Dissertations / Theses: 'Aluminum alloys. Aluminum Materials'

1

Lebeau, Thomas. "Wetting of alumina-based ceramics by aluminum alloys." Thesis, McGill University, 1993. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=68039.

Full text

Abstract:

During the last 20 years, ceramic fiber reinforced metal matrix composites, referred to as MMCs, have provided a relatively new way of strengthening metals. High specific modulus and a good fatigue resistance in dynamic loading conditions or for high temperature applications make these composites very attractive for replacing classic alloys. The first requirement for the fabrication of MMCs, especially by processes involving liquid metals, is a certain degree of wetting of fibers by the liquid metal which will permit a good bonding between the two phases.
The conventional experimental approach to wettability consists of measuring the contact angle of a drop of the liquid metal resting on flat substrate of the ceramic reinforcement materials.
This work deals with the fabrication of eutectic $ rm ZrO sb2/Al sb2O sb3 (ZA), ZrO sb2/Al sb2O sb3/TiO sb2$ (ZAT), and $ rm ZrO sb2/Al sb2O sb3/SiO sb2$ (ZAS) ceramic substrates and the study of their wetting behavior by different classes of Al alloys. Wetting experiments were performed under high vacuum or under ultra high purity Ar atmosphere. Four major variables were tested to study the wetting behavior of the different ceramic/metal systems. Variables include holding time, melt temperature, alloy and ceramic compositions.
Ceramic materials were sintered under vacuum at temperatures ranging from 1500$ sp circ$C to 1790$ sp circ$C for 2.5 hours, and achieved over 96% of the theoretical density. An experimental set-up was designed to measure in-situ contact angles using the sessile drop method. For any ceramic substrate, a temperature over 950$ sp circ$C was necessary to observe an equilibrium wetting angle less than 90$ sp circ$ with pure Al; by alloying the aluminum, wetting could be observed at lower temperatures ($ theta$ = 76-86$ sp circ$ at 900$ sp circ$C for Al-10wt%Si, $ theta sim72 sp circ$ at 850$ sp circ$C for Al-2.4wt%Mg). Finally, ZAS specimens reacted with molten Al alloys over 900$ sp circ$C to produce Zr-Al based intermetallics at the metal/ceramic interface.

APA, Harvard, Vancouver, ISO, and other styles

2

Fransson, Christoffer. "Accelerated aging of aluminum alloys." Thesis, Karlstad University, Karlstad University, Karlstad University, Karlstad University, 2009. http://urn.kb.se/resolve?urn=urn:nbn:se:kau:diva-5041.

Full text

Abstract:

In order to determine storage life for aluminum alloys it is essential to have a good knowledge on the accelerated aging behavior and the mechanical properties that are affected. The selected aluminum alloys are AA2017, AA6082, AA7075 and the study has been focused on their impact toughness and hardness relation to aging beyond peak conditions. To be able to plot the mechanical properties versus aging time and temperature, Differential Scanning Calorimetric runs have been the key to obtain supporting activation energies for a specific transformation. The activation energies have been calculated according to the Kissinger method, plotted in Matlab. Arrhenius correlation has also been applied to predict the natural aging time for long time storage in 30 degrees Celsius. It could be concluded that the results from the mechanical test series show that the constructed Arrhenius 3D method did not meet the expectations to extrapolate constant activation energies down to storage life condition. Scanning electron microscopy together with light optical microscopy analyses show how important it is to apply notches in proper test specimen directions and how precipitates are grown, as it will affect impact toughness and hardness.

An ending discussion is held to explain how mechanical testing progressed and how other external issues affected the master thesis operations.

APA, Harvard, Vancouver, ISO, and other styles

3

Gammage, Justin Wilkinson D. S. "Damage in heterogeneous aluminum alloys /." *McMaster only, 2002.

Find full text

APA, Harvard, Vancouver, ISO, and other styles

4

Gustafsson, Sofia. "Corrosion properties of aluminium alloys and surface treated alloys in tap water." Thesis, Uppsala universitet, Institutionen för materialkemi, 2011. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-157527.

Full text

Abstract:

The aim of this thesis is to obtain a basic knowledge of the factors that affect corrosion of aluminium in tap water for different kinds of applications like water pipes for tap water, solar systems, HVAC&R-applications (like fan coil units on chillers) and heat sinks for electronic or industrial applications. Open systems are used in some applications and closed systems in others. There is a clear difference in the corrosion behaviour of these two systems. The main reasons for this difference are that the content of oxygen differs between the two systems and also that inhibitors can be used in closed systems to hinder corrosion. In this thesis focus will be on corrosion in open systems. The corrosion properties in tap water for different alloys of aluminium and different surface treatments have been examined. The influences on corrosion of the oxygen content in water and the iron content in aluminium alloys have been investigated. The corrosion properties of an aluminium alloy in deionised water have also been examined.

APA, Harvard, Vancouver, ISO, and other styles

5

Huang, Ting-Yun Sasha. "Stability of nanostructured : amorphous aluminum-manganese alloys." Thesis, Massachusetts Institute of Technology, 2016. http://hdl.handle.net/1721.1/104107.

Full text

Abstract:

Thesis: Ph. D., Massachusetts Institute of Technology, Department of Materials Science and Engineering, 2016.
This electronic version was submitted by the student author. The certified thesis is available in the Institute Archives and Special Collections.
Cataloged from student-submitted PDF version of thesis.
Includes bibliographical references (pages 113-122).
Nanocrystalline alloys have attracted interest for decades because of their improved mechanical strength without sacrificing ductility, but structural stability has always been an issue. In this work, bulk aluminum-manganese (Al-Mn) nanocrystalline alloys have been synthesized using room temperature ionic liquid electrodeposition, by which various nanostructures and dual-phase structures can be created by controlling the Mn solute incorporation level. The manganese exhibits grain boundary segregation in the Al-Mn solid solution in the as-deposited condition, which contributes to enhanced stability of the nanostructure. The grain boundary properties of the nanostructured alloys were studied via three dimensional atom probe tomography and aberration-corrected scanning electron microscopy. The segregation energies were calculated based on the experimental results and compared with the values calculated from a thermodynamic-based segregation model. Upon heating of the nanostructured and dual-phase alloys, a variety of complex phase transformations occur. A combination of X-ray diffraction, transmission electron microscopy, as well as differential scanning calorimetry were employed to understand the phase transformation mechanisms and grain growth processes. A Johnson-Mehl-Avrami-Kolmogorov analytical model was proposed as a descriptive method to explain the phase transformation sequence. Using the parameters extracted from the analytical model, predictive time-temperature transformation diagrams were constructed. The stability region of the alloy in time-temperature space is thus established, providing a simple way to evaluate nanostructure stability.
by Ting-Yun Sasha Huang.
Ph. D.

APA, Harvard, Vancouver, ISO, and other styles

6

Liu, Li. "Évaluation de la propreté des alliages d'aluminium de fonderie A356.2 et C357 à l'aide de la technique PoDFA /." Thèse, Chicoutimi : Université du Québec à Chicoutimi, 1997. http://theses.uqac.ca.

Full text

APA, Harvard, Vancouver, ISO, and other styles

7

Ozbakir, Erol. "Development of aluminum alloys for diesel-engine applications." Thesis, McGill University, 2009. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=32568.

Full text

Abstract:

Weight reduction in vehicles has important benefits of fuel economy and reduction in greenhouse gas emissions as well as improved vehicle performance. The current material for the diesel-engine block/head is mostly ductile iron and replacing it with aluminum alloys would result in very effective weight reduction (30-40%). Current commercial cast aluminum alloys, however, soften at engine operating temperatures exceeding 200°C and would cause early fracture in the diesel engine. Two new alloys derived from the commercial alloy (A356) are described in terms of microstructure, creep, aging behavior and tensile properties at elevated temperatures. The alloy containing both peritectic (Cr, Zr and Mn) and age hardenable elements (Cu and Mg) shows superior aging response at 200°C (for 200 hours) and creep properties at 300°C (for 300 hours). Interestingly, the alloy has better tensile strength (161MPa) at 250°C with adequate ductility compared to the current engine alloys, A356 and A356+Cu. The improvement in mechanical properties is attributed to the newly formed thermally stable fine precipitates (ε-AlZrSi, α-AlCrMnFeSi…) inside the α-Al dendrites.
La diminution du poids des véhicules résulte dans l'apport important de bénéfices au niveau de l'économie d'essence, la réduction des gaz à effets de serre aussi bien que l'amélioration du rendement du véhicule. Le matériau principal présentement utilisé pour la fabrication de la tête et du bloc moteur est la fonte ductile. Le remplacement de la fonte par des alliages d'aluminium va conduire vèrs une diminution (30-40%) significative du poids. Les alliages d'aluminium de coulée actuels laissent voir dans le temps un ramolissement du métal lorsque les températures d'opération du moteur exèdent 200ºC. Ce phénomène provoquera à plus ou moins brève échéance un bris prématuré du moteur diésel. Deux nouveaux alliages développés à partir de l'alliage commercial A356 sont présentés dans les termes suivants : microstructure, fluage, comportement au vieillissement et propriétés de traction à des températures élevées. L'alliage contenant les deux groupes d'éléments soit péritectiques (Cr, Zr et Mn) dans un premier temps et pour le durcissement structural par le vieillissement (Cu et Mg) dans un second temps, démontre une réponse supérieure au vieillissement à la température de 200ºC pour une période de 200 heures et de meilleures propriétés de fluage à la température de 300ºC pour une période de 300 heures. De façon plus intéressant, l'alliage possède de meilleures propriétés de traction (161MPa) à 250ºC avec une ductilité adéquate comparativement aux alliages de bloc moteur fabriqués à partir des alliages A356 et A356 + Cu. L'amélioration des propriétés mécaniques est ainsi attribuable aux nouveaux précipit

APA, Harvard, Vancouver, ISO, and other styles

8

Fauré, Philippe L. "Aluminium : production processes and architectural application." Thesis, McGill University, 1987. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=63919.

Full text

APA, Harvard, Vancouver, ISO, and other styles

9

Diewwanit, Ittipon. "Semi-solid processing of hypereutectic aluminum-silicon alloys." Thesis, Massachusetts Institute of Technology, 1996. http://hdl.handle.net/1721.1/10860.

Full text

APA, Harvard, Vancouver, ISO, and other styles

10

Oh, Se-Yong. "Wetting of ceramic particulates with liquid aluminum alloys." Thesis, Massachusetts Institute of Technology, 1987. http://hdl.handle.net/1721.1/14643.

Full text

APA, Harvard, Vancouver, ISO, and other styles

11

Kharal, Shankar Prasad. "Modelling Sensitization Dynamics in 5xxx Series Aluminum Alloys." Thesis, University of Louisiana at Lafayette, 2018. http://pqdtopen.proquest.com/#viewpdf?dispub=10682751.

Full text

Abstract:

This thesis addresses the use of the Johnson-Mehl-Avrami-Kolmogorov (JMAK) model for better understanding of kinetics of crystallization of the beta-phase in sensitized aluminum alloys. Three acoustic parameters: longitudinal velocity, transverse velocity, and attenuation coefficient for longitudinal waves, are modeled as a function of time as the beta-phase volume fraction increases. The acoustic parameters were previously measured in the same laboratory with two ultrasonic techniques, Resonant Ultrasound Spectroscopy (RUS) and Pulse Echo (PE), on sensitized samples of Al5083-H116 and Al5456-H116. In this investigation, a comparative study of beta-phase kinetics in terms of the phase transformation rate constant, k, and Avrami exponent, n, was performed on the three acoustic parameters, to understand their evolution with the degree of sensitization. The values of n indicate a combination of 2D to 1D growth at the grain boundaries and at their intersections. The values of k grow non-linearly with the heat-treatment temperature; k is higher for the attenuation coefficient as compared with that for velocity.

APA, Harvard, Vancouver, ISO, and other styles

12

Lauer, Mark Anthony. "Modeling Macrosegregation in Directionally Solidified Aluminum Alloys." Diss., The University of Arizona, 2015. http://hdl.handle.net/10150/556855.

Full text

Abstract:

This dissertation explores macrosegregation in directionally solidified aluminum castings. Two methods of interpolating thermocouple data are presented. A method using Lagrangian polynomials to interpolate thermocouple profiles is described and gives the best results for steady state furnace conditions. Using cubic splines to interpolate temperatures works best under transient conditions. A simple model, neglecting convection, is presented for predicting macrosegregation during melting, holding, and solidification of a sample and is compared with existing models. The model is able to accurately capture macrosegregation in microgravity experiments and is verified by experimental results. A two dimensional model of solidification, including convection, is presented and used to simulate samples grown in microgravity and terrestrially. The terrestrial samples exhibit steepling convection, while the microgravity samples do not. Causes of the steepling convection are explored and quantitative comparisons are made against experimental samples, with good agreement. The role of the furnace temperature profile is discussed and it is shown how it can be used to manipulate the steepling convection. Simulations of directional solidification through changes in cross section are presented for four experiments in graphite molds and one hypothetical experiment in an alumina mold. When solidifying through a contraction in cross section, the mold material is shown to have a strong influence on the convection and resulting macrosegregation. When solidifying out of an expansion, there is less of a difference between the two mold materials. Qualitative comparisons are made against experimentally obtained microstructures and good agreement is found. Stray grains were found, at the expansion, in some of the experimental samples and an explanation based on the results of the simulations is given.

APA, Harvard, Vancouver, ISO, and other styles

13

Klinter, Andreas. "Wetting behaviour of aluminum alloys on ceramic substrates and its effect on the stability of aluminum foams." Thesis, McGill University, 2010. http://digitool.Library.McGill.CA:8881/R/?func=dbin-jump-full&object_id=92344.

Full text

APA, Harvard, Vancouver, ISO, and other styles

14

Cheng, Xiang-Ming. "TEXTURE, MICROSTRUCTURE AND FORMABILITY OF ALUMINUM ALLOYS." UKnowledge, 2001. http://uknowledge.uky.edu/gradschool_diss/392.

Full text

Abstract:

Texture, microstructure and formability were studied in Direct Chill Cast (DC) and Strip Cast (SC) aluminum alloys with regard to crystallographic anisotropy, the Portevin-Le Chatelier effect and aging softening behavior. It was found that material properties change greatly with manufacturing processes (DC vs. SC) and chemical composition (3xxx vs. 5 xxx alloys). DC cast hot band materials are usually fully recrystallized and have strong softening textures while SC hot band materials have a rolling structure with strong deformation textures. Softening textures cause 90 earing while deformation textures result in 45 earing after deep drawing. During cold rolling, 90 earing in DC cast hot band materials decreases and eventually changes to 45 earing after certain degrees of cold reduction. Correspondingly, the intensity of the softening texture components in DC cast hot band materials decreases while the intensity of deformation texture components increases with increasing degrees of cold reduction. These two kinds of textures interact and attempt to balance each other during cold rolling which produces resultant earing. However, this is not true for SC hot band materials since it's hard to obtain strong softening textures and thus 90 earing in these materials. 5 xxx Al-Mg alloys are more difficult to work than 3 xxx aluminum alloys. Elevated temperature annealing which greatly reduces the strength (hardness) improves significantly the workability of Al-Mg alloys. On the other hand, the Portevin-Le Chatelier effect and aging softening behavior are stronger in Al-Mg alloys than in 3xxx aluminum alloys and both increase with increasing cold reduction and with increasing Mg content. An apparent tensile anisotropy exists in as received SC hot band materials. The tensile yield strength (YS) is smaller in the QD (45 to the rolling direction), and larger in the RD (rolling direction) and the TD (transverse direction). There is no obvious difference in YS between these RD and TD directions. The average stress drop of serrations in the PLC effect, D s , is strongest in the TD, smallest in the RD with QD in between but closer to TD. However, no tensile anisotropy was observed in a fully recrystallized DC hot band or in solution treated SC hot band materials. It was found that a rolling structure favors mechanical anisotropy while a recrystallized structure prevents it. The tensile anisotropy is due to anisotropic distributions of microstructures, i.e., dislocations, precipitates and solute atoms. A random microstructure is associated with material that shows little or no mechanical anisotropy. An elongated or preferably orientated microstructure is associated with material with high mechanical anisotropy. Recovery thermal treatments at sufficiently high temperatures so that dislocation annihilation and microstructure rearrangement occurs when applied to the final gauge material also lowers mechanical anisotropy because of the reduction in intensity of the elongated (preferably orientated) microstructure. In addition, plastically deforming the material in a more homogenous manner (such as cross rolling as compared to straight rolling) produces a more uniform microstructure with an accompanying lower mechanical anisotropy.

APA, Harvard, Vancouver, ISO, and other styles

15

Dixon, Robert Gordon. "Microstructure/property relationships for carbon fiber reinforced aluminum alloys." Thesis, Massachusetts Institute of Technology, 1985. http://hdl.handle.net/1721.1/15127.

Full text

Abstract:

Thesis (M.S.)--Massachusetts Institute of Technology, Dept. of Materials Science and Engineering, 1985.
MICROFICHE COPY AVAILABLE IN ARCHIVES AND SCIENCE.
Bibliography: leaves 104-107.
by Robert Gordon Dixon, Jr.
M.S.

APA, Harvard, Vancouver, ISO, and other styles

16

Gavelius, Marianne, and Karin Andersson. "Surface Treatment for Additive Manufactured Aluminum Alloys." Thesis, Linköpings universitet, Molekylär ytfysik och nanovetenskap, 2020. http://urn.kb.se/resolve?urn=urn:nbn:se:liu:diva-169027.

Full text

Abstract:

Manufacturing of aircraft parts is often complex and time-consuming, which has led to an increased interest in new manufacturing technologies in the Swedish industry such as additive manufacturing (AM). Additive manufacturing techniques could be a solution to meet the aircrafts’ demand since it contributes to an efficient manufacturing and allows a just-in-time production of complex metal parts in their final shape. However, the use of AM aluminum for aircraft applications is in a development phase and no surface treatment process exists. Thereby, it is of high interest to further investigate surface treatments for AM alloys. Currently at Saab AB, conventional aluminum alloys are generally anodized in tartaric sulphuric acid (TSA) to improve the corrosion resistance and adhesion properties of the metal. On the behalf of Saab AB, there is also an interest in establishing powder coating as a surface treatment. This master thesis’ purpose is to investigate the anodizing and adhesion properties for the two additive manufacturing alloys - AlSi10Mg and ScalmalloyⓇ, and compare it with the conventionally produced Al alloy 2024-T3. The anodization and the powder coating is examined by using following characterization techniques: profilometry, light microscopy, scanning electron microscopy and contact angle measurements. The results from the experimental part indicated successful anodizations for all the alloys and good adhesion properties for powder coating. This research is a first step in contributing to a better understanding of the anodic coating and adhesion properties for the AM samples ScalmalloyⓇ and AlSi10Mg

APA, Harvard, Vancouver, ISO, and other styles

17

Su, Jing. "Hot deformation behaviour of micro-alloyed magnesium- aluminum-calcium alloys during hot compression." Thesis, McGill University, 2013. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=114554.

Full text

Abstract:

Magnesium alloys have attracted a great deal of attention as structural materials for automotive applications, due to their low density, high specific strength and high specific stiffness. However, poor formability, due to a strong crystallographic texture in Mg alloy sheet, is a major issue. In this thesis, alloys have been designed to form precipitates during hot compression at the industrial hot rolled temperatures, since this might influence dynamic recrystallization and texture. Based on thermodynamic calculations, two micro-alloyed Mg alloys, Mg-0.3Al-0.2Ca (AX0302) and Mg-0.1Al-0.5Ca (AX0105), were designed such that the equilibrium precipitation (Al2Ca and Mg2Ca, respectively) temperatures are in the hot rolling range (300 °C to 400 °C).Both alloys were cast in a copper mould, and the ingots were solution treated at 500 °C for 8 h to dissolve the eutectic precipitates and homogenize the distribution of the alloying elements. In order to investigate precipitation characteristics, isothermal heat treatment (aging) were performed at 250 °C to 400 °C for a time range from 10 min to 32 h. To understand the effect of deformation parameters on hot deformation characteristics, including precipitation, hot compression tests were conducted on homogenized specimens at temperatures from 300 °C to 450 °C with three strain rates of 0.1s-1, 0.01s-1, 0.001s-1 to strains of 10%, 30%, 60% and 90%. As well as precipitation, the deformation substructures and dynamic recrystallization was characterized using the flow curves, SEM with BSE and EDS detectors and optical microscopy was used to characterize microstructure mainly on DRX and twins, X-ray diffraction was used to measure texture and micro-hardness was conducted to study the room temperature properties of aged and hot compressed samples.Strain induced dynamic precipitation occurred in both alloys during hot compression at under all conditions except at temperatures where precipitation was not predicted (by FactSage) to occur. The effect of temperature and strain rate on the size and volume fraction of DRX grains was studied.The results indicated that the size and amount of DRX grains increased as Z parameter decreased. However, compared with two alloys, the effect of Z on DRX is more sensitive to AX0302 than AX0105, which could be related to larger amount of precipitates in AX0105. Texture was not clearly affected by changes in precipitate amounts, but higher temperature slightly decreased the intensity of the basal texture, which may due to the activation of non-basal slip.
Le magnésium et ses alliages ont attiré beaucoup d'attention en tant que matériaux de structure pour les applications automobiles, en raison de leur faible densité, haute résistance spécifique et haute rigidité spécifique. Cependant, la faible formabilité, en raison d'une forte texture cristallographique dans la feuille de Mg, est un enjeu majeur. Dans cette mémoire, des alliages ont été conçus pour former des précipités lors de la compression à chaud à des températures chaudes utilisées en industries, car cela pourrait influencer la recristallisation dynamique et la texture.Sur la base de calculs thermodynamiques, deux micro-allié de Mg-Al-Ca alliages, Mg-0.3 Al-0.2Ca (AX0302) et Mg-0.1Al-0.5Ca (AX0105), ont été conçus de telle sorte que la précipitation d'équilibre (Al2Ca et Mg2Ca, respectivement) sont des températures dans l'intervalle de laminage à chaud (300°C à 400°C). Les deux alliages ont été coulés dans un moule en cuivre, et les lingots ont été mises en solution à 500°C pendant 8 h à dissoudre les précipités eutectiques et homogénéiser la répartition des éléments d'alliage Afin d'étudier les caractéristiques des précipitations, un traitement thermique isotherme (vieillissement) ont été réalisées à 250°C à 400°C pendant un intervalle de temps de 10 minutes à 32 heures. Pour comprendre l'effet de déformation sur des caractéristiques de déformation à chaud, y compris les précipitations, les essais de compression à chaud ont été réalisés sur des échantillons homogénéisés à une température de 300°C à 450°C avec trois taux de déformation de 0.1s-1, 0,01s-1, 0,001s-1 à 10% de souches, 30%, 60% et 90%. Ainsi que les précipitations, les structures de déformation et de recristallisation dynamique a été caractérisé en utilisant les courbes d'écoulement, MEB (microscope électronique à balayage) de l'ESB et des détecteurs EDS et microscopie optique a été utilisé pour caractériser la microstructure principalement sur DRX et les jumeaux, diffraction des rayons-X a été utilisée pour texture et de mesure de micro-dureté a été menée pour étudier les propriétés de température ambiante de personnes âgées et chaude échantillons comprimés. La quantité de précipités dans AX0105 est plus importante que celle de AX0302 lors de la compression et de vieillissement chaud, qui conviennent à la tendance identifiées par les prédictions thermodynamiques à l'aide du logiciel FactSage. Égoutter les précipitations induite dynamique s'est produite dans les deux alliages lors de la compression à chaud à toutes les conditions, sauf à des températures où les précipitations n'ont pas été prévues (par FactSage) de se produire. Après compression à chaud, une structure de grain partiellement recristallisé a été obtenue constitué de fines dynamiques grains recristallisés aux limites de grains grossiers d'origine et/ou sur les jumeaux dans les deux alliages à une souche de 90% à toutes les conditions de déformation dans cette étude. La contrainte d'écoulement des deux alliages peuvent être représentés par ZenerHollomen fonction des paramètres (Z). L'effet de la température et de la vitesse de déformation sur la fraction de taille et de volume de grains DRX a été étudiée. Les résultats ont indiqué que la taille et la quantité de grains DRX augmenté lorsque le paramètre Z diminué. Cependant, par rapport à deux alliages, l'effet de Z sur DRX est plus sensible à AX0302 que AX0105, ce qui pourrait être lié à une plus grande quantité de précipités dans AX0105. La texture n'est pas clairement influencée par des changements dans les quantités de précipité, mais des plus hautes températures diminue légèrement l'intensité de la texture de base, qui peut être dû à l'activation de glissement non-basal.

APA, Harvard, Vancouver, ISO, and other styles

18

Lee, Jonghee. "Fracture analysis of a propagating crack in a ductile material /." Thesis, Connect to this title online; UW restricted, 1996. http://hdl.handle.net/1773/7081.

Full text

APA, Harvard, Vancouver, ISO, and other styles

19

CHANDRASEKARAN, SENTHILKUMAR. "ELECTRODEPOSITION OF BIS-SILANE FOR THE PRETREATMENT OF ALUMINUM ALLOYS." University of Cincinnati / OhioLINK, 2006. http://rave.ohiolink.edu/etdc/view?acc_num=ucin1155647381.

Full text

APA, Harvard, Vancouver, ISO, and other styles

20

Huang, Tsai-Shang. "On the intergranular corrosion of 7xxx aluminum alloys." Columbus, Ohio : Ohio State University, 2005. http://rave.ohiolink.edu/etdc/view?acc%5Fnum=osu1133365169.

Full text

APA, Harvard, Vancouver, ISO, and other styles

21

Jones, Kimberly A. "The creep behavior of aluminum alloy 8009." Thesis, Georgia Institute of Technology, 1993. http://hdl.handle.net/1853/19630.

Full text

APA, Harvard, Vancouver, ISO, and other styles

22

Ruan, Shiyun. "Hard and tough electrodeposited aluminum-manganese alloys with tailored nanostructures." Thesis, Massachusetts Institute of Technology, 2010. http://hdl.handle.net/1721.1/59226.

Full text

Abstract:

Thesis (Ph. D.)--Massachusetts Institute of Technology, Dept. of Materials Science and Engineering, 2010.
Includes bibliographical references (p. 131-142).
Tailoring the nanostructure of electrodeposited Al-Mn films to achieve high hardness and toughness is the overarching goal of this thesis. Binary Al-Mn alloys are electrodeposited using a conventional current waveform in a chloroaluminate electrolyte at ambient temperature. It is found that alloys with low Mn contents comprise micrometer-sized FCC grains. At intermediate Mn contents, the FCC grain size decreases abruptly to the nanometer regime upon the appearance of a secondary amorphous phase. In these dual-phase alloys, the phases are distributed in a characteristic domain-network structure. At high Mn contents, an amorphous phase that contains pre-existing nanoquasicrystalline nuclei dominates. Leveraging the effects of surface kinetics at the electrode on the alloy microstructure, a reverse-pulse current waveform is designed to tailor the grain size and phase distribution of the electrodeposits; single phase FCC alloys with nanocrystalline grains, as well as dual-phase alloys with homogeneous phase distribution are synthesized. Solute distributions in these alloys are investigated using atom probe tomography. Implanted Ga ions are used as chemical markers for the amorphous phase; this method permits more robust phase identification and measurement of their compositions. Whereas uniform Mn distributions are observed in the single phase alloys, Mn is found to weakly partition into amorphous phase of the dual-phase alloy by ~2 at.%. Micro-indentation of the reverse-pulsed alloys and the guided bend tests reveal high hardness and toughness that are comparable to steels. High hardness is attributed to a combination of solid-solution strengthening effects and structural refinement; high toughness of the nanostructured alloys arises from the activation of both grain boundary- and dislocation-mediated deformation mechanisms; malleability of the amorphous alloys stems from the simultaneous operation of multiple shear bands during deformation. An unprecedented combination of high hardness, toughness and lightweight is thus achieved in our electrodeposited Al-Mn alloys.
by Shiyun Ruan.
Ph.D.

APA, Harvard, Vancouver, ISO, and other styles

23

Tan, Evren. "Severe Plastic Deformation Of Age Hardenable Aluminum Alloys." Phd thesis, METU, 2012. http://etd.lib.metu.edu.tr/upload/12614968/index.pdf.

Full text

Abstract:

Industrial products of high-strength Al-alloys are currently manufactured by thermo-mechanical processes, which are only applicable in the integrated plants requiring high investment cost. Moreover, reduction of the average grain size not less than 10 &mu
m and re-adjustment of process parameters for each alloy type is evaluated as disadvantage. Therefore, recently there have been many research studies for development of alternative manufacturing techniques for aluminum alloys. Research activities have shown that it is possible to improve the strength of Al-alloys remarkably by severe plastic deformation which results in ultra-fine grain size. This study aims to design and manufacture the laboratory scale set-ups for severe plastic deformation of aluminum alloys, and to characterize the severely deformed samples. The stages of the study are summarized below: First, for optimization of die design and investigation of parameters affecting the deformation finite element modeling simulations were performed. The effects of process parameters (die geometry, friction coefficient) and material properties (strain hardening, strain-rate sensitivity) were investigated. Next, Equal Channel Angular Pressing (ECAP) system that can severely deform the rod shaped samples were designed and manufactured. The variations in the microstructure and mechanical properties of 2024 Al-alloy rods deformed by ECAP were investigated. Finally, based on the experience gained, a Dissimilar Channel Angular Pressing (DCAP) system for severe plastic deformation of flat products was designed and manufactured
then, 6061 Al-alloy strips were deformed. By performing hardness and tension tests on the strips that were deformed by various passes, the capability of the DCAP set-up for production of ultra-fine grain sized high-strength aluminum flat samples were investigated.

APA, Harvard, Vancouver, ISO, and other styles

24

Silva, Beethoven Max Alves da. "Influencia da microestrutura inicial e material de molde na tixoconformação da liga A356." [s.n.], 2004. http://repositorio.unicamp.br/jspui/handle/REPOSIP/263687.

Full text

Abstract:

Orientador: Maria Helena Robert
Dissertação (mestrado) - Universidade Estadual de Campinas, Faculdade de Engenharia Mecanica
Made available in DSpace on 2018-08-06T16:34:52Z (GMT). No. of bitstreams: 1 Silva_BeethovenMaxAlvesda_M.pdf: 3678052 bytes, checksum: 2c49240a815892ad66565deba3473b59 (MD5) Previous issue date: 2007
Resumo: Neste trabalho investiga-se a influência da microestrutura inicial e do material do molde na tixoconformação da liga A356. São produzidas e testadas em operações de tixoforjamento pastas obtidas por três distintos processos: fusão parcial controlada de estrutlJ'aS dendríticas grosseiras, fusão parcial controlada de estruturas ultra-refinadas e pastas obtidas por agitação mecânica do líquido durante solidificação. É produzido ainda um compósito A356 + Ab03 obtido por compofundição. Os tixoforjados foram submetidos à análise metalográfica para caracterização microestrutural, medindo-se a fração da fase primária e o tamanho médio de glóbulo ou roseta da fase sólida. Os resultados obtidos mostram a viabilidade da utilização de moldes não metálicos e operações de tixoconformação com produtos de bom acabamento superficial e dimensional. As forças de tixoforjamento são dependentes da condição inicial da matéria-prima, de forma que forças maiores são requeridas com o aumento do parâmetro microestrutural básico (espaçamento interdendrítico, tamanho de glóbulo e tamanho de roseta) da matéria-prima
Abstract: This research aims the influence of initial microstructure and die material on thixofonning of A356 alloy. Obtained slurries are produced and tested in thixoforging operation by three distinct processes: controlled partial melting of coarse dendritic structures, controlled partial melting of ultra-refined structures and obtained slurries by liquid mechanical stirring during solidification. It is still produced a composite A356 + AbO:i obtained by compocasting. Thixoforged samples were submitted to metalographic analysis for microstructural characterisation, measuring the primary phase fraction and globule average size or 50lid phase rosette. Obtained results showed the viability of non-metallic dies in thixoforming operations with good superficial and dimensional finishing produds. Thixoforging forces are dependent on initial condition of raw material, 50 that higher forces are required with the increasing of basic microstructural parameter Onterdentritic spacing, globule size and rosette size) of raw material
Mestrado
Materiais e Processos de Fabricação
Mestre em Engenharia Mecânica

APA, Harvard, Vancouver, ISO, and other styles

25

Unocic, Kinga Angelika. "Structure-Composition-Property Relationships In 5xxx Series Aluminum Alloys." The Ohio State University, 2008. http://rave.ohiolink.edu/etdc/view?acc_num=osu1218473077.

Full text

APA, Harvard, Vancouver, ISO, and other styles

26

Hamilton, Benjamin Carter. "Creep behavior of aluminum alloys C415-T8 and 2519-T87." Diss., Georgia Institute of Technology, 1997. http://hdl.handle.net/1853/20497.

Full text

APA, Harvard, Vancouver, ISO, and other styles

27

Meyer-Rödenbeck, G. D. "An abrasive-corrosive wear evaluation of some aluminium alloys." Master's thesis, University of Cape Town, 1989. http://hdl.handle.net/11427/18784.

Full text

Abstract:

This investigation evaluates the abrasive-corrosive wear behaviour of aluminium alloys with the aim of establishing a data base of performance and guide lines for material optimisation. Wear test apparatus and standard tests developed by previous research programmes were utilised (Noel and Allen, 1981; Barker, 1988). Further tests were then devised for a more detailed characterisation of wear behaviour. Tests conducted showed that aluminium alloys have approximately a quarter to half the abrasion resistance of mild steel. Poor microfracture properties of Al-Si cast alloys were observed as a result of coarse and brittle silicon rich phases contained in the aluminium matrix. Non heat-treatable wrought alloys exhibit ductile micro-deformation characteristics whilst heat-treatable alloys, having the best abrasion resistance, possess better combinations of strength, hardness and toughness. Tests with combined corrosion and wear showed that most aluminium alloys are subject to pitting corrosion due to localised differences in electrode potentials at constituent sites. Higher series alloys with a large number of constituent particles exhibit higher pitting densities. Due to the high electrode potentials of silicon phases and copper and zinc solid solutions, the alloys LM6+Sr, 2014 and 7075 have poor corrosion resistance and are subject to localised and pitting attack. As a consequence the alloys 2014, 7075 and LM6+Sr show a decrease in wear performance under abrasive-corrosive conditions. In contrast the good corrosion resistance of the alloys 5083, 6261 and 7017 provide a significant improvement in wear performance under conditions of long corrosion periods with light abrasive intervals. This study concludes that the abrasion resistance of wrought alloys may be optimised by designing an alloy with a good combination of tensile strength, fracture toughness and hardness together with an intermediate microstructural size distribution of second phase particles in the aluminium matrix. Ageing of heat treatable alloys improves abrasion resistance significantly, peak hardness and strength conditions resulting in optimum abrasion properties.

APA, Harvard, Vancouver, ISO, and other styles

28

Zhao, Xinyan. "Exfoliation corrosion kinetics of high strength aluminum alloys." Columbus, Ohio : Ohio State University, 2006. http://rave.ohiolink.edu/etdc/view?acc%5Fnum=osu1140154773.

Full text

APA, Harvard, Vancouver, ISO, and other styles

29

Cinkilic, Emre. "Alloy Design and Precipitation Modeling of High Fe Concentration Recycled Cast Aluminum Alloys for Structural Applications." The Ohio State University, 2019. http://rave.ohiolink.edu/etdc/view?acc_num=osu1555599698005398.

Full text

APA, Harvard, Vancouver, ISO, and other styles

30

Borchers, Tyler Edward. "Weldability and Corrosion of 7xxx Series Aluminum Alloys." The Ohio State University, 2016. http://rave.ohiolink.edu/etdc/view?acc_num=osu1471362806.

Full text

APA, Harvard, Vancouver, ISO, and other styles

31

Whelchel, Ricky L. "Effects of microstructure on the spall behavior of aluminum-magnesium alloys." Diss., Georgia Institute of Technology, 2014. http://hdl.handle.net/1853/51845.

Full text

Abstract:

This research focuses on the spall properties of aluminum-magnesium (Al-Mg)alloys.Aluminum alloy 5083 (Al 5083) was used as a model alloy for the work performed in this study. Al-Mg alloys represent a light-weight and corrosion resistant alloy system often used in armor plating. It is desirable to process armor plate material to yield a microstructure that provides maximum resistance to spall failure due to blast and projectile impacts. The blast and impact resistance has often been quantified based on the measurement of the spall strength and the Hugoniot elastic limit (HEL). The spall properties of Al-Mg alloys were measured for four different microstructural states resultant from varying processing conditions. The four microstructures include: (a) textured grain structure from a rolled Al 5083-H116 plate, (b) sub-micron grain structure produced using equi-channel angular pressing (ECAP),(c) equiaxed grain structure, and (d) precipitation hardened microstucture from an Al-9wt.% Mg alloy. The overall results show that grain size is not the most dominant microstructural feature affecting spall strength in aluminum alloys, when the impact conditions are the same. Texture, especially if brittle inclusions align along the grains, appears to have the most dominant effect resulting in decreased spall strength. Furthermore, one-dimensional modeling shows that the inclusion size and distribution is the controlling factor for void formation during spalling. Grain size does affect the decompression rate dependence of each microstructure, whereby smaller grain sizes result in a larger power law exponent for fits of spall strength versus decompression rate. Unlike the spall strength, the HEL shows an increasing trend with decreased grain size, as would be expected from a Hall-Petch type effect, indicating that a smaller grain size is best for penetration resistance. Samples processed using ECAP alone provide the best combination of spall strength and HEL and therefore the most promise for improved blast and penetration resistance of aluminum-magnesium alloy armor plates.

APA, Harvard, Vancouver, ISO, and other styles

32

ASHIRGADE, AKSHAY A. "ENVIRONMENTALLY-COMPLIANT NOVOLAC SUPERPRIMERS FOR CORROSION PROTECTION OF ALUMINUM ALLOYS." University of Cincinnati / OhioLINK, 2006. http://rave.ohiolink.edu/etdc/view?acc_num=ucin1153245386.

Full text

APA, Harvard, Vancouver, ISO, and other styles

33

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.

Full text

APA, Harvard, Vancouver, ISO, and other styles

34

Dean, Nancy Frier. "Plane front stability and cellular solidification in fiber reinforced aluminum-copper alloys." Thesis, Massachusetts Institute of Technology, 1992. http://hdl.handle.net/1721.1/13242.

Full text

APA, Harvard, Vancouver, ISO, and other styles

35

Au, Hiu. "Pitting and crack initiation in high strength aluminum alloys for aircraft applications." Thesis, Massachusetts Institute of Technology, 1996. http://hdl.handle.net/1721.1/11240.

Full text

APA, Harvard, Vancouver, ISO, and other styles

36

Sumartha, Yusuf 1972. "Fluidity of rheocast A356 aluminum alloy." Thesis, Massachusetts Institute of Technology, 1997. http://hdl.handle.net/1721.1/10231.

Full text

APA, Harvard, Vancouver, ISO, and other styles

37

Addepalli, Swarnagowri. "High-Temperature Corrosion of Aluminum Alloys: Oxide-Alloy Interactions and Sulfur Interface Chemistry." Thesis, University of North Texas, 2000. https://digital.library.unt.edu/ark:/67531/metadc2739/.

Full text

Abstract:

The spallation of aluminum, chromium, and iron oxide scales is a chronic problem that critically impacts technological applications like aerospace, power plant operation, catalysis, petrochemical industry, and the fabrication of composite materials. The presence of interfacial impurities, mainly sulfur, has been reported to accelerate spallation, thereby promoting the high-temperature corrosion of metals and alloys. The precise mechanism for sulfur-induced destruction of oxides, however, is ambiguous. The objective of the present research is to elucidate the microscopic mechanism for the high-temperature corrosion of aluminum alloys in the presence of sulfur. Auger electron spectroscopy (AES), low energy electron diffraction (LEED), and scanning tunneling microscopy (STM) studies were conducted under ultrahigh vacuum (UHV) conditions on oxidized sulfur-free and sulfur-modified Al/Fe and Ni3Al(111). Evaporative deposition of aluminum onto a sulfur-covered iron surface results in the insertion of aluminum between the sulfur adlayer and the substrate, producing an Fe-Al-S interface. Aluminum oxidation at 300 K is retarded in the presence of sulfur. Oxide destabilization, and the formation of metallic aluminum are observed at temperatures > 600 K when sulfur is located at the Al2O3-Fe interface, while the sulfur-free interface is stable up to 900 K. In contrast, the thermal stability (up to at least 1100 K) of the Al2O3 formed on an Ni3Al(111) surface is unaffected by sulfur. Sulfur remains at the oxide-Ni3Al(111) interface after oxidation at 300 K. During annealing, aluminum segregation to the g ¢ -Al2O3-Ni3Al(111) interface occurs, coincident with the removal of sulfur from the interfacial region. A comparison of the results observed for the Al2O3/Fe and Al2O3/Ni3Al systems indicates that the high-temperature stability of Al2O3 films on aluminum alloys is connected with the concentration of aluminum in the alloy.

APA, Harvard, Vancouver, ISO, and other styles

38

Sidhar, Harpreet. "Friction Stir Welding of High Strength Precipitation Strengthened Aluminum Alloys." Thesis, University of North Texas, 2016. https://digital.library.unt.edu/ark:/67531/metadc862787/.

Full text

Abstract:

Rising demand for improved fuel economy and structural efficiency are the key factors for use of aluminum alloys for light weighting in aerospace industries. Precipitation strengthened 2XXX and 7XXX aluminum alloys are the key aluminum alloys used extensively in aerospace industry. Welding and joining is the critical step in manufacturing of integrated structures. Joining of precipitation strengthened aluminum alloys using conventional fusion welding techniques is difficult and rather undesirable in as it produces dendritic microstructure and porosities which can undermine the structural integrity of weldments. Friction stir welding, invented in 1991, is a solid state joining technique inherently benefitted to reduces the possibility of common defects associated with fusion based welding techniques. Weldability of various 2XXX and 7XXX aluminum alloys via friction stir welding was investigated. Microstructural and mechanical property evolution during welding and after post weld heat treatment was studied using experimental techniques such as transmission electron microscopy, differential scanning calorimetry, hardness testing, and tensile testing. Various factors such as peak welding temperature, cooling rate, external cooling methods (thermal management) which affects the strength of the weldment were studied. Post weld heat treatment of AL-Mg-Li alloy produced joint as strong as the parent material. Modified post weld heat treatment in case of welding of Al-Zn-Mg alloy also resulted in near 100% joint efficiency whereas the maximum weld strength achieved in case of welds of Al-Cu-Li alloys was around 80-85% of parent material strength. Low dislocation density and high nucleation barrier for the precipitates was observed to be responsible for relatively low strength recovery in Al-Cu-Li alloys as compared to Al-Mg-Li and Al-Zn-Mg alloys.

APA, Harvard, Vancouver, ISO, and other styles

39

Chintalapati, Pavan. "Solidification under pressure of aluminum castings." Birmingham, Ala. : University of Alabama at Birmingham, 2009. https://www.mhsl.uab.edu/dt/2010r/chintalapati.pdf.

Full text

Abstract:

Thesis (Ph. D)--University of Alabama at Birmingham, 2009.
Title from PDF t.p. (viewed June 30, 2010). Additional advisors: Viola L. Acoff, Krishan K. Chawla, Raymond J. Donahue, Gregg M. Janowski, Harry E. Littleton (ad hoc). Includes bibliographical references (p. 143-138).

APA, Harvard, Vancouver, ISO, and other styles

40

Keles, Ozgur. "Production And Characterization Of Alumina Fiber Reinforced Squeeze Cast Aluminum Alloy Matrix Composites." Master's thesis, METU, 2008. http://etd.lib.metu.edu.tr/upload/12609726/index.pdf.

Full text

Abstract:

The aim of the present study was to investigate the effects of different levels of Saffil alumina fiber addition, magnesium content in aluminum alloy matrix and casting temperature on the mechanical behavior, microstructure and physical properties of short fiber reinforced aluminum matrix composites. The main alloying element silicon was kept constant at 10 wt%. Magnesium contents were selected as 0.3 wt% and 1 wt%. Saffil alumina fiber preforms varied from 10 to 30 vol%. The casting temperatures were fixed at 750 °
C and 800 °
C. Micro porosity was present at the fiber-fiber interactions. Closed porosity of the composites increased when fiber vol% increased, however, variation in casting temperature and magnesium content in matrix did not have influence on porosity. Hardness of the composites was enhanced with increasing fiber vol%, magnesium content in matrix and decreasing casting temperature. Alignment of fibers within the composite had an influence on hardness
when fibers were aligned perpendicular to the surface, composites exhibited higher hardness. The highest hardness values obtained from surfaces parallel and vertical to fiber orientation were 155.6 Brinell hardness and 180.2 Brinell hardness for AlSi10Mg1 matrix 30 vol% alumina fiber reinforced composite cast at 800 °
C and at 750 °
C, respectively. 30 vol% Saffil alumina fiber reinforced AlSi10Mg0.3 matrix composite cast at 750 °
C showed the highest flexural strength which is 548 MPa. Critical fiber content was found as 20 vol% for all composites.

APA, Harvard, Vancouver, ISO, and other styles

41

Ridgeway, Colin D. "Integrated Computational Materials Engineering (ICME) of Aluminum Solidification and Casting." The Ohio State University, 2020. http://rave.ohiolink.edu/etdc/view?acc_num=osu1587378327014374.

Full text

APA, Harvard, Vancouver, ISO, and other styles

42

Dutt, Aniket Kumar. "Microstructural Evolution and Mechanical Response of Materials by Design and Modeling." Thesis, University of North Texas, 2017. https://digital.library.unt.edu/ark:/67531/metadc984205/.

Full text

Abstract:

Mechanical properties of structural materials are highly correlated to their microstructure. The relationship between microstructure and mechanical properties can be established experimentally. The growing need for structural materials in industry promotes the study of microstructural evolution of materials by design using computational approaches. This thesis presents the microstructural evolution of two different structural materials. The first uses a genetic algorithm approach to study the microstructural evolution of a high-temperature nickel-based oxide-dispersion-strengthened (ODS) alloy. The chosen Ni-20Cr ODS system has nano Y2O3 particles for dispersion strengthening and submicron Al2O3 for composite strengthening. Synergistic effects through the interaction of small dispersoids and large reinforcements improved high-temperature strength. Optimization considered different weight factors on low temperature strength, ductility, and high temperature strength. Simulation revealed optimal size and volume fraction of dispersoids and reinforced particles. Ni-20Cr-based alloys were developed via mechanical alloying for computational optimization and validation. The Ni-20Cr-1.2Y2O3-5Al2O3 alloy exhibited significant reduction in the minimum creep rate (on the order of 10-9 s-1) at 800oC and 100 MPa. The second considers the microstructural evolution of AA 7050 alloy during friction stir welding (FSW). Modeling the FSW process includes thermal, material flow, microstructural and strength modeling. Three-dimensional material flow and heat transfer model was developed for friction stir welding process of AA 7050 alloy to predict thermal histories and extent of deformation. Peak temperature decreases with the decrease in traverse speed at constant advance per revolution, while the increase in tool rotation rate enhances peak temperature. Shear strain is higher than the longitudinal and transverse strain for lower traverse speed and tool rotation rate; whereas for higher traverse speed and tool rotation rate, shear and normal strain acquire similar values. Precipitation distribution simulation using TC-PRISMA predicts the presence of η' and η in the as-received AA 7050-T7451 alloy and mostly η in the friction stir welded AA7050 alloy, which results in the lower predicted strength of friction stir welded alloy. Further, development of modeling assists in process optimization and innovation, and enhances the progression rate. Accelerating the development process requires coupling experimental methods with predictive modeling. The overall purpose of this work was to develop an integrated computational model with predictive capabilities. In the present work, an application tool to predict thermal histories during FSW of AA7050 was developed using COMSOL software.

APA, Harvard, Vancouver, ISO, and other styles

43

Martinez, Nelson Y. "Friction Stir Welding of Precipitation Strengthened Aluminum 7449 Alloys." Thesis, University of North Texas, 2016. https://digital.library.unt.edu/ark:/67531/metadc862775/.

Full text

Abstract:

The Al-Zn-Mg-Cu (7XXX series) alloys are amongst the strongest aluminum available. However, they are considered unweldable with conventional fusion techniques due to the negative effects that arise with conventional welding, including hydrogen porosity, hot cracking, and stress corrosion cracking. For this reason, friction stir welding has emerged as the preferred technique to weld 7XXX series alloys. Aluminum 7449 is one of the highest strength 7XXX series aluminum alloy. This is due to its higher zinc content, which leads to a higher volume fraction of eta' precipitates. It is typically used in a slight overaged condition since it exhibits better corrosion resistance. In this work, the welds of friction stir welded aluminum 7449 were studied extensively. Specific focus was placed in the heat affected zone (HAZ) and nugget. Thermocouples were used in the heat affected zone for three different depths to obtain thermal profiles as well as cooling/heating profiles. Vicker microhardness testing, transmission electron microscope (TEM), and differential scanning calorimeter (DSC) were used to characterize the welds. Two different tempers of the alloy were used, a low overaged temper and a high overaged temper. A thorough comparison of the two different tempers was done. It was found that highly overaged aluminum 7449 tempers show better properties for friction stir welding. A heat gradient along with a high conducting plate (Cu) used at the bottom of the run, resulted in welds with two separate microstructures in the nugget. Due to the microstructure at the bottom of the nugget, higher strength than the base metal is observed. Furthermore, the effects of natural aging and artificial aging were studied to understand re-precipitation. Large improvements in strength are observed after natural aging throughout the welds, including improvements in the HAZ.

APA, Harvard, Vancouver, ISO, and other styles

44

Han, Jixiong. "Processing Microstructure Evolution and Properties of Nanoscale Aluminum Alloys." University of Cincinnati / OhioLINK, 2005. http://rave.ohiolink.edu/etdc/view?acc_num=ucin1121701078.

Full text

APA, Harvard, Vancouver, ISO, and other styles

45

Delbin, Daniel. "Estudo da viabilidade de produção de esponjas da liga A2011 a partir do estado semi-solido." [s.n.], 2006. http://repositorio.unicamp.br/jspui/handle/REPOSIP/263622.

Full text

Abstract:

Orientador: Maria Helena Robert
Dissertação (mestrado) - Universidade Estadual de Campinas, Faculdade de Engenharia Mecanica
Made available in DSpace on 2018-11-08T18:37:47Z (GMT). No. of bitstreams: 1 Delbin_Daniel_M.pdf: 8551361 bytes, checksum: 770e9d00eeb959cc6e40cf3f314faa4e (MD5) Previous issue date: 2006
Resumo: Neste trabalho é estudada a viabilidade de produção de esponjas metálicas pela conformação de pasta tixotrópica da liga A2011, sobre camada de agente bloqueador (NaCl) posteriormente removido para formação da porosidade. Investiga-se a influência da temperatura de tratamento térmico, para obtenção da pasta semi-sólida, e da granulometria do agente bloqueador, na estrutura formada do material celular (aspecto geral, caracterização qualitativa e quantitativa dos poros, microestrutura da parede celular e densidade) e nas características de processo (forças de tixoforjamento e capacidade de penetração da pasta). São produzidos cilindros de material poroso metálico tipo sanduíche, compostos de camada porosa entre camadas maciças da liga, com três diferentes classes de porosidade: fina, média e grosseira. As esponjas foram submetidas à tomografia computadorizada e à análise metalográfica para sua caracterização estrutural. Os resultados obtidos mostram a viabilidade de obtenção de esponjas metálicas utilizando a tecnologia de semi-sólidos e o tipo de bloqueador utilizado. O sucesso do processo depende da fração líquida presente na pasta metálica tixotrópica, reduzida fração líquida pode resultar em incompleta infiltração e compressão das partículas do agente bloqueador. Nas condições analisadas a granulometria do agente bloqueador não teve influência sensível na qualidade do produto. A densidade do material poroso aumenta com o aumento da temperatura de processo, devido ao aumento da espessura de paredes metálicas na estrutura porosa
Abstract: The work analyses the possibility of the production of cellular material by pressing the A2011 alloy in the thixotropic semi-solid state, into a space holder pre-form. Space holder particles used are NaCl, which are removed from the product after the forming operation, resulting the porous material. It is investigated the influence of the thixoforming temperature and the size of space holder particles, in the structure of the obtained porous material (general aspect, quantitative and qualitative characterization of porosity, microstructure of cell walls and density of the product), as well as in the processing characteristics (required forces for infiltration, penetration ability of the slurry in the salt pre-form). Cylindrical samples, sandwich type, with a porous layer inserted between layers of compact alloy are produced, presenting three different ranges of porosity. The cellular material obtained contains opened porosity, being characterized as sponge. Products were analyzed by tomography and metallographic techniques. Results show that the proposed process is able to produce acceptable porous material, with a simple and low cost technique. The quality of the product depends rather on the processing temperature than on the size of space holder particles. Low liquid fraction in the thixotropic slurry can lead to incomplete infiltration and deformation of the pre-form. In the analyzed conditions, influence of the size of space holder particles could be observed neither in the processing ability nor in the quality of the product. Density of produced porous material increases as processing temperature increases, due to the increase of thickness of cell walls
Mestrado
Materiais e Processos de Fabricação
Mestre em Engenharia Mecânica

APA, Harvard, Vancouver, ISO, and other styles

46

Haase, Jake D. "Microbeam diffraction mapping of microtexture in Al-Li 2090 T8E41." Thesis, Georgia Institute of Technology, 1998. http://hdl.handle.net/1853/19586.

Full text

APA, Harvard, Vancouver, ISO, and other styles

47

PRASAD, PRASHANTH. "CHARACTERIZATION OF NEW, CAST, HIGH TEMPERATURE ALUMINUM ALLOYS FOR DIESEL ENGINE APPLICATIONS." University of Cincinnati / OhioLINK, 2006. http://rave.ohiolink.edu/etdc/view?acc_num=ucin1148315194.

Full text

APA, Harvard, Vancouver, ISO, and other styles

48

Blandford, Robert. "Characterization of fatigue crack propagation in AA 7075-T651." Master's thesis, Mississippi State : Mississippi State University, 2001. http://library.msstate.edu/etd/show.asp?etd=etd-04092001-152127.

Full text

APA, Harvard, Vancouver, ISO, and other styles

49

Cho, Jaeshin. "Effect of microstructure of aluminum alloys on the electromigration-limited reliability of VLSI interconnects." Thesis, Massachusetts Institute of Technology, 1990. http://hdl.handle.net/1721.1/13636.

Full text

APA, Harvard, Vancouver, ISO, and other styles

50

Maisano, Adam J. "Cryomilling of Aluminum-based and Magnesium-based Metal Powders." Thesis, Virginia Tech, 2006. http://hdl.handle.net/10919/31045.

Full text

Abstract:

Ball milling has been shown to produce nanostructures in metal powders through severe repetitive deformation. Ball milling at cryogenic temperatures (cryomilling) is more effective in this capacity due to the low temperature by slowing recovery and minimizing diffusion distances between different components. Nanostructured metals are of interest because of their unique physical and mechanical properties. The result of cryomilling is powder consisting of crystallites on the order of 30 â 50 nm. In order to characterize the properties of this material, it is often necessary to consolidate the powder, which is often difficult without causing significant grain growth. In this work, aluminum-rich and magnesium-rich alloys of varying composition are produced by cryomilling and characterized by x-ray diffraction. A novel consolidation process called high shear powder consolidation (HSPC) is used to densify as-received and as-milled powders with minimal growth. The construction of a cryomill, along with a modification for improving process yield, has provided a platform for the study of nanocrystalline metals. It has been shown that bulk nanocrystalline materials are attainable and that alloy composition influences mechanical properties.
Master of Science

APA, Harvard, Vancouver, ISO, and other styles

Dissertations / Theses on the topic 'Aluminum alloys. Aluminum Materials'

Create a spot-on reference in APA, MLA, Chicago, Harvard, and other styles