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Yuan, Fei (Fred) Materials Science & Engineering Faculty of Science UNSW. "Properties of titanium matrix composites reinforced with titanium boride powders." Awarded by:University of New South Wales. Materials Science & Engineering, 2007. http://handle.unsw.edu.au/1959.4/40750.
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Metal matrix composites can produce mechanical and physical properties better than those of the monolithic metal. Titanium alloys are widely used matrix materials as they can offer outstanding specific strength, corrosion resistance and other advantages over its competitors, such as aluminium, magnesium and stainless steel. In past decades, titanium matrix composites served in broad areas, including aerospace, military, automobile and biomedical industries. In this project, a revised powder metallurgy method, which contains cold isostatic pressing and hot isostatic pressing, was adopted to refine the microstructure of monolithic titanium. It was also used to manufacture titanium matrix composites. TiH2 powder was selected as the starting material to form Ti matrix and the reinforcements were sub-micron and nano-metric TiB particles. Mechanical properties and microstructure of commercial titanium composites exhaust valves from Toyota Motor Corporation have been studied as the reference of properties of titanium composites manufactured in this project. It has been shown that tensile strength and hardness of exhaust valves increase about 30% than those of similar matrix titanium alloys. Examination on powder starting materials of this project was also carried out, especially the dehydrogenation process shown in the DSC result. Mechanical properties and microstructures of titanium matrix composites samples in this project, as related to the process parameter, have also been investigated. The density of these samples reached 96% of theoretical one but cracks were found through out the samples after sintering. Fast heating rates during the processing was suspected to have caused the crack formation, since the hydrogen release was too fast during dehydrogenation. Hardness testing of sintered samples was carried out and the value was comparable and even better than that of commercial exhaust valves and titanium composites in literature. Microstructure study shows that the size of reinforcements increased and the size of grains decreased as the increasing amount of TiB reinforcements. And this condition also resulted in the increasing amount of the acicular alpha structure.
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Tesha, Joseph Valerian. "Processing of SiC/titanium metal matrix composites." Thesis, Cranfield University, 1993. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.358232.
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Pollard, Sarah Louise. "Processing and properties of titanium metal matrix composites." Thesis, University of Birmingham, 2011. http://etheses.bham.ac.uk//id/eprint/7605/.
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This thesis addresses aspects of the development of both processing methods and the assessment of the mechanical properties of titanium metal matrix composites in order for the material to be introduced with confidence into aero-engine applications. Assessment of the SM1140+ fibre has been carried out and compared with the SCS-6 and Trimarc fibres in order to gain an appreciation of the performance of these fibres in relation to each other to aid fibre selection and to aid further development of composite components. The SM1140+ fibre is found to fail almost always from the core and is consistent with a statistical distribution that can be modelled by a unimodal Weibull approach. The development of the SM2156 fibre was made in an effort to produce both a UK source and a lower cost source of fibre. Mechanical testing of fibre in both as-received and composite form revealed a decrease in strength when compared with results for the virgin, uncoated fibre and by deduction from SCS-6 composite mechanical behaviour. The deterioration of fibre properties appears to be caused by the rough surface of the SiC fibre causing a ‘keying’ effect that inhibits interfacial sliding. The high rate sputtering deposition process has been developed in order to obtain an alternative, lower cost method of producing matrix coated fibre. Testing of the MCF showed a mild deterioration of fibre strength during processing (due to fibre spooling), but still demonstrated the composite shows potential for production given further development.
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Jong, Edwin Nyon Tchan. "Particulate-reinforced metal matrix composites based on titanium alloys." Thesis, Imperial College London, 1992. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.261498.
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Dear, Matthew Nicholas. "Fatigue in SiC fibre reinforced titanium metal matrix composites." Thesis, University of Birmingham, 2016. http://etheses.bham.ac.uk//id/eprint/6603/.
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The fatigue and interfacial characteristics of a unidirectional, SiC (SCS 6), fibre reinforced Ti 6Al 4V metal matrix composite have been investigated using a series of fatigue crack propagation, total life, and interfacial characterisation techniques. A room temperature crack arrest to catastrophic failure (CA/CF) transition was quantified using the initial stress intensity factor range ΔKapp. This transition occurred between 21 and 18 MPa√m in the three point bend geometry, and was found to be dependent on volume fraction of intact fibres bridging the crack. Increasing the test temperature to 300˚C had different effects on the resistance to fatigue crack growth depending on crack opening displacements and test piece stiffness. Total life fatigue tests revealed that the dominant failure mechanism was matrix fatigue cracking and fibre bridging. The extent of fatigue crack growth and fibre bridging was dependant on the applied stress and test temperature. The introduction of a dwell period at maximum load resulted in a small reduction in the total fatigue life. Post fatigue fibre push out tests identified that fatigue caused a reduction of interfacial properties below the as received levels. This reduction of interfacial properties was dependent on fatigue test temperature and initial loading conditions.
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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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Marte, Judson Sloane. "High temperature flow behavior of titanium aluminide intermetallic matrix composites /." This resource online, 1996. http://scholar.lib.vt.edu/theses/available/etd-11012008-063708/.
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Patil, Amit k. "ADVANCED PROCESSING OF NICKEL-TITANIUM-GRAPHITE BASED METAL MATRIX COMPOSITES." Cleveland State University / OhioLINK, 2019. http://rave.ohiolink.edu/etdc/view?acc_num=csu1560298763233401.
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Marte, Judson Sloan. "High temperature flow behavior of titanium aluminide intermetallic matrix composites." Thesis, Virginia Tech, 1996. http://hdl.handle.net/10919/45422.
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Al₃Ti, Al₅CuTi₂, and Al₆₆Mn₁₁Ti₂₃, intermetallic matrices reinforced with 30, 40, and 50 volume % TiB, have been produced by XD™ processing and densified into bulk form by powder metallurgy techniques. The compressive flow behavior of the Al₃Ti and Al₅CuTi₂, composites have been evaluated at temperatures ranging from 1000°C to 1200°C and strain rates of 0.0001 and 0.001 sec⁻¹. The results have been analyzed by a correlation to the resulting microstructure, especially with regards to the intermetallic matrix composition, TiB₂ size, and interparticle spacing. The results of these analyses are applied to a constitutive equation based upon the flow stress equation.
It has been shown that at in this temperature regime, all deformation occurs within the intermetallic matrix. This is substantiated by the lack of TiB₂-dependent behavior with variations in volume percentage of reinforcement. In all cases, the composites are readily deformed at relatively low loads. The average strain-rate sensitivity values were 0.349 for the Al₃Ti-based composites, and 0.247 for the Al₅CuTi₂, variants. The average activation energies were calculated to be 485 kJ/mol and 920 kJ/mol for the Al₃Ti-and Al₅CuTi₂-matrices, respectively. The structure constant was calculated based upon these values. The Zener-Hollomon parameter was used to plot the flow stress along lines of constant temperature and strain rate, and serves as one type of constitutive equation. In addition, the flow stress was evaluated as a function of the strain rate and temperature. These models were found to provide adequate correlation to the measured flow behavior.Master of Science
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Baker, Adam M. "Interfacial and processing studies in Ti/SiC metal matrix composites." Thesis, University of Oxford, 1998. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.301852.
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Jin, Ohchang. "Damage accumulation and life prediction of titanium matrix composites subjected to elevated temperatures." Thesis, Georgia Institute of Technology, 1999. http://hdl.handle.net/1853/19542.
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Zamperini, Silvia. "Effects of cyclic loading on fibre reinforced titanium metal matrix composites." Thesis, University of Birmingham, 2002. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.289709.
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Kieschke, Robert Richard. "The interface region in titanium reinforced with silicon carbide monofilaments." Thesis, University of Cambridge, 1990. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.335165.
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Craft, Jason Scott. "Evaluation of advanced titanium matrix composites for 3rd generation reusable launch vehicles." Thesis, Georgia Institute of Technology, 2003. http://hdl.handle.net/1853/17644.
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Mogonye, Jon-Erik. "Solid Lubrication Mechanisms in Laser Deposited Nickel-titanium-carbon Metal Matrix Composites." Thesis, University of North Texas, 2012. https://digital.library.unt.edu/ark:/67531/metadc271864/.
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A Ni/TiC/C metal matrix composite (MMC) has been processed using the laser engineered net shaping (LENS) process from commercially available powders with a Ni-3Ti-20C (atomic %) composition. This processing route produces the in-situ formation of homogeneously distributed eutectic and primary titanium carbide and graphite precipitates throughout the Ni matrix. The composite exhibits promising tribological properties when tested in dry sliding conditions with a low steady state coefficient of friction (CoF) of ~0.1 and lower wear rates in comparison to LENS deposited pure Ni. The as deposited and tribologically worn composite has been characterized using Auger electron spectroscopy, scanning electron microscopy (SEM), X-ray diffraction, high resolution transmission electron microscopy (HRTEM) with energy dispersive spectroscopy (EDS), dual beam focused ion beam SEM (FIB/SEM) serial sectioning and Vickers micro-hardness testing. The evolution of subsurface stress states and precipitate motion during repeated sliding contact has been investigated using finite element analysis (FEA). The results of FIB/SEM serial sectioning, HRTEM, and Auger electron spectroscopy in conjunction with FEA simulations reveal that the improved tribological behavior is due to the in-situ formation of a low interfacial shear strength amorphous carbon tribofilm that is extruded to the surface via refined Ni grain boundaries.
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Sandhu, Suki. "Process-microstructure studies in TiAl/SiCâ†f composites." Thesis, University of Surrey, 1998. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.267847.
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Adoba, Anita Elameyi. "The development and characterisation of functionally graded titanium matrix composites with particular bioactive reinforcement." Thesis, University of London, 2002. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.271626.
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Zhao, Fei. "Study on mechanical properties of the in situ TiB/TiC reinforced titanium matrix composites." Troyes, 2010. http://www.theses.fr/2010TROY0030.
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Ces travaux de recherche ont pour objectif d’étudier les effets des renforts TiB et TiC dans les composites à matrice de titane sur les propriétés mécaniques, par analyse et caractérisation expérimentale et simulation numérique. Le comportement de traction, de frottement et de fatigue d'une série de composites renforcés par in situ TiB/TiC a été mis en évidence. La méthode des éléments finis permet également de simuler les effets des renforts. Les résultats obtenus montrent que les TiB/TiC peuvent jouer un rôle important de renforcement lors de sollicitations complexes. Les propriétés des composites (module élastique et de cisaillement) et la rigidité de ces matériaux dépendent du type, de la quantité, de la forme et de la distribution des renforts. Les renforts peuvent empêcher la propagation des fissures dans le cas statique. En dynamique, les renforts TiB réduisent la résistance à la fatigue des composites lorsque la sollicitation est importante, mais peuvent augmenter cette résistance lorsque la sollicitation est faible; par contre les renforts de TiC peuvent améliorer la résistance à la fatigue des composites. Dans la pratique, il faut aussi tenir compte des conditions de mise en forme et d’application des composites. Le contenu des renforts devrait être déterminé en tenant compte du coût de fabrication, de sorte que nous puissions optimiser les besoins d’application réelle, mais également de réduire les coûtsThe aim of this research is to study the effects of reinforcements TiB and TiC materials by experimental analyzing structures and mechanical testing of properties of in situ synthesize TiB/TiC reinforced titanium matrix composites. The tensile, friction and fatigue properties of in situ TiB/TiC reinforced composites structures were tested. Finite element analysis was also used to simulate the effect of the reinforcements. The results show that the reinforcements can play an important role in the composites properties. The elastic modulus and shear modulus have some relation with the type, the quantity, the shape and the distribution of the reinforcements in the composite materials. Some formulas about the modulus of the composites are suggested by modelling the composite behaviours with numerical method. The reinforcements can prevent the crack initiation and propagation in static load. For the fatigue properties, the reinforcement TiB reduces the fatigue life of the composites under high level of load, but increases it in low load conditions, while TiC reinforcements can improve the fatigue strength of the composites. So in practice, the applying conditions of the composites should be considered. The contents of the reinforcements should be determined by taking account of the manufacturing costs, so that we can to optimize the practical needs and to but reduce the costs
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Reeves, Andrew James. "The effect of interfacial reaction on the properties of titanium-matrix composites reinforced with SiC and TiB₂ particulate." Thesis, University of Cambridge, 1992. https://www.repository.cam.ac.uk/handle/1810/251912.
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Osborne, Deborah J. "Experimental and computational study of interphase properties and mechanics in titanium metal matrix composites at elevated temperatures /." View online ; access limited to URI, 2007. http://0-digitalcommons.uri.edu.helin.uri.edu/dissertations/AAI3277003.
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Lobley, Christopher Marcus. "Tape casting as a novel processing route for silicon carbide fibre-reinforced titanium metal matrix composites." Thesis, Queen Mary, University of London, 1999. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.298249.
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Borkar, Tushar Murlidhar. "Processing and Characterization of Nickel-Carbon Base Metal Matrix Composites." Thesis, University of North Texas, 2014. https://digital.library.unt.edu/ark:/67531/metadc500026/.
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Carbon nanotubes (CNTs) and graphene nanoplatelets (GNPs) are attractive reinforcements for lightweight and high strength metal matrix composites due to their excellent mechanical and physical properties. The present work is an attempt towards investigating the effect of CNT and GNP reinforcements on the mechanical properties of nickel matrix composites. The CNT/Ni (dry milled) nanocomposites exhibiting a tensile yield strength of 350 MPa (about two times that of SPS processed monolithic nickel ~ 160 MPa) and an elongation to failure ~ 30%. In contrast, CNT/Ni (molecular level mixed) exhibited substantially higher tensile yield strength (~ 690 MPa) but limited ductility with an elongation to failure ~ 8%. The Ni-1vol%GNP (dry milled) nanocomposite exhibited the best balance of properties in terms of strength and ductility. The enhancement in the tensile strength (i.e. 370 MPa) and substantial ductility (~40%) of Ni-1vol%GNP nanocomposites was achieved due to the combined effects of grain refinement, homogeneous dispersion of GNPs in the nickel matrix, and well-bonded Ni-GNP interface, which effectively transfers stress across metal-GNP interface during tensile deformation. A second emphasis of this work was on the detailed 3D microstructural characterization of a new class of Ni-Ti-C based metal matrix composites, developed using the laser engineered net shaping (LENSTM) process. These composites consist of an in situ formed and homogeneously distributed titanium carbide (TiC) as well as graphite phase reinforcing the nickel matrix. 3D microstructure helps in determining true morphology and spatial distribution of TiC and graphite phase as well as the phase evolution sequence. These Ni-TiC-C composites exhibit excellent tribological properties (low COF), while maintaining a relatively high hardness.
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Angle, Jonathan Willis. "Microstructural Engineering of Titanium-Cellulose Nanocrystals Alloys via Mechanical Alloying and Powder Processing." Thesis, Virginia Tech, 2018. http://hdl.handle.net/10919/87473.
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Titanium been used industrially for nearly a century. Ever since it was first reduced to its elemental form, concerted efforts have been made to improve the material and to reduce the cost of production. In this thesis, titanium is mechanically alloyed with cellulose nanocrystals followed by powder consolidation and sintering to form a solid titanium metal matrix composite. Cellulose nanocrystals (CNCs) were chosen as the particle reinforcement as they are a widely abundant and natural material. Additionally, the nanocrystals can be derived from waste materials such as pistachio shells. This offers a unique advantage to act as a green process to enhance the mechanical properties of the titanium as well as to reduce to cost of production.
Vibrational milling using a SPEX 8000M mill was used to mechanically alloy titanium powder with varying concentrations of CNCs. Additionally, the milling time was varied. This process showed that varying the concentrations of CNCs between 0.5% - 2% by weight did not noticeably alter the microstructural or mechanical properties of the materials. Conversely, changing the milling time from 0.5 hours to 5 hours proved to greatly alter the microstructural and mechanical properties of the titanium matrix metal composites. Further increasing the milling time to 10 and 25 hours caused the materials to become exceedingly brittle thus, the majority of experiments focused on samples milled between 0.5 hours and 5 hours. The hardness values for the Ti-1%CNC materials increased from 325-450-600-800 for the samples milled for 0.5, 1, 2, and 5 hours respectively. The other concentrations used were found to yield similar values and trends. SEM micrographs showed that small precipitates had formed within the grains except materials milled at 5 hours, which showed the production of very coarse particles at the grain boundaries.
Similarly, an attrition mill was used to mechanically alloy titanium with varying CNC concentrations. Milling time was also varied. The powders were consolidated, sintered and characterized. It was found that increasing CNC content at low milling times caused a reduction in hardness. The X-ray diffractograms also showed a trend in that the diffraction patterns shifted to the lower angle with increasing CNC concentration, thereby suggesting that the increase in CNC content facilitated the removal of oxygen atoms housed within the interstitial sites. The oxygen was observed to diffuse and precipitate platelet titanium dioxide particles. These particles were found to be located within the titanium grains and coarsened with milling time. Generally, increasing the milling time to 15 hours was found precipitate particles at the grain boundaries as well as to excessively dissolve oxygen into the titanium lattice leading to embrittlement. The materials milled for 5 hours showed the best increase in strength while maintaining good ductility.Master of Science
Titanium has only been used industrially since the early 1940’s thanks in large to the modern advances to reduce titanium ore to its elemental state. Titanium gained much interest as a structural material because of its corrosion resistance and its exceptional strength for a lightweight metal, making the material ideal for medical and aerospace applications. Pure titanium was found to be soft and had poor wear resistance, therefore, efforts were made to create titanium alloys which mitigated these weaknesses. Often titanium is alloyed with costly and toxic elements to enhance its strength properties, making it dangerous to use in the medical field. One way to enhance the strength properties of titanium without the addition of these harmful alloying elements is to create a titanium composite by adding strong inert particles to a titanium matrix. One method to create titanium metal matrix composites is to violently mix titanium powder with the reinforcement material, through a process called mechanically alloying. Following the mixing process the powder is then compacted and heated to form a solid part through a process called sintering. While these powder processing methods are known and viable for forming titanium metal matrix composites, some of the reinforcement materials can be expensive. In this thesis, cellulose nanocrystals (CNCs) will be added as reinforcement to titanium by means of two mechanical alloying processes, vibratory milling (shaking) and attrition milling (stirring). CNCs can be derived from plant matter which is widely abundant and inexpensive. The viability of CNCs to be used as a reinforcement material, as well as the mechanical alloying processes were investigated to determine the effect on the titanium strength properties. The powder processing steps were found to cause the CNCs to react with the surrounding titanium matrix which caused beneficial oxides to form as the reinforcement materials. In general, it was found that vibratory milling caused the final titanium metal matrix composite to be hard and brittle. Attrition milling was found to be more favorable as some materials were observed to be strong yet ductile.
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Friend, Gareth William. "The effect of defects on the mechanical properties of fibre reinforced titanium metal matrix composites under fatigue loading." Thesis, University of Birmingham, 2014. http://etheses.bham.ac.uk//id/eprint/5438/.
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Applications for titanium metal matrix composites (TiMMCs) are currently being developed by Rolls-Royce plc in gas turbine engine components. With any component manufacturing process there is a probability of defects, as much of the work on TiMMCs to date has been laboratory scale there is as yet no study that looks specifically at the defects that can arise in full scale components. This work set out to investigate the influence of a selection of defects on the fatigue properties of titanium diffusion bonds – an integral joint type in TiMMC components – using conditions derived from TiMMC component stress analysis. The study found that cladding material microstructure and texture greatly affected the fatigue life of the bond. This was characterised by a new technique called Spatially Resolved Acoustic Spectroscopy (SRAS). Airborne debris and residual degreasing agent staining were found to be contaminants the most detrimental to fatigue life and methods of modifying the manufacturing process have been suggested to eliminate them. A number of other methods have been discussed for reducing the sensitivity of the TiMMC components to defects of this type through the control of residual stresses microstructure and texture.
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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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Hill, Davion M. "Microstructure and mechanical properties of titanium alloys reinforced with titanium boride." Columbus, Ohio : Ohio State University, 2006. http://rave.ohiolink.edu/etdc/view?acc%5Fnum=osu1150402807.
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Pouzet, Sébastien. "Fabrication additive de composites à matrice titane par fusion laser de poudre projetée." Thesis, Paris, ENSAM, 2015. http://www.theses.fr/2015ENAM0051/document.
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Les composites à matrice titane (CMTi) sont des matériaux attractifs pour des applications aéronautiques, en raison de leurs performances mécaniques à haute température et de leur faible densité. La difficulté d’usiner ce type de matériaux rend les procédés de fabrication additive intéressants pour la fabrication de pièces complexes en trois dimensions. Cette étude porte sur l'élaboration de composites à matrice titane par le procédé de fabrication additive par fusion laser de poudre projetée. Dans un premier temps, différents types de poudres- renfort et de préparations de poudre ont été utilisés pour faciliter la mise en œuvre du procédé additif, dans le but d’obtenir des microstructures homogènes. Dans un second temps, l’étude s’est concentrée sur le mélange Ti-6Al-4V / B4C formant des renforts TiB et TiC par voie in-situ dans une matrice de Ti-6Al-4V. Les mécanismes de formation des microstructures obtenues ont pu être expliqués puis une étude des propriétés mécaniques (dureté, module d’Young et comportement sous une sollicitation en traction à chaud et à l’ambiante) a été réalisée afin d’évaluer l’effet du renforcement sur les propriétés mécaniques du matériau. Parmi les résultats importants ce cette étude, la présence de taux de carbone élevés en solution solide dans la matrice de titane a été évoqué comme étant le facteur prédominant dans l'augmentation des propriétés mécaniques avec le taux de B4CTitanium matrix composites are attractive materials for aeronautical applications, mainly because of their superior mechanical resistance at elevated temperature, combined with a low density. The critical machinability of such composites makes additive manufacturing processes particularly adapted for building complex 3D shapes. This study has been focused on the Direct Metal Deposition (DMD) of Metal matrix composites. In a first step, various powders and powder blends have been carried out in order to facilitate the DMD process and to obtain homogeneous microstructures. Following this, Ti-6Al-4V / B4C powder blends, allowing to obtain TiB + TiC particles distributed in the Ti matrix were more specifically considered. Metallurgical mechanisms involved in the formation of microstructures were identified prior to an investigation on mechanical properties at ambient and elevated temperature for various DMD process conditions and particle concentrations. Among the most interesting results of this study, the influence of a high carbon content solubilized in the Ti-matrix was considered as a dominant factor to explain the evolution of mechanical properties with increased amounts of reinforcements
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Motsi, Glenda Tsholofelo. "Spark plasma sintering de composites base titane renforcés par des carbures pour applications en tribocorrosion." Thesis, Toulouse 3, 2019. http://www.theses.fr/2019TOU30309.
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La faible résistance à l'usure du titane et de ses alliages limite leur application dans laquelle l'effet combiné de l'usure et de la corrosion peut être rencontré. À cet égard, l'ajout de phases céramiques sous forme de whiskers (TiB) ou de particules (TiB2 et TiC) dans une matrice à base de titane pour former des composites avancés à matrice de titane (TMC), peut aider à réduire les pertes de matériau et à prolonger la durée de vie. Dans cette étude, les composites de titane à base de TiB2, TiB et TiC ont été produits par Spark Plasma Sintering (SPS) réactif de titane pur commercial (CP-Ti) et de poudres B4C de différentes tailles de particules. On s'est rendu compte qu'à une température de consigne de 800°C, la réaction avait commencé en raison des avantages du courant pulsé dans le SPS. L'analyse SEM / FIB / TEM sur le matériau fritté à 800°C a montré une phase grise continue, constituée d'amas de particules de B4C partiellement réagies ségrégés aux joints des grains de la matrice Ti. À 1100°C, les réactifs ont complètement réagi et se sont transformés en clusters de divers composés riches en B et C (Ti-B et Ti-C). L'homogénéisation de la microstructure a été obtenue à des temps de séjour de 0 à 30 min pour éliminer les amas formés. Le comportement en corrosion et en tribocorrosion du CP-Ti et des TMC a été étudié dans des solutions 3,5% molaire de NaCl. Les résultats ont montré qu'une quantité croissante des phases de renforcement à 5% en poids réduisait la sensibilité à la corrosion et à la tribocorrosion des TMC frittés à 1100°C, car les valeurs de potentiel en circuit ouvert étaient positivement décalées pour Ti5wt% B4C. De graves dommages à la surface avec des rainures profondes dans CP-Ti ont été observés dans les pistes usées indiquant une usure adhésive. Aucun retrait des phases de renforcement TiB et TiC n'a été observé pour Ti5wt% B4C, en raison de la forte force de liaison interfaciale avec la matrice TiThe poor wear resistance of titanium and its alloys limit their application in which the combined effect of wear and corrosion may be encountered. In this regard, addition of ceramic phases in the form of whiskers (TiB) or particles (TiB2 and TiC) in titanium based matrix to form advanced titanium matrix composites (TMCs), can aid reduce material loss and prolong the service life. In this study TiB2, TiB and TiC based titanium composites were produced by reactive Spark Plasma Sintering (SPS) of commercial pure titanium (CP-Ti) and B4C powders of varying particles sizes. It was realized that at 800°C set-point temperature the reaction had initiated due to the benefits of pulsed current in the SPS. SEM/FIB/TEM analysis on the material sintered at 800°C showed a continuous grey phase, constituted of clusters of partially reacted B4C particles segregated at Ti matrix grain boundaries. While at 1100°C, the reactants completely reacted and transformed into clusters of various compounds high in B and C (Ti-B and Ti-C). Microstructure homogenization was achieved at dwell times of 0-30 min to remove the formed clusters. Corrosion and tribocorrosion behaviour of CP-Ti and TMCs was investigated in solutions 3.5% molar of NaCl. The results showed that increasing amount of the reinforcing phases to 5wt% reduced the corrosion and tribocorrosion susceptibility of the TMCs sintered at 1100°C, as the open circuit potential values were positively shifted for Ti5wt%B4C. Severe surface damage with deep grooves in CP-Ti was observed in worn tracks indicating adhesive wear. No pulling out of TiB and TiC reinforcing phases was observed for Ti5wt%B4C, due to the strong interfacial bond strength with the Ti matrix
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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.
Full textAbstract:
Orientadores: Maria Helena Robert, Elisa Maria Ruiz NavasTese (doutorado) - Universidade Estadual de Campinas, Faculdade de Engenharia Mecânica
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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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Galdino, André Gustavo de Sousa. "Produção e caracterização de arcabouços porosos de compósitos hidroxiapatita-titânia (HA-TiO2) para uso em engenharia tecidual óssea." [s.n.], 2011. http://repositorio.unicamp.br/jspui/handle/REPOSIP/263456.
Full textAbstract:
Orientador: Cecília Amélia de Carvalho ZavagliaTese (doutorado) - Universidade Estadual de Campinas, Faculdade de Engenharia Mecânica
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Resumo: À medida que há uma melhoria na tecnologia aplicada à saúde humana, a expectativa de vida vem aumentando, mas nem todas as partes do corpo podem manter suas funções com o processo de envelhecimento. É preciso que os ossos e a cartilagem apóiem o envelhecimento do corpo, embora as células que os produzem se tornem menos ativas com o tempo. Outros órgãos, tais como os rins, o coração e o fígado devem ser operados para ter um tempo de vida maior. A engenharia tecidual foi desenvolvida para substituir, reparar ou reconstruir tecidos ou órgãos perdidos ou danificados por acidentes ou doenças graves através da utilização e desenvolvimento de novos materiais, que sejam biocompatíveis, bioabsorvíveis, porosos, entre outras características. Os scaffolds são arcabouços tridimensionais porosos e são utilizados na regeneração de tecidos para seu estado natural e suas funções, que é fundamental para a engenharia tecidual. Eles podem ser classificados em arcabouços que induzem a migração e o crescimento celular e em arcabouços carreadores de células osteogênicas autógenas, que foram colonizadas em biorreatores e subsequentemente reimplantadas no paciente. Tais scaffolds podem ser naturais ou sintéticos. O objetivo deste trabalho é avaliar o compósito poroso de hidroxiapatita - titânia (HATiO2), em três composições diferentes (50% HA - 50% TiO2, 60% HA - 40% TiO2, 70% HA - 30% TiO2) para obter scaffolds utilizados para engenharia tecidual óssea. Os corpos de prova foram produzidos pelo método da esponja polimérica, utilizando bicarbonato de sódio como ligante e floculante. A sinterização foi realizada em três temperaturas: a 1250ºC; 1300ºC e 1350ºC. As propriedades analisadas foram: resistência à compressão e dureza através das normas da ASTM, porosidade aparente, densidade aparente, retração linear de queima e absorção de água, pelo método de Souza Santos para argilas. Os resultados obtidos mostraram-se bastante satisfatórios, onde foi mostrado que os corpos cerâmicos porosos obtiveram valores de resistência à compressão e dureza coerentes com os da literatura e superiores aos da hidroxiapatita pura. Realizou-se também uma caracterização estrutural das amostras via difração de raios - x (DRX), microscopia eletrônica de varredura (MEV) e espectroscopia por infravermelho com transformada de Fourier (FT-IR). Com base nos resultados mecânicos e de caracterização estrutural, foi escolhida a amostra com composição de 50% HA - 50% TiO2 sinterizada a 1350ºC para realização de ensaios in vitro, onde foram avaliadas citotoxicidade e crescimento celular de osteoblastos e fibroblastos de camundongos. Os resultados indicaram que o compósito é biocompatível e que as células cresceram nos scaffolds. De forma geral, pode-se concluir que todas as amostras são indicadas para a utilização como matéria prima para aplicação em engenharia tecidual óssea. A amostra com 50% HA - 50% TiO2 apresentou melhores características para a realização dos ensaios in vitro realizados neste trabalho e pode-se indicar esta para a realização de ensaios in vivo, onde devem ser avaliadas as características de citotoxicidade e crescimento de células ósseas em animais, por um período de 15 e 30 dias, conforme normas da área de saúde
Abstract: As we witness an improvement in the technology applied to human health, life expectancy increases, even though not every part of the body can maintain their functions with the aging process. It is necessary that bones and cartilage support the body's aging, even if the cells that produce them become less active with time. Other organs, such as kidneys, heart and liver must be operated to have a higher lifetime. Tissue engineering has been developed in order to replace, repair or rebuild tissues or organs lost or damaged due to accidents or serious diseases through the use and development of new materials that are biocompatible, bioabsorbable, with porosity among other characteristics. Scaffolds are a kind of porous tridimensional net and they are used on tissues regeneration to their natural state and functions, which is fundamental for tissue engineering. They can be classified as scaffolds that induce migration and cell growth and as carrier scaffolds for autogenous ostheogenic cells, which were colonized inside bioreactors and then redeployed on the patient. Those scaffolds can be natural or synthetic. This research aimed to evaluate hydroxyapatite-titanium oxide (HA-TiO2) with three different compositions (50% HA - 50% TiO2, 60% HA - 40% TiO2, 70% HA - 30% TiO2) to obtain scaffolds used for bone tissue engineering. Samples were made by the polymeric sponge method, using sodium bicarbonate as a binder and flocculating agent. Sintering was carried out at 1250ºC; 1300ºC e 1350ºC. It was analyzed compressive strength and Vickers hardness using ASTM Standards, apparent porosity, apparent density, burning linear retraction and water absorption by Souza Santos method used for clays. Results proved satisfactory showing that ceramic bodies obtained compressive strength and Vickers hardness according to literature and higher than those for pure hydroxyapatite. Samples structural characterization was done by x-ray diffraction (XRD), scanning electronic microscopy (SEM) and Fourier transformed infrared (FT-IR). It was chosen 50% HA - 50% TiO2 sintered at 1350ºC based on its mechanical properties and structural characterization and in vitro essays were done to evaluate citotoxicity and mouse osteoblasts and fibroblasts cell growth. Results have shown that the composite is biocompatible and the cell growth above scaffolds surface. In general, samples can be recommended for use as raw material for bone tissue engineering application. The sample with 50% HA - 50% TiO2 showed better characteristics for in vitro essays done and it can be recommended for in vivo essays where citotoxicity and bone cell growth in animals during 15 and 30 days, according to health standards
Doutorado
Materiais e Processos de Fabricação
Doutor em Engenharia Mecânica
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Ropars, Ludovic. "Composites à matrice titane et renforts TiB élaborés par métallurgie des poudres : cinétique de transformations des phases, formation des microstructures et propriétés mécaniques." Thesis, Université de Lorraine, 2016. http://www.theses.fr/2016LORR0327/document.
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Les travaux réalisés dans cette thèse visent d’une part, à comprendre les évolutions structurales et microstructurales d’un composite à matrice titane et à renforts TiB au cours des différentes étapes d’élaboration par métallurgie des poudres et des traitements thermiques associés, et d’autre part, à établir des relations entre microstructures et propriétés mécaniques pour ce matériau. Les cinétiques de transformations des phases de la matrice et du renfort ont été caractérisées par DRX haute énergie in situ, au cours des différents traitements du cycle de fabrication. Des analyses de la microstructure par MEB, MEB EBSD et MET (EDX et EELS) complètent l’analyse par DRX. Il a été montré que les cinétiques de transformation de la matrice des composites sont fortement affectées (décalage d’environ 300°C vers les hautes températures de la température de transus ß) par le procédé de fabrication. Ce décalage a été associé à un enrichissement en éléments interstitiels dû au broyage mécanique des poudres et aux interstitiels présents dans les renforts TiB2 introduits pour former le TiB. L’étude in situ a aussi précisé la séquence de transformation du diborure de titane en borure TiB–B27 via la formation de la phase métastable TiB-Bf. Les analyses par MEB et MET ont permis d’atteindre et de discuter des évolutions morphologiques et spatiales des phases (matrice et borures) au cours des différents traitements, et de caractériser la composition chimique des borures. Une séquence de transformation du renfort est proposée. Enfin, des matériaux composites ont été élaborés et soumis à divers traitements thermomécaniques. Le lien entre les propriétés mécaniques statiques et les évolutions morphologiques des borures et de la matrice, comme de la texture des phases, a été abordé. Des traitements ont été proposés pour atteindre des propriétés optimalesThe work done in this PhD thesis aims at the understanding of, on the one hand, the structural and microstructural evolutions of a TiB reinforced titanium matrix composite during the various steps and treatments of the powder metallurgy route used to produce it, and, on the other hand, the link between the microstructures and the mechanical properties for this material. The phase transformation kinetics, in the matrix and in the reinforcement, were characterised using in situ high energy XRD, during these treatments. Microstructural analysis, using SEM, SEM-EBSD and TEM (EDX and EELS) complete the XRD analysis. The matrix phase transformation kinetics were shown to be highly impacted by the processing route (a 300°C shift toward the high temperatures is found for the ß transus temperature). This shift has been linked with an increase in interstitial elements, coming from the powder mechanical alloying and from the interstitials in the TiB2 powder used to produce the TiB. The in situ study also helped in clarifying the transformation sequence of the TiB2 into TiB-27, via the formation of the metastable phase TiB-Bf. SEM and TEM analysis allowed to get access to and discuss the morphological and spatial evolutions of the phases (matrix and borides) during the various treatments and to characterise the chemical composition of the borides. A transformation sequence has been proposed. Finally, in a last part, composite materials were elaborated and submitted to defined heat treatments. The link between the static mechanical properties and the morphological and texture evolutions in the matrix and in the borides, was discussed. Some treatments were proposed to reach optimum mechanical properties
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Fruhauf, Jean-Baptiste. "ELABORATION ET CARACTERISATION MECANIQUE DE COMPOSITES A MATRICE TITANE RENFORCES PAR DES PARTICULES DE TIC." Thesis, Saint-Etienne, EMSE, 2012. http://www.theses.fr/2012EMSE0670/document.
Full textAbstract:
Les propriétés spécifiques du titane en font un matériau de choix pour remplacer l’acier dans des applications où le poids est un paramètre de conception important. cependant, contrairement à l’acier, le titane souffre de mauvaises propriétés tribologiques. c’est pour répondre à cette problématique qu’il est envisagé de développer des composites à matrice métallique (cmm) titane renforcée par des particules de carbure de titane. dans le cadre de ce projet, plusieurs nuances de cmm à matrice ti ou ti-6al-4v contenants différentes fractions volumiques de particules de tic ont été élaborées par métallurgie des poudres. trois procédés ont été employés : le frittage libre, la compression isostatique à chaud et le filage. les différentes nuances ont ensuite été caractérisées du point de vue microstructurale (taux de densification, taille des grains) et mécanique (traction). la confrontation des résultats a permis d’établir un lien entre microstructure et propriétés mécaniques. dans l’optique d’étudier la mise en forme mais également d’améliorer les propriétés mécaniques, un post-traitement de type forgeage a été appliqué à la suite de la phase d’élaboration. excepté dans le cas des cmm filés, la présence de renforts entraîne l’apparition d’endommagement lors de la déformation à chaud. nous avons alors déterminé les conditions de forgeage les plus adaptées selon les nuances.finalement, à travers un travail de modélisation analytique et de simulation numérique par méthode d’homogénéisation, nous avons déterminé les grandeurs mécaniques (module de young et limite d’élasticité) et prévu la loi de comportement des cmm en tractionThe specific properties of titanium make it a key material for the replacement of steel in weight dependent applications. however, unlike steel, titanium suffers from poor wear resistance. in order to improve this weakness, it is proposed to develop titanium metal matrix composites (mmc) reinforced with titanium carbide particles.to this end, ti and ti-6al-4v mmc were prepared with reinforcement fractions ranging from 5 percent to 20 percent using three powder metallurgy techniques: free sintering, hot isostatic compression and extrusion. the composites were then characterized from a microstructural (density, grain size) and a mechanical (tensile test) point of view. by comparing the results, it was possible to establish a relationship between microstructural features and mechanical properties.following their preparation, the composites were subjected to a forging step in order to study their behavior during hot deformation and to further improve their mechanical properties. the presence of particles induces the apparition of damage during hot deformation. therefore, we determined the best forging for the different composites whilst taking microstructure into account.finally, through analytical modeling and numerical simulations, we determined the young modulus, the yield stress and predicted the behavior of a mmc during a tensile test
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Courleux, Alice. "Physico-chimie des échanges matrice/renfort dans un matériau composite acier/TiC." Phd thesis, Université Claude Bernard - Lyon I, 2011. http://tel.archives-ouvertes.fr/tel-00642978.
Full textAbstract:
Un composite à matrice métallique et à renfort particulaire de carbure de titane (25vol.%) produit par la société Mecachrome par métallurgie des poudres est l'objet de cette étude. Le process industriel suit trois étapes : broyage à haute énergie des poudres d'acier et de carbure de titane (TiC) ; consolidation de la poudre composite par extrusion ou consolidation isostatique à chaud (HIP) ; traitements thermiques d'austénitisation. Les principales évolutions concernent la taille de particule, la taille de cristallite, le paramètre de maille et la composition chimique du renfort TiC. Dans cette étude, nous nous sommes concentrés uniquement sur l'évolution du renfort (les évolutions de la matrice sont développées dans le travail de M. Mourot). Afin de caractériser les particules de TiC à chaque étape du process, nous avons mis en place une procédure de dissolution chimique sélective de la matrice acier. Le TiC ainsi " extrait " de la matrice a ensuite été caractérisé de façon méthodique par microscopie électronique à balayage (MEB), microscopie électronique en transmission (MET), diffraction des rayons X (DRX) et analyse chimique élémentaire. Ces techniques ont permis de révéler des changements importants indiquant des interactions physico-chimiques durant les étapes d'élaboration du composite. Ces évolutions du renfort et l'étude thermodynamique des systèmes C-Fe-Ti et C-Fe-O-Ti ont permis de proposer les mécanismes réactionnels à prendre en compte lors de l'élaboration du composite acier/TiC
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Jimoh, Abdulfatai. "In-situ particulate-reinforcement of titanium matrix composites with borides." Thesis, 2011. http://hdl.handle.net/10539/9323.
Full textAbstract:
Several research efforts have been directed towards in-situ fabrication of titanium
matrix composites (TMCs) from Ti and B4C powder mixtures as one of the ways to
improve the physical and mechanical properties of titanium and its alloys. In this
perspective, the present study reports the development of in-situ particulate
reinforced titanium matrix composites from TiH2-B4C and Ti-B6O powder mixtures
The relationship between densification and microstructure and mechanical properties
(hardness and fracture toughness) of pure Ti and in-situ reinforced titanium matrix
composites have been studied in detail using pressureless and hot-pressing
techniques. Titanium hydride powder was compacted into cylindrical pellets that
were used to produce pure Ti through dehydrogenation and pressureless sintering
technique. Various composition of TiH2-B4C powder mixtures were initially milled
using alumina balls in a planetary mill. The milling was to achieve homogeneous
mixing and distribution of the ceramic partially in the TiH2 powder, as well as
uniform distribution of reinforcing phases on the resulting Ti matrix.
Dehydrogenation and conversion of loose powder and compacts of TiH2 powder was
carried out in argon atmosphere and complete removal of hydrogen was achieved at
680 and 715oC for loose and compacted powder respectively. Pressureless sintering
of pure Ti from TiH2 was carried out between 750-1400oC, while pressureless
sintering and hot pressing of TiH2-B4C was carried out in the temperature
range1100-1400oC using 30MPa for hot pressed samples in argon atmosphere.
Different sintering times were considered. The microstructure and phase composition
of the sintered and hot-pressed materials were characterized using scanning electron
microscopy (SEM) and X-ray diffractometry (XRD). Densities of the sintered and hotpressed
materials were measured to determine the extent of densification, while
Vickers hardness and indentation fracture toughness were used to measure the
mechanical properties of the sintered and hot-pressed materials. Pure Ti from TiH2 showed higher densification of above 99% of theoretical density compared to literature where lower densification and swelling was observed. Its Vickers hardness is higher than that of commercial Ti sintered under the same conditions. Titanium matrix composites (TMCs) with different volume content of in-situ formed
reinforcements (TiB + TiC) were successfully produced. The amount of
reinforcements formed increases with increased amount of B4C used in the starting
powder mixtures, while the amount of needle-type TiB decrease and size and amount
of blocky-type TiB increase with increasing volume fraction of TiB. Dense materials
and improved Vickers hardness were achieved by the hot-pressed composites
especially at 1400oC compared to the pressureless sintered composites under the
same conditions and to the relevant literature. TMCs produced in this study show
higher Vickers hardness compared to available data in the literature. The hardness
was found to depend on the volume content of the reinforcing phases. However, the
fracture toughness obtained is low (5.3MPa.m1/2) in comparison to pure Ti but is
comparable with reported data in the literature.
The mechanisms leading to the achievement of improved densification and higher
hardness and the reasons for lower fracture toughness with different sintering
temperature and composition of reinforcements in the composites are critically
analysed. It has been shown that pure Ti can be pressureless sintered using TiH2 and
reinforced Ti matrix composites with improved densification and mechanical
properties can be produced from TiH2-B4C powder mixtures. Further work on the
comprehensive study of the mechanical properties of these composites would enhance
the industrial potential of using these materials and the processing route to produce
economically feasible titanium matrix composites
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Sypeck, David Joseph. "Damage evolution in titanium matrix composites /." 1996. http://wwwlib.umi.com/dissertations/fullcit/9701350.
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Chaudhuri, Karabi. "A study of metal matrix composites based on a titanium alloy." 1994. http://catalog.hathitrust.org/api/volumes/oclc/31535526.html.
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Thesis (Ph. D.)--University of Wisconsin--Madison, 1994.Typescript. eContent provider-neutral record in process. Description based on print version record. Includes bibliographical references (leaves 182-199).
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Tsang, Hsiao-Tsung, and 常孝宗. "A study on the process and mechanical behavior of titanium matrix In-situ composites." Thesis, 1997. http://ndltd.ncl.edu.tw/handle/87901890928260667327.
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博士國立交通大學
材料科學與工程學研究所
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The main objective of this dissertation is to study the processing and mechanical behavior of titanium matrix in-situ composites produced by combustion- assisted synthesis. Both systems of TiC/Ti and TiB/Ti were successfully fabricated by combustion-assisted synthesis which consisted of exothermic reactions and vacuum arc remelting. The effects of thermomechanical process (TMP) by hot-swaging on microstructure were explored. In addition to evaluation of tensile and compressive properties, fracture behavior was characterized by in-situ SEM observations and quantitative analyses of fracture surface from 298 K to 1022 K. Creep and fatigue crack propagation tests were carried out according to ASTM specification. The results in this study were summarized as follows： Both TiC/Ti and TiB/Ti composite systems with 5 to 20 vol. % in-situ reinforcements demonstrated a superior strength and ductility. This was attributed to the clean interface and good bonding strength of reinforcements as revealed by HRTEM observations and analyses of fracture behavior. The particle size of reinforcement increased with increasing volume fraction of reinforcement since the adiabatic temperature, the raised temperature for products due to heat of chemical reaction under adiabatic condition, increased with increasing volume fraction of reinforcement for both TiC/Ti and TiB/Ti systems. A linear relationship between interparticle distance (X) and reduction ratio of hot-swaging (R) for 10% TiC/Ti was established and expressed by λ(μm)＝18.57-0.21R (R≧4) Due to the refinement of TiC and the decrease of interparticle distance by TMP, tensile strength (σ) at both ambient and elevated temperatures can be significantly enhanced. The relation of σ in proportional to l/λ indicated that the strengthening mechanism of titanium matrix in-situ reinforced composite at room temperature followed the Orowan mechanism. Based on the in-silu SEM observations, the tensile fracture process at room temperature for TiC/Ti composite consisted few stages, including reinforcement protrusion, cracking in small particles, cracking in larger particles and coalescence of large cracks. There is an obvious transition temperature at 645 K for fracture mechanism being changed from particle cracking to interparticle voiding. The creep mechanism of present titanium matrix in-situ composites, which was proved to be diffusion controlled dislocation climb, was identical to that of Ti matrix. All creep data of pure Ti and composites were merged together, which had the true stress exponent of 4.2 after compensating effects of the modulus, threshold stress and particle size. A constitution equation of creep for present Ti-based in-situ composites was proposed as The fatigue crack growth rate (FCGR) of titanium matrix in-situ composite at 723 K was approximately one order lower than that at 298 K for same applied stress intensity range under same stress ratio of R=O.1, showing a disparity tendency in comparison with matrix metal. All data of FCGR merged very well after crack closure correction. The difference in fatigue crack growth behavior at room and elevated temperatures was interpreted by crack closure. The mechanism of microcrack-induced crack closure was proposed to account for improvement of fatigue crack growth resistance at elevated temperatures.
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Aghachi, Izendu Emenike Alu. "Dynamic stress analysis of composite structures under elastic wave load : particulate reinforced metal matrix composites." 2012. http://encore.tut.ac.za/iii/cpro/DigitalItemViewPage.external?sp=1000194.
Full textAbstract:
D. Tech. Mechanical Engineering.Discusses the main objective of this study was to extend the hybrid method developed by Paskaramoorthy, et al (1988). This objective was to study the effect of elastic wave on any particulate reinforced metal matrix composite (PRMMC). The specific objectives were: to compare the effect of plane wave and shear vertical wave on a particular particulate reinforced metal matrix composite (PRMMC)-Mg/TiC, using analytical method ; to use the extended hybrid method to determine the effect of particle size and single interface layer on Mg/TiC.
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(8802758), Mohamed G. Elkhateeb. "Multiscale Modeling of the Mechanical Behaviors and Failures of Additive Manufactured Titanium Metal Matrix Composites and Titanium Alloys Based on Microstructure Heterogeneity." Thesis, 2020.
Find full textAbstract:
This study is concerned with the predictive modeling of the machining and the mechanical behaviors of additive manufactured (AMed) Ti6AlV/TiC composites and Ti6Al4V, respectively, using microstructure-based hierarchical multiscale modeling. The predicted results could constitute as a basis for optimizing the parameters of machining and AM of the current materials.
Through hierarchical flow of material behaviors from the atomistic, to the microscopic and the macroscopic scales, multiscale heterogeneous models (MHMs) coupled to the finite element method (FEM) are employed to simulate the conventional and the laser assisted machining (LAM) of Ti6AlV/TiC composites. In the atomistic level, molecular dynamics (MD) simulations are used to determine the traction-separation relationship for the cohesive zone model (CZM) describing the Ti6AlV/TiC interface. Bridging the microstructures across the scales in MHMs is achieved by representing the workpiece by macroscopic model with the microscopic heterogeneous structure including the Ti6Al4V matrix, the TiC particles, and their interfaces represented by the parameterized CZM. As a result, MHMs are capable of revealing the possible reasons of the peculiar high thrust forces behavior during conventional machining of Ti6Al4V/TiC composites, and how laser assisted machining can improve this behavior, which has not been conducted before.
Extending MHMs to predict the mechanical behaviors of AMed Ti6Al4V would require including the heterogeneous microstructure at the grain level, which could be computational expensive. To solve this issue, the extended mechanics of structure genome (XMSG) is introduced as a novel multiscale homogenization approach to predict the mechanical behavior of AMed Ti6Al4V in a computationally efficient manner. This is realized by embedding the effects of microstructure heterogeneity, porosity growth, and crack propagation in the multiscale calculations of the mechanical behavior of the AMed Ti6Al4V using FEM. In addition, the XMSG can predict the asymmetry in the Young’s modulus of the AMed Ti6Al4V under tensile and compression loading as well as the anisotropy in the mechanical behaviors. The applicability of XMSG to fatigue life prediction with valid results is conducted by including the energy dissipations associated with cyclic loading/unloading in the calculations of the cyclic response of the material.
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"Synthesis of TiC particulate-reinforced aluminum matrix composites =: 碳化鈦顆粒增強的鋁基複合材料的合成硏究." 1999. http://library.cuhk.edu.hk/record=b5896332.
Full textAbstract:
Ka-fai Ho.Thesis (M.Phil.)--Chinese University of Hong Kong, 1999.
Includes bibliographical references.
Text in English; abstracts in English and Chinese.
Ka-fai Ho.
Acknowledgments --- p.i
Abstract --- p.ii
摘要 --- p.iv
Figures Captions --- p.v
Tables Captions --- p.xii
Table of contents --- p.xiii
Chapter Chapter one --- Introduction --- p.1-1
Chapter 1.1 --- Metal Matrix Composite --- p.1-1
Chapter 1.1.1 --- Matrix Materials --- p.1-2
Chapter 1.1.1.1 --- Aluminum --- p.1-2
Chapter 1.1.1.2 --- Titanium --- p.1-3
Chapter 1.1.2 --- Type of reinforcements --- p.1-3
Chapter 1.2 --- Conventional Fabrication method --- p.1-4
Chapter 1.2.1 --- Liquid Phase processing --- p.1-4
Chapter 1.2.1.1 --- Slurry deposition --- p.1-4
Chapter 1.2.1.2 --- Squeeze casing (Pressure infiltration) --- p.1-4
Chapter 1.2.2 --- Solid Phase processing --- p.1-5
Chapter 1.2.2.1 --- Diffusion bonding --- p.1-5
Chapter 1.2.2.2 --- Powder Metallurgy (P/M) --- p.1-5
Chapter 1.2.3 --- In-situ processing --- p.1-7
Chapter 1.3 --- Sintering processing --- p.1-7
Chapter 1.3.1 --- Pore structure --- p.1-8
Chapter 1.3.2 --- Compression effect on sintering --- p.1-9
References
Chapter Chapter Two --- Methodology and Instrumentation --- p.2-1
Chapter 2.1 --- Al-Ti-C composites --- p.2-1
Chapter 2.1.1 --- Introduction --- p.2-1
Chapter 2.1.2 --- Aim and Motivation --- p.2-2
Chapter 2.1.2.1 --- Compositions and Fabrications --- p.2-2
Chapter 2.1.2.2 --- Testing --- p.2-3
Chapter 2.1.3 --- The Flow of the Thesis --- p.2-3
Chapter 2.2 --- Instrumentation --- p.2-4
Chapter 2.2.1 --- Ball-milling machine --- p.2-4
Chapter 2.2.2 --- High temperature furnace --- p.2-5
Chapter 2.2.3 --- Arc-melting furnace --- p.2-5
Chapter 2.2.4 --- Instron loading machine --- p.2-6
Chapter 2.2.5 --- Density measurement --- p.2-6
Chapter 2.2.6 --- Vickers' Hardness Tester --- p.2-8
Chapter 2.2.7 --- X-ray diffraction analysis --- p.2-8
Chapter 2.2.8 --- Scanning Electron Microscope (SEM) and Energy Dispersive X-ray Spectroscopy (EDXS) --- p.2-9
References
Chapter Chapter Three --- Fabrication of Al-16Ti-C composites by Powder Metallurgy method --- p.3-1
Chapter 3.1 --- Introduction --- p.3-1
Chapter 3.2 --- Experiments --- p.3-1
Chapter 3.2.1 --- Experiments on Pressing pressure --- p.3-1
Chapter 3.2.2 --- Firing temperature and duration time --- p.3-2
Chapter 3.3 --- Results --- p.3-2
Chapter 3.3.1 --- Pressing pressure --- p.3-2
Chapter 3.3.1.1 --- Relative Density --- p.3-2
Chapter 3.3.1.2 --- Surface Porosity --- p.3-2
Chapter 3.3.1.3 --- Microhardness --- p.3-3
Chapter 3.3.1.4 --- X-ray diffraction analysis --- p.3-3
Chapter 3.3.1.5 --- Microstructure --- p.3-3
Chapter 3.3.2 --- Firing temperature and duration time --- p.3-4
Chapter 3.3.2.1 --- Microhardness --- p.3-4
Chapter 3.3.2.2 --- X-ray diffraction analysis --- p.3-4
Chapter 3.3.2.3 --- Microstructure --- p.3-4
Chapter 3.4 --- Discussion --- p.3-5
Chapter 3.4.1 --- Pressing pressure --- p.3.5
Chapter 3.4.2 --- Firing temperature and time duration --- p.3-6
Chapter 3.5 --- Conclusions --- p.3-6
References
Chapter Chapter Four --- Effects of the size of Aluminum powder on the properties of Al-16Ti-4C composites --- p.4-1
Chapter 4.1 --- Introduction --- p.4-1
Chapter 4.2 --- Experiments --- p.4-1
Chapter 4.3 --- Results --- p.4-2
Chapter 4.3.1 --- Relative density --- p.4-2
Chapter 4.3.2 --- Microhardness --- p.4-3
Chapter 4.3.3 --- Fracture Strength --- p.4-3
Chapter 4.3.4 --- X-ray diffraction analysis --- p.4-3
Chapter 4.3.5 --- Microstructure --- p.4-4
Chapter 4.3.5.1 --- Microstructure of the surface --- p.4-4
Chapter 4.3.5.2 --- Microstructure of the fracture surface --- p.4-4
Chapter 4.4 --- Discussion --- p.4-5
Chapter 4.4.1 --- Sintering procedure --- p.4-5
Chapter 4.4.2 --- Fracture model --- p.4-6
Chapter 4.4.3 --- X-ray diffraction analysis --- p.4-6
Chapter 4.5 --- Conclusions --- p.4-7
References
Chapter Chapter Five --- Effects of different sintering temperature on the properties of Al-16Ti-4C composites --- p.5-1
Chapter 5.1 --- Introduction --- p.5-1
Chapter 5.2 --- Experiments --- p.5-1
Chapter 5.3 --- Results --- p.5-2
Chapter 5.3.1 --- Relative density --- p.5-2
Chapter 5.3.2 --- Microhardness --- p.5-2
Chapter 5.3.3 --- Fracture Strength --- p.5-2
Chapter 5.3.4 --- X-ray diffraction analysis --- p.5-2
Chapter 5.3.5 --- Microstructure --- p.5-3
Chapter 5.3.5.1 --- Surface microstructure --- p.5-3
Chapter 5.3.5.2 --- Fracture surface microstructure --- p.5-3
Chapter 5.4 --- Discussion --- p.5-3
Chapter 5.4.1 --- Sintering procedure and microstructure --- p.5-3
Chapter 5.4.2 --- Hardness and fracture strength --- p.5-4
Chapter 5.4.3 --- Model of fracture --- p.5-5
Chapter 5.5 --- Conclusions --- p.5-5
Chapter Chapter Six --- Fabrication of TiC by Arc melting method --- p.6-1
Chapter 6.1 --- Introduction --- p.6-1
Chapter 6.2 --- Experiments --- p.6-2
Chapter 6.3 --- Results --- p.6-2
Chapter 6.3.1 --- X-ray diffraction analysis --- p.6-2
Chapter 6.3.2 --- Microstructure --- p.6-2
Chapter 6.4 --- Discussion --- p.6-2
Chapter 6.4.1 --- Composition --- p.6-2
Chapter 6.4.2 --- Sintering process --- p.6-3
Chapter 6.5 --- Conclusions --- p.6-3
References
Chapter Chapter Seven --- The Effects of the contents of Ti and C on the properties of Al-TiC and Al-Ti-C composites --- p.7-1
Chapter 7.1 --- Introduction --- p.7-1
Chapter 7.2 --- Experiments --- p.7-1
Chapter 7.3 --- Results --- p.7-2
Chapter 7.3.1 --- Relative density --- p.7-2
Chapter 7.3.2 --- Microhardness --- p.7-2
Chapter 7.3.3 --- Fracture Strength --- p.7-2
Chapter 7.3.4 --- X-ray diffraction analysis --- p.7-3
Chapter 7.3.5 --- Microstructure --- p.7-3
Chapter 7.3.5.1 --- Surface microstructure --- p.7-3
Chapter 7.3.5.2 --- Fracture surface microstructure --- p.7-4
Chapter 7.4 --- Discussion --- p.7-4
Chapter 7.4.1 --- Hardening effect --- p.7-4
Chapter 7.4.2 --- Relationship between fracture strength and relative density --- p.7-4
Chapter 7.4.3 --- Fracture model --- p.7-5
Chapter 7.5 --- Conclusions --- p.7-5
References
Chapter Chapter Eight --- Conclusions and Future Work --- p.8-1
Chapter 8.1 --- Summary --- p.8-1
Chapter 8.2 --- Future Work --- p.8-2
References
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Iggulden, Roy Charles. "A study of the chemical stability and the mechanial tailorability of interfaces in coated alumina reinforced titanium metal matrix composites." 1996. http://catalog.hathitrust.org/api/volumes/oclc/36680080.html.
Full textAbstract:
Thesis (M.S.)--University of Wisconsin--Madison, 1996.Typescript. eContent provider-neutral record in process. Description based on print version record. Includes bibliographical references (leaves 91-93).