Dissertations / Theses on the topic 'Fe₃Al'
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1
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.
2
Conrod, Kevin. "The hot working characteristics of Al-0.65% Fe, and Al-0.5% Fe-0.5% Co conductor alloys." Thesis, National Library of Canada = Bibliothèque nationale du Canada, 2000. http://www.collectionscanada.ca/obj/s4/f2/dsk1/tape4/PQDD_0021/MQ54324.pdf.
3
Устинова, Е. В., and Е. В. Суховая. "Структурообразование квазикристаллических сплавов Al–Ni–Fe." Thesis, Сумский государственный университет, 2015. http://essuir.sumdu.edu.ua/handle/123456789/40674.
Abstract:
Сплавы Al–Ni–Fe являются перспективными материалами, предназначенными для использования в агрессивных и окислительных средах. Особый интерес представляют эти сплавы в области образования квазикристаллической декагональной D-фазы, обладающей уникальными физико-механическими и физико-химическими характеристиками.
4
Payne, Matthew A. "High-throughput Screening of Alloy Oxidation Across Al-Fe-Ni and Al-Fe-Ni-Cr Composition Space." Research Showcase @ CMU, 2016. http://repository.cmu.edu/dissertations/863.
Abstract:
The high-temperature oxidation of multicomponent metal alloys involves complex kinetic processes that are not fully understood for many systems. As a result, prospective alloy compositions must typically be screened experimentally during the design of oxidation-resistant alloys. The comprehensiveness with which this can be done has conventionally been limited by the time required to prepare and test large numbers of single-composition alloy samples. This thesis describes the development, implementation, and assessment of a high-throughput methodology for studying the compositional dependence of alloy oxidation using composition spread alloy films (CSAFs), compact samples containing continuous, lateral gradients in composition. High-throughput analyses of the oxidation behavior of many different alloy compositions can be performed with a single CSAF by using spatially resolvable characterization techniques to probe different locations across its surface. We have used CSAFs to study the oxidation of aluminum-iron-nickel (Al-Fe-Ni) and aluminum-iron-nickel-chromium (Al-Fe-Ni-Cr) alloys. Given a minimum “critical Al concentration”, 𝑁Al∗, these alloys preferentially form a surface layer of Al2O3 upon initial exposure to an oxidizing environment, which provides substantial protection to the underlying metal against further oxidation. However, the value of 𝑁Al∗ can vary as a function of both multicomponent composition and the thermochemical identity of the oxidizing environment. By oxidizing CSAFs in dry or humid air at 427 °C, we have identified continuous boundaries through the Al-Fe-Ni and Al-Fe-Ni-Cr composition spaces where phenomenological transitions in oxidation behavior occur, including 𝑁Al∗ boundaries delineating the compositional limits for protective Al2O3 formation. The results demonstrate the potential of CSAF-based methods to screen with unprecedented detail the effects of composition on multicomponent alloy oxidation, and offer important fundamental insights into its mechanisms.
5
Луценко, Евгений Валентинович, and Анатолий Иванович Зубков. "Прочность и электропроводность вакуумных конденсатов Al-Fe." Thesis, Институт физики металлов им. М. Н. Михеева Уральского отделения Российской академии наук, 2013. http://repository.kpi.kharkov.ua/handle/KhPI-Press/14471.
6
Tathgar, Harsharn S. "Solubility of Nickel in Mg-Al, Mg-Al-Fe, and Mg-Al-Mn Systems." Doctoral thesis, Norwegian University of Science and Technology, Department of Materials Technology, 2001. http://urn.kb.se/resolve?urn=urn:nbn:no:ntnu:diva-2019.
Abstract:
The corrosion properties of magnesium alloys strongly depend on the alloy composition and impurities. Heavy elements like nickel, and iron have low solubility in solid magnesium. The dissolved elements in molten magnesium precipitate out on solidification and form intermetallic particles that are the cause of corrosion. Iron content should be kept below the standards specified by ASTM B94/94 using aluminium and manganese. Manganese forms intermetallic particles with iron and aluminium thereby lowering the solubility of iron, and these particles are cathodic compared to magnesium matrix. No method for the removal of nickel has been known previously. Dissolution was the only method to lower the nickel content. Published solubility data for nickel in pure magnesium is inconsistent and not available for magnesium alloys. Therefore various systems are studied to determine the behaviour of nickel in Mg-Al alloys. Methods for removal of nickel from Mg-Al alloys are also discussed.
7
Machado, Vagner de Oliveira. "Estudo das propriedades magnetostrictivas da liga (Fe0,80Al0,20)97B3 obtida por solidificação direcional." Universidade de São Paulo, 2014. http://www.teses.usp.br/teses/disponiveis/97/97134/tde-14092016-174334/.
Abstract:
Neste trabalho foram obtidas barras da liga (Fe0,80Al0,20)97B3 por solidificação direcional (SD), nos diâmetros de 3 e 4 mm, com o objetivo de melhorar a magnetostricção desse material através da introdução de textura. As etapas de produção das barras envolveram a fabricação de lingotes da liga por fusão a arco L1, L2 e L6, seguida de usinagem (U) ou forjamento rotativo (F) a quente. O maior comprimento de barra obtido foi de 50 mm. Através de microscopia eletrônica de varredura e análise de composição por espectroscopia de energia dispersiva, detectou-se a presença de boro nas amostras pela visualização do microconstituinte eutético formado da fase ? e da fase Fe2B. Resultados obtidos por difração de raios X indicam que a amostra da liga L1 para o diâmetro de 4 mm apresentou orientação preferencial nas direções , o que causou uma diminução expressiva da magnetostricção se comparada a da amostra do mesmo lingote para o diâmetro de 3 mm. Medidas de magnetização em função do campo magnético aplicado (Ha) indicaram que a magnetização de saturação das amostras que têm boro são em média 181 Am2/kg, sugerindo que as amostras tem ~ 2% de B. A barras obtidas por SD, tratadas termicamente (CTT) a 1100°C por 6 h, alcançaram uma maior magnetostricção (? = ?l/l), comparada as amostras sem tratamento térmico (STT), no qual o maior valor foi de 73 ? 10-6 na direção longitudinal da barra L1 forjada no diâmetro de 3 mm (L1F3-CTT). O maior fator de sensibilidade d?/dH obtido em função do comprimento da barra L1F3 foi de d?/dH = 0,9 x 10-9 m/A para a razão de aspecto ? = 12. Valor da constante anisotrópica K1 calculada a partir dos resultados experimentais se comparadas com dados da literatura, sugerem que em algumas amostras ocorre ordenamento parcial da fase cúbica da matriz, havendo assim a coexistência das fases Fe3Al (D03) e ?.In this work, bars of the alloy (Fe0,80Al0,20)97B3 were obtained by directional solidification (DS) in diameters of 3 and 4 mm, with the goal of improving the magnetostriction of the material through the introduction of texture. Production steps of the bars involved the manufacture of the alloy ingots, L1, L2, L6, by arc melting, then machining (M) or hot swaging (F). The greatest length that was achieved in a bar was 50 mm. The presence of boron in the samples was identified by scanning electron microscopy and energy dispersive spectroscopy, due to the presence of an eutectic microstructure that has dendrites and a microconstituent formed of phases ? and Fe2B. Results obtained by X-ray diffraction indicates that the bar L1 at the diameter of 4 mm showed preferential orientation in the directions , which caused a significant decrease of the magnetostriction compared to the same sample of the bar of diameter 3 mm. Magnetization measurements as a function of applied magnetic field (Ha) reveal that the saturation magnetization of the samples having boron is in average 181 Am2/kg, suggesting that the samples have ~ 2% of boron. The bars obtained by DS, thermally treated (CTT ) at 1100 ° C for 6 h, achieved higher magnetostrictions (? = ?l/l) compared to the samples without heat treatment.The highest value was 73 ? 10-6 was obtained in the longitudinal direction of the bar L1F in the diameter of 3 mm (L1F3-CTT). The maximum sensitivity factor d?/dH found as a function of the bars lengths was d?/dH = 0.9 x 10-9 m/A for an aspect ratio of ? = 12. Values of anisotropic constant K1, calculated using experimental results suggest that in some samples occur partial ordering of the cubic phase matrix , so there is the coexistence of phases Fe3Al ( D03 ) and ?.
8
Feitosa, Francisco Riccelly P. "Obtenção e evolução da fase icosaedral quasicristalina em ligas Al-Cu-Fe e Al-Cu-Fe-B por Melt-Spinnin." Universidade Federal da Paraíba, 2009. http://tede.biblioteca.ufpb.br:8080/handle/tede/5349.
Abstract:
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Melt spinnng processing is one of the most common processes to obtaining quasicrystaline structures. This is because of the fast cooling rate it imposes on the system, favoring such type of structure. This work deals with the production of quasycristaline phases (Al60Cu27,5Fe12,5 e Al57Cu27,5Fe12,5B3) via melt-spinning. The alloys were initially cast via induction melting under atmospheric air, with the designed chemical composition of the quasicrystals. Hence, the ribbons were produce by melt-spinning were characterized by means of x-ray diffraction and scanning electron microscopy. The results indicate that the icosahedral ψ - Al65Cu20Fe15 phase formed in both types of starting compositions. It seams that the boron contributes to stabilize the icosahedral phase.
O processo melt-spinning por imprimir altas taxas de resfriamento, é um dos principais meios para a obtenção de ligas com estrutura quasicristalinas, sendo o primeiro método utilizado para produzir materiais quasicristalinos. Neste trabalho utilizou-se este processo para a elaboração das ligas quasicristalinas Al(60-x)Cu25Fe15Bx, Al(60-x)Cu27,5Fe12,5Bx e Al(65-x)Cu20Fe15Bx (x=0 e x=3%at de boro). As ligas foram previamente fabricadas, por fusão, em atmosfera de argônio, em forno à indução, para em seguida serem submetidas ao processo melt-spinning , onde se obteve o material na forma de fita. As amostras foram caracterizadas por difração de raios-x e microscopia eletrônica de varredura. Os resultados indicaram a formação da fase icosaedral ψ - Al65Cu20Fe15 nas composições estudadas e uma provável contribuição do boro na produção dessa fase icosaedral
9
Beauchesne, Jean-Tristan. "Structures atomiques des phases icosaédriques de type F et dislocations." Phd thesis, Université Paris Sud - Paris XI, 2008. http://tel.archives-ouvertes.fr/tel-00274636.
Abstract:
Cette thèse est consacrée à l'étude des structures atomiques des phases icosaédriques de type F et leurs dislocations.Dans cette étude nous avons d'abord construit une structure générique permettant de traiter dans un seul schéma les phases icosaédriques de type F connues. Afin de valider ce modèle nous avons synthétisé quelques compositions suggérées par ce dernier. Ces synthèses ont permis entre autres de découvrir deux nouvelles phases quasipériodiques à la stoechiométrie Al66,08Cu21,35Mn8,29Fe4,28 , l'une icosaédrique (métastable) de type F et l'autre décagonale (stable). Elles ont montré, à une composition au-delà de celles déjà étudiées dans le système (Al,Pd,Fe), l'existence d'une phase F-IQC.
Globalement, ces résultats expérimentaux d'études de nouvelles phases icosaédriques ont permis de montrer la fiabilité du modèle : sur les trois essais de nouvelles compositions, deux ont montré l'existence de phases icosaédriques de type F et la troisième a mis en évidence une phase décagonale en relation d'épitaxie canonique avec la phase icosaédrique brut métastable (axe 10 confondu avec un axe 5).
Possédant un modèle fiable nous avons donc pu y introduire des dislocations. Nous avons ainsi précisé la géométrie des dislocations à l'échelle atomique, hors de la zone de cœur, dans les phases F-IQC. Dans cette structure nous avons aussi identifié les mouvements des phasons et tenté d'apporter des éléments de réponse aux mouvements de ces dislocations.
10
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.
Abstract:
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
11
Noetzel, Joachim. "Nanostruktur ionenbestrahlter Fe/Al- und Co/Cu-Grenzschichten." Doctoral thesis, Saechsische Landesbibliothek- Staats- und Universitaetsbibliothek Dresden, 2000. http://nbn-resolving.de/urn:nbn:de:swb:14-994414088062-09838.
Abstract:
In dieser Arbeit wird die nanoskalige Struktur von Grenzschichten in binären metallischen Multischichten untersucht. Ausgangspunkt sind laserdeponierte Multischichten des mischbaren Systems Fe/Al und des nichtmischbaren Systems Co/Cu. Die Struktur der durch die hochenergetischen Teilchen bei der Deposition entstandenen Grenzschichten wird mit Hilfe von zahlreichen Analyseverfahren (RBS, CEMS, EXAFS, Röntgenverfahren, TEM, AES und magnetische Messungen), sowie Simulationsrechnungen auf Basis des ballistischen Mischens (TRIDYN) untersucht. Anschließend wird mit Hilfe von Ionenstrahlmischen und thermischem Anlassen die Grenzschichtstruktur weiter modifiziert.
12
Temizel, Guvenc. "Intermetallic Phase Formation At Fe-al Film Interefaces." Master's thesis, METU, 2006. http://etd.lib.metu.edu.tr/upload/12607589/index.pdf.
Abstract:
This thesis presents the formation mechanism of intermetallics formed at Fe-Al film interfaces. Al thin films with different initial film thicknesses were coated on low carbon steel substrates by physical vapor deposition (PVD). By annealing the system at different temperatures and for different time intervals, several intermetallic phases were observed. X-Ray, SEM and EDS studies showed that intermetallic phases FeAl2 and Fe2Al5 are most dominant phases which were observed and they formed sequentially on the contrary of intermetallics which formed synchronous in bulk materials.
13
Луценко, Евгений Валентинович, В. В. Белозеров, and Анатолий Иванович Зубков. "Структура нано и микрокристаллических вакуумных конденсатов Al-Fe." Thesis, Институт физики металлов им. М. Н. Михеева Уральского отделения Российской академии наук, 2014. http://repository.kpi.kharkov.ua/handle/KhPI-Press/14394.
14
Dong, Chuang. "Structure et formation des quasicristaux et des phases cristallines approximantes dans les alliages Ti-Fe, Al-Cu-Fe(-Cr), Al-Cu-Co(-Si) et Al-Pd-Mn." Vandoeuvre-les-Nancy, INPL, 1991. http://docnum.univ-lorraine.fr/public/INPL_T_1991_DONG_C.pdf.
Abstract:
Nous avons analysé par microscopie électronique à transmission et par diffraction des neutrons les alliages quasicristallins suivants: Ti2Fe, Al65Cu20Fe15, Al71Pd19Mn10, Al65Cu20Fe10Cr5, Al65Cu17,5 et Al63Cu17,5Si2. Toutes ces études abordent deux aspects différents de ces alliages : les phases quasicristallines et leurs approximants cristallins. Dans le premier aspect, nous avons étudié la structure et la formation des phases icosaédriques Ti-Fe, Al-Cu-Fe et Al-Pd-Mn. Les mécanismes de croissance ont été identifiés. Les vitesses de croissance de ces quasicristaux sont très faibles par rapport à celles des cristaux. En ce qui concerne le deuxième aspect, nous nous sommes attachés à l'étude des approximants de la phase décagonale dans les alliages Al65Cu20Fe10Cr5 et Al63Cu17,5Co17,5Si2. Nous avons pu relier la phase décagonale à ses approximants en mettant en évidence les mêmes types d'unités structurales. Nous avons aussi mis l'accent sur la phase de type CsCl qui peut être la structure de base pour toutes les structures quasicristallines et cristallines étudiées dans ce travail
15
Ranganathan, Sathees. "Rapid solidification behaviour of Fe and Al based alloys." Doctoral thesis, KTH, Materialvetenskap, 2009. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-11325.
Abstract:
Rapid solidification experiment on Fe-Cr-Mo-Mn-Si-C alloy was performed to investigate metastable phases formed during the solidification. A wide range of cooling rate was used to analyse the sample from melt spinning technique (~107 K/s) to water quenching method (~102 K/s). A single phase featureless structure was obtaind initially in the melt spinning experiment for 77Fe-8Cr-6Mn-5Si-4C alloy. Reduction of C and addition of Mo led to form a complete featureless structure for 2.85 mm rod for 72.8Fe-8Cr-5Mo-6Mn-5Si-3.2C. Subsequent investigation of influence of Mo, Cr and Mn on the single phase featureless structure concludes that 7.5 mm thick complete featureless phase could be formed at 63.8Fe-15Cr-7Mo-6Mn-5Si-3.2C alloy composition. In a separate attempt, powder samples of 40 μm dia. size complete featureless powders were produced for three slightly different compostions for the same alloy system. Characterisation of the featureless phases reveals that it could be a single phase metastable structure of ε phase or austenitic solid solution with high amount of alloying element dissolved in it. Subsequent heat treatment of this featureless phase of the rod and the powder at different temperatures formed bainitic ferrite with fine carbides dispersed in the austenitic matrix. Hardness values measured on featureless phase found to have influenced by the alloying element specially Mo, Cr and Mn. In an attempet to improve clean melting condition to extend the featureless phase and to form amorphous, an elliptic short arc lamp vaccum furnace was designed with 10 kW lamp power. Around 30 g of iron based alloy system was melted and cast as a 7 mm rod sample in a copper mould. Design details of new mirror and the lamp furnace are presented. In a separate study, influence of the melt temperature on Al-Y and Al-Si alloys were investigated by levitaion casting in a silver mould at around 2000 K/s cooling rate. Plate like structure of Al8Y3 primary phase was observed at low melt temperature with small percentage of peritectic transformation of Al8Y3 and liquid melt into Al9Y2. A pre-dentritic star like crystal of Al3Y was observed in a fine eutectic matrix at very high melt temperature. Amount and number of primary Si crystals formed in a unit area during the solidification increases as the melt temperature increases.QC 20100805
16
Bazzi, Gessica Dias. "Estudo de revestimentos a base de ligas Fe-AL." reponame:Repositório Institucional da UFPR, 2012. http://hdl.handle.net/1884/26967.
Abstract:
Resumo: O crescente interesse pelo estudo dos intermetálicos vem de diversos motivos decorrentes do seu comportamento estável à altas temperaturas, que se soma à sua estabilidade química, atrativos que os tornam materiais muito competitivos para aplicações em temperaturas elevadas. Entre as ligas intermetálicas mais estudadas estão as ligas a base de Fe-Al, que oferecem excelente resistência à corrosão e à sulfatação, sem contar que elas mantém suas características em temperaturas mais elevadas (seu ordenamento é mantido muitas vezes até a temperatura de fusão) que as superligas utilizadas comercialmente. Avanços tecnológicos permitiram ultrapassar dificuldades de processamento dos intermetálicos a base de alumínio, mas ainda assim seu manuseio à temperatura ambiente é limitado, devido à baixa tenacidade característica que apresenta nessas condições. Este trabalho propõe o desenvolvimento de aluminetos de ferro como revestimentos processados pela técnica PTA, Plasma Transfered Arc (Plasma por Arco transferido) utilizando misturas de pós elementares de Fe e de Al . Pretende-se assim contornar dificuldades de manuseio de componentes fundidos com as ligas intermetálicas de Fe-Al. Estudou-se também o efeito da composição química do substrato e da presença de cromo, nióbio e carbeto de tungstênio nas misturas depositadas. Os revestimentos foram avaliados quanto à sua estabilidade à exposição em temperaturas de 400ºC e 600ºC. Resultados mostraram que há desenvolvimento de fases intermetálicas, FeAl e Fe3Al , nos revestimentos e que a escolha do substrato deve ser criteriosa, pois sua composição química altera as propriedades dos revestimentos, apesar de não ter sido observado o comprometimento do desenvolvimento dos intermetálicos. A adição de elementos de liga ou carbetos às misturas de pós depositadas altera as características dos revestimentos. A exposição à temperatura por até 12h mostrou que os revestimentos com melhor estabilidade foram aqueles processados com misturas de pós de Fe e de Al sem elementos de liga ou carbetos.
17
Stephen, Gail. "Al-Fe-Si intermetallics in 1000 series aluminum alloys." Thesis, McGill University, 1994. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=26424.
Abstract:
Iron and silicon are the major impurities in the 1000 series of wrought aluminum alloys. As the aluminum is recycled, it picks up more and more of these impurities which cannot economically be refined out of the aluminum. When the concentration of these impurities reaches a certain limit (maximum limit in 1000 series is 1 weight percent (Fe+Si)), the aluminum must be downgraded. The Fe and Si form brittle intermetallic phases in these alloys. The two main phases are the plate-like $ beta$-AlFeSi (Al$ sb5$FeSi) and $ alpha$-AlFeSi (Al$ sb8$Fe$ sb2$Si) which has a Chinese Script morphology. The mechanical properties of these alloys are believed to depend largely on the nature of these intermetallics.In the first part of this study, the conditions at which the intermetallics form, along with the ability of strontium to modify them were investigated. The second part consisted of determining how the morphology of the Al-Fe-Si phases affects the mechanical properties of the worked product. It was found that the formation of the Chinese Script morphology is promoted with increasing cooling rates, Fe/Si ratios and additions of strontium. However, the relative amount of Chinese Script was found to decrease with increasing (Fe+Si) levels. Tensile testing and formability testing (Erichsen ball punch deformation test) revealed that the presence of a Chinese Script morphology of Al-Fe-Si intermetallics (as opposed to the plate-like morphology) imparts no significant beneficial effect on the formability of the final rolled sheet.
18
Луценко, Евгений Валентинович, В. В. Белозеров, Анатолий Иванович Зубков, Галина Ивановна Зеленская, and А. А. Журбий. "Структура и физико-механические свойства вакуумных конденсатов Al-Fe." Thesis, Национальный научный центр "Харьковский физико-технический институт", 2014. http://repository.kpi.kharkov.ua/handle/KhPI-Press/14393.
19
Madel, Caroline. "Elektronische Transporteigenschaften von amorphem und quasikristallinem Al-Cu-Fe." [S.l. : s.n.], 2000. http://www.bsz-bw.de/cgi-bin/xvms.cgi?SWB9494963.
20
Maggs, Steven James. "Intermetallic phase selection in dilute Al-Fe-Si alloys." Thesis, University of Leeds, 1996. http://etheses.whiterose.ac.uk/4711/.
Abstract:
The DC casting of 1000 series AI-Fe-Si alloys often results in the formation of a defect known as the Fir Tree Zone (FI'Z) caused by variations in the type of binary AI-Fe eutectic intennetallic phase. These include AI3Fe, which is the equilibrium phase, and ~Fe, AImFe and AlxFe which are all common metastable phases found in DC cast ingots. Variation in the solidification conditions across a DC cast ingot.in particular, the cooling rate and local solidification velocity, bring about transitions from one intennetallic phase to another. The composition of the alloy, especially the presence of minor trace elements is also known to affect the transitions, but its effect has been less well studied. Equipment was constructed which reliably simulated DC casting conditions and enabled the FfZ to be reproduced. Experiments were conducted to examine the effect of the concentration of Fe, Si (and Fe:Si ratio) and of low levels «0.04 wt %) of Mg, Ti, Ti-B, V and Mn on the occurrence of phases causing the defect. Intennetallic phases extracted from the matrix by dissolution in hot butanol were identified by XRD. It was found that presence of Ti-B grain refmer had a large effect on the intennetallic phase selection, whilst the other trace element additions had lesser effects. In order to understand the way in which each element was affecting phase selection, experiments were conducted using DSC and a Bridgman furnace to isolate the variables of cooling rate and growth velocity respectively. A curve fitting technique was used to obtain values of eutectic nucleation onset temperature from DSC data where the primary aluminium and eutectic peaks overlapped. A technique was developed to extract intennetallic particles from DSC samples for examination in the TEM. It was found that the addition Ti-B grain refmer affected the phase selection by altering the nucleation temperature. The addition of Mg was found to stabilise the equilibrium phase by its affect on both growth temperature an nucleation temperature The effect of Ti was less clear in that it stabilised the equilibrium phase in the DSC experiments but tended to stabilise the metastable phase in the Bridgman experiments.
21
Wilhelmi, James. "Giant Non-Joulian Magnetostriction in Fe-Al Single Crystals." Master's thesis, Temple University Libraries, 2019. http://cdm16002.contentdm.oclc.org/cdm/ref/collection/p245801coll10/id/566535.
Abstract:
Mechanical EngineeringM.S.M.E.
A series of measurements aimed at comparing the magneto-elastic response and non-Joulian properties (magneto-volume) of single crystals of the iron-aluminum alloys Fe_81.8 Al_18.2 with different thermal treatments were per formed; the results of which confirmed net volume expansion in all field orientations. The magnitude of this expansion varied largely across various magnetic field alignments, with a greater than four times larger expansion for fields parallel to the [010] crystal axis than the [100] axis. The magnitude and direction of the change in volumetric expansion from quenched crystals to slow cooled crystals also depended heavily on the orientation of the magnetic field, with reduced magneto-volume responses ranging from ~2.4 to 0.5 times smaller for fields parallel to the [100] and [110] crystal axes respectively. These results present evidence of the non-Joulian effect and places crystals of the iron aluminum alloy Fe_81.8 Al_18.2 within the realm of functional non-Joulian magnets.
Temple University--Theses
22
Freitas, Augusto dos Santos. "Aplicação de campo efetivo e da técnica de Monte Carlo ao estudo de ligas Fe-Al." Universidade Federal de Sergipe, 2012. https://ri.ufs.br/handle/riufs/5352.
Abstract:
Coordenação de Aperfeiçoamento de Pessoal de Nível SuperiorIn the present work, we study the magnetic properties in the site diluted two-state Ising model on a body-centered cubic lattice. As an application of this study, we has been obtained the phase diagram for Fe-Al alloys and comparisons between theoretical model and experimental data are made by using the exchange interaction between Fe atoms in the alloy up to the third power dependence on concentration q of Al atoms. We have used the differential operator technique to expand the analytical expressions that arise from the diluted Ising model and describe such behavior by means of magnetic clusters with one and two spins. A good agreement between the theoretical model and experimental data is also obtained for both the magnetization and to the lattice parameter, r as a function of q. In this approach, it is shown as a good alternative to other analytical and computational techniques used for the study of diluted magnetic systems. The analytical results obtained for bcc lattice were compared with the Monte Carlo technique to determine the degree of applicability of the model and confirm the validity of the results obtained analytically.
Neste trabalho, aplicamos o modelo de Ising com diluição por sítios ao estudo das propriedades magnéticas de uma rede cúbica de corpo centrado (do inglês, body centered cubic, bcc), cujos sítios podem ser ocupados por spins. Como aplicação desse estudo, traçamos alguns diagramas de fase da liga Fe-Al, com comparações entre o modelo teórico utilizado e dados experimentais e propomos uma interação de troca entre os atomos de Fe, na liga, com dependência at´e terceira potência da concentração (q) de atomos de Al, possibilitando um melhor ajuste entre teoria e experimento para o diagrama T-q desta liga. Tomamos como base a t´ecnica do operador diferencial para expandir as express oes anal´ıticas que surgem do modelo de Ising dilu´ıdo e descrevemos tal comportamento magn´etico por meio de aglomerados com 1 e 2 spins. Um bom acordo entre o modelo te´orico proposto e dados experimentais tamb´em ´e obtido tanto para a magnetização como função de q quanto para o par ametro de rede, r, como função de q, sendo que esta abordagem mostra-se como uma boa alternativa a outras t´ecnicas anal´ıticas e computacionais utilizadas para o estudo de sistemas magn´eticos dilu´ıdos. Os resultados anal´ıticos obtidos para a rede bcc foram comparados com a t´ecnica de Monte Carlo para verificar o grau de aplicabilidade do modelo bem como confirmar a validade dos resultados encontrados analiticamente.
23
Kangouei, Navid. "Study of Equilibrium State in Fe-Mn-Al-C Alloys." Thesis, KTH, Termodynamisk modellering, 2014. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-148223.
Abstract:
We are living in a world of steel. Although there are a lot of other material in use, our most used material is steel. From building industry to transportation and even mother industries like mining, we use steel in different grades and amounts. There is always need for different grades of steel, and there is always interest in better properties and lower costs. Fe-Mn-Al-C steel group is one of the grades of steel is from the TWIP family. Beside its interesting mechanical properties, its corrosion resistance and cryogenic properties makes it very desirable to substitute more expensive current classes of the steel used in the industry. The automobile industry is also looking forward to implement this family of the steel in their products. This group of steel based on their chemical content can created a carbide ordered phase called κ which is one of the reasons of its interesting mechanical properties beside the TWIP properties. While κ may give more hardness due to precipitation hardening, it will make the steel brittle. Thus we need an understanding of the phase diagram of this group of the steels in order to choose our material and process accordingly. Phase diagrams are material engineers’ road maps for the processes and material choice as the initial steps, since we can predict the processes results and stable phases based on the equilibrium state from the diagrams. As the number of components gets more than three the phase diagram calculations and determination gets harder. For the ternary alloying systems we can only show sections of the phase diagrams as isothermal sections, or consider an element constant and depict the diagram as a “binary” system for the other two alloying elements at the other element concentration. In this work, we tried to experiment on the experimental data for equilibrium phases of Fe-Mn-Al-C alloying system based on the Equilibrated Alloys for alloys containing 20, 30 and 40 weight percent Manganese. The results were compared to the current database of the Thermo-Calc software for this family and we found some inconsistencies between the experimental data and the calculations which shows that the calculated results for this alloying system with its high Mn-content, is not reliable and that the thermodynamic descriptions must be adjusted.PrecHiMn (RFSR-CT-2010-00018)
24
Li, Xiaolin [Verfasser], Gerhard [Gutachter] Dehm, and Easo P. [Gutachter] George. "Al-rich Fe-Al based alloys / Xiaolin Li ; Gutachter: Gerhard Dehm, Easo P. George." Bochum : Ruhr-Universität Bochum, 2017. http://d-nb.info/1129452034/34.
25
Lens, Arnaud. "Mobilité des joints de grains dans les alliages Al-Mn et Al-Fe-Si." Saint-Etienne, EMSE, 2004. http://www.theses.fr/2004EMSE0004.
Abstract:
Pour simuler la recristallisation et la croissance des grains, nous avons étudié des mobilités expérimentales in-situ au MEB dans des alliages d'aluminium Al-Mn ainsi que des estimations théoriques de la vitesse de migration des joints de grains lors de recuits isothermes de 200 à 450ʿC. Pour réaliser cette étude, nous avons développé une technique de recuit in-situ au MEB/EBSD. Puis, nous avons analysé et comparé les résultats expérimentaux aux théories de traînages de solutés de Cahn, de Lücke et de Stüwe. Afin de vérifier quelques idées de Doherty, nous avons également examiné le développement de la croissance anormale dans l'Al-Fe-Si en présence de précipités. La présence d'une forte densité de sous-joints a été constatée en présence de croissance anormale. De plus, nous avons mesuré quelques valeurs de mobilités des joints de grains lors de la croissance normale et anormale de certains gros grains lors de recuits isothermes à 600ʿCExperimental grain boundary mobilities were studied with an in-situ SEM/EBSD technique in order to understand the recrystallization and grain growth processes in relevant, close to industrial Al-Mn alloys. Therefore, an in-situ technique was developed for annealing between 200°C to 450°C. Theoretical velocities estimated from the approaches of the solute drag theories of Cahn, Lucke and Stuwe were compared to the experimental results. Several Al-Fe-Si alloys were studied in order to validate some ideas of Doherty concerning abnormal grain growth in the presence of low angle grain boundaries and precipitates. Moreover, mobilities were measured during normal and abnormal grain growth at 600°C
26
Aviziotis, Ioannis. "Chemical vapor deposition of Al, Fe and of the Al13Fe4 approximant intermetallic phase : experiments and multiscale simulations." Thesis, Toulouse, INPT, 2016. http://www.theses.fr/2016INPT0100/document.
Abstract:
Des couches minces contenant des phases intermétalliques présent et des propriétés et de combinaisons de propriétés qui ne sont que partiellement explorées. Elles portent des solutions potentielles pour conférer des multifonctionnalités à des matériaux avancés requis par les secteurs industriels et sont source derupture et de l'innovation. Leur élaboration par dépôt chimique en phase vapeur à partir de précurseurs métallo-organiques (MOCVD) permet un dépôt conforme sur, et la fonctionnalisation de surfaces complexes, avec un temps de traitement court et à un coût modéré.Pour ceci, il est nécessaire de contrôler les réactions chimiques complexes et des mécanismes de transport impliqués. La modélisation informatique du procédé, alimentée avec des données obtenues par des expériences de dépôt ciblées, est un outil intégré pour l'étude et la compréhension des phénomènes qui se produisent à différentes échelles,de l’échelle macroscopique à celle nanométrique. La MOCVD de composés intermétalliques Al-Fe est étudiée en tant que paradigme de la mise en oeuvre d'une telle approche combinée, expérimentale et théorique. La phase approximanteAl13Fe4 est particulièrement ciblée,en raison de son intérêt comme alternative peu onéreuse aux catalyseurs à base de métaux noble dans l'industrie chimique. La mise au point du dépôt de la phase Al13Fe4est subordonnée à l'étude des proc /min à 185oC. La simulation du procédé prédit des vitesses de croissance en bon accord avec ces résultats, en particulier dans la gamme 139oC-227oC. La modélisation multi-échelle prédit la rugosité RMS avec précision, permettant ainsi le contrôle des propriétés telles que la résistivité électrique. La possibilité d'obtenir des films MOCVD de Fe à faible contamination en O et C est explorée dans la gamme 130oC-250oC à partir de fer pentacarbonyle, Fe(CO)5. La morphologie de la surface des films dépend fortement de la température de dépôt; elle devient plus lisse au-dessus de200oC, qui correspond aussi à la vitesse de croissance maximale, 60nm/min. La vitesse de dépôt diminue fortement lorsque la pression augmente. Les prédictions de la modélisation macroscopique reproduisent précisément ce comportement. Elles indiquent que la diminution de la vitesse de croissance à des températures et des pressions élevées est due à l’augmentation de la décomposition du précurseur en phase gazeuse et à l'inhibition de la réactivité de surface par le ligand CO. Le modèle multi échelle conduit à des valeurs RMS en bon accord avec les mesures expérimentales, en particulier à des températures plus élevées. Suite à l’étude des deux procédés, des co-dépôts d'Al-Fe effectués à 200oCrésultent en des films riches en Alavec une microstructure poreuse et rugueuse. Ceux-ci ne contiennent pas de phases intermétalliques et sont riches en oxygène dû à la réaction d'Al avec les ligandscarbonyles. Afin d’éliminer la contamination, des dépôts séquentiels d'Al et de Fe sont réalisés, ce dernier dans des conditions modifiées à 140oC, 40Torr et 10 min. Ces films sont exemptes d’hétéroélements et présentent un rapport atomique Al:Fe13:4. Diffraction des rayons X et microscopies électroniques révèlent qu’un recuit in situ à 575oC pendant 1 h conduit à des films à gradient de la composition sur l'épaisseur,composés de la phase approximantem-Al13Fe4 conjointement avec des phases intermétalliques Al-Fesecondaires. Il est ainsi démontré que des procédés MOCVD sont appropriés pour obtenir des films constitués d'alliages intermétalliques.Ces films multifonctionnels,appliqués de façon conforme sur des surfaces complexes sont utiles pour un grand nombre d'applicationsFilms containing intermetallic compounds exhibit properties and combination of properties which are only partially explored. They carry potential solutions to confer multifunctionality to advanced materials required by industrial sectors and to become a source of breakthrough and innovation.Metalorganic chemical vapor deposition (MOCVD) potentially allows conformal deposition on, and functionalization of complex surfaces, with high throughput and moderate cost. For this reason, it is necessary to control the complex chemical reactions and the transport mechanisms involved in a MOCVD process. In this perspective, computational modeling of the process, fed with experimental information from targeted deposition experiments, provides an integrated tool for the investigation and the understanding of the phenomena occurring at different length scales, from the macro- to the nanoscale. The MOCVD of Al-Fe intermetallic compounds is investigated in the present thesis as a paradigm of implementation of such a combined, experimental and theoretical approach. Processing of the approximant phase Al13Fe4 is particularly targeted, due to its potential interest as low-cost and environmentally benign alternative to noble metal catalysts in the chemical industry. The attainment of the targeted Al13Fe4 intermetallic phase passes through the investigation of the MOCVD of unary Al and Fe films. The MOCVD of Al from dimethylethylamine alane (DMEAA) in the range 139oC-241oC results in pure films. Increase of the deposition temperature yields higher film density and decreased roughness. The Aldeposition rate increases to a maximum of 15.5 nm/min at 185oC and then decreases. Macroscopic simulations of the process predictdeposition rates in sufficient agreement with experimental measurements, especially in the range 139oC-227oC. At higher temperatures, competitive gas phase and surface phenomena cannot be captured by the applied model. Multiscale modeling of the process predicts the RMS roughness of the films accurately, thus allowing the control of properties such as electrical resistivity which depend on the microstructure. The MOCVD of Fe from iron pentacarbonyl, Fe(CO)5, is investigated in the range 130oC-250oC for the possibility toobtain fairly pure Fe films with low Oand C contamination. The surface morphology depends strongly on the temperature and changes are observed above 200oC. The Fe deposition rate increases up to 200oC, to a maximum of 60 nm/min, and then decreases. Moreover, the deposition rate decreases sharply with increasing pressure. Computational predictions capture accurately the experimental behavior and they reveal that the decrease athigher temperatures and pressures is attributed to the high gas phase decomposition rate of the precursor and to inhibition of the surface fromCO. The multiscale model calculates RMS roughness in good agreement with experimental data, especially at higher temperatures. Upon investigation of the two processes, aseries of Al-Fe co-depositions performed at 200oC results in Al-rich films with a loose microstructure. They contain no intermetallic phases and they are O-contaminated due to the reaction of the Al with the carbonyl ligands. Sequential deposition of Al and Fe followed by in situ annealing at 575oC for 1 h is applied to bypass the Ocontamination. The process conditions of Fe are modified to 140oC, 40 Torr and 10 min resulting in O-free films with Al:Fe atomic ratio close to the targeted 13:4 one. Characterization techniques including X-ray diffraction, TEM and
27
Kumar, Golden. "Structural and magnetic characterization of Nd-based Nd-Fe and Nd-Fe-Co-Al metastable alloys." Doctoral thesis, Saechsische Landesbibliothek- Staats- und Universitaetsbibliothek Dresden, 2005. http://nbn-resolving.de/urn:nbn:de:swb:14-1118153436094-69139.
Abstract:
The aim of the present work is to characterize a metastable hard magnetic phase referred to as "A1" in Nd-Fe alloys, which forms as a part of the fine eutectic depending on the composition and cooling rate. In order to define the range of composition for the formation of A1, Nd100-xFex (x = 20, 25, 40) alloys are cooled at about 150 K/s. The results indicate that for a cooling rate of 150 K/s, the hypereutectic Nd100-xFex (x = 20) alloys solidify into hard magnetic A1 whilst the hypoeutectic alloys (x = 40) show the formation of Nd2Fe17 crystallites. However, no sample cooled at 150 K/s shows the peaks of Nd5Fe17 as expected from the equilibrium Nd-Fe phase diagram. The effect of cooling rate on the formation of hard magnetic A1 is studied by investigating the Nd80Fe20 alloys cooled at different rates. The microstructure of hard magnetic Nd80Fe20 alloys displays a fine eutectic-like matrix consisting of Nd-richer and Fe-richer regions. The Nd-richer regions are identified as dhcp Nd and fcc Nd-Fe solid solution. However, the Fe-richer regions also referred to as A1, are diffuse and give an average composition of Nd56Fe44. These regions yield complex electron diffraction patterns, which do not match with any known Nd-Fe phase. HRTEM images of the Fe-richer regions reveal the presence of 5-10 nm crystallites embedded in an amorphous phase. Thus the Fe-richer regions of the hard magnetic Nd80Fe20 specimens are not a single homogeneous phase rather they are mixture of finely dispersed nanocrystallites in an amorphous phase. The demagnetization curves the hard magnetic Nd80Fe20 measured at temperatures above 30 K are typical of a hard magnetic material. The coercivity increases from 0.48 to 4.4 T with the temperature decreasing from 300 to 55 K. The demagnetization curves change from single to two-phase type when the temperature approaches 29 K, ordering temperature of fcc Nd-Fe solid solution. The measurements of initial magnetization, field dependence of coercivity, and temperature dependence of coercivity suggest the Stoner-Wohlfarth type magnetization reversal process for the hard magnetic A1. The values of anisotropy constant are estimated by fitting the magnetization data to the law-of-approach to saturation. The temperature dependence of anisotropy constant and the coercivity indicate that the origin of coercivity is magnetic anisotropy. A cluster model with sperimagnetic arrangement of Nd and Fe spins is used to explain the hard magnetic behavior of the mold-cast Nd80Fe20. Structural and magnetic properties of multicomponent Nd60Co30-xFexAl10 (0 < x < 30) alloys are compared with the binary Nd-Fe alloys. Magnetic measurements of the multicomponent alloys show that the magnetic properties are controlled by the fraction of the Fe content. The coercivity of the Nd60Co30-xFexAl10 mold-cast rods does not vary much with the Fe-content for more than 10 at.% Fe but the remanence and the maximum magnetization increase linearly with the Fe content. The temperature dependence of coercivity, effective anisotropy constant, and anisotropy field are identical to those for the binary Nd80Fe20 mold-cast rod. These results clearly suggest that the binary Nd80Fe20 and the multicomponent Nd60Co30-xFexAl10 (x > 5) mold-cast rods are magnetically identical.
28
Ferguson, David Bruce. "Characterization of high damping Fe-Cr-Mo and Fe-Cr-Al alloys for naval ships application." Thesis, Monterey, California. Naval Postgraduate School, 1988. http://hdl.handle.net/10945/22942.
Abstract:
The metallurgical basis for high damping in Fe-Cr-based alloys was investigated. Two alloys similar to VACROSIL-010 were studied, with compositions of 84.7 Fe-11.44 Cr-2.91 A1 and 84.8 Fe-11.65 Cr-2.92 Mo. The strain dependence of specific damping capacity (SDC) was evaluated using a modified version of the resonant dwell technique. Heat treatment variations were introduced by annealing in argon gas at temperatures between 950 C and 1100 C and then furnace cooling. Cantilever beam specimens were evaluated for SDC at their first three resonant modes (0-1,000 Hz) at room temperature. Changes in damping capacity were correlated with the results of tensile hysteresis testing and dilatometry. Keywords: Damping; Ship silencing; Ferritic stainless steels
29
Kumar, Golden. "Structural and magnetic characterization of Nd-based Nd-Fe and Nd-Fe-Co-Al metastable alloys." Doctoral thesis, Technische Universität Dresden, 2004. https://tud.qucosa.de/id/qucosa%3A24505.
Abstract:
The aim of the present work is to characterize a metastable hard magnetic phase referred to as "A1" in Nd-Fe alloys, which forms as a part of the fine eutectic depending on the composition and cooling rate. In order to define the range of composition for the formation of A1, Nd100-xFex (x = 20, 25, 40) alloys are cooled at about 150 K/s. The results indicate that for a cooling rate of 150 K/s, the hypereutectic Nd100-xFex (x = 20) alloys solidify into hard magnetic A1 whilst the hypoeutectic alloys (x = 40) show the formation of Nd2Fe17 crystallites. However, no sample cooled at 150 K/s shows the peaks of Nd5Fe17 as expected from the equilibrium Nd-Fe phase diagram. The effect of cooling rate on the formation of hard magnetic A1 is studied by investigating the Nd80Fe20 alloys cooled at different rates. The microstructure of hard magnetic Nd80Fe20 alloys displays a fine eutectic-like matrix consisting of Nd-richer and Fe-richer regions. The Nd-richer regions are identified as dhcp Nd and fcc Nd-Fe solid solution. However, the Fe-richer regions also referred to as A1, are diffuse and give an average composition of Nd56Fe44. These regions yield complex electron diffraction patterns, which do not match with any known Nd-Fe phase. HRTEM images of the Fe-richer regions reveal the presence of 5-10 nm crystallites embedded in an amorphous phase. Thus the Fe-richer regions of the hard magnetic Nd80Fe20 specimens are not a single homogeneous phase rather they are mixture of finely dispersed nanocrystallites in an amorphous phase. The demagnetization curves the hard magnetic Nd80Fe20 measured at temperatures above 30 K are typical of a hard magnetic material. The coercivity increases from 0.48 to 4.4 T with the temperature decreasing from 300 to 55 K. The demagnetization curves change from single to two-phase type when the temperature approaches 29 K, ordering temperature of fcc Nd-Fe solid solution. The measurements of initial magnetization, field dependence of coercivity, and temperature dependence of coercivity suggest the Stoner-Wohlfarth type magnetization reversal process for the hard magnetic A1. The values of anisotropy constant are estimated by fitting the magnetization data to the law-of-approach to saturation. The temperature dependence of anisotropy constant and the coercivity indicate that the origin of coercivity is magnetic anisotropy. A cluster model with sperimagnetic arrangement of Nd and Fe spins is used to explain the hard magnetic behavior of the mold-cast Nd80Fe20. Structural and magnetic properties of multicomponent Nd60Co30-xFexAl10 (0 < x < 30) alloys are compared with the binary Nd-Fe alloys. Magnetic measurements of the multicomponent alloys show that the magnetic properties are controlled by the fraction of the Fe content. The coercivity of the Nd60Co30-xFexAl10 mold-cast rods does not vary much with the Fe-content for more than 10 at.% Fe but the remanence and the maximum magnetization increase linearly with the Fe content. The temperature dependence of coercivity, effective anisotropy constant, and anisotropy field are identical to those for the binary Nd80Fe20 mold-cast rod. These results clearly suggest that the binary Nd80Fe20 and the multicomponent Nd60Co30-xFexAl10 (x > 5) mold-cast rods are magnetically identical.
30
Ducher, Roland. "Contribution à l'étude du diagramme de phase ternaire Fe-Ti-Al et des équilibres Fe-TiAl." Toulouse, INPT, 2003. http://www.theses.fr/2003INPT005G.
Abstract:
La première partie de ce travail a porté sur l'étude ce couples de diffusion élaborés à 1200°C et associant des alliages de TiAl à des éléments base-Fe, un acier doux et des alliages riches en fer du système Al-Fe-Ti. Dans tous les cas observés, la zone d'interdiffusion présente des composés intermétalliques appartenant au diagramme de phase du système ternaire AL-Fe-TI. La nature des différentes réactions se produisant dans les zones d'interdiffusion a été caractérisée par microscopie électronique à balayage et analyse chimique par specrométrie à dispersion d'énergie. Le système ternaire Al-Fe-Ti ayant été peu étudié pour les températures supérieures à 1000°C, nous avons été amené à entreprendre une étude expérimentale destinée à compléter les données concernant le liquidus et les équilibres entre phases entre le liquidus et l'isotherme 1000°C. Cette étude a porté sur une trentaine d'alliages, couvrant l'ensemble du diagramme ternaire, qui ont été caractérisés par diffraction des rayons X (RX), analyse termique différentielle (ATD), MEB, EDS. Cette partie de l'étude a permis de proposer plusieurs modifications notables de la seule projection de liquidus antérieurement publiée (en 1980). La microscopie électronique en transmission (MET) a été employée en complément des techniques précédentes, en particulier pour aider à la caractérisation de la microstructure de certains alliages. Les résultats obtenus pendant ce travail sont discutés et confrontés à ceux de la littérature dans la discussion générale à l'issue de laquelle une représentation de la section isotherme 1200°C du diagramme Al-Fe-Ti est proposée.
31
Taravel, Condat Carol. "Influence des conditions d'élaboration sur la microstructure de solidification lors de la trempe sur roue d'alliages Fe₇₅Al₂₅ et Fe₍₇₅-ₓ₎Al₂₅Bₓ₍₀, ₀₅₋₁₎ (pds%)." Grenoble INPG, 1991. http://www.theses.fr/1991INPG0106.
Abstract:
Les mécanismes de solidification dans les alliages Fe#7#5Al#2#5 et Fe#7#5#-#xAl#2#5B#x#(#0#,#0#5#-#1#) (pds%) élaborés par trempe de coulée plane sur roue sont analyses, nous dégageons l'influence des paramètres d'élaboration sur la microstructure finale des rubans (taille et forme des grains, structure dendritique, texture). Les structures de solidifications sont interprétées a l'aide d'un modèle thermique simulant le refroidissement et la solidification des alliages Fe#7#5Al#2#5 dans la flaque; entre autre, nous étudions avec précision les contributions du coefficient de transfert thermique sur la germination, la recalescence, et la déstabilisation du front de solidification. Par ailleurs, des mesures pyrométriques réalisées a la surface des rubans pendant la trempe ainsi qu'une étude de recuits a hautes températures, expliquent l'influence de l'atmosphère sur la microstructure finale des rubans, les rubans élaborés sous vide subissant une importante croissance des grains a l'état solide dans l'atmosphère de trempe des leur décollement de la roue. De façon générale, les rubans présentent une zone de grains equiaxes cote roue surmontée d'une couche de grains colonnaires débouchant cote libre. L'épaisseur de la zone équiaxe par rapport a celle de la zone colonnaire augmente avec l'épaisseur du ruban et diminue quand on rajoute du bore. Ces résultats sont discutes a l'aide du modèle théorique
32
Bauer, Birgitta. "Einkristallzüchtung und Charakterisierung Al-reicher komplexer metallischer Phasen in Al-Cr-Fe und benachbarten Systemen." Diss., lmu, 2010. http://nbn-resolving.de/urn:nbn:de:bvb:19-120188.
33
El, Kabir Tarik. "Etude de matériaux composites à matrice base Al renforcés par des particules Al-Cu-Fe." Poitiers, 2007. http://www.theses.fr/2007POIT2342.
Abstract:
Les matériaux quasicristallins (QC) présentent des propriétés mécaniques intéressantes, telles une dureté et un module d’Young élevés, ce qui en fait de bons candidats en tant que renforts pour les matériaux composites à matrices métalliques. Ce travail a pour but l’élaboration et l’étude des microstructures et propriétés mécaniques de matériaux composites à base Al renforcés par des particules QC. Des composites à matrice Al3Mg2, Al, Al-Cu-Mg et Al-Mg-Si renforcés par 50% vol. De particules QC Al-Cu-Fe ont été élaborés par infiltration sous pression de gaz. Les composites obtenus sont complexes et présentent de nombreuses phases résultant de la diffusion de l’aluminium et du cuivre. Ces composites sont caractérisés par des contraintes d’écoulement élevées et une fissuration précoce, quelle que soit la température de déformation. Deux composites à matrice aluminium renforcés par des particules QC ont été élaborés par compression isostatique à chaud (HIP). En fonction de la température d’élaboration, nous avons obtenu des matériaux biphasés, l’un renforcé par des particules tétragonales w-Al-Cu-Fe et l’autre par des particules i-Al-Cu-Fe. Ces matériaux présentent des propriétés mécaniques améliorées par rapport à la matrice seule. La forte dépendance de s0. 2% en température observée dans le composite Al/w suggère que la déformation plastique est contrôlée par des mécanismes thermiquement activés. En revanche, pour le composite Al/i, la contribution des contraintes internes au durcissement du composite est à prendre en compte en plus des mécanismes thermiquement activésQuasicrystalline (QC) materials exhibit remarkable mechanical properties at low and intermediate temperatures, such as high hardness together with high elastic modulus. One of the potential applications of QC materials is to use them as the reinforcement phase of composite materials. This study reports about processing, microstructures and mechanical properties of Al-based metal matrix composites (MMC) reinforced by QC particles. Five Al-based MMC were produced using the gas pressure infiltration technique. Al3Mg2, Al, Al-Cu-Mg and Al-Mg-Si matrices were used. They were reinforced by 50 % vol. Fraction of Al-Cu-Fe QC particles. The as-produced composites are rather complex and various phases are formed during the production process. These phases were identified to result from diffusion of both the aluminium and the copper. These composites are characterised by high flow stresses, that are unfortunately accompanied by numerous cracks whatever the temperature deformation. Two composites with an Al matrix initially reinforced by QC particles were prepared by hot isostatic pressing (HIP). With this technique two-phase composites are obtained, but depending on the processing temperature, the reinforcement particles are either of i-phase or !-phase. It is observed that ! particles contribute more positively to the improvement of the mechanical properties than the QC particles. The temperature dependences of "0. 2% suggest that the plastic deformation of the composite Al/!-Al-Cu-Fe is controlled by thermally activated mechanisms. In the composite Al/i-Al-Cu-Fe, in addition to thermally activated mechanism, the contribution of the internal stresses to the hardening of the composite must be taken into account
34
Krawczyk, Jacek. "Otrzymywanie oraz charakterystyka kompozytów typu kryształ - kwazikryształ stopów Al-Cu-Fe i Al-Cu-Co." Doctoral thesis, Katowice : Uniwersytet Śląski, 2011. http://hdl.handle.net/20.500.12128/5298.
Abstract:
In this work was concluded that it is possible to obtain stable in situ composites of Al-Cu-Fe and Al-Cu-Co alloys with reinforcement containing quasicrystalline phases by the mIFC and Bridgman methods. The chemical compositions and technological parameters of processes for which it is possible to obtain stable CQ composites were determined. The composites morphology (especially reinforcement morphology) was examined for different parameters of obtaining process. The materials for investigations were obtained in several stages using two different methods: the Bridgman method and the modified Inclined Front Crystallization (mIFC) method. In the first stage initial composition was chosen based on the Al-Cu-Fe and Al-Cu-Co equilibrium diagram. The composite was studied using X-ray and electron diffraction, light-optical and scanning electron microscopy, X-ray topography and Laue diffraction. Specially prepared composite samples were subjected to uniaxial tension tests using a tensile testing machine in static conditions. Chemical microanalysis was performed using scanning
electron microscope, equipped with an energy dispersive X-ray spectroscope. Using lightoptical
and scanning electron microscopes the morphology of reinforcement was specified.
Based on the results of investigations, it was assumed that the composites of Al-Cu-Fe alloys have a reinforcement in the form of fibres with a rhomboidal cross-section, growing paralel to the solidification direction. In the case of composites based on Al-Cu-Co alloys, fibres have an irregular shape in cross-section and grow at some angle to the solidification direction. Both types of reinforcement include the quasicrystalline phase, respectively: icosahedral i-phase and decagonal D-phase. The fiber growth model was developed based on the redistribution of Aluminum concentration in the diffusion area on solidification front. Laue examination
showed the presence of single-crystalline phase in the composite. This phase was the matrix
of the composites. For some parameters of the Bridgman process, two-scale composites of Al-Cu-Co alloy were obtained. Such composites are characterized by two types of reinforcement with different scales of fiber diameters: nano-scale and micro-scale. The specimens were studied by the X-ray topography during uniaxial tension tests. CQ composites in the uniaxial tension test fractured by brittle mechanism.
35
KANDEL, LAURENT. "Etude des proprietes magnetiques et electroniques des phases quasicristallines al-mn et al-cu-fe." Paris 11, 1992. http://www.theses.fr/1992PA112281.
Abstract:
Une etude systematique en susceptibilite a. C. Et aimantation des phases icosaedriques a173mn21si6 et decagonales a180mn20, ou le mn a ete substitue par un melange equiatomique fe-cr, a permis de montrer que l'origine du magnetisme inhomogene observe dans les phases icosaedriques, est liee a l'existence de site de mn isoles. La phase decagonale a un comportement different, puisque la fraction de mn magnetiques est proportionnelle a la concentration en mn. Les atomes de mn observes par rmn ne sont pas dans un schema d'etat lie virtuel et presentent une forte hybridation s-p sur le site de l'al. Il faut donc faire l'hypothese de trois types d'etat du mn pour expliquer les proprietes physiques de ces phases. Une etude par rmn des phases quasicristallines al-cu-fe, ne montre aucune influence de l'etat metallurgique sur les proprietes electroniques. De plus, on observe une forte hybridation s-p par rapport a l'al metal. Nous avons egalement mis en evidence par des mesures d'aimantation, que tous les echantillons d'al-cu-fe sont diamagnetiques, mais qu'une composante ferromagnetique peut apparaitre aleatoirement, sans correlation avec l'etat metallurgique
36
Laplanche, Guillaume. "Synthèse et caractérisation de la phase ω-Al7Cu2Fe et de composites Al/Al-Cu-Fe." Poitiers, 2011. http://nuxeo.edel.univ-poitiers.fr/nuxeo/site/esupversions/f121f0d6-5db1-44cc-9ee3-bbc6f5c3ff59.
Abstract:
Dans le contexte des matériaux composites Al/Al-Cu-Fe, la phase ω-Al7Cu2Fe et des composites Al/ω ont été élaborés puis les microstructures et les propriétés mécaniques de ces matériaux ont été étudiées. La phase ω a été élaborée sous forme monolithique et dense par compression isostatique à chaud et par frittage flash. Des essais de micro-indentation, de frottement intérieur et de compression couplés à des essais transitoires ont été réalisés entre 293 K et 1000 K. Une transition fragile-ductile entre 650 K et 820 K a été mise en évidence. Les courbes contrainte-déformation montrent une limite d'élasticité supérieure suivie uniquement par de l'adoucissement ou un stade à durcissement nul. La limite d'élasticité supérieure présente une forte dépendance en température suggérant des mécanismes de déformation thermiquement activés. L'évolution des volumes d'activation avec la contrainte appliquée présente deux régimes de températures avec une température de transition vers 900 K. Des observations de microscopie électronique en transmission révèlent une distribution hétérogène de dislocations. Ces résultats originaux sur la phase ω-Al7Cu2Fe montrent de fortes similitudes avec les propriétés bien connues de la phase quasicristalline Al-Cu-Fe associée et apportent de nouveaux éléments de compréhension de la plasticité de ces matériaux complexes. Deux composites Al/ω ont été élaborés par compression isostatique à chaud. L'un est obtenu à 673 K à partir de particules ω initiales tandis que l'autre est obtenu à 823 K à partir de particules Al-Cu-Fe initialement sous forme quasicristalline. La matrice, observée par microscopie électronique en transmission, présente une microstructure complexe avec différentes distributions de particules selon la température d'élaboration. A partir d'essais de compression couplés à des essais transitoires et à la diffraction de neutrons, le renforcement de la matrice Al est attribué au transfert de charge et au durcissement de la matrice par des microstructures différentesIn the general context of study of Al/Al-Cu-Fe composites, ω-Al7Cu2Fe phase and related Al/ω composites have been synthesised and their mechanical properties and microstructure investigated. Dense monolithic ω-Al7Cu2Fe phase synthesis was achieved for the first time using hot isostatic pressing and spark plasma sintering allowing for mechanical and microstructural investigations. Microindentation, compression and transient tests as well as mechanical spectroscopy have been performed in large temperature ranges. A brittle-to-ductile transition between 650 K and 820 K is evidenced. The stress-strain curves exhibit an upper yield stress followed by a softening or steady state stage only. The upper yield stress shows strong temperature dependence suggesting that deformation mechanisms are highly thermally activated. The evolution of activation volumes with the applied stress exhibits two deformation mechanisms with a transition temperature of 900 K. Transmission electron microscopy observations of deformed material reveal inhomogeneous dislocation distribution. The original results on the crystalline ω-Al7Cu2Fe phase exhibit a strong similarity with the well-known properties of the related icosahedral Al-Cu-Fe phase and shed a new light on the understanding of plasticity in these complex materials. Two Al/ω composites have been fabricated from powder metallurgy, one at 673 K from initial ω particles, the second at 823 K from initial icosahedral Al-Cu-Fe particles. Transmission electron microscopy observations reveal a complex matrix microstucture with different particles distribution according to the processing temperature. From compression and transient tests performed at various temperatures and in-situ compression test under neutron beam, the reinforcement of Al matrix is attributed to both load transfer and hardening of the matrix resulting from different microstructure
37
Ozyurda, Akin Halit. "Spray Rolling Of Rapidly Solidified Al-fe-v-si Alloy." Master's thesis, METU, 2006. http://etd.lib.metu.edu.tr/upload/12607312/index.pdf.
Abstract:
In this study an experimental spray-rolling set-up is designed in order to produce rapidly solidified Al-Fe-V-Si flat product. Al-Fe-V-Si alloys produced by rapid solidification powder metallurgy (RSP/M) methods are mostly used in high temperature applications in aerospace and automotive industries. The RSP/M technique used is spray deposition, which is desirable because of the high cooling rates achieved, as a result fine silicide dispersoids and intermetallics are observed in the microstructure which are known to contribute to the mechanical properties i.e. high strength at elevated temperatures, thermal stability, fracture toughness, corrosion resistance. Since spray deposition is a droplet consolidation process a considerable amount of porosity is expected in the final product. In this work, spray rolling process, which consists of spray deposition and subsequent hot twin-rolling stage, is designed and developed by interpreting the results obtained from SEM, XRD, tensile, three point bending and hardness tests of the specimens formed in several design stages. Two original intermetallic phases characterized in this study are V3Si and V2Mg3Al18 .
38
Strahl, Alexander. "Anelastische Relaxationen durch Punktdefekte und Versetzungen in Fe-Al-Legierungen." Berlin dissertation.de, 2006. http://www.digibib.tu-bs.de/?docid=00017200.
39
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.
40
Park, Woonsup. "Migration kinetics of antiphase boundaries in Fe-Al ordered alloys." Thesis, Massachusetts Institute of Technology, 1988. http://hdl.handle.net/1721.1/54326.
41
Martinez, Celis Mayerling. "Transformation de phases et comportement à l'oxydation d'alliages Fe-Al." Toulouse, INPT, 2007. http://ethesis.inp-toulouse.fr/archive/00000504/.
Abstract:
Les alliages basés sur les composés intermétalliques de type Fe-Al possèdent encore aujourd'hui une forte attractivité pour des applications industrielles, du fait de nombreuses propriétés intéressantes : tenue mécanique à relativement haute température, résistance à l'oxydation, faible coût d'élaboration. Cette thèse porte sur deux caractéristiques de ces familles d'alliages: i) les défauts microstructuraux, en particulier ceux liés aux phénomènes de mise en ordre et ii) l'oxydation à haute température. Nous avons travaillé sur quatre alliages différents : un alliage binaire Fe-40Al, deux alliages contenant des éléments d'addition (Fe-40Al-0,01B et Fe-40Al-2,7Ni-0,02B) et un alliage semi industriel (grade 3 contenant plusieurs éléments d'addition – Ni, Mn, Cr, Mo, B - et des particules de Y2O3). De plus, des couples de diffusion ont été réalisés entre chacun de ces alliages et du fer. Ces couples nous ont permis d'étudier les phénomènes de diffusion et de disposer d'échantillons avec une teneur variable en aluminium. Au cours de la caractérisation microstructurale des alliages nous avons analysé les défauts plans complexes liés à la présence de bore. L'étude des couples de diffusion a été réalisée par analyse chimique (EDS) et par l'observation en microscopie électronique en transmission des différents domaines créés par la mise en ordre au cours des traitements thermiques (domaines d'antiphase APD). Ces résultats permettent de révéler l'influence de la composition des alliages sur la diffusion et les températures de transformation. Nous montrons en particulier que l'addition de nickel ralentit la diffusion et semble étendre le domaine d'existence de la phase B2. L'étude de la cinétique d'oxydation a été menée par analyse thermogravimétrique à 800 et 1000°C sur les différents alliages fer-aluminium ainsi que sur des sections des couples de diffusion. Les résultats des prises de masse complétées par l'analyse en diffraction de rayons X et par des observations en MEB permettent de préciser la nature des oxydes formés en fonction de la composition des alliages. Nous avons pu ainsi préciser la teneur minimale d'aluminium nécessaire pour bloquer l'oxydation du fer (19 %at. ) et le rôle du nickel sur la cinétique d'oxydationThe numerous good properties of alloys based on Fe-Al compounds still make them good candidates for industrial applications (good strength, good oxidation resistance, low production cost). This thesis word focuses on two characteristics of such alloys: i) microstructural defects, with emphasis on defects linked to ordering and ii) high temperature oxidation. We have studied four different alloys : a binary Fe-40Al, two alloys with additional elements (Fe-40Al- 0. 01B and Fe-40Al-2. 7Ni-0. 02B) and a semi-industrial alloy (grade 3 including alloying elements – Ni, Mn, Cr, Mo, B – and Y2O3 particles). Diffusion couples were also elaborated between these alloys and iron, which allowed to study diffusion and produce specimens with a varying aluminium content. The microstructural characterisation helped us to determine the precise nature of the complex planar faults observed in boron containing alloys. The study of diffusion couples was performed by chemical analysis and by characterising by transmission electron microscopy the antiphase domains due to the ordering that occurred during thermal treatments. These results reveal the incidence of alloy composition on diffusion and transformation temperatures. We showed that nickel addition slows down diffusion kinetics and seems to expand the stability domain of B2 phase. Oxidation kinetics study has been achieved by thermo gravimetric analysis performed at 800 and 1000°C on the different Fe- l alloys and on specimens extracted from the diffusion couples. Mass gain results complemented by X ray diffraction and SEM observations allow determine the oxides formed depending on the specimen composition. We could show thus determine the minimum aluminium content needed to impede iron oxidation (19 at. %) and we highlighted the effect of nickel on oxidation kinetics
42
Устинова, Е. В., and Е. В. Суховая. "Структурообразование квазикристаллических сплавов Al-Cu-Fe, легированных Si и B." Thesis, Сумский государственный университет, 2014. http://essuir.sumdu.edu.ua/handle/123456789/39445.
Abstract:
Стабильная икосаэдрическая ψ-фаза (Al[6]Cu[2]Fe), обладающая уникальными свойствами, была обнаружена в системе Al–Cu–Fe. Несмотря на широкое внимание к новому классу квазикристаллов, фазовая диаграмма системы Al–Cu–Fe при легировании Si и B в области существования икосаэдрической фазы не достаточно определена. Влияние легирующих элементов на структуру сплавов Al–Cu–Fe остается спорным. Поэтому целью работы является изучение влияния Si и B на фазовый состав сплавов Al–Cu–Fe.
43
Zuazo, Rodriguez Ian Alberto. "Evolution microstructurale dans les alliages légers Fe-Al-Mn-C." Grenoble INPG, 2009. http://www.theses.fr/2009INPG0054.
Abstract:
Mon sujet de thèse consistait à clarifier l'évolution microstructurale des aciers légers multiphasés. La première partie de ces travaux décrit de façon détaillée les séquences de transformations de phases et présente les domaines où l'austénite est stable. Par la suite, la cinétique de croissance isotherme de l'austénite a été mesurée. La cinétique a été modélisée avec des modèles binaires et ternaires. Le logiciel DICTRA a seulement permis de faire une analyse qualitative à cause des limitations de la base de données thermodynamique. Une attaque profonde ainsi que la technique EBSD a permis de corréler la morphologie de la phase K. La modélisation de la phase K a nécessité une meilleure connaissance de l'équilibre des phases pour parvenir à des résultats convaincantsIn this work emphasis is put on the clarification of the complex microstructural evolution in multiphase lightweight steels. In the first part of this investigation detailed sequences of phase transformations are proposed and the domains where austenite is stable are given. Then isothermal growth kinetics of austenite was measured. Kinetics was modeled with known binary and ternary models. The DICTRA software provided only a qualitative description due to the shortcomings of the thermodynamic database. A deep-etching procedure together with the EBSD technique provided a correlation between morphology of the K-phase and orientation relationships with ferrite. Isothermal growth kinetics was measured in two morphologies of the K-phase. Modeling of the K-phase required a better knowledge of phase equilibria to yield proper results
44
Martinez, Celis Mayerling Viguier Bernard. "Transformation de phases et comportement à l'oxydation d'alliages Fe-Al." Toulouse : INP Toulouse, 2008. http://ethesis.inp-toulouse.fr/archive/00000504.
45
Quehen, Hélène. "Étude métallurgique d'alliages intermétalliques Fe₃Al-Cu élaborés par fonderie." Electronic Thesis or Diss., Université de Lorraine, 2023. https://docnum.univ-lorraine.fr/ulprive/DDOC_T_2023_0359_QUEHEN.pdf.
Abstract:
Le développement des alliages métalliques complexes, dont les HEA sont un parangon, requiert de connaître à minima la nature des phases sur l'ensemble des diagrammes de phase multiconstitués, tout du moins au-delà de la proximité des systèmes binaires sur lesquels ils s'adossent. Le système Fe-Al-Cu est un des systèmes ternaires importants, même si son étude s'est surtout concentrée sur le coin riche en Al pour sa propension à former des phases quasi-cristallines. Dans ce contexte, et en vue de compléter les connaissances dans les régions intermédiaires entre Fe₃Al et Cu₃Al plus rarement explorées, nous avons réalisé une étude de caractérisation d'un ensemble d'alliages élaborés par fonderie, et soumis à des traitements thermiques généralement utilisés pour optimiser les propriétés des intermétalliques Fe₃Al. Dans un premier temps, nous avons complété les sections ternaires à 600°C et 700°C et mis en évidence des différences quantitatives avec les diagrammes de la littérature sur les frontières du domaine triphasé FeAl/Cu₃Al/Cu₉Al₄. Dans un second temps, nous nous sommes intéressés à des alliages se répartissant sur les axes Fe-28Al-XCu (X = 15, 20 et 25%at.) et Fe-XAl-15Cu (X = 20 et 30%at.). Nous en avons caractérisé les microstructures à l'état brut de solidification et après différents traitements thermiques, par microscopies électroniques (à balayage et à transmission) et diffraction des rayons X (de laboratoire et hautes énergies). Nous avons mis en évidence la présence quasi systématique de deux phases intermétalliques : Fe₃Al et Cu₃Al 18R, issue de la transformation martensitique des régions riches en Cu. Leur proportion est inversée suivant la position dans la microstructure générée par l'étape de solidification : alors que Cu₃Al peuple plaquette répartis au cœur des dendrites constituées majoritairement de Fe₃Al, on observe dans les zones interdendritiques riche en cuivre des précipités cuboïdaux de Fe₃Al dispersés dans une matrice Cu₃Al. Il apparaît que les traitements thermiques habituellement appliqués aux alliages Fe₃Al ne changent pas fondamentalement cette microstructure, si ce n'est qu'ils tendent à globulariser les différents domaines riches en CuThe development of complex metallic alloys, of which HEAs are a paragon, requires at least the knowledge of the nature of the phases on the whole multicomponent phase diagrams, at least beyond the proximity of the binary systems on which they are based. The Fe-Al-Cu system is one of the most important ternary systems, even if its study has mainly focused on the Al rich corner because of its propensity to form quasi-crystalline phases. In this context, and in order to complete the knowledge in the intermediate regions between Fe₃Al and Cu₃Al, which are less explored, we have carried out a characterization study of a series of alloys elaborated by casting and subjected to heat treatments generally used to optimize the properties of Fe₃Al intermetallics. In a first step, we completed the ternary sections at 600°C and 700°C and highlighted the quantitative differences with the literature diagrams on the boundaries of the FeAl/Cu₃Al/Cu₉Al₄ three-phase domain. In a second step, we focused on alloys distributed along the Fe-28Al-XCu (X = 15, 20 and 25 at.%) and Fe-XAl-15Cu (X = 20 and 30 at.%) axes. We have characterized the microstructures in the as-solidified state and after different thermal treatments by electron microscopy (scanning and transmission) and X-ray diffraction (laboratory and high energy). We have highlighted the quasi-systematic presence of two intermetallic phases: Fe₃Al and Cu₃Al 18R, resulting from the martensitic transformation of Cu-rich regions. Their proportion is reversed according to the position in the microstructure generated by the solidification step: while Cu₃Al populates cuboidal domains distributed in the dendritic core composed mainly of Fe₃Al, one observes in the copper-rich interdendritic zones Fe₃Al platelets dispersed in a Cu₃Al matrix. It appears that the heat treatments usually applied to Fe₃Al alloys do not fundamentally alter this microstructure, except that they tend to globularize the different Cu-rich domains
46
Bekker, Viacheslav. "Entwicklung neuartiger thermisch stabiler weichmagnetischer Fe-Co-Al-N- und Fe-Co-Ta-N-Dünnschichtmaterialien für Hochfrequenzanwendungen." Karlsruhe : FZKA, 2005. http://bibliothek.fzk.de/zb/berichte/FZKA7169.pdf.
47
Santos, Claudio Teodoro dos. "Efeito das adições de boro na magnetostricção de ligas policristalinas dos sistemas Fe-Al e Fe-Ga." Universidade de São Paulo, 2013. http://www.teses.usp.br/teses/disponiveis/97/97135/tde-08102013-083643/.
Abstract:
Os materiais magnetostrictivos apresentam deformação elástica quando são submetidos a um campo magnético ou mudança das propriedades magnéticas quando são submetidos a uma tensão mecânica, e por isso são de grande interesse para aplicações em atuadores, sensores e aproveitadores de energia. Entretanto, os melhores materiais magnetostrictivos disponíveis são caros e frágeis. Nos últimos anos foi descoberta uma nova classe de materiais magnetostrictivos que superam este problema, a classe das ligas Fe-Ga e Fe-Al, que possuem a rara combinação de moderada magnetostricção, boas propriedades mecânicas e baixo custo associado. Atualmente, as pesquisas têm buscado meios de melhorar a magnetostricção destas ligas, tanto por adições ternárias de outros átomos, como pela utilização de diferentes métodos de fabricação, tratamentos térmicos ou processamentos mecânicos. No presente trabalho foi avaliado o efeito das adições de B e do processo de solidificação rápida na magnetostricção e microestrutura das ligas Fe-Al e Fe-Ga. Para isso, ligas policristalinas de composição nominal (Fe80Al20)1-0,01yBy, (Fe80Ga20)1-0,01yBy e (Fe72Ga28)1-0,01yBy, com y = 0; 0,5; 1; 1,5 e 2% at., foram produzidas por fusão a arco e pela técnica de solidificação rápida \"splat cooling\". A caracterização microestrutural das amostras foi realizada no MEV/EDS e DRX. A magnetostricção foi medida com campo magnético de 0 a ±2 T em 4,2, 77 e 300 K, por dilatometria de capacitância. As adições de B ocasionaram a precipitação de Fe2B nos contornos de grão da fase A2 e/ou D03 das ligas Fe-Al e Fe-Ga, resultando na redução do tamanho de grão e formação de cristais dendríticos. As ligas Fe80Al20 apresentaram um valor máximo de magnetostricção de 74 ppm com a adição de 2% at. de B. Já as ligas Fe80Ga20 e Fe72Ga28 apresentaram um máximo com a adição de 1% at. de B, sendo de 81 ppm e 143 ppm, respectivamente. Conclui-se que estas adições de B tiveram um efeito benéfico na magnetostricção das ligas Fe-Al e Fe-Ga como-solidificadas, uma vez que chegaram a ocasionar um aumento de até 100% desta propriedade em relação à liga sem B. Por outro lado, a solidificação rápida não teve efeito sobre a magnetostricção das ligas Fe-Al-B.Magnetostrictive materials exhibit elastic deformation when subjected to a magnetic field or changing in magnetic properties when subjected to mechanical stress, so they are of great interest for applications in actuators, sensors and energy harvesters. However, the best available magnetostrictive materials are expensive and fragile. In the last years has been discovered a new class of magnetostrictive material which overcome this problem, the class of the Fe-Ga and Fe-Al alloys, which have the unusual combination of moderate magnetostriction, good mechanical properties and low associated cost. Currently, research has searched ways to improve the magnetostriction of these alloys, both for ternary additions of other atoms or by using different methods of preparation, heat treatment or mechanical processing. In the present study, we evaluated the effect of B additions and rapid solidification process on the microstructure and magnetostriction of Fe- Al and Fe-Ga alloys. For this purpose, polycrystalline alloys of nominal composition (Fe80Al20)1-0.01yBy, (Fe80Ga20)1-0.01yBy and (Fe72Ga28)1-0.01yBy, with y = 0, 0.5, 1, 1.5 e 2 at.% were produced by arc melting and splat cooling rapid solidification technique. Microstructural characterization of the samples was performed by SEM/EDS and XRD. The magnetostriction was measured under magnetic field of 0 to ±2 T, at 4.2, 77 and 300 K, by capacitance dilatometry. The B additions caused precipitation of Fe2B at the grain boundaries of A2 and/or D03 phase of Fe-Al and Fe-Ga alloys, resulting in a reduction of the grain size and formation of dendritic crystals. The Fe80Al20 alloys showed a maximum magnetostriction of 74 ppm with the addition of 2 at.% B. And, the Fe80Ga20 and Fe72Ga28 alloys showed a peak with the addition of 1 at.% B, of 81 ppm and 143 ppm, respectively. We concluded that these B additions had a beneficial effect on the magnetostriction of Fe- Al and Fe-Ga as-cast alloys, since they caused an increase up to 100% of this property in relation to the alloy without B. On the other hand, the rapid solidification had no the same effect on the magnetostriction of Fe-Al-B alloys.
48
Silva, Antonio Augusto Araújo Pinto da. "Thermodynamic modeling and critical experiments on the Al-Fe-Nb system." Thesis, Université de Lorraine, 2015. http://www.theses.fr/2015LORR0148.
Abstract:
Les diagrammes d’équilibre sont le point de départ et la ligne directrice qui permet de prévoir et contrôler les phases pouvant se former au cours de différents processus industriels. Bien que l’étude expérimentale soit nécessaire pour les systèmes binaires et ternaires, elle est difficilement envisageable pour déterminer les diagrammes de phases des systèmes d’ordre supérieur sur de larges gammes de composition et de température. Afin de contourner ce problème, la méthode dite CALPHAD (CALculation of PHAse Diagram) a été développée. Son principe consiste à optimiser les paramètres des modèles thermodynamiques utilisés pour décrire l´énergie libre de Gibbs de chaque phase à partir d’informations expérimentales ou estimées (ab-initio). Le modèle appelé « Compound Energy Formalism » (CEF) est largement utilisé pour décrire les phases qui présentent plusieurs sous-réseaux. Ce modèle et ceux qui en dérivent permettent la modélisation d'une grande variété de composés. Les activités menées au cours de ce travail ont permis de développer une nouvelle approche du CEF (NACEF) basée sur une étude mathématique de ses paramètres thermodynamiques. Elle a conduit à une nouvelle formulation de la fonction d'énergie libre de Gibbs faisant intervenir de nouveaux paramètres indépendants. Cette nouvelle approche a été utilisée dans le cadre de ce travail afin de modéliser les phases intermétalliques binaires constituée de deux sous-réseaux présentant des défauts uniquement de type anti-sites (A,B)a(A,B)b. Le système Al-Fe-Nb sur lequel porte notre étude a été choisi en raison de son importance dans la fabrication de nombreuses familles d'alliages tels que les aciers, les alliages légers et plus récemment dans le développement de nouveaux matériaux réfractaires à base Nb pour des applications à hautes températures. Dans ce travail, de nouvelles modélisations des bordures binaires Al-Nb et Fe-Nb et pour la première fois du ternaire Al-Fe-Nb sont proposées en utilisant la NACEF et en s’appuyant sur les informations issues de la littérature ou obtenues dans cette étudeThe equilibrium diagrams are the starting point and the guideline to predict and control the microstructure that will form during processing materials. Despite experiments being necessary in binaries and ternaries systems, it is difficult to experimentally determine phase diagrams of higher orders systems over wide ranges of compositions and temperature. The CALPHAD (CALculation of PHAse Diagrams) method was developed in order to solve this problem. The essence is to optimize the parameters of thermodynamic models that describe the Gibbs free energies of each phase aiming to reproduce the experimental and estimated (ab-initio) data. The compound energy formalism (CEF) is widely used in order to describe phases which present several sublattices. It allows the modeling of a large variety of phases and numerous methods have been developed to treat different situations. The activities in this work developed a new approach of the CEF (NACEF) based on a mathematic analysis of the parameters which leads to a new formulation of the Gibbs free energy function evolving new independent parameters in which new independent parameters are obtained to express the Gibbs free energy. This approach was used in this work to describe the intermetallic phases with two-sublattice in which the only defect type is anti-sites (A,B)a(A,B)b. The Al-Fe-Nb system was chosen due to its importance for the manufacturing process of several families of alloys currently used, e.g. steels, light alloys, and also for the development of new materials for high temperatures application. The binaries Al-Nb and Fe-Nb were reassessed and the Al-Fe-Nb system was assessed for the first time using literature information and new experimental data
Os diagramas de equilíbrio são o ponto de partida e a diretriz para prever e controlar a microestrutura ao final do processamento de um material. Apesar de experimentos serem necessários em sistemas binários e ternários, é muito difícil determinar experimentalmente diagramas de fase de sistemas de ordens superiores numa vasta amplitude de composições e temperatura. A fim de solucionar este problema, o método CALPHAD (CALculation of PHAse Diagrams) foi desenvolvido. A essência consiste em aperfeiçoar os parâmetros de modelos termodinâmicos que descrevem as energias livres de Gibbs de cada fase de modo a reproduzir as informações experimentais ou estimadas (ab-initio). O compound energy formalism (CEF) é amplamente utilizado para descrever fases que apresentam várias sub-redes. Ele permite a modelagem de uma grande variedade de fases e vários métodos têm sido desenvolvidos para o tratamento de diferentes situações. As atividades deste trabalho ajudaram a desenvolver uma nova abordagem para o CEF (NACEF) com base em um estudo matemático dos seus parâmetros termodinâmicos que levou a uma nova formulação para função da energia livre de Gibbs envolvendo novos parâmetros independentes. Esta nova abordagem tem sido utilizado como parte do presente trabalho para modelar fases intermetálicas binárias constituídas de sub-redes cujo único defeito é do tipo anti-sítio (A,B)a(A,B)b. O sistema Al-Fe-Nb foi escolhido devido a sua importância para o processo de fabricação de diversas famílias de ligas usadas atualmente, e.g. aços, ligas leves e, além disto, é um sistema importante para o desenvolvimento de materiais para aplicações em altas temperaturas. Neste trabalho os binários Al-Nb e Fe-Nb foram reavaliados e o sistema Al-Fe-Nb foi modelado pela primeira vez utilizando as informações da literatura e novos dados experimentais
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Zienert, Tilo [Verfasser], Andreas [Akademischer Betreuer] Leineweber, Andreas [Gutachter] Leineweber, Hans [Gutachter] Flandorfer, and Olga [Gutachter] Fabrichnaya. "Predicting heat capacity and experimental investigations in the Al-Fe and Al-Fe-Si systems as part of the CALPHAD-type assessment of the Al-Fe-Mg-Si system / Tilo Zienert ; Gutachter: Andreas Leineweber, Hans Flandorfer, Olga Fabrichnaya ; Betreuer: Andreas Leineweber." Freiberg : Technische Universität Bergakademie Freiberg, 2018. http://d-nb.info/1221070843/34.
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Zapico, Alvarez David. "Mechanisms and kinetics of the galvannealing reactions on Ti IF steels." Thesis, Châtenay-Malabry, Ecole centrale de Paris, 2014. http://www.theses.fr/2014ECAP0019.
Abstract:
Les revêtements galvanisés alliés sont produits par immersion à chaud d’une bande d'acier dans un bain de zinc fondu à environ 460 °C, saturé en fer et contenant de faibles quantités d'aluminium (de 0,1 à 0,135% poids), suivie d’un traitement thermique (jusqu'à des températures voisines de 500-530 °C pendant environ 10 s) afin de déclencher les réactions d'alliation entre le fer et le zinc. La microstructure finale de ce type de revêtement est composée d'une succession de couches stratifiées de phases Fe-Zn et ses propriétés d'usage sont directement liées à la distribution de ces phases dans le revêtement. Les paramètres process à appliquer sur ligne industrielle doivent donc être optimisés pour obtenir la microstructure de revêtement souhaitée avec des coûts minimaux. Le développement d'un tel revêtement passe par différentes réactions complexes : la formation de la couche d'inhibition, la rupture de cette couche, la consommation du zinc liquide et l'enrichissement en fer du revêtement solide. Les cinétiques de ces réactions doivent être étudiées et modélisées séparément afin de contrôler avec précision l'évolution du revêtement au cours du cycle thermique. Dans ce travail, les deux premières réactions ont été étudiées dans le cas des aciers IF Ti. La cinétique de formation de la couche d'inhibition est extrêmement rapide et n’a par conséquent pas été étudiée. L'attention a été portée sur la nature de cette couche et sur les mécanismes responsables de sa formation. Il a été démontré que la couche d'inhibition formée dans des bains classiques pour la production de ces revêtements est composée d'une première couche très mince de Fe2Al5Znx (20-30 nm) sur la surface de l’acier et d’une seconde couche plus épaisse de δ (FeZn7) (environ 200 nm) au-dessus. Lorsque l'acier est immergé dans le bain de zinc, la dissolution du premier dans le second conduit à une sursaturation en fer à l'interface solide / liquide. Une très fine couche de Fe2Al5Znx métastable germe alors sur la surface de l'acier favorisée par des relations préférentielles d’épitaxie avec la ferrite. Par la suite, une couche de δ germe sur la couche de Fe2Al5Znx ce qui permet à la microstructure finale de devenir thermodynamiquement stable. L'effet de la teneur en aluminium du bain sur la nature de la couche d'inhibition a également été étudié. Quand la teneur en aluminium du bain diminue, la couche de Fe2Al5Znx devient discontinue car cette phase devient plus métastable et sa germination sur la surface de l'acier moins probable. Cette étape d’inhibition n'est que transitoire et un traitement thermique prolongé conduira à la rupture de la couche d'inhibition et au développement des réactions Fe-Zn. Le mécanisme de rupture, contrôlé par la diffusion du zinc dans les joints de grains de l'acier, peut être expliqué à l'aide du diagramme de phase ternaire Al-Fe-Zn et résumé en deux étapes : la disparition de la couche de Fe2Al5Znx à l'interface couche d’inhibition / acier résultant de l’enrichissement de cette interface en zinc, et la germination de la phase Г (Fe3Zn10) aux joints de grains de l'acier lorsque la concentration en zinc y devient suffisante. C’est cette germination qui va provoquer localement la rupture de la couche d’inhibition. La cinétique de cette réaction dépend fortement de la composition chimique de l'acier IF Ti et de la teneur en aluminium du bain. D'une part, il apparaît que l'effet de la composition chimique de l'acier sur la cinétique de rupture d'inhibition est contrôlé par la compétition entre deux phénomènes opposés : la vitesse de diffusion du zinc dans les joints de grains de l'acier et la capacité de l'acier à y accumuler les atomes de zinc. D'autre part, la diminution de la teneur en aluminium du bain favorise la discontinuité de la couche de Fe2Al5Znx, ce qui accélère la rupture de la couche d'inhibition car le zinc est supposé diffuser plus rapidement dans δ que dans Fe2Al5ZnxHot-Dip GalvAnnealed (HDGA) coatings are produced by the immersion of the steel strip into an iron-saturated liquid zinc bath at around 460 °C containing small amounts of aluminium (from 0.1 to 0.135 wt.%, normally) and its subsequent heating (up to temperatures around 500-530 °C for about 10 s, typically) in order to trigger the alloying reactions between iron and zinc. The final microstructure of this kind of coatings is composed of a sequence of stratified Fe-Zn phase layers and its in-use properties are directly related to the phase distribution within the coating. The process parameters to be performed in industrial lines must therefore be optimized in order to obtain a successful coating microstructure with the minimum costs. The development of such a coating passes through different and complex reactions: the inhibition layer formation, the inhibition layer breakdown, the liquid zinc consumption and the iron enrichment of the solid coating. The kinetics accounting for these reactions must be studied and modelled separately in order to accurately control the evolution of the coating along the heat treatment performed in the industrial line. In the present work, the two first reactions were investigated in the case of Ti IF steel grades. The kinetics of the inhibition layer formation is extremely fast and has therefore not been investigated in detail. Concerning this reaction, the focus was given to the nature of this inhibition layer and to the mechanisms accounting for its formation. It has been found that the inhibition layer formed in typical baths for galvannealed coatings production is composed of a very thin layer of the Fe2Al5Znx phase (20-30 nm) on the steel surface and a thicker layer of the δ (FeZn7) phase (around 200 nm) on its top. As the steel strip enters the zinc bath, iron dissolution from the former into the latter leads to an iron supersaturation at the solid / liquid interface. As a result, a very thin layer of metastable Fe2Al5Znx nucleates on the steel surface favoured by preferential epitaxial relationships with ferrite. Subsequently, δ nucleates on the Fe2Al5Znx layer allowing the final microstructure of the inhibition layer to become thermodynamically stable. The effect of the bath aluminium content on the nature of this inhibiting structure has also been studied. As the bath aluminium content is lowered, the Fe2Al5Znx layer becomes discontinuous: the lower the bath aluminium content is, the higher the metastability of Fe2Al5Znx is and the less probable its nucleation on the steel surface is. The inhibition state is only transient and continued heat treatment will lead to the inhibition layer breakdown and the development of the further Fe-Zn alloying reactions. The breakdown mechanism, controlled by the diffusion of zinc towards the steel grain boundaries, can be explained using the Al-Fe-Zn ternary phase diagram and summarized in two steps: the disappearance of the Fe2Al5Znx layer at the inhibition layer / steel interface as a result of the enrichment of this interface in zinc, and the local nucleation of the Г (Fe3Zn10) phase at the steel grain boundaries, breaking the inhibition layer off, when the zinc concentration at these locations becomes high enough. The kinetics accounting for this reaction strongly depends on the Ti IF steel chemical composition and the bath aluminium content. On the one hand, it has been found that the effect of the steel chemical composition on the inhibition layer breakdown kinetics would be ruled by the competition between two opposite phenomena: the rate of zinc diffusion at the steel grain boundaries and the ability of the steel to accumulate the zinc atoms at these locations On the other hand, decreasing the bath aluminium content favours the discontinuity of Fe2Al5Znx, which accelerates the inhibition layer breakdown as zinc is expected to diffuse faster through δ than through Fe2Al5Znx