Dissertations / Theses on the topic 'Aluminium alloy'
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1
Matthews, Stephen John. "Cavitation erosion of aluminium alloys, aluminium alloy/ceramic composites and ceramics." Thesis, Coventry University, 1993. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.317927.
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Nafisi, Shahrooz. "Effects of grain refining and modification on the microstructural evolution of semi-solid 356 alloy = Effets de l'affinage des grains et de la modification sur l'évolution microstructurale de l'alliage 356 semi-solide /." Thèse, Chicoutimi : Université du Québec à Chicoutimi, 2006. http://theses.uqac.ca.
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Golbahar, Behnam. "Effect of grain refiner-modifier interaction on the performance of A356.2 alloy." Thèse, Chicoutimi : Université du Québec à Chicoutimi, 2008. http://theses.uqac.ca.
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Thèse (M.Eng.) -- Université du Québec à Chicoutimi, 2008.La p. de t. porte en outre: Mémoire présenté à l'Université du Québec à Chicoutimi comme exigence partielle de la maîtrise en ingénierie. CaQQUQ Comprend des réf. bibliogr. (f. 149-155). Publié aussi en version électronique. CaQQUQ
4
Turner, Michael. "Brush plating of bearing alloys on aluminium alloy shells." Thesis, Aston University, 1986. http://publications.aston.ac.uk/11919/.
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The turbocharging of diesel engines has led to increase in temperature, load and corrosive attack of plain bearings. To meet these requirements, overlay plated aluminium alloys are now preferred. Currently, lead-tin alloys are deposited using a zincate layer and nickel strike, as intermediate stages in the process. The nickel has undesirable seizure characteristics and the zincate can given rise to corrosion problems. Consequently, brush plating allows the possible elimination of these stages and a decrease in process together with greater automation. The effect of mode application, on the formation of zincate films, using film growth weight measurements, potential-time studies, peel adhesion testing and Scanning Electron Microscopy was studied, for both SIC and AS15 aluminium alloys. The direct plating of aluminium was also successfully achieved. The results obtained indicate that generally, although lower adhesion resulted when a brush technique was used, satisfactory adhesion for fatigue testing was achieved. Both lead-tin and tin-cobalt overlays were examined and a study of the parameters governing brush plating were carried out using various electrolytes. An experimentally developed small scale rig, was used to produce overlay plated bearings that were fatigue tested until failure. The bearings were then examined and an analysis of the failure mechanisms undertaken. The results indicated that both alloy systems are of the regular codeposition type. Tin-cobalt overlays were superior to conventional lead-tin overlays and remained in good condition, although the lining (substrate) failed. Brush plated lead-tin was unsatisfactory. Sufficient understanding has now been gained, to enable a larger scale automated plant to be produced. This will allow a further study of the technique to be carried out, on equipment that more closely resembles that of a full scale production process.
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Ghadimzadeh, Seyed Reza. "Machining of hypereutectic aluminium-silicon alloy." Thesis, Coventry University, 1995. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.281726.
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Chayong, Sukangkana. "Thixoforming processing of aluminium 7075 alloy." Thesis, University of Sheffield, 2002. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.251217.
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Trejo, Eduardo. "Centrifugal casting of an aluminium alloy." Thesis, University of Birmingham, 2011. http://etheses.bham.ac.uk//id/eprint/3041/.
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In centrifugal casting, molten metal is introduced into a mould which is rotated at high speed. The centrifugal force helps to fill thin sections but this benefit may be offset by the effect of the turbulent flow on the casting quality. In this research, the effect of direct and indirect gated mould designs on the quality and reliability of aluminium alloy investment castings made by centrifugal casting was investigated. The scatter in the ultimate bend strength and the modulus of elasticity was analyzed using the Weibull statistical technique, which showed that the Weibull modulus of both properties was significantly improved for the indirect gated cast test bars compared to the direct gated bars. A detailed microstructural characterization was carried out on the cast test bars, which included grain size, dendrite cell size and porosity. Scanning electron microscopy was used to examine and analyze the presence of defects on the fracture surfaces such as shrinkage pores, entrapped bubbles and oxide films resulting from surface turbulence during mould filling. The results indicated a clear correlation between the mechanical properties and the presence of casting defects. Water modelling experiments were carried out using purpose-built experimental centrifugal casting equipment and filling sequences recorded using a high speed video camera. The water modelling results showed that the general tendency for the direct and indirect gated mould designs was that the higher the rotational velocity, the lower the filling length and consequently the lower the filling rate. Subsequently, this information was used to validate the computer software ANSYS CFX. An excellent correlation was obtained between the experimental water modelling and simulation results for both direct and indirect gated moulds.
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Subramaniyan, Jaya. "Extrusion of 2024 aluminium alloy sections." Thesis, Imperial College London, 1989. http://hdl.handle.net/10044/1/47677.
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Garcia-Vergara, Sandra Judith. "Effects of alloy enrichment in the surface properties of aluminium alloys." Thesis, University of Manchester, 2004. https://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.507256.
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Willis, T. C. "Melt spun Al alloy." Thesis, University of Oxford, 1985. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.354869.
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Gao, Zhaoli. "CNT-TIM fabrication on aluminium alloy substrates /." View abstract or full-text, 2010. http://library.ust.hk/cgi/db/thesis.pl?MECH%202010%20GAO.
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Nosair, S. I. M. "Fatigue crack growth in aluminium alloy structures." Thesis, University of Salford, 1986. http://usir.salford.ac.uk/26840/.
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Fatigue cracks have been reported in the super structure of the surface ships in the navy. Repair techniques have been proposed and applied on compact tension specimens. Such techniques were; either by creating compressive residual stresses using welding anisotropy, local plastic deformation and spot heating. Or, constraining the crack tip using tightened bolt or steel/carbon fibre patches. Complete F.C.G. data were obtained for the metal in the as-rolled and welded conditions. A metallurgical study has also been made. Fractography, the influence of residual stresses and second phases have been studied. The study showed that superior crack resistance was obtained from spot heated specimens, which were very simple to prepare. Considerable retardation was also obtained using welding anisotropy, local plastic deformation and tightened bolts. Patching seems to provide limited improvement. The influence of compressive residual stress was found to improve the crack resistance. The influence of the inclusions was found to depend on their morphology. Medium sized and homogeneously distributed inclusions provided a retarding effect on the crack speed. More inclusion interaction was reported in the presence of residual stresses.
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Skeete, Zito. "Thermomechanical processing of particulate aluminium alloy compounds." Thesis, Imperial College London, 2001. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.248420.
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Wei, Wu. "Study of sensitization in AA5083 aluminium alloy." Thesis, University of Manchester, 2017. https://www.research.manchester.ac.uk/portal/en/theses/study-of-sensitization-in-aa5083-aluminium-alloy(5ffe8730-859f-4823-9d08-d31bd1fd5fff).html.
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An AA5083 aluminium alloy sensitized in service after 40 years exposure to ground atmosphere temperature is studied. Nitric acid mass loss test (NAMLT) is used to determine the susceptibility to intergranular corrosion (IGC). The degree of sensitization in various areas through the alloy thickness was found different, which can be associated with non-homogeneous Mg distribution through the alloy plate thickness. Structure characterisation confirmed that the in-service sensitization is associated with the formation of the ' phase and a cubic Al-Mg transition phase with magnesium content between the GP zones and the '' phase at the grain boundaries. In order to simulate the in-service sensitization process and to gain insight into the sensitization mechanism, the sensitization of AA5083 alloy at relatively low temperatures, namely 70 and 100°C, is studied. For the AA5083 alloy sensitized at 70°C, although the mass loss value is below 15 mg/cm2, ' phase is observed as individual precipitates at grain boundaries. The AA5083 alloy after exposure to 100°C for 240 hours is susceptible to IGC since the ' precipitates have grown continuously at the grain boundaries. Additionally, the effect of sensitization in AA5083 alloy on stress corrosion cracking (SCC) is also investigated using constant displacement double cantilever beam (DCB) testing. It is found that the cracking length increases with the degree of sensitization. The population density of the crack branches also increases with the degree of sensitization. The metal between different small branches is known as ligament. And with high degree of sensitization, the ligaments between crack branches have become brittle. Therefore, small branches became connected to form a continuous crack with the crack propagating.
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Meluch, Lubos. "Warm compaction of aluminium alloy Alumix 123." Thesis, University of Birmingham, 2010. http://etheses.bham.ac.uk//id/eprint/709/.
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The aims of this study were to understand and improve the mechanical properties of aluminium Al-Cu-Si-Mg P/M alloy Alumix 123 by application of a warm compaction process. They were achieved by investigating the effect of (a) compaction pressure/temperature, (b) admixed lubricants (e.g. Acrawax C and Kenolube P11) on green/sintered density and mechanical properties of compacts. It was found that compaction at 110ºC led to (1) a reduction in the ejection force up to ~ 40 % and (2) an increase in sintered density up to ~ 98 % of theoretical density. After heat treatment at 200ºC for 5 hours (T6), the tensile strength reached ~ 365 MPa and hardness of ~ 126 HV was achieved. Further improvement of mechanical properties of aluminium alloy Alumix 123 can be achieved by reducing the amount of admixed lubricant to 0.5 wt %, and using Acrawax C as the lubricant rather than Kenolube P11. Taguchi analysis was used to identify which parameter (compaction pressure, temperature and lubricant content) affected the densities and mechanical properties of Alumix 123 specimens with single lubricants the most. It was observed that the most effective parameter in warm compaction of Alumix 123 specimens is the lubricant content.
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Haddleton, Frank L. "The properties of advanced aluminium alloy systems." Thesis, Aston University, 1987. http://publications.aston.ac.uk/11896/.
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2XXX and 7XXX series aluminium alloys have been the accepted materials for airframe construction for many decades. However, only minor improvements in properties have been possible by the development of these alloys since the early 1970's. The constant need to reduce weight in aircraft has therefore led to a resurgence in the research for higher performance aluminium alloys. The reason for this investigation was to evaluate possible alternatives for the existing conventional aluminium alloy 2014 for aircraft wheel applications. Three new technologies in alloy development were considered: a metal matrix composite, an aluminium-lithium alloy and a powder metallurgical alloy. The basic mechanical properties of these advanced materials have already been established to an extent, but their fatigue behaviour has yet to be fully understood. The purpose of this work was to investigate the fatigue properties of the materials concerned, in both air and an aerated 3.5% NaCl solution, and compare these properties to 2014-T6. As well as the basic mechanical properties, fatigue crack propagation data is presented for all of the materials concerned. Additionally, fatigue crack initiation data is presented for the aluminium-lithium alloy and 2014. The D.C. electrical potential method was used to monitor crack growth. Of the materials investigated, the most promising was the aluminium-lithium alloy. However, short transverse properties need to be increased and the commercial cost of the material needs to be decreased before it can be considered as a direct replacement for 2014 for aircraft structural applications. It was considered that the cost of the powder metallurgical alloy would limit its further use. The metal matrix composite material proved to be unsuitable for most ambient temperature applications.
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Al-Jumaili, Omar Saad Salih. "Investigation of friction stir welding of aluminium alloy and aluminium matrix composites." Thesis, University of Nottingham, 2018. http://eprints.nottingham.ac.uk/55637/.
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Friction stir welding (FSW) is an upgraded version of the conventional friction welding process, and it is considered the latest development and the most important one during the past two decades in the welding of metals. The dependence of FSW on friction and plastic work as a heat source precludes the melting in the workpiece and leads to avoiding many of the difficulties arising from the change in the state of the material, such as defects, distortion and residual stresses, which often happen in conventional welding processes. FSW gained significant attention as a solid-state welding process of aluminium alloys, but now there is a need to extend its application to advanced materials such as metal matrix composites (MMCs). However, the process has always represented a challenge owing to the complexity of microstructural development and the associated number of process parameters to take into consideration. This thesis investigates the feasibility of welding two new advanced aluminium matrix composites (AMCs), AA 6092/SiC/17.5p-T6 and AA 6061B/SiC/20p-T1 by FSW for the first time. Also, aluminium alloy AA6082-T6 has been investigated as base-line material to specify the benefit, drawback, and FSW window. Experiment analyses were conducted to evaluate the influence of FSW parameters, including tool rotation and traverse speeds on the quality of weldments. Weld joints were characterised in terms of thermal history, metallurgical behaviour, mechanical properties, and residual stresses. The metallurgical characterisations have been done by optical, scanning electron microscopy (SEM), electron backscattered diffraction (EBSD), transmission electron microscopy (TEM), and energy dispersive X-ray spectroscopy (EDS). Microhardness, tensile, and low-cycle fatigue (LCF) test with the axial total strain-amplitude control mode R=ε_min⁄(ε_max=-1) were used for evaluating the mechanical properties. The results showed that the generated peak temperature in the welding joints is affected more significantly by the rotating tool speed, while the exposure time and subsequent cooling rate are controlled by tool traverse speed. The microstructure of nugget zone (NZ) exhibits an elliptical shape with a substantial grain refinement resulted from continuous dynamic recrystallisation (CDR) process with an increase in the fraction of high angle grain boundaries (HAGBs). The evolved grain size was greatly influenced by weld pitch as the ratio between tool traverse speed to tool rotation speed, which is a key parameter to control the amount of heat input, exposure time and cooling rate. In addition, in the case of AMCs more homogeneous distribution of reinforcement particles (SiC) coupled with particle refinement were formed in the NZ. The cross-weld microhardness profile revealed a significant difference in microhardness among the base metals, heat affected zone (HAZ), thermo-mechanically affected zone (TMAZ), and NZ in the case of AA 6082 and AMC (AA 6092/SiC/17.5p), as they depend on the strengthening precipitate. Meanwhile, the hardness profile of AMC (AA 6061B/SiC/20p) FSW joints showed that there is no difference in the measured hardness between the welding zone and base materials because the welded joints are exposed to thermal history similar to the initial heat treatment condition of the base metal, T1, cooled from an elevated temperature shaping process and naturally aged. The tensile strength of AA6082, and AMC (AA 6092/SiC/17.5p) cross-weld FSW specimens was found to be lower than their base metals with a joint efficiency (the ratio of the tensile strength of joint to the tensile strength of base metal) of about 71 and 75 %, respectively. While for SAMC (AA 6061B/SiC/20p) FSW joints it is reached 108 % of that of the base metal. The low-cycle fatigue results indicate that the fatigue life of the cross-weld joints varies with grain size in the NZ, and it is always lower than that of the base metal. A significant improvement in fatigue life is found to be related to the finer equiaxed grains dominated by HAGBs in the NZ, as well as, to less gradient in the grain size of the cross-weld. Residual stresses are significant concerns associated with the welding process, as it can combine with applied stresses, which may lead to the reduction of structural properties. The result of residual stress measurement by neutron diffraction techniques exhibited a typical ''M'' profile, which indicates that compressive and tensile residual stress existed in the base metal and welding zone, respectively. This has not only provided an improved understanding of residual stresses in FSW joints but also has contributed to the validation of 3D fully coupled thermo-mechanical finite element (FE) model, which has been developed based on Coupled Eulerian-Lagrangian (CEL) technique. The model is also used to predict the thermal history and material flow in the FSW of aluminium alloy AA6082. The numerical results showed a good agreement with the experimental results.
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Urbanczyk, Robert, Kateryna Peinecke, Michael Felderhoff, Klaus Hauschild, Wolfgang Kersten, Stefan Peil, and Dieter Bathen. "Aluminium alloy based hydrogen storage tank operated with sodium aluminium hexahydride Na3AlH6." Elsevier, 2014. https://publish.fid-move.qucosa.de/id/qucosa%3A36284.
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Here we present the development of an aluminium alloy based hydrogen storage tank, charged with Ti-doped sodium aluminium hexahydride Na3AlH6. This hydride has a theoretical hydrogen storage capacity of 3 mass-% and can be operated at lower pressure compared to sodium alanate NaAlH4. The tank was made of aluminium alloy EN AW 6082 T6. The heat transfer was realised through an oil flow in a bayonet heat exchanger, manufactured by extrusion moulding from aluminium alloy EN AW 6060 T6. Na3AlH6 is prepared from 4 mol-% TiCl3 doped sodium aluminium tetrahydride NaAlH4 by addition of two moles of sodium hydride NaH in ball milling process. The hydrogen storage tank was filled with 213 g of doped Na3AlH6 in dehydrogenated state. Maximum of 3.6 g (1.7 mass-% of the hydride mass) of hydrogen was released from the hydride at approximately 450 K and the same hydrogen mass was consumed at 2.5 MPa hydrogenation pressure. 45 cycle tests (rehydrogenation and dehydrogenation) were carried out without any failure of the tank or its components. Operation of the tank under real conditions indicated the possibility for applications with stationary HT-PEM fuel cell systems.
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Wu, Weili. "The modeling of hot tearing in aluminium alloy." Thèse, Chicoutimi : Université du Québec à Chicoutimi, 2003. http://theses.uqac.ca.
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Jaradeh, Majed M. R. "The effect of processing parameters and alloy composition on the microstructure formation and quality of DC cast aluminium alloys /." Stockholm : Materialvetenskap Materials Science and Engineering, 2006. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-4205.
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Bhattacharya, Victoria. "Study Of Friction And Wear Behaviour Of Nano-Embedded Aluminium Alloys." Thesis, Indian Institute of Science, 2000. https://etd.iisc.ac.in/handle/2005/190.
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In general, the bearing alloys have two types of microstructure i.e., either a soft matrix with discrete hard particles or a continuous matrix of the harder metal with small amount of the softer metal finely dispersed in it. The aluminium and copper based bearing alloys which are widely studied fall in the second category. However, the bearing materials which have been studied have micron sized dispersoids. In recent times, it is possible to produce nanoscale dispersoids in a hard matrix by the novel processing route of rapid solidification. This offers an opportunity to study the small length scale effect on tribological processes. In this thesis, we deal with aluminium alloys where nanoscaled dispersions of lead, bismuth and indium are produced by rapid solidification processing. Chapter 1 of the thesis is an introduction, followed by Chapter 2, which reviews the literature on nanomaterials. Special attention is given to the monotectic system, followed by a brief description on friction and wear of materials which is necessary for our present investigation. The details of experimental and characterisation techniques are given in Chapter 3. In Chapter 4, we present a brief study of white metal bearings (babbit). Tin-based babbit of composition, Sn-6wt% Cu-llwt% Sb was studied. The study of babbit was mainly carried out with the idea that it could serve as a benchmark for subsequent studies in aluminium alloys, in terms of tribological properties. In particular, we have carried out a detailed electron microscopic investigation on the phases present in the bearing alloy. The friction and wear behaviour of this material confirms the proper calibration of our setup for wear studies. This is followed by a detailed study on the synthesis, microstructure and tribological behaviour of nanodispersed aluminium alloys, Al-6wt% Pb and Al-10wt% Pb in Chapter 5.
For comparison, we have also studied melt-spun aluminium without dispersoids. Detailed electron microscopic characterisation indicates that lead has a cube on cube orientation relationship with the aluminium matrix, and the particles exhibit a lognormal distribution with the mode of the particle size distribution being 15 nm. The pin on disc results suggest a distinct lowering of coefficient of friction corresponding to pure aluminium (μ= 0.40) and as cast aluminium-lead alloys (μ= 0.41). Detailed SEM studies indicate a tribolayer consisting primarily of Al, Pb and Fe. The later comes from the counterface material. Our results clearly indicate that at an early stage, little or no oxidation takes place at the sliding interface. TEM observations indicate significant deformation of lead particles in the sub-surface region. The observations suggest spreading of the lead, which acts as a lubricating layer. Wear behaviour is primarily adhesive and follows Archard's wear law. However, the rate of wear is less than that reported by other investigators on micronsized lead dispersions in aluminium. In Chapter 6, we present the results for alloys dispersed with nanosized indium and bismuth. We show that indium particles on melt-spinning exhibit both cubic and tetragonal crystal structure. The indium particles are coarser (with a mode of 25 nm) than the lead and bismuth particles (which have mode of 15nm). The bismuth containing alloys have a lower wear rate and coefficient of friction compared to lead and indium alloys. However, both indium and bismuth particles do not follow Archard's wear law and the wear vs load graph shows a non-linear behaviour. The results are discussed in terms of known mechanisms of the coefficient of friction and wear. Chapter 7 gives the salient conclusions while in Chapter 8 we discuss some of the unanswered questions and the potential for future work in this field.
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Bhattacharya, Victoria. "Study Of Friction And Wear Behaviour Of Nano-Embedded Aluminium Alloys." Thesis, Indian Institute of Science, 2000. http://hdl.handle.net/2005/190.
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In general, the bearing alloys have two types of microstructure i.e., either a soft matrix with discrete hard particles or a continuous matrix of the harder metal with small amount of the softer metal finely dispersed in it. The aluminium and copper based bearing alloys which are widely studied fall in the second category. However, the bearing materials which have been studied have micron sized dispersoids. In recent times, it is possible to produce nanoscale dispersoids in a hard matrix by the novel processing route of rapid solidification. This offers an opportunity to study the small length scale effect on tribological processes. In this thesis, we deal with aluminium alloys where nanoscaled dispersions of lead, bismuth and indium are produced by rapid solidification processing. Chapter 1 of the thesis is an introduction, followed by Chapter 2, which reviews the literature on nanomaterials. Special attention is given to the monotectic system, followed by a brief description on friction and wear of materials which is necessary for our present investigation. The details of experimental and characterisation techniques are given in Chapter 3. In Chapter 4, we present a brief study of white metal bearings (babbit). Tin-based babbit of composition, Sn-6wt% Cu-llwt% Sb was studied. The study of babbit was mainly carried out with the idea that it could serve as a benchmark for subsequent studies in aluminium alloys, in terms of tribological properties. In particular, we have carried out a detailed electron microscopic investigation on the phases present in the bearing alloy. The friction and wear behaviour of this material confirms the proper calibration of our setup for wear studies. This is followed by a detailed study on the synthesis, microstructure and tribological behaviour of nanodispersed aluminium alloys, Al-6wt% Pb and Al-10wt% Pb in Chapter 5.
For comparison, we have also studied melt-spun aluminium without dispersoids. Detailed electron microscopic characterisation indicates that lead has a cube on cube orientation relationship with the aluminium matrix, and the particles exhibit a lognormal distribution with the mode of the particle size distribution being 15 nm. The pin on disc results suggest a distinct lowering of coefficient of friction corresponding to pure aluminium (μ= 0.40) and as cast aluminium-lead alloys (μ= 0.41). Detailed SEM studies indicate a tribolayer consisting primarily of Al, Pb and Fe. The later comes from the counterface material. Our results clearly indicate that at an early stage, little or no oxidation takes place at the sliding interface. TEM observations indicate significant deformation of lead particles in the sub-surface region. The observations suggest spreading of the lead, which acts as a lubricating layer. Wear behaviour is primarily adhesive and follows Archard's wear law. However, the rate of wear is less than that reported by other investigators on micronsized lead dispersions in aluminium. In Chapter 6, we present the results for alloys dispersed with nanosized indium and bismuth. We show that indium particles on melt-spinning exhibit both cubic and tetragonal crystal structure. The indium particles are coarser (with a mode of 25 nm) than the lead and bismuth particles (which have mode of 15nm). The bismuth containing alloys have a lower wear rate and coefficient of friction compared to lead and indium alloys. However, both indium and bismuth particles do not follow Archard's wear law and the wear vs load graph shows a non-linear behaviour. The results are discussed in terms of known mechanisms of the coefficient of friction and wear. Chapter 7 gives the salient conclusions while in Chapter 8 we discuss some of the unanswered questions and the potential for future work in this field.
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Cano-Castillo, U. "Environment-assisted cracking of spray-formed Al-alloy and Al-alloy-based composite." Thesis, University of Oxford, 1995. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.260730.
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Elabar, Dawod. "Effect of sulphate impurity in chromic acid anodizing of aluminium and aluminium alloy." Thesis, University of Manchester, 2016. https://www.research.manchester.ac.uk/portal/en/theses/effect-of-sulphate-impurity-in-chromic-acid-anodizing-of-aluminium-and-aluminium-alloy(ec562f6a-6bc9-4bb4-9eee-468d539f90a2).html.
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In this work, the nucleation and growth of pores in anodic films formed on aluminium in chromic acid and the effect of low levels of sulphate impurity in the anodizing bath on the formation of the films on aluminium and AA 2024 alloy are investigated. The sulphate concentrations considered include levels within specified limits for industrial processing. The anodizing is carried out either potentiostatically or by stepping the voltage. The films are examined by scanning electron microscopy, transmission electron microscopy and atomic force microscopy to determine the pore spacing, pore population densities, pore diameters and film thicknesses. Film compositions were determined using energy-dispersive X-ray spectroscopy, Rutherford backscattered microscopy and nuclear reaction analysis. In order to investigate the mechanism of pore formation, two tracer methods are employed. In one method, anodic films are formed first in an arsenate electrolyte in the second method, a tungsten tracer band deposited by magnetron sputtering. The behaviours of arsenic and the tungsten are investigated during the subsequent anodizing in chromic acid. The results suggest that the initiation and growth of pores in occurred as a result of electric field assisted chemical dissolution. The effect of sulphate impurity in the chromic acid is investigated using electrolytes with different sulphate content. In the initial stages of anodizing aluminium at 100 V, sulphate impurity at a level of 38 ppm in the chromic acid is shown to lead to significant incorporation of sulphate ions into the anodic film, a lower current density, a smaller cell size and less feathering of the pore walls. In addition, the efficiency of film formation is increased. In later stages of anodizing, the growth of larger pores and cells, leads to a duplex film morphology, with finer pores in the outer region. The change in pore size correlates with a reduction in the incorporation of sulphate into the film. From the results of sequential anodizing experiments, it is suggested that incorporated sulphate ions generate a space charge layer, which has an important role in determining the current density. The effects of higher sulphate concentrations up to 3000 ppm are investigated, which are shown to significantly affect the current density and the pore diameter. Anodizing of aluminium and AA 2024 alloy was also carried out according to industrial practice. The results show that there is significant effect of sulphur impurity on the film thickness. Corrosion tests in 3.5 % NaCl solution for the alloy after anodizing in low (smaller or equal to 1.5 ppm) and high (~38 ppm) sulphate-containing chromic acid electrolytes demonstrate a better corrosion resistance with films formed in the latter electrolyte.
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Green, Andrew Morgan. "Environmentally-assisted crack growth in aluminium alloy 7475." Thesis, University of Cambridge, 1990. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.359748.
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Przydatek, Jan. "The elevated temperature deformation of aluminium alloy 2650." Thesis, Imperial College London, 1998. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.287577.
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O'Dwyer, John Gerard. "Creep performance of SiCp reinforced aluminium alloy 2618A." Thesis, Imperial College London, 1999. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.313719.
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Hung, Richard Liang Che. "Microstructural development in a commercial aluminium lithium alloy." Thesis, Brunel University, 1999. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.266543.
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Manson-Whitton, Chris. "Squeeze casting of a conventionally wrought aluminium alloy." Thesis, University of Oxford, 2004. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.403577.
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Mirzaii, Hossein. "Fatigue behaviour of adhesively bonded aluminium alloy joints." Thesis, Imperial College London, 1992. http://hdl.handle.net/10044/1/11836.
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Su, Meini, and 蘇玫妮. "Behaviour and design of aluminium alloy structural elements." Thesis, The University of Hong Kong (Pokfulam, Hong Kong), 2014. http://hdl.handle.net/10722/206728.
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Aluminium alloys are nonlinear metallic materials with continuous stress-strain curves that are not well represented by the simplified elastic, perfectly plastic material model used in most existing design specifications. The aims of this study are to develop a more efficient design method for aluminium alloy structures by rationally exploiting strain hardening. The key components of this study include laboratory testing, numerical modelling and development of design guidance for aluminium alloy structures.
As part of the present study, the experimental programme included tests on 11 stub columns, 40 simply supported beams, 46 continuous beams and corresponding tensile coupon tests. Numerical investigations of aluminium alloy simply supported beams and continuous beams were also conducted. The validated finite element models were used for extensive parametric studies, generating 96 results for beams under three-point bending, 96 under four-point bending and 210 for continuous beams. The experiments and numerical simulations have shown the following key features of the inelastic behaviour of aluminium alloy structural elements: (1) the significance of strain hardening, indicated by the ultimate stress over the yield stress, could be up to 50%; (2) non-slender section capacities could be generally up to 40% higher than the yield limits in compression, and 50% greater than the plastic moments in bending; (3) the experimental and numerical ultimate loads of continuous beams on non-slender sections go beyond the calculated loads corresponding to the occurrence of the first hinge by more than 10%.
Previous experimental data on aluminium alloy stub columns and simply supported beams were also collected. These collected test data were used together with the newly generated experimental and numerical results obtained from this study, totalling about 900 data, to assess the design predictions of the American, Australian/New Zealand and European specifications. On average, the existing design methods under-estimated the capacity of aluminium alloy stub columns by around 15%~22%, simply supported beams by around 18%~40% and continuous beams by around 27% ~ 50%. Existing section classification limits in Eurocode 9 (2007) were also assessed, and while they were found to be safe, some improved limits were proposed.
The combined experimental and numerical results were used to develop and calibrate a new design method, termed the continuous strength method (CSM). Two key components of the CSM – a base curve and a bi-linear material model for aluminium alloys have been proposed in this study. Global plastic analysis allowing for moment redistribution has also been adopted in the CSM. Unlike current practices, the CSM has the merits of adopting the continuous treatment for the cross-section deformation response, rationally exploiting the available capacity beyond the yield limit and reasonably allowing for redistributing the internal forces.
The capacity predictions of aluminium alloy structural members have been improved by more than 30% using the CSM. Reliability analyses have also been performed to assess the reliability level of different design methods according to the American Institute of Steel Construction (2010) and European Standard EN1990 (2002) approaches. The CSM has been shown to be safe, efficient and consistent for aluminium alloy structural members.published_or_final_version
Civil Engineering
Doctoral
Doctor of Philosophy
32
Rushforth, Mark William. "The fatigue of adhesively bonded aluminium alloy AA5754." Thesis, University of Birmingham, 2003. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.410282.
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Walker, John Christopher. "Lubricated sliding wear of some aluminium alloy composites." Thesis, University of Sheffield, 2006. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.434551.
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Hobson, Anthony James. "The thermal stability of aluminium-lithium alloy 8090." Thesis, University of Southampton, 1999. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.287033.
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35
Davies, Raymond John. "The durability of an adhesively bonded aluminium alloy." Thesis, Imperial College London, 1990. http://hdl.handle.net/10044/1/46276.
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Su, Meini. "Behaviour and design of aluminium alloy structural elements." Thesis, Imperial College London, 2014. http://hdl.handle.net/10044/1/25588.
Full textAbstract:
Aluminium alloys are nonlinear metallic materials with continuous stress-strain curves that are not well represented by the simplified elastic, perfectly plastic material model used in most existing design specifications. The aims of this study are to develop a more efficient design method for aluminium alloy structures by rationally exploiting strain hardening. The key components of this study include laboratory testing, numerical modelling and development of design guidance for aluminium alloy structures. As part of the present study, the experimental programme included tests on 11 stub columns, 40 simply supported beams, 46 continuous beams and corresponding tensile coupon tests. Numerical investigations of aluminium alloy simply supported beams and continuous beams were also conducted. The validated finite element models were used for extensive parametric studies, generating 96 results for beams under three-point bending, 96 under four-point bending and 210 for continuous beams. The experiments and numerical simulations have shown the following key features of the inelastic behaviour of aluminium alloy structural elements: (1) the significance of strain hardening, indicated by the ultimate stress over the yield stress, could be up to 50%; (2) non-slender section capacities could be generally up to 40% higher than the yield limits in compression, and 50% greater than the plastic moments in bending; (3) the experimental and numerical ultimate loads of continuous beams on non-slender sections go beyond the calculated loads corresponding to the occurrence of the first hinge by more than 10%. Previous experimental data on aluminium alloy stub columns and simply supported beams were also collected. These collected test data were used together with the newly generated experimental and numerical results obtained from this study, totalling about 900 data, to assess the design predictions of the American, Australian/New Zealand and European specifications. On average, the existing design methods under-estimated the capacity of aluminium alloy stub columns by around 15%~22%, simply supported beams by around 18%~40% and continuous beams by around 27% ~ 50%. Existing section classification limits in Eurocode 9 (2007) were also assessed, and while they were found to be safe, some improved limits were proposed. The combined experimental and numerical results were used to develop and calibrate a new design method, termed the continuous strength method (CSM). Two key components of the CSM - a base curve and a bi-linear material model for aluminium alloys have been proposed in this study. Global plastic analysis allowing for moment redistribution has also been adopted in the CSM. Unlike current practices, the CSM has the merits of adopting the continuous treatment for the cross-section deformation response, rationally exploiting the available capacity beyond the yield limit and reasonably allowing for redistributing the internal forces. The capacity predictions of aluminium alloy structural members have been improved by more than 30% using the CSM. Reliability analyses have also been performed to assess the reliability level of different design methods according to the American Institute of Steel Construction (2010) and European Standard EN1990 (2002) approaches. The CSM has been shown to be safe, efficient and consistent for aluminium alloy structural members.
37
Owen, Nigel. "The fracture behaviour of an aluminium lithium alloy." Thesis, Imperial College London, 1987. http://hdl.handle.net/10044/1/47559.
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Olakanmi, Eyitayo Olatunde. "Direct selective laser sintering of aluminium alloy powders." Thesis, University of Leeds, 2008. http://etheses.whiterose.ac.uk/1476/.
Full textAbstract:
The SLS/SLM of aluminium powder had been investigated by studying the effect of powder properties and laser processing parameters on the microstructures and properties of both single layer and multiple layer builds. On the basis of experimental evidence, the SLS/SLM of aluminium powders could be categorised into full melting (SLM) which was found to have occurred in both pure and pre-alloyed aluminium powders, and binary liquid phase sintering (SLS) which occurred in blended bimodal or trimodal powders. That successful disruption of the oxide film is possible is a significant result, as is the constitutional effect on this. The spheroidisation and oxide disruption phenomena in SLS/SLM processed aluminium powders arc suggested to be mainly controlled by the amount of oxide on the as-received powder's surface, the degree of the uniformity of the distribution of the surface oxide film covering the aluminium particles as well as the nature of thermal mismatch existing between the oxide film and the parent aluminium particle which was dependent on the phase present in the oxide film (alumina, mullite, and spinel). It was discovered that the attainment of high sintered density and desirable microstructural properties in the blended aluminium powders is consequent upon the determination of the right processing conditions, appropriate choice of powders (in terms of particle size distribution, spherical particle shape, and component ratio). Moreover, it is now evident that chemical constitution of the blended aluminium powders only becomes influential in the determination of the properties of SLS processed parts when the choice of processing parameters and powder properties are correct. The choice of powder properties determines the thermal conductivity of the powder bed which in effect controls the sintered properties. This had been inferred from the relationship between powder tapping density on one hand, and selective laser sintered (SLS) density, dendrite spacing and fraction of primary phase on the other hand. In making smaller samples, it has been shown that the attainment of high sintered density (up to 90%) and a good microstructure are feasible. These arc accompanied by reasonable hardness values, comparable to those of cast Al-12wt%Si castings. In fabricating larger sized parts for mechanical testing, defects such as delamination became more noticeable leading to poor mechanical properties in those samples. Thus, it is now clear that physical limitations of the sintering machine hinder the production of SLS/SLM processed parts having excellent structural integrity. On the basis of this work, it is envisaged that the use of pre-alloyed Al-Si powders of uniform composition, but a wider particle size and size distribution, blended to optimise the bed density, offers the potential to produce light alloy components by SLS. In conclusion, the specific laser energy input, the component ratio, and the particle size and size distribution of the powder were found to have strongly influenced the densitication mechanism and the solidification process in a small sized aluminium powdered part fabricatedb y SLS/SLM process.
39
Lashkari, Omid. "The rheological behavior of semi-solid A356 alloy." Thèse, Chicoutimi : Université du Québec à Chicoutimi, 2006. http://theses.uqac.ca.
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Thèse (D.Eng.) -- Université du Québec à Chicoutimi, 2006.La p. de t. porte en outre: Dissertation presented to the University of Quebec at Chicoutimi in partial fulfilment of the requirement for the degree of doctor of philosophy in engineering. CaQCU Bibliogr.: f. 177-184. Document électronique également accessible en format PDF. CaQCU
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Yan, Feng. "Development of high strength Al-Mg2Si-Mg based alloy for high pressure diecasting process." Thesis, Brunel University, 2014. http://bura.brunel.ac.uk/handle/2438/13883.
Full textAbstract:
Aluminium alloys are the most promising lightweight materials used in the automotive industry to achieve weight reduction for improving fuel efficiency and reducing CO2 emissions. High pressure diecasting (HPDC) is a fast and economical near-net shape manufacturing method to produce engineering components. About 80% of cast aluminium alloys are currently manufactured by HPDC. The increased demands of manufacturing structural components by HPDC process require high strength Al-alloys for the automotive industry. However, the currently available die cast Al-alloys are unable to fulfil this requirement. Al-Mg2Si alloy is known as an alloy capable of providing superior high strength by Mg2Si particles. However, Al-Mg2Si alloy is not applicable in the HPDC process because of the severe die soldering problem. This has limited its applications throughout industries. Moreover, the existing studies on the Al-Mg2Si alloy are mainly focused on the hyper-eutectic alloys and limited information is available for hypo-eutectic alloys. Generally, the mechanical properties of Al-alloys are determined by the alloy composition, the defect levels in the components, the microstructure which is mainly controlled by the casting process and heat treatment process. Due to the high cooling rate provided by the die block in the HPDC process, the refined microstructure in the die cast Al-Mg2Si alloys can be obtained to improve the mechanical properties. Therefore, the development of high strength Al-Mg2Si based alloys for the HPDC process is significant for manufacturing quality automotive components. The present study mainly focuses on the alloy development for the HPDC process. In order to make die castable Al-Mg2Si based alloys, the effect of excess Mg has been investigated to modify the hypo-eutectic Al-Mg2Si system for improving the mechanical properties. The effect of excess Mg on the solidification and microstructural evolution, and the mechanical properties of Al-Mg2Si alloys, has also been investigated by the combination of thermodynamic calculation and the experimental validation. The excess Mg in the hypo-eutectic Al-Mg2Si alloys has been found to be able to shift the eutectic composition to a lower Mg2Si content, which means that the hypo-eutectic composition of Al-Mg2Si alloy can be at eutectic or hyper-eutectic compositions after adding different levels of excess Mg. The experimental trials have also found that Al-8Mg2Si-6Mg alloy provides the best combination of strength and ductility in the as-cast castings made by the HPDC process. This can be further enhanced by adding 0.6wt.% Mn, which exhibits yield strength of 189MPa, UTS of 350MPa, and elongation of 6.5%. Investigations have also revealed that the Al-8Mg2Si-6Mg alloy exhibits a relatively high tolerance to the Fe impurity because of the insignificant reduction of ductility of the alloy. The elongation is still at a level of 5% when Fe is at 1.6wt.% in the alloy. Furthermore, Cu and Zn can further enhance the mechanical properties of the Al-8Mg2Si-6Mg-0.6Mn alloy. Cu contents between 0.31wt.% and 0.92wt.% in the Al-8Mg2Si-6Mg-0.6Mn alloy can increase the yield strength from 193MPa to 207MPa, but decrease the UTS from 343MPa to 311MPa, and the elongation from 4.8% to 3.8% under as-cast condition. This can be attributed to the formation of hot tearing defects in castings. Therefore, the Cu content in the alloy should be limited to a low level. On the other hand, zinc can be controlled to a level of 4.3wt.%, which will dramatically increase the tensile strength of the alloy. More importantly, Zn can significantly increase the mechanical properties of the alloy after a quick T6 heat treatment under a condition of solution at 490oC for 15 mins and ageing at 180oC for 90 mins, at which the yield strength is 345MPa, UTS is 425MPa, and elongation is 3.2 %. In the present study, the solidification and microstructural evolution, the relationship between the microstructure and mechanical properties, and the strengthening mechanisms in the developed alloy are discussed on the basis of the experimental results. A two stage solidification has been recognised to be responsible for the microstructure formation in the HPDC process. The primary α-Al phase is formed as prior phase for the hypo-eutectic alloy and the primary Mg2Si phase is formed as prior phase for the hyper-eutectic alloy. The solute elements including Mg, Mn, Fe, Cu, and Zn can enhance the solution strengthening and/or the precipitation strengthening in the alloys, but alter the solidification ranges, which will affect the formation of defects in the castings. In the quick T6 heat treatment, the AlMgZn phase is dissolved into the Al phase during solution treatment and precipitated during ageing treatment. The quick heat treatment is also found to be able to spheroidise the Mg2Si phase. Only η′ MgZn phase is precipitated during aging in Zn containing alloys. The alloy with 4.3wt.% Zn provides the best combination of the mechanical properties because of the high density of MgZn precipitates in the α-Al phase.
41
Yang, Deyu. "Rôle d'addition de magnésium sur l'occurence de la fonte naissante dans les alliages expérimentaux et commerciaux Al-Si-Cu et son influence sur la microstructure et les propriétés de traction de l'alliage = Role of magnesium addition on the occurence of incipient melting in experimental and commercial Al-Si-Cu alloys and its influence on the alloy microstructure and tensile properties /." Thèse, Chicoutimi : Université du Québec à Chicoutimi, 2006. http://theses.uqac.ca.
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Ganguly, Supriyo. "Non-destructive measurement of residual stresses in welded aluminium 2024 airframe alloy." Thesis, n.p, 2004. http://ethos.bl.uk/.
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Santoro, Gianmarco. "Mixed alloy chip extrusion." Bachelor's thesis, Alma Mater Studiorum - Università di Bologna, 2018.
Find full textAbstract:
The aim of the investigation is to characterize the behaviour of billets composed of different aluminium alloys chips, shape and size. The billets were processed by plastic deformation in order to obtain useful parameters to make final products with good aesthetic-structural characteristics. This is made possible by direct recycle of chips with plastic deformation processes, in specific with a chip-based hot extrusion process. This technique is very interesting at an industrial level where the chips coming from various aluminium alloy machining procedures are accumulated together.
The classic secondary aluminium production process by re-melting already saves 95% of energy in comparison to primary aluminium production from mineral (Bauxite). As previously shown from researches on Chip Extrusion, there is a higher energy saving through direct extrusion of chips and scraps pre-compacted in chip-based billets without re-melting.
The research has the objective of testing the optimal combination of process parameters for different mixes of alloys in order to obtain the desired profiles; at the same time a FEM (Finite Element Method) simulation is implemented with HyperExtrude and MatLab software. The code is expected to describe processes with different parameters and give results similar to the experimental ones.
44
Singh, Harshmeet. "The corrosion behaviour of aluminium alloy B206 in seawater." Thesis, University of British Columbia, 2016. http://hdl.handle.net/2429/56551.
Full textAbstract:
Aluminium alloy B206 is one of the strongest and toughest alloys in the cast aluminium family. Although it is light and has excellent low cycle fatigue strength, AA B206 has been known to perform adversely due to its poor corrosion resistance. Thus corrosion has been identified as one of the major issues that jeopardizes the long-term use and performance of B206. The corrosion behaviour of B206 in seawater is studied through immersion testing and electrochemical techniques such as Potentiodynmaic Polarization, Potentiostatic Polarization, Cyclic Potentiodynmic Polarization and Linear Sweep Thermmametry in two different solutions, namely natural seawater and simulated seawater, at various temperatures. Techniques like Optical Microscopy, Energy Dispersive X-ray Spectroscopy and Scanning Electron Microscopy have been used to investigate the microstructure and surface morphology before and after the electrochemical tests. Heat treatment has been performed on the as-received samples using RRA and T7 heat treatment techniques to compare the corrosion behaviour of the former with the latter using electrochemical techniques and image analysis. Lastly, hardness tests have been performed on various heat treated and as-cast samples to establish a comparison in mechanical properties. This study shows that the extent of B206 corrosion depends on the oxidizing nature of the seawater environment i.e. low or high redox potential rather than on the temperature of the seawater. Natural seawater is more aggressive than simulated seawater. Also, heat treatment improved the corrosion resistance as compared to as-cast B206 which was determined by the values of corrosion current density and surface analysis. Furthermore, heat treatment has led to better mechanical properties as determined by hardness tests.Applied Science, Faculty of
Materials Engineering, Department of
Graduate
45
Phoplonker, M. A. "Stable crack growth in an aluminium-silicon bronze alloy." Thesis, University of Portsmouth, 1987. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.378074.
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Williams, Paul Mathew. "Microstructural control of a novel aluminium - lithium - manganese alloy." Thesis, Brunel University, 1996. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.294902.
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Kang, Hyung-gu. "Locally reinforced squeeze cast aluminium alloy metal matrix composites." Thesis, University of Oxford, 1995. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.294391.
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Dodd, A. "Fatigue crack growth in an aluminium-lithium (8090) alloy." Thesis, University of Nottingham, 1988. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.381174.
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Spurr, G. J. "Fretting wear of a fine particulate reinforced aluminium alloy." Thesis, University of Nottingham, 1994. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.260524.
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Geary, B. "The superplastic deformation characteristics of aluminium alloy, Supral 220." Thesis, University of Manchester, 1985. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.370419.
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