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Zhong, Zhen Chen. "Aluminium-based nanophase composites." Thesis, University of Cambridge, 1997. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.627138.
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Davies, Christopher Huw John. "Production of aluminium matrix composites." Thesis, Imperial College London, 1991. http://hdl.handle.net/10044/1/46737.
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Breban, Philippe. "Composites aluminium fibres de carbone obtenus par filage." Châtenay-Malabry, Ecole centrale de Paris, 1990. http://www.theses.fr/1990ECAP0130.
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La plupart des composites à matrice métalliques étudiés à l'heure actuelle sont élaborés par trois technologies principales, dont le coût relativement élevé limite les domaines d'utilisation. Pour palier cet inconvénient, nous avons travaillé à mettre au point un procédé de cofilage en phase solide. L’évolution du procédé nous a permis de résoudre les problèmes d'imprégnation du renfort par la matrice. Dans le cadre de l'optimisation des étapes de fabrication, nous avons étudié l'influence des paramètres suivants sur le comportement et les mécanismes d'endommagement du matériau: longueur des fibres, orientation du renfort et fraction volumique locale. Pour cela nous avons développé une démarche de type micro-macro fondée sur la théorie d'inclusion équivalente d'Eshelby. Nous modélisons ainsi l'influence de la microstructure sur les caractéristiques élastiques, les coefficients de dilatation et la surface seuil d'écoulement. Des calculs par éléments finis sur cellules de base à trois phases complète cette approche. Nous regardons l'influence de la répartition des fibres sur le développement de la plasticité locale. Une configuration de fibres proches de leurs voisines a un rôle prépondérant sur la propagation de l'endommagement qui se produit en tête de fibre. Nous proposons un critère analytique d'initiation de cet endommagement qui prend en compte la distribution de fraction volumique locale dans le matériau. Les résultats sont comparés à des essais de traction dans l'enceinte du microscope électronique à balayage, ou nous pouvons suivre les différentes étapes du processus de rupture. L’outil analytique développé est intégré dans une démarche originale de détermination d'une statistique d'endommagement pour une structure. Nous pouvons, ainsi, donner localement la probabilité d'endommagement d'un volume de composite en fonction de l'observation de ses distributions de microstructure, et du chargement
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Zulfia, Anne. "Pressureless infiltration of aluminium matrix composites." Thesis, University of Sheffield, 2000. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.484253.
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Matthews, Stephen John. "Cavitation erosion of aluminium alloys, aluminium alloy/ceramic composites and ceramics." Thesis, Coventry University, 1993. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.317927.
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Mercier, Sylvie. "Réactivité interfaciale de systèmes aluminium-fibres de carbone et aluminium-fibres céramique." Mulhouse, 1994. http://www.theses.fr/1994MULH0303.
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L'objectif de l'étude est d'apporter une contribution à la compréhension des phénomènes interfaciaux qui interviennent lors de l'élaboration des matériaux composites à renfort fibreux et à matrice aluminium. Les renforts choisis pour cette étude ont été des fibres de carbone, des fibres de carbone protégées, et des fibres à base de carbure de silicium. Ces fibres sous forme de tissu ont été recouvertes d'aluminium par dépôt physique en phase vapeur. Les matériaux ainsi obtenus ont subi des traitements thermiques dans un réacteur couple à un spectromètre de masse. L'existence de réactions entre certains gaz produits par les fibres (CO, CO2) et l'aluminium lorsque la température est supérieure à 650°C a ainsi pu être mise en évidence. Ces réactions se produisent lors de la traversée du dépôt d'aluminium par les gaz issus des fibres et provoquent la formation de carbone d'aluminium. Le carbure d'aluminium est également formé par des réactions entre les espèces solides constituant les fibres et le métal. La quantité de carbure d'aluminium formé à l'interface fibre/métal lors des traitements thermiques a été déterminée par hydrolyse. Il a ainsi pu être montré que le carbure d'aluminium provient essentiellement des réactions entre les solides constituant les fibres et le métal. L'efficacité de divers recouvrements contre la formation de carbure d'aluminium a aussi été étudiée.
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Chamroune, Nabil. "Matériaux composites Aluminium/Carbone : architecture spécifique et propriétés thermiques adaptatives." Thesis, Bordeaux, 2018. http://www.theses.fr/2018BORD0140/document.
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Les matériaux composites à matrice métallique (CMM) sont actuellement étudiés pour être utilisés dans de nombreux domaines d’application. L’une des applications potentielles concerne leur utilisation en tant que drain thermique pour les modules de puissance. Pour cette application, deux conditions sont requises : une conductivité thermique (CT) élevée pour évacuer la chaleur générée par la puce électronique et un coefficient d’expansion thermique (CTE) proche du substrat céramique (2-8×10-6 /K) utilisé dans le module de puissance.Ainsi des matériaux composites à matrice aluminium (Al : CT de 217 W/m.K et CTE de 24×10-6 /K) et à renfort plaquette de graphite (GF : CT de 1000 W/m.K et CTE de -1×10-6 /K dans le plan de la plaquette) ont été élaborés. Ces matériaux composites ont été fabriqués par Métallurgie des Poudres (MP) conventionnelle mais aussi par un procédé original nommé Flake Powder Metallurgy (FPM). Ce procédé, qui consiste à utiliser une poudre métallique à morphologie plaquette, a permis d’optimiser l’orientation des renforts plaquette dans un plan perpendiculaire à la direction de densification sous l’action d’une pression uniaxiale. De plus, ce procédé a permis d’obtenir une meilleure adhésion entre la matrice et le renfort comparé aux matériaux composites élaborés par MP conventionnelle. Cela a abouti à une amélioration de la CT qui est passée de 400 W/m.K à 450 W/m.K pour un taux de renfort de 50%vol. Néanmoins, concernant la dilatation thermique, des CTE de 21,8×10-6 /K et 21,7×10-6 /K ont été obtenus par MP et FPM respectivement, ce qui est incompatible avec l’application visée.Pour surmonter cette problématique, des matériaux composites à renfort multiple ont été élaborés par frittage en phase liquide. Ainsi des fibres de carbone (FC) ont été rajoutées à l’aluminium et aux plaquettes de graphite. L’ajout de ce second renfort au graphite a permis de diminuer de manière importante le CTE des composites Al/(GF+FC) avec une faible proportion en FC tout en maintenant une haute CT. De plus les matériaux composites Al/(GF+FC) présentent des CTE nettement inférieurs aux composites Al/FC avec un %vol. de FC équivalent. Ainsi des matériaux composites Al/(GF+FC) ont été élaborés par frittage en phase liquide permettant d’obtenir une CT de 400 W/m.K (comparable à la CT du cuivre) et un CTE de 8×10-6 /K (comparable au CTE de l’alumine). De plus la légèreté de l’aluminium confère aux matériaux composites Al/C une faible densité (d=2,4). Par conséquent, les matériaux développés dans cette étude sont prometteur en tant que drain thermique léger, notamment dans le domaine de l’électronique embarquéeMany carbon/metal composites are currently used in several applications. One of them concerns their use as heat sinks in microelectronics. Concerning this application, two conditions are required: a high thermal conductivity (TC) in order to evacuate the heat generated by the electronic chip and a coefficient of thermal expansion (CTE) similar to the used material type of the electronic device (2-8×10-6 /K).Therefore, graphite flakes (GF; TC: 1000 W/m.K and CTE: -1×10-6 /K in the graphite plane) reinforced aluminum matrix (Al; TC: 217 W/m.K and CTE: 25×10-6 /K) composites were fabricated. These composite materials were fabricated by Powder Metallurgy (PM) and Flake Powder Metallurgy (FPM). This process, which consist to use a flattened metallic powder, helped to improve the in-plane orientation (perpendicular to the pressure direction) of GF under uniaxial pressure. Moreover, this process provided a better Al-C interface thanks to a planar contact between the matrix and the reinforcements. This resulted in an improvement of the CT from 400 W/m.K to 450 W/m.K for a reinforcement content of 50 vol.%. Nevertheless, regarding thermal dilation, CTEs of 21.8×10-6 /K and 21.7×10-6 /K were obtained by MP and FPM respectively, which is incompatible with the intended application.To overcome this problem, composite materials with multiple reinforcement were developed by solid-liquid phase sintering. Then, carbon fibers (CF) have been added to aluminum and graphite flakes. The addition of CF to GF reinforcement reduced significantly the CTE of the Al/(GF+CF) composites with a small proportion of CF, while preserving a high TC. In addition, the Al/(GF+FC) composite materials have significantly lower CTEs than the Al/CF composites with a equivalent vol.% of CF. Therefore, Al/(GF+CF) composite materials were developed by solid-liquid phase sintering to obtain a TC of 400 W/m.K (comparable to the TC of copper) and a CTE of 8×10-6 /K (comparable to the CTE of alumina). In addition, the lightweight of aluminum gives composite materials Al/C a low density (d = 2.4 g/cm3). Therefore, the composite materials developed in this study are promising as a lightweight heat sink in microelectronic industries
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Al-Jumaili, Omar Saad Salih. "Investigation of friction stir welding of aluminium alloy and aluminium matrix composites." Thesis, University of Nottingham, 2018. http://eprints.nottingham.ac.uk/55637/.
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Friction stir welding (FSW) is an upgraded version of the conventional friction welding process, and it is considered the latest development and the most important one during the past two decades in the welding of metals. The dependence of FSW on friction and plastic work as a heat source precludes the melting in the workpiece and leads to avoiding many of the difficulties arising from the change in the state of the material, such as defects, distortion and residual stresses, which often happen in conventional welding processes. FSW gained significant attention as a solid-state welding process of aluminium alloys, but now there is a need to extend its application to advanced materials such as metal matrix composites (MMCs). However, the process has always represented a challenge owing to the complexity of microstructural development and the associated number of process parameters to take into consideration. This thesis investigates the feasibility of welding two new advanced aluminium matrix composites (AMCs), AA 6092/SiC/17.5p-T6 and AA 6061B/SiC/20p-T1 by FSW for the first time. Also, aluminium alloy AA6082-T6 has been investigated as base-line material to specify the benefit, drawback, and FSW window. Experiment analyses were conducted to evaluate the influence of FSW parameters, including tool rotation and traverse speeds on the quality of weldments. Weld joints were characterised in terms of thermal history, metallurgical behaviour, mechanical properties, and residual stresses. The metallurgical characterisations have been done by optical, scanning electron microscopy (SEM), electron backscattered diffraction (EBSD), transmission electron microscopy (TEM), and energy dispersive X-ray spectroscopy (EDS). Microhardness, tensile, and low-cycle fatigue (LCF) test with the axial total strain-amplitude control mode R=ε_min⁄(ε_max=-1) were used for evaluating the mechanical properties. The results showed that the generated peak temperature in the welding joints is affected more significantly by the rotating tool speed, while the exposure time and subsequent cooling rate are controlled by tool traverse speed. The microstructure of nugget zone (NZ) exhibits an elliptical shape with a substantial grain refinement resulted from continuous dynamic recrystallisation (CDR) process with an increase in the fraction of high angle grain boundaries (HAGBs). The evolved grain size was greatly influenced by weld pitch as the ratio between tool traverse speed to tool rotation speed, which is a key parameter to control the amount of heat input, exposure time and cooling rate. In addition, in the case of AMCs more homogeneous distribution of reinforcement particles (SiC) coupled with particle refinement were formed in the NZ. The cross-weld microhardness profile revealed a significant difference in microhardness among the base metals, heat affected zone (HAZ), thermo-mechanically affected zone (TMAZ), and NZ in the case of AA 6082 and AMC (AA 6092/SiC/17.5p), as they depend on the strengthening precipitate. Meanwhile, the hardness profile of AMC (AA 6061B/SiC/20p) FSW joints showed that there is no difference in the measured hardness between the welding zone and base materials because the welded joints are exposed to thermal history similar to the initial heat treatment condition of the base metal, T1, cooled from an elevated temperature shaping process and naturally aged. The tensile strength of AA6082, and AMC (AA 6092/SiC/17.5p) cross-weld FSW specimens was found to be lower than their base metals with a joint efficiency (the ratio of the tensile strength of joint to the tensile strength of base metal) of about 71 and 75 %, respectively. While for SAMC (AA 6061B/SiC/20p) FSW joints it is reached 108 % of that of the base metal. The low-cycle fatigue results indicate that the fatigue life of the cross-weld joints varies with grain size in the NZ, and it is always lower than that of the base metal. A significant improvement in fatigue life is found to be related to the finer equiaxed grains dominated by HAGBs in the NZ, as well as, to less gradient in the grain size of the cross-weld. Residual stresses are significant concerns associated with the welding process, as it can combine with applied stresses, which may lead to the reduction of structural properties. The result of residual stress measurement by neutron diffraction techniques exhibited a typical ''M'' profile, which indicates that compressive and tensile residual stress existed in the base metal and welding zone, respectively. This has not only provided an improved understanding of residual stresses in FSW joints but also has contributed to the validation of 3D fully coupled thermo-mechanical finite element (FE) model, which has been developed based on Coupled Eulerian-Lagrangian (CEL) technique. The model is also used to predict the thermal history and material flow in the FSW of aluminium alloy AA6082. The numerical results showed a good agreement with the experimental results.
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Furness, Justin Albert George. "Thermal cycling creep of aluminium based composites." Thesis, University of Cambridge, 1991. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.239618.
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Wilson, Scott. "The tribological behaviour of aluminium matrix composites." Doctoral thesis, University of Cape Town, 1993. http://hdl.handle.net/11427/21799.
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Metal matrix composites consisting of 6061 and 2014 aluminium alloys, reinforced with 10%, 15% and 20% alumina particulates and a 6061 alloy reinforced with 20% SiC particulates, have been characterised in terms of their behaviour under various tribological conditions. In abrasive environments, the wear behaviour of each composite is dominated by their ability to resist indentation by hard particles. Abrasion against fine grit particles leads to a reduced load per abrasive particle and a correspondingly significant reduction in wear loss. Reciprocating sliding wear tests, conducted in an aqueous environment and against hardened steel counterfaces, displayed composite wear rates that were up to three orders of magnitude below those of their monolithic alloys. This is attributed to the increased resistance to surface shear provided by the reinforcing particulates themselves and their constraining effects on the matrix. The particulates become load bearing and protect the matrix by reducing the metal to counterface adhesive wear. However, the counterface wear increases due to the interaction with the hard reinforcements. Transmission electron microscopy of the worn composites reveal the formation of a transfer layer and subsurface dislocation structures which are similar to those found in metals subjected to low amplitude fatigue. In contrast to the results for abrasive and sliding wear, the composites show increasingly inferior cavitation and solid particle erosion resistances with increasing volume fractions of particulates. This depreciating effect was especially evident for particle erosion and can be related to the inability of metal matrix composites to accommodate the increments of strain which accompany erosive processes. The mechanisms responsible for the various performances have been studied by scanning electron microscopy, optical microscopy and transmission electron microscopy. An attempt is made to reconcile the steady state wear rates of the reinforced and unreinforced alloys with their observed wear modes, microstructures and bulk mechanical behaviour.
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Durrant, George. "The forging of saffil fibre reinforced aluminium." Thesis, University of Bath, 1992. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.317301.
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Hunt, Edward Patrick. "Structure property relationships in fibre reinforced aluminium laminates and SiC particulate aluminium composites." Thesis, University of Southampton, 1991. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.315434.
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Downes, Terry James. "The mechanical properties of aluminium-lithium based composites." Thesis, University of Cambridge, 1993. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.281894.
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Davenport, Simon Bruce. "Fatigue response of fibre reinforced aluminium-lithium laminates." Thesis, University of Southampton, 1995. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.261787.
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Williams, J. R. "Corrosion of aluminium-copper-magnesium metal matrix composites." Thesis, University of Nottingham, 1994. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.239852.
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Walker, John Christopher. "Lubricated sliding wear of some aluminium alloy composites." Thesis, University of Sheffield, 2006. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.434551.
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Musson, Nicholas John. "The squeeze casting of aluminium alloys and composites." Thesis, University of Southampton, 1990. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.293609.
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Couturier, Laurent. "Comportement mécanique de matériaux composites à matrice aluminium." Compiègne, 1998. http://www.theses.fr/1998COMP1103.
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L'utilisation dans les industries automobile et aéronautique de composites à matrice aluminium correspond à un potentiel important. Ces composites constitués d'une matrice d'alliage d'aluminium renforcée par des céramiques ont montré leur efficacité dans le remplacement de matériaux de densité plus élevée. La thèse a porté sur des composites AS10U3NG+10%SiCp, AS9G+20%SiCp, 2618+20%AI203p, AS7G+20%AI203fc, AS12UNG+200/0AI2O3fc et sur un alliage d'aluminium non renforcé AS10U3NG, élaborés suivant plusieurs techniques de fonderie. Elle a aborde les points suivants : - comparaison des caractéristiques monotones - usinage par outil diamant des CMA - évolution des contraintes résiduelles d'usinage et de grenaillage mesurées par la méthode du perçage incrémental - résistance à la fatigue endurance en flexion quatre points (éprouvettes grenaillées et non grenaillées, analyse des facies de rupture et sites d'amorçage) - suivi de l'endommagement par des méthodes non destructives telles que l'émission acoustique, la cartographie ultrasonore, l'atténuation ultrasonore en onde de surface et la variation de raideur, - comportement tribologique sur trois différents tribomètres correspondant à des essais de frottement sphère plan, ou cylindre plan et des essais de résistance à l'abrasion - calcul de durée de vie en fatigue multiaxiale avec prise en compte des contraintes résiduelles sur d'autre matériaux tels que des aciers. L'étude s'est concentrée sur le rôle de la microstructure et de celui des renforts en liaison avec les caractéristiques monotones, pour comprendre le comportement de ces matériaux composites vis à vis des différents essais réalisés. Les conclusions obtenues qui s'appuient sur les nombreux résultats de la recherche permettent d'apporter de multiples renseignements sur le comportement mécanique global de ces matériaux et devraient permettre d'accroitre leur domaine d'utilisation. Le mémoire indique un nombre important d'axes de recherche qui devraient être porteur dans l'avenir.
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Bushby, Roger Stanley. "Joining aluminium-based composites using diffusion bonding techniques." Thesis, University of Bath, 1993. https://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.331934.
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Silva, Cauê Corrêa da. "Manufacturing and characterization of aluminium-nickel matrix composites." reponame:Repositório Institucional da UFSC, 2015. https://repositorio.ufsc.br/xmlui/handle/123456789/162713.
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Dissertação (mestrado) - Universidade Federal de Santa Catarina, Centro Tecnológico, Programa de Pós-Graduação em Engenharia Mecânica, Florianópolis, 2015.Made available in DSpace on 2016-05-24T17:40:40Z (GMT). No. of bitstreams: 1 338916.pdf: 1608467 bytes, checksum: 23dec638e6d54767a7815bbbc05e726e (MD5) Previous issue date: 2015
Abtsract : The present work describes the designing of a manufacturing process for the production of aluminum matrix composites reinforced with carbon fibers. The matrix was chosen to be an interlayering of aluminum foils and nickel mesh stripes, cold rolled with 70% of thickness reduction, being then submitted to different heat treatments, of which immersion in pure aluminum melt was found to be the most promising. Microstructure and composition of the samples were analyzed with scanning electron microscopy, energy-dispersive X-ray spectroscopy, X-ray diffractography and microhardness test, whose results showed the presence of remaining nickel and intermetallic compounds formed during the processing, namely Ni2Al3 and NiAl, agreeing with studies on reactive diffusion found in the literature. Furthermore, composites were produced by incorporating nickel-coated carbon fibers to the manufacturing process, being evaluated the effect of the fibers addition to the material with scanning electron microscopy, energy-dispersive Xray spectroscopy, X-ray diffractography and fiber content estimation via image binarization. Intermetallic phases were also present in the microstructure of the composites, nevertheless in smaller extent and in an aluminum matrix. Bond between matrix and fibers was found to be strong, since no fiber pull out took place. Performed fiber content analysis showed that the optimum fiber volume content is between 15% and 40%. Mechanical properties of both without and with fibers materials were assessed through 4-point bending tests, having theirfracture surface analyzed afterwards.
O presente trabalho descreve o desenvolvimento de um processo de fabricação para a produção de compósitos de matriz de alumÃnio reforçados com fibras de carbono. O material escolhido para a matriz era constituÃdo por camadas intercaladas de folhas de alumÃnio e malha de nÃquel, laminadas a frio com 70% de redução de espessura, sendo então submetidos a diferentes tratamentos térmicos, dentre os quais imersão em fundido de alumÃnio mostrou-se o mais promissor. A microestrutura e a composição das amostras foram analisadas com microscopia eletrônica de varredura, espectroscopia dispersiva de raios-X, difratografia de raios-X e testes de microdureza, cujos resultados mostraram a presença de nÃquel remanescente e compostos intermetálicos, Ni2Al3 e NiAl, coincidindo com estudos sobre difusão reativa encontrados na literatura. Além disso, compósitos foram produzidos através da incorporação de fibras de carbono revestidas com nÃquel ao processo de fabricação, sendo avaliados os efeitos da adição de fibras ao material com microscopia eletrônica de varredura, espectroscopia dispersiva de raios-X, difratografia de raios-X e estimativa do teor de fibras através de binarização de imagens. Fases intermetálicas também estavam presentes na microestrutura do compósito, entretanto em menor quantidade e em uma matriz de alumÃnio. A adesão entre matriz e fibras foi avaliada como sendo alta, visto que não ocorrou o fenômeno de pull out das fibras. As análises de teor de fibra mostraram que o volume de fibras ótimo encontra-se entre 15% e 40%. Tanto propriedades mecânicas do material sem fibra, quanto do com fibra, foram aferidos com teste de flexão em 4 pontos, posteriormente tendo sua superfÃcie de fratura analisada.
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Silva, Cauê Corrêa da. "Manufacturing and characterization of aluminium-nickel matrix composites." reponame:Repositório Institucional da UFSC, 2015. https://repositorio.ufsc.br/xmlui/handle/123456789/169520.
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Dissertação (mestrado) - Universidade Federal de Santa Catarina, Centro Tecnológico, Programa de Pós-Graduação em Engenharia Mecânica, Florianópolis, 2015.Made available in DSpace on 2016-10-19T13:04:45Z (GMT). No. of bitstreams: 1 338916.pdf: 1608467 bytes, checksum: 23dec638e6d54767a7815bbbc05e726e (MD5) Previous issue date: 2015
Abtsract : The present work describes the designing of a manufacturing process for the production of aluminum matrix composites reinforced with carbon fibers. The matrix was chosen to be an interlayering of aluminum foils and nickel mesh stripes, cold rolled with 70% of thickness reduction, being then submitted to different heat treatments, of which immersion in pure aluminum melt was found to be the most promising. Microstructure and composition of the samples were analyzed with scanning electron microscopy, energy-dispersive X-ray spectroscopy, X-ray diffractography and microhardness test, whose results showed the presence of remaining nickel and intermetallic compounds formed during the processing, namely Ni2Al3 and NiAl, agreeing with studies on reactive diffusion found in the literature. Furthermore, composites were produced by incorporating nickel-coated carbon fibers to the manufacturing process, being evaluated the effect of the fibers addition to the material with scanning electron microscopy, energy-dispersive Xray spectroscopy, X-ray diffractography and fiber content estimation via image binarization. Intermetallic phases were also present in the microstructure of the composites, nevertheless in smaller extent and in an aluminum matrix. Bond between matrix and fibers was found to be strong, since no fiber pull out took place. Performed fiber content analysis showed that the optimum fiber volume content is between 15% and 40%. Mechanical properties of both without and with fibers materials were assessed through 4-point bending tests, having theirfracture surface analyzed afterwards.
O presente trabalho descreve o desenvolvimento de um processo de fabricação para a produção de compósitos de matriz de alumínio reforçados com fibras de carbono. O material escolhido para a matriz era constituído por camadas intercaladas de folhas de alumínio e malha de níquel, laminadas a frio com 70% de redução de espessura, sendo então submetidos a diferentes tratamentos térmicos, dentre os quais imersão em fundido de alumínio mostrou-se o mais promissor. A microestrutura e a composição das amostras foram analisadas com microscopia eletrônica de varredura, espectroscopia dispersiva de raios-X, difratografia de raios-X e testes de microdureza, cujos resultados mostraram a presença de níquel remanescente e compostos intermetálicos, Ni2Al3 e NiAl, coincidindo com estudos sobre difusão reativa encontrados na literatura. Além disso, compósitos foram produzidos através da incorporação de fibras de carbono revestidas com níquel ao processo de fabricação, sendo avaliados os efeitos da adição de fibras ao material com microscopia eletrônica de varredura, espectroscopia dispersiva de raios-X, difratografia de raios-X e estimativa do teor de fibras através de binarização de imagens. Fases intermetálicas também estavam presentes na microestrutura do compósito, entretanto em menor quantidade e em uma matriz de alumínio. A adesão entre matriz e fibras foi avaliada como sendo alta, visto que não ocorrou o fenômeno de pull out das fibras. As análises de teor de fibra mostraram que o volume de fibras ótimo encontra-se entre 15% e 40%. Tanto propriedades mecânicas do material sem fibra, quanto do com fibra, foram aferidos com teste de flexão em 4 pontos, posteriormente tendo sua superfície de fratura analisada.
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Coleman, Sarah L. "The corrosion of metal matrix composites." Thesis, University of Bath, 1991. https://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.303434.
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Shahani, Ravi Arjan. "Microstructural development during thermomechanical processing of aluminium-based composites." Thesis, University of Cambridge, 1991. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.239037.
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Lalet, Grégory. "Composites aluminium/fibres de carbone pour l'électronique de puissance." Phd thesis, Université Sciences et Technologies - Bordeaux I, 2010. http://tel.archives-ouvertes.fr/tel-00538480.
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L'étude a pour objectif l'amélioration de la fiabilité des assemblages électroniques à travers la mise en œuvre de drains composites aluminium/fibres de carbone. Le travail a consisté à 1) modéliser, par la méthode des éléments finis, l'influence des propriétés thermiques et mécaniques du matériau de semelle sur l'assemblage életronique ; 2) élaborer (par frittage sous charge uniaxiale, frittage flash et extrusion à chaud) des matériaux composites aluminium/fibres de carbone ; et 3) lier les microstructures observées aux paramètres des procédés d'élaboration ainsi qu'aux propriétés thermiques et mécaniques mesurées.
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Idris, Maizlinda Izwana Materials Science & Engineering Faculty of Science UNSW. "Structural integrity of carbon fibre/aluminium foam sandwich composites." Awarded By:University of New South Wales. Materials Science & Engineering, 2010. http://handle.unsw.edu.au/1959.4/44722.
Full textAbstract:
This thesis focuses on closed-cell aluminium foams (ALPORAS and ALULIGHT) and on sandwich panels comprising these foams laminated with 2/2 twill carbon fibre (MTM56/0300) skins. The thesis experimentally and analytically investigates the response of foam-only panels (ALPORAS) to indentation with various indenter sizes and shapes; and also studies the behaviour of sandwich panels to contact damage caused quasi-statically or by impact. Quasi??static uniaxial compression testing is used to determine the mechanical properties of the foams (ALPORAS and ALULIGHT). It is revealed that the plastic collapse strength (σ* pl) obtained from the stress??strain curves is lower than the values predicted by the Gibson-Ashby theoretical model. This phenomenon is explained by the fact that the aluminium foams tested are imperfect, non-homogeneous and non-isotropic, and show a distinct cell elongation. Whereas, the Gibson-Ashby theoretical model was based on the finite element method applied to the response of a unit tetrakaidecahedral closed cell having flat faces. The experimental work shows that the deformation of the foam-only panels to indentation is caused by progressive crushing of the cell bands and by shearing and tearing of the cell walls. This thesis presents new analytical models for the response of the foam-only panels and estimates the applied deformation load in all types of indentation. By fitting the experimental load-displacement curves, the shear strength (τ* pl) and the tear energy (γ) are deduced. Compared to the literature, more consistent results are obtained for the shear strength (τ * pl) and the tear energy (γ) from all types of indentation. It is also suggested to determine (τ * pl) and (γ) through indentations with long punches (FEP and LCP), instead of hemi-spherical or cylindrical indenters, because indentation on enclosed areas shows some indenter size dependence. It is concluded that thinner panels are not suitable for the determination of the tear energy (γ) since the densification of the foam is achieved before the tear resistance is fully engaged. Another objective of this thesis is to study the response of sandwich panels comprising a closed??cell aluminium foam core and laminated with carbon fibre skin to quasi-static and impact local damage. Special attention is paid to the residual (remnant) strength in bending of the already indented sandwich panels (quasi-statically or by impact) up to the failure point. The remnant strength in bending is determined by carrying out four point bending strength tests. The local damage is located on either the compressive or on the tensile side of the sandwich panels. Thus, the capacity of the panels to resist transverse loads after they have been locally damaged at contact is investigated. The contact damage on the sandwich panels is experimentally simulated using spherical indenters. The quasi-static indentation is carried out at a low constant velocity (0.5mm/min) ?? the induced contact damage is found to be independent on the sample thickness but dependent on the indenter diameter. On the contrary, the impact test indicates velocity-dependence of the failure mode of the sandwich panel (i.e. skin breakage or punch through) which is found from the load-displacement curves. The results reveal that there is a correlation between the area of the contact damage and the remnant strength, and that the use of metal foam cores leads to high contact damage resilience of composite structures.
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Svendsen, Lena. "On the processing of aluminium-C/TiC/TiB₂ composites /." Stockholm, 1998. http://www.lib.kth.se/abs98/sven0123.pdf.
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Knowles, David Michael. "Fatigue and fracture behaviour of aluminium-lithium based composites." Thesis, University of Cambridge, 1991. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.387114.
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Kang, Hyung-gu. "Locally reinforced squeeze cast aluminium alloy metal matrix composites." Thesis, University of Oxford, 1995. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.294391.
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Ison, Stephen John. "Interfacial reactions between PbO-rich glasses and aluminium composites." Thesis, University of Warwick, 2000. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.364605.
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Manurung, Posman. "Microstructural design and characterisation of alumina/aluminium titanate composites." Thesis, Curtin University, 2001. http://hdl.handle.net/20.500.11937/2208.
Full textAbstract:
A new but relatively simple processing study was conducted to investigate the microstructure-property relationships of alumina/aluminium titanate (AAT) composites. The objectives of this study were: (a) to develop a process for fabricating AAT and β-spodumene modified AAT composites using a solid-state reaction method and functionally-graded AAT using an infiltration technique, and (b) to evaluate the effects of dispersed aluminium titanate (AT) on the phase relations, microstructure and mechanical properties of alumina-based composites. The study has revealed that the processing procedures played an important rule in the microstructural development of AAT composites. The microstructure and properties of AAT composites have been found to be strongly influenced by the presence of dispersed AT. The phase relations in the AAT system have been characterised by x-ray diffraction (XRD) and neutron diffraction (ND). Rietveld analysis showed that the AT content increased in proportion with the amount of rutile added. The dynamic ND study showed that AT commenced to form at ~1310°C The presence of AT caused a reduction of hardness but an improvement in fracture toughness. In addition, the presence of AT hindered the processes or kinetics of sintering and densification. The use of β-spodumene has been investigated as a liquid-phase-sintering aid for the densification of AAT composites. XRD, ND, differential thermal analysis (DTA), scanning electron microscopy (SEM), transmission electron microscopy (TEM) and Vickers indentation were used to characterise the effect of β-spodumene on the phase relations, densification, microstructure and mechanical properties of AAT composites. The presence of β-spodumene was found to have a profound influence on the phase relations, densification, microstructure and properties of AAT composites.The addition of β-spodumene caused a small reduction of AT content and a commensurate increase of alumina phase. Functionally-graded AAT composites have been successfully synthesised through infiltration of porous alumina preform with a solution containing TiCl4. The infiltration kinetics of liquid into porous alumina preform has also been investigated and modelled. It was found that the infiltration rate equation proposed by Washburn was proven to be suitable for describing the kinetics of infiltration in terms of preform sintering temperature, viscosity, and multiple infiltrations. The influence of applied pressure was consistent with the model proposed by Travitzky and Shlayen, where the applied pressure enhanced the rate of infiltration. Pre-sintering of alumina preform at 900, 1000 and 1100°C for 2 h resulted in different rates of infiltration which may be attributed to a varying degree in tortuosity of the pore channels. The graded composition character of functionally-graded AAT composites has been determined by XRD and grazing incidence synchrotron diffraction (GISRD). Graded compositions from Rietveld refinement analysis showed that the concentration of AT decreased with depth. In contrast, the α-A12O3 content increased with depth. Microstructural examination by SEM showed that the content of AT grains was the most abundant near the surface and decreased gradually with an increase in depth. The hardness results showed that FGM had a soft graded-region (AT rich) but hard non-graded alumina region.The lower hardness in the graded region can be attributed to the presence of intrinsically soft AT phase. The presence of graded AT caused a considerable improvement in damage tolerance. The isothermal decomposition of AT at 1100°C both in air and vacuum has been studied. Both ex-situ and in-situ studies have been conducted to examine the effect of environment on the decomposition behaviour of AT. The addition of MgO was effective in enhancing the thermal stability of AT against decomposition both in air and in vacuum.
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Manurung, Posman. "Microstructural design and characterisation of alumina/aluminium titanate composites." Curtin University of Technology, Department of Applied Physics, 2001. http://espace.library.curtin.edu.au:80/R/?func=dbin-jump-full&object_id=13269.
Full textAbstract:
A new but relatively simple processing study was conducted to investigate the microstructure-property relationships of alumina/aluminium titanate (AAT) composites. The objectives of this study were: (a) to develop a process for fabricating AAT and β-spodumene modified AAT composites using a solid-state reaction method and functionally-graded AAT using an infiltration technique, and (b) to evaluate the effects of dispersed aluminium titanate (AT) on the phase relations, microstructure and mechanical properties of alumina-based composites. The study has revealed that the processing procedures played an important rule in the microstructural development of AAT composites. The microstructure and properties of AAT composites have been found to be strongly influenced by the presence of dispersed AT. The phase relations in the AAT system have been characterised by x-ray diffraction (XRD) and neutron diffraction (ND). Rietveld analysis showed that the AT content increased in proportion with the amount of rutile added. The dynamic ND study showed that AT commenced to form at ~1310°C The presence of AT caused a reduction of hardness but an improvement in fracture toughness. In addition, the presence of AT hindered the processes or kinetics of sintering and densification. The use of β-spodumene has been investigated as a liquid-phase-sintering aid for the densification of AAT composites. XRD, ND, differential thermal analysis (DTA), scanning electron microscopy (SEM), transmission electron microscopy (TEM) and Vickers indentation were used to characterise the effect of β-spodumene on the phase relations, densification, microstructure and mechanical properties of AAT composites. The presence of β-spodumene was found to have a profound influence on the phase relations, densification, microstructure and properties of AAT composites.The addition of β-spodumene caused a small reduction of AT content and a commensurate increase of alumina phase. Functionally-graded AAT composites have been successfully synthesised through infiltration of porous alumina preform with a solution containing TiCl4. The infiltration kinetics of liquid into porous alumina preform has also been investigated and modelled. It was found that the infiltration rate equation proposed by Washburn was proven to be suitable for describing the kinetics of infiltration in terms of preform sintering temperature, viscosity, and multiple infiltrations. The influence of applied pressure was consistent with the model proposed by Travitzky and Shlayen, where the applied pressure enhanced the rate of infiltration. Pre-sintering of alumina preform at 900, 1000 and 1100°C for 2 h resulted in different rates of infiltration which may be attributed to a varying degree in tortuosity of the pore channels. The graded composition character of functionally-graded AAT composites has been determined by XRD and grazing incidence synchrotron diffraction (GISRD). Graded compositions from Rietveld refinement analysis showed that the concentration of AT decreased with depth. In contrast, the α-A12O3 content increased with depth. Microstructural examination by SEM showed that the content of AT grains was the most abundant near the surface and decreased gradually with an increase in depth. The hardness results showed that FGM had a soft graded-region (AT rich) but hard non-graded alumina region.
The lower hardness in the graded region can be attributed to the presence of intrinsically soft AT phase. The presence of graded AT caused a considerable improvement in damage tolerance. The isothermal decomposition of AT at 1100°C both in air and vacuum has been studied. Both ex-situ and in-situ studies have been conducted to examine the effect of environment on the decomposition behaviour of AT. The addition of MgO was effective in enhancing the thermal stability of AT against decomposition both in air and in vacuum.
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Perrin, Carl. "Wear of aluminium alloys and alluminium-based MMCs." Thesis, University of Sheffield, 1994. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.294216.
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Alhashmy, Hasan. "Fabrication of Aluminium Matrix Composites (AMCs) by Squeeze Casting Technique Using Carbon Fiber as Reinforcement." Thèse, Université d'Ottawa / University of Ottawa, 2012. http://hdl.handle.net/10393/23120.
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Composites have been developed with great success by the use of fiber reinforcements in metallic materials. Fiber reinforced metal matrices possess great potential to be the next generation of advanced composites offering many advantages compared to fiber reinforced polymers. Specific advantages include high temperature capability, superior environmental stability, better transverse modulus, shear and fatigue properties. Although many Metal Matrix Composites (MMCs) are attractive for use in different industrial applications, Aluminium Matrix Composites (AMCs) are the most used in advanced applications because they combine acceptable strength, low density, durability, machinability, availability, effectiveness and cost. The present study focuses on the fabrication of aluminium matrix composite plates by squeeze casting using plain weave carbon fiber preform (AS4 Hexcel) as reinforcement and a matrix of wrought aluminium alloy 1235-H19. The objective is to investigate the process feasibility and resulting materials properties such as hardness at macro- and micro-scale, impact and bend strength. The properties obtained are compared with those of 6061/1235-H19 aluminium plates that were manufactured under the same fabrication conditions. The effect of fiber volume fraction on the properties is also investigated. Furthermore, the characterization of the microstructure is done using Optical Microscopy (OM) and Scanning Electron Microscopy (SEM) in order to establish relationships between the quality of the fiber/aluminium interface bond and mechanical properties of the composites.
In conclusion, aluminium matrix composite laminate plates were successfully produced. The composites show a good chemical bond between the fiber and the aluminium matrix. This bond resulted from heterogeneous precipitation of aluminium carbides (Al4C3) at the interface between aluminium matrix and carbon fiber. The hardness at macro- and micro-scale of the composites increases by over 50% and the flexural modulus increases by about 55%. The toughness of the composite decreases due to the presence of brittle phases which can be improved by better oxidation prevention. Also, an optimal carbon volume fraction was observed that provides optimal properties including peak hardness, peak stiffness and peak toughness.
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Polley, Neal John. "Development of Al-Mgâ‚‚Si in situ composites." Thesis, Brunel University, 2003. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.274812.
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Johannesson, Birgir. "Internal stresses and the cyclic deformation of an aluminium matrix composite." Thesis, University of Surrey, 1992. http://epubs.surrey.ac.uk/843903/.
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The development of internal stresses in planar random Saffil fibre reinforced aluminium with a range of fibre volume fractions has been studied theoretically and in monotonic and cyclic deformation (Bauschinger) experiments at room temperature and 77K. The conventional method of analysing Bauschinger experiments is extended to allow for a separation of the mean and thermal stresses. This analysis is applied to experimental results enabling the mean stress hardening rate and the magnitude of the thermal stress to be measured. The experimental results are compared with predictions of the mean field model, which is based on the Eshelby method of determining internal stresses. For that purpose the Eshelby S tensor for a planar random array of fibres is calculated. Because the aluminium/Saffil composites are not isotropic in the transverse directions, the plastic strain used in the calculations has to be determined experimentally. A method for quantifying the anisotropic plastic flow of the aluminium/Saffil composites is proposed and the results are used in calculations of the mean stress hardening rate. A comparison of predictions for the mean stress hardening rate with results of the experimental analysis proposed here shows that good agreement is obtained for low fibre volume fractions at 77 K. The results also show that relaxation of the mean stress increases with fibre volume fraction and that at 77 K the mean stress hardening rate is about a factor of two larger than at room temperature. The measurements of the thermal stresses obtained in the Bauschinger experiments are in quantitative agreement with results obtained in monotonic tests. The magnitude of the thermal stress at room temperature or 77 K is independent of fibre volume fraction and a comparison with predictions shows that relaxation of the thermal stress increases with fibre volume fraction. Cycling in the Bauschinger experiments reduces the thermal stress and hence the separation of the mean and thermal stresses is essential for a reliable measurement of the mean stress hardening rate. Matrix hardening contributes considerably to the overall hardening of the composite, both at room temperature and 77 K. The modified Orowan-Wilson model, which enables the plastic friction coefficient to be measured in copper-tungsten composites, has been applied to the aluminium\Saffil composites. The model requires both the mean stress and the peak stress curves obtained in Bauschinger experiments to be linear in plastic strain. Most of the peak stress curves for the aluminium/Saffil composites are non-linear but for the curves which are linear the predictions of the model are not in quantitative accord with experimental results. This may be because relaxation reduces the mean stress and the source shortening stress in different proportions. The diameter of the Saffil fibres is also close to the lower end of applicability of the model. The temperature dependence of the mean stress hardening rate suggests that relaxation is thermally activated. A model for relaxation of the mean stress is proposed. An equation is derived for the number of Orowan loops per fibre and it is assumed that the rate controlling mechanism of relaxation is cross slip of screw dislocations. The estimated activation energy is independent of fibre volume fraction but the activation volume decreases with increasing fibre volume fraction. The magnitudes of activation energy and activation volume support the assumptions of the model. A preliminary study on the early stages of fatigue shows that persistent slip bands form in the matrix of the aluminium/Saffil composites.
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AVERSA, ALBERTA. "Development and Characterisation of Aluminium Alloys and Aluminium Matrix Composites Produced via Laser Powder Bed Fusion." Doctoral thesis, Politecnico di Torino, 2017. http://hdl.handle.net/11583/2677621.
Full textAbstract:
Nowadays, despite the growing interest about metal additive manufacturing, only a few commercial alloys used for casting are available for these technologies. Therefore, there is the necessity to develop new materials that can exploit the unique opportunities of additive manufacturing processes. The goal of this thesis was to create and characterize new aluminium based materials for powder bed additive manufacturing technologies.
At first, the feasibility of the production of aluminium matrix composites by laser powder bed fusion (LPBF) was investigated. Three different composites were produced in order to study the effect of the reinforcement size and properties on the consolidation. Even if the introduction of a ceramic particles alters the consolidation phenomena of the base alloy, the LPBF process allows the production of dense and crack free aluminium matrix composites. The mechanical characterization of these composites revealed that the mechanical properties, and in particular the yield and ultimate strength, are strongly related to the building parameters used during the LPBF process.
Regarding the study of existing or new alloys, it was observed that the laser scanning and the phenomena that arise in the melt pool allow the obtainment of an almost homogenous composition even when realizing the alloy in situ, i.e. starting from mixed powders of different composition. A specific alloy that takes advantage from the fast cooling that arises during the laser scanning, and that therefore has excellent mechanical properties, was selected in this study.
For both composites and alloys, the laser-powder interaction and the consolidation phenomena were studied and compared by means of single scan tracks analyses which proved to be a promising solution to foresee the behavior of a specific material during the LPBF process.
Finally, the effect of a post processing heat treatment on the microstructure on the mechanical properties of LPBF samples was analysed. In most of the cases, the as-built state can be considered as a supersaturated solid solution and therefore a direct-ageing heat treatment allows the achievement of enhanced mechanical properties. This effect was clearly visible on the A357 alloy and on a modified-7075 alloy, in which 15% and 20% respectively higher hardness values were achieved by the selection of the most suitable ageing heat treatment.
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Shirzadi, Ghoshouni Amir Abbas. "Diffusion bonding aluminium alloys and composites : new approaches and modelling." Thesis, University of Cambridge, 1998. https://www.repository.cam.ac.uk/handle/1810/221876.
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Stanford-Beale, Christopher Andrew. "High temperature deformation of short fibre reinforced aluminium based composites." Thesis, University of Cambridge, 1989. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.315905.
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Ribes, Hervé. "Microstructure de composites aluminium-carbure de silicium après traitements thermomécaniques." Grenoble INPG, 1989. http://www.theses.fr/1989INPG0084.
Full textAbstract:
Ce travail porte sur l'etude de composites a matrices aluminium (al-mg-si) renforcees par des particules de carbure de silicium qui ont ete utilisees soit brut de reception soit prealablement oxydees. Une investigation microstructurale detaillee (realisee en partie par microscopie electronique en transmission) a permis de preciser la nature de l'interface al/sic dans ces composites ainsi que l'evolution de la precipitation apres traitements thermiques. Nous avons montre que l'interface est souvent composee par differentes interphases dont la composition et le mode de formation sont presentes. Nous montrons alors que la nature de l'interface modifie les proprietes mecaniques et en particulier l'allongement a rupture. A partir de l'etude de la precipitation et d'essais de durete, nous montrons qu'il est necessaire d'optimiser les conditions de traitements thermiques dans les composites. Ainsi en modifiant les interfaces, en optimisant la composition de la matrice et les traitements thermiques dans les composites. Ainsi en modifiant les interfaces, en optimisant la composition de la matrice et les traitements thermiques il doit etre possible d'obtenir une nouvelle generation de composites
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Askew, John Russell. "Transient liquid phase bonding of Aluminium-based MMCs." Thesis, Brunel University, 2000. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.324651.
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Negahdari, Zahra. "Reaction sintered alumina-lanthanum hexaaluminate composites." Aachen Shaker, 2009. http://d-nb.info/1000213897/04.
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Whitehouse, Anne Frances. "Damage and failure of discontinuously reinforced aluminium composites during tensile deformation." Thesis, University of Cambridge, 1993. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.319543.
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Lewis, Christopher Alan. "The internal stress state and related microstructural changes during deformation of AlZrOâ†2 metal matrix composites." Thesis, University of Cambridge, 1995. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.338255.
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Bushell, Andrew Charles. "The application of laser-generated ultrasound to the testing of aluminium-epoxy bonded systems." Thesis, University of Warwick, 1993. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.387330.
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Liauw, Christopher Mark. "Influence of surface modification of aluminium hydroxide on the processing and mechanical properties of aluminium hydroxide/polypropylene composites." Thesis, Manchester Metropolitan University, 1994. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.359468.
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Johnson, Peter Kenneth. "The interaction between liquid aluminium and silicone carbide in metal composites." Thesis, Imperial College London, 1990. http://hdl.handle.net/10044/1/46370.
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Al-Azzawi, Ahmad. "Analysis of static and fatigue damage in aluminium/GFRP hybrid composites." Thesis, Cardiff University, 2017. http://orca.cf.ac.uk/106742/.
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This study has focused on investigating the initiation, propagation and effects of damage in fibre-metal laminates (FMLs) specifically Glare® 4B under buckling, postbuckling and high cycle fatigue through the use of novel numerical and experimental techniques. In terms of numerical analysis, a 3D user-defined cohesive zone model (CZM) has been generated to simulate delamination initiation and growth in specimens under static compressive stresses, using the software Abaqus. The generated models have been validated using a comprehensive literature review in order to gather reliable mechanical properties for the Glare® material constituents. Following this, a modified cohesive zone model (CZM) based on a trapezoidal traction-separation law has been developed by the author to simulate damage evolution under high cycle fatigue loading. This model was implemented through a user-written VUMAT subroutine working through the interface of Abaqus/Explicit software. This model is able to simulate elastic-plastic interfacial damage behaviour and as such is suitable for ductile adhesives including toughened epoxy unlike bilinear cohesive zone models which can only accurately simulate damage in brittle adhesives. This makes it suitable for modelling any material interface which incorporates ductile adhesives. The numerical buckling results were validated using a series of experimental tests conducted on Glare® 4B specimens containing splice and doubler features in addition to flat specimens containing artificial circular delamination manufactured by Airbus Germany, demonstrating the ability of the models developed to predict the onset and propagation of damage. Experimental fatigue tests were then implemented on Glare® 4B specimens containing splice and doubler features manufactured in-house, to Abstract iii obtain fatigue life for these types of joints, with fatigue parameters extracted from literature on similar grades of Glare® used to validate the trapezoidal traction-separation law based cohesive zone model. Static tests were monitored using Digital Image Correlation (DIC) to provide full-field displacement data and Acoustic Emission (AE) for the detection and location of the damage using traditional AE analysis and novel Delta-T techniques respectively, with Acoustic Emission (AE) using traditional AE analysis technique being used for damage detection under fatigue loading. Finite element models were also generated to model the buckling and postbuckling behaviour of Glare specimens containing splice and doubler joints and showed good agreement with experiments in terms of in-plane and out-of-plane displacements. In experiments, artificial delaminations representative of those which could potentially be generated during manufacturing had a negligible effect on the compressive strength of specimens. Acoustic Emission (AE) was successfully used to detect and locate damage initiation and propagation under buckling loads. Of particular importance in this body of work are the implementation of a trapezoidal traction separation model to predict the initiation and propagation of damage in elastic-plastic materials such as the resin used in the Fibre Metal Laminate Glare under high cycle fatigue and the detection and location of this damage using a bespoke mapping algorithm for the interpretation of Acoustic Emission data.
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Liu, Ziqian. "Life cycle assessment of composites and aluminium use in aircraft systems." Thesis, Cranfield University, 2013. http://dspace.lib.cranfield.ac.uk/handle/1826/8573.
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As a consequence of the gradually expanding aviation network, civil aircrafts
are occupying an increasingly high proportion of the transport industry. Air
transport now dominates the intercity rapid transit, long-distance passenger
transport, international passenger and freight transport, and specific regional
transport, advantaged as it is by fast, convenient, comfortable and safe options.
Nevertheless, the potential adverse impact on the environment of air transport,
specifically, in the case of this research, the pollutants generated during aircraft
production remain a concern.
Using the A319 as the main research object, this thesis will conduct a life cycle
assessment research about its environmental impact. Moreover, it will focus on
the impact brought by the application of composite materials to the entire life
cycle environmental influence of the aircraft, particularly the material production
and disposal process. At the same time, a contrast with the B737-800 aircraft
will be made due to their different composite material use rate.
Firstly, the inventory list is formed by collecting data about the weight and
material of every component in the aircraft, the input and output information of
the composite material manufacturing process, the disposal situation of the
aircraft and the treatment of composite material. Secondly, the impact
assessment of the aircraft is conducted to examine their environmental
influence. During the assessment, each life stage and the whole life cycle of the
aircrafts is assessed, and a comparison between these two aircraft types is
made. Finally, according to the impact assessment result, the environment load
increase brought by the manufacturing of composite material and the decrease
of the environment impact due to the weight reduction character of composite
material is calculated and compared.
From this research, the conclusion that the use of composite material has a
positive effect on decreasing the environmental impact of the whole life cycle of
the aircraft is obtained. This will enable aircraft manufacturers to target these
reas for improvement, to produce more comfortable, environment friendly and
market competitive aircraft.
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Hanus, Eric. "Galetage des composites à matrice métallique." Palaiseau, Ecole polytechnique, 1995. http://www.theses.fr/1995EPXX0008.
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Les composites à matrice métallique renforces par des particules céramiques, pour lesquels la matrice et le renfort supportent la charge appliquée, sont de nos jours d'un intérêt industriel indéniable. Ils offrent comme avantages des propriétés relativement isotropes, un faible cout, une grande maniabilité et des performances significativement meilleures que celles des alliages non renforces constituant leur matrice. Mais avant de procéder à leur exploitation commerciale certaines caractéristiques restent a déterminer, notamment leur comportement en fatigue est un point crucial en vue d'application comme matériau de structure. Ainsi le but de ce travail est l'étude de l'influence du traitement mécanique de surface de galetage sur ces composites. Lorsqu'une phase céramique est finement dispersée dans une matrice métallique des contraintes résiduelles sont invariablement générées. Le premier objectif a été de mesurer dans les deux phases par diffraction aux rayons x l'évolution de ces contraintes après traitement thermique, galetage et fatigue. Dans le cas d'un alliage d'aluminium 2014 renforce par 15 pour-cent en volume de particules de carbure de silicium il a été trouvé que d'importantes pseudomacrocontraintes sont présentes après traitement thermique, que de fortes macrocontraintes de compression sont générées par galetage, et que le taux de relaxation de ces macrocontraintes dépend du signe du chargement de fatigue. Des résultats nouveaux concernant la répartition en surface et en profondeur des macro- et des pseudomacro-contraintes ont été obtenus après galetage et fatigue. Un parallèle avec la largeur du pic de diffraction et la dureté du matériau a été établi. Par ailleurs les courbes de Wohler du composite traite au maximum de dureté et ou non galeté indiquent un gain de 30 pour-cent en limite de fatigue attribuable au galetage. Une deuxième partie traite la modélisation du galetage qui a été décomposée en trois temps: détermination de la distribution de pression au niveau du contact conforme entre le galet et l'éprouvette, calcul des champs mécaniques a l'état stabilise par une méthode stationnaire directe et analyse de la répartition des contraintes résiduelles a l'échelle microscopique via un modèle d'éléments finis a hypothèses périodiques. Une étude paramétrique des champs résiduels macroscopiques a mis en valeur le rôle prépondérant joue par la loi de comportement et le coefficient de frottement. Les données numériques ont ensuite été comparées aux données expérimentales déterminées précedemment, montrant un bon accord en termes de couche affectée et de profil de macrocontraintes résiduelles
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Bauer, Bernhard. "Aluminium-modified polymeric precursors to Si³N⁴?SiC ceramics." Thesis, University of Oxford, 2008. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.670051.
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