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Abdullah, Abu. "Machining of aluminium based Metal Matrix Composite (MMC)." Thesis, University of Warwick, 1996. http://wrap.warwick.ac.uk/34661/.
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The machining of aluminium 2618 particulate reinforced Metal Matrix Composite (MMC) with 18 vol. % silicon carbide (SiC) using cemented carbide cutting tools has been undertaken. Two grades of cemented carbide inserts, uncoated K68 grade and coated KC910 grade (coated with TiC and A1203) having negative and positive rake angles (with and without chip breaker) have been used to machine this material in order to understand the machining process, tool failure modes and wear mechanisms. Turning tests in the speed range 15 - 10 m/min have been carried out at 0.2,0.4 and 0.6 mm/rev feed rates and 2 mm and 4 mm depths of cut. Both cemented carbide tools have been shown to be capable of machining the MMC and give reasonable tool lives. Low speed and high feed rate are found to be a good combination in order to machine this material effectively. Coated KC910 grade inserts with negative rake angle gave the best performance. The use of a chip breaker has no significant effect on the machining process of the NMC because the material is one which inherently short chips due to ductility limitations caused by the particles. Tool failure mode studies showed that the tools failed by flank wear. Tool wear mechanism analysis indicated that abrasion wear was the tool life controlling factor under all cutting conditions. The tool wear is related to the direct contact between the abrasive hard SiC particles and the cutting edge and their relative motion to the rake and clearance face. Hence, the hardness of the SiC particles is a dominant factor for the tool wear. Two separatem odels of abrasio. n haye.b een suggested.B uilt-up edge (BUE) which has a distinct shape was more pro i1ounced at lower cutting speeds, high feed rates and greater depth of cut. The presence of BUE has been found to increase tool life and reduce tool wear but at the expense of surface finish. The increase in tool life or reduction in tool wear is likely due to the protective layer that the BUE formed on the tool surface preventing a direct contact between the tool and chip. Linear regression analysis showed that the value of Taylor exponent n is high (0.8-1.0) compared to the values of n (0.2-0.3) obtained when machining steel. This indicates that the tool life is less sensitive to cutting speed for MMC than it is for steel.
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Daymond, Mark Richard. "Evolution of internal stresses in a whisker reinforced MMC undergoing thermal cycling." Thesis, University of Cambridge, 1996. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.266242.
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Coelho, Reginaldo Teixeira. "The machinability of aluminium-based SiC reinforced metal matrix composite (MMC) alloy with emphasis on hole production." Thesis, University of Birmingham, 1995. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.340966.
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Li, Maojun. "Drilling of carbon fibre reinforced plastic (CFRP) and metal matrix composites (MMC)." Thesis, University of Birmingham, 2015. http://etheses.bham.ac.uk//id/eprint/5953/.
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The use of carbon fibre reinforced plastic (CFRP) and metal matrix composites (MMC) is steadily increasing as an alternative to traditional metallic materials in various industrial sectors. The overall aim of the project is to assess the machinability when drilling epoxy based CFRP and Al/SiCp MMC composites and understand its effects on feature quality and workpiece integrity. Specific objectives of the project relate to establishing preferred/optimum operating parameters (cutting speed, feed rate and drill strategies) and investigating the influence of cutting environment (dry, chilled air, high pressure internal/external supplied coolant and low pressure flood) for drilling specific composite material systems. Key response measures include tool wear/life, thrust force/torque, hole size and geometrical accuracy, hole edge quality (delamination, uncut fibres and burrs) as well as workpiece surface integrity (surface roughness, microhardness, fibre/particle pullout, subsurface damage, etc.). The latest cutting tool materials and advanced diamond coatings, drill geometry and design format (e.g. domed PCD) were assessed in an attempt to improve productivity levels, tool life and hole quality. Tool wear mechanisms and its effect on hole surface quality were also investigated.
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Kenningley, Scott David Peter. "High temperature thermal and mechanical load characterisation of a steel fibre reinforced aluminium metal matrix composite (AlMMC) for automotive diesel pistons." Thesis, University of Manchester, 2014. https://www.research.manchester.ac.uk/portal/en/theses/high-temperature-thermal-and-mechanical-load-characterisation-of-a-steel-fibre-reinforced-aluminium-metal-matrix-composite-almmc-for-automotive-diesel-pistons(5cc789fc-d64e-4905-bc1c-beb0e3b9c0df).html.
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In modern automotive engines, the vast majority of light vehicle diesel (LVD) pistons are made from gravity die cast monolithic AlSi based alloy systems. Presently, the market drivers for reduced emissions, more efficient fuel consumption and increased specific power output are providing cyclic thermal and mechanical fatigue loading above the safe life durability threshold for the current AlSi based alloy systems. Peak temperatures in the diesel piston’s fatigue critical combustion bowl region are presently 420 °C for the AlSi based alloys, which represents a homologous TH value in excess of 0.8. In combination with peak temperatures of 420 C, the pistons are subject to cylinder pressures up to 220 bar, inducing mechanical stress amplitudes 15-20% greater than the allowable component fatigue strength for 1x108 cycles, in some applications. This durability deficit naturally leads to a requirement for new material and process solutions aimed at improving thermal and mechanical fatigue resistance at temperatures in excess of 420 C.One solution to this problem is to locally reinforce the pistons combustion bowl edge with a metal matrix composite (MMC) system. In this study, an aluminium based metal matrix composite (AlMMC) has been investigated and has shown some promise with increases in iso-thermal high cycle (1x 107) fatigue strength of 50 % compared to standard monolithic piston alloys. The AlMMC consists of a premium AlSi based LVD piston alloy matrix reinforced with 0.15 Vf of an interconnected network of 2-4 mm long Fe based fibres. The AlMMC is manufactured by pressure assisted infiltration of a sintered metallic fibre preform with as cast materials having a pore density of 0.2 %. In contrast to the use of ceramic fibre reinforcement systems generally requiring high pressure infiltration techniques, preform infiltration is considered possible with a comparably inexpensive manufacturing route. The Fe based fibre preforms can be infiltrated at lower pressure due to the reactivity between the Fe based fibres and the AlSi based matrix alloy. Unfortunately, this increased reactivity, although an advantage for preform infiltration, can result in (FeAlXX)Si(+X) interfacial reaction products forming between the fibre and matrix at operating temperatures of greater than 440 °C. These interfacial reactions result in a 15-20 m interfacial intermetallic layer after prolonged periods of exposure (>500 hrs), resulting in depleted fibre Vf and void formations on the matrix side of the interface.
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Xia, Ji. "TENSION AND FATIGUE BEHAVIOR OF AL-2124/SIC-PARTICULATE METAL-MATRIX COMPOSITES." Case Western Reserve University School of Graduate Studies / OhioLINK, 2019. http://rave.ohiolink.edu/etdc/view?acc_num=case1548169132710822.
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Pallikonda, Mahesh Kumar Pallikonda. "FORMING A METAL MATRIX NANOCOMPOSITE (MMNC) WITH FULLY DISPERSED AND DEAGGLOMERATED MULTIWALLED CARBON NANOTUBES (MWCNTs)." Cleveland State University / OhioLINK, 2017. http://rave.ohiolink.edu/etdc/view?acc_num=csu1503937490966191.
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Tu, Zhiqiang. "Fabrication and Mechanical Properties of Carbon Fiber Reinforced Aluminum Matrix Composites by Squeeze Casting." Thesis, Université d'Ottawa / University of Ottawa, 2020. http://hdl.handle.net/10393/40523.
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Rapid modern technological changes and improvements bring great motivations in advanced material designs and fabrications. In this context, metal matrix composites, as an emerging material category, have undergone great developments over the past 50 years. Their primary applications, such as automotive, aerospace and military industries, require materials with increasingly strict specifications, especially high stiffness, lightweight and superior strength. For these advanced applications, carbon fiber reinforced aluminum matrix composites have proven their enormous potential where outstanding machinability, engineering reliability and economy efficiency are vital priorities.
To contribute in the understanding and development of carbon fiber reinforced aluminum matrix composites, this study focuses on composite fabrication, mechanical testing and physical property modelling. The composites are fabricated by squeeze casting. Plain weave carbon fiber (AS4 Hexcel) is used as reinforcement, while aluminum alloy 6061 is used as matrix. The improvement of the squeeze casting fabrication process is focused on reducing leakage while combining thermal expansion pressure with post-processing pressing. Three different fiber volume fractions are investigated to achieve optimum mechanical properties. Piston-on-ring (POR) bend tests are used to measure the biaxial flexural stiffness and fracture strength on disc samples. The stress-strain curves and fracture surfaces reveal the effect of fiber-matrix interface bonding on composite bend behaviour. The composites achieved up to 11.6%, 248.3% and 90.1% increase in flexural modulus, strain hardening modulus and yield strength as compared with the unreinforced aluminum alloy control group, respectively. Analytical modelling and finite element modelling are used to comparatively characterise and verify the composite effective flexural modulus and strength. Specifically, they allowed
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evaluating how far the experimental results deviate from idealized assumptions of the models, which provides an insight into the composite sample quality, particularly at fiber-matrix interfaces. Overall, the models agree well with experimental results in identifying an improvement in flexural modulus up to a carbon fiber volume fraction of 4.81vol%. However, beyond a fiber content of 3.74vol%, there is risk of deterioration of mechanical properties, particularly the strength. This is because higher carbon fiber volume fractions restrict the infiltration and wetting of carbon fibre by the liquid, potentially leading to poor fiber-matrix interface bonding. It is shown that higher thermal expansion pressures and subsequent post-processing pressing can overcome this challenge at higher carbon fiber volume contents by reducing fiber-aluminum contact angle, improving infiltration, reducing defects such as porosity, and overall improving fiber-matrix bonding.
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Vargas, Alexandro. "Machinability Study on Silicon Carbide Particle-Reinforced Aluminum Alloy Composite with CVD Diamond Coated Tools." Scholarly Commons, 2017. https://scholarlycommons.pacific.edu/uop_etds/215.
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Particle-reinforced MMCs (pMMC) such as aluminum alloys reinforced with ceramic silicon carbide particles (AlSiC) require special cutting tools due to the high hardness and abrasive properties of the ceramic particles. Diamond coated cutting tools are ideal for machining this type of pMMC. Previous research studies focus on the machinability of pMMCs with low ceramic content. The aim of this research is to determine the optimal cutting parameters for machining AlSiC material containing high silicon carbide particle reinforcement (>25%). The optimal cutting parameters are determined by investigating the relationship between cutting forces, tool wear, burr formation, surface roughness, and material removal rate (MRR). Experimental milling tests are conducted using CVD diamond coated end mills and non-diamond tungsten carbide end mills. It was found that low tool rotation speeds, feed rates and depths of cut are necessary to achieve smoother surface finishes of R a < 1 μm. A high MRR to low tool wear and surface roughness ratio was obtainable at a tool rotation speed of 6500 r/min, feed rate of 762 mm/min and depth of cut of 3 mm. Results showed that a smooth surface roughness of the workpiece material was achieved with non-diamond tungsten carbide end mills, however, this was at the expense of extreme tool wear and high burr formation. The use of coolant caused a 50% increase in tool wear compared to the dry-cutting experiments which had lower cutting tool forces.
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Stjernstoft, Tero. "Machining of Some Difficult-to-Cut Materials with Rotary Cutting Tools." Doctoral thesis, KTH, Production Engineering, 2004. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-3693.
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<p>Automobile and aero industries have an increasing interestin materials with improved mechanical properties. However, manyof these new materials are classified as difficult-to-cut withconventional tools. It is obvious that tools, cutting processesand cutting models has to be devel-oped parallel to materialsscience. In this thesis rotary cutting tools are tested as analternative toexpensive diamond or cubic bore nitridetools.</p><p>Metal matrix composites mostly consist of a light metalalloy (such as aluminium or titanium) reinforced with hard andabrasive ceramic parti-cles or fibres. On machining, thereinforcement results in a high rate of tool wear. This is themain problem for the machining of MMCs. Many factors affect thelife length of a tool, i.e. matrix alloy, type, size andfraction of the reinforcement, heat treatment, cuttingconditions and tool properties.</p><p>In tests, the Al-SiC MMC formed a deformation layer duringmilling, probably affected by lack of cooling. The dominatingfactor for tool life was the cutting speed. Water jet or CO2cooling of turning did not provide dramatic increase in toollife. With PCD, cutting speeds up to 2000 m/min were usedwithout machining problems and BUE formation. Tool flank wearwas abrasive and crater wear created an "orange-peel type" wearsurface. PCD inserts did not show the typical increase in flankwear rate at the end of its lifetime.</p><p>The use of self-propelled rotary tools seems to be apromising way to increase tool life. No BUE was formed on therotary tool at high cutting data. The measurements indicatethat the rotary tool creates twice as good surface as PCDtools. The longest tool life was gained with an inclinationangle of 10 degrees. Tool costs per component will beapproximately the same, but rotary cutting tool allows higherfeeds and therefore a higher production rate and thus a lowerproduction cost.</p><p>The rotary cutting operation might have a potential toincrease productiv-ity in bar peeling. The lack of BUE withrotary cutting gives hope on higher tool life. The test resultsshow that tool wear was 27% lower with rotary cutting tools.Increase of cutting speed from 22 to 44 m/min did not affectcutting forces. This indicates that the cutting speed canincrease without significant change in tool wear rate.</p><p>Issues related to rotary cutting like cutting models,cutting processes, standards, tools and models have beendiscussed. A tool wear model with kinetic energy has beendiscussed.</p><p><b>KEYWORDS:</b>Difficult-to-Cut material, Metal MatrixComposite (MMC), Machining, Machinability, Rotary Cutting Tool,Acoustic Emission</p>
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Nestler, Daisy Julia. "Beitrag zum Thema VERBUNDWERKSTOFFE - WERKSTOFFVERBUNDE." Doctoral thesis, Universitätsbibliothek Chemnitz, 2014. http://nbn-resolving.de/urn:nbn:de:bsz:ch1-qucosa-134459.
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Vielschichtige Eigenschaftsprofile benötigen zunehmend moderne Verbundwerkstoffe und Werkstoffverbunde einschließlich der raschen Entfaltung neuer Fertigungstechnologien, da der monolithische Werkstoff bzw. ein einziger Werkstoff den heutigen komplexen Anforderungen nicht mehr genügen kann. Zukünftige Werkstoffsysteme haben wirtschaftlich eine Schlüsselposition und sind auf den Wachstumsmärkten von grundlegender Bedeutung. Gefragt sind maßgeschneiderte Leichtbauwerkstoffe (tailor-made composites) mit einem adaptierten Design. Dazu müssen Konzepte entwickelt werden, um die Kombination der Komponenten optimal zu gestalten. Das erfordert werkstoffspezifisches Wissen und Korrelationsvermögen sowie die Gestaltung komplexer Technologien, auch unter dem Aspekt der kontinuierlichen Massen- und Großserienfertigung (in-line, in-situ) und damit der Kostenreduzierung bislang teurer Verbundwerkstoffe und Werkstoffverbunde. In der vorliegenden Arbeit wird in vergleichbarer und vergleichender Art und Weise sowie abstrahierter Form ein Bogen über das Gesamtgebiet der Verbundwerkstoffe und Werkstoffverbunde gespannt. Eine zusammenfassende Publikation über dieses noch sehr junge, aber bereits breit aufgestellte Wissenschaftsgebiet fehlt bislang. Das ist der Separierung der einzelnen, fest aufgeteilten Gruppierungen der Verbundwerkstoffe geschuldet. Querverbindungen werden selten hergestellt. Dieses Defizit in einem gewissen Maße auszugleichen, ist Ziel der Arbeit. Besondere Berücksichtigung finden Begriffsbestimmungen und Klassifikationen, Herstellungsverfahren und Eigenschaften der Werkstoffe. Es werden klare Strukturierungen und Übersichten herausgearbeitet. Zuordnungen von etablierten und neuen Technologien sollen zur Begriffsstabilität der Terminologien „Mischbauweise“ und „Hybrider Verbund“ beitragen. Zudem wird die Problematik „Recycling und Recyclingtechnologien“ diskutiert. Zusammenfassend werden Handlungsfelder zukünftiger Forschungs- und Entwicklungsprojekte spezifiziert. Aus dem Blickwinkel der verschiedenen Herstellungsrouten insbesondere für Halbzeuge und Bauteile und der dabei gewonnenen Erkenntnisse werden verallgemeinerte Konzepte für tailor-made Verbundwerkstoffe und Werkstoffverbunde vorgeschlagen („Stellschraubenschema“). Diese allgemeinen Werkstoffkonzepte werden auf eigene aktuelle Forschungsprojekte der Schwerpunktthemen Metallmatrix- und Polymermatrix-Verbundwerkstoffe sowie der hybriden Werkstoffverbunde appliziert. Forschungsfelder für zukünftige Projekte werden abgeleitet. Besonderes Augenmerk gilt den hybriden Verbunden als tragende Säule zukünftiger Entwicklungen im Leichtbau. Hier spielen in-line- und in-situ-Prozesse eine entscheidende Rolle für eine großseriennahe, kosteneffiziente und ressourcenschonende Produktion<br>Complex property profiles require increasingly advanced composite materials and material compounds, including the rapid deployment of new production technologies, because the monolithic material or a single material can no longer satisfy today's complex requirements. Future material systems are fundamentally important to growth markets, in which they have an economically key position. Tailor-made lightweight materials (tailor-made composites) with an adapted design are needed. These concepts have to be developed to design the optimum combination of components. This requires material-specific knowledge and the ability to make correlations, as well as the design of complex technologies. Continuous large-scale and mass production (in-line, in-situ), thus reducing the costs of previously expensive composite materials and material compounds, is also necessary. The present work spans the entire field of composite materials and material compounds in a comparable and comparative manner and abstract form. A summarizing publication on this still very new, but already broad-based scientific field is not yet available. The separation of the individual, firmly divided groups of the composite materials is the reason for this. Cross-connections are rarely made. The objective of this work is to compensate to some extent for this deficiency. Special consideration is given to definitions and classifications, manufacturing processes and the properties of the materials. Clear structures and overviews are presented. Mapping established and new technologies will contribute to the stability of the terms "mixed material compounds" and "hybrid material compounds". In addition, the problem of recycling and recycling technologies is discussed. In summary, areas for future research and development projects will be specified. Generalized concepts for tailor-made composite materials and material compounds are proposed ("adjusting screw scheme") with an eye toward various production routes, especially for semi-finished products and components, and the associated findings. These general material concepts are applied to own current research projects pertaining to metal-matrix and polymer-matrix composites and hybrid material compounds. Research fields for future projects are extrapolated. Particular attention is paid to hybrid material compounds as the mainstay of future developments in lightweight construction. In-line and in-situ processes play a key role for large-scale, cost- and resource-efficient production
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Nestler, Daisy Julia. "Beitrag zum Thema VERBUNDWERKSTOFFE - WERKSTOFFVERBUNDE: Status quo und Forschungsansätze." Doctoral thesis, Universitätsverlag Chemnitz, 2012. https://monarch.qucosa.de/id/qucosa%3A20009.
Full textAbstract:
Vielschichtige Eigenschaftsprofile benötigen zunehmend moderne Verbundwerkstoffe und Werkstoffverbunde einschließlich der raschen Entfaltung neuer Fertigungstechnologien, da der monolithische Werkstoff bzw. ein einziger Werkstoff den heutigen komplexen Anforderungen nicht mehr genügen kann. Zukünftige Werkstoffsysteme haben wirtschaftlich eine Schlüsselposition und sind auf den Wachstumsmärkten von grundlegender Bedeutung. Gefragt sind maßgeschneiderte Leichtbauwerkstoffe (tailor-made composites) mit einem adaptierten Design. Dazu müssen Konzepte entwickelt werden, um die Kombination der Komponenten optimal zu gestalten. Das erfordert werkstoffspezifisches Wissen und Korrelationsvermögen sowie die Gestaltung komplexer Technologien, auch unter dem Aspekt der kontinuierlichen Massen- und Großserienfertigung (in-line, in-situ) und damit der Kostenreduzierung bislang teurer Verbundwerkstoffe und Werkstoffverbunde.
In der vorliegenden Arbeit wird in vergleichbarer und vergleichender Art und Weise sowie abstrahierter Form ein Bogen über das Gesamtgebiet der Verbundwerkstoffe und Werkstoffverbunde gespannt. Eine zusammenfassende Publikation über dieses noch sehr junge, aber bereits breit aufgestellte Wissenschaftsgebiet fehlt bislang. Das ist der Separierung der einzelnen, fest aufgeteilten Gruppierungen der Verbundwerkstoffe geschuldet. Querverbindungen werden selten hergestellt. Dieses Defizit in einem gewissen Maße auszugleichen, ist Ziel der Arbeit. Besondere Berücksichtigung finden Begriffsbestimmungen und Klassifikationen, Herstellungsverfahren und Eigenschaften der Werkstoffe. Es werden klare Strukturierungen und Übersichten herausgearbeitet. Zuordnungen von etablierten und neuen Technologien sollen zur Begriffsstabilität der Terminologien „Mischbauweise“ und „Hybrider Verbund“ beitragen. Zudem wird die Problematik „Recycling und Recyclingtechnologien“ diskutiert. Zusammenfassend werden Handlungsfelder zukünftiger Forschungs- und Entwicklungsprojekte spezifiziert. Aus dem Blickwinkel der verschiedenen Herstellungsrouten insbesondere für Halbzeuge und Bauteile und der dabei gewonnenen Erkenntnisse werden verallgemeinerte Konzepte für tailor-made Verbundwerkstoffe und Werkstoffverbunde vorgeschlagen („Stellschraubenschema“). Diese allgemeinen Werkstoffkonzepte werden auf eigene aktuelle Forschungsprojekte der Schwerpunktthemen Metallmatrix- und Polymermatrix-Verbundwerkstoffe sowie der hybriden Werkstoffverbunde appliziert. Forschungsfelder für zukünftige Projekte werden abgeleitet. Besonderes Augenmerk gilt den hybriden Verbunden als tragende Säule zukünftiger Entwicklungen im Leichtbau. Hier spielen in-line- und in-situ-Prozesse eine entscheidende Rolle für eine großseriennahe, kosteneffiziente und ressourcenschonende Produktion.<br>Complex property profiles require increasingly advanced composite materials and material compounds, including the rapid deployment of new production technologies, because the monolithic material or a single material can no longer satisfy today's complex requirements. Future material systems are fundamentally important to growth markets, in which they have an economically key position. Tailor-made lightweight materials (tailor-made composites) with an adapted design are needed. These concepts have to be developed to design the optimum combination of components. This requires material-specific knowledge and the ability to make correlations, as well as the design of complex technologies. Continuous large-scale and mass production (in-line, in-situ), thus reducing the costs of previously expensive composite materials and material compounds, is also necessary.
The present work spans the entire field of composite materials and material compounds in a comparable and comparative manner and abstract form. A summarizing publication on this still very new, but already broad-based scientific field is not yet available. The separation of the individual, firmly divided groups of the composite materials is the reason for this. Cross-connections are rarely made.
The objective of this work is to compensate to some extent for this deficiency. Special consideration is given to definitions and classifications, manufacturing processes and the properties of the materials. Clear structures and overviews are presented. Mapping established and new technologies will contribute to the stability of the terms "mixed material compounds" and "hybrid material compounds". In addition, the problem of recycling and recycling technologies is discussed. In summary, areas for future research and development projects will be specified. Generalized concepts for tailor-made composite materials and material compounds are proposed ("adjusting screw scheme") with an eye toward various production routes, especially for semi-finished products and components, and the associated findings. These general material concepts are applied to own current research projects pertaining to metal-matrix and polymer-matrix composites and hybrid material compounds. Research fields for future projects are extrapolated. Particular attention is paid to hybrid material compounds as the mainstay of future developments in lightweight construction. In-line and in-situ processes play a key role for large-scale, cost- and resource-efficient production.
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Bindas, Erica Bindas. "EFFECT OF TEMPERATURE, STRAIN RATE, AND AXIAL STRAIN ON DIRECT POWDER FORGED ALUMINUM-SILICON CARBIDE METAL MATRIX COMPOSITES." Case Western Reserve University School of Graduate Studies / OhioLINK, 2018. http://rave.ohiolink.edu/etdc/view?acc_num=case1530871866585058.
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Pritchard, Joshua D. "Design, Fabrication, and Analysis of a Multi-Layer, Low-Density, Thermally-Invariant Smart Composite via Ultrasonic Additive Manufacturing." The Ohio State University, 2014. http://rave.ohiolink.edu/etdc/view?acc_num=osu1406284899.
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KRISHNAN, MANICKAVASAGAM. "Investigation of material and mechanical properties of Al alloy and Al based MMC parts produced by DMLS for industrial application." Doctoral thesis, Politecnico di Torino, 2014. http://hdl.handle.net/11583/2530290.
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Additive Manufacturing (AM) is the process of joining materials layer upon layer to produce parts from CAD model. Direct Metal Laser Sintering (DMLS) is an AM process in which metallic parts can be produced. The knowledge of material and mechanical properties are important for producing lightweight and functional parts. Hence, this thesis focuses on characterizing material and mechanical properties of a lightweight alloy processed by DMLS, and using it as metal matrix for producing composites in DMLS process.
AlSi10Mg was selected as lightweight alloy and it is similar to an A360 cast alloy in chemical composition. The morphology and size distribution of the AlSi10Mg starting powder was investigated by using Field Emission Scanning Electron Microscope (FESEM) and laser granulometry, respectively. Chemical composition of the AlSi10Mg powder was analyzed by using Inductive Coupled Plasma test. Material characterization of AlSi10Mg specimen produced by DMLS was carried out by using optical microscope, FESEM and X-ray Diffraction technique (XRD). Thereafter, mechanical properties such as hardness, tensile strength and Charpy impact energy were evaluated. Effect of different post processing operations on mechanical properties of AlSi10Mg parts were also investigated. Due to the very fine microstructure of the AlSi10Mg parts produced by DMLS process, nanoindentation measurements were performed. Investigation of process parameters and their effect on final density and hardness of AlSi10Mg specimens based on Design of Experiments (DOE) approach was carried out. Regression analysis was also conducted. Effect of the heat treatment (e.g. precipitation hardening T6) on the AlSi10Mg parts was also investigated.
Composite materials offer better properties comparing to traditional materials. The Metal Matrix Composite was produced by DMLS process. The matrix was of AlSi10Mg and 10 wt% SiC was used as ceramic reinforcement. The microstructure of the composite was studied by using optical microscopy and FESEM. Evaluation of mechanical properties of the composite specimens was carried out.
Finally, the production of a complex shape lightweight structure by DMLS was studied.
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Hofmeister, Clara. "Development of Nitrogen Concentration During Cryomilling of Aluminum Composites." Master's thesis, University of Central Florida, 2013. http://digital.library.ucf.edu/cdm/ref/collection/ETD/id/5791.
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The ideal properties of a structural material are light weight with extensive strength and ductility. A composite with high strength and tailorable ductility was developed consisting of nanocrystalline AA5083, boron carbide and coarser grained AA5083. The microstructure was determined through optical microscopy and transmission electron microscopy. A technique was developed to determine the nitrogen concentration of an AA5083 composite from secondary ion mass spectrometry utilizing a nitrogen ion-implanted standard. Aluminum nitride and amorphous nitrogen-rich dispersoids were found in the nanocrystalline aluminum grain boundaries. Nitrogen concentration increased as a function of cryomilling time up to 72hours. A greater nitrogen concentration resulted in an enhanced thermal stability of the nanocrystalline aluminum phase and a resultant increase in hardness. The distribution of the nitrogen-rich dispersoids may be estimated considering their size and the concentration of nitrogen in the composite. Contributions to strength and ductility from the Orowan relation can be more accurately modeled with the quantified nitrogen concentration.<br>M.S.M.S.E.<br>Masters<br>Materials Science Engineering<br>Engineering and Computer Science<br>Materials Science and Engineering; Accelerated BS to MS
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Pratas, Sérgio Rodrigo Marques. "Implementação de ferramentas de diamante CVD no fabrico de metal duro." Master's thesis, Universidade de Aveiro, 2015. http://hdl.handle.net/10773/17182.
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Mestrado em Ciência e Engenharia de Materiais<br>Este projeto realizado na UA e na Durit, teve como objetivo alterar um reator HFCVD de dimensão piloto para a produção de revestimentos em multicamada de diamante micro e nanocristalino sobre brocas e fresas de metal duro. As modificações incluíram a utilização de filamentos de W de diâmetro 0,125 mm, a alteração do porta-substratos de cobre por um de cerâmico de nitreto de silício, o isolamento do termopar e a fixação de distâncias entre os tubos que direcionam os gases percursores para as ferramentas e os filamentos e entre os filamentos inferiores e o porta-substratos.
Com base nestas alterações desenvolveram-se as seguintes condições para o crescimento de filmes de diamante microcristalino (MCD) e nanocristalino (NCD), válidas para filmes simples ou em multicamada e para o revestimento de uma ou várias ferramentas:
- MCD: fluxo total de 1465 ml/min, com 98,5% de H2 e 1,5% de CH4, temperatura dos filamentos de 2200 ºC e do substrato entre 820-850 ºC;
- NCD: fluxo total de 400 ml/min, com 87,6 % de H2, 3,6 % de CH4 e 8,8 % de árgon, temperatura dos filamentos superior a 2175 ºC e do substrato de 700 °C.
Em ambas as condições conseguiu-se utilizar o mesmo valor de pressão (15 mbar) o que facilita a transição dos parâmetros nos revestimentos em multicamada. Obtiveram-se taxas de crescimento de 1 μm/h para MCD e 0,4 μm/h para NCD.
De um lote de ferramentas depositadas em simultâneo usou-se uma broca de 3,6 mm de diâmetro na furação de um compósito MMC (Al-15%Al2O3). As forças axiais de corte (Fz) e as forças tangenciais (Fx e Fy) medidas através de um dinamómetro tri-axial foram comparadas com as forças de corte sentidas por uma ferramenta não revestida com diâmetro idêntico e com os mesmos parâmetros de furação: avanço, f= 0,025 – 0,149 mm/rotação; velocidade de corte, Vc= 25 – 65 m/min e velocidade de penetramento, Vf= 110-660 mm/min.
Inicialmente a ferramenta não revestida apresenta esforços de corte menores, mas em condições mais agressivas fratura catastroficamente por gripagem no furo, devido provavelmente a desgaste excessivo da aresta de corte. A ferramenta revestida em multicamada sofre fratura apenas na aresta de corte, muito provavelmente devido ao pré tratamento que remove o cobalto. No entanto e apesar da fratura, o filme de diamante continuou a participar no processo de corte, tanto na face de ataque como na face de saída, o que impede a falha catastrófica da ferramenta, ao contrário do que acontece com a não revestida.<br>This project was carried out at UA and Durit, and aimed at modifying a HFCVD pilot scale reactor for the production of multilayer coatings of micro and nanocrystalline diamond on carbide drill bits and cutters. The modifications made include the use of 0.125 mm diameter W of filaments, the change copper carrier substrates by a silicon nitride ceramic, isolating the thermocouple, setting the distance between the filaments and the tubes that direct the precursor gases to the tools and fixing the distance between the bottom filaments and the substrate holder.
Based on these changes the following conditions were developed for the growth of microcrystalline (MCD) and nanocrystalline (NCD) diamond films valid for single and multilayer films and for coating one or several tools:
- MCD: total flow of 1465 ml/min with 98.5% H2 and 1.5% CH4, filament temperature of 2,200 °C and substrate temperature between 820-850 °C;
- NCD: total flow of 400 ml/min with 87.6% H2, 3.6% CH4 and 8.8% argon, filament temperature higher than 2175 ° C and substrate temperature of 700 °C.
In both conditions it was possible to use the same pressure (15 mbar) which facilitates the transition between the MCD and NCD parameters when depositing multilayer coatings. Growth rates of 1 μm/hr and 0.4 μm/h were obtained for MCD and NCD, respectively.
A 3.6 mm diameter drill bit coated in a batch of 7 tools was used to drill a MMC composite (Al-15% Al2O3). The axial cutting forces (Fz) and the tangential forces (Fx and Fy) measured using a tri-axial dynamometer were compared to the cutting forces experienced by an uncoated tool with the same diameter when cutting with the same drilling parameters: feed, f = 0.025 to 0.149 mm/rev; cutting speed, Vc = 25 - 65 m/min and infeed speed, Vf = 110-660 mm/min.
Initially the uncoated tool displays lower Fz values, but more aggressive conditions (high infeed rates) result in the catastrophic failure of the drill bit fracture in the hole, probably due to excessive wear of the cutting edge. The multilayer MCD/NCD coated tool suffered fracture of the cutting edge, probably because of pre-treatment which removes cobalt and reduces its mechanical strength. However, despite the fracture, the diamond film continued to participate in the cutting process, both at the rake face and the exit face, preventing the catastrophic tool failure, unlike to what happens with the uncoated one.
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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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Long, Siyuan. "Cast fibrous MMCs : transfer phenomena and micro-structure formation." Thesis, Imperial College London, 1996. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.362437.
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Karantzalis, Alexander E. "Characterisation of AI MMCs manufactured by a flux casting process." Thesis, University of Nottingham, 1997. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.243346.
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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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Wyatt, Stephen M. "The effect of production route on the mechanical properties and interfacial bond strength of particulate reinforced Al-TiC MMcs." Thesis, University of Nottingham, 2001. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.246368.
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Sarma, Mārtiņš [Verfasser], and R. [Akademischer Betreuer] Stieglitz. "Liquid metal route for creation of metal matrix composites (MMCs) / Mārtiņš Sarma ; Betreuer: R. Stieglitz." Karlsruhe : KIT-Bibliothek, 2020. http://d-nb.info/1221186868/34.
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Rodopoulos, C. A. "Fatigue studies under constant and variable amplitude loading in MMCs." Thesis, University of Sheffield, 1996. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.245575.
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Stone, Ian C. "The characterisation of the spatial distribution of reinforcement in powder metallurgy route Al/SiCp MMCs and its effect on their processing and properties." Thesis, University of Surrey, 1994. http://epubs.surrey.ac.uk/804376/.
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Otani, T. "Corrosion behaviour of metal matrix composite." Thesis, University of Bath, 1988. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.382471.
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DONNINI, RICCARDO. "Metal matrix composite: structure and technologies." Doctoral thesis, Università degli Studi di Roma "Tor Vergata", 2009. http://hdl.handle.net/2108/868.
Full textAbstract:
I compositi a matrice metallica sono materiali aventi elevate potenzialità di applicazione, i cui punti critici riguardano soprattutto le tecnologie di produzione e le lavorazioni alle macchine utensili.
Un composito a matrice di titanio rinforzato con lunghe fibre unidirezionali in SiC, il Ti6Al4V-SiCf, è candidato per componenti di turbine aeronautiche soggette a medie temperature (fino a 600°C) per lunghi tempi di esposizione. Per questo ne sono state esaminate sia le reazioni di tipo microchimico, le quali accadono soprattutto nell’interfaccia fibra/matrice, sia le proprietà meccaniche. La microstruttura allo stato tal quale e dopo lunghi trattamenti termici (fino a 100 ore e 600°C) è stata esaminata mediante diffrazione ai raggi X (XRD), spettrometria elettronica (SEM/EDS), spettroscopia di fotoemissione (XPS) e spettroscopia Auger (AES). Il comportamento meccanico, anche qui sia allo stato tal quale che dopo trattamenti termici, è stato studiato attraverso prove ad indentazione strumentata (FIMEC), di modulo dinamico, prove di trazione e di fatica. Inoltre sono state eseguite prove di frizione interna per verificare il caratteristico comportamento anelastico del materiale, durante condizioni di elevato stato vibrazionale e di alta temperatura. Lo studio, sviluppato sullo stesso composito prodotto però mediante due processi di fabbricazione differenti come Hot Isostatic Pressure and Roll Diffusion Bonding, ha confermato l’idoneità del materiale alle applicazioni considerate.
Per quanto riguarda lo studio della lavorabilità, sono stati studiati, dal punto di vista dell’operazione di foratura, i materiali compositi a matrice di alluminio rinforzati a fibre corte o particolato, valutando le migliori condizioni di riduzione delle forze di taglio, soprattutto in funzione delle temperatura del pezzo da forare.<br>Metal matrix composites are materials having high application potentiality, whose critical points regards especially production technology and machining.
A titanium matrix composite reinforced by unidirectional SiC fibers, Ti6Al4V-SiCf , is candidate to components of aeronautical turbines subjected at middle temperatures (500-600°C) for long exposure time. It has been examined about the micro-chemical reactions, occurring especially on the fiber-matrix interface, and the mechanical properties. The microstructure, in as-fabricated condition and after long-term heat treatments simulating the work condition has been investigated by means of high-temperature X-ray diffraction (XRD), energy dispersion spectrometry (SEM/EDS), X-ray photoelectron spectroscopy (XPS) and Auger electron spectroscopy (AES). The mechanical behaviour, in as-fabricated condition and after heat treatments, have been inspected by instrumented indentation (FIMEC), dynamic modulus, tensile and fatigue tests. Moreover, to the verify the characteristic anelastic phenomena for the composite, internal friction probes have been carried out by using a vibrating reed technique with electrostatic excitation and frequency modulation detection of flexural vibration.
The study has been developed on the same composite produced by two different fabrication process, Hot Isostatic Pressure and Roll Diffusion Bonding, confirming the suitable of the material for the considered applications.
About the composite machining, aluminium matrix composite reinforced by short fiber or particle has been studied about drilling operations, evaluating the better condition to reduce the cutting forces (thrust and torque), especially as function of the workpiece temperature (hot drilling)
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Swaminathan, S. "Processing And Characterisation Of Bulk Al2 O3 p /AIN-Al Composites By Pressureless Infiltration." Thesis, Indian Institute of Science, 2000. https://etd.iisc.ac.in/handle/2005/181.
Full textAbstract:
Al-Mg alloys were infiltrated into porous alumina preforms at temperatures greater than 950°C where significant amount of nitride forms in the matrix. The present work aims to obtain a process window for growing A1N rich composites over uniform thicknesses so that bulk fabrication of these composites could be carried out. Initial experiments were carried out in a thermo-gravimetric analyser (TGA) to establish suitable conditions for growing useful thicknesses. Al- 2wt% Mg alloy, alumina preforms of particle size 53-63μm and N2 - 2% H2 (5ppm O2) were used for the present study based on previous work carried out in the fabrication of MMCs at low temperatures. Experiments carried out in the TGA indicate that oxygen in the system has to be gettered for the growth of nitride rich composites. Infiltration heights of about 8mm were obtained using an external getter (Al - 5wt%Mg) alloy in addition to the base alloy used for infiltration.
The above process conditions were subsequently employed in a tube furnace to fabricate bulk composites and to study the effect of temperature on the volume fraction of aluminium nitride in the matrix. The volume fraction of nitride in the composite varied between 30 and 95 vol % with increase in process temperature from 950°C to 1075°C. Microstructures of these composites indicate that A1N starts to form on the particle surface and tends to grow outwards. The metal supplied through channels adjacent to the particle surface nitride until a point is reached when the composite growing from the adjacent particles meet each other and isolate the melt underneath from nitrogen thereby leading to a metal rich region underneath. Increase in temperature results in an increased nitridation rate resulting in reduced metal pocket size.
Composites fabricated at 975°C had a minor leak at the O-rings, which seal the tube. This led to infiltration under conditions of varying oxygen partial pressure leading to different nitride fractions in the composite. The above fact was confirmed by conducting an experiment with commercial purity nitrogen, which has an oxygen content of about 5000ppm. The composite had an A1N content of about 30% whereas the composite fabricated with N2 -2%H2 (5ppm oxygen) showed a nitride content of 64%. This suggests that one can vary the nitride content in the composite by varying the oxygen content in the system at a particular process temperature.
The hardness of the matrix increases with increase in process temperature from 3.5 ± 0.7 GPa at 975°C to about 9.8 ± 0.9 GPa at 1075°C. Porosity was observed in the composite processed at 1075°C. This increased porosity leads to decreased hardness though the nitride content in the composite has increased by 11%. The scatter in the data is attributed to variations in the microstructure as well as due to interference from underlying metal pockets or particles as well as due to porosity introduced in the composite at high processing temperatures.
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Swaminathan, S. "Processing And Characterisation Of Bulk Al2 O3 p /AIN-Al Composites By Pressureless Infiltration." Thesis, Indian Institute of Science, 2000. http://hdl.handle.net/2005/181.
Full textAbstract:
Al-Mg alloys were infiltrated into porous alumina preforms at temperatures greater than 950°C where significant amount of nitride forms in the matrix. The present work aims to obtain a process window for growing A1N rich composites over uniform thicknesses so that bulk fabrication of these composites could be carried out. Initial experiments were carried out in a thermo-gravimetric analyser (TGA) to establish suitable conditions for growing useful thicknesses. Al- 2wt% Mg alloy, alumina preforms of particle size 53-63μm and N2 - 2% H2 (5ppm O2) were used for the present study based on previous work carried out in the fabrication of MMCs at low temperatures. Experiments carried out in the TGA indicate that oxygen in the system has to be gettered for the growth of nitride rich composites. Infiltration heights of about 8mm were obtained using an external getter (Al - 5wt%Mg) alloy in addition to the base alloy used for infiltration.
The above process conditions were subsequently employed in a tube furnace to fabricate bulk composites and to study the effect of temperature on the volume fraction of aluminium nitride in the matrix. The volume fraction of nitride in the composite varied between 30 and 95 vol % with increase in process temperature from 950°C to 1075°C. Microstructures of these composites indicate that A1N starts to form on the particle surface and tends to grow outwards. The metal supplied through channels adjacent to the particle surface nitride until a point is reached when the composite growing from the adjacent particles meet each other and isolate the melt underneath from nitrogen thereby leading to a metal rich region underneath. Increase in temperature results in an increased nitridation rate resulting in reduced metal pocket size.
Composites fabricated at 975°C had a minor leak at the O-rings, which seal the tube. This led to infiltration under conditions of varying oxygen partial pressure leading to different nitride fractions in the composite. The above fact was confirmed by conducting an experiment with commercial purity nitrogen, which has an oxygen content of about 5000ppm. The composite had an A1N content of about 30% whereas the composite fabricated with N2 -2%H2 (5ppm oxygen) showed a nitride content of 64%. This suggests that one can vary the nitride content in the composite by varying the oxygen content in the system at a particular process temperature.
The hardness of the matrix increases with increase in process temperature from 3.5 ± 0.7 GPa at 975°C to about 9.8 ± 0.9 GPa at 1075°C. Porosity was observed in the composite processed at 1075°C. This increased porosity leads to decreased hardness though the nitride content in the composite has increased by 11%. The scatter in the data is attributed to variations in the microstructure as well as due to interference from underlying metal pockets or particles as well as due to porosity introduced in the composite at high processing temperatures.
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Marcos, Daniel. "Développement de MOULes INNOVants à haute conductivité thermique pour l’injection de matières plastiques fabriquées par Selective Laser Melting (SLM/LBM)." Thesis, Paris Sciences et Lettres (ComUE), 2018. http://www.theses.fr/2018PSLEM080.
Full textAbstract:
Cette thèse a pour objectif de proposer des matériaux adaptés aux attentes d’une empreinte de moule pour l’injection plastique, fabriquée couche par couche par fusion sélective par laser ou « Selective Laser Melting » (SLM). La réalisation d’outillages à haute productivité demande de concevoir des moules à multi-empreintes, à forte dissipation thermique et tenue à l’usure de façon à résister à l’injection de polymères agressifs à haute transition vitreuse et renforcés de fibres de verre. Ces empreintes de moule doivent être à même de supporter de fortes cadences et des cycles thermiques contraignants. La solution proposée dans cette thèse est de travailler sur la mise en forme par SLM de matériaux à haute conductivité thermique et haute dureté. Un premier matériau du commerce répondant partiellement à la demande industrielle a été proposé. Il s’agit d’un acier faiblement allié (42CrMo4). Une caractérisation de la poudre issue d’une atomisation au gaz a été entreprise et ses caractéristiques de mise en couche ont été évaluées. Sa mise en forme par fusion laser a permis d’identifier un ensemble de jeux de paramètres viables, permettant la construction d’inserts à qualité métallurgique satisfaisante. La mise au point d’un traitement thermique approprié vient parfaire l’étude de cet acier. La dernière partie de cette thèse s’attache à proposer le meilleur « design » de poudre pour la mise en forme par SLM de cermets à base WC répondant complétement au cahier des charges industriels. Cette étude reste toutefois exploratoire et se focalise sur l’identification de mécanismes métallurgiques (réactions, changements d’état solide/liquide et liquide/vapeur,…), de phénomènes thermocapillaires et de transports de matière par convection gazeuse<br>The aim of this thesis is to propose materials adapted to the needs of a mold cavity for plastic injection, manufactured layer by layer by "Selective Laser Melting" (SLM). The production of high productivity tools requires the design of multi-cavity molds, with high heat dissipation and wear resistance to resist the injection of aggressive polymers with highglass transition and glass fiber reinforced. These molds must be able to with stand high rates and binding thermal cycles. The solution exposed in this thesis is to work on the fabrication by SLM of materials with high thermal conductivity and high hardness. At first, a commercial material partially meeting industrial demand has been proposed. It is a low alloy steel (42CrMo4). A characterization of the powder from a gas atomization was undertaken and its layering characteristics were evaluated. The experiences, of melting it with a laser, have identified a set of viable parameters, allowing the construction of parts with satisfactory metallurgical quality. The development of a suitable heat treatment completes the studyof this steel. The last part of this thesis consist in a proposition of a "design" of powder for the fabrication by SLM of MetalMatrix Composites, with WC base, fulfilling the industrial specifications. However, this study remains exploratory and focused on the identification of metallurgical mechanisms (reactions, changes in solid / liquid and liquid/ vapor states, etc.), thermo-capillarity phenomena and matter transport by gas convection
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Huang, Ching-Yao. "Applications of Pressure Cycling on Metal Matrix Composite Processing /." The Ohio State University, 1996. http://rave.ohiolink.edu/etdc/view?acc_num=osu1487933648651449.
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Clews, Justin David. "Ultrasonic consolidation of continuous fiber metal matrix composite tape." Access to citation, abstract and download form provided by ProQuest Information and Learning Company; downloadable PDF file, 190 p, 2009. http://proquest.umi.com/pqdweb?did=1885474451&sid=1&Fmt=2&clientId=8331&RQT=309&VName=PQD.
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Smith, Joel Edmund. "Development of improved metal matrix composite via the control of interface and matrix microstructure." Thesis, University of Bath, 1995. https://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.296330.
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Li, Mingshan. "Characterization and modeling of damage in metal matrix composite microstructures /." The Ohio State University, 1998. http://rave.ohiolink.edu/etdc/view?acc_num=osu1487953204282879.
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SHARMA, ANUJ. "DEVELOPMENT, CHARACTERIZATION AND DYNAMIC ANALYSIS OF METAL MATRIX COMPOSITE ROTOR." Thesis, DELHI TECHNOLOGICAL UNIVERSITY, 2021. http://dspace.dtu.ac.in:8080/jspui/handle/repository/18893.
Full textAbstract:
Industrial development is one of the pioneer enablers of the economic and social prosperity
of any nation. High efficiency, low cost and reliable system are the most critical factors
that are focussed by industries. New developments in this direction are observed in the past
few decades. Researchers thrive for new inventions and technologies by which high-quality
output can be attained with effective and robust systems. Materials play an essential role
in achieving high efficiency by providing an outcome-based response to any process. With
the advent of composite materials, industries have started focusing on using lighter weight
materials with the same mechanical properties. Metal matrix composites have the edge
over the parent metals for rotor applications as it has a higher specific modulus and specific
modulus is the critical material factor for vibration responses. Aluminium /alumina MMCs
have shown prominent growth in the composite material market because of their
compatibility with the rotor systems. Several types of research are available for the
development of aluminium based metal matrix composites for industrial applications.
The main focus of this research is to propose a method of development of metal
matrix composite for specific rotary applications. This work focuses on the development,
characterization and dynamic analysis of the metal matrix rotor. The rotors are developed
through a cost-effective, flexible, and readily available method called the stir casting
process.
The physical properties of the composites depend primarily on the homogeneity
and the fraction of reinforcement in the matrix. The uniformity and the concentration have
been enhanced by optimizing process parameters in various researches. However, these
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researches are based on the qualitative analysis (visual observation) of the microstructure
of composites. These qualitative methods do not assist in providing numerical and
objective-oriented results. Therefore, these methods lack a objective judgment that is
crucial for comparing the dispersion of reinforcements consistently. Therefore, quantitative
measurement of dispersion is essential for optimizing the process parameters in order to
attain better results.
There are several techniques for the quantitative measurement of particle dispersion
in the matrix. The mean free path has been calculated by dividing micrograph images into
multiple grid lines and was utilized for quantifying particle dispersions. The quantitative
distribution index and area fraction may be beneficial in optimizing the process parameters
and providing more authentic and reliable results than the qualitative analysis. There are
various methods used for parametric optimization having multivariant parameters. Box-
Behnken designs (BBD) are rotatable or nearly rotatable second-order designs based on
three-level incomplete factorial designs. BBD is one of the main types of response surface
design, the other being central composite design. The BBD design requires a smaller
number of runs as compared to the central composite design. The Box-Behnken design
operates within the range of parameters and does not generate experimentation points
beyond the range of parameters like the central composite design. BBD is suitable for
designs where the range of operations are constrained by manufacturing conditions. In this
work, a novel technique has been adopted where newly developed quantitatively assessed
responses are used for process optimization instead of conventional qualitative analysis
and thus, it provides a profound methodology for optimization of process parameters.
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A novel characterization approach has been adopted in this work, which determines
the effect of reinforcements on the dynamic properties and residual stress of the Al
6061/Al2O3 shafts. Long and slender shafts were fabricated through a stir casting process.
Grain structure has been obtained through optical microscopy, and morphological
evaluation of the composites was performed through Scanning Electron Microscopy
(SEM). In addition to that, an X-ray diffraction pattern (XRD) were analyzed, and residual
stress was calculated by X-ray residual stress measurement system μ-X360 Ver. 2. 3. 0. 1.
Tensile strength and microhardness were also determined in this analysis for various
compositions of the composite material.
For composite materials, the system response changes abruptly with a change in the
properties of the material. Therefore, attaining significant knowledge about the effect of
material composition on material properties is crucial. The researchers are looking for new
computational methods which can predict these alterations so that the effort in
experimental testing can be reduced. In this direction, this paper presents a robust and novel
methodology of validating the estimation of the composite's effective properties through a
multi-scale approach by a set of standardized experimentation. These effective properties
are estimated through the mean-field homogenization technique, whose parameters are
driven from the image analysis of Scanning Electron Microscopy (SEM) images. The
predicted results are validated with the results obtained by the experimentation as per
ASTM E1876 standard.
This research work has adopted a novel approach of providing a dedicated
methodology for determining the calibrated internal damping factor for bond graph
dynamic analysis, which has been used in various literature for transient and stable
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responses. The investigation has been performed on long and slender shafts of the metal
matrix composites. An insight into the change in dynamic response with the difference in
the composition of composite shafts is provided in this work.
Many valuable insights and findings were obtained in this work related to the
development and response of different compositions of metal matrix composite shafts. The
optimization of the stir casting parameters using a quantitative distribution index and area
fraction resulted in uniformly distributed composite shafts. The mechanical properties such
as tensile strength, microhardness, specific modulus increased with the addition of
reinforcement in the composite up to a particular limit. Above that limit, the agglomeration
and porosity become prominent factors and further depletes the properties of a composite.
The natural frequency of the composite shaft increased, and the amplitude of vibration was
reduced for the composites with a high volume fraction of reinforcements. The values of
Young's modulus of different compositions determined through computation were
congruent with the experimental results. The dynamic response was simulated using bond
graph analysis, and it was observed that the amplitude of orbits was also reduced for the
composites with a high volume fraction of reinforcements.
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Evans, Robert David. "Damage evolution and micromechanisms in a small-particle metal matrix composite." Thesis, National Library of Canada = Bibliothèque nationale du Canada, 1999. http://www.collectionscanada.ca/obj/s4/f2/dsk1/tape8/PQDD_0015/NQ42942.pdf.
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Armstrong, William D. "Thermal cycling damage accumulation processes in an advanced metal matrix composite /." Thesis, Connect to this title online; UW restricted, 1991. http://hdl.handle.net/1773/7075.
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Whited, William Thomas. "Microstructural damage evolution during thermal cycling of a metal matrix composite." Thesis, Georgia Institute of Technology, 1992. http://hdl.handle.net/1853/20124.
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Zong, Bernie Yaping. "Strength and fracture of a metal matrix composite at elevated temperature." Thesis, University of Oxford, 1995. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.260733.
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Lee, Yaw Chuan. "Characterisation of the torsional behaviour of titanium metal matrix composite shafts." Thesis, University of Nottingham, 2008. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.594963.
Full textAbstract:
Titanium Metal Matrix Composites (TiMMC) have been gaining momentum in the aerospace applications in the past two decades. The advantages of TiMMC include superior stiffness-ta-weight and strength-ta-weight ratios, compared to conventional aerospace steels. The low pressure shaft in the aeroengine is one of the components that could benefit from the superior material properties of TiMMC. Potentially, the use of TiMMC could provide a combination of higher torque density (higher torque for a given diameter) and lower weight for these shafts. However, little has been done to investigate the torsional behaviour of TiMMC shafts. This thesis investigates the torsional behaviour of TiMMC shafts with different fibre orientations, through experimental tests. A material database was established for the TiMMC system used for each fibre orientation. Further to that, a comprehensive failure investigation was carried out on the tested specimens in order to understand the failure mechanisms. Samples from the fractured specimens were polished and etched to study their microstructure and internal features. Numerical models were developed to predict the global orthotropic elastic material properties of TiMMC using the unit cell concept. The material properties were then used in the tube models which predict the shear moduli for different fibre orientations. The results were validated with the experimental test results. To minnimise weight, aeroengine shafts aim to have thin walls, which could result in buckling instability. Numerical models were therefore developed, to investigate the buckling behaviour of TiMMC shafts. Hill's potential fun ction in ABAQUS was used, which define the anisotropic yield behaviour, using user-defined stress ratios. As a result of this research, the understanding of the torsional behaviour of TiMMC has been strengthened.
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Miotti, Bettanini Alvise. "Welding of high performance metal matrix composite materials: the ICME approach." Thesis, KTH, Metallografi, 2014. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-154021.
Full textAbstract:
The material development cycle is becoming too slow if compared with other technologies sectors like IT and electronics. The materials scientists’ community needs to bring materials science back to the core of human development. ICME (Integrated Computational Materials Engineer) is a new discipline that uses advanced computational tools to simulate material microstructures, processes and their links with the final properties. There is the need for a new way to design tailor-made materials with a faster and cheaper development cycle while creating products that meet “real-world” functionalities rather than vague set of specifications. Using the ICME approach, cutting edge computational thermodynamics models were employed in order to assist the microstructure characterization and refinement during the TIG welding of a functionally graded composite material with outstanding wear and corrosion resistance. The DICTRA diffusion model accurately predicted the carbon diffusion during sintering, Thermo-Calc and TC-PRISMA models described the thermodynamic and kinetics of harmful carbide precipitation, while COMSOL Multhiphysic furnished the temperature distribution profile at every timestep during TIG welding of the material. Bainite transformation and the influence of chromium and molybdenum was studied and modelled with MAP_STEEL software. The simulations were then compared with experimental observations and a very good agreement between computational works and experiments was found for both thermodynamic and kinetics predictions. The use of this new system proved to be a robust assistance to the classic development method and the material microstructures and processes were carefully adjusted in order to increase corrosion resistance and weldability. This new approach to material development can radically change the way we think and we make materials. The results suggest that the use of computational tools is a reality that can dramatically increase the efficiency of the material development.
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Famodimu, Omotoyosi Helen. "Additive manufacturing of aluminium-metal matrix composite developed through mechanical alloying." Thesis, University of Wolverhampton, 2016. http://hdl.handle.net/2436/620337.
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Laser melting of aluminium alloy - AlSi10Mg has increasingly been used to create specialised products in aerospace and automotive applications. However, research on utilising laser melting of Aluminium matrix composites in replacing specialised parts have been slow on the uptake. This has been attributed to the complexity of the laser melting process, metal/ceramic feedstock for the process and the reaction of the feedstock material to the laser. Thus an understanding of the process, material microstructure and mechanical properties is important for its adoption as a manufacturing route of Aluminium Metal Matrix Composites. The effect of the processing parameters (time and speed) on embedding the Silicon Carbide onto the surface of the AlSi10Mg alloy was initially investigated in Phase 1 and 2 of the research. The particle shape and maximum particle size for each milling time and speed was analysed in determining a suitable starting powder for the Laser Melting phase. An ideal shape and size for the composite powder was obtained at 500 rev/min when milled for 20 mins. The effects of several parameters of the Laser Melting process on the mechanical blended composite were investigated. Single track formations of the matrix alloy, 5% Aluminium Metal Matrix Composites and 10% Aluminium Metal Matrix Composites were studied for their reaction to the laser melting in Phase 3. Subsequently in Phase 4, density blocks were studied at different scan speeds and step-over for surface roughness, relative density and porosity. These were utilised in determining a process window to fabricate near fully dense components. Phase 5 of the research focused on microstructural and mechanical properties of the laser melted matrix alloy using the normal parameters for the matrix alloy and the modified LM parameters for the composite powders. Test coupons were built in one orientation and some coupons were heat-treated to initiate precipitation-hardening intermetallics in the matrix and composite. This study investigates the suitability of the mechanical alloying as a novel method of producing feedstock material for the LM process. This research further explores the interaction of the composite powders with the laser until suitable process parameters were obtained. Furthermore, the fractography, mechanical and microstructural evolution of the Al/SiC composite, with different percentage volume reinforcement manufactured by the LM and subsequently heat treated, was explored for the first time.
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Arenburg, Robert Thomas. "Analysis of metal matrix composite structures using a micromechanical constitutive theory." Diss., Virginia Polytechnic Institute and State University, 1988. http://hdl.handle.net/10919/49918.
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The nonlinear behavior of continuous-fiber-reinforced metal-matrix composite structures is examined using a micromechanical constitutive theory. Effective lamina and laminate constitutive relations based on the Aboudi micromechanics theory are presented. The inelastic matrix behavior is modeled by the unified viscoplasticity theory of Bodner and Partom. The laminate constitutive relations are incorporated into a first-order shear deformation plate theory. The resulting boundary value problem is solved by utilizing the finite element method. · Computational aspects of the numerical solution, such as the temporal integration of the inelastic strains and the spatial integration of bending moments are addressed. Numerical results are presented which illustrate the nonlinear response of metal matrix composites subjected to extensional and bending loads. Experimental data from available literature are in good agreement with the numerical results.<br>Ph. D.<br>incomplete_metadata
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Goff, Adam Carter. "Modeling and Synthesis of a Piezoelectric Ceramic-Reinforced Metal Matrix Composite." Thesis, Virginia Tech, 2003. http://hdl.handle.net/10919/10143.
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A mathematical model has been created based on J.D. Eshelby's equivalent inclusion method that can predict the elastic modulus and damping capability in the form of Joule heat for any piezoelectric ceramic-reinforced metal matrix composite system. Specifically, barium titanate (BaTiO₃), lead titanate (PbTiO₃), and zinc oxide (ZnO) piezoelectric ceramics have been modeled as dispersed particles shaped as spheres, prolate spheroids, and discs within a host of common structural metallic matrices including 304 stainless steel, mild steel, aluminum, brass, copper, lead, magnesium, nickel, Ni-20wt%Cr, tin, titanium, Ti-6Al-4V(at%), and tungsten. Composite systems that were predicted to exhibit the greatest level of damping capacity include copper, aluminum, and magnesium matrices reinforced with PbTiO₃, BaTiO₃, and ZnO, in descending order of damping magnitude. In general, higher-conducting, lower-stiffness metallic matrices coupled with more-piezoelectric, higher-stiffness ceramic reinforcement resulted in the greatest level of predicted damping capability and enhanced composite elastic modulus. Additionally, a Ni-20wt%Cr-30v%BaTiO₃ composite has been created using mechanical alloying processing. Specifically, pure constituent powders were combined stoichiometrically in a SPEX milling vial utilizing a charge ratio of 4:1 and subsequently milled for 24 hours. Separate composite powder samples were then annealed in a hydrogen tube furnace at 400°C,
500°C, and 600°C for one and five hours at each temperature. X-ray diffraction was performed on the as-milled and the annealed powders revealing that each was composed of the starting constituents in the appropriate proportions. Representative powders were mounted and polished using common metallographic procedures and microstructures were examined by optical microscopy, scanning electron microscopy, and transmission electron microscopy. All of the powders exhibited a good dispersion of BaTiO₃ particles ranging in diameter from 1μm to about 25nm with no noticeable difference between the as-milled and the annealed powders.<br>Master of Science
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Ward, William F. "A theoretical investigation into the inelastic behavior of metal-matrix composites." Thesis, Georgia Institute of Technology, 1990. http://hdl.handle.net/1853/17244.
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Khan, Kirity Bhusan. "Processing And Characterization Of B4C Particle Reinforced Al-5%Mg Alloy Matrix Composites." Thesis, Indian Institute of Science, 2000. https://etd.iisc.ac.in/handle/2005/182.
Full textAbstract:
Metal matrix composites (MMCs) are emerging as advanced engineering materials for application in aerospace, defence, automotive and consumer industries (sports goods etc.). In MMCs, a metallic base material is reinforced with ceramic fiber, whisker or particulate in order to achieve a combination of properties not attainable by either constituent individually. Aluminium or its alloy is favoured as metallic matrix material because of its low density, easy fabricability and good engineering properties. In general, the benefits of aluminium metal matrix composites (AMCs) over unreinforced aluminium alloy are increased specific stiffness, improved wear resistance and decreased coefficient of thermal expansion. The conventional reinforcement materials for AMCs are SiC and AI2O3.
In the present work, boron carbide (B4C) particles of average size 40μm were chosen as reinforcement because of its higher hardness (very close to diamond) than the conventional reinforcement like SiC, AI2O3 etc. and of its density (2.52 g cm"3) very close to Al alloy matrix. In addition, due to high neutron capture cross-section of 10B isotope, composites containing B4C particle reinforcement have the potential for use in nuclear reactors as neutron shielding and control rod material. Al-5%Mg alloy was chosen as matrix alloy to utilize the beneficial role of Mg in improving wettability between B4C particles and the alloy melt. (Al-5%Mg)-B4C composites containing 10 and 20 vol% B4C particles were fabricated. For the purpose of inter-comparison, unreinforced Al-5%Mg alloy was also prepared and characterized. The Stir Cast technique, commonly utilized for preparation of Al-SiC, was adapted in this investigation.The Composites thus prepared was subsequently hot extruded with the objective of homogenization and healing minor casting defects. Finally the unreinforced alloy and its composites were characterized in terms of their microstructure, mechanical and thermo-physical properties, sliding wear behaviour and neutron absorption characteristics.
The microstructures of the composites were evaluated by both optical microscope and scanning electron microscope (SEM). The micrographs revealed a relatively uniform distribution of B4C particles and good interfacial integrity between matrix and B4C particles.
The hot hardness in the range of 25°C to 500°C and indentation creep data in the range of 300°C to 400°C show that hot hardness and creep resistance of Al-Mg alloy is enhanced by the presence of B4C particles. Measurement of coefficient of thermal expansion (CTE) of composites and unreinforced alloy upto 450°C showed that CTE values decrease with increase in volume fraction of reinforcement.
Compression tests at strain rates, 0.1, 10 and 100 s-1 in the temperature range 25 - 450 °C showed that the flow stress values of composites were, in general, greater than those of unreinforced alloy at all strain rates. These tests also depicted that the compressive strength increases with increase in volume fraction of reinforcements. True stress values of composites and unreinforced alloy has been found to be a strong function of temperature and strain rate. The kinetic analysis of elevated temperature plasticity of composites revealed higher stress exponent values compared to unreinforced alloy. Similarly, apparent activation energy values for hot deformation of composites were found to be higher than that of self-diffusion in Al-Mg alloy.
Tensile test data revealed that the modulus and 0.2% proof stress of composites increase with increase in volume fraction of the reinforcements. Composites containing 10%BUC showed higher ultimate tensile strength values (UTS) compared to unreinforced alloy. However, composites with 20%B4C showed lower UTS compared to that of the unreinforced alloy. This could be attributed to increased level of stress concentration and high level of plastic constraint imposed by the reinforcing jparticles or due to the presence solidification-induced defects (pores and B4C agglomerates ).
Sliding wear characteristics were evaluated at a speed of 1 m/s and at loads ranging from 0.5 to 3.5kg using a pin-on-disc set up. Results show that wear resistance of Al-5%Mg increases with the addition of B4C particles. Significant improvement in wear resistance of Al-5%Mg is achieved with the addition of 20% B4C particles. SEM examination of worn surfaces showed no pull-out of reinforcing particles even at the highest load of 3.5 kg, thus confirming good interfacial bonding between dispersed B4C particles and Al alloy matrix.
The neutron radiography data proved that (Al-5%Mg)-B4C composites possess good neutron absorbing characteristics.
From the experimental data evaluated in the "study, it may be concluded that (Al-5%Mg)-B4C composites could be a candidate material for neutron shielding and control rod application.
The enhanced elevated temperature-strength and favourable neutron absorption characteristics of these composites are strong points in favour of this material.
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Khan, Kirity Bhusan. "Processing And Characterization Of B4C Particle Reinforced Al-5%Mg Alloy Matrix Composites." Thesis, Indian Institute of Science, 2000. http://hdl.handle.net/2005/182.
Full textAbstract:
Metal matrix composites (MMCs) are emerging as advanced engineering materials for application in aerospace, defence, automotive and consumer industries (sports goods etc.). In MMCs, a metallic base material is reinforced with ceramic fiber, whisker or particulate in order to achieve a combination of properties not attainable by either constituent individually. Aluminium or its alloy is favoured as metallic matrix material because of its low density, easy fabricability and good engineering properties. In general, the benefits of aluminium metal matrix composites (AMCs) over unreinforced aluminium alloy are increased specific stiffness, improved wear resistance and decreased coefficient of thermal expansion. The conventional reinforcement materials for AMCs are SiC and AI2O3.
In the present work, boron carbide (B4C) particles of average size 40μm were chosen as reinforcement because of its higher hardness (very close to diamond) than the conventional reinforcement like SiC, AI2O3 etc. and of its density (2.52 g cm"3) very close to Al alloy matrix. In addition, due to high neutron capture cross-section of 10B isotope, composites containing B4C particle reinforcement have the potential for use in nuclear reactors as neutron shielding and control rod material. Al-5%Mg alloy was chosen as matrix alloy to utilize the beneficial role of Mg in improving wettability between B4C particles and the alloy melt. (Al-5%Mg)-B4C composites containing 10 and 20 vol% B4C particles were fabricated. For the purpose of inter-comparison, unreinforced Al-5%Mg alloy was also prepared and characterized. The Stir Cast technique, commonly utilized for preparation of Al-SiC, was adapted in this investigation.The Composites thus prepared was subsequently hot extruded with the objective of homogenization and healing minor casting defects. Finally the unreinforced alloy and its composites were characterized in terms of their microstructure, mechanical and thermo-physical properties, sliding wear behaviour and neutron absorption characteristics.
The microstructures of the composites were evaluated by both optical microscope and scanning electron microscope (SEM). The micrographs revealed a relatively uniform distribution of B4C particles and good interfacial integrity between matrix and B4C particles.
The hot hardness in the range of 25°C to 500°C and indentation creep data in the range of 300°C to 400°C show that hot hardness and creep resistance of Al-Mg alloy is enhanced by the presence of B4C particles. Measurement of coefficient of thermal expansion (CTE) of composites and unreinforced alloy upto 450°C showed that CTE values decrease with increase in volume fraction of reinforcement.
Compression tests at strain rates, 0.1, 10 and 100 s-1 in the temperature range 25 - 450 °C showed that the flow stress values of composites were, in general, greater than those of unreinforced alloy at all strain rates. These tests also depicted that the compressive strength increases with increase in volume fraction of reinforcements. True stress values of composites and unreinforced alloy has been found to be a strong function of temperature and strain rate. The kinetic analysis of elevated temperature plasticity of composites revealed higher stress exponent values compared to unreinforced alloy. Similarly, apparent activation energy values for hot deformation of composites were found to be higher than that of self-diffusion in Al-Mg alloy.
Tensile test data revealed that the modulus and 0.2% proof stress of composites increase with increase in volume fraction of the reinforcements. Composites containing 10%BUC showed higher ultimate tensile strength values (UTS) compared to unreinforced alloy. However, composites with 20%B4C showed lower UTS compared to that of the unreinforced alloy. This could be attributed to increased level of stress concentration and high level of plastic constraint imposed by the reinforcing jparticles or due to the presence solidification-induced defects (pores and B4C agglomerates ).
Sliding wear characteristics were evaluated at a speed of 1 m/s and at loads ranging from 0.5 to 3.5kg using a pin-on-disc set up. Results show that wear resistance of Al-5%Mg increases with the addition of B4C particles. Significant improvement in wear resistance of Al-5%Mg is achieved with the addition of 20% B4C particles. SEM examination of worn surfaces showed no pull-out of reinforcing particles even at the highest load of 3.5 kg, thus confirming good interfacial bonding between dispersed B4C particles and Al alloy matrix.
The neutron radiography data proved that (Al-5%Mg)-B4C composites possess good neutron absorbing characteristics.
From the experimental data evaluated in the "study, it may be concluded that (Al-5%Mg)-B4C composites could be a candidate material for neutron shielding and control rod application.
The enhanced elevated temperature-strength and favourable neutron absorption characteristics of these composites are strong points in favour of this material.
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Drury, William James. "Quantitative microstructural and fractographic characterization of AE-Li/FP metal matrix composite." Thesis, Georgia Institute of Technology, 1988. http://hdl.handle.net/1853/19958.
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Madgwick, Alexander. "Creep and damage in an A359 aluminium alloy/SiC metal matrix composite." Thesis, University of Cambridge, 2002. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.620311.
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Hansen, Robert C. "Thermal and mechanical fatigue of 6061 Al - P100 Gr metal matrix composite." Thesis, Monterey, California : Naval Postgraduate School, 1990. http://handle.dtic.mil/100.2/ADA238795.
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Thesis (M.S. in Mechanical Engineering)--Naval Postgraduate School, September 1990.<br>Thesis Advisor(s): Dutta, Indranath ; Mitra, Shantanu. "September 1990." Description based on title screen as viewed on December 21, 2009. DTIC Identifier(s): Fatigue (mechanics), thermal fatigue, metal matrix composites, laminates, bending, ultimate strength, fiber reinforced composites, theses. Author(s) subject terms: Aluminum-graphite composite, bend fatigue, thermal fatigue. Includes bibliographical references (p. 64-65). Also available in print.