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1
Hihara, Lloyd Hiromi. "Corrosion of aluminum-matrix composites." Thesis, Massachusetts Institute of Technology, 1989. http://hdl.handle.net/1721.1/14332.
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Thesis (Ph. D.)--Massachusetts Institute of Technology, Dept. of Chemical Engineering, 1989.Videocassette is VHS format. Vita.
Includes bibliographical references.
by Lloyd Hiromi Hihara.
Ph.D.
2
Dibelka, Jessica Anne. "Mechanics of Hybrid Metal Matrix Composites." Diss., Virginia Tech, 2013. http://hdl.handle.net/10919/50579.
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The appeal of hybrid composites is the ability to create materials with properties which normally do not coexist such as high specific strength, stiffness, and toughness. One possible application for hybrid composites is as backplate materials in layered armor. Fiber reinforced composites have been used as backplate materials due to their potential to absorb more energy than monolithic materials at similar to lower weights through microfragmentation of the fiber, matrix, and fiber-matrix interface. Composite backplates are traditionally constructed from graphite or glass fiber reinforced epoxy composites. However, continuous alumina fiber-reinforced aluminum metal matrix composites (MMCs) have superior specific transverse and specific shear properties than epoxy composites. Unlike the epoxy composites, MMCs have the ability to absorb additional energy through plastic deformation of the metal matrix. Although, these enhanced properties may make continuous alumina reinforced MMCs advantageous for use as backplate materials, they still exhibit a low failure strain and therefore have low toughness. One possible solution to improve their energy absorption capabilities while maintaining the high specific stiffness and strength properties of continuous reinforced MMCs is through hybridization. To increase the strain to failure and energy absorption capability of a continuous alumina reinforced Nextel" MMC, it is laminated with a high failure strain Saffil® discontinuous alumina fiber layer. Uniaxial tensile testing of hybrid composites with varying Nextel" to Saffil® reinforcement ratios resulted in composites with non-catastrophic tensile failures and an increased strain to failure than the single reinforcement Nextel" MMC. The tensile behavior of six hybrid continuous and discontinuous alumina fiber reinforced MMCs are reported, as well as a description of the mechanics behind their unique behavior. Additionally, a study on the effects of fiber damage induced during processing is performed to obtain accurate as-processed fiber properties and improve single reinforced laminate strength predictions. A stochastic damage evolution model is used to predict failure of the continuous Nextel" fabric composite which is then applied to a finite element model to predict the progressive failure of two of the hybrid laminates.Ph. D.
3
Kamat, Samir V. "Fracture toughness of particulate-reinforced aluminum-matrix composites /." The Ohio State University, 1988. http://rave.ohiolink.edu/etdc/view?acc_num=osu1487592050230594.
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Kolli, Sudhakar. "Joining of aluminum based particulate-reinforced metal-matrix composites /." The Ohio State University, 1991. http://rave.ohiolink.edu/etdc/view?acc_num=osu1487685204967.
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Chen, Yong-Ching. "Elevated temperature deformation and forming of aluminum-matrix composites /." The Ohio State University, 1991. http://rave.ohiolink.edu/etdc/view?acc_num=osu1487758178238026.
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Keles, Ozgur. "Production And Characterization Of Alumina Fiber Reinforced Squeeze Cast Aluminum Alloy Matrix Composites." Master's thesis, METU, 2008. http://etd.lib.metu.edu.tr/upload/12609726/index.pdf.
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The aim of the present study was to investigate the effects of different levels of Saffil alumina fiber addition, magnesium content in aluminum alloy matrix and casting temperature on the mechanical behavior, microstructure and physical properties of short fiber reinforced aluminum matrix composites. The main alloying element silicon was kept constant at 10 wt%. Magnesium contents were selected as 0.3 wt% and 1 wt%. Saffil alumina fiber preforms varied from 10 to 30 vol%. The casting temperatures were fixed at 750 °C and 800 °
C. Micro porosity was present at the fiber-fiber interactions. Closed porosity of the composites increased when fiber vol% increased, however, variation in casting temperature and magnesium content in matrix did not have influence on porosity. Hardness of the composites was enhanced with increasing fiber vol%, magnesium content in matrix and decreasing casting temperature. Alignment of fibers within the composite had an influence on hardness
when fibers were aligned perpendicular to the surface, composites exhibited higher hardness. The highest hardness values obtained from surfaces parallel and vertical to fiber orientation were 155.6 Brinell hardness and 180.2 Brinell hardness for AlSi10Mg1 matrix 30 vol% alumina fiber reinforced composite cast at 800 °
C and at 750 °
C, respectively. 30 vol% Saffil alumina fiber reinforced AlSi10Mg0.3 matrix composite cast at 750 °
C showed the highest flexural strength which is 548 MPa. Critical fiber content was found as 20 vol% for all composites.
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Allen, Susan Marie. "Effect of alumina particle additions of the aging kinetics of 6061 aluminum matrix composites." Thesis, Monterey, California : Naval Postgraduate School, 1990. http://handle.dtic.mil/100.2/ADA238052.
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Thesis (M.S. in Mechanical Engineering)--Naval Postgraduate School, June 1990.Thesis Advisor(s): Dutta, I. "June 1990." Description based on title screeen viewed on October 15, 2009. DTIC Descriptor(s): Scanning, aging(materials), composite materials, growth(general), thermal stability, phase, particles, aluminum oxides, electrical resistance, kinetics, hardness, metastable state, isotherms, calorimetry, protective treatments, addition, measurement DTIC Indicator(s): Aluminum matrix composites. Author(s) subject terms: Aluminum matrix composites. Includes bibliographical references (p. 54-56). Also available in print.
8
Yu, Hao. "Processing Routes for Aluminum based Nano-Composites." Digital WPI, 2010. https://digitalcommons.wpi.edu/etd-theses/367.
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The term "Metal Matrix Nano-Composites (MMNCs)" broadly refers to a composite system that is based on metal or alloy substrate, combined with metallic or non-metallic nano-scale reinforcements. The main advantages of MMNCs include excellent mechanical performance, feasible to be used at elevated temperatures, good wear resistance, low creep rate, etc. In the recent past, MMNCs have been extensively studied, especially the method of fabrication as the processing of such composites is quite a challenge. Though a variety of processing methods have been explored and studied over the years, none have emerged as the optimum-processing route. The major issue that needs to be addressed is the tendency of nano-sized particles to cluster and also the challenge as to how to disperse them in the bulk melt. This work explored the feasibility of utilizing Lorentz forces to address both of these critical issues: clustering and dispersion. The work was carried out both theoretically as well as with accompanying validation experiments. The results indicate that Lorentz Forces may be viable and should be considered in the processing of MMNCs.
9
Hunt, Michael Patrick. "Pressureless Densification of Alumina - Titanium Diboride Ceramic Matrix Composites." Thesis, Virginia Tech, 2009. http://hdl.handle.net/10919/31326.
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The research focus was to determine diffusion mechanisms responsible for densification behavior of SHS produced Al2O3/TiB2 Ceramic Matrix Composites (CMCs). Previous research has shown SHS produced Al2O3/TiB2 composites exhibited unique microstructural properties that contributed to high strength, fracture toughness, and hardness properties. Pressureless densification of SHS produced Al2O3/TiB2 composites would provide a cost savings because the equipment for pressureless densification is less expensive and less complicated than equipment required for densification with pressure.
Models for sintering of CMCs and calculation of Sintering Time Constants (STC) were used to predict the densification behavior of the SHS produced Al2O3/TiB2 composite. The Levin, Dirnfeld, Shwam equation was used to determine the Rate Controlling Diffusion Mechanism (RCDM) and activation energy for sintering. X-Ray Diffraction (XRD) analysis of the as-milled reaction product powder revealed the presence of an aluminum borate (Al18B4O33) as a third phase, as well as, in pressureless heat treated samples. Based on experimental results and analysis, it seemed possible the Al18B4O33 compound may have formed by reaction of Al2O3 with TiB2 along their interfaces. Aluminum borates have been observed to form Al18B4O33 (s) + B2O3 (l) at temperatures above 1000°C. The RCDM for densification of SHS produced Al2O3/TiB2 was found to be liquid phase diffusion with volume diffusion also likely being active during densification. In addition, Al18B4O33 seemed to be the preferred compound formed during oxidation. Further research should be performed to control formation of Al18B4O33; as well as, on the oxidation behavior of the SHS produced Al2O3/TiB2.Master of Science
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Li, Wei. "FABRICATION OF ALUMINUM MATRIX PARTICULATE COMPOSITES BY COMPACTION AND SINTERING." MSSTATE, 2008. http://sun.library.msstate.edu/ETD-db/theses/available/etd-11062008-150028/.
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With the possession of extremely broad unique properties, particulate reinforced aluminum composites are very attractive in diverse applications. Aluminum matrix particulate composites are challenging to work with. A single pressing and sintering process was used to fabricate the reinforced aluminum composites in this study. The key advantage of this method is its comparative low expense. However, abrasive reinforcement powders can lead to shorter tool life. To study the fundamental wear mechanisms during the die compaction process, a new method was developed and combined with experiments to quantify tool wear. Automatic die compaction experiments and tribological experiments are employed in this study. The tribologcial experiments consist of a modified pin-on-flat test and a modified loop test. Mass loss of tools was recorded during all the experiments. A new tool wear model was used in this study to investigate effect of different hard phase and different lubricant level on die compaction process.
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Harper, Christopher Paul. "Effect of alumina particle additions on the aging kinetics of 2014-aluminum matrix composites." Thesis, Monterey, California. Naval Postgraduate School, 1991. http://hdl.handle.net/10945/26510.
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Differential Scanning Calorimetry (DSC) was conducted on 2014 aluminum, 2014 aluminum reinforced with 10 and 15 percent by volume of alumina particles, 2024 aluminum, and a A1/4%Cu alloy. Electrical resistivity and matrix micro-hardness measurements were conducted on the 2014 aluminum alloy and the metal matrix composites (MMC) during isothermal aging. Transmission Electron Microscopy (TEM) and DSC were used to identify the metastable phases formed in the 2014 aluminum alloy. The effect of alumina particle addition on the precipitation, growth and thermal stability of the metastability phases in the 2014 aluminum alloy and MMC were studied. Results were used to characterize the effect of the alumina reinforcement on the aging kinetics of the 2014 aluminum alloy matrix
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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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Kothari, Mitul Arvind. "Welding of cast A359/SiC/10p metal matrix composites." Texas A&M University, 2005. http://hdl.handle.net/1969.1/2699.
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Welding of metal matrix composites (MMCs) is an alternative to their
mechanical joining, since they are difficult to machine. Published literature in fusion
welding of similar composites shows metallurgical problems. This study investigates the
weldability of A359/SiC/10p aluminum SiC MMC. Statistical experiments were
performed to identify the significant variables and their effects on the hardness, tensile
and bending strengths, ductility, and microstructure of the weld. Finite Element
Analysis (FEA) was used to predict the preheat temperature field across the weld and the
weld pool temperature.
Welding current, welding speed, and the preheat temperature (300-350??C)
affected the weld quality significantly. It was seen that the fracture of the welded
specimens was either in the base MMC or in the weld indicating a stronger interface
between the weld and the base MMC. Oxides formation was controlled along the weld
joint. Low heat inputs provided higher weld strengths and better weld integrity. It was
found that the weld strengths were approximately 85% of the parent material strength.
The weld region had higher extent of uniform mixing of base and filler metal when
welded at low currents and high welding speeds. These adequate thermal conditions
helped the SiC particles to stay in the central weld region. The interface reaction
between the matrix and SiC particles was hindered due to controlled heat inputs and
formation of harmful Al4C3 flakes was suppressed. The hardness values were found to
be slightly higher in the base metal rich region. There was no significant loss in the
hardness of the heat affected zone. The ductility of the weld was considerably increased
to 6.0-7.0% due to the addition of Al-Si filler metal.
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Miller, David N. "The sintering of a-alumina reinforced aluminium alloy matrix composites / y David N. Miller." [St. Lucia, Qld], 2004. http://www.library.uq.edu.au/pdfserve.php?image=thesisabs/absthe18280.pdf.
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Cetin, Arda. "Assessment And Modelling Of Particle Clustering In Cast Aluminum Matrix Composites." Phd thesis, METU, 2008. http://etd.lib.metu.edu.tr/upload/12609456/index.pdf.
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The damage and deformation behaviour of particle reinforced aluminum matrix composites can be highly sensitive to local variations in spatial distribution of reinforcement particles, which markedly depend on melt processing and solidification
stages during production. The present study is aimed at understanding the mechanisms responsible for clustering of SiC particles in an Al-Si-Mg (A356) alloy composite during
solidification process and establishing a model to predict the risk of cluster formation as a function of local solidification rate in a cast component. Special emphasis has been given
to spatial characterization methods in terms of their suitability to characterize composite microstructures. Result indicate that methods that present a summary statistics on the
global level of heterogeneity have limited application in quantitative analysis of discontinuously reinforced composites since the mechanical response of such materials are
highly sensitive to dimensions, locations and spatial connectivities of clusters. The local density statistics, on the other hand, was observed to provide a satisfactory description of the microstructure, in terms of localization and quantification of clusters. A macrotransport - solidification kinetics model has been employed to simulate solidification microstructures for estimation of cluster formation tendency. Results show that the distribution of SiC particles is determined by the scale of secondary dendrite arms (SDAS). In order to attain the lowest amount of particle clustering, the arm spacings should be kept within the limit of 2dSiC >SDAS >
dSiC, where dSiC is the average particle diameter.
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Park, Conrad. "Mechanical Performance and Structure-Property Relations in6061B Aluminum Metal Matrix Composites." Case Western Reserve University School of Graduate Studies / OhioLINK, 2019. http://rave.ohiolink.edu/etdc/view?acc_num=case1547842396716777.
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Ren, Zheng Materials Science & Engineering Faculty of Science UNSW. "Mechanical properties of 7075 aluminium matrix composites reinforced by nanometric silicon carbide particulates." Awarded by:University of New South Wales, 2007. http://handle.unsw.edu.au/1959.4/34742.
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Aluminium composites reinforced by particles have received considerable attention because of their superior mechanical properties over monolithic aluminum matrix. Over the last ten years, nanocomposites with nano-sized reinforcements have become a revolutionary progress for composites because they have different strengthening mechanisms as compared to that in composites with micro-sized reinforcements. Consequently novel properties can be expected from the nanometric particulate reinforced composites. The aim of this project was to fabricate SiC (50nm)/7075 aluminium composites via a modified powder metallurgy and extrusion route. Ageing treatment was used to increase the strength of the composites and mechanical tests, including tensile test and abrasive wear test, were performed. The effects of nanometric silicon carbide particulates to the ageing behaviours and mechanical properties of the composites have been studied by optical metallography, scanning electron microscopy and transmission electron microscopy. It was found that the dispersion of nanometric silicon carbide was not homogeneous, but tended to disperse along grain boundaries. Clustering of these nano-reinforcements was also found within the grains. This was particular true when the amount of nano-reinforcement increased to 5%. Compared with the monolithic 7075 alloy, the 1 vol.% SiC (50nm)/7075 aluminium had a higher strength because of effective dislocation pinnings by the reinforcements, while 5% SiC (50nm)/7075 had a much lower strength and ductility because of severe aggregation of nanometric particulates. Nanometric silicon carbide was not as effective as the micro ones in improving abrasive wear resistance of aluminium, this was because of micro-cracking in the aggregation and relatively large abrasive grit. In summary, the addition of a small amount of SiC nanoreinforcements has a high potential to further strengthen 7xxx aluminium alloy. However, the clustering of reinforcements in the matrix will detrimentally affect the strength and ductility of the alloy. The wear resistance of nanometric particulate reinforced composites was inferior to those with micrometric reinforcements. It is suggested that by improving the dispersion of nanometric reinforcements, as well as putting in reinforcememts with different sizes, the mechanical properties and wear resistance can both be increased.
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Rozak, Gary Alan. "Effects of processing on the properties of aluminum and magnesium matrix composites." Case Western Reserve University School of Graduate Studies / OhioLINK, 1993. http://rave.ohiolink.edu/etdc/view?acc_num=case1057068629.
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Dash, Lawrence Christopher. "The mechanism of corrosion and corrosion control of aluminum/graphite metal matrix composites /." The Ohio State University, 1988. http://rave.ohiolink.edu/etdc/view?acc_num=osu1487588249825594.
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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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Ali, Fahad. "Mechanical milling of Al-Cu-Fe quasicrystals and their Reinforcement in Aluminum matrix composites." Doctoral thesis, Saechsische Landesbibliothek- Staats- und Universitaetsbibliothek Dresden, 2012. http://nbn-resolving.de/urn:nbn:de:bsz:14-qucosa-85895.
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In this thesis, the effect of mechanical deformation on structure, thermal stability and hardness of a single-phase spray-deposited quasicrystalline alloy with composition Al62.5Cu25Fe12.5 has been investigated in detail. The purpose of the investigation was to study the effect of mechanical milling at different milling speeds (which approximately scale with the milling intensity) on mechanically-induced phase transformations during milling and on the phase evolution during subsequent heating.
The results of the milling experiments indicate that, irrespective of the milling speeds used, mechanical milling of Al62.5Cu25Fe12.5 quasicrystals leads to the formation of a disordered CsCl-type ß phase with grain size of about 10 – 20 nm. The analysis of the kinetics of the QC–to–ß phase transformation reveals that the milling intensity has a considerable effect on the characteristics of the transformation. The increase of the milling speed considerably shortens the incubation time needed to start the QC–to–ß phase transformation. Also, the overall transformation is much faster for milling at high speeds.
The QC–to–ß phase transformation starts when the grain size of the quasicrystals is reduced to about 10 nm irrespective of the milling speed used and clearly indicates that a critical grain size of the quasicrystals for initiating the transformation exists. On the other hand, no critical value of lattice strain was found for the QC–to–ß transformation. This indicates that the phase transformation is controlled by the local length scale (i.e. the grain size) and by the corresponding grain boundaries rather than by the energy stored in the lattice.
Energetic considerations obtained through a simple model based on the mass and velocity of the milling balls reveal that the energy needed for the QC–to–ß transformation increases with increasing the milling speed, that is, the energetic efficiency of the process decreases with increasing the milling intensity. This indicates that part the extra energy supplied during milling at high intensities is not used to induce the phase transformation but it is dissipated by heat.
During heating, the milled powder displays a multi-step thermal behavior characterized by the grain growth of the disordered ß phase at low temperatures, followed, at higher temperatures, by its transformation into the original icosahedral quasicrystalline phase. The transformation is gradual and the quasicrystals and the disordered ß phase coexist over a temperature interval of more than 250 K.
The phase transformations occurring during milling and subsequent annealing have a remarkable effect on the hardness, which can be tuned within a wide range of values (7–9.6 GPa) as a function of the volume fraction of the different phases. This suggests that a composite material with optimized mechanical properties can be produced by an appropriate thermo-mechanical treatment.
The quasicrystals milled at a very low speed show a transition between Hall-Petch to inverse Hall-Petch behavior at a grain size of about 40 nm, which represents the critical value for grain size softening of the present Al62.5Cu25Fe12.5 quasicrystals. This behavior may be attributed to the complexity of the quasicrystalline structure and to its peculiar deformation mechanism at room temperature (i.e. shear banding), where meta-dislocation-assisted deformation is almost absent.
In order to analyze the effectiveness of the Al62.5Cu25Fe12.5 quasicrystals as reinforcing agent in metal matrix composites, Al-based composites were synthesized by hot extrusion of elemental Al blended with different amounts of Al62.5Cu25Fe12.5 quasicrystalline particles. The work was focused on two specific aspects: evaluation of the mechanical properties through room temperature compression tests and modeling of the resulting properties. The addition of the quasicrystalline reinforcement is very effective for improving the room temperature mechanical properties of pure Al. The compressive strength increases from 155 MPa for pure Al to 330 and 407 MPa for the composites with 20 and 40 vol.% of reinforcement, respectively, reaching an ultimate strain of 55 % and 20 % before fracture occurs. These results indicate that the addition of the QC reinforcement leads to composite materials with compressive strengths exceeding that of pure Al by a factor of 2 – 2.5, while retaining appreciable plastic deformation.
The mechanical properties of the composites have been modeled by taking into account the combined effect of load bearing, dislocation strengthening and matrix ligament size effects. The calculations are in very good agreement with the experimental results and reveal that the reduction of the matrix ligament size, which results in a similar strengthening effect as that observed for grain refinement, is the main strengthening mechanism in the current composites.
Finally, the interfacial reaction between the Al matrix and the QC reinforcement has been used to further enhance the strength of the composites through the formation of a new microstructure consisting of the Al matrix reinforced with Al7Cu2Fe w-phase particles. The optimization of the structure-property relationship was done through the systematic variation of the processing temperature during consolidation. The mechanical behavior of these transformation-strengthened composites is remarkably improved compared to the parent material. The yield strength of the composites significantly increases as the Al + QC -> ω transformation progresses from 195 MPa for the sample reinforced only with QC particles to 400 MPa for the material where the Al + QC -> ω reaction is complete.
These results clearly demonstrate that powder metallurgy, i.e. powder synthesis by ball milling followed by consolidation into bulk specimens, is an attractive processing route for the production of novel and innovative lightweight composites characterized by high strength combined with considerable plastic deformation. In addition, these findings indicate that the mechanical behavior of Al-based composites reinforced with Al62.5Cu25Fe12.5 quasicrystalline particles can be tuned within a wide range of strength and plasticity depending on the volume fraction of the reinforcement as well as on the extent of the interfacial reaction between Al matrix and QC reinforcing particles.
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Uribe, Restrepo Catalina. "Process-dependent microstructure and severe plastic deformation in SiCp?? reinforced aluminum metal matrix composites." Master's thesis, University of Central Florida, 2011. http://digital.library.ucf.edu/cdm/ref/collection/ETD/id/4712.
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Discontinuously reinforced MMCs with optimized microstructure are sought after for exceptional high strain rate behavior. The microstructure evolution of a stir-cast A359 aluminum composite reinforced with 30 vol.% SiCsubscript p] after isothermal anneal, successive hot-rolling, and high strain rate deformation has been investigated. Quantitative microstructural analysis was carried out for the as-cast, annealed (470??C, 538??C and 570??C) and successively hot rolled specimens (64, 75, 88, and 96% rolling reductions). Selected composites were also examined after high strain rate deformation. X-ray diffraction, optical microscopy, scanning electron microscopy and transmission electron microscopy were employed for microstructural characterization. The strength and ductility of the A359 Al alloys, and the composite, were greatly influenced by the brittle eutectic silicon phase and its morphology. Lamellar eutectic silicon spheroidized with isothermal anneal and successive hot rolling with a corresponding decrease in hardness. The hot rolling process also considerably decreased the SiC particle size (approximately 20% after 96% reduction) by breaking-up the hard SiC particles. However, this break-up of particles increased the homogeneity of SiCsubscript p] size distribution. Successive hot rolling also healed voids due to solidification shrinkage, incomplete infiltration of molten Al and defects originating from fractured particles. Four selected specimens of composites were examined after high strain rate deformation. Fractography and metallographic analysis for the craters, voids, and relevant regions affected by the high velocity impact were carried out. The deposition of impact residuals was frequently observed on the exposed fracture surfaces. These residuals were typically observed as "molten-and-solidified" as a consequence of excessive heat generated during and after the damage.; Particularly in regions of entry and exit of impact, intermixing of residuals and composite constituents were observed, demonstrating that the Al matrix of the composite also had melted. In all samples examined, cracks were observed to propagate through the eutectic Si network while a small number of broken reinforcement particles were observed. A slight variation in failure mechanisms was observed (e.g., radial, fragmentation, petalling) corresponding to the variation in ductility against high strain rate deformation. In selected specimens, parallel sub-cracks at the exit were observed at 45?? and 30??. These sub-cracks were again filled with intermixed constituents from projectile residuals and composites. This observation suggests that the melting of composite constituents that leads to intermixing occured after the crack propagation and other damage.ID: 030646232; System requirements: World Wide Web browser and PDF reader.; Mode of access: World Wide Web.; On t.p. "p??" is subscript.; Thesis (M.S.M.S.E.)--University of Central Florida, 2011.; Includes bibliographical references (p. 86-88).
M.S.M.S.E.
Masters
Materials Science Engineering
Engineering and Computer Science
Materials Science and Engineering
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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
iii
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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Turkyilmaz, Gokhan. "Processing And Assessment Of Aluminum Ceramic Fiber Reinforced Aluminum Metal Matrix Composite Parts For Automotive And Defense Applications." Master's thesis, METU, 2009. http://etd.lib.metu.edu.tr/upload/12610751/index.pdf.
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The aim of this study was to produce partially reinforced aluminum metal matrix
composite components by insertion casting technique and to determine the effects
of silicon content, fiber vol% and infiltration temperature on the mechanical
properties of inserts, which were the local reinforcement parts of the components.
Silicon content of alloys was selected as 7 wt% and 10 wt%. The reinforcement
material, i.e. Saffil fiber preforms, had three different fiber vol% of 20, 25 and 30
vol% respectively. The infiltration temperatures of composite specimens were fixed
as 750 °C and 800 °
C. In the first part of the thesis, physical and mechanical properties of composite specimens were determined according to the parameters of silicon content of the matrix alloy, infiltration temperature and vol% of the reinforcement phase. X-ray diffraction examination of fibers resulted as the fibers mainly composed of deltaalumina fibers and scanning electron microscopy analyses showed that fibers had planar isotropic condition for infiltration. Microstructural examination of composite specimens showed that appropriate fiber/matrix interface was created together with small amount of micro-porosities. Bending tests of the composites showed that as fiber vol% increases flexural strength of the composite increases. The highest strength obtained was 880.52 MPa from AlSi10Mg0.8 matrix alloy reinforced with 30 vol% Saffil fibers and infiltrated at 750 °
C. Hardness values were also increased by addition of Saffil fibers and the highest value was obtained as 191 HB from vertical to the fiber orientation of AlSi10Mg0.8 matrix alloy reinforced with 30 vol% Saffil fibers. Density measurement revealed that microporosities existed in the microstructure and the highest difference between the theoretical values and experimental values were observed in the composites of 30 vol% Saffil fiber reinforced ones for both AlSi7Mg0.8 and AlSi10Mg0.8 matrix alloys. In the second part of the experiments, insertion casting operation was performed. At casting temperature of 750 °
C, a good interface/component interface was obtained. Image analyses were also showed that there had been no significant fiber damage between the insert and the component.
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Butler, Joseph Edmund. "In-situ Fiber Strength Distribution in NextelTM 610 Reinforced Aluminum Composites." Thesis, Virginia Tech, 2006. http://hdl.handle.net/10919/32433.
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MetPreg, a composite developed by Touchstone Research Laboratories (Tridelphia, WV), is an aluminum metal matrix composite reinforced by continuous NextelTM 610 alumina fibers. The question is, after processing, are the NextelTM fibers affected in any way that their strengthening contribution to the composite is reduced? From experimentation and statistical analysis, a strength distribution of pre-processed NextelTM 610 fibers is formed and an empirical correlation is developed relating strength to the observed flaw size on the failed single fibers. This correlation is then independently applied to flaw size information gathered from fibers on the fracture surface of MetPreg samples to develop a separate strength distribution of post-processed NextelTM 610 fibers. The pre- and post-processed distributions are compared to one another to determine the effect, if any, that composite processing has on the strength of NextelTM 610 fibers. The results indicate that the in-situ strength distribution of fibers was increased by composite processing.Master of Science
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Yilmaz, Hamdi Sencer. "Characterization Of Silicon Carbide Particulate Reinforced Squeeze Cast Aluminum 7075 Matrix Composite." Master's thesis, METU, 2004. http://etd.lib.metu.edu.tr/upload/3/12605261/index.pdf.
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The aim of this study is to investigate the mechanical behavior and its relation with processing and microstructure of the silicon carbide particulate (SiCp) reinforced aluminum matrix composite. Aluminum 7075 alloy is chosen as matrix alloy, in which zinc is the main alloying element. Four different additions of SiCp were used and the weight fractions were 10%, 15%, 20% and 30%. Composites were processed by with squeeze casting and the applied pressure during casting was 80 MPa. The mould is specially designed to produce both specimens ready for tensile and three point bending tests.
Both as-cast and heat treated aluminum composites were examined and T6 heat treatment was applied. Three point bending tests were performed to reveal the fracture strength of aluminum composites. 10wt% SiCp aluminum composites showed the maximum flexural strength in both as-cast and heat treated composites. The mechanical test results revealed that precipitated phases in heat treated composites, behaved like fine silicon carbide particulates and they acted as barriers to dislocation motion. Maximum flexural strength increased about 40 MPa (10%) in as-cast and 180 MPa (44%) in heat treated composites. Tensile testing was also conducted to verify the results of the three point bending tests.
Hardness tests were done to find the effect of silicon carbide addition and to find the peak hardness in heat treatment. For as-cast specimens hardness values increased from 133 to 188 Vickers hardness (10 kg.) with increase in SiCp content from 0 to 30wt% and for heat treatment specimens hardness values increased from 171 to 221 Vickers hardness (10 kg.). The peak hardness values were obtained at 24 hours precipitation heat treatment. SEM studies were carried out to examine the heat treated composites, to take SEM photographs and to obtain a general elemental analysis. Theoretical volume percentage addition of SiCp was checked with Clemex Image Analyzer program. Distribution of SiCp was determined by mettalographic examination. Second phases that were formed during heat treatment was searched by x-ray analysis.
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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.M.S.M.S.E.
Masters
Materials Science Engineering
Engineering and Computer Science
Materials Science and Engineering; Accelerated BS to MS
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Durkin, Craig Raymond. "Low-Cost Continuous Production of Carbon Fiber-Reinforced Aluminum Composites." Thesis, Georgia Institute of Technology, 2007. http://hdl.handle.net/1853/19857.
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The research conducted in this study was concerned with the development of low-cost continuous production of carbon fiber/aluminum composites. Two coatings, alumina and zirconia, were applied to the fibers to protect against interfacial degradation. They were applied using a sol-gel method and common metal salts. The fibers were infiltrated with molten aluminum using an ultrasound sonicator. The resultant composites were well-infiltrated and were tested in tension to determine their mechanical properties. Strengths were only 15-35% of the theoretical values predicted by the rule of mixtures. The composite microstructure revealed a sizable void fraction and that the fibers within the composites did not contain any coating on their surface. It was hypothesized that this was a result of few exposed graphite plane edges on the fiber surface, causing poor adhesion of the oxide coating to the fiber surface. To improve adhesion, an amorphous carbon coating was applied to the fiber surface, but still the oxide coatings were removed from the fibers upon infiltration. It was found, however, that the carbon coating on its own did strengthen the interface between the fiber and the aluminum.
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Evarts, Jonathan S. "Advanced Processing Techniques For Co-Continuous Ceramic Composites." The Ohio State University, 2008. http://rave.ohiolink.edu/etdc/view?acc_num=osu1218218162.
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Lu, Xiuqing, and 卢秀清. "Phase transformations and leaching behavior of hazardous zinc stabilized in aluminum-based ceramic products." Thesis, The University of Hong Kong (Pokfulam, Hong Kong), 2015. http://hdl.handle.net/10722/212624.
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Karakas, Mustafa Serdar. "Effect Of Aging On The Mechanical Properties Of Boron Carbide Particle Reinforced Aluminum Metal Matrix Composites." Phd thesis, METU, 2007. http://etd.lib.metu.edu.tr/upload/2/12608944/index.pdf.
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Metal matrix composites (MMCs) of Al - 4 wt.% Cu reinforced with different volumetric fractions of B4C particles were produced by hot pressing. The effect of aging temperature on the age hardening response of the composites was studied and compared with the characteristics exhibited by the matrix alloy. Reinforcement addition was found to considerably affect the age hardening behavior. Detailed transmission electron microscopy and differential scanning calorimetry observations were made to understand the aging response of the composites. The low strain rate and high strain rate deformation behavior of the MMCs were determined utilizing low velocity transverse rupture tests and true armor-piercing steel projectiles, respectively. Increasing the volume fraction of B4C led to a decrease in flexural strength. The flexural strength vs. strain rate plots showed a slight increase in strength followed by a decrease for all samples. The mechanical performance of the composites and the unreinforced alloy were greatly improved by heat treatment. The MMCs were found to be inferior to monolithic ceramics when used as facing plates in armors.
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DeMarco, James P. Jr. "Mechanical characterization and numerical simulation of a light-weight aluminum A359 metal-matrix composite." Master's thesis, University of Central Florida, 2011. http://digital.library.ucf.edu/cdm/ref/collection/ETD/id/4933.
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Aluminum metal-matrix composites (MMCs) are well positioned to replace steel in numerous manufactured structural components, due to their high strength-to-weight and stiffness ratios. For example, research is currently being conducted in the use of such materials in the construction of tank entry doors, which are currently made of steel and are dangerously heavy for military personnel to lift and close. However, the manufacture of aluminum MMCs is inefficient in many cases due to the loss of material through edge cracking during the hot rolling process which is applied to reduce thick billets of as-cast material to usable sheets. In the current work, mechanical characterization and numerical modeling of as-cast aluminum A359-SiCsubscript p]-30% is employed to determine the properties of the composite and identify their dependence on strain rate and temperature conditions. Tensile and torsion tests were performed at a variety of strain rates and temperatures. Data obtained from tensile tests were used to calibrate the parameters of a material model for the composite. The material model was implemented in the ANSYS finite element software suite, and simulations were performed to test the ability of the model to capture the mechanical response of the composite under simulated tension and torsion tests. A temperature- and strain rate-dependent damage model extended the constitutive model to capture the dependence of material failure on testing or service conditions. Several trends in the mechanical response were identified through analysis of the dependence of experimentally-obtained material properties on temperature and strain rate. The numerical model was found to adequately capture strain rate and temperature dependence of the stress-strain curves in most cases.; Ductility modeling allowed prediction of stress and strain conditions which would lead to rupture, as well as identification of areas of a solid model which are most likely to fail under a given set of environmental and load conditions.ID: 030423478; System requirements: World Wide Web browser and PDF reader.; Mode of access: World Wide Web.; Thesis (M.S.M.E.)--University of Central Florida, 2011.; Includes bibliographical references (p. 113-118).
M.S.
Masters
Mechanical, Materials, and Aerospace Engineering
Engineering and Computer Science
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Buonanno, Mark Anthony 1963. "The effect of processing conditions and chemistry on the electrochemistry of graphite and aluminum metal matrix composites." Thesis, Massachusetts Institute of Technology, 1992. http://hdl.handle.net/1721.1/13232.
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Thesis (Ph. D.)--Massachusetts Institute of Technology, Dept. of Materials Science and Engineering, 1992.Vita.
Includes bibliographical references (leaves 176-185).
by Mark Anthony Buonanno.
Ph.D.
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Changizi, Ahmad. "Production And Properties Of In-situ Aluminum Titanum Diboride Composites Formed By Slag-metal Reaction Method." Master's thesis, METU, 2005. http://etd.lib.metu.edu.tr/upload/12605914/index.pdf.
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In this study, production and properties of titanium diboride particle reinforced aluminum matrix composite were investigated. TiB2 particles form in-situ through the reaction of TiO2 and H3BO3 and Na3AlF6 in aluminum melt. The results showed that the in-situ TiB2 particles formed were spherical in shape and had an average diameter of 1mm .Moreover, the distribution of TiB2 particles in the matrix were uniform. The ultimate tensile strength, yield strength, flexural stress and hardness were found to while reduction in area and elongation were found to decrease with increase in reinforcement content in the matrix.
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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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Bakshi, Srinivasa R. "Plasma And Cold Sprayed Aluminum Carbon Nanotube Composites: Quantification Of Nanotube Distribution And Multi-Scale Mechanical Properties." FIU Digital Commons, 2009. http://digitalcommons.fiu.edu/etd/97.
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Carbon nanotubes (CNT) could serve as potential reinforcement for metal matrix composites for improved mechanical properties. However dispersion of carbon nanotubes (CNT) in the matrix has been a longstanding problem, since they tend to form clusters to minimize their surface area. The aim of this study was to use plasma and cold spraying techniques to synthesize CNT reinforced aluminum composite with improved dispersion and to quantify the degree of CNT dispersion as it influences the mechanical properties. Novel method of spray drying was used to disperse CNTs in Al-12 wt.% Si pre-alloyed powder, which was used as feedstock for plasma and cold spraying. A new method for quantification of CNT distribution was developed. Two parameters for CNT dispersion quantification, namely Dispersion parameter (DP) and Clustering Parameter (CP) have been proposed based on the image analysis and distance between the centers of CNTs. Nanomechanical properties were correlated with the dispersion of CNTs in the microstructure. Coating microstructure evolution has been discussed in terms of splat formation, deformation and damage of CNTs and CNT/matrix interface. Effect of Si and CNT content on the reaction at CNT/matrix interface was thermodynamically and kinetically studied. A pseudo phase diagram was computed which predicts the interfacial carbide for reaction between CNT and Al-Si alloy at processing temperature. Kinetic aspects showed that Al4C3 forms with Al-12 wt.% Si alloy while SiC forms with Al-23wt.% Si alloy. Mechanical properties at nano, micro and macro-scale were evaluated using nanoindentation and nanoscratch, microindentation and bulk tensile testing respectively. Nano and micro-scale mechanical properties (elastic modulus, hardness and yield strength) displayed improvement whereas macro-scale mechanical properties were poor. The inversion of the mechanical properties at different scale length was attributed to the porosity, CNT clustering, CNT-splat adhesion and Al4C3 formation at the CNT/matrix interface. The Dispersion parameter (DP) was more sensitive than Clustering parameter (CP) in measuring degree of CNT distribution in the matrix.
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Hajiha, Reza. "A Novel Method in Additive Manufacturing of Titanium Matrix Composites with Ceramic Reinforcement by Thermal Decomposition of Aluminum Sulfate." Thesis, California State University, Long Beach, 2018. http://pqdtopen.proquest.com/#viewpdf?dispub=10838545.
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Metal matrix composites (MMCs) microstructure consists of a metallic alloy and a particular reinforcing component, ceramic in the case of this research. They are of high interest due to their high temperature strength, improved thermal stability, improved friction and wear resistant. Defining a low-cost additive manufacturing process that can fabricate high-quality MMC parts will combine the benefit of additive manufacturing and MMC together, which is highly desirable in today’s manufacturing.
This research introduces a novel method to fabricate MMC by introduction of uniformly distributed and dispersed ultra-fine ceramic particles within a metal substrate to form metal-ceramic composite during bulk sintering and to further develop three dimensional printing for fabrication of MMC structures reinforced by ceramic particles. This novel process is capable to fabricate metal-ceramic composite structures with a lower cost and shorter lead time in manufacturing compared to other existing additive manufacturing processes.
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Perron, Christophe. "Définition et mise en oeuvre d'un matériau composite à matrice métallique pour les packagings d'électronique embarquée." Thesis, Bordeaux, 2017. http://www.theses.fr/2017BORD0646/document.
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Les packagings d’électronique embarquée sont actuellement en alliages d’aluminium. A partir d’une étude de sélection des matériaux, complétée par une simulation numérique thermique,nous avons démontré qu’un matériau composite constitué d’une matrice aluminium et de fibres de carbone à forte conductivité thermique, représente un fort potentiel de gain de masse sur ces équipements. Cependant, le couplage de ces deux matériaux génère des problèmes d’élaboration en raison d’incompatibilités fortes parmi lesquelles un mouillage très faible du carbone par l’aluminium liquide et une réactivité chimique élevée qui conduit à la formation de carbures d’aluminium préjudiciables pour le matériau final. Deux voies d’élaboration distinctes ont été envisagées : Une voie liquide où l’utilisation d’un agent de mouillage (un sel fluoré) a permis d’obtenir la montée par capillarité du métal dans des mèches de fibres. Une voie solide basée sur une technique originale d’empilements de feuillets d’aluminium et de fibres de carbone avec le procédé de Spark Plasma Sintering (SPS). .La seconde technique s’est révélée prometteuse en permettant d’obtenir des échantillons multicouches sans porosités, un endommagement très limité des fibres et une architecture contrôlée.Notre étude a montré que la formation de carbures d’aluminium est limitée. De plus, une meilleure compréhension du SPS ou l’application d’un revêtement sur les fibres devraient permettre d’éviter la formation de ces carbures. Les tentatives de caractérisations mécanique et thermique effectuées sur ces échantillons donnent un premier aperçu de l’efficacité du renforcement de l’aluminium par les fibres de carboneEmbedded electronic packagings are currently made of aluminum. A first study – basedupon a material selection method completed by numerical analysis – showed that a metal matrixcomposite made of aluminum and highly thermal conductive continuous carbon fibers represents ahigh potential upon weight savings for those equipments. Though, coupling these componentsrepresents numerous challenges due to their incompatibility such as a really low wetting of carbonliquidaluminum system and its unavoidable chemical reactivity that leads to the formation ofaluminum carbides that are harmful for the final material. Two manufacturing routes were considered: A liquid route using a wetting agent (fluorinated salts) led the metal to rise alongcarbon fibers by capillarity. A solid route based upon a novel technique of aluminum foils and carbon fibersstacking using the Spark Plasma Sintering (SPS) process.This second technique revealed to be very promising and allowed to obtain multilayer samples with noporosities, highly limited fiber damages and controlled composite architecture. Our study shows thataluminum carbides formation is limited. Moreover, a deeper comprehension of SPS process or thedeposit of fiber coatings would prevent this carbide formation. Attempts of mechanical and thermalcharacterization led upon such samples give a first overview of the efficiency of the aluminumreinforcement by carbon fibers
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Jagannathan, Vijay. "The influence of interphase structure on the kinetics of oxygen reduction on graphite used in aluminum-graphite metal matrix composites /." The Ohio State University, 1988. http://rave.ohiolink.edu/etdc/view?acc_num=osu1487590702992934.
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Ma, Yu. "Effects of TiB2 nanoparticles on the interfacial precipitation and mechanical properties of Al-Zn-Mg-Cu matrix composites." Thesis, Université Paris-Saclay (ComUE), 2019. http://www.theses.fr/2019SACLS252.
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L’influence des renforts nanoparticules de TiB2 (6 wt.%) sur la précipitation interfaciale de la phase (Zn1.5Cu0.5)Mg, la résistance à la traction et la fissuration sous chargement de fatigue (fatigue crack growth-FCG) des composites à matrice de Al-Zn-Mg-Cu ont été étudiées. Des échantillons de composites ont été obtenus par réaction in-situ pendant le moulage suivi d’un FSP (friction stir processing) et une extrusion à chaud. Seuls les échantillons moulés et extrudés ont été utilisés pour étude de FCG à cause de la limitation de la taille après FSP. Des observations au microscope électronique à balayage (SEM), avec la diffraction des électrons rétrodiffusés (SEM/EBSD) et au microscope électronique en transmission à haute résolution (HRSTEM) ont été réalisées pour caractériser la microstructure.Des échantillons présentent une structure des grains équi-axiaux et des nanoparticules de TiB2 sont distribuées de façon homogène dans la matrice. En état de solution solide, l’interface TiB2/Al est de nature semi-cohérente et très propre. En état de vieillissementou ou sur vieillissement, la précipitation interfacaile hétérogène de la phase (Zn1.5Cu0.5)Mg a été observée. La cinétique de la précipitation interfaciale a été discutée. Les interfaces entre Al/(Zn1.5Cu0.5)Mg/TiB2 sont quasi cohérentes et l’interface TiB2/Al a été renforcée grâce à la réduction de l’énergie de l’interface. Ce mécanisme de précipitation interfaciale peut expliquer l’effet de renforcement de l’interface contribuant simultanement l’augmentation de la résistance et de l’élongation des échatillons de composite.La majorité de nanoparticules TiB2 tentent de s’agglomérer le long des joints de grains dans des échantillons sans FSP. La vitesse de croissance de fissure a été augmentée à l’intérieur des grains avec un facteur d’intensité (ΔK) intermédiaire ou important à cause de l’affinement de grains. Cependant, la vitesse de croissance de fissure a été diminuée aux joints de grains avec (ΔK) faible ou intermédiaire à cause de la présence des clusters de TiB2 tandis que cette vitesse augmente avec (ΔK) important à cause de la coalescence des microporesThe influences of TiB2 reinforcement nanoparticles (6 wt.%) on the interfacial precipitation of (Zn1.5Cu0.5)Mg phase, the associated tensile and fatigue crack growth (FCG) properties of the Al-Zn-Mg-Cu matrix composites have been studied. The composite samples were produced by in-situ reaction during casting followed by friction stir processing (FSP) and hot extrusion, while only casted and extruded samples were used for evaluating FCG due to size limit of the nugget zone after FSP. Scanning electron microscopy (SEM), electron backscatter diffraction (EBSD) and high-resolution scanning transmission electron microscopy (HRSTEM) were employed for the microstructure characterization.The as-processed composite samples contain the fine equiaxed-grain structure, where TiB2 nanoparticles are homogenously distributed. At solid-solution state, the TiB2/Al interfaces are featured by the clean and semi-coherent nature. At the peak-aged and overaged states, the interface precipitate determined as (Zn1.5Cu0.5)Mg phase was formed, and the underlying heterogeneous interfacial precipitation kinetics was discussed. The Al/(Zn1.5Cu0.5)Mg/TiB2 multi-interfaces were revealed to be almost coherent, and the TiB2/Al interfaces were thus strengthened due to the greatly reduced coherency strains. This mechanism was proposed as precipitation assisted interface strengthening, which has contributed to the simultaneously enhanced tensile strength and uniform elongation of the as-processed composite.The majority of TiB2 nanoparticles tend to aggregate along grain boundaries (GBs) in the composite samples without FSP. The FCG rate is increased inside grains at intermediate and high stress intensity factor (ΔK) ranges due to the refined grain size. However, the FCG rate at the GBs is decreased at the low and intermediate ΔK ranges by fatigue crack deflection and trapping due to the presence of TiB2 clusters, while it increases at the high ΔK range due to microvoid coalescence
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Negroni, Matteo. "Studio e sviluppo di tecniche per la produzione di nanocompositi a matrice di alluminio." Master's thesis, Alma Mater Studiorum - Università di Bologna, 2013. http://amslaurea.unibo.it/4949/.
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Foundry aluminum alloys play a fundamental role in several industrial fields, as they are employed in the production of several components in a wide range of applications. Moreover, these alloys can be employed as matrix for the development of Metal Matrix Composites (MMC), whose reinforcing phases may have different composition, shape and dimension. Ceramic particle reinforced MMCs are particular interesting due to their isotropic properties and their high temperature resistance. For this kind of composites, usually, decreasing the size of the reinforcing phase leads to the increase of mechanical properties. For this reason, in the last 30 years, the research has developed micro-reinforced composites at first, characterized by low ductility, and more recently nano-reinforced ones (the so called metal matrix nanocomposite, MMNCs). The nanocomposites can be obtained through several production routes: they can be divided in in-situ techniques, where the reinforcing phase is generated during the composite production through appropriate chemical reactions, and ex situ techniques, where ceramic dispersoids are added to the matrix once already formed. The enhancement in mechanical properties of MMNCs is proved by several studies; nevertheless, it is necessary to address some issues related to each processing route, as the control of process parameters and the effort to obtain an effective dispersion of the nanoparticles in the matrix, which sometimes actually restrict the use of these materials at industrial level.
In this work of thesis, a feasibility study and implementation of production processes for Aluminum and AlSi7Mg based-MMNCs was conducted. The attention was focused on the in-situ process of gas bubbling, with the aim to obtain an aluminum oxide reinforcing phase, generated by the chemical reaction between the molten matrix and industrial dry air injected in the melt. Moreover, for what concerns the ex-situ techniques, stir casting process was studied and applied to introduce alumina nanoparticles in the same matrix alloys. The obtained samples were characterized through optical and electronic microscopy, then by micro-hardness tests, in order to evaluate possible improvements in mechanical properties of the materials.
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Bravo, Salazar Jaime Alejandro. "Estudo do processo de fabricação de compósitos AA6061 + TiCN por sinterização com fase líquida e caracterização do produto." [s.n.], 2007. http://repositorio.unicamp.br/jspui/handle/REPOSIP/263635.
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Orientadores: Maria Helena Robert, Elisa Maria Ruiz NavasTese (doutorado) - Universidade Estadual de Campinas, Faculdade de Engenharia Mecânica
Made available in DSpace on 2018-08-19T00:27:43Z (GMT). No. of bitstreams: 1 BravoSalazar_JaimeAlejandro_D.pdf: 9695376 bytes, checksum: d35ebfbcaf1dac8c6665392b7d784d23 (MD5) Previous issue date: 2007
Resumo: Este trabalho estuda o processo de fabricação de compósitos de matriz de alumínio AA6061 reforçado com TiCN por metalurgia do pó, envolvendo as etapas de mistura de pós, compactação uniaxial e sinterização com fase líquida. Para efeitos de comparação foram produzidos e caracterizados compactados da liga AA6061 sem adição de reforços. Foram investigados os parâmetros de processo: teores de reforço (5% e 10% massa), teor de aditivos Pb e Sn (0,1, 0,15, 0,2 e 0,4% massa), pressão de compactação (400, 600 e 800 MPa), tempos (15, 30, 45 e 60 min) e temperatura de sinterização (590, 600, 610 e 620 ºC). Em cada etapa do processo foram caracterizados os produtos (mistura de pós e compactados); o produto final obtido, após sinterização, foi caracterizado com relação à sua microestrutura, propriedades físicas (densificação e variação dimensional) e mecânicas (resistência à flexão e dureza). Os resultados obtidos mostraram uma grande eficiência do processo na obtenção de compósitos; a adição do teor de reforço de 5%TiCN foi eficiente na promoção de rupturas das camadas de óxidos do pó da liga de alumínio compactado à pressão de 400 MPa, auxiliando a sinterização por difusão da fase líquida formada a partir da fusão de Al+Mg2Si, melhorando a densificação e diminuindo a variação dimensional dos produtos sinterizados. Do ponto de vista metalúrgico, os materiais compósitos obtidos apresentaram microestruturas homogêneas, com uma boa distribuição dos reforços na matriz e relativa diminuição de poros. A adição de Pb e Sn promovem maior eficiência de ativação de mecanismos de sinterização; para compactados produzidos à pressão de 800 MPa, a adição de 0,1% desses elementos já apresentou significativa influência na sinterização. Com relação às propriedades mecânicas e físicas observou-se que a adição de TiCN aumentou quase no dobro de seus valores obtidos quando são comparados com a liga AA6061
Abstract: This work investigates the process of production of composites of the alloy AA6061 reinforced with TiCN particles, by powder metallurgy involving the steps: conventional mixture of powders, compaction by uniaxial cold pressing and sintering with formation of a liquid phase. For comparative analysis it was also produced sintered AA6061 without addition of reinforcements. The following processing parameters were studied: reinforcing particles content (5 and 10 wt%); content of trace elements Pb and Sn (0.1, 0.15, 0.2 0.4 wt%); compaction pressure (from 400, 600 and 800 MPa); time and temperature of sintering (15, 30, 45, 60 min and 590, 600, 610, 620 oC). In each step products were characterized (powder mixture and green compacts); the final sintered product was characterized related to microstructure, physical (densification and dimensional changes) and mechanical (hardness and bending strength) properties. Obtained results showed high efficiency of the applied process to produce reliable composite products; the addition of 5 wt% TiCN was efficient to promote fracture of the oxide layer in the aluminum particles surface during pressing. At sintering temperatures liquid phase is formed by Al+Mg2Si melting and is distributed among particles through the fractures of the oxide layer, improving the material densification and its mechanical properties. Microstructures obtained showed homogeneous distribution of TiCN and reduced porosity, whereas AA6061 alloy microstructure showed higher porosity. Addition of Pb and Sn promoted higher efficiency of sintering mechanisms in compacts submitted to high pressures, leading to enhanced physical and mechanical properties in those materials.
Doutorado
Materiais e Processos de Fabricação
Doutor em Engenharia Mecânica
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Ali, Fahad [Verfasser], Jürgen [Akademischer Betreuer] Eckert, and N. K. [Akademischer Betreuer] Mukhopadhyay. "Mechanical milling of Al-Cu-Fe quasicrystals and their Reinforcement in Aluminum matrix composites / Fahad Ali. Gutachter: Jürgen Eckert ; N.K. Mukhopadhyay. Betreuer: Jürgen Eckert." Dresden : Saechsische Landesbibliothek- Staats- und Universitaetsbibliothek Dresden, 2012. http://d-nb.info/1068442875/34.
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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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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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Li, Q. F. "Studies in the solidification behaviour of aluminium alloy/alumina metal matrix composites (MMC's)." Thesis, University of Liverpool, 1991. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.260364.
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Jen, Wen-Dar, and 鄭文達. "Electroplate copper in 7005/Al2O3 Aluminum Matrix Composites." Thesis, 1997. http://ndltd.ncl.edu.tw/handle/11279520180297114819.
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Chang, Chuan-Jen, and 張銓仁. "The Research of Machinability of Aluminum Matrix Composites." Thesis, 2010. http://ndltd.ncl.edu.tw/handle/84657450810579768952.
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碩士臺灣大學
機械工程學研究所
99
An experimental investigation on the end milling of aluminum based metal matrix composites with different percentage of Al2O3 particles was conducted in this study. The machinability in terms of tool wear, surface roughness, cutting force and chip morphology was studied under different cutting settings including dry cutting, wet cutting and minimum quantity lubrication with nano fluid and the water-based fluid. The results show that flank wear occurs in dry cutting of 10 wt.% Al2O3 aluminum metal matrix, It will cause serious built-up edge, but it can be reduced by using minimum quantity lubrication with nano. The nano particles can generate a solid lubricant layer between the tool face and chips. Hence chip sticking on tool face is reduced and the surface roughness is improved. The cutting of 15 wt.% Al2O3 aluminum metal matrix causes fewer built-up edge but more serious flank wear than that of 10 wt.% Al2O3 aluminum metal matrix. Using minimum quantity lubrication with nano fluid can improve tool life and surface roughness in cutting of 15 wt.% Al2O3 aluminum metal matrix. However, the effect is the same as that of wet cutting. Using the polycrystalline diamond tool can improve flank wear under dry cutting, but micro chipping will occur in wet cutting. It is effective in cutting 10 wt.% Al2O3 and 15 wt.% Al2O3 aluminum metal matrix composites with coated carbide tool by using MQL with nano fluid, but PCD tool is better in cutting 20 wt.% Al2O3 aluminum metal matrix composites under dry cutting condition.
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Ganguly, Partha. "High temperature deformation and failure in aluminum-alumina particulate metal matrix composites." Thesis, 1998. http://hdl.handle.net/2429/7778.
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This work was primarily concerned with investigating the role of the reinforcing
particles on plastic flow and fracture of metal matrix composites (MMCs) in the high
temperature, moderately high strain rate domain. Uniaxial tensile, uniaxial compressive,
and collar compressive tests were conducted on as-cast and extruded MMCs (the uniaxial
tests were also conducted on unreinforced AA6061), and the flow and fracture behavior
of the materials examined. The micro-failure characteristics were ascertained through
metallographic examination of the fractured samples - both perpendicular and parallel to
the fracture surface, and through numerical simulations of the collar compression test on
the as-cast MMC .
The reinforcing particles were found to enhance the flow stress and lower the
failure strain in these materials. The detrimental effect of the particles on failure strain
was higher for the as-cast M M C - and this was deemed to be due to the presence of
particle rich clusters in its microstructure. In both the extruded and as-cast MMCs,
particle cracking and interfacial decohesion were the primary void nucleation
mechanisms. The dominance of one mechanism over another was found to be
temperature dependent - the former dominating at lower and the latter at higher
temperatures. The MMC ductility peaked in the mid-temperature region, where the
occurrence of the two mechanisms was comparable.
50
Ruen, Jen Kuo, and 袁鎮國. "the study of electroless copper coated alumina particles reinforced aluminum matrix composites." Thesis, 1994. http://ndltd.ncl.edu.tw/handle/22243950714601536562.
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