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Dissertations / Theses on the topic 'Iron-aluminium alloys'

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1

Coleman, Andrew John. "Filiform corrosion of aluminium alloys and iron." Thesis, Swansea University, 2007. https://cronfa.swan.ac.uk/Record/cronfa42908.

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2

Shollock, B. A. "Precipitation in rapidly solidified aluminium-chromium-iron alloys." Thesis, University of Oxford, 1989. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.238185.

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3

Hull, S. "Precipitation in aluminium based and iron based alloys." Thesis, University of Reading, 1985. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.370120.

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4

Hale, Geoffrey Eric. "The structure and properties of iron-manganese-aluminium alloys." Thesis, University of Leeds, 1985. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.434965.

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5

Humphreys, Elen Siobhain. "Production and characterisation of rapidly solidified Al-V-Fe alloys." Thesis, University of Oxford, 1999. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.302070.

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6

Deards, Nicola. "Recrystallisation nucleation and microtexture development in aluminium-iron rolled alloys." Thesis, University of Cambridge, 1992. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.259602.

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7

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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8

COUTO, ANTONIO A. "Influencia do teor de cromo e de tratamentos termicos na microestrutura e no comportamento mecanico de ligas intermetalicas ordenadas a base de Fesub3 Al." reponame:Repositório Institucional do IPEN, 1998. http://repositorio.ipen.br:8080/xmlui/handle/123456789/10701.

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IPEN/T
Instituto de Pesquisas Energeticas e Nucleares - IPEN/CNEN-SP
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9

Tash, Mahmoud. "Effect [sic] des paramètres métallurgiques sur le comportement d'usinage des alliages 356 et 319 (étude de forage et de taraudage) /." Thèse, Chicoutimi : Université du Québec à Chicoutimi, 2005. http://theses.uqac.ca.

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10

PAOLA, JEAN C. C. de. "Efeito de tratamentos termicos e da adicao de cromo nas propriedades mecanicas de ligas Fe-24 atAl." reponame:Repositório Institucional do IPEN, 1998. http://repositorio.ipen.br:8080/xmlui/handle/123456789/10664.

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IPEN/D
Instituto de Pesquisas Energeticas e Nucleares - IPEN/CNEN-SP
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11

Khalifa, Waleed. "Rôle des inclusions dans la germination de la phase a-aluminium des intermétalliques contenant du fer dans le coin riche en alumimium du système ternaire Al-Si-Fe /." Thèse, Chicoutimi : Université du Québec à Chicoutimi, 2003. http://theses.uqac.ca.

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12

PILLIS, MARINA F. "Estudo do comportamento de sulfetacao de ligas Fe20Cr." reponame:Repositório Institucional do IPEN, 2001. http://repositorio.ipen.br:8080/xmlui/handle/123456789/10925.

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IPEN/T
Instituto de Pesquisas Energeticas e Nucleares - IPEN/CNEN-SP
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13

Malavazi, Jefferson. "Caracterização microestrutural dos compostos intermetálicos e seu efeito no comportamento mecânico nas ligas de Al-9%Si com adições de Fe e Mn." Universidade de São Paulo, 2014. http://www.teses.usp.br/teses/disponiveis/85/85134/tde-17032014-151816/.

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O objetivo deste trabalho foi determinar a influência do ferro e do manganês em uma liga de alumínio com 9% de silício (% em peso). Para isto, foram elaboradas duas famílias de liga Al-9%Si: uma com os teores de 0,1%, 0,4%, 0,8% e 1,2% de Fe e uma segunda liga de Al-9%Si-0,8%Fe com teores de 0,1%, 0,4% e 0,7% de Mn. Para a realização deste estudo, foram produzidos corpos de prova de tração fundidos em coquilha, segundo a norma ASTM B108. Os corpos de prova obtidos foram tracionados para avaliação das propriedades mecânicas, em seguida, foram submetidos a uma análise microestrutural por microscopia óptica (MO) e eletrônica de varredura (MEV). As superfícies de fratura dos corpos de prova tracionados foram também observadas por MEV com a finalidade de comparar o efeito das adições de Fe e Mn. O efeito da adição crescente de Fe na liga Al-9%Si foi observado no ensaio de tração que mostrou queda tanto nos limites de resistência e de escoamento como no alongamento, decorrentes da formação da fase β-Al5FeSi que apresentou morfologia em plaquetas, interrompendo a continuidade da matriz de alumínio. Para teores abaixo de 0,4% de Fe, ocorreu um ligeiro aumento da resistência mecânica que pode ser atribuído à formação da fase α-Al8Fe2Si, que apresentou morfologia tipo escrita chinesa, que não interrompe a continuidade da matriz. Com adição de teores crescentes de Mn na liga Al-9%Si-0,8%Fe ocorreu uma elevação do limite de resistência e do alongamento, mas uma queda do limite de escoamento, quando comparados com a mesma liga sem adição de Mn. Conclui-se que esse comportamento pode ser atribuído a mudança de morfologia do intermetálico de plaquetas para escrita chinesa que intercala a matriz dúctil com a fase frágil, devido a adição do Mn.
This study aims to determine the influence of iron and manganese in an aluminum alloy with 9% silicon (% by weight). Were prepared two families of alloy Al-9%Si: one with the content of 0.1%, 0.4%, 0.8% and 1.2% Fe and a second alloy of Al-9% Si-0,8%Fe content of 0.1%, 0.4% and 0.7% Mn. For this study, tensile specimens were produced in permanent mold casting according to ASTM B108. The specimens obtained were pulled for quantitative evaluation of the mechanical properties and were subjected to a qualitative metallographic evaluation. Qualitative analysis of the bodies of tensile fracture test was conducted in order to compare the effect of additions of Fe and Mn. The effect of incremental addition of Fe in the alloy Al-9% Si was observed in the tensile test that showed a decrease in both the tensile and elongation flow as resulting from the formation of β-Al5FeSi phase platelet morphology showed that interrupting the continuity of aluminum matrix. To levels below 0.4% Fe, there was a slight increase in strength can be attributed to the formation of α-Al8Fe2Si phase morphology presented in chinese script that does not interrupt the continuity of the matrix. With addition of increasing concentrations of Mn in the alloy Al-9% Si-0, 8% Fe was an increase in the tensile strength and elongation but fall of yield stress when compared to the same alloy without Mn addition. We conclude that this behavior can be attributed to a change in morphology of the intermetallic platelets to chinese writing interspersing the ductile matrix with brittle phase due to the addition of Mn.
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14

Prajapati, Kamlesh. "Properties of magnetostrictive alloys at elevated temperatures." Thesis, University of Hull, 1995. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.322348.

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15

COELHO, RODRIGO E. "Obtencao das ligas Al-Fe-X-Si (X = V ou Nb) por moagem de alta energia e extrusao a quente." reponame:Repositório Institucional do IPEN, 2001. http://repositorio.ipen.br:8080/xmlui/handle/123456789/10870.

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Tese (Doutoramento)
IPEN/T
Instituto de Pesquisas Energeticas e Nucleares - IPEN/CNEN-SP
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16

Farhadi, Cheshmeh Morvari Gholamali. "Les effets des éléments de trace sur les caractéristiques des alliages de type 6XXX pour les applications automobiles /." Thèse, Chicoutimi : Université du Québec à Chicoutimi, 1999. http://theses.uqac.ca.

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17

Xu, Nan Materials Science &amp Engineering Faculty of Science UNSW. "Corrosion behaviour of aluminised steel and conventional alloys in simulated aluminium smelting cell environments." Awarded by:University of New South Wales. School of Materials Science & Engineering, 2002. http://handle.unsw.edu.au/1959.4/18760.

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Aluminium smelting is a high temperature electrometallurgical process, which suffers considerable inefficiencies in power utilization and equipment maintenance. Aluminium smelting cell works in the extreme environments that contain extraordinarily aggressive gases, such as HF, CO and SO2. Mild steel used as a structural material in the aluminium industry, can be catastrophically corroded or oxidized in these conditions. This project was mainly concerned with extending the lifetime of metal structures installed immediately above the aluminium smelting cells. An aluminium-rich coating was developed on low carbon steel A06 using pack cementation technique. Yttria (Y2O3) was also used to improve the corrosion resistance of coating. Kinetics of the coating formation were studied. XRD, FESEM and FIB were employed to investigate the phase constitution and the surface morphology. Together with other potentially competitive materials, aluminium-rich coating was evaluated in simulated plant environments. Results from the long time (up to 2500h) isothermal oxidation of materials at high temperature (800??C) in air showed that the oxidation resistance of coated A06 is close to that of stainless steel 304 and even better than SS304 in cyclic oxidation tests. Coated A06 was also found to have the best sulfidation resistance among the materials tested in the gas mixture contains SO2 at 800??C. Related kinetics and mechanisms were also studied. The superior corrosion resistance of the coated A06 is attributed to the slow growing alpha-Al2O3 formed. Low temperature corrosion tests were undertaken in the gas mixtures containing air, H2O, HCl and SO2 at 400??C. Together with SS304 and 253MA, coated A06 showed excellent corrosion resistance in all the conditions. The ranking of the top three materials for corrosion resistance is: 253MA, coated A06 and SS304. It is believed that aluminised A06 is an ideal and economical replacement material in the severe corrosive aluminium smelting cell environment.
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18

Smillie, Matthew John. "Casting and Analysis of Squeeze Cast Aluminium Silicon Eutectic Alloy." Thesis, University of Canterbury. Mechanical Engineering, 2006. http://hdl.handle.net/10092/1086.

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Squeeze casting is the practise of solidifying metals under mechanically applied pressure via a slow displacement of a die volume. It has been shown that squeeze casting enhances the mechanical properties of cast metals. Research into other high integrity casting processes has shown that using techniques that enhance melt quality can further increase the mechanical properties. Therefore a bottom-tapped, bottom-fed squeeze casting machine was designed and built around a pre-existing squeeze casting die designed for uniaxial pressure application. This was used to obtain quantitative metallurgical and microstructural information on the squeeze castings produced, including the effects of common micro-alloying additions of strontium modifier and titanium modifier on the microstructure and hardness of a commercial aluminium silicon eutectic alloy. These were examined using a Taguchi design of experiments approach. It was found that squeeze casting reduced porosity and secondary dendrite arm spacing and increased hardness, and reduced or eliminated increases in porosity and secondary dendrite arm spacing associated with micro-alloying addition. The size of possibly deleterious iron-rich precipitates was reduced, and the morphology of such precipitates changed to a possibly less deleterious form without further alloy additions of manganese. It was also found that melt control and handling is essential for consistent quality of castings in the production of small volume squeeze castings, such as the ones produced in this experimental work.
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19

Wang, Yun. "Solidification microstructure selection and coupled eutectic growth in Al-Fe and Al-Fe-Mn alloys." Thesis, University of Sheffield, 2000. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.324449.

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20

MALAVAZI, JEFFERSON. "Caracterização microestrutural dos compostos intermetálicos e seu efeito no comportamento mecânico nas ligas de Al-9%Si com adições de Fe e Mn." reponame:Repositório Institucional do IPEN, 2013. http://repositorio.ipen.br:8080/xmlui/handle/123456789/10554.

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Dissertação (Mestrado)
IPEN/D
Instituto de Pesquisas Energeticas e Nucleares - IPEN-CNEN/SP
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21

Castan, Christophe. "Etude de la recristallisation au cours du laminage a chaud d’aciers a basse densite fer-aluminium." Thesis, Saint-Etienne, EMSE, 2011. http://www.theses.fr/2011EMSE0629/document.

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Les directives de l'Union Européenne conditionnent la R&D du secteur automobile concernant l'utilisation de matériaux plus légers ayant pour but de réduire la consommation de carburant et une diminution de l’émission de gaz d’échappement. L’objectif est de mettre au point des aciers allégés d’au moins 10% (ρmax ≈ 7g/cm3). Les alliages fer-aluminium possèdent des propriétés physiques et mécaniques prometteuses mais présentent des défauts de surface appelés roping, apparaissant après l’emboutissage à froid. Cette étude a consisté à mieux comprendre les conditions de recristallisation au cours du laminage à chaud afin de contrôler la microstructure et ainsi limiter ces défauts. Il est généralement admis, lors d’une déformation à chaud, que les alliages ferritiques, à haute énergie de défaut d’empilement, donnent lieu aux processus de recristallisation dynamique géométrique (RDG) et de recristallisation dynamique continue (RDC). Dans cette étude, l’existence d’une transition entre les mécanismes de RDC et de recristallisation dynamique discontinue (RDD) a été mise en évidence pour des températures comprises entre 900 et 1100°C et des vitesses de déformation comprises entre 0,1 et 50s 1. La recristallisation post dynamique a aussi été étudiée afin d’observer l’évolution de la microstructure lors de maintiens en température. Un modèle développé antérieurement pour la RDC de l’aluminium a ensuite été utilisé afin de simuler une passe de laminage. Bien que la comparaison des résultats expérimentaux et simulés fasse apparaître un certain nombre de différences, ce modèle permet de reproduire qualitativement les évolutions de la microstructure
The instructions of the European Union pilot the R&D in the automotive industry regarding the use of lightweight materials which aims at reducing fuel consumption and emission of exhaust gases.The objective is to develop steels of density reduced by at least 10% (ρmax ≈ 7g/cm3). Iron aluminum alloys display promising physical and mechanical properties but they often exhibit surface defects, referred to as roping, appearing after the deep drawing process. This study was carried out to better understand the conditions of recrystallization during hot rolling to control the microstructure and thereby limit these defects.During hot deformation, it is generally agreed that geometric dynamic recrystallization (GDRX) and continuous dynamic recrystallization (CDRX) operate in ferritic alloys with high stacking fault energy. In this study, the existence of a transition between CDRX and the mechanism of discontinuous dynamic recrystallization (DDRX) has been brought into evidence in the temperature range 900 1100°C and strain rate range 0.1-50s-1. Post-dynamic recrystallization was also studied to observe the evolution of microstructure during holding temperatures.A model formerly developed for the CDRX of aluminum was then used to simulate a rolling pass. Comparison of computed and experimental results shows some differences but this model can reproduce microstructural changes qualitatively
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22

Delamare, José. "Etude microstructurale d'alliages Nd-Fe et Nd-Fe-Al : corrélation aux phases secondaires des aimants Nd-Fe-B." Rouen, 1992. http://www.theses.fr/1992ROUES058.

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La microstructure d'un alliage eutectique Nd-Fe a été étudiée grâce à la microscopie électronique à transmission. Il apparaît que le composé métastable A1 est constitué de deux composés nanocristallins, dont les compositions sont proches de Nd20Fe80 et Nd40Fe60 (% at. ). L'origine de la formation de tels composés est interprétée dans un diagramme de phases binaire métastable, incluant la phase NdFe2. Les caractéristiques structurales des autres phases du système binaire sont également étudiées. L'addition d'aluminium aux alliages Nd-Fe dont la composition est riche en Nd modifie drastiquement les propriétés macroscopiques (coercitivité, dureté). Ces effets sont liés aux modifications microstructurales apportées par l'aluminium (disparition de la phase A1 au profit de la phase ternaire U). La microstructure de ces alliages est voisine de celle de la phase intergranulaire rencontrée dans les aimants (Fe, Al)-Nd-B. Une étude bibliographique a confirmé que la phase U s'y présentait sous la forme de lamelles. Son influence sur la coercitivité des aimants est discutée. La structure cristalline polytypique de la phase U a été mise en évidence par diffraction électronique. Les polytypes 12R, 4H, 8H ont été identifiés. Une méthode permettant de déterminer les positions atomiques au sein de la maille polytypique est brièvement expliquée
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23

Fox, P. "The effect of minor additions on the oxidation of an iron-aluminium alloy." Thesis, University of Liverpool, 1986. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.480511.

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24

Buljac, Ante. "Compréhension, observation et quantification des mécanismes de rupture ductile par imagerie 3D." Thesis, Université Paris-Saclay (ComUE), 2017. http://www.theses.fr/2017SACLN036/document.

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Au cours des dernières décennies, des efforts importants ont été menés dans la modélisation des processus de rupture ductile entraînant des progrès substantiels. Cependant, la compréhension complète des mécanismes de rupture ductile dans des états de contraintes spécifiques demeure une question ouverte. Ceci est dû au manque de bases des données expérimentales et à la non validation des modèles pour ces conditions de chargement. Dans ce travail, les acquisitions de données sont principalement obtenues en utilisant la laminographie, ce qui rend possible l'imagerie de régions d'intérêt d'échantillons plats. L'utilisation d'éprouvettes larges (et minces) permet de générer différents états de contraintes et des conditions aux limites pertinentes pour l'ingénierie, qui ne pouvaient pas être évaluées jusqu'à présent en trois dimensions et en essais in-situ à des échelles micrométriques. La corrélation d'images volumiques (DVC) est utilisée pour mesurer les champs de déplacement à l'intérieur des échantillons en acquérant des images de laminographie 3D. Deux classes de matériaux représentatives de deux modes génériques de rupture ductile ont été examinées, à savoir les alliages d'aluminium (rupture par instabilité) et la fonte à graphite sphéroïdal (rupture par croissance de vide et coalescence).L'observation de la microstructure et les interactions déformations-endommagement pour différentes géométries d'échantillons et pour différents niveaux de triaxialité des contraintes associés ont été étudiées pour des alliages d'aluminium à une résolution micrométrique. De plus, un cadre combiné numérique-expérimental (DVC-FE) est introduit pour valider les simulations numériques à l'échelle microscopique pour la fonte à graphite sphéroïdal. Les simulations par éléments finis (FE), qui représentent la microstructure des matériaux étudiés, sont conduites avec des conditions aux limites de Dirichlet extraites des mesures DVC. Enfin, le cadre DVC-FE a été amélioré et utilisé comme une procédure d'identification intégrée pour l'étude du comportement élasto-plastique de la matrice ferritique de la fonte, non seulement en termes de champs cinématiques induits par la microstructure aléatoire, mais aussi avec les niveaux de charge globaux
In the last few decades significant efforts have been made in modeling ductile failure processes resulting in substantial progress. However, the full understanding of ductile failure mechanisms under specific stress states still remains an open question. This is partly due to missing experimental data and validation of models for such loading conditions.In this work, data acquisitions are mainly obtained by using laminography, which makes the imaging of regions of interest in flat samples possible. The use of large (and thin) specimens allows various stress states and engineering-relevant boundary conditions to be generated, which could not be assessed in three dimensions and in-situ at micrometer scales before. Digital Volume Correlation (DVC) is used for measuring displacement fields in the bulk of samples by registering 3D laminography images. Two material classes that are representative of two generic modes of ductile failure have been examined, namely, Al-alloys (failure by instability) and cast iron (failure by void growth and coalescence). The observation of microstructure and strain-damage interactions at micrometer resolution for various specimen geometries and associated levels of stress triaxiality are studied for Al-alloys. Additionally, a combined computational-experimental (DVC-FE) framework is introduced to validate numerical simulations at the microscopic scale for nodular graphite cast iron. Finite Element (FE) simulations, which account for the studied material microstructure, are driven by Dirichlet boundary conditions extracted from DVC measurements.Last, the DVC-FE framework is upgraded to an integrated identification procedure to probe elasto-plastic constitutive law of the cast iron ferritic matrix not only in terms of kinematic fields induced by the random microstructure but also by overall load levels
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25

FINCK, FRANCOISE. "Etude d'un nouveau systeme de depollution des gaz d'echappement automobile : modelisation par les techniques de surface." Université Louis Pasteur (Strasbourg) (1971-2008), 1988. http://www.theses.fr/1988STR13068.

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Etude portant sur un catalyseur pour epuration des gaz, compose de la phase catalytiquement active (surtout le palladium), du support d'impregnation (wash-coat d'alumine gamma) et du support mecanique (alliage fe-cr-al). Determination d'un mecanisme complet de formation de la couche de passivation d'alliages trimetalliques fe-cr-al
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26

Giroud, Franck. "Elaboration et études des propriétés de transport de couches minces quasicristallines AlCuFe." Université Joseph Fourier (Grenoble), 1998. http://www.theses.fr/1998GRE10251.

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Ce travail est consacre a l'elaboration, la caracterisation structurale et microstructurale, ainsi qu'a l'etude de la conductivite electrique de couches minces de l'alliage quasicristallin alcufe. Les echantillons ont ete fabriques par evaporation sequentielle des elements constitutifs de l'alliage, puis traitement thermique. Nous avons etudie les chemins reactionnels conduisant a la phase quasicristalline par diffraction des rayons x lors du traitement thermique de tricouches metalliques. La phase quasicristalline peut etre obtenue quelle que soit la sequence d'empilement du tricouche. Nous montrons que la premiere phase qui cristallise est al#2cu y compris lorsque la couche de fer est placee entre celles de al et cu. Dans ce cas on observe la formation d'alliages binaires al, cu de part et d'autre de la couche de fe, indiquant une diffusion croisee des deux elements al et cu a travers celle-ci. A plus haute temperature le fer participe aux reactions, s'alliant d'abord avec l'aluminium, avant que des phases ternaires n'apparaissent, qui conduisent ensuite au quasicristal. Nous nous sommes ensuite concentre sur l'elaboration de couches tres minces (jusqu'a 125 angstroms). Nous avons pu fabriquer des couches quasicristallines tres minces compactes et d'epaisseur homogene. Ainsi nous avons pu etudier la conductivite electrique des echantillons en fonction de leur epaisseur. A basse temperature, les dependances en temperature et en champ magnetique de la conductivite font apparaitre une transition vers un regime bidimensionnel, qui est une signature de la presence d'effets d'interferences quantiques. Cette etude confirme leur importance dans la conductivite des quasicristaux, et permet de preciser les valeurs des parametres microscopiques qui la regissent.
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27

Schwaller, Jean-Michel. "Etude et conception d'un support de catalyseur de post-combustion automobile a matrice metallique." Université Louis Pasteur (Strasbourg) (1971-2008), 1988. http://www.theses.fr/1988STR13070.

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Conception d'un pot catalytique et etude de l'efficacite de la catalyse. Mise au point d'un support metallique. Preparation du support par passivation de l'alliage fer-chrome-aluminium. Stabilisation de l'alumine par ajout de terres rares. Utilisation de platine et de palladium comme materiaux catalytiques
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28

Bodunrin, Michael Oluwatosin. "Hot deformation and corrosion behaviour of low-cost α+β titanium alloys with aluminium, vanadium and iron addictions." Thesis, 2018. https://hdl.handle.net/10539/26579.

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Abstract:
A thesis submitted to the Faculty of Engineering and the Built Environment in fulfilment of the requirements for the degree of Doctor of Philosophy in Metallurgical Engineering October, 2018
This thesis presents information on the development and processing of potentially low-cost α+β Ti-Al-V-Fe alloys. The major problem addressed in this research is the high cost of titanium and its alloys which have limited their widespread use since commercial production began in the 1950s. Two cost reducing research approaches: substitution of low-cost for expensive alloying elements, and the optimisation of hot working parameters were adopted in the development and processing of the low-cost Ti-Al-V-Fe alloys. In the first approach, two sets of low-cost alloys were developed based on the composition of commercial grade Ti-6Al-4V, the most utilised titanium alloy. The first set of alloys were designed by partial and full substitution of expensive vanadium with iron, a low-cost beta stabiliser, producing Ti-6Al-3V-1Fe, Ti-6Al-2V-2Fe, Ti-6Al-1V-3Fe and Ti-6Al-4Fe alloys. The second set of alloys was designed by both partial replacement of vanadium with iron and the reduction of aluminium content from 6 to 4.5 wt%, producing: Ti-4.5Al-3V-1Fe, Ti-4.5Al-2V-2Fe and Ti-4.5Al-1V-3Fe alloys. The influence of varying composition on the microstructure, hardness and corrosion behaviour was evaluated. Thermo-Calc software with the TTTi3 database was used to determine the phases present, their relative amounts and transformation temperatures under equilibrium conditions. The alloys were then produced by vacuum arc melting. The microstructure and hardness of as-cast samples and annealed samples of each alloy were evaluated. The results from the Thermo-Calc modelling showed that the beta transus temperature of the alloys reduced with increasing iron content while the volume fraction of the beta phase increased with increasing iron content. When compared to wrought Ti-6Al-4V alloy, the iron-containing alloys had a lower transus temperature but a higher volume fraction of beta phase. The annealed alloy showed a reduction in the volume fraction of beta phase since there was sufficient time for the beta-alpha transformation to take place during annealing. The hardness of iron-containing alloys increased with increasing iron content in both as-cast and annealed conditions. The hardness of the wrought Ti-6Al-4V alloy was lower than all the iron-containing low-cost alloys except Ti-4.5Al-3V-1Fe. The annealed samples were harder than the as-cast alloys. The increase in hardness was attributed to the Fe content, reduction in lath thickness and oxygen contamination during casting and heat treatment. The corrosion behaviour of the annealed iron-containing alloys were compared with the wrought Ti-6Al-4V alloy in solutions of sulphuric acid, sodium chloride and mixed sulphuric acid /sodium chloride. Open circuit potential and linear polarisation measurements were carried out. Ti-6Al- 1V-3Fe and Ti-4.5Al-1V-3Fe alloys had superior corrosion resistance to commercial Ti-6Al-4V in both sulphuric acid and sodium chloride solutions. Cost analysis on the low-cost alloys showed that about 7% ($175.6/100 kg) lower cost savings can be achieved by replacing 3 wt% V with Fe in Ti-6Al-4V. The advantage of cost with the improved hardness and corrosion resistance was used as a basis for selecting Ti-6Al-1V-3Fe and Ti-4.5Al-1V-3Fe for further work, i.e. optimisation of hot working parameters as the second cost reducing approach. In the second approach, the two selected experimental alloys were machined to rectangular samples and subjected to isothermal compression testing at varied temperatures (750 - 950°C) and strain rates (0.001 - 10 s-1) on a Gleeble 3500 thermomechanical simulator. The analysis of stress-strain curve and processing maps were used to determine the optimum processing condition during hot working. The activation energy for hot working of the alloys was determined using the hyperbolic-sine constitutive equation. The commercial grade Ti-6Al-4V alloy with a complex initial microstructure was also investigated. The flow curves exhibited distinct features under different deformation conditions. This indicated that flow behaviour is dependent on process variables such as strain rate, deformation temperatures, total strain and initial microstructures. Processing maps showed that the optimum processing conditions for the Ti-6Al-4V, Ti-4.5Al-1V-3Fe and Ti-6Al-1V-3Fe alloys were ~940°C/1 s-1, ~900°C/0.1 s-1 and ~900°C/0.01 s-1 respectively. Microstructural analysis revealed that the dominant softening mechanisms at the identified optimum processing conditions in both Ti-6Al-1V-3Fe and Ti-4.5Al-1V-3Fe alloys were dynamic recrystallisation of the prior beta grains and dynamic globularisation of the alpha phase respectively. Dynamic globularisation occurred much faster and easier in the lower aluminium alloy Ti-4.5Al-1V-3Fe (0.1 s-1) than in the Ti-6Al-1V-3Fe alloy (0.01 s-1). The activation energy for hot working of the alloys was higher in Ti-6Al-4V and Ti-6Al-1V-3Fe than in Ti-4.5Al-1V-3Fe. Some of the regions of instability were identified as ≥ 935°C/0.05 - 0.1 s-1 for Ti-6Al-4V, 750 - 780°C/1.2 - 10 s-1 for Ti-4.5Al-1V-3Fe and 750 - 870°C/0.9 - 10 s-1, Ti-6Al-1V-3Fe. The microstructures of the samples deformed in these regions revealed non-uniform deformation, voids and cracking as the unsafe softening mechanisms. These regions should be avoided when processing the alloys to save cost and prevent waste of materials.
E.R. 2019
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