereas these components in the Ti64-Ti5553 LFW sample show a symmetric trend with jump discontinuities. Such jump discontinuities, observed in both the AW and HT conditions of the Ti64-Ti5553 samples, suggest different strain-free lattice parameters in the weld region and the parent material. In contrast, the results from the Ti64-Ti64 LFW samples in both AW and HT conditions suggest nearly uniform strain-free lattice parameters throughout the weld region. The observed trends in the in-plane axial residual strain components have been rationalized by the corresponding microstructural changes and variations across the weld region via BSE images.
In the literature, fatigue crack initiation in the LFW Ti-6Al-4V specimens does not usually take place in the seemingly weakest location, i.e., the weld region. From the BSE images, Ti-6Al-4V microstructure, at a distance from the weld-center, which is typically associated with crack initiation in the literature, are identified in both AW and HT samples and found to be identical, specifically, equiaxed alpha grains with beta phases present at the alpha grain boundaries and triple points. Hence, subsequent fatigue performance in LFW Ti-6Al-4V is analyzed considering the equiaxed alpha microstructure.
The LFW components made of Ti-6Al-4V are often designed for high cycle fatigue performance under high mean stress or high R ratios. In engineering practice, mean stress corrections are employed to assess the fatigue performance of a material or structure; albeit this is problematic for Ti-6Al-4V, which experiences anomalous behavior at high R ratios. To address this problem, high cycle fatigue analyses are performed on two Ti-6Al-4V specimens with equiaxed alpha microstructures at a high R ratio. In one specimen, two micro-textured regions (MTRs) having their c-axes near-parallel and perpendicular to the loading direction are identified. High-resolution DIC is performed in the MTRs to study grain-level strain localization. In the other specimen, DIC is performed on a larger area, and crack initiation is observed in a random-textured region. To accompany the experiments, CPFE simulations are performed to investigate the mechanistic aspects of crack initiation, and the relative activity of different families of slip systems as a function of R ratio. A critical soft-hard-soft grain combination is associated with crack initiation indicating possible dwell effect at high R ratios, which could be attributed to the high-applied mean stress and high creep sensitivity of Ti-6Al-4V at room temperature. Further, simulations indicated more heterogeneous deformation, specifically the activation of multiple families of slip systems with fewer grains being plasticized, at higher R ratios. Such behavior is exacerbated within MTRs, especially the MTR composed of grains with their c-axes near parallel to the loading direction. These features of micro-plasticity make the high R ratio regime more vulnerable to fatigue damage accumulation and justify the anomalous mean stress behavior experienced by Ti-6Al-4V at high R ratios.
Book chapters on the topic "Diffraction Microstructure Imaging":
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Proudhon, Henry. "Synchrotron Imaging and Diffraction forIn Situ3D Characterization of Polycrystalline Materials." In From Microstructure Investigations to Multiscale Modeling, 1–39. Hoboken, NJ, USA: John Wiley & Sons, Inc., 2017. http://dx.doi.org/10.1002/9781119476757.ch1.
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Popov, D., S. Sinogeikin, C. Park, E. Rod, J. Smith, R. Ferry, C. Kenney-Benson, N. Velisavljevic, and G. Shen. "New Laue Micro-diffraction Setup for Real-Time In Situ Microstructural Characterization of Materials Under External Stress." In Advanced Real Time Imaging II, 43–48. Cham: Springer International Publishing, 2019. http://dx.doi.org/10.1007/978-3-030-06143-2_5.
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"Optimisation of coherent X-ray diffraction imaging at ultrabright synchrotron sources." In Fifth Size Strain Conference. Diffraction Analysis of the Microstructure of Materials, 27–36. Oldenbourg Wissenschaftsverlag, 2008. http://dx.doi.org/10.1524/9783486992564-005.
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Krishnan, Kannan M. "Introduction to Materials Characterization, Analysis, and Metrology." In Principles of Materials Characterization and Metrology, 1–67. Oxford University Press, 2021. http://dx.doi.org/10.1093/oso/9780198830252.003.0001.
Abstract:
Tailoring microstructures is central to materials development for any technological application. Microstructure includes information on the atomic, mesoscopic, and microscopic length scales, and its tailoring is enabled by characterization, which relates synthesis and processing of materials to their structure, properties, and performance. Typically, probe and signal radiations are used to characterize a specimen and their interactions may be elastic or inelastic, and coherent or incoherent. Probes are based on the electromagnetic spectrum, and their characteristics (e.g. energy, wavelength, momentum, polarization) define their interaction with matter, and determine the nature, scope, and details of any characterization method. Probes or signals, can also be electrons, ions, or neutrons. Characterization techniques are classified as spectroscopy, diffraction and scattering, and imaging and microscopy. Principal features of the materials, i.e. details of their electronic structure, including atomic mass, their crystallography, composition, phase, and morphology contribute to the observable signals. Criteria for technique selection also include penetration depth and mean free path, resolution, detection limits, potential damage to the specimen, and specimen preparation requirements; our goal is to maximize information while minimizing damage. Characterization methods find wide use across many disciplines including engineering, scinces, and art conservation.
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Krishnan, Kannan M. "Transmission and Analytical Electron Microscopy." In Principles of Materials Characterization and Metrology, 552–692. Oxford University Press, 2021. http://dx.doi.org/10.1093/oso/9780198830252.003.0009.
Abstract:
Transmission electron microscopy provides information on all aspects of the microstructure — structural, atomic, chemical, electronic, magnetic, etc. — at the highest spatial resolution in physical and biological materials, with applications ranging from fundamental studies to process metrology in the semiconductor industry. Developments in correcting electron-optical aberrations have improved TEM resolution to sub-Å levels. Coherent Bragg scattering (diffraction), incoherent Rutherford scattering (atomic mass), and interference (phase) are some contrast mechanisms in TEM. For phase contrast, optimum imaging is observed at the Scherzer defocus. Magnetic domains are imaged in Fresnel, Foucault, or differential phase contrast (DPC) modes. Off-axis electron holography measures phase shifts of the electron wave, and is affected by magnetic and electrostatic fields of the specimen. In scanning-transmission (STEM) mode, a focused electron beam is scanned across the specimen to sequentially form an image; a high-angle annular dark field detector gives Z-contrast images with elemental specificity and atomic resolution. Series of (S)TEM images, recorded every one or two degrees about a tilt axis, over as large a tilt-range as possible, are back-projected to reconstruct a 3D tomographic image. Inelastically scattered electrons, collected in the forward direction, form the energy-loss spectrum (EELS), and reveal the unoccupied local density of states, partitioned by site symmetry, nature of the chemical species, and the angular momentum of the final state. Energy-lost electrons are imaged by recording them, pixel-by-pixel, as a sequence of spectra (spectrum imaging), or by choosing electrons that have lost a specific energy (energy-filtered TEM). De-excitation processes (characteristic X-ray emission) are detected by energy dispersive methods, providing compositional microanalysis, including chemical maps. Overall, specimen preparation methods, even with many recent developments, including focused ion beam milling, truly limit applications of TEM.
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Krishnan, Kannan M. "Optics, Optical Methods, and Microscopy." In Principles of Materials Characterization and Metrology, 345–407. Oxford University Press, 2021. http://dx.doi.org/10.1093/oso/9780198830252.003.0006.
Abstract:
Propagation of light is described as the simple harmonic motion of transverse waves. Combining waves that propagate on orthogonal planes give rise to linear, elliptical, or spherical polarization, depending on their amplitudes and phase differences. Classical experiments of Huygens and Young demonstrated the principle of optical interference and diffraction. Generalization of Fraunhofer diffraction to scattering by a three-dimensional arrangement of atoms in crystals forms the basis of diffraction methods. Fresnel diffraction finds application in the design of zone plates for X-ray microscopy. Optical microscopy, with resolution given by the Rayleigh criterion to be approximately half the wavelength, works best when tailored to the optimal characteristics of the human eye (λ = 550 nm). Lenses suffer from spherical and chromatic aberrations, and astigmatism. Optical microscopes operate in bright-field, oblique, and dark-field imaging conditions, produce interference contrast, and can image with polarized light. Variants include confocal scanning optical microscopy (CSOM). Metallography, widely used to characterize microstructures, requires polished or chemically etched surfaces to provide optimal contrast. Finally, the polarization state of light reflected from the surface of a specimen is utilized in ellipsometry to obtain details of the optical properties and thickness of thin film materials.
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Kovaleva, Elizaveta, and Dmitry A. Zamyatin. "Revealing microstructural properties of shocked and tectonically deformed zircon from the Vredefort impact structure: Raman spectroscopy combined with SEM microanalyses." In Large Meteorite Impacts and Planetary Evolution VI. Geological Society of America, 2021. http://dx.doi.org/10.1130/2021.2550(18).
Abstract:
ABSTRACT Finite deformation patterns of accessory phases can indicate the tectonic regime and deformation history of the host rocks and geological units. In this study, tectonically deformed, seismically deformed, and shocked zircon grains from a granite sample from the core of the Vredefort impact structure were analyzed in situ, using a combination of Raman spectroscopy, backscatter electron (BSE) imaging, electron backscattered diffraction (EBSD) mapping, electron probe microanalyses (EPMA), energy-dispersive X-ray spectroscopy (EDS) qualitative chemical mapping, and cathodoluminescence (CL) imaging. We aimed to reveal the effects of marginal grain-size reduction, planar deformation bands (PDBs), and shock microtwins on the crystal structure and microchemistry of zircon. Deformation patterns such as PDBs, microtwins, and subgrains did not show any significant effect on zircon crystallinity/metamictization degree or on the CL signature. However, the ratio of Raman band intensities B1g (1008 cm–1) to Eg (356 cm–1) slightly decreased within domains with low misorientation. The ratio values were affected in shocked grains, particularly in twinned domains with high misorientation. B1g/Eg ratio mapping combined with metamictization degree mapping (full width at half maximum of B1g peak) suggest the presence of shock deformation features in zircon; however, due to the lower spatial resolution of the method, they must be used in combination with the EBSD technique. Additionally, we discovered anatase, quartz, goethite, calcite, and hematite micro-inclusions in the studied zircon grains, with quartz and anatase specifically being associated with strongly deformed domains of shocked zircon crystals.
Conference papers on the topic "Diffraction Microstructure Imaging":
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Koronkevich, Voldemar P., and Galina A. Lenkova. "Diffraction method for testing a periodic microstructure." In International Colloquium on Nonconventional Optical Imaging Elements, edited by Jerzy Nowak and Marek Zajac. SPIE, 1994. http://dx.doi.org/10.1117/12.190212.
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Wang, Zhiyu, Christopher Saldana, and Saurabh Basu. "Subsurface Microstructure and Crystallographic Texture in Surface Severe Plastic Deformation Processes." In ASME 2017 12th International Manufacturing Science and Engineering Conference collocated with the JSME/ASME 2017 6th International Conference on Materials and Processing. American Society of Mechanical Engineers, 2017. http://dx.doi.org/10.1115/msec2017-2915.
Abstract:
Severe plastic burnishing was investigated as a promising surface severe plastic deformation technique for generating gradient microstructure surfaces. The deformed state of oxygen free high conductivity copper workpieces during the surface deformation process was determined with high-speed imaging, this complemented by microstructure characterization using orientation image microscopy based on electron backscatter diffraction. Varying deformation levels in terms of both magnitude and gradient on the processed surface were achieved through control of the incident tool angle. Refined microstructures, including laminate grains elongated in the velocity direction and equiaxed sub-micron grains were observed in the subsurface and were found to be controlled by the combined effects of strain and strain rate in the surface deformation process. Additionally, crystallographic texture evolutions were characterized, showing typical shear textures predominately along the <110> partial fiber. The rotation of texture from original ideal orientation positions was related directly to the deformation history produced by sliding process. Based on these observations, a controllable framework for producing the processed surface with expected mechanical and microstructural responses is suggested.
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Tremsin, Anton S. "Applications of Neutron Counting MCP/Timepix Detectors in Neutron Imaging and Diffraction Experiments." In 3D Image Acquisition and Display: Technology, Perception and Applications. Washington, D.C.: Optica Publishing Group, 2023. http://dx.doi.org/10.1364/3d.2023.jw2a.47.
Abstract:
In this talk we will discuss the unique capabilities of neutron counting detectors with Microchannel Plates combined with a Timepix readout for various applications in neutron imaging and diffraction. With such detectors implemented at spallation neutron sources it is now possible to measure simultaneously more than 250,000 neutron transmission spectra, each within a 55 µm pixel. Despite substantial limitations of this method (e.g. integration of materials characteristics along the direction of neutron beam propagation) this novel technique can be attractive for some studies where other techniques fail due to opacity of the materials or due to bulky sample environment equipment. We present the results of studies of microstructure and elemental composition within various polycrystalline and single crystal materials. These experiments enable mapping of residual strain, uniformity of texture and location of various crystalline defects as well as mapping the bulk elemental concentration, all non-destructively. Investigation of dynamic processes, such as water penetration into various porous materials, in-situ crystal growth and annealing of materials as well as neutron imaging of highly radioactive samples will also be presented.
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Basu, Saurabh, Zhiyu Wang, and Christopher Saldana. "Modeling Evolution of Microstructures Beneath Topographically Textured Surfaces Produced Using Shear Based Material Removal." In ASME 2016 11th International Manufacturing Science and Engineering Conference. American Society of Mechanical Engineers, 2016. http://dx.doi.org/10.1115/msec2016-8802.
Abstract:
Tool chatter is envisaged as a technique to create undulations on fabricated biomedical components. Herein, a-priori designed topographies were fabricated using modulate assisted machining of oxygen free high conductivity copper. Subsequently, underpinnings of microstructure evolution in this machining process were characterized using electron back scattered diffraction based orientation imaging microscopy. These underpinnings were related to the unsteady mechanical states present during modulated assisted machining, this numerically modeled using data obtained from simpler machining configurations. In this manner, relationships between final microstructural states and the underlying mechanics were found. Finally, these results were discussed in the context of unsteady mechanics present during tool chatter, it was shown that statistically predictable microstructural outcomes result during tool chatter.
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Große Holthaus, Marzellus, and Kurosch Rezwan. "Comparison of Three Microstructure Fabrication Methods for Bone Cell Growth Studies." In ASME 2008 International Manufacturing Science and Engineering Conference collocated with the 3rd JSME/ASME International Conference on Materials and Processing. ASMEDC, 2008. http://dx.doi.org/10.1115/msec_icmp2008-72198.
Abstract:
Different micropatterning techniques were applied to elucidate the potential for cell proliferation studies on calcium phosphate surfaces. Sintered hydroxyapatite (HA) platelets were microstructured by three different techniques: Aerosol jet printing (M3D®), laser ablation and microcontact printing via polydimethylsiloxane (PDMS) stamps. The microstructures were designed as channels between 1000 and 3000 micron in length, 10 to 220 micron in width and 5 to 110 micron in height. An optical profilometer, a Scanning Electron Microscope (SEM) and X-ray diffraction were used to characterize the microstructures. Cell proliferation tests were carried out by incubating the microstructured ceramic samples in complete cell media for a maximum of seven days. Osteoblast-like cells (MG-63) were used for testing. Each sample was immersed in media in which the cells were already seeded. Imaging was performed by SEM and Fluorescence Microscopy. The cells proliferated on all three differently fabricated microstructures. Cell growth was observed in the microchannels as well as on the microchannel walls or spacers. In particular it turned out, that the microtopology can provoke the cells to elongate aligned to the direction of the microchannels. Non-directional growth was observed on non-structured areas. All three differently fabricated hydroxyapatite microstructuring methods seem to be attractive and promising techniques for use in bone cell growth studies. The applied fabrication techniques show many advantages for fundamental research in the field of cell interaction with ceramic microstructures and may exhibit possible methods of structuring implant surfaces.
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Ji, Lingkang, Li Meng, Yang Li, Chunyong Huo, and Yaorong Feng. "EBSD Study on Transverse Tensile X80 Grade Pipeline Steel." In 2010 8th International Pipeline Conference. ASMEDC, 2010. http://dx.doi.org/10.1115/ipc2010-31251.
Abstract:
Transverse tension testing was carried out on an X80 grade linepipe to investigate the deformation behavior and the evolution of microstructure by means of SEM-EBSD (Electron Backscattered Diffraction) technique. Test results show that uniform elongation could achieve up to 7% in transverse tension for an X80 linepipe. Microstructural analysis shows that primary equiaxed ferrite grains obviously changed after the tension test to elongate along the length of pipeline body, but the substructure did not increase much revealing that the ferrite in X80 steel could contribute to a certain extent for ductile deformation. Orientation imaging of EBSD analysis displays that the texture components, such as γ-texture, and a little Goss and Copper texture, occurred after deformation. Otherwise, a small amount of primary α-texture still remains. It can be recognized that X80 has good deformational stability.
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Narayanan, Badri K., Lisa McFadden, M. J. Mills, and Marie A. Quintana. "Characterization of Weld Metal Deposited With a Self Shielded Flux Cored Electrode for Pipeline Girth Welds and Offshore Structures." In 2010 8th International Pipeline Conference. ASMEDC, 2010. http://dx.doi.org/10.1115/ipc2010-31406.
Abstract:
Pipeline girth welds deposited with a self-shielded flux cored electrode process (FCAW-S) have been characterized to assess the effect of micro-alloying elements on microstructure and precipitate evolution and correlate it to strength and toughness. A 2.0 mm diameter electrode was used to deposit weld metal in a 12.7 mm thick API grade X-70 pipe joint. The weld metal properties were characterized and shown to overmatch the pipe. The DBTT of the weld metal has been determined through Charpy V-Notch toughness measurements. The effect of heat input and welding procedure has been assessed over a range of heat inputs (1–1.5 kJ/mm.). The effect of dilution from the base plate on toughness has been assessed by measuring the sensitivity of weld metal toughness to changes in carbon content. The as-welded region of the weld has been characterized using different characterization techniques. Ferritic weld metal deposited with a self-shielded arc welding process has intentional additions of aluminum, magnesium, titanium and zirconium. This results in a complex precipitation process that has been characterized with a combination of electron microscopy techniques. The effect of micro-alloying additions on the variant selection during the austenite to ferrite transformation and microstructure evolution has been studied with electron back scattered diffraction (EBSD) in conjunction with orientation imaging microscopy (OIM). Transmission electron microscopy (TEM) was used to characterize the precipitate evolution in these welds. The evidence shows that the formation of a spinel oxide is critical for the nucleation of nitrides of zirconium and titanium and prevents the agglomeration of aluminum rich oxides and the formation of large aluminum nitrides. The evolution of precipitate formation is critical to limit large inclusions and improve weld metal toughness. The presence of titanium and zirconium increases the fraction of high angle grain boundaries within the microstructure resulting in increased resistance to crack propagation. The characterization of the microstructures at two different carbon contents indicates the greater propensity to form twin related variants with increase in carbon content. This suggests a lower transformation temperature of austenite and may be the reason for poor toughness.
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Fathy, Ahmed, Muhammad Arif, Clement Afagwu, MD Motiur Rahman, Mujahid Ali, Stefan Iglauer, Nevin Mathew, and Mohamed Mahmoud. "Wettability of Shale/Oil/Brine Systems: A New Physicochemical and Imaging Approach." In International Petroleum Technology Conference. IPTC, 2022. http://dx.doi.org/10.2523/iptc-22177-ms.
Abstract:
Abstract Wetting characteristics of shale/oil/brine systems at reservoir conditions are important for understanding fluid distribution, flow within shale microstructure, and flow back of fracturing fluid. However, shale wettability demonstrates complexity from core to nanoscale due to microstructure heterogeneity. Shale is believed to exbibit mixed wettability such that the organic matter is hydrophobic or oil-wet and the inorganic mineral is hydrophilic or water-wet. Moreover, the application of nanofluids (e.g., silica) as chemical enhanced oil recovery (CEOR) agents has gained growing interest justified by their promising potential. Thus, to elucidate the complex wetting behavior of shale/oil/brine systems before and after exposure to nanofluids, it is essential to consider the influence of broad mineralogy, TOC (Total Organic Carbon), and aging time of shale surfaces in nanofluids. In this paper, a new physicochemical approach coupled with imaging analysis is proposed to emphasize the interactions of shale/decane/brine systems (before and after aging in nanofluids) for precise shale wettability characterization. Here, the wettability of three US shale oil rocks (Eagle Ford, Wolfcamp, and Mancos) was assessed at ambient and HPHT conditions via advancing and receding contact angle measurements followed by wettability assessment post-aging in different nanofluid concentrations (0.1 wt. % to 5 wt. %). Further, the physicochemical features that influence wettability e.g., surface chemistry, mineral composition, TOC, and kerogen maturity have been investigated. These factors have been assessed via sets of physicochemical measurements such as FTIR (Fourier-Transform Infrared Spectroscopy), XRD (X-Ray Diffraction) analysis, SEM (Scanning Electron Microscopy), and AFM (Atomic Force Microscopy) imaging. Furthermore, the varying thermophysical conditions of pressure and temperature are also investigated. The results revealed significant variations in shale initial wettability with Mancos being weakly water-wet while Eagle Ford and Wolfcamp were moderately oil-wet. Moreover, increasing pressure (from 1 MPa to 20 MPa) shifted the wettability of shale rock surfaces towards relatively more oil-wet witnessed by an increase in advancing and receding contact angles. However, no noticeable trend was observed for contact angle variation with temperature. The original wetting behavior of shales is then related to their functional groups and mineralogy. Additionally, shale surfaces witnessed a shift towards a more water-wet state after aging in silica nanofluids at different concentrations. Therefore, this paper provides a new approach for examining the complex shale wettability behavior that relies on a combination of HPHT conditions, physicochemical analysis, and image analysis. Importantly, the results suggest that nanofluid can alter shale wettability towards a more water-wet state – thus showing potential for application as a flowback additive in fracturing or as a CEOR agent in shales.
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Perez, Celeste, Ashley N. Bucsek, and Adam Creuziger. "In-Situ Characterization of Phase Interfaces in CuAlNi during Mechanical Cycling Using Dark-Field X-Ray Microscopy." In SMST 2024. ASM International, 2024. http://dx.doi.org/10.31399/asm.cp.smst2024p0031.
Abstract:
Abstract Interfacial stress fields play a critical role governing the hysteresis and functional fatigue of shape memory alloys. These stress fields manifest at austenite-martensite interfaces (i.e., habit planes) as a consequence of geometric incompatibility between the austenite and martensite phases. As the material approaches transformation, these interfacial stress fields act as an energy barrier, requiring extra energy to be driven into the system to overcome it, resulting in a hysteresis. In addition, increasing the energy in the system also increases dislocation generation, resulting in functional fatigue. In this research, we employ dark-field X-ray microscopy (DFXM), a high-resolution diffraction microstructure imaging technique, to characterize austenite-martensite interfaces and interfacial stress fields during mechanical cycling in a CuAlNi shape memory alloy. The results show, in 3D, the emergence and evolution of individual austenite-martensite interfaces and spatially mapped orientation and elastic strain, including the interfacial elastic strain fields at austenite-martensite interfaces. These findings will contribute to a better understanding of the origins of hysteresis and functional fatigue by investigating interfacial stress fields and dislocation generation at phase interfaces and their effects on macroscopic behavior.
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Field, D. P., J. A. Nucci, and R. R. Keller. "Interconnect Failure Dependence on Crystallographic Structure." In ISTFA 1996. ASM International, 1996. http://dx.doi.org/10.31399/asm.cp.istfa1996p0351.
Abstract:
Abstract A wealth of literature has arisen in the past couple of decades regarding the phenomenon of electromigration. In addition, stress voiding has received considerable attention from the research community. Some of the work on the structural character of these phenomena has focussed on the roles of crystallographic texture and grain boundary structure. It is an experimental fact that the strength of the (111) fiber texture is an indication of interconnect reliability, the stronger the texture, the more reliable the interconnect. It is also presumed that grain boundary diffusivity is a controlling factor in electromigration behavior of polycrystalline lines. Undesirable grain boundary structure is likely a cause of failure in lines with a bamboo structure as well because they are often sites of stress concentration and local incompatibilities. The present study focuses upon electromigration failures in test structures of Al-Cu lines and stress voiding in Cu lines. Texture and grain boundary structure were measured directly on the specimens using electron back-scatter diffraction and orientation imaging. It is observed that a correlation exists between grain boundary structure and void formation in strongly textured polycrystalline lines. Results indicate that secondary orientation (not just the (111) fiber), and boundary structure may be of primary importance in optimizing interconnect microstructure.