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Matulich, Ryan Douglas. "Post-fire Mechanical Properties of Aluminum Alloys and Aluminum Welds." Thesis, Virginia Tech, 2011. http://hdl.handle.net/10919/32727.
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The focus of this research was to quantify the post-fire mechanical properties of 5083-H116 and 6082-T6 aluminum alloys. Post-fire exposure is considered heating the material to a particular temperature then cooling the material back to room temperature. The research included evaluating parent materials as well as welded samples.
Post-fire mechanical properties of parent materials were evaluated at temperatures ranging from ambient to 500oC with isothermal and transient heating. Changes in material properties were evaluated through static tensile tests and hardness testing on cooled samples. Using this data, an assessment was performed to investigate the relationship between hardness and mechanical properties. For the alloys evaluated, empirical relationships were found between Vickers hardness and post-fire strength.
Testing was also performed on butt welded samples of 6082-T6 exposed isothermally to temperatures ranging from ambient to 500oC. Vickers hardness profiles were measured across a sample to quantify the hardness of the weld, heat affected zone, and parent material. This was performed at room temperature and following different heat exposures. Static tensile tests were used to evaluate the effect of reheating on the welded samples. Post-fire strength of welded samples was strongly affected by weld geometry. Parent material hardness varied with reheating while weld hardness remained constant. At select temperatures, this resulted in the weld having a higher Vickers hardness than the parent material. Despite this tensile failure always occurred within the weld.Master of Science
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Sun, Ning. "Friction stir processing of aluminum alloys." Worcester, Mass. : Worcester Polytechnic Institute, 2009. http://www.wpi.edu/Pubs/ETD/Available/etd-050109-144331/.
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Eaton, James Allen. "Effect of temperature and percent cold work on the mechanical properties of aluminum alloy 3104." Master's thesis, This resource online, 1992. http://scholar.lib.vt.edu/theses/available/etd-03302010-020243/.
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Morgan, David Scott. "A microstructural and mechanical analysis of perforation of aluminum alloys." Thesis, Georgia Institute of Technology, 1992. http://hdl.handle.net/1853/16361.
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Paray, Florence. "Heat treatment and mechanical properties of aluminum-silicon modified alloys." Thesis, McGill University, 1992. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=41146.
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The commercial applications of cast Al-Si alloys depend to an important extent on controlling the morphology of the eutectic silicon through thermal modification in the solid state and/or chemical modification of the melt before the production of the casting. The effects of modification and/or heat treatment on the microstructure and the mechanical properties of 356 alloy have been investigated on both permanent mold and sand cast samples. Strontium (0.02%) and sodium (0.01%) were used to produce well modified microstructures. The importance of the amount of modifier used was also examined in producing castings with 0.002% Sr and 0.08% Sr. Production parameters such as solution heat treatment time and artificial aging time were examined.Microstructural assessment was done by quantitative metallography using image analysis coupled to SEM while mechanical testing comprised tensile testing, hardness and microhardness measurements as well as impact tests.
The greatest improvement in mechanical properties obtained with modification was observed for the lower rates of solidification, i.e sand casting. The effect of modification on the heat treatment response of 356 alloy was investigated. The differences between unmodified and modified microstructures were more important in sand cast samples than in permanent mold cast samples. After one hour of solution heat treatment at 540$ sp circ$C, both permanent mold unmodified and modified microstructures became similar in terms of silicon particle size and sphericity. The processes which led to this were different. Silicon platelets in the unmodified structures segmented while silicon particles in the modified alloy coarsened. The final result was however the same. In sand cast alloy, the initial microstructural differences persisted after up to 12 hours of solution treatment. The coarser the initial as-cast microstructure, the greater the improvements associated with modification and heat treatment.
It was also found that porosity caused by modification can negate many of the microstructural benefits by decreasing tensile strength and percent elongation. It was demonstrated that modification also has an influence on the aluminum matrix. The hardness of modified alloy was found to be less after the T6 temper than in unmodified alloy. This was reflected in a lower yield strength of modified 356 alloy.
Quantitative microstructure-mechanical property relationships were established for the permanent mold samples. The best silicon-structure characteristics to predict the tensile properties were found to be the particle count per unit area and the particle area.
It was also determined that hardness can be a simple and inexpensive means whereby ultimate tensile strength and yield strength of 356 alloy in the T4 condition or T6 condition can be estimated.
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Dighe, Manish D. "Quantitative characterization of damage evolution in an Al-Si-Mg base cast alloy." Thesis, Georgia Institute of Technology, 1998. http://hdl.handle.net/1853/20219.
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Sun, Ning. "Friction Stir Processing of Aluminum Alloys." Digital WPI, 2012. https://digitalcommons.wpi.edu/etd-dissertations/552.
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Friction stir processing (FSP) has been developed based on the basic principles of friction stir welding (FSW), a solid-state joining process originally developed for aluminum alloys. What is attractive about FSP is that it can be incorporated in the overall manufacturing cycle as a post-processing step during the machining operation to provide localized modification and control of microstructures in near-surface layers of metallic components. FSP has emerged as an important post-processing technique, and has been identified as a process that may have a high impact, and perhaps is a disruptive manufacturing process. In this study, FSP has been applied to Al cast alloy A206, which is a high strength, widely used cast alloy in the manufacturing industry. Motivations behind this work are to (1) investigate the feasibility of FSP on manipulating the cast microstructure and strengthening the material, and (2) to explore the viability of FSP to produce a localized particle reinforced zone in cast A206 aluminum components. The thesis will show that we have optimized FSP for processing of Al alloys to locally manipulate the cast microstructure, eliminate casting defects, and attain grain refinement and second phase homogenization. We have established the mechanism leading to the microstructure evolution and have evaluated the resultant mechanical properties, i.e. hardness, tensile property and fatigue properties. We have also synthesized a localized composite material in the A206 work piece with three different reinforcement materials via FSP. These results will be presented and discussed.
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Fuller, Christian B. "Temporal evolution of the microstructures of Al(Sc, Zr) alloys and their influence on mechanical properties." Full text available, 2003. http://images.lib.monash.edu.au/ts/theses/fuller.pdf.
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Bond, Trevor. "Microstructure and Mechanical Properties of Cold Sprayed Aluminum and Titanium Alloys." Digital WPI, 2019. https://digitalcommons.wpi.edu/etd-theses/1336.
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A combination of experimental and computational methods is used to explore the microstructure and mechanical behavior of cold sprayed 6061 aluminum alloy and Ti-6Al-4V alloy and their substrate materials. A variety of microscopic methods are used for characterization of the microstructure. The indentation size effect and characteristic length of strain gradient plasticity for the substrate materials are determined. An FEA simulation describes the behavior of a worn Berkovich nanoindenter. Stress strain is studied experimentally in the substrate materials for future comparison with bulk cold-sprayed materials. Abaqus FEA models are used to simulate a single particle impact for a particle with an oxide layer using a linear Johnson-Cook plasticity model and a bilinear Johnson-Cook plasticity model. The implications of the results are discussed for cold spray processes.
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Nittala, Aditya Kameshwara. "Electrical and Mechanical Performance of Aluminum Alloys with Graphite Nanoparticles." Ohio University / OhioLINK, 2019. http://rave.ohiolink.edu/etdc/view?acc_num=ohiou1554117521295178.
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Agarwal, Himanshu. "Effect of loading condition, stress state and strain on three-dimensional damage evolution in 6061 wrought Al-alloy." Thesis, Georgia Institute of Technology, 2001. http://hdl.handle.net/1853/14798.
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Hwang, Junyeon Kaufman M. J. "Characterization and mechanical properties of nanoscale precipitates in modified Al-Si-Cu alloys using transmission electron microscopy and 3D atom probe tomography." [Denton, Tex.] : University of North Texas, 2007. http://digital.library.unt.edu/permalink/meta-dc-3661.
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Gharghouri, Michael. "Study of the mechanical properties of Mg-8.5wt%Al by in-situ neutron diffraction /." *McMaster only, 1996.
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Riddle, Yancy Willard. "Al₃(Sc₁₋x, Zrx) dispersoids in aluminum alloys : coarsening and recrystallization control." Diss., Georgia Institute of Technology, 2000. http://hdl.handle.net/1853/20139.
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Giles, Tanya L. "The effect of friction stir processing on the microstructure and mechanical properties of AF/C458 aluminum lithium alloy." Thesis, Monterey, Calif. : Springfield, Va. : Naval Postgraduate School ; Available from National Technical Information Service, 2005. http://library.nps.navy.mil/uhtbin/hyperion/05Sep%5FGiles.pdf.
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Williams, Robert A. "A microstructural and mechanical property correlation of friction stir processed nickel aluminum bronze." Thesis, Monterey, Calif. : Springfield, Va. : Naval Postgraduate School ; Available from National Technical Information Service, 2004. http://library.nps.navy.mil/uhtbin/hyperion/04Sep%5FWilliams%5FR.pdf.
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Lamb, Justin. "Decomposition and its effects on mechanical properties in Al-Zn-Mg-Cu alloys." Diss., Georgia Institute of Technology, 2016. http://hdl.handle.net/1853/54931.
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The effects of variations in composition on the decomposition process in Al-Zn-Mg-Cu alloys (i.e. – 7xxx-series aluminum alloy) were studied emphasizing their effect on mechanical properties. Several experimental quaternary alloys were studied to compare their behavior with commercial 7xxx-series alloys. The investigation included studies on the effects of natural aging, artificial aging, quench sensitivity, precipitate free zone formation, and homogenization. Additionally, “true aging” curves (i.e. – hardness/strength vs. conductivity) were presented in order to visualize and quantify the entire precipitation process.
It is obvious that fluctuations in the main alloying elements/processing parameters can alter the precipitation process, but the purpose of this work was to quantify those changes using standard industrial techniques. It was found that natural aging was detrimental for strength in the T6 temper for alloys containing more than 1.0 wt.% Cu, and was shown to alter the coarsening kinetics in the over-aged condition (T7). Conversely, for alloys with Cu contents less than 0.5% natural aging was shown to be beneficial for strength. Altering the Zn:Mg ratio was also shown to effect natural aging response of an alloy in addition to introducing additional precipitation processes (T-phase). Therefore, this work is a blueprint for advanced alloy manufacturing that allows for the rapid production of new alloys and tempers by narrowing the research focus depending on an alloy’s composition.
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Crepeau, Paul Noles. "The effect of processing and microstructure on the mechanical properties of aluminum alloy 339-T5." Diss., Georgia Institute of Technology, 1989. http://hdl.handle.net/1853/20193.
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Khamsuk, Sunisa. "Changes in Microstructure and Mechanical Properties of Aluminum Alloys Heavily Deformed by Torsion." 京都大学 (Kyoto University), 2013. http://hdl.handle.net/2433/180617.
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Yan, Shi. "Strengthening Aluminum By Zirconium and Chromium." Digital WPI, 2013. https://digitalcommons.wpi.edu/etd-theses/3.
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The Al-Zr system is used to form a thermally stable strengthening phase in high temperature aluminum-base casting alloys. These alloys have good strength at elevated temperature due to the precipitation of coherent metastable Al3Zr particles upon decomposition of the supersaturated Al-Zr solid solution by a carefully designed heat treatment. Formation of the Al3Zr particles occurs by a peritectic reaction, which decrees that once formed, the particles cannot be dissolved by a solid-state homogenization process. Accordingly, melting the alloy must serve as the homogenization step of the precipitation hardening process; and solidification during casting must serve as the quenching step. Unfortunately, a prohibitively fast solidification rate is necessary to obtain a solid solution with as little as 0.4% Zr in Al. It is found that adding Cr to Al-0.4wt%Zr binary alloy makes it easier to form the supersaturated solid solution, and the ternary Al-0.4wt%Zr- 0.8wt%Cr alloy has better room and elevated temperature tensile properties than the binary Al- 0.4wt%Zr alloy. Various one-step and two-step isothermal aging cycles were investigated in order to arrive at the optimum aging schedule for the Al-0.4wt%Zr-0.8wt%Cr. It is found that soaking the alloy at 400C for 24 hours is optimum; and employing a two-step aging schedule reduces the aging time without sacrificing strength. The two- step aging schedule includes soaking the alloy at 375C for 3 hours and then at 425C for an additional 12 hours. Examination of the precipitates that form in the Al-0.4wt%Zr-0.8wt%Cr with High Resolution Transmission Electron Microscopy (HRTEM) shows that they have the L12 crystal structure. Energy Dispersive Spectrometry (EDS) shows that the particles contain only aluminum and zirconium whereas the matrix is a solid solution of chromium in aluminum. Hence, it is suggested that zirconium strengthens the Al- 0.4wt%Zr-0.8wt%Cr alloy by a precipitation hardening mechanism and chromium further enhances the strength by solid solution strengthening.
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Mjali, Kadephi Vuyolwethu. "Laser bending of commercially pure grade 2 titanium alloy plates: mechanisms analysis and characterisation of mechanical properties." Thesis, Nelson Mandela Metropolitan University, 2014. http://hdl.handle.net/10948/d1021147.
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The processing of materials has become a specialist field and the industry will continue to grow due to rising costs in labour and raw materials which has forced many automotive industry suppliers to invest heavily in this field. In order to be relevant and competitive in today’s industrial world, companies in South Africa are now forced to dedicate billions of rands in profits to research and development. Metals like titanium are finding favour with automotive and aviation companies in pursuit of savings in fuel consumption. This saving is achieved by reducing weight on aircraft and automobiles yet still meeting acceptable and improved structural integrity. In-depth research into the behaviour of various materials under varying loading conditions is therefore essential. The study on the processing of commercially pure grade 2 titanium alloy plates focuses on the development of process parameters for bending the material using a 4kW Nd: YAG laser to an approximate radius of curvature of 120mm. The resulting mechanical properties of laser formed plates are then compared to those obtained from mechanically formed samples. The titanium parent material was used to benchmark the performance of formed samples. The effect of process parameters on the mechanical properties and structural integrity also formed part of this study. To obtain the bending parameters for laser forming, various combinations of processing speeds and laser powers were used. The line energy is dependent on the power and scanning velocity parameters and these are shown in table 1. The laser power, line energy and scanning velocity were the main parameters controlled in this study and the beam diameter remained unchanged. Residual stress analysis, micro-hardness and fatigue life testing were carried out to analyse mechanical properties and the structural integrity of the plate samples. Microstructural analysis was also done to observe changes in the material as a result of the forming processes. From the results it is evident that laser forming is beneficial to the hardness of titanium but detrimental to the fatigue life at higher line energies. Residual stress analysis showed the amount of stress within the study samples increased with each forming operation. This information was vital in the analysis of the fatigue life of titanium. A fatigue life prediction model was developed from this study and it shed some light on the behaviour of titanium in fatigue testing. The model could be used to predict fatigue life when no fatigue data is available for commercially pure grade 2 titanium alloy plates. In conclusion, this study helped establish parameters that could be used to bend titanium while the analysis of mechanical properties showed the limits of working with this alloy.
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Mjali, Kadephi Vuyolwethu. "Mechanisms, analysis and characterisation of mechanical properties of laser formed commercially pure grade 2 titanium alloy plates." Thesis, Nelson Mandela Metropolitan University, 2014. http://hdl.handle.net/10948/d1021083.
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The processing of materials has become a specialist field and the industry will continue to grow due to rising costs in labour and raw materials which has forced many automotive industry suppliers to invest heavily in this field. In order to be relevant and competitive in today’s industrial world, companies in South Africa are now forced to dedicate billions of rands in profits to research and development. Metals like titanium are finding favour with automotive and aviation companies in pursuit of savings in fuel consumption. This saving is achieved by reducing weight on aircraft and automobiles yet still meeting acceptable and improved structural integrity. In-depth research into the behaviour of various materials under varying loading conditions is therefore essential. The study on the processing of commercially pure grade 2 titanium alloy plates focuses on the development of process parameters for bending the material using a 4kW Nd: YAG laser to an approximate radius of curvature of 120mm. The resulting mechanical properties of laser formed plates are then compared to those obtained from mechanically formed samples. The titanium parent material was used to benchmark the performance of formed samples. The effect of process parameters on the mechanical properties and structural integrity also formed part of this study. To obtain the bending parameters for laser forming, various combinations of processing speeds and laser powers were used. The line energy is dependent on the power and scanning velocity parameters and these are shown in table 1. The laser power, line energy and scanning velocity were the main parameters controlled in this study and the beam diameter remained unchanged. Residual stress analysis, micro-hardness and fatigue life testing were carried out to analyse mechanical properties and the structural integrity of the plate samples. Microstructural analysis was also done to observe changes in the material as a result of the forming processes. From the results it is evident that laser forming is beneficial to the hardness of titanium but detrimental to the fatigue life at higher line energies. Residual stress analysis showed the amount of stress within the study samples increased with each forming operation. This information was vital in the analysis of the fatigue life of titanium. A fatigue life prediction model was developed from this study and it shed some light on the behaviour of titanium in fatigue testing. The model could be used to predict fatigue life when no fatigue data is available for commercially pure grade 2 titanium alloy plates. In conclusion, this study helped establish parameters that could be used to bend titanium while the analysis of mechanical properties showed the limits of working with this alloy.
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Warren, Paul J. "A study of the relationship between precipitate structure and chemistry on the mechanical properties of aluminium alloys." Thesis, University of Oxford, 1993. http://ora.ox.ac.uk/objects/uuid:8259f666-f634-4127-b376-6fba8fffba28.
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The microstructural chemistry of the commercial aluminium alloy 7150, containing Al, Zn, Mg, Cu and some trace impurities, was investigated in detail. This alloy is a precipitation hardening alloy, deriving most of its strength from the fine distribution of solute rich precipitates formed during thermal processing. At peak strength this alloy suffers from the common problem of stress corrosion cracking, leading to unpredictable premature failure in the presence of a corrosive environment. Failure is mainly intergranular, thus the structure and chemistry of the grain boundary regions is of interest. A large number of previous investigations have failed to correlate any individual parameter with the stress corrosion cracking behaviour. As the analytical techniques have improved over the last three decades, more complex investigations of the microstructure and the microchemistry have been attempted, in order to more fully characterise the development of this alloy during thermal processing. This thesis presents the results of two of the highest resolution techniques available for microchemical analysis. Scanning transmission electron microscopy X-ray analysis, using a VG-HB501 dedicated scanning transmission electron microscope, enables chemical analysis with a 2nm electron probe, while atom probe analysis, using a VG-FIM100 atom probe with an additional position sensitive detector, enables single atom chemical identification with sub-nanometre spatial resolution. However, both of these techniques have their own experimental limitations which restrict the accuracy of the results obtainable. A detailed description of the many factors limiting both techniques is presented. Combining these techniques has enabled chemical analysis of all the microstructural features present in this alloy on the nanometre scale. A description of the chemical changes occurring during age hardening of this alloy is given in summary.
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Tu, Zhiqiang. "Fabrication and Mechanical Properties of Carbon Fiber Reinforced Aluminum Matrix Composites by Squeeze Casting." Thesis, Université d'Ottawa / University of Ottawa, 2020. http://hdl.handle.net/10393/40523.
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Rapid modern technological changes and improvements bring great motivations in advanced material designs and fabrications. In this context, metal matrix composites, as an emerging material category, have undergone great developments over the past 50 years. Their primary applications, such as automotive, aerospace and military industries, require materials with increasingly strict specifications, especially high stiffness, lightweight and superior strength. For these advanced applications, carbon fiber reinforced aluminum matrix composites have proven their enormous potential where outstanding machinability, engineering reliability and economy efficiency are vital priorities.
To contribute in the understanding and development of carbon fiber reinforced aluminum matrix composites, this study focuses on composite fabrication, mechanical testing and physical property modelling. The composites are fabricated by squeeze casting. Plain weave carbon fiber (AS4 Hexcel) is used as reinforcement, while aluminum alloy 6061 is used as matrix. The improvement of the squeeze casting fabrication process is focused on reducing leakage while combining thermal expansion pressure with post-processing pressing. Three different fiber volume fractions are investigated to achieve optimum mechanical properties. Piston-on-ring (POR) bend tests are used to measure the biaxial flexural stiffness and fracture strength on disc samples. The stress-strain curves and fracture surfaces reveal the effect of fiber-matrix interface bonding on composite bend behaviour. The composites achieved up to 11.6%, 248.3% and 90.1% increase in flexural modulus, strain hardening modulus and yield strength as compared with the unreinforced aluminum alloy control group, respectively. Analytical modelling and finite element modelling are used to comparatively characterise and verify the composite effective flexural modulus and strength. Specifically, they allowed
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evaluating how far the experimental results deviate from idealized assumptions of the models, which provides an insight into the composite sample quality, particularly at fiber-matrix interfaces. Overall, the models agree well with experimental results in identifying an improvement in flexural modulus up to a carbon fiber volume fraction of 4.81vol%. However, beyond a fiber content of 3.74vol%, there is risk of deterioration of mechanical properties, particularly the strength. This is because higher carbon fiber volume fractions restrict the infiltration and wetting of carbon fibre by the liquid, potentially leading to poor fiber-matrix interface bonding. It is shown that higher thermal expansion pressures and subsequent post-processing pressing can overcome this challenge at higher carbon fiber volume contents by reducing fiber-aluminum contact angle, improving infiltration, reducing defects such as porosity, and overall improving fiber-matrix bonding.
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Jurak, Sarah F. "Statistical analysis of the mechanical properties of Friction Stir Welded AA2024 and AA2198 aluminum alloys." Thesis, Wichita State University, 2011. http://hdl.handle.net/10057/5181.
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This thesis presents an analysis of data based on the results of a previous study into the
path independence of friction stir welding (FSW). The original study was conducted in two
phases using AA2024 and AA2198 aluminum alloy material. In Phase I, welds were made with
six different tool designs, and tensile data was entered into Statgraphics® software as part of a
design of experiments (DOE) approach for the purpose of optimizing the weld parameter process
windows for each tool design. Phase II included a round robin study where welds were produced
at four sites to evaluate site-to-site variability. In the present study, testing of the welds included
additional tensile testing, full-field microhardness testing, and conductivity testing of the welds
produced in the prior two phases of the program. The welds were inspected for defects, and the
method of failure on the tensile specimens is discussed. Tensile data was evaluated statistically
using Statgraphics® software. Previously, as part of Phase I, that data was evaluated using the
techniques of chapter nine of the Metallic Materials Properties Development and Standardization
(MMPDS), and design allowables were calculated at that time. In the present study, Phase II
data was compared using the design allowables from Phase I.
Variability was not found to be significant when evaluated according to location of the
tensile coupon along the weld joint line or as a function of weld parameters in the process
window. Although site-to-site variability was significant, it was low, with the highest variation
for each material being 2 to 5.5 ksi. No significant outliers were identified.
There is evidence that the friction stir welding process is path-independent and that a
defect-free weld is uniform in tensile strength from beginning to end. There is also evidence that
a DOE approach can be used to optimize the weld parameter process window for any tool in
order to identify a range of weld parameters where a defect-free weld can be produced.Thesis (M.S.)--Wichita State University, College of Engineering, Dept. of Mechanical Engineering.
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Seifeddine, Salem. "Characteristics of cast aluminium-silicon alloys : microstructures and mechanical properties /." Linköping : Univ, 2006. http://www.bibl.liu.se/liupubl/disp/disp2006/tek1058s.pdf.
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El-Sayed, Mahmoud Ahmed Mahmoud. "Double oxide film defects and mechanical properties in aluminium alloys." Thesis, University of Birmingham, 2012. http://etheses.bham.ac.uk//id/eprint/3924/.
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Double oxide films (bifilms) are significant defects in light alloy castings which were reported to have detrimental effects on the reliability of the castings. The research reported here was aimed at studying how these defects develop with time. The results suggested that both O and N inside the bifilm would be consumed by reaction with the surrounding melt, and that H might be diffused into the defect. Based on the estimated reactions rates the time required for the consumption of the atmosphere inside a bifilm entrained in pure Al, Al-7wt.%Si-0.3wt.%Mg and Al-5wt.%Mg alloy melts, was determined to be 538, 1509 and 345 seconds respectively. The results also suggested the occurrence of two competing mechanisms during holding of the castings in the liquid state before solidification. The first mechanism was related to the consumption of the bifilm atmosphere, which might reduce the size of bifilms and therefore increase the Weibull moduli the UTS and the % elongation. The other mechanism was the diffusion of H into the bifilms, which would be expected to increase their sizes and reduce the moduli. This research therefore could lead to the development of new techniques by which bifilms might be deactivation in light alloy castings.
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Kerry, S. "Microstructure and mechanical properties of high strength cast aluminium alloys." Thesis, University of Bath, 1987. https://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.376328.
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Williams, Cory R. "The Effects of Scandium and Zirconium Additions on Aluminum Mechanical Properties, Post-Braze Grain Structure, and Extrusion." Ohio University / OhioLINK, 2012. http://rave.ohiolink.edu/etdc/view?acc_num=ohiou1331521298.
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Ozdes, Huseyin. "The Relationship Between High-Cycle Fatigue and Tensile Properties in Cast Aluminum Alloys." UNF Digital Commons, 2016. http://digitalcommons.unf.edu/etd/716.
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Cast aluminum alloys are common in automotive and aerospace applications due to their high strength-to-density ratio. Fracture data for cast aluminum alloys, such as fatigue life, tensile strength and elongation, are heavily affected by the structural defects, such as pores and bifilms. There have been numerous studies in which either fatigue performance or tensile deformation were characterized and linked to casting defects. However, a comprehensive study that correlates tensile and fatigue properties has not been reported. The present study is motivated to fill this gap. The main objective of the investigation is to analyze the link between tensile and fatigue performance of commonly used cast aluminum alloys, and determine whether fatigue performance of cast aluminum alloys can be predicted. To accomplish this task, four research questions were developed: (i) how well do equations developed to account for mean stress effects perform in cast aluminum alloys, especially in datasets with various levels of structural quality, (ii) is the strong correlation between fatigue life and structural quality index obtained from tensile data reported for A206 alloy castings applicable to other aerospace and automotive casting alloys, (iii) how do methods to estimate high cycle fatigue from tensile data perform with aluminum castings, and (iv) can the axial fatigue performance of an A356-T6 casting be predicted from rotating beam fatigue data. Among the three mean stress correction models analyzed by using seven datasets from the literature, the one developed by Walker with an adjustable exponent has provided the best fit. It has been hypothesized that the adjustable Walker parameter is related to the structural quality index, QT, estimated from tensile data. Results have shown that there is indeed a strong correlation between QT and the Walker parameter. Moreover the parameters of the xvi Weibull distribution estimated from corrected data have been found to be strongly influenced by the mean stress correction method used. Tensile and fatigue life data for 319, D357 and B201 aluminum alloy castings reported in the literature have been reanalyzed by using a maximum likelihood method to estimate Basquin parameters in datasets with run-outs, Weibull statistics for censored data and mean stress correction. After converting tensile data to QT, a distinct relationship has been observed between the expected fatigue life and mean quality index for all alloys. Moreover, probability of survival in fatigue life has been found to be directly linked to the proportions of the quality index distributions in two different regions, providing further evidence about the strong relationship between elongation, i.e., structural quality, and fatigue performance [1]. Specimen geometry has been found to make the largest difference whereas the two aerospace alloys, B201 and D357, with distinctly different microstructures, have followed the same relationship, reinforcing the findings in the literature that fatigue life in aluminum castings is mainly determined by the size distribution and number density of structural defects. Six methods to predict fatigue life from tensile data have been compared by using data from the literature as well as the experimental A356 data developed in this study. Results have shown that none of the six methods provide reliable results. The consistently poor performance of the methods developed for steels and wrought alloys can be attributed to the major structural defects, namely bifilms, in aluminum castings. A new method to estimate the S-N curve from tensile data have been developed by using data for seventy-one S-N curves have been collected and Basquin parameters have been determined. Analysis showed that there is a strong relationship between QT and the Basquin exponent. xvii The Basquin parameters estimated by using the empirical relationships developed in the present study have provided better fits to the same datasets tested for the six methods. Hence the model developed in this study is proposed as the most reliable method to estimate high cycle fatigue properties. Finally, three methods to convert rotating bending fatigue test results to uniaxial fatigue data have been investigated by using the data developed in this study. Results have indicated that the method developed by Esin, in which both the fatigue life and alternating stress are corrected, provide the best estimate. Analyses of fracture surfaces of broken specimens via scanning electron microscopy have shown that tensile, axial fatigue and rotating beam fatigue properties are all strongly influenced by the same structural defects, confirming the validity of the approach taken in this study.
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Ma, Shuhui. "A methodology to predict the effects of quench rates on mechanical properties of cast aluminum alloys." Link to electronic dissertation, 2006. http://www.wpi.edu/Pubs/ETD/Available/etd-050106-174639/.
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Dissertation (Ph.D.)--Worcester Polytechnic Institute.Keywords: Time-Temperature-Property curve, Jominy End Quench, ANOVA analysis. Quench Factor Analysis, Taguchi design, Polymer quench, Cast Al-Si-Mg alloys, Quenching, Heat treatment. Includes bibliographical references (p.115-117).
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O'Rourke, Jane. "Microstructure and mechanical properties of fibre-reinforced heat-treatable aluminium alloys." Thesis, University of Bath, 1995. https://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.261348.
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Zander, Johan. "Modelling mechanical properties by analysing datasets of commercial alloys." Licentiate thesis, Stockholm : Industriell teknik och management, Kungliga Tekniska högskolan, 2007. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-4527.
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Hwang, Junyeon. "Characterization and Mechanical Properties of Nanoscale Precipitates in Modified Al-Si-Cu Alloys Using Transmission Electron Microscopy and 3D Atom Probe Tomography." Thesis, University of North Texas, 2007. https://digital.library.unt.edu/ark:/67531/metadc3661/.
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Among the commercial aluminum alloys, aluminum 319 (Al-7wt%Si-4wt%Cu) type alloys are popularly used in automobile engine parts. These alloys have good casting characteristics and excellent mechanical properties resulting from a suitable heat treatment. To get a high strength in the 319 type alloys, grain refining, reducing the porosity, solid solution hardening, and precipitation hardening are preferred. All experimental variables such as solidification condition, composition, and heat treatment are influence on the precipitation behavior; however, precipitation hardening is the most significant because excess alloying elements from supersaturated solid solution form fine particles which act as obstacles to dislocation movement. The challenges of the 319 type alloys arise due to small size of precipitate and complex aging response caused by multi components. It is important to determine the chemical composition, crystal structure, and orientation relationship as well as precipitate morphology in order to understand the precipitation behavior and strengthening mechanism. In this study, the mechanical properties and microstructure were investigated using transmission electron microscopy and three dimensional atom probe tomography. The Mn and Mg effects on the microstructure and mechanical properties are discussed with crystallographic study on the iron intermetallic phases. The microstructural evolution and nucleation study on the precipitates in the low-Si 319 type aluminum alloys are also presented with sample preparation and analysis condition of TEM and 3DAP tomography.
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Afshari, Davood. "Mechanical Properties of Resistance Spot Welds in Lightweight Applications." Licentiate thesis, KTH, Lättkonstruktioner, 2013. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-131306.
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This licentiate thesis is concerned with residual stresses in aluminum alloy 6061-T6 resistance spot welded joint. Several topics related to mechanical strength of welded structures are treated such as; nugget size and microhardness and microstructures of weld zone and their influence on mechanical strength of welded structure, failure load measurement using tensile-shear test, resistance spot welding simulation, residual stress measurement by X-ray diffraction method and analysis effect of welding parameters on the mechanical strength and the residual stresses. To investigate the effect of resistance spot weld parameters on mechanical strength of welded structures, various welding parameters e.g. welding current, welding time and electrode force are selected to produce welded joints with different quality. According to the failure mode, the empirical equation was used to prediction of failure load base on nugget size and hardness of failure line. Microstructure study has been carried out to investigate microstructural changes in the welded joints. Microhardness tests are done to find hardness profiles due to microstructural changes and determine the minimum hardness. In addition, an electro-thermal-structural coupled finite element model and X-ray diffraction residual stress measurement have been utilized to analyze residual stresses distribution in weld zone. The electrical and thermal contact conductance, as mandatory factors are applied in contact area between electrode-workpiece and workpiece-workpiece to resolve the complexity of the finite element model. The physical and mechanical properties of the material are defined as thermal-dependent in order to improve the accuracy of the model. Furthermore, the electrodes are removed after holding cycle using the birth and death elements method. Moreover, the effect of welding parameters on maximum residual stress is investigated and a regression model is proposed to predict maximum tensile residual stresses in terms of welding parameters. The results obtained from the finite element analysis have been used to build up two back-propagation artificial neural network models for the residual stresses and the nugget size prediction. The results revealed that the neural network models created in this study can accurately predict the nugget size and the residual stresses produced in resistance spot weld. Using a combination of these two developed models, the nugget size and the residual stresses can be predicted in terms of spot weld parameters with high speed and accuracy.QC 20131014
No
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Brosi, Justin Keith. "Mechanical Property Evolution of Al-Mg Alloys Following Intermediate Temperature Thermal Exposure." Cleveland, Ohio : Case Western Reserve University, 2010. http://rave.ohiolink.edu/etdc/view?acc_num=case1270163761.
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Thesis (Master of Sciences (Engineering))--Case Western Reserve University, 2010Department of Materials Science and Engineering Title from PDF (viewed on 2010-05-25) Includes abstract Includes bibliographical references and appendices Available online via the OhioLINK ETD Center
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Sawalha, Kameel. "The fatigue properties of pressure diecast zinc-aluminium based alloys." Thesis, Aston University, 1991. http://publications.aston.ac.uk/11933/.
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The fatigue behaviour of the cold chamber pressure-die-cast alloys: Mazak3, ZA8, ZA27, M3K, ZA8K, ZA27K, K1, K2 and K3 was investigated at temperature of 20oC. The alloys M3K, ZA8K and ZA27K were also examined at temperatures of 50 and 100oC. The ratio between fatigue strength and tensile strength was established at 20oC at 107 cycles. The fatigue life prediction of the alloys M3K, ZA8K and ZA27K was formulated at 20, 50 and 100oC. The prediction formulae were found to be reasonably accurate. All of the experimental alloys were heterogeneous and contained large but varying amounts of pores. These pores were a major contribution and dominated the alloys fatigue failure. Their effect, however, on tensile failure was negligible. The ZA27K possessed the highest tensile strength but the lowest fatigue strength. The relationship between the fracture topography and the microstructure was also determined by the use of a mixed signal of a secondary electron and a back-scattered electron on the SEM. The tensile strength of the experimental alloys was directly proportional to the aluminium content within the alloys. The effect of copper content was also investigated within the alloys K1, K2, ZA8K and K3 which contained 0%, 0.5%, 1.0% and 2.0% respectively. It was determined that the fatigue and tensile strengths improved with higher copper contents. Upon ageing the alloys Mazak3, ZA8 and ZA27 at an ambient temperature for 5 years, copper was also found to influence and maintain the metastable Zn-Al ('_m) phase. The copper free Mazak3 upon ageing lost this metastable phase. The 1.0% copper ZA8 alloy had lost almost 50% of its metastable phase. Finally the 2.0% copper ZA27 had merely lost 10% of its metastable phase. The cph zinc contained a limited number of slip systems, therefore twinning deformation was unavoidable in both fatigue and tensile testing.
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Payandeh, Mostafa. "Rheocasting of Aluminium Alloys : Slurry Formation, Microstructure, and Properties." Licentiate thesis, Tekniska Högskolan, Högskolan i Jönköping, JTH. Forskningsmiljö Material och tillverkning – Gjutning, 2015. http://urn.kb.se/resolve?urn=urn:nbn:se:hj:diva-26297.
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Innovative materials with novel properties are in great demand for use in the criticalcomponents of emerging technologies, which promise to be more cost-effective and energyefficient.A controversial issue with regard to manufacturing complex industrial products isto develop advanced materials with optimised manufacturability in addition to the requiredmechanical and physical properties. The objective of this research study was to develop andoffer new solutions in material-processing-related issues in the field of mechanical andelectrical engineering. This was achieved by investigating the new opportunities affordedby a recently developed rheocasting method, RheoMetalTM process, with the goal of comingto an understanding of the critical factors for effective manufacturing process. A study of the evolution of microstructure at different stages of the rheocasting process,demonstrated the influence of multistage solidification on the microstructural characteristicsof the rheocast components. The microstructural investigation onquench slurry showed itconsists of the solute-lean coarse globular α-Al particles with uniform distribution ofalloying elements, suspended in the solute-rich liquid matrix. Such inhomogeneous slurryin the sleeve seems to play a critical role in the inhomogeneity of final microstructure. Inthe rheocast component, the separation of the liquid and solid parts of slurry during fillinginfluenced on the microstructural inhomogeneity. The relationship between the microstructural characteristics and properties of the rheocastcomponents was investigated. The study on the fracture surfaces of the tensile-testedspecimens showed that the mechanical properties strongly affected by microstructuralinhomogeneity, in particular macrosegregation in the form of near surface liquid segregationbands and subsurface porosity. The thermal conductivity measurement showed variation ofthis property throughout the rheocast component due to variations in the ratio of solute-leanglobular α-Al particles and fine solute α-Al particles. The result showed silicon in solidsolution have a strong influence (negative) on thermal conductivity and precipitation ofsilicon by heat treatment process increase the thermal conductivity.RheoCom
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Coruh, Ali. "Molecular-dynamics Investigation Of The Dynamic Properties Of Pd And Al Metals, And Their Alloys." Phd thesis, METU, 2003. http://etd.lib.metu.edu.tr/upload/12604716/index.pdf.
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The dynamic properties of Palladium (Pd) and Aluminum (Al) metals and their alloys are investigated by means of Molecular Dynamics using the Quantum Sutton-Chen force field in five different concentrations. Calculations have been carried out for liquid structures. Although this study is done for liquid structures, basic solid state properties are also investigated to prove the validity of potential parameters. Results are compared with each other and with experimental, theoretical and simulated results. Liquid state transferability of Quantum Sutton-Chen parameters have been investigated and discussed. High temperature properties, which are not easy to work experimentally, are simulated and high temperature behavior of Pd-Al alloy is investigated.
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Toschi, Stefania <1986>. "Cast Aluminum Alloys and Al-Based Nanocomposites with Enhanced Mechanical Properties at Room and High Temperature: Production and Characterization." Doctoral thesis, Alma Mater Studiorum - Università di Bologna, 2016. http://amsdottorato.unibo.it/7495/.
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The present PhD thesis summarizes the results of experimental activities carried out on the production and characterization of cast aluminum alloys and Al-based nanocomposites for room and high temperature applications. Two quaternary Al-Si-Cu-Mg alloys (A354 and C355) were studied, aiming to investigate the effect of chemical composition, solidification rate and heat treatment condition on the tensile and fatigue behavior at room and high temperature. Heat treatment optimization of A354 alloy was carried out. The overaging behavior of A354 and C355 alloys was compared to that of A356 (Al-Si-Mg) alloy, in order to evaluate the thermal stability of the alloys. As a result, the concurrent presence of Cu and Mg confers, by precipitation hardening, enhanced mechanical properties and higher thermal stability in comparison to the traditional Al-Si-Mg alloy. A preliminary study aimed to evaluate the effect of Molybdenum addition on A354 overaging response was also carried out. Enhanced mechanical properties after long-term overaging were registered in A354-0.3wt.%Mo alloy, in comparison to the base A354. Casting techniques for the production of Al-matrix composites were implemented at the laboratory scale. The stir-casting method assisted with ultrasonic treatment and in situ reactive casting were applied to produce Al2O3-A356 micro/nanocomposites and ZrB2-A356 composites, respectively. Friction Stir Process (FSP) was evaluated as possible solid state processing route to: (i) enhance Al2O3 nanoparticles distribution in a semisolid processed AA2024-based nanocomposite, and (ii) directly distribute Al2O3 nanoparticles into AA7075 alloy at the solid state. Experimental results highlighted difficulties in obtaining an even distribution of nanoparticles, by both liquid and semi-soli state routes, due to the low wettability of nano-sized ceramic reinforcement. The application of FSP led to enhanced nanoparticles distribution, mitigation of casting defects associated to nanoparticles addition (porosity, nanoparticles clusters) and microstructural homogenization, thus allowing to better exploit nanoparticles strengthening effect.
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Stein, Julien. "AA5083 aluminium alloys reinforced with multi-walled carbon nanotubes : microstructure and mechanical properties." Thesis, Montpellier 2, 2012. http://www.theses.fr/2012MON20002.
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Cette étude a pour but de développer de nouveaux matériaux composites à matrice métallique renforcés par des nanotubes de carbone (CNT) et présentant des propriétés mécaniques améliorées. La majeure partie de ce travail a été réalisée en utilisant des CNT multi-feuillets synthétisés par déposition chimique en phase vapeur en tant que renforts et un alliage d'aluminium AA5083 comme matrice. Des composites CNT/AA5083 denses et homogènes ont été élaborés par le procédé de métallurgie des poudres suivi par une étape de mise en forme, l'extrusion. L'homogénéité de la dispersion des CNT à l'échelle microscopique dans les composites s'avère être un paramètre clé pour l'amélioration des propriétés mécaniques. Ceci a été réalisé par broyage planétaire à haute énergie impliquant des mécanismes de déformation plastique et de soudure à froid et a été démontré à l'aide d'études cartographiques par spectroscopie Raman. La limite d'élasticité, la résistance à la traction et la micro-dureté des composites homogènes ont été augmentées jusqu'à respectivement 55%, 61% et 33% en comparaison avec l'alliage sans CNT et préparé dans les mêmes conditions. Le coefficient de dilatation thermique a été quant à lui réduit de 10%. Les propriétés optimales ont été obtenues pour des concentrations en CNT de 1,5 % en masse. Le renforcement du matériau a été principalement attribué au transfert de charge à l'interface CNT/matriceThe overall goal of this thesis is to process new metal matrix composites reinforced by CNT with enhanced mechanical properties. The main part of this work was achieved using CVD-grown multi-walled CNT as reinforcement and a high-performance light aluminium alloy, AA5083, as the matrix. Dense and homogeneous CNT/AA5083 composites were processed by the powder metallurgy route, followed by an extrusion forming process. A homogeneous dispersion of the CNT in the composites at the micron scale appears to be a key parameter for improving the mechanical properties. This could be achieved using high energy ball milling through the mechanisms of plastic deformation and cold-welding, and was demonstrated from Raman spectroscopy cartography studies. Yield strength, ultimate tensile strength and micro-hardness of the homogeneous composites were increased by up to 55%, 61% and 33%, with respect to raw alloys processed in the same conditions, and the coefficient of thermal expansion was decreased by 10%. Optimal results were obtained with a CNT con-tent of 1.5 wt.-%. The material strengthening was principally attributed to load transfer at the CNT/matrix interface
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Lindrud, Lennart, and Göran Lindgren. "The influence of Mn on the microstructure and mechanical properties of Al-Si based alloys containing Fe." Thesis, Jönköping University, JTH, Mechanical Engineering, 2006. http://urn.kb.se/resolve?urn=urn:nbn:se:hj:diva-377.
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Abstract
The purpose of this research is to investigate the influence of Manganese (Mn) on cast aluminum alloys where a substantial amount of Iron (Fe) is included. Ductility and tensile strength need to be improved in recycled aluminum alloys where greater amounts of Fe are found. Fe is a common impurity and is known to be detrimental to mechanical properties and in order to neutralize the effects of Fe; modifiers such as Mn are added. In this investigation, attempts will be carried out aiming to find the optimal amount of Mn. Other related topics that will be discussed are whether there exists a Mn/Fe ratio which clearly modifies the harmful iron- rich phases and improves the properties for a certain alloy or not. Also, will the heat treatment have a significant effect on mechanical properties? These are some of the questions that will be answered in this paper.
It is hard to find research articles that focus only on the influence of Mn on the microstructure and mechanical properties of Al-Si cast alloys. Much of the work that is already published concerns only a specific alloy and casting method. In this work three different casting processes, sand-, die- and high pressure die-casting, will be simulated by using gradient solidification equipment. Furthermore, the influence of heat treatment on the mechanical properties will be examined.
The results showed that the solidification rate had the biggest impact on the microstructure and mechanical properties of the alloys, where the fastest cooling rate gave the best results. The effect of Mn seems to influence the samples with coarser microstructures significantly where it had time to modify the Iron-rich needles, also called the β-phase. At higher cooling rates the impact of Mn was impeded. It has been observed that a high content of Mn (around 0.6%) needs to be added before the properties start to improve. UTS (Ultimate Tensile Strength) and YS (Yield Strength) are improved while ductility is lowered. Heat treatment did not seem to have any influence on the effects of Mn.
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Mir, Arshad A. "The creep properties of a series of zinc-rich zinc-aluminium alloys." Thesis, Aston University, 1998. http://publications.aston.ac.uk/13277/.
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The compressive creep behaviour of six sand cast zinc-rich alloys: No3 and No5, corresponding to BS 1004A and BS 1004B, respectively, alloy No2, ILZRO,.16 and two newer alloys ACuZinc5 and ACuZinc10 was investigated. The total creep contraction of the alloys was found to be well correlated using an empirical equation. On the basis of this equation, a parametrical relationship was derived which allowed the total creep contraction to be related to the applied stress, the temperature and the time of test, so that a quantitative assessment of compressive creep of the alloys could be made under different testing conditions. The primary creep and secondary creep rates were found for the alloys at different temperatures and stresses. Generally, the primary creep contraction was found to increase with copper content, whereas secondary creep rates decreased in the order No3, ACuZinc10, ACuZinc5 and No2. ILZRO.16 was tested only at the highest stress and two higher temperatures. The results showed that ILZRO.16 had higher creep resistance than all the other alloys. Thus, based on the above empirical equation, alloy No2 was found to have a substantially better total creep resistance than alloys No3 and No5, and slightly better than ACuZinc5 and ACuZinc10 for strains up to 1%. Both ACuZinc alloys had higher creep strength than commercial alloys No3 and No5. Alloy No5 had much higher creep resistance than alloy No3 under all conditions. The superior creep resistance of alloy No2 was considered to be due to the presence of small precipitates of -phase in the zinc matrix and a regular eutectic morphology. The stress exponents and activation energies for creep under different testing conditions were found to be consistent with some established creep-controlling mechanisms; i.e. dislocation climb for alloy No3, dislocation climb over second phase particles for alloys No5, No2, ACuZinc10, controlled by lattice diffusion in the zinc-rich phase. The lower creep resistance of alloy No3 was mainly due to the lower creep strength of copper-free primary particles having greater volume than eutectic in the microstructure. Alloys No5, ACuZinc5 and ACuZinc10 showed much better creep resistance than alloy No3, based on the precipitation-hardening due to the presence of small -phase precipitates. The primary dendrites in both ACuZinc alloys however were not of much benefit in improving the creep resistance of the alloys.
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Watson, Douglas. "Microstructure and mechanical properties of ductile die-cast Al-Mg-Si-Mn alloys." Thesis, Brunel University, 2015. http://bura.brunel.ac.uk/handle/2438/12874.
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Aluminium alloys have been seen a dramatic increase in transport manufacturing in past two decades. This is primarily driven by the achievement of effective weight-savings, increased vehicle fuel efficiency and reduced CO2 emissions in transport. One of the significant progresses in most recent years has been in the application of aluminium-intensive car body structure, in which the manufacturing of thin wall castings with improved ductility is one of the critical issues. High pressure die casting (HPDC) is a fast and economical near-net shape manufacturing method to produce thin wall components. Therefore the application of HPDC process to make thin wall structural components for aluminium-intensive car body structure is one of the most challenges in recent development. However, the currently available die cast aluminium alloys are unable to fulfil this requirement because of the insufficient ductility, which is essential for joining castings with sheets and extruded parts. This has become critical in further development and extensive acceptance in car manufacturing industry. Generally, the mechanical properties of die castings are determined by alloy composition, defect levels and microstructure in the castings. In the present study, the significant achievement is the development of Al-Mg-Si-Mn alloy for HPDC process to provide improved ductility in die castings in order to satisfy the requirement of mechanical properties, in particular ductility for the application in automotive body structure. Starting from the thermodynamic analysis and CALPHAD (Computer Coupling of Phase Diagrams and Thermochemistry) modelling of Al-Mg-Si system for solidification and phase formation, the alloy composition was optimised using international standard tensile samples to review the effect of various alloying elements on the mechanical properties. Another achievement is the understanding of the solidification and microstructural evolution, the relationship between the microstructure and mechanical properties, and the strengthening mechanisms in the developed alloy. The solidification behaviour in the shot sleeve and in the die cavity was examined for the formation of the primary α-Al phase, eutectic Al-Mg2Si phases in the alloy. The morphology, size and size distribution of the primary α-Al phase were characterised under different solidification conditions. The growth morphology of the primary α-Al phase formed in the shot sleeve and in the die cavity was analysed using the Mullins-Sekerka instability theory and the growth rate of eutectic Al-Mg2Si phases during solidification was calculated using Jackson-Hunt theory. Still another achievement is the study of the effect of Mn and Fe on the morphology, size and distribution of various Fe-rich compounds in the Al-Mg-Si alloy produced by HPDC process. The assessment was associated with the mechanical properties of yield strength, ultimate tensile strength and elongation with different Fe and Mn contents. CALPHAD modelling of multi-component Al-Mg-Si-Mn-Fe and Al-Mg-Si-Fe systems was studied to find out the effect of Fe impurity in the Al-Mg-Si alloy. The precise accumulation of iron during HPDC using fully recycled materials was examined to predict the maximum cycles to produce castings with required mechanical properties. The strengthening mechanism and the relationship between the microstructure and mechanical properties are explored in the alloy made by secondary materials. Furthermore, the effect of nickel on the microstructure and mechanical properties of the die-cast Al-Mg-Si-Mn alloy was also studied in association with the formation of Ni-rich intermetallics during solidification in the die-cast Al-Mg-Si-Mn alloy containing different Ni contents. The final achievement is the understanding of the repeatability of die castings made by the new alloy with industrial scale components. The tensile properties of standard samples that were obtained directly from HPDC process and made by the machined die castings at different locations were further assessed for the reproducibility of casting components made by the Al-Mg-Si-Mn alloy. The distributions of yield strength, ultimate tensile strength and elongation of the tensile samples were analysed by the average values with standard deviations and by the Weibull statistical model with three parameters. The correlations between the mechanical properties and the microstructural features, porosity levels and fracture morphology were investigated for the different types of samples. It was found that three-parameter Weibull analysis was capable of analysing the reproducibility of die cast components and the scattering of tensile properties was mainly due to the presence of porosity and non-uniform microstructure in the die-castings.
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Tan, Evren. "The Effect Of Hot-deformation On Mechanical Properties And Age Hardening Characteristics Of Al-mg-si Based Wrought Aluminum Alloys." Master's thesis, METU, 2006. http://etd.lib.metu.edu.tr/upload/12607937/index.pdf.
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Microstructural and mechanical characterizations of heat treatable Al-Mg-Si-Cu based wrought aluminum alloys have been studied. The aim of this work was to produce fine grained, high strength alloy by adjusting processing conditions: deformation, solutionizing and aging.
First, primary characterization was carried out via SEM-EDS analyses and tensile tests. Then an extensive experimental study has been carried out on two sets of samples. The first set has been studied to determine the ideal conditions for solutionizing and aging processes by analyzing the variation of hardness with different solutionizing and aging time and temperature. The second set, have first been mechanically deformed by swaging at four different deformations and four different temperatures, then heat treated. The hardness measurements have been carried out before and after solutionizing and also after aging. Finally, recrystallization behavior has been investigated by measuring grain size before and after solutionizing treatment using image analyzer software.
The initial characterizations showed that Mg2Si and complex iron, manganese bearing intermetallics were the primary particles observed in the α
-Al matrix. Nearly 140HB hardness could be obtained with solutionizing at 530°
C and aging at 175°
C for 8 hours which was determined as the optimum treatment for obtaining peak hardness. When shaping (deformation) was concerned
strength loss was the overall outcome of any hot or cold deformation before solutionizing
which was most probably due to the destruction of the initial microstructure. Improvement in the percent elongation was the promising aspect of this application. Strength loss was increased for samples deformed at higher temperatures and higher reductions.
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Alfaro, Mercado Ulises [Verfasser]. "Microstructure, mechanical behavior and corrosion properties of friction stir welded aluminum alloys used in the aerospace industry / Ulises Alfaro Mercado." Aachen : Hochschulbibliothek der Rheinisch-Westfälischen Technischen Hochschule Aachen, 2012. http://d-nb.info/1022088807/34.
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Sofyan, Nofrijon Bin Imam Gale W. F. "Microstructure and mechanical properties of 2024-T3 and 7075-T6 aluminum alloys and austenitic stainless steel 304 after being exposed to hydrogen peroxide." Auburn, Ala, 2008. http://repo.lib.auburn.edu/EtdRoot/2008/SUMMER/Materials_Engineering/Dissertation/Sofyan_Nofrijon_36.pdf.
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Syahril. "Effect of ternary additions and thermomechanical treatments on the properties of Fe-11wt% Al alloys." Thesis, Imperial College London, 2000. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.325578.
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Zhu, Baiwei. "On the influence of Si on anodising and mechanical properties of cast aluminium alloys." Licentiate thesis, Tekniska Högskolan, Högskolan i Jönköping, JTH, Material och tillverkning, 2017. http://urn.kb.se/resolve?urn=urn:nbn:se:hj:diva-35096.
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The combination of two cost-effective processes, i.e. casting and anodising, would be an interest for the aluminium component applications. However, there are some obstacles in the application of anodising on cast Al alloys. The challenges mostly relate to the alloying elements especially Si and the surface quality. With the development of casting process, cast aluminium alloys with low Si content can be casted, and a complex geometry component with reasonably good surface finish can be achieved. This study aims to identify the influence of Si on anodising and mechanical properties of Al-Si alloys. In this study, six Al-Si alloys with three different Si level and two different Sr level were investigated. Sr acts as a modifier to change the morphology of Si particles. The directional solidification technology was used to vary the microstructure coarseness by controlling the cooling rate to study the influence of Si level, Si particle morphology and cooling rate on mechanical properties, oxide layer formation and corrosion protection performance in cast Al-Si alloys. This study has observed that Si has a significant influence on anodising. During anodising, Si particles are anodised at a lower rate than the Al phase. The presence of Si particles in eutectic phase make the oxide layer locally thinner and more defected due to the low oxide growth rate in eutectic phase. This study observed the presence of residual metallic Al phase beneath or between Si particles. Due to their presence and their geometry, Al can be shielded by Si particles and prevented from oxidation. Si particles also act as a key role in the corrosion protection of oxide layer in Al-Si alloys. The corrosion attack propagates along Si particles as well as oxide defects to the Al substrate. It is found that the morphology of Si particles has a significant influence on the oxide layer formation and corrosion protection performance of the oxide layer on cast Al-Si alloys. A substantially improvement the corrosion resistance of anodised layer on Al-Si alloys is attributed to the morphology change from interconnected flakes to disconnected Si fibres when Sr is added, with less oxide defects and better oxide distribution. The Si level governs the mechanical properties of Al-Si based alloys. An increase of Si content in Al alloys improves the mechanical properties such as ultimate tensile and yield strength as well as hardness of the materials, but decreases the ductility. However, an increase of Si level in Al alloys decreases the thickness of oxide layer, and thereby, the corrosion protection of the oxide layer is deteriorated.Kombinationen av två kostnadseffektiva processer, gjutning och anodisering, är av intresse för tillämpning på aluminiumkomponenter. Det finns dock hinder för tillämpning av anodisering på gjutna aluminiumlegeringar. Utmaningarna relaterar till effekten av legeringselement, i synnerhet Si, och komponentens ytkvalité. Med utvecklingen av gjutprocesser kan aluminiumlegeringar med lågt Si-innehåll gjutas, och komponenter med komplex geometri med förbättrad ytkvalité kan uppnås. Denna studie syftar till att identifiera påverkan av Si på anodisering och mekaniska egenskaper hos Al-Si-baserade legeringar. I denna studie undersöktes sex Al-Si-legeringar med tre nivåer av Si och två nivåer av Sr. Tillsatser av Sr leder till modifikation av morfologin hos Si-partiklar. Med hjälp av tekniken ”riktad stelning” varierades stelningshastigheten för att studera sambanden mellan halten och morfologin av Si, mikrostrukturens grovlek och dess inverkan på mekaniska egenskaper, samt oxidskiktets bildning och korrosionsbeständighet hos gjutna Al-Si-legeringar. Denna studie visar att Si har ett betydande inflytande på anodisering r. Under anodisering, anodiseras Si-partiklar i en lägre takt än Al-fasen. Närvaron av Si-partiklar i eutektisk fas bidrar till ett lokalt förtunnat oxidskikt med fler defekter på grund av den låga oxidtillväxthastigheten i eutektisk fas. Denna studie observerade förekomsten av kvarvarande metalliska Al fasen under eller mellan Si-partiklar. På grund av Si-partiklarnas närvaro och geometri, kan Al skärmas från oxidation. Si-partiklar har även en nyckelroll i korrosionsskydd av oxidskiktet i Al-Si-legeringar. Korrosionsangreppet propagerar längs Si-partiklar samt oxiddefekter till Al-substrat. Morfologin av Si-partiklar har funnits ha en betydande inverkan på oxidskiktets bildning och korrosionsskydd hos gjutna Al-Si-legeringar. En väsentlig förbättring av korrosionsbeständigheten i anodiserat skikt hos Al-Si-legeringar tillskrivs förändring av kiselns morfologi från sammankopplade flingor till osammanhängande fibrer när Sr tillsätts, med mindre oxiddefekter och bättre fördelning av oxid. Si halten påverkar de mekaniska egenskaperna hos Al-Si-baserade legeringar. En ökning av Si innehålleti Al-legeringar förbättrar de mekaniska egenskaperna såsom brott och sträckgräns samt hårdhet hos materialen, men minskar duktiliteten. En ökning med Si halt i Al-legeringar minskar dessvärre tjockleken hos oxidskiktet, och därigenom, försämrar oxidskiktets korrosionsskydd.
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"Optimisation of the mechanical properties of a modified aluminium 7% silicon-magnesium casting alloy by heat treatment." Thesis, 2015. http://hdl.handle.net/10210/14584.
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Due to the problem of obtaining the predicted mechanical properties for Al-Si alloys, especially after heat treatment, trial batches of sodium, strontium and unmodified alloys were cast. The alloys were cast using a standard test bar design. The material was solution treated, quenched and aged (at both increasing time and temperature) to obtain the best properties possible. Initial background information and theory was obtained at libraries to obtain a better working knowledge of the alloy...