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Artykuły w czasopismach na temat "Microstructural modification"
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Abdalla, Ayad Omran, Astuty Amrin, Roslina Mohammad, and M. A. Azmah Hanim. "Microstructural Study of Newly Designed Ti-6Al-1Fe Alloy through Deformation." Solid State Phenomena 264 (September 2017): 54–57. http://dx.doi.org/10.4028/www.scientific.net/ssp.264.54.
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Recently, iron (Fe) is introduced to substitute vanadium (V) in Ti-alloy. Therefore, new (α+β) titanium alloy, Ti-6Al-1Fe was designed through a complete replacement of V by Fe with major composition modifications of Ti-6Al-4V. This new alloy is believed could provide similar properties of Ti-6Al-4V through modification of its microstructures. Different heat treatments can lead to a diversity of microstructural permutations and combinations. Thus, it is very crucial to study in-depth understanding about the microstructure of Ti-6Al-1Fe. Results reveal that the microstructure of as-received alloy is a typical fine lamellar microstructure. The bi-modal microstructure can be obtained by hot rolling below beta-transus temperature (Tβ) followed by recrystallization treatment at 925°C. While cold rolling followed by recrystallization treatment at 925°C produce equiaxed microstructure.
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Taltavull, Catalina, Belen Torres, Antonio Julio Lopez, and Joaquin Rams. "Relationship between Laser Parameters - Microstructural Modification - Mechanical Properties of Laser Surface Melted Magnesium Alloy AZ91D." Materials Science Forum 765 (July 2013): 678–82. http://dx.doi.org/10.4028/www.scientific.net/msf.765.678.
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Laser surface melting is a high-energy surface treatment that allows modification of the microstructure and surface properties of Mg alloys. In the present work, a high-power diode laser has been used to study the microstructural and mechanical modifications that occur when laser surface treatments are applied to the surface of the AZ91D Mg alloy. Laser-beam power in a range of 375-600 W and laser scanning speeds of 45-60-90 mms-1 has been used to develop a range of laser surface melting treatments. By controlling the laser parameters, two types of surface modifications can be obtained. Complete laser surface melting takes place at high laser input energies whilst at low laser input energies, selective laser surface melting occurs with modification of only one phase in the microstructure of the alloy; the other phase remained unaffected. In terms of mechanical properties, the microstructural modifications introduced by the laser surface treatment implied a hardness homogenization along the melted region.
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Herbster, Maria, Karsten Harnisch, Paulina Kriegel, et al. "Microstructural Modification of TiAl6V4 Alloy to Avoid Detrimental Effects Due to Selective In Vivo Crevice Corrosion." Materials 15, no. 16 (2022): 5733. http://dx.doi.org/10.3390/ma15165733.
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TiAl6V4 wrought alloy is a standard material used for endoprostheses due to its ideal characteristics in terms of osseointegration. However, the insufficient wear and crevice corrosion resistance of TiAl6V4 are limiting factors that can cause clinical problems. Therefore, the objective of this study was to analyze and identify suitable phases and microstructural states of TiAl6V4 alloy with advantageous implant properties by thermal treatments. By varying the temperature and cooling rate, four heat treatment strategies were derived that produced different microstructural states that differed in morphology, arrangement and proportions of phases present. All TiAl6V4 modifications were characterized regarding their microstructure, mechanical, corrosive and tribological properties, as well as cell adhesion. The acicular, martensitic microstructure achieves a significant hardness increase by up to 63% and exhibits improved corrosion and wear resistance compared to the forged condition. Whereas the modified microstructures showed similar electrochemical properties in polarization tests using different electrolytes (PBS with H2O2 and HCl additives), selective α or β phase dissolution occurred under severe inflammatory crevice conditions after four weeks of exposure at 37 °C. The microstructurally selective corrosion processes resemble the damage patterns of retrieved Ti-based implants and provide a better understanding of clinically relevant in vivo crevice corrosion mechanisms. Furthermore, a microstructural effect on cell attachment was determined and is correlated to the size of the vanadium-rich β phase. These key findings highlight the relevance of an adapted processing of TiAl6V4 alloy to increase the longevity of implants.
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Jeong, G. C., H. J. Choi, Yong Ho Sohn, and S. I. Kwun. "Effects of Combined Surface Modification on Adhesion Strength of CrN Coatings for STS420." Defect and Diffusion Forum 297-301 (April 2010): 1334–39. http://dx.doi.org/10.4028/www.scientific.net/ddf.297-301.1334.
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In order to improve the durability and performance of molds and tools, diverse methods of surface modification are used where the adhesion strength between a substrate and coating plays an important role. To improve adhesion strength, a combined surface modification method is often utilized. In this study, adhesion strength and microstructure of various combined surface modifications (i.e., ion-nitriding, Cr intermediate layer, CrN layer and nitrogen ion- implantation) were examined on STS420. Phase constituents, microstructure, adhesion strength and hardness of coating-substrate system with combined surface modification were examined by using optical microscopy, X-ray diffraction, transmission electron microscopy, scratch test, and nano-indentation. The highest adhesion strength was observed when CrN coating was formed by nitrogen implantation on ion-nitrided substrate with a Cr-intermediate layer. Influence of processing sequence and combination is related to microstructural observations and adhesion strength.
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Liu, Z., H. Liu, F. Viejo, Z. Aburas, and M. Rakhes. "Laser-induced microstructural modification for corrosion protection." Proceedings of the Institution of Mechanical Engineers, Part C: Journal of Mechanical Engineering Science 224, no. 5 (2010): 1073–85. http://dx.doi.org/10.1243/09544062jmes1858.
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Laser surface modification of materials by melting and annealing has been the subject of considerable interest as a means of enhancing the corrosion performance of metallic alloys. Microstructural modification without changing surface chemical composition, in terms of homogenization/refinement of microstructures, dissolution/re-distribution of intermetallic particles, and extended solid solubility, resulting from rapid rates of cooling, provides the basis for property enhancement. This paper reviews authors’ work on laser surface melting (LSM) and laser annealing (LA) for the purpose of improved corrosion performance. Microstructural evolution and corrosion performance in a range of metallic alloys, followed by different treatments with different types of lasers, are presented. For LSM of aerospace aluminium alloys, the corrosion mechanisms of the laser-melted alloys have been discussed in the consideration of electrochemical characteristics of intermetallic particles with respect to the aluminium matrix and cooling rates leading to different degrees of refinement/removal of intermetallic particles. For LA of amorphous electroless Ni-W-P plating, porosity formation and grain growth and microstrain/residual stress resulting from laser-induced nanocrystallization are the major concerns, affecting corrosion performance. In addition, potential applications of LSM as pre-treatment method prior to conventional anodizing or post-treatment of thermal sprayed coatings have been demonstrated.
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Zhang, Xiao Feng, and Lutgard C. De Jonghe. "Thermal Modification of Microstructures and Grain Boundaries in Silicon Carbide." Journal of Materials Research 18, no. 12 (2003): 2807–13. http://dx.doi.org/10.1557/jmr.2003.0391.
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Polycrystalline SiC samples hot pressed with aluminum, boron, and carbon sintering additions (ABC-SiC) were characterized using transmission electron microscopy. The study focused on the effects of high-temperature treatment on microstructure. Three temperatures, at which considerable microstructural changes took place, were found to be critical. At a threshold temperature of approximately 1000°C, 1-nm-wide, amorphous intergranular films started to crystallize. At approximately 1300°C, lattice diffusion in SiC grains resulted in nanoprecipits, which could diffuse into grain boundaries and significantly altered composition. Quantitative microanalysis revealed doubled Al content in intergranular films after annealing at 1300°C. Except for crystallization in intergranular films and nano-precipitation in matrix grains, microstructure remained stable until 1600°C, when microstructural changes with volatile features occurred. A brief holding at 1900°C brought marked changes in microstructure, including structural change in intergranular films, dissolved nanoprecipitates, unit cell dilation, and cracking. The results indicate that ABC-SiC is highly promising in structural applications at up to 1500°C.
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Liang, Yu, Hao Ding, Sijia Sun, and Ying Chen. "Microstructural Modification and Characterization of Sericite." Materials 10, no. 10 (2017): 1182. http://dx.doi.org/10.3390/ma10101182.
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Patra, Srabani, Janani Narayanasamy, Thamayanthi Panneerselvam, and Ramaswamy Murugan. "Review—Microstructural Modification in Lithium Garnet Solid-State Electrolytes: Emerging Trends." Journal of The Electrochemical Society 169, no. 3 (2022): 030548. http://dx.doi.org/10.1149/1945-7111/ac5c99.
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Garnet structured solid electrolytes-based lithium metal batteries are the most attractive high energy density electrochemical energy storage candidates for the transportation and grid sectors. Various studies are carried out to address the concerns of lithium garnets as solid electrolytes and improve their electrochemical performance in lithium metal batteries. Interfacial engineering is a widely studied strategy for improving lithium garnet electrolyte-electrode interfacial contact and critical current densities. In the same perspective, microstructural/grain boundary engineering in lithium garnet is an effective strategy for overcoming obstacles and increasing critical current densities (CCD) in lithium metal battery research. The importance of the microstructural properties of the solid electrolyte has been discussed in several investigations. However, a comprehensive overview of the microstructural modification of lithium garnet solid electrolytes and their effect on electrochemical performance is still lacking. This review presents a detailed discussion on the strategies used to modify the microstructure and their impact on performances such as ionic conductivity, interfacial contact, critical current density, dendrite kinetics, etc., of lithium garnet ceramics.
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Florea, Costel, Costică Bejinariu, Ioan Carcea, Viorel Paleu, Daniela Chicet, and Nicanor Cimpoeşu. "Preliminary Results on Microstructural, Chemical and Wear Analyze of New Cast Iron with Chromium Addition." Key Engineering Materials 660 (August 2015): 97–102. http://dx.doi.org/10.4028/www.scientific.net/kem.660.97.
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A new cast-iron material was obtained by melting in an induction furnace. The material was microstructural and chemical characterized before and after a wear test. We analyze the chemical composition of the material at macro-scale using a Spark Spectrometer and at micro-scale using Dispersive Energy Spectrometer. Microstructure before and after the external solicitations was observed using a Scanning Electron Microscope. We also evaluate the influence of external force on the dendrites microstructural and chemical modification.
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Snopiński, Przemysław. "Effect of Al10Sr and TiB on the Microstructure and Solidification Behavior of AlMg5Si2Mn Alloy." Solid State Phenomena 326 (November 2, 2021): 111–24. http://dx.doi.org/10.4028/www.scientific.net/ssp.326.111.
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In the first stage of the experiment, the effect of Al10Sr modification and Al5TiB grain refiner and interaction of both additions on the microstructure of AlMg5Si2Mn alloy and Mg2Si phase morphology was investigated. Then the influence of Al10Sr and Al5TiB addition on nucleation temperatures of various intermetallic phases formed in AlMg5Si2Mn alloy also have been interpreted by the formation of distinct peaks in the first derivative cooling curve and microstructural observations. It was found that modification has a meaningful influence on the microstructure of the investigated alloy as well as the crystallization process
Rozprawy doktorskie na temat "Microstructural modification"
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Illing, Cyprian A. W. "Chemical Mechanisms and Microstructural Modification of Alloy Surface Activation for Low-Temperature Carburization." Case Western Reserve University School of Graduate Studies / OhioLINK, 2018. http://rave.ohiolink.edu/etdc/view?acc_num=case1521753968828438.
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Nafisi, Shahrooz. "Effects of grain refining and modification on the microstructural evolution of semi-solid 356 alloy = Effets de l'affinage des grains et de la modification sur l'évolution microstructurale de l'alliage 356 semi-solide /." Thèse, Chicoutimi : Université du Québec à Chicoutimi, 2006. http://theses.uqac.ca.
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Longworth, Hai Pham. "Microstructural modification of thin films and its relation to the electromigration-limited reliability of VLSI interconnects." Thesis, Massachusetts Institute of Technology, 1992. http://hdl.handle.net/1721.1/13114.
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Liu, Xiaorui. "Crystallographic and microstructural study of as-cast and heat-treated Srmodified Al-12.7Si alloys." Thesis, Université de Lorraine, 2016. http://www.theses.fr/2016LORR0103/document.
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Les alliages aluminium-silicium (Al-Si) ont attiré une attention considérable en raison de leur importance pour les applications industrielles. Dans le présent travail, des alliages à haute pureté (Al-12.7 wt. % Si) avec et sans ajout de strontium (400 ppm), solidifiés lentement en creuset ou de façon dirigée (DS), ont été préparés et traités thermiquement. L'influence de l'ajout de strontium et des post-traitements thermiques sur les caractéristiques microstructuraux et cristallographiques des phases eutectiques a été étudiée de façon systématique. Les caractéristiques de croissance du silicium eutectique (Si) dans l'alliage non modifié ainsi que dans l'Al-12.7Si Sr-modifié ont été étudiés. Pour le cas du non-modifié, la formation répétée de variantes de macles mono-orientées permet une croissance rapide du silicium eutectique selon le mécanisme twin plane re-entrant (TPRE). Microscopiquement, les cristaux de silicium ont une forme de plaque allongée dans la direction <1 1 0> non conforme à la croissance selon <1 1 2> présumée par le modèle TPRE. L'élongation selon <1 1 0> est réalisée par des paires en zigzag <1 1 2> sur des plans de maclage parallèles, conduisant à une disparition alternative et à la création de macles rentrantes à 141°. Ce mécanisme de croissance permet aux cristaux de silicium de n'exposer que les plans {1 1 1} à faible consommation d'énergie à la consolidation. Pour les alliages modifiés au strontium, des changements importants de morphologie apparaissent dans le silicium eutectique, attribuable à la croissance de TPRE restreinte et au maclage induit par les impuretés (IIT). Ce dernier améliore la croissance latérale en formant de nouvelles macles avec des plans de macles parallèles, tandis que le second conduit à une croissance isotrope en formant des macles orientées différemment. Le traitement thermique provoque l'affinement des grains des deux phases eutectiques. L'affinement de l'α-Al se produit en même temps que la fragmentation et la sphéroïdisation du silicium et est principalement lié à la fracture des grains de silicium en raison de leur capacité limitée à accommoder la très grande dilatation thermique l'α-Al, ainsi qu'à la diffusion des atomes d'aluminium au cours du traitement thermique. La rupture du silicium génère une force de "capillarité" qui active la diffusion d'atomes d'aluminium dans la fissure. En raison du caractère de substitution de la diffusion de l'aluminium, la migration des lacunes vers l'intérieur de l'α-Al est induite lorsque l'aluminium se déplace dans les fissures, ainsi les vides de la fracture du silicium sont transférés à l'α-Al. De cette façon, les cristaux d'α-Al sont altérés et déformés. Les défauts cristallins produits, à leur tour, initient la restauration et même la recristallisation du α-Al, ce qui entraîne une diminution de taille de grain. La phase α-Al dans l'alliage de Al-12.7Si-0.04Sr solidifiée directionnellement, affiche une forte texture de fibre <1 0 0> parallèle à la direction de solidification. De très gros grains <1 0 0> α-Al sont principalement formés à la périphérie de l'échantillon cylindrique en raison des directions d'évacuation de chaleur favorables disponibles pour les trois directions [1 0 0]. Après traitement thermique, l'intensité de la texture de la phase α-Al diminue en raison de la restauration et de la recristallisation, mais le type de texture ne change pas. Pour la phase de silicium eutectique dans l'alliage de coulée, il y a deux fibres principales de texture, <1 0 0> et <1 1 0> parallèles à la direction de solidification, accompagnées de deux composantes faibles, <2 2 1> et <1 1 3> dans la même direction. Les fibres <1 0 0> et <1 1 0> correspondent à des grains de silicium situés sur la périphérie et dans le centre de l'échantillon. Les composantes <2 2 1> et <1 1 3> proviennent de plusieurs macles de grains orientés <1 1 0> et <1 0 0>. Les faibles intensités de ces deux composantes sont liées à leur fraction volumique mineure [...]<br>Al-Si alloys have attracted considerable attention due to their importance to industrial applications. In the present work, both crucible slowly solidified and slowly directionally solidified (DS) high-purity Al-12.7 wt. % Si alloys with and without 400 ppm Sr addition have been prepared and heat treated. The influence of Sr addition and post heat treatments on the microstructural and crystallographic features of the eutectic phases has been systematically studied. The growth characteristics of eutectic Si in the unmodified and the Sr-modified Al-12.7Si alloys were investigated. For the non-modification case, the formation of repeated single-orientation twin variants enables rapid growth of eutectic Si according to the twin plane re-entrant (TPRE) mechanism. Microscopically, Si crystals are plate-like elongated in one <1 1 0> direction that is not in accordance with the <1 1 2> growth assumed by the TPRE model. The <1 1 0> extension is realized by paired <1 1 2> zigzag growth on parallel twinning planes, leading to alternative disappearance and creation of 141° re-entrants. This growth manner ensures Si crystals to expose only their low-energy {1 1 1} planes to the melt. For the Sr-modification case, substantial changes appear in eutectic Si morphology, attributable to the restricted TPRE growth and the impurity induced twinning (IIT) growth. The first enhances lateral growth by forming new twins with parallel twinning planes, while the second leads to isotropic growth by forming differently oriented twins. Heat treatment brings about refinement of both eutectic phases. The refinement of the α-Al occurs concomitantly with the fragmentation and spheroidization of Si and is mainly related to the fracture of the Si crystals due to their limited capacity to accommodate the giant thermal expansion of the α-Al and the diffusion of Al atoms to the cracks during the heat treatment. The Si fracture generates “capillarity” force that activates the diffusion of Al atoms to the gap of the crack. Due to the substitutional feature of Al diffusion, the migration of vacancies toward the interior of the α-Al is induced when Al moves to the gaps, thus the voids of the Si fracture are transferred to the α-Al. In this way, the crystals of α-Al are distorted and defected. The produced crystal defects, in turn, initiate recovery and even recrystallization of the α-Al, resulting in grain refinement. The α-Al phase in the directionally solidified Al-12.7Si-0.04Sr alloy, displays a strong <1 0 0> fiber texture in the solidification direction. Giant <1 0 0> α-Al grains are mainly formed in the outer circle region of the cylindrical specimen due to the favorable heat evacuation directions available for the three <1 0 0> directions. After heat treatment, the texture intensity of the α-Al phase decreases due to the recovery and recrystallization, but the texture type does not change. For the eutectic Si phase in the as-cast alloy, there are two main fiber texture components, <1 0 0> and <1 1 0> in the DS direction, accompanied by two weak components, <2 2 1> and <1 1 3> in the same direction. The <1 0 0> and <1 1 0> components are from Si crystals located in the outer circle and center regions of the cylindrical specimen. The <2 2 1> and the <1 1 3> components are from multiple twins of the <1 1 0> and <1 0 0> oriented crystals. The weak intensities of these two components are related to their minor volume fraction. Once heat treated, the twinned parts with minor volume fractions enlarge at the expense of their twin related matrix, thus the <1 1 0> component is weakened and accompanied by the intensification of the components from the twins. The disappearance of the <1 1 3> component and the appearance of the <1 1 5> component are due to crystallographic rotation of Si crystals during their fragmentation
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Hecht, Matthew David. "Effects of Heat Treatments and Compositional Modification on Carbide Network and Matrix Microstructure in Ultrahigh Carbon Steels." Research Showcase @ CMU, 2017. http://repository.cmu.edu/dissertations/1023.
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This dissertation investigates microstructure/property relations in ultrahigh carbon steel (UHCS) with the aim of improving toughness while retaining high hardness. Due to high C contents (ranging from 1 to 2 wt%), UHCS exhibit high strength, hardness, and wear resistance. Despite this, applications for UHCS are currently limited because they typically contain a continuous network of proeutectoid cementite that greatly reduces ductility and toughness. In previous research, thermomechanic processing had seen considerable success in breaking up the network. However, the processing is difficult and has thus far seen very limited industrial application. Chemical modification of the steel composition has also seen some success in network break-up, but is still not well understood. There have been relatively few fundamental studies of microstructure evolution in UHCS; studies in the literature typically focused on lower C steels (up to 1 wt% C) or on cast irons (>2.1 wt% C). Thus, this work was undertaken to gain a better understanding of microstructural changes that occur during heat treatment and/or chemical modification of UHCS with a focus on the distribution of proeutectoid cementite within the microstructure. This dissertation is composed of eight chapters. The first chapter presents an introduction to phases found in UHCS, descriptions of research materials used in each chapter, and the hypotheses and objectives guiding the work. The second chapter describes a study of the microstructure found in a 2C-4Cr UHCS before and after an industrial-scale austenitizating heat treatment that increased hardness and toughness and also produced discrete carbide particles in the matrix. The third chapter establishes and demonstrates a metric for measuring connectivity in carbide networks. The fourth chapter describes a series of heat treatments designed to investigate kinetics of spheroidization and coarsening of carbide particles and denuded zones near cementite network branches in 2C-4Cr UHCS. The fifth chapter describes an additional series of heat treatments comparing coarsening kinetics in 2C-1Cr and 2C-4Cr UHCS. Lowering the Cr content caused clustering of cementite particles near grain boundaries, in contrast to the denuded zones observed in the higher Cr UHCS. The fifth chapter details four in situ confocal laser scanning microscopy heat treatments of 2C-4Cr UHCS. The seventh chapter investigates the effects of a 2wt% Nb addition on 2C-4Cr UHCS. The eighth and final chapter summarizes the findings of all the experiments of the previous chapters and revisits the objectives and conclusions.
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Zamani, Mohammadreza. "Al-Si Cast Alloys - Microstructure and Mechanical Properties at Ambient and Elevated Temperature." Licentiate thesis, Tekniska Högskolan, Högskolan i Jönköping, JTH. Forskningsmiljö Material och tillverkning – Gjutning, 2015. http://urn.kb.se/resolve?urn=urn:nbn:se:hj:diva-26805.
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Aluminium alloys with Si as the major alloying element form a class of material providing the most significant part of all casting manufactured materials. These alloys have a wide range of applications in the automotive and aerospace industries due to an excellent combination of castability and mechanical properties, as well as good corrosion resistance and wear resistivity. Additions of minor alloying elements such as Cu and Mg improve the mechanical properties and make the alloy responsive to heat treatment. The aim of this work is studying the role of size and morphology of microstructural constituents (e.g SDAS, Si-particles and intermetalics) on mechanical properties of Al-Si based casting alloy at room temperatures up to 500 ºC. The cooling rate controls the secondary dendrite arm spacing (SDAS), size and distribution of secondary phases. As SDAS becomes smaller, porosity and second phase constituents are dispersed more finely and evenly. This refinement of the microstructure leads to substantial improvement in tensile properties (e.g. Rm and εF). Addition of about 280 ppm Sr to EN AC- 46000 alloy yields fully modified Si-particles (from coarse plates to fine fibres) regardless of the cooling conditions. Depression in eutectic growth temperature as a result of Sr addition was found to be strongly correlated to the level of modification irrespective of coarseness of microstructure. Modification treatment can improve elongation to failure to a great extent as long as the intermetallic compounds are refined in size. Above 300 ºC, tensile strength, Rp0.2 and Rm, of EN AC-46000 alloys are dramatically degraded while the ductility was increased. The fine microstructure (SDAS 10 μm) has superior Rm and ductility compared to the coarse microstructure (SDAS 25 μm) at all test temperature (from room to 500 ºC). Concentration of solutes (e.g. Cu and Mg) in the dendrites increases at 300 ºC and above where Rp0.2 monotonically decreased. The brittleness of the alloy below 300 ºC was related to accumulation of a high volume fraction damaged particles such as Cu- Fe-bearing phases and Si-particles. The initiation rate of damage in the coarse particles was significantly higher, which enhances the probability of failure and decreasing both Rm and εF compared to the fine microstructure. A physically-based model was adapted, improved and validated in order to predict the flow stress behaviour of EN AC- 46000 cast alloys at room temperature up to 400 ºC for various microstructures. The temperature dependant variables of the model were quite well correlated to the underlying physics of the material
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Liu, Jing. "Mechanisms of lifetime improvement in Thermal Barrier Coatings with Hf and/or Y modification of CMSX-4 superalloy substrates." Doctoral diss., University of Central Florida, 2007. http://digital.library.ucf.edu/cdm/ref/collection/ETD/id/3423.
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In modern turbine engines for propulsion and energy generation, thermal barrier coating (TBCs) protect hot-section blades and vanes, and play a critical role in enhancing reliability, durability and operation efficiency. In this study, thermal cyclic lifetime and microstructural degradation of electron beam physical vapor deposited (EB-PVD) Yttria Stabilized Zirconia (YSZ) with (Ni,Pt)Al bond coat and Hf- and/or Y- modified CMSX-4 superalloy substrates were examined. Thermal cyclic lifetime of TBCs was measured using a furnace thermal cycle test that consisted of 10-minute heat-up, 50-minute dwell at 1135C, and 10-minute forced-air-quench. TBC lifetime was observed to improve from 600 cycles to over 3200 cycles with appropriated Hf- and/or Y alloying of CMSX-4 superalloys. This significant improvement in TBC lifetime is the highest reported lifetime in literature with similar testing parameters. Beneficial role of reactive element (RE) on the durability of TBCS were systematically investigated in this study. Photostimulated luminescence spectroscopy (PL) was employed to non-destructively measure the residual stress within the TGO scale as a function of thermal cycling. Extensive microstructural analysis with emphasis on the YSZ/TGO interface, TGO scale, TGO/bond coat interface was carried out by scanning electron microscopy (SEM), transmission electron microscopy (TEM), and scanning electron microscopy (STEM) as a funcion of thermal cycling including after the spallation failure. Focused ion beam in-situ lift-out (FIB-INLO) technique was employed to prepare site-specific TEM specimens. X-ray diffraction (XRD) and secondary ion mass spectroscopy (SIMS) were also employed for phase identification and interfacial chemical analysis. While undulation of TGO/bond coat interface (e.g., rumpling and ratcheting) was observed to be the main mechanism of degradation for the TBCs on baseline CMSX-4, the same interface remained relatively flat (e.g., suppressed rumpling and ratcheting) for durable TBCs on Hf- and/or Y-modified CMSX-4. The fracture paths changed from the YSZ/TGO interface to the TGO/bond coat interface when rumpling was suppressed. The geometrical incompatibility between the undulated TGO and EB-PVD YSZ lead to the failure at the YSZ/TGO interface for TBCs with baseline CMSX-4. The magnitude of copressive residual stress within the TGO scale measured by PL gradually decreased as a function of thermal cycling for TBCs with baseline CMSX-4 superalloy substrates. This gradual decrease corrsponds well to the undulation of the TGO scale that may lead to relaxation of the compressive residual stress within the TGO scale. For TBCs with Hf- and/or Y-modified CMSX-4 superalloy substrates, the magnitude of compressive residual stress within the TGO scale remained relatively constant throughout the thermal cycling, although PL corresponding to the stress-relief caused by localized cracks at the TGO/bond coat interface and within the TGO scale was observed frequently starting 50% of lifetime. A slightly smaller parabolic growth constant and grain size of the TGO scale was observed for TBCs with Hf- and/or Y- modified CMSX-4. Small monoclinic HfO2 precipitates were observed to decorate grain boundaries and the triple pointes within the alpha-Al2O3 scale for TBCs with Hf- and/or Y-modified CMSX-4 substrates. Segregation of Hf/Hf4+ at the TGO/bond coat interfaces was also observed for TBCs with Hf- and/or Y-modified CMSX-4 superalloys substrates. Adherent and pore-free YSZ/TGO interface was observed for TBCs with Hf- and/or Y-modified CMSX-4, while a significant amount of decohesion at the YSZ/TGO interface was observed for TBCs with baseline CMSX-4. The beta-NiAl(B2) phase in the (Ni,Pt)Al bond coat was observed to partially transform into gama prime-Ni3Al (L12) phase due to depletion of Al in the bond coat during oxidation. More importantly, the remaining beta-NiAl phase transformed into L10 martensitic phase upon cooling even though there was no significant difference in these phase transformations for all TBCs. Results from these microstructural observations are documented to elucidate mechanisms that suppress the rumpling of the TGO/bond coat interface, which is responsible for superior performance of EB-PVD TBCs with (Ni,Pt)Al bond coat and Hf- and/or Y-modified CMXS-4 superalloy.<br>Ph.D.<br>Department of Mechanical, Materials and Aerospace Engineering<br>Engineering and Computer Science<br>Materials Science & Engr PhD
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Anyango, Joseph Ochieng. "Physico-chemical modification of kafirin microstructures for application as biomaterials." Thesis, University of Pretoria, 2012. http://hdl.handle.net/2263/29708.
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Microparticles produced from kafirin, the sorghum grain prolamin protein, by molecular selfassembly using coacervation with acetic acid solvent are vacuolated. They have shown considerable potential for encapsulation of antioxidants and for preparation of high quality free-standing bioplastic films. However, the functional quality of these kafirin microstructures needs to be improved to exploit their potential application, particularly as biomaterials. Wet heat, transglutaminase and glutaraldehyde treatments were used to modify the physical structure and chemical properties of the kafirin microstructures. Heat treatment (50–96°C) increased microparticle average size by up to four-fold to ≈20 μm, probably due to disulphide cross-linking of kafirin proteins. The vacuoles within these microparticles enlarged up to >10-fold, probably due to greater expansion of air within the microparticles with higher temperature, as the vacuoles are probably footprints of air bubbles. As with heat treatment, glutaraldehyde (10–30%) treatment resulted in oval microparticles, up to about four-fold larger than the control, probably due to covalent glutaraldehyde-polypeptide linkage. Transglutaminase (0.1–0.6%) treatment had only slight effect on the size and shape of microparticles, probably because kafirin has very low lysine content, inhibiting transglutaminase-catalysed cross-linking through ε-(-glutamyl)-lysine bonding. Surface morphology using atomic force microscopy indicated that the microparticles apparently comprised coalesced nanostructures. With heat and transglutaminase treatments, the microparticles seemed to be composed of round nanostructures that coalesced into random irregular shapes, indicative of non-linear protein aggregation. In contrast, with glutaraldehyde treatment, the nanostructures were spindle-shaped and had a unidirectional orientation, probably due to linear alignment of the nanostructures controlled by glutaraldehyde-polypeptide linkage. Thin (<50 μm) films prepared from kafirin microparticles and conventional cast kafirin films were compared in terms of their water stability and other related properties. Films cast from microparticles were more water-stable compared to conventional kafirin films, probably because the large vacuoles within the kafirin microparticles may have enhanced protein solubility in the casting solution, thereby improving the film matrix cohesion. The films prepared from microparticles treated with glutaraldehyde were more water-stable compared to the control, despite the loss of plasticizer, probably due to formation of the covalent glutaraldehyde-polypeptide linkages. The potential of modified kafirin microparticles to bind bone morphogenetic protein-2 (BMP- 2) was investigated. Compared to a collagen standard, the BMP-2 binding capacity of control, heat-treated, transglutaminase-treated and glutaraldehyde-treated kafirin microparticles were 7%, 18%, 34% and 22% higher, respectively, probably mainly due to the vacuoles within the microparticles creating greater binding surface area. The safety, biodegradability and effectiveness of kafirin microparticle film and kafirin microparticle film-BMP-2 system in inducing bone growth were determined by a subcutaneous bioassay using a rat model. Kafirin microparticle film and kafirin microparticle film-BMP-2 system was non-irritant to the animals, probably because kafirin is non-allergenic. The kafirin microparticle film implants showed signs of some degradation but a large proportion of these implants was still intact by Day 28 post implantation, probably because of the low susceptibility of kafirin to mammalian proteolytic enzymes. Kafirin microparticle film-BMP-2 system did not induce bone growth, probably mainly due to low BMP-2 dosage and short study duration. Modification of kafirin microparticles by wet heat or glutaraldehyde treatment both result in increased size of the microparticles with similar gross structure. However, it is apparent that with both treatments the proteins within the pre-formed kafirin microparticles undergo some form of further assisted-assembly through different mechanisms. It seems that heat-induced disulphide cross-linking reinforces a layer around the nanostructures, probably rich in γ- kafirin polypeptides, that stabilizes the structure of the nanostructures. In contrast, glutaraldehyde-treatment appears to destabilize this structure-stabilizing layer through formation of γ-kafirin polypeptide-glutaraldehyde covalent bonding. This probably offsets the balance of attractive and repulsive forces between the different kafirin subclasses within the nanostructures, thereby resulting in collapsed nanostructures and linear realignment. A deeper understanding of the mechanism of kafirin self-assembly will be important for further development of kafirin microstructures for different applications.<br>Thesis (PhD)--University of Pretoria, 2012.<br>Food Science<br>unrestricted
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Valko, N., S. Anufric, A. Ivanov, and S. Vasiliev. "Laser Modification of the Microstructure of Zn-Co Electroplating Alloys." Thesis, Sumy State University, 2015. http://essuir.sumdu.edu.ua/handle/123456789/42658.
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In this study we report the experimental results of researches of the effect on the microstructure of the Zn-Co coatings with laser radiation generated by a ruby laser operating of free oscillators regime (1.2 ms pulse duration, wavelength 0.69𝜇𝑚 and the power density of 104 to 106 W / cm2). It is shown how the microstructure of the investigating alloys after its modification by an impulse laser radiation depends on the
power density.
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Díez, Escudero Anna. "Tuning the biological performance of calcium phosphates through microstructural and chemical modifications." Doctoral thesis, Universitat Politècnica de Catalunya, 2017. http://hdl.handle.net/10803/620730.
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Bone is the most transplanted tissue after blood. As pointed out by the World Health Organization, musculoskeletal diseases can potentially rise as the fourth largest cause of disability within the next years. Unfortunately, despite the natural ability of bone to self-heal it cannot bridge large bone defects without the help of a material. Still today the gold standard to restore bone function remains the use of natural bone grafts. However, they have several limitations that need to be overcome to accommodate the high demands of a global ageing population.
Calcium phosphate (CaP) bone grafts have been known since the 1970s and stand as excellent synthetic candidates due to their composition, similar to the mineral phase of bone which consists of approximately 70 wt% of hydroxyapatite (HA). CaPs, and in particular HA, possess outstanding intrinsic properties such as biocompatibility, bioactivity and the ability to support bone growth. However, HA is too stable and once implanted it hardly degrades. Ideal synthetic bone grafts should integrate in the bone remodelling cycle, balancing implant resorption with its progressive replacement by new bone. This can be achieved either by modulating the material¿s physicochemical properties, or by combining the substrate with biological molecules capable of adequately orchestrating the various cells involved in the bone healing process.
The present thesis seeks to explore, on the one hand, the feasibility of modulating the physicochemical properties of CaPs towards improving its degradation behavior, and, on the other hand, to investigate the potential CaP functionalization with heparin as a strategy to improve their biological performance at the various stages of bone healing: during the initial phase of inflammation, and during the stages of bone resorption and bone growth.
The first part of the present thesis deals with the in vitro degradation of CaPs in a solution mimicking the osteoclastic environment, focusing specifically on the effect of some properties like porosity, specific surface area, microstructure and composition. The interrelation of all these parameters sometimes masks the relative importance of textural over compositional features, making difficult the prediction of their degradation behavior. Additionally, part of the work explores different strategies to incorporate carbonate ions in the crystal structure of HA as a route to obtain materials that more closely mimic natural bone.
To further mimic the biological environment of bone, the second part of the thesis is focused on grafting heparin, a highly sulfated glycosaminoglycan present in the bone extracellular matrix, to CaPs. The affinity of heparin for growth factors (GF) makes this molecule an excellent candidate to capture endogenous GF bringing many benefits in the regulation of cell behavior. It is hypothesized that heparin, given its anti-inflammatory role, together with the known involvement in osteoblasts differentiation (bone forming cells) and osteoclastogenesis (bone resorbing cells formation) could enhance the biological performance of synthetic bone grafts. To this aim, CaPs were heparinized and their biological performance was assessed using human immune system cells, bone forming cells and bone resorbing cells, in an attempt to elucidate the synergies of both immune cells and cells of the skeletal system.<br>L'os és el teixit més trasplantats desprès de la sang. L'organització Mundial de la Salut ha posat de relleu l'increment de les malalties musculoesquelètiques, les quals esdevindran la quarta causa mundial de discapacitat en el següents anys. Malgrat la capacitat natural de l'ós per autoregenerar-se, els defectes ossis de grans dimensions necessiten l'ajuda de materials per restaurar-se completament. Actualment, l'ús d'empelts naturals és l'alternativa més emprada clínicament. Tot i això, els autoempelts comporten certes limitacions que requereixen ser adreçades per tal de fer front a les elevades demandes d'una població mundial amb un grau d'envelliment creixent. Els empelts basats en fosfats càlcics (CaPs) són coneguts des de la dècada del 1970 i són uns excel·lents candidats per a la regeneració òssia donada la seva composició, similar a la fase mineral de l'os, que consisteix en aproximadament un 70% d'hidroxiapatita (HA). Els CaPs, en particular l'HA, posseeixen unes propietats intrínseques excepcionals com ara la biocompatibilitat, bioactivitat o la capacitat de suportar el creixement de nou os. Malgrat la seva semblança amb l'os, l'HA és massa estable químicament, i un cop implantada es degrada molt lentament. L'empelt ossi sintètic idealment s'hauria d'integrar en el cicle de remodelació òssia, el que requereix d'un balanç entre la seva reabsorció i la progressiva substitució per os nou. Aquesta capacitat es pot modular mitjançant propietats inherents del material o per mitjà de la combinació de substrats amb molècules capaces d'orquestrar adequadament les respostes de les diverses cèl·lules implicades en la restauració o regeneració òssia. La present tesis cerca explorar, per una banda, la possibilitat de modular les propietats físico-químiques dels CaPs per tal de millorar la seva degradació, així com investigar el potencial de funcionalitzar els CaPs amb heparina, amb la finalitat de millorar les interaccions biològiques a les diferents etapes de la restauració òssia, tant durant la primera etapa inflamatòria, com durant la resorció i el creixement d'os nou. Concretament, la primera part de la present tesi explora la manera en què la modificació de propietats com la porositat, la superfície específica, la microestructura o la composició dels CaPs pot ser emprada per regular la degradació d'aquests materials en una solució acídica similar a l'emprada pels osteoclasts durant la resorció òssia. La interrelació de totes aquestes propietats emmascara de vegades la importància relativa de les propietats texturals, molt lligades a les composicionals, dificultant la predicció dels nivells de degradació dels materials depenent de cada propietat. Per tal de mimetitzar encara més la composició de l'os, s'estudiarà també diferents estratègies per incorporar ions carbonat en l'estructura cristal·lina de l'HA. El segon bloc de la tesi explora la funcionalització dels CaPs amb heparina, un tipus de glicosaminoglicà altament sulfonat present en la matriu extracel·lular de l'os. L'afinitat de l'heparina per captar factors de creixement fan d'aquesta molècula un candidat excel·lent per capturar factors de creixement endògens capaços de regular la resposta cel·lular. Així doncs, partint de les propietats anti-inflamatòries de l'heparina, i de la seva implicació en els processos d'osteogènesi i osteoclastogènesi s'ha formulat la hipòtesi de que aquesta biomolècula podria contribuir a millorar les prestacions dels empelts ossis sintètics. Amb aquest objectiu, s'ha posat a punt un procés d'heparinització de CaPs i s'ha avaluat el seu efecte sobre la resposta de cèl·lules humanes del sistema immune, cèl·lules osteogèniques i osteoclàstiques, per tal d'escatir les possibles sinèrgies de tots dos sistemes, l'immune i l'ossi en la regeneració.
Książki na temat "Microstructural modification"
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NATO, Advanced Research Workshop on Atomic and Nanometer-Scale Modification of Materials Fundamentals and Applications (1992 Ventura Calif ). Atomic and nanometer-scale modification of materials, fundamentals and applications. Kluwer Academic Publishers, 1993.
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Roberts, George, George Krauss, and Richard Kennedy. Tool Steels. 5th ed. ASM International, 1998. http://dx.doi.org/10.31399/asm.tb.ts5.9781627083584.
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Tool Steels, Fifth Edition provides tutorial explanations along with engineering data on the production, selection, and use of tool steels and related materials. The first six chapters cover topics of a general nature including tool steel classifications and selection factors, primary production processes, the effects of alloying on microstructure and phase composition, and the theory and practice of tool steel heat treatments. The chapters that follow cover specific types or families of tool steels including water-hardening, low-alloy special-purpose, shock-resisting, oil- and air-hardening cold-work, high-carbon high-chromium cold-work, hot-work, and high-speed types as well as mold steels. Each chapter presents information and data on composition, microstructure, processing, properties, and performance. The current edition also includes two new chapters, one on surface modifications and one that provides guidelines for troubleshooting tool steel manufacturing and performance problems. For information on the print version, ISBN 978-0-87170-599-0, follow this link.
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Michler, Goerg H. Nano- and Micromechanics of Polymers: Structure Modification and Improvement of Properties. Hanser Publications, 2012.
Znajdź pełny tekst źródłaCzęści książek na temat "Microstructural modification"
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Zuo, L., Yu Dong Zhang, Zhuo Chao Hu, H. I. Faraoun, X. Zhao, and Claude Esling. "Microstructural Modification of Metallic Materials by Electromagnetic Processing and the Theoretical Interpretation." In Advanced Materials and Processing IV. Trans Tech Publications Ltd., 2007. http://dx.doi.org/10.4028/0-87849-466-9.123.
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Bennett, Kathleen, Elli Tindall, Samuel R. Wagstaff, and Kenzo Takahashi. "A Reduction in Hot Cracking via Microstructural Modification in DC Cast Billets." In Light Metals 2019. Springer International Publishing, 2019. http://dx.doi.org/10.1007/978-3-030-05864-7_122.
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Osório, Wislei Riuper, Célia Marina A. Freire, and Amauri Garcia. "Microstructural Solidification Parameters of a Zn–4Al Alloy Affecting Mechanical and Corrosion Properties." In Surface Modification Technologies XVIII: Proceedings of the Eighteenth International Conference on Surface Modification Technologies Held in Dijon, France November 15-17, 2004: v. 18, 18th ed. CRC Press, 2023. http://dx.doi.org/10.1201/9781003423874-47.
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Oloyede, Olamilekan, Robert F. Cochrane, and Andrew M. Mullis. "Phase Transformation, Microstructural Evolution and Property Modification in Rapidly Solidified Grey Cast Iron." In TMS 2017 146th Annual Meeting & Exhibition Supplemental Proceedings. Springer International Publishing, 2017. http://dx.doi.org/10.1007/978-3-319-51493-2_69.
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Liu, Y., Y. Zhuge, and W. Duan. "Reusing Alum Sludge as Cement Replacement to Develop Eco-Friendly Concrete Products." In Lecture Notes in Civil Engineering. Springer Nature Singapore, 2023. http://dx.doi.org/10.1007/978-981-99-3330-3_10.
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AbstractAlum sludge is a typical by-product of the water industry. The traditional sludge management method, disposing of sludge in landfill sites, poses a critical environmental and economic concern due to a significant increase in sludge amount and disposal cost. In this paper, the feasibility of reusing sludge as cement replacement is investigated, and the physical performance and microstructure modification of concrete products made with sludge is discussed. The obtained results indicated that a satisfying pozzolanic reactivity of sludge after calcination at high temperatures and grinding to the appropriate size was identified. When 10% cement was replaced with sludge, the reaction degree of sludge was up to 39%, and the obtained concrete blocks exhibited superior mechanical performance. Based on the microstructural analysis, e.g., x-ray diffraction, thermogravimetric analysis, and advanced nanoindentation method, the high aluminum content in sludge was incorporated into C–(A)–S–H gel; the original “Al-minor” C–(A)–S–H gel in pure cement paste was converted to ‘Al-rich’ C–(A)–S–H gel. Also, sludge promoted the formation of aluminum-bearing hydrates, such as ettringite and calcium aluminate hydrates (C–A–H). Although the Al incorporation had no significant effect on the hardness and modulus of C–(A)–S–H gel, the homogeneous mechanical properties (hardness and modulus measured with nanoindentation) of binder paste degraded with increasing sludge ash content above 10%, attributing to the lower hardness of unreacted sludge than cement clinker and the relatively lower reaction degree. Using sludge in concrete products offers an economical and environmentally friendly way to dispose of sludge and preserve diminishing natural resources. Also, the reduction of cement usage may contribute to achieving carbon neutrality.
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Boldyrev, Nikita A., Yuriy I. Yurasov, Lidia A. Shilkina, Alexander V. Nazarenko, and Larisa A. Reznichenko. "Influence of Mn2O3 Modification on the Structural, Microstructural, Dielectric, and Relaxation Characteristics of the (1 − x)BiFeO3–xPbTiO3 Ceramics." In Springer Proceedings in Physics. Springer International Publishing, 2019. http://dx.doi.org/10.1007/978-3-030-19894-7_7.
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Mandal, Sumantra, P. V. Sivaprasad, and V. Subramanya Sarma. "Microstructural Modification in a 15Cr-15Ni-2.2 Mo-Ti Modified Austenitic Stainless Steel through Twin Induced Grain Boundary Engineering." In Ceramic Transactions Series. John Wiley & Sons, Inc., 2008. http://dx.doi.org/10.1002/9780470444214.ch33.
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Samanta, Avik, Hrishikesh Das, David Garcia, et al. "Microstructural Modification of a High-Pressure Die-Cast A380 Alloy Through Friction Stir Processing and Its Effect on Mechanical Properties." In Light Metals 2022. Springer International Publishing, 2022. http://dx.doi.org/10.1007/978-3-030-92529-1_101.
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Grum, Janez. "Residual Stresses and Microstructural Modifications." In Surface Integrity in Machining. Springer London, 2010. http://dx.doi.org/10.1007/978-1-84882-874-2_3.
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Bao, Shenxu. "Modification of Mineral Surfaces and Microstructures." In Adsorption at Natural Minerals/Water Interfaces. Springer International Publishing, 2020. http://dx.doi.org/10.1007/978-3-030-54451-5_3.
Pełny tekst źródłaStreszczenia konferencji na temat "Microstructural modification"
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Zhang, Shuo, Xiaolin Wei, Wenbin Yu, Zheng Lian, and Huaizhi Zhao. "Microstructural Characterization of Zinc Alloy ZA27 with Modification and Heat Treatments." In 5th International Conference on Information Engineering for Mechanics and Materials. Atlantis Press, 2015. http://dx.doi.org/10.2991/icimm-15.2015.53.
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Wu, Fu-Chiao, Tsai-Bau Wu, Horng-Long Cheng, Wei-Yang Chou, and Fu-Ching Tang. "Microstructural modification of polycarbazole-based polymeric solar cells by thermal annealing." In 2014 21st International Workshop on Active-Matrix Flatpanel Displays and Devices (AM-FPD). IEEE, 2014. http://dx.doi.org/10.1109/am-fpd.2014.6867183.
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Yu, Benhai, Deheng Shi, Qiguang Zheng, and Peixiang Lu. "Microstructural modification of lithium niobate crystal induced by femtosecond laser ablation." In International Symposium on Photoelectronic Detection and Imaging: Technology and Applications 2007, edited by Liwei Zhou. SPIE, 2007. http://dx.doi.org/10.1117/12.791237.
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Ahmaniemi, S., J. Tuominen, M. Vippola, et al. "Characterization of Modified Thick Thermal Barrier Coatings." In ITSC2003, edited by Basil R. Marple and Christian Moreau. ASM International, 2003. http://dx.doi.org/10.31399/asm.cp.itsc2003p1477.
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Abstract In gas turbines and diesel engines there is a demand for Thick Thermal Barrier Coatings (TTBCs), because of the increased process combustion temperatures. Unfortunately the increased thickness of plasma sprayed TBCs normally leads to a reduced coating lifetime. So for that reason the coating structures have to be modified. When modifying the structure of TTBCs, the focus is normally set on elastic modulus reduction of the thick coating, in order to improve the coating strain tolerance. On the other hand, coating structural modification procedures, such as sealing treatments, can be performed when increased hot corrosion resistance or better mechanical properties are needed. In this paper we introduced several modified zirconia based TTBC structures and their specific microstructural properties. Coating surface sealing procedures such as phosphate sealing, laser-glazing and sol-gel impregnation were studied as potential methods in increasing the hot corrosion and erosion resistance of TTBCs. Some microstructural modifications were also made by introducing segmentation cracks into the coating structures by laserglazing and by using special spraying parameters. These last two methods were studied in order to increase the strain tolerance of TTBCs. The coating microstructures were characterized by optical microscopy, SEM, TEM, EDS analysis and X-ray diffraction. The effect of sealing procedures was studied on basic thermal and mechanical properties of the coatings. In the paper it was also presented some correlations between the coating properties and microstructures, and discussed about the advantages and drawbacks of each modification procedure.
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Zou, Jia-Hua, Zhi-Chen Zhang, and Shu-Quan Sun. "Enhanced Plasticity of Bulk MetalLic Glass Alloys (BMGs) by Internal Microstructural Modification." In 2011 Second International Conference on Digital Manufacturing and Automation (ICDMA). IEEE, 2011. http://dx.doi.org/10.1109/icdma.2011.127.
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Liu, Jun, Zhencheng Ren, Chi Ma, Yalin Dong, and Chang Ye. "Ultrasonic Nano-Crystal Surface Modification Assisted Gas Nitriding of Ti6Al4V Alloy." 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/msec2017-2847.
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The effects of Ultrasonic Nanocrystal Surface Modification (UNSM) on the gas nitriding of Ti6Al4V alloy has been investigated. The gas nitriding was performed at 700 and 800 °C. The microstructure after UNSM and gas nitriding was characterized using X-ray diffraction and scanning electron microscopy. Microstructural investigations revealed the formation of an approximately 10 μm thick severe plastic deformation (SPD) layer after UNSM treatment. After nitriding at 700 °C and 800 °C, a compound layer consisting of an approximately 0.2 μm and 1.9 μm thick nitride layer was observed in UNSM-treated Ti6Al4V alloy, which exhibits a nearly two-fold increase in nitride layer thickness as compared with the un-treated sample. This suggests that the nitrogen adsorption and the reaction capability are enhanced in the UNSM-treated Ti6Al4V alloy. This enhancement can be attributed to the high density dislocations and grain boundaries introduced by UNSM that serve as efficient diffusivity channels for interstitial gaseous atoms.
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Montavon, G., and C. Coddet. "Modification of Ceramic Thermal Spray Deposit Microstructure Implementing Laser Treatment." In ITSC2001, edited by Christopher C. Berndt, Khiam A. Khor, and Erich F. Lugscheider. ASM International, 2001. http://dx.doi.org/10.31399/asm.cp.itsc2001p1195.
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Abstract Microstructural features such as cracks, pores and delaminations are known to significantly affect the properties of thermal spray ceramic coatings. As an example, tensile properties depend mostly on the size, the shape and on the degree of clustering of pores since highly clustered porosity generates regions of poor mechanical properties from where cracks easily propagate through the entire volume. Another example concerns the corrosion resistance of coated components which is significantly degraded when pores are connected. To circumvent such disadvantages, several post-treatments may be implemented. The most commonly used is sealing of pores by impregnation using either low melting temperature metallic alloys or organic materials. In addition to be a costly additional step to the deposit manufacturing process, the coating working temperature limit is significantly reduced. Therefore, numerous works along the twenty past years have been devoted to find ways to densify ceramic coatings. Among these treatments, the use of high energy laser beams was very often considered. This paper aims to bring a contribution to those efforts by presenting results concerning the laser treatment of zirconia thermal spray coatings.
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Kim, J. H., B. G. Seong, J. H. Ahn, and K. H. Baik. "Nozzle Modification for Property Improvement of Arc Spray-formed Steel Tools." In ITSC2006, edited by B. R. Marple, M. M. Hyland, Y. C. Lau, R. S. Lima, and J. Voyer. ASM International, 2006. http://dx.doi.org/10.31399/asm.cp.itsc2006p1217.
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Abstract Modification of the nozzle of the arc spray equipment was attempted in order to reduce microstructural defects of the spray-formed steel shells since these defects mainly degrade the overall properties of the spray-formed tools. Based on the in-flight particle analysis, a new nozzle design of a gas shrouding concept was proposed. Effects of design factors such as nozzle dimensions and process conditions was investigated by using statistical analysis methods. The results demonstrated that the oxidation of the spray-formed steel shells can be reduced to the one-third levels of the original ones with an optimized design.
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MANOHARAN, NITHINKUMAR, and SUHASINI GURURAJA. "EFFECT OF CONTROLLED LOCAL MICROSTRUCTURAL MODIFICATION OF GLASS FIBER EPOXY COMPOSITES ON PROGRESSIVE DAMAGE PROPAGATION UNDER TENSILE LOADING." In Proceedings for the American Society for Composites-Thirty Seventh Technical Conference. Destech Publications, Inc., 2022. http://dx.doi.org/10.12783/asc37/36440.
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Advanced composite materials are defined by hierarchical, heterogeneous, and anisotropic behavior, resulting in complex, multi-scale progressive damage mechanisms, making failure predictions even under simple loading a challenging task. With the widespread usage of polymer composites for structural applications, holes, notches, and other geometric features are often needed for assembly and other functional requirements necessitating improvements to the local architecture around the holes to alleviate associated stress concentration effects. Multiwalled carbon nanotubes (MW-CNTs) when incorporated with epoxy matrix have shown to increase the open-hole tensile (OHT) strength of unidirectional glass fiber reinforced plastic (UD-GFRP) laminates by altering the inherent damage mechanisms. To assess the incipience of damage in MW-CNT modified UD-GFRP laminates, X-ray microcomputed tomography (CT) of the specimen before and after failure have been carried out in the current work. Future work is ongoing to perform in situ tensile testing assisted with X-ray micro-CT to have a better understanding of damage evolution in the specimens.
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Robbins, Joshua, and Pavel M. Chaplya. "Modeling of Nonlinear Material Behavior in Microstructurally Engineered Ferroelectric Ceramics." In ASME 2007 International Mechanical Engineering Congress and Exposition. ASMEDC, 2007. http://dx.doi.org/10.1115/imece2007-43706.
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Ferroelectric ceramics can be tailored at the microscale to have an ordered arrangement of crystal axes. Such grain-oriented ceramics can exhibit material properties far superior to conventional ceramics with random microstructure. A microstructurally based numerical model has been developed that describes the 3D non-linear behavior of ferroelectric ceramics. The model resolves the polycrystalline structure directly in the topology of the problem domain. The developed model is used to predict the effect of microstructural modifications on material behavior. In particular, we examine the internal residual stress after poling for idealized configurations of random and grain-oriented microstructures. The results indicate that a grain-ordered microstructure produces a significant increase in remanent polarization without detriment to internal residual stress.
Raporty organizacyjne na temat "Microstructural modification"
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Noell, Philip, Philip Noell, Philip Noell, et al. Microstructural Modification and Healing of Additively Manufactured Parts by Electropulsing. Office of Scientific and Technical Information (OSTI), 2019. http://dx.doi.org/10.2172/1570883.
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Stubbins, James, Brent Heuser, Peter Hosemann, and Xiang Liu. Fundamental Studies of Irradiation-Induced Modifications in Microstructural Evolution and Mechanical Properties of Advanced Alloys. Office of Scientific and Technical Information (OSTI), 2018. http://dx.doi.org/10.2172/1434640.
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