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Lytvynenko, Ia M. "Magnetic properties of thin film Ni-Fe-Co alloy." Thesis, Sumy State University, 2014. http://essuir.sumdu.edu.ua/handle/123456789/39709.
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In recent years, considerable attention has been devoted to the investigation of the physical properties of ultrathin magnetic lms of 3d transition metals and thin lm structures based on its because of their application in nanoelectronics. Frequent use of ferromagnetic alloys as elements of structures that exhibit AMR, GMR or TMR making them of the relevant object of research.
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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.
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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.
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Clark, Justin Lewis. "Dynamic and Quasi-Static Mechanical Properties of Fe-Ni Alloy Honeycomb." Diss., Georgia Institute of Technology, 2004. http://hdl.handle.net/1853/5223.
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Several metal honeycombs, termed Linear Cellular Alloys (LCAs), were fabricated via a paste extrusion process and thermal treatment. Two Fe-Ni based alloy compositions were evaluated. Maraging steel and Super Invar were chosen for their compatibility with the process and the wide range of properties they afforded. Cell wall material was characterized and compared to wrought alloy specifications. The bulk alloy was found to compare well with the more conventionally produced wrought product when porosity was taken into account. The presence of extrusion defects and raw material impurities were shown to degrade properties with respect to wrought alloys. The performance of LCAs was investigated for several alloys and cell morphologies. The results showed that out-of-plane properties exceeded model predictions and in-plane properties fell short due to missing cell walls and similar defects. Strength was shown to outperform several existing cellular metals by as much as an order of magnitude in some instances. Energy absorption of these materials was shown to exceed 150 J/cc at strains of 50% for high strength alloys. Finally, the suitability of LCAs as an energetic capsule was investigated. The investigation found that the LCAs added significant static strength and as much as three to five times improvement in the dynamic strength of the system. More importantly, it was shown that the pressures achieved with the LCA capsule were significantly higher than the energetic material could achieve alone. High pressures, approaching 3 GPa, coupled with the fragmentation of the capsule during impact increased the likelihood of initiation and propagation of the energetic reaction. This multi-functional aspect of the LCA makes it a suitable capsule material.
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EverhartC, Charles. "The Electrodeposition of Fe-Ni-Cr Alloys from Aqueous Electrolytes." Cleveland, Ohio : Case Western Reserve University, 2009. http://rave.ohiolink.edu/etdc/view?acc_num=case1252092401.
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Thesis(M.S.)--Case Western Reserve University, 2009Title from PDF (viewed on 2010-01-28) Department of Chemical Engineering Includes abstract Includes bibliographical references and appendices Available online via the OhioLINK ETD Center
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Jafarian, Hamidreza. "Martensitic Transformation from Ultrafine Grained Meta-stable Austenite in Fe-Ni-C Alloy." 京都大学 (Kyoto University), 2012. http://hdl.handle.net/2433/152514.
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Liu, Yijun. "Amorphisation and characterisation of multicomponent Fe-Co-Ni-Zr-B alloys during mechanical alloying." Thesis, University of Birmingham, 2000. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.368795.
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Lemanski, Jennifer. "CRYOGENIC SHAPE MEMORY ALLOY ACTUATORS FOR SPACEPORT TECHNOLOGIES: MATERIALS CHARACTERIZATION AND PROTOTYPE TESTING." Master's thesis, University of Central Florida, 2005. http://digital.library.ucf.edu/cdm/ref/collection/ETD/id/2779.
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Shape memory alloys (SMAs) possess the unique ability to change their shape by undergoing a solid-state phase transformation at a particular temperature. The shape change is associated with a large strain recovery as the material returns to its "remembered" shape. Their ability to act as both sensor and actuator has made them an attractive subject of study for numerous applications. SMAs have many characteristics which are advantageous in space-related applications, including generation of large forces associated with the strain recovery, smooth and controlled movements, large movement to weight ratio, high reliability, and spark-free operation. The objective of this work is the further development and testing of a cryogenic thermal conduction switch as part of NASA funded projects. The switch was developed to provide a variable conductive pathway between liquid methane and liquid oxygen dewars in order to passively regulate the methane temperature. Development of the switch concept has been continued in this work by utilizing Ni-Ti-Fe as the active SMA element. Ni-Ti-Fe exhibits the shape memory effect at cryogenic temperatures, which makes it well suited for low temperature applications. This alloy is also distinguished by an intermediate phase change known as the rhombohedral or R-phase, which is characterized by a small hysteresis (typically 1-2 deg C) and offers the advantage of precise control over a set temperature range. For the Ni-Ti-Fe alloy used, its thermomechanical processing, subsequent characterization using dilatometry and differential scanning calorimetry and implementation in the conduction switch configuration are addressed. This work was funded by grants from NASA KSC (NAG10-323) and NASA GRC (NAG3-2751).M.S.M.S.E.
Department of Mechanical, Materials and Aerospace Engineering;
Engineering and Computer Science
Materials Science and Engineering
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Malet, Loïc. "The formation of plate martensite in a Fe-High Ni alloy: Crystallography and Variant Selection." Doctoral thesis, Universite Libre de Bruxelles, 2015. http://hdl.handle.net/2013/ULB-DIPOT:oai:dipot.ulb.ac.be:2013/227689.
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Mainly two different morphologies of martensite can be obtained in steels depending on the amount of alloying elements. The first morphology, referred to as lath martensite, forms in low alloy, low carbon steels. It is, by far, the most extensively studied form of martensite due to its industrial applications. The second morphology of martensite, referred to as plate martensite, forms in highly alloyed and in high carbon steels and in particular in Fe-High Ni alloys. In this case, the transformation product is disc shaped and internally twinned. This morphology is the only form of martensite that has the potential to exhibit shape memory properties. It is therefore of great interest to understand the mechanisms of its formation. This is investigated in the present dissertation through the study of the martensitic transformation occurring in a Fe-30.5%Ni-0.155%C alloy. More precisely, the influence of stress and grain size on the crystallography of plate martensite is discussed in the general framework of the phenomenological theory of martensite crystallography. This theory allows associating a unique shape deformation to each orientational variant. In this way, the experimental observations carried out at different length scales by means of optical microscopy, EBSD and TEM can be used to infer the transformation path followed under different conditions. Firstly, the burst configurations of variants observed in coarse-grained austenite under stress free conditions are rationalized by considering the mechanical couplings between the variants. It is shown that self-accommodating and autocatalytic couplings are responsible for the formation of hierarchical configurations of variants. More precisely, the transformation is shown to occur through the alternate formation of perpendicular plate groups of variants. Self-accommodation is the dominant coupling between variants of the same plate group while autocatalytic couplings are responsible for the transfer of the transformation from one generation to the next. It is suggested that the plastic accommodation of the shape deformation plays a dominant role in propagating the transformation to a lower length scales. Secondly, the influence of a uniaxial stress state on the transformation is studied. It is seen experimentally that only the most favoured variants are systematically formed in coarse Cube grains while coarse non-Cube grains generally transform into plate groups of variants that are only moderately favoured by the stress. These observations are well explained by considering the interaction energy between the applied stress and the shape deformation associated with the transformation. Thirdly, the influence of the austenitic grain size on the transformation is also studied. A decrease in grain size is seen to decrease the martensite start temperature. For a grain size below about 10µm, the thermal transformation in liquid nitrogen is indeed suppressed in the present alloy. This observation is related to the increasing yield strength of austenite as the grain size is reduced. A noticeable change in the morphology of martensite also accompanies the decrease in grain size. Indeed, martensite forming in coarse-grained austenite is mostly lens shaped and partially twinned while it appears plate shaped and fully twinned in smaller grains. Furthermore, martensite forming in fine-grained austenite develops self-accommodating configurations suggesting that most of the transformation deformations are elastically accommodated in this case. This is believed to be related to the observance of a shape memory effect in the present alloy in its fine-grained condition.Doctorat en Sciences de l'ingénieur et technologie
info:eu-repo/semantics/nonPublished
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Inturi, Rama Brahmam. "Structure, Composition and Pitting Behavior of Sputtered AI Base, Fe Base, and NI Base Alloy Films." The Ohio State University, 1993. http://rave.ohiolink.edu/etdc/view?acc_num=osu1392213869.
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Inturi, Rama Brahmam. "Structure, composition and pitting behavior of sputtered Al base, Fe base, and Ni base alloy films /." The Ohio State University, 1993. http://rave.ohiolink.edu/etdc/view?acc_num=osu1487841975356911.
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Pharkya, Pallavi. "Properties and Durability of the Passive Films on a Ni-Cr-Mo Alloy and an Fe-based Bulk Metallic Glass." Case Western Reserve University School of Graduate Studies / OhioLINK, 2009. http://rave.ohiolink.edu/etdc/view?acc_num=case1232857493.
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CARNEIRO, VIVIANE DELVAUX. "RECIPITATION PROCESSES CONTROLLED BY LATTICE AND GRAIN BOUNDARY DIFFUSION IN ALLOY 33 (FE-NI-CR-MO-N)." PONTIFÍCIA UNIVERSIDADE CATÓLICA DO RIO DE JANEIRO, 2004. http://www.maxwell.vrac.puc-rio.br/Busca_etds.php?strSecao=resultado&nrSeq=5927@1.
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COORDENAÇÃO DE APERFEIÇOAMENTO DO PESSOAL DE ENSINO SUPERIOREste trabalho é uma investigação da microestrutura e cinética dos fenômenos de precipitação que ocorrem na Liga 33 (Fe-Ni-Cr-Mo-Cu-N), sistema metálico desenvolvido pela Krupp VDM com o intuito de suportar altas temperaturas e ambiente corrosivo. A Liga 33 incorre precipitação contínua e descontínua simultaneamente, como resultado do tratamento de envelhecimento realizado numa faixa de temperatura correspondente àquela que o material atinge quando submetido a um processo de soldagem. A caracterização microestrutural foi realizada por microscopia ótica, microscopia eletrônica de varredura, e microscopia eletrônica de transmissão, incluindo microanálise, devido à ordem de grandeza nanométrica das fases precipitadas. A precipitação descontínua ocasiona uma estrutura lamelar no contorno dos grãos, resultado do crescimento cooperativo entre as lamelas, envolvendo átomos substitucionais (Cr, por exemplo) e intersticiais (N). A precipitação contínua ocorre no interior dos grãos gerando precipitados com diferentes morfologias. A microanálise revela que os produtos gerados em ambas as reações crescem competindo pelo Cr. Uma análise cinética- morfológica aponta para a natureza não estacionária da reação descontínua, que sofre gradativa diminuição de sua taxa de transformação, até ser totalmente paralisada.
This work is an investigation of the microstructure and kinetics of the phenomena occurring inside Alloy 33 (Fe-Ni- Cr-Mo-Cu-N), a metallic system developed by Krupp VDM to endure high temperatures and corrosive environment. Alloy 33 incurs continuous and discontinuous precipitation simultaneously, as a result of the aging treatment induced in a temperature range correspondent to the one of a welding process in the referred material. The microstructural characterization was performed by optical microscopy, scanning electron microscopy and transmission electron microscopy, including microanalysis, due to the nanometric nature of the precipitated phases. Discontinuous precipitation produces a lamellar structure along grain boundaries as a result of a cooperative growth between the lamellae, involving substitucional and interstitial atoms, Cr and N respectively. Continuous precipitation occurs inside grains, generating precipitates with different morphologies. Microanalysis reveals that products of both precipitation reactions grow competing for Cr. A kinetic-morphological analysis points to the non-stationary characteristic of the discontinuous precipitation, where the transformation rate diminishes until it stops completely, as aging occurs.
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Кушнерьов, О. І., and В. Ф. Башев. "Магнітні властивості багатокомпонентних сплавів системи Cu-Fe-Ni із домішками Al та Si." Thesis, Сумський державний університет, 2017. http://essuir.sumdu.edu.ua/handle/123456789/63905.
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У 2004 р були опубліковані перші роботи, присвячені створенню і дослідженню нового класу матеріалів, так званих високоентропійних сплавів (ВЕС), що можуть включати в себе до 13 основних елементів, в концентраціях від 5 до 35%. У даній роботі за допомогою вібраційного магнітометра досліджені магнітні властивості ВЕС Al0.5CuFeNi та CuFeNiSi0.5 у литому стані. При цьому встановлено, що обидва сплави є феромагнетиками із питомою намагніченістю MS відповідно 28 А·м2/кг та 37 А·м2/кг. Підвищене значення MS для сплаву CuFeNiSi0.5 вочевидь пояснюється наявністю у ньому ОЦК фази, сформованої на основі феромагнітного α-заліза.
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Chen, Shuai. "Transformation-Induced Plasticity and Deformation-Induced Martensitic Transformation of Ultrafine-Grained Metastable Austenite in Fe-Ni-C Alloy." 京都大学 (Kyoto University), 2015. http://hdl.handle.net/2433/199310.
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Овруцький, А. С. "Особливості розмірної залежності інтегрального коефіцієнта поздовжньої тензочутливості плівок сплаву Ni[80]Fe[20]." Thesis, Сумський державний університет, 2017. http://essuir.sumdu.edu.ua/handle/123456789/64714.
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У роботі наведені результати дослідження тензоефекту в плівках пермалою (Py) Ni80Fe20 в діапазоні товщин d = 10-50 нм. Тонкоплівкові зразки отримувалися методом термічного випаровування масивного матеріалу Py 79 НМ (79–80 мас. % Ni, 15–16 мас. % Fe; 4–5 мас. % Мо) зі швидкістю 0,1 нм/с на полістиролові підкладки (П). Вивчення тензорезистивних властивостей проводилося протягом 3-х циклів «навантаження ↔ зняття навантаження» у деформаційному інтервалі Δεl = 0–1 %.
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Gutierrez, Ladron de Guevara Luis A. "Studies in powder injection moulding with a PEG-PMMA composite binder using Fe-50% Ni, Fe3%Si and Fe-7%Si soft magnetic alloy powders." Thesis, University of Sheffield, 2005. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.419566.
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Kushnerov, O. I., and V. F. Bashev. "Structure and mechanical properties of Al-Co-Cr-Fe-Mn-Ni-Si-V high-entropy films obtained by splat-quenching." Thesis, Sumy State University, 2015. http://essuir.sumdu.edu.ua/handle/123456789/42650.
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The multicomponent films of Al-Co-Cr-Fe-Mn-Ni-Si-V high-entropy alloys obtained by splat-quenching from melt were investigated. Phase formation criteria for high-entropy alloys were considered. The films have a structure with body-centered cubic lattice. The value of lattice parameters of the investigated alloys suggests that the solid solutions are form on the base of Cr lattice, in view of its higher melting temperature.
The positive influence of microstrains level and dislocation density on the microhardness values of splat-quenched high-entropy alloys has been established. Improved mechanical characteristics are ensured by the strong distortion of the crystal lattice due to the differences in atomic radii of the elements.
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SPADOTTO, JULIO CESAR. "MICROSTRUCTURAL STABILITY OF ALLOY 33 (CR-FE-NI-N) AND ITS POTENTIAL TO BE SUBMITTED TO FUSION WELDING OPERATIONS." PONTIFÍCIA UNIVERSIDADE CATÓLICA DO RIO DE JANEIRO, 2015. http://www.maxwell.vrac.puc-rio.br/Busca_etds.php?strSecao=resultado&nrSeq=25345@1.
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PONTIFÍCIA UNIVERSIDADE CATÓLICA DO RIO DE JANEIROCONSELHO NACIONAL DE DESENVOLVIMENTO CIENTÍFICO E TECNOLÓGICO
O presente trabalho estuda a estabilidade microestrutural da liga 33 (Cr-Fe-Ni-N) em condições de trabalho, tendo em vista o desempenho das suas juntas soldadas em projetos industriais. Amostras desta liga seguiram um procedimento previamente programado de tratamentos térmicos de solubilização e envelhecimento isotérmico a 700 graus Celsius e 900 graus Celsius durante 1h, 10h e 100h. Nestas condições, foram identificados a ocorrência dos fenômenos de precipitação homogênea e heterogênea convencional, assim como da precipitação descontínua. A elucidação da cinética desta última é de particular interesse em virtude do efeito negativo nas propriedades mecânicas e desempenho de diversas ligas metálicas como elemento estrutural. Posteriormente, o material como recebido foi submetido ao processo de soldagem TIG autógena. Amostras da junta soldada passaram pelos tratamentos térmicos de solubilização e envelhecimento isotérmico a temperatura de 700 graus C durante 1 h, 10 h e 100 h, além de uma amostra ter sido envelhecida diretamente pós-soldagem durante 100h na temperatura de 700 graus Celsius. A caracterização microestrutural do material, a partir da condição como recebido, após tratamentos térmicos, como soldado e tratamentos térmicos pós-soldagem, foi realizada por microscopia ótica (MO), microscopia eletrônica de varredura (MEV) e microscopia eletrônica de transmissão convencional (MET) e na modalidade transmissão/varredura (STEM). Sempre que possível, microanálise qualitativa dos diferentes elementos micro estruturais foi levada a efeito por espectroscopia de dispersão de energia característica de raios-x (XEDS) acoplada ao MEV e ao MET/STEM. Foram realizados ensaios de microdureza para avaliar os efeitos da soldagem e dos tratamentos térmicos em todas as condições do material. Os resultados demonstram que tanto os precipitados homogêneos, heterogêneos em contornos de grão como as colônias de precipitação descontínuas são ricos em Cr. Nesta última, caracterizada por uma estrutura lamelar crescendo cooperativamente com a migração dos contornos de grão de alto ângulo, os precipitados lamelares parecem ter incorporado nitrogênio por difusão intergranular, formando Cr2N. Este fenômeno foi também detectado na junta soldada após envelhecimento direto a 700 graus Celsius durante 100h. Os resultados dos ensaios de dureza mostram o endurecimento por precipitação na liga 33 envelhecida em ambas as temperaturas utilizadas, diferentemente da junta soldada que apresentou discreta alteração de microdureza, mesmo após os tratamentos térmicos aplicados.
This work studies the microstructural stability of alloy 33 (Fe-Cr-Ni-N) aiming at improving the performance of welded joints under in working conditions. Samples of this alloy followed a previously programmed procedure of homogenization and isothermal aging heat treatment at 700 degrees C and 900 degrees C for 1h, 10h and 100h. Under these conditions, the occurrence of homogeneous and heterogeneous conventional precipitation, as well as the discontinuous precipitation phenomena, were identified. The elucidation of the kinetics of the latter is of particular interest because of the well-known negative effect on the mechanical properties and performance of the several alloys applied as structural component. Subsequently, the as-received material was submitted to TIG welding process. Samples of the weld joints followed the same heat treatment schedule of homogenization and isothermal aging temperature of 700 degrees C for 1h, 10h and 100h. In addition, a welded sample was directly aged at this temperature for 100h at 700 degrees C. Microstructural characterization of the material, from the as received condition, to all post-heat treatment, as-welded and post-welding conditions was performed by optical microscopy (OM), scanning electron microscopy (SEM) and transmission electron microscopy, in the conventional (CTEM)and scanning/transmission (STEM) modes. Whenever possible, qualitative microanalysis of different microstructural elements was carried out by characteristic x-ray energy dispersive spectroscopic (XEDS) coupled to SEM and TEM/STEM. Micro-hardness tests were conducted to evaluate the effects of welding and heat treatment on the materials under all above mentioned conditions. The results demonstrate that both the homogeneous and heterogeneous precipitates at grain boundary as well as colonies of discontinuous precipitation are rich in chromium. In the latter, characterized by a lamellar structure growing cooperatively with high angle grain boundary migration, the lamellar precipitates appear to have nitrogen incorporated by inter granular diffusion mechanism, forming Cr2N.This phenomenon was also detected in the welded joint aged at 700 degrees C for 100 h. The results of the hardness tests show the precipitation hardening effect on the alloy aged at 33 at both temperatures , contrary to the welded joints where no significant change in micro-hardness were detected even after the application of heat treatments.
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FARIA, MARCUS VINICIUS COMODO LAURIA DE. "APPLICATION POTENTIAL OF AN FE-C-NI ALLOY IN FLANGED CONNECTION OF END FITTING OF FLEXIBLE PIPE UNDER CRYOGENIC CONDITIONS." PONTIFÍCIA UNIVERSIDADE CATÓLICA DO RIO DE JANEIRO, 2016. http://www.maxwell.vrac.puc-rio.br/Busca_etds.php?strSecao=resultado&nrSeq=29715@1.
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PONTIFÍCIA UNIVERSIDADE CATÓLICA DO RIO DE JANEIROCOORDENAÇÃO DE APERFEIÇOAMENTO DO PESSOAL DE ENSINO SUPERIOR
PROGRAMA DE SUPORTE À PÓS-GRADUAÇÃO DE INSTS. DE ENSINO
Durante o tempo em serviço, estruturas e componentes de equipamentos podem falhar e causar acidentes. Isto geralmente conduz a danos materiais podendo, ainda, causar perda de vidas humanas e danos ambientais. Frequentemente, os eventos danosos são originários de falhas de materiais e de fabricação, sobrecargas não previstas ou outros problemas oriundos do tempo de operação ou deficiência de manutenção de um componente. Neste estudo, com base numa análise de propagação de trinca superficial submetida a carregamento, se avaliou a integridade de um flange da conexão de topo de uma linha flexível, sob condições criogênicas de operação. Quando em serviço, a falha deste conector pode ocasionar interrupções na produção, dano a equipamentos e meio ambiente, bem como fatalidades em plataformas offshore de petróleo. As linhas (dutos) flexíveis utilizadas para injetar gás CO2 nos reservatórios de petróleo no país trabalham submetidas a elevadas pressões internas (da ordem de 10.000 psi), o que aumenta o risco de falha do componente. Além disto, a selagem da conexão flangeada pode falhar e provocar um vazamento de fluido gasoso, proporcionando uma queda acentuada da temperatura local e potencializando a fratura frágil do componente. O cenário proposto para o estudo foi relacionado a possível falha na vedação do anel BX, localizado entre a conexão da linha flexível e a plataforma de petróleo. A metodologia foi dividida em duas etapas: a primeira corresponde à análise global linear elástica do conector na ausência de trincas e baseada no método de elementos finitos (MEF). Na segunda etapa da análise, se introduziu uma trinca no conector na região com os maiores níveis de tensão e onde é possível realizar ensaio por líquido penetrante. Assim, o estudo se concentrou na conexão flangeada do conector, adotando como um aço com 9 por cento de níquel em sua composição química, liga ferrosa de larga aplicação em tanques de armazenagem de GNL. Se buscou avaliar a resistência à fratura do material através da associação de condições severas de carregamento, baixas temperaturas e tamanho de trinca em flanges de dutos flexíveis, conforme critério severizado da norma API 6A. Desta maneira, se espera contribuir para que a indústria offshore de petróleo tenha mais uma opção de material para ser adotado na fabricação de conectores de topo das linhas flexíveis que trabalhem em condição criogênica.
During the time in service, structures and equipment components can fail and cause accidents. This usually leads to damage and may also cause loss of human lives and environmental damages. Often, harmful events are originated from materials and manufacturing faults, unforeseen overloads or other problems arising from the operation time or component maintenance deficiencies. In this study, based on the analysis of surface crack propagation under loading, was assessed the integrity of a top connecting flange of a flexible line operation under cryogenic conditions. When in service, the failure of this connector may cause production disruptions, damages to the equipment and the environment, as well as human fatalities on offshore oil platforms. In Brazil, flexibles lines (ducts) used to inject CO2 gas in oil reservoirs work subjected to high internal pressures (of the order of 10,000 psi), which increases the risk of a component failure. Moreover, the damaged flange may cause leakage of gaseous fluid resulting in very low local temperatures and resulting in brittle fracture enhancing of the component. The scenario proposed in this study is related to a possible seal BX ring failure which is located between the flexible line connection and the oil platform. The methodology was divided into two stages: the first corresponds to the linear elastic global analysis of the connector in the absence of cracks and based on the finite element method (FEM). In the second stage of analysis, it introduced a crack on the connector in the region with the highest stress levels and where it is possible to test for penetrant. Thus, the study focused on the flange connection connector, adopting as a steel with 9 per cent nickel in its chemical composition, ferrous alloy wide application in LNG storage tanks. He sought to evaluate the fracture resistance of the material through the combination of severe loading conditions, low temperatures and 9 cracks in flanges of flexible ducts as severe criteria standard API 6A standard. Thus, it is expected to contribute to the offshore oil industry has one more material option to be adopted in the manufacture of top connectors of the flexible lines working in cryogenic condition.
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Sato, Yu. "Thin film microscopy of Pb on Ge(111) phase transitions and Fe[x]Ni₍₁₋[x]₎ on Cu(111) magnetic surface alloy /." For electronic version search Digital dissertations database. Restricted to UC campuses. Access is free to UC campus dissertations, 2005. http://uclibs.org/PID/11984.
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Duffield, M. E. "Novel metal-metal oxide thick film heating elements produced by dual-stage flame spray processing of a gas atomised Ni-Cr-Fe alloy." Thesis, University of Liverpool, 2017. http://livrepository.liverpool.ac.uk/3008760/.
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OSTROWSKA, MARLENA. "Thermodynamic modelling and experimental validation of High Entropy Alloys containing Al, Co, Cr, Fe, Mo, Ni, Ta and W for high-temperature applications." Doctoral thesis, Università degli studi di Genova, 2021. http://hdl.handle.net/11567/1046937.
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The aim of the current project is to contribute to the design of novel High Entropy Alloys (HEAs) which meet targeted industrial needs, for instance the request for new high-temperature alloys.
HEAs attracted a lot of attention due to their promising high temperature mechanical performance. Taking into account a very wide range of alloys that fall into this group of materials, using only experimental investigations would be insufficient in finding new compositions with attractive properties.
The objective is achieved by thermodynamic modelling of the Al-Co-Cr-Fe-Mo-Ni-Ta-W system, through the CALPHAD method, in order to predict the best candidate elements and compositions which can give the required structure.
The reliable and self-consistent database is obtained by assessing several important ternary systems and by adopting published assessments, if they were compatible with the models selected in this work.
The reliability of the database is verified with experimental measurements performed during this work regarding the reference system Al-Co-Cr-Fe-Ni, as well as the critically selected published experimental data regarding several other multicomponent systems containing Mo and W.
The synergy between modelling and experimental validation produce a highly reliable thermodynamic database which allows to screen and quickly identify high performance compositions, with a significant reduction in time and costs with respect to traditional trial and error experiments.
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Bouhouch, Lahoussine. "Élaboration des couches d'alliages NI-FE par voie électrolytique : Études électrique, magnétique et structurale." Nancy 1, 1988. http://www.theses.fr/1988NAN10089.
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Mécanismes, caractéristiques et facteurs influant le dépôt électrolytique. Techniques d'élaboration et de dosage du fer dans les alliages NI-FE déposés. Influence des conditions opératoires sur la nature et composition des alliages élaborés. Étude des propriétés électriques magnétiques et de l'influence des traitements thermiques sur la structure des alliages
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Simonetta-Perrot, Marie-Thérèse. "Étude de l'influence d'éléments traces (C, S, B, Al, N) sur la ductilité à chaud de l'alliage austenitique Fe-Ni 36% (INVAR) de haute pureté." Grenoble INPG, 1994. http://www.theses.fr/1994INPG4209.
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Pour cerner les mecanismes d'endommagement a l'origine du creux de ductilite de l'invar vers 600c, nous utilisons un materiau modele fe-ni 36% de haute purete dope par des elements traces. Quatre groupes d'alliages sont elabores afin d'isoler les effets du soufre seul, du soufre en presence de precipites aln ou bn, et du soufre en presence de bore, sur la ductilite, les modes de rupture, l'endommagement intergranulaire et les mecanismes de deformation. La repartition des impuretes est caracterisee par meb, met et aes. Nous avons mis au point une methode pratique de quantification des segregations par aes, pour degager le lien entre les segregations intergranulaires et superficielles du soufre et la fragilite intergranulaire. Nous concluons que lorsque le taux de segregation du soufre est superieur a 0. 65, le soufre suffit a fragiliser les joints de grains des 20c. Par contre, aux faibles taux de segregation du soufre, le glissement intergranulaire est necessaire a la cavitation ce qui explique la chute de ductilite vers 500c. De plus, la segregation superficielle du soufre sur les cavites creees contribue a accelerer la croissance de celles-ci. De fins precipites aln ou bn aux joints de grains reduisent le taux minimum de segregation necessaire a la fragilisation et aggravent la fissuration. Le bore libre ameliore la ductilite a toutes les temperatures. Son action est liee a sa segregation aux interfaces, qui reduit les vitesses de germination et croissance des cavites
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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.
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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.
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Abdu, Yassir Ahmed Mohamed. "Mössbauer Spectroscopy of Meteoritic and Synthetic Fe-Ni Alloys." Doctoral thesis, Uppsala University, Department of Earth Sciences, 2004. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-3969.
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This thesis reports on the results of investigating Fe-containing minerals in meteorites, with focus on Fe-Ni minerals and their magnetic properties, along with some synthetic Fe-Ni analogues. The New Halfa meteorite, which fell in Sudan 1994, has been studied using Mössbauer spectroscopy, X-ray diffraction, and electron microprobe analysis techniques, and classified as an ordinary L-type chondrite of petrologic type 4. Mössbauer spectra of taenite-enriched samples from the metal particles of the New Halfa (L4) and Al Kidirate (H6) meteorites identify the following γ (fcc) Fe-Ni phases: the ferromagnetic atomically ordered taenite (tetrataenite) with ~ 50 at % Ni, the ferromagnetic disordered taenite with ~ 50 at % Ni, the low-Ni (~ 25 at %) paramagnetic taenite (antitaenite). The presence of the superstructure of tetrataenite is confirmed by synchrotron X-ray diffraction.
Fe-rich γ (fcc) Fe-Ni alloys with compositions Fe79Ni21, Fe76Ni24, and Fe73Ni27, which serve as synthetic analogues of antitaenite, are prepared by mechanical alloying and subsequent annealing at 650 °C. The Mössbauer results indicate that these alloys are inhomogeneous and contain a high moment (HM) ferromagnetic Ni-rich phase (> 30 at % Ni) and a low moment (LM) paramagnetic Fe-rich phase, which orders antiferromagnetically at low temperature. The coexistence of these phases is attributed to phase segregation occurring on short range, probably nanometer scale, consistent with the Fe-Ni phase diagram below 400 °C where there is a miscibility gap associated with a spinodal decomposition in alloys with < 50 at % Ni.
The combined high field Mössbauer spectroscopy and SQUID magnetometry results on these alloys at room temperature indicate large induced local magnetic moments in the paramagnetic part of the sample, which increases with increasing the Ni content. The results, when compared with the high field Mössbauer results on antitaenite from the metal particle of Al Kidirate and New Halfa meteorites may be used to estimate the Ni content of antitaenite in meteorites.
High pressure 57Fe Mössbauer spectroscopy measurements up to ~ 41 GPa have been carried out at room temperature using the diamond anvil cell (DAC) technique in order to investigate the magnetic properties of γ (fcc) 57Fe53Ni47 alloy. The results indicate a pressure induced Invar effect at ~ 7 GPa and a non-magnetic or paramagnetic state above 20 GPa, demonstrating the volume dependence of the magnetic moment of γ (fcc) Fe-Ni alloys.
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Walker, Ian Thomas. "Transformations in (Fe, Ni)-based amorphous and nanostructured alloys." Thesis, University of Cambridge, 2001. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.621326.
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Sorsh, Frans. "Assessment of creep damage in Fe-Ni-Cr alloys." Thesis, KTH, Hållfasthetslära (Avd.), 2019. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-259516.
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It is only a matter of time before components working in high temperature environments fail due to creep. Design for creep is therefore of vital importance to maximize the lifetime of components and reduce costs that may arise from maintenance and replacement of components. This thesis aims to use metallographical methods and finite element modeling to assess creep damage in a hydrogen reformer. The decommissioned reformer, made of Fe-Ni-Cr alloys, was investigated thoroughly via replica testing, hardness measurements as well as finite element modeling of the welds. An extended literature review was performed to gain a better understanding of creep in Fe-Ni-Cr alloys, welds and the modeling of creep generally. The microstructures of samples from the reformer were analyzed and mapped out in terms of creep damage which were then compared to a creep analysis of the welds with a simulation time of 100 000 h. The FE results yielded high stresses and creep strains with a maximum of 0.95% in the boundaries of the welds which gave realistic representations of strain distributions when compared to the metallographical results. Hardness measurement indicated that a relatively narrow zone with altered mechanical properties is present along the weld boundaries. This area, called the heat affected zone, was found to be most affected by creep with microcracks reaching maximum lengths of 2 mm. The creep strains obtained from simulation did not fall in line with the observed creep damage, it was thus concluded that a material model that considers tertiary creep would yield a more realistic representation in FEM for Fe-Ni-Cr alloys.Det är bara en tidsfråga innan komponenter som arbetar i högtemperaturförhållanden misslyckas pga kryp. Att designa med avseende på kryp är därmed viktigt för att maximera livslängden och reducera kostnader som kan komma från underhåll och från utbyte av komponenter. I detta examensarbete används metallografiska metoder och finita element modellering för att bedöma krypskador i en vätgasreformer. Vätgasreformern, som är tillverkad i Fe-Ni-Cr legeringar, togs ur drift och undersöktes metallografiskt med hjälp av replikprovning och hårdhetsprovning samt med finita element modellering av svetsar. En djupgående litteraturstudie utfördes för att öka förståelsen av kryp, specifikt i Fe-Ni-Cr legeringar och även modellering av kryp generellt. Mikrostrukturen från utvalda provbitar undersöktes och krypskador kartläggdes för att sedan jämföra med en krypanalys av svetsarna där 100 000 timmars kryp simulerades. Krypanalysen resulterade i höga spänningar och kryptöjningar upp till maximalt 0.95% i svetsgränserna vilket gav realistiska representationer av töjningsdistributionen jämfört med metallografiska resultaten. Hårdhetsmätningar indikerade att ett smalt område med förändrade mekaniska egenskaper fanns utmed svetsgränserna. Detta område, den värmepåverkade zonen, var mest utsatt för krypskador med mikrosprickor uppemåt 2 mm i längd. Kryptöjningar som erhölls från simuleringen gav inte en tillräckligt bra uppskattning av kryptöjningarna – de krypskador som observerades motsvarar lokalt högre töjning. Slutsatsen är att en materialmodell som tar hänsyn till tertiärkryp skulle i det här fallet ge en mer realistisk representation i FEM för Fe-Ni-Cr legeringar.
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Ispas, Adriana. "Electrochemical Phase Formation of Ni and Ni-Fe Alloys in a Magnetic Field." Doctoral thesis, Saechsische Landesbibliothek- Staats- und Universitaetsbibliothek Dresden, 2007. http://nbn-resolving.de/urn:nbn:de:swb:14-1194000718076-46815.
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The aim of this work was to investigate the effects that a magnetic field can induce during the electrodeposition of Ni and Ni-Fe alloys. Special regard was given to mass transport controlled effects. Magnetic field effects on the nucleation and growth of ferromagnetic layers and on the properties of electrodeposited layers (like grain size, texture, morphology or roughness) were investigated. The influence of a magnetic field on the magnetic properties of Ni layers and on the composition of Ni-Fe alloys was also studied. Nucleation and growth of thin Ni layers on gold electrodes under a superimposed magnetic field were analysed in-situ with the Electrochemical Quartz Crystal Microbalance technique. Three theoretical models were chosen for characterizing the Ni nucleation: Scharifker-Hills (SH), Scharifker-Mostany (SM) and Heerman-Tarallo (HT). The AFM images proved that more nuclei appear in a magnetic field in the case that the Lorentz force and the natural convection act in the same direction. From all the models, the HT model gave the best agreement with the AFM results. When the Lorentz force and the natural convection act in the same direction, an increase of the Ni partial current with the magnetic field was obtained. When they act in opposite directions, the Ni current was influenced just at the beginning of deposition (first 10 seconds). At longer times, the magnetic field has no effect on the Ni current. However, the total current (jNi+jHER) decreases with the magnetic field. In the absence of a macroscopic MHD convection, the Ni current decreases with the magnetic field the first 10-15 seconds of deposition. On longer time scales no influence of the magnetic field could be noticed for this configuration. When the magnetic field was applied perpendicular to the electric current, an increase of the hydrogen evolution reaction (HER) with the magnetic flux density was noticed. Hydrogen reduction is mass transport controlled. Therefore, the magnetic field will increase the limiting current of the HER. Optical microscopy images showed that the hydrogen bubbles were circular in the absence of the MHD convection and that they presented a tail when a Lorentz force was present. The direction of the tail depends on the net force induced by the natural and MHD convections. The interplay between the natural and MHD convections proved to be important during Ni-Fe alloy deposition, too. When the Lorentz force and the natural convection act in the same direction, an increase of the Fe content of the alloys with the magnetic field was observed. When the Lorentz force was perpendicular to the natural convection, no significant changes were observed in the composition of the layers. The alloy composition did not change with the magnetic field when the electric current was parallel to the magnetic field lines. Two surfactants were used in the case that Ni was electrodeposited from a sulfamate bath: SDS and sulfirol 8. The Ni layers obtained from a sulfamate bath with sulfirol 8 presented larger grains compared to the layers deposited from a bath free of surfactants. This increase of the grain size was attributed to the incorporation of the surfactant in the deposit. Coarser layers were obtained in a magnetic field (applied perpendicular to the electric current) when the electrodeposition was done from an electrolyte with surfactants. The number of grains increased with the magnetic field for the Ni layers electrodeposited from a bath free of surfactants and for a bath with SDS. As a consequence, the grain size decreased. In the case of the electrolyte with sulfirol 8, the number of grains decreased with the magnetic field, and their size increased. For the Ni-Fe alloys, which contained less than 10 at% Fe, the preferred crystalline orientation changes from (220), in the absence of a magnetic field, to (111), (when the magnetic field was applied perpendicular to the electric current). When the magnetic field lines were parallel to the electric current, both the (111) and (220) textures were preferred in almost the same proportion. As a general conclusion of this work it can be said that by choosing the right experimental condition, one can improve the morphology and the properties of the deposited layers by applying a magnetic field. At the same time, the mass transport processes can be influenced by a magnetic field.
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Turi, Tibor. "Thermal and thermodynamic properties of fully dense nanocrystalline Ni and Ni-Fe alloys." Thesis, National Library of Canada = Bibliothèque nationale du Canada, 1997. http://www.collectionscanada.ca/obj/s4/f2/dsk3/ftp04/nq20593.pdf.
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Garimella, Narayana. "Multicomponent interdiffusion in austenitic Ni-, Fe-Ni-base alloys and L1₂-Ni₃Al intermetallic for high-temperature applications." Orlando, Fla. : University of Central Florida, 2009. http://purl.fcla.edu/fcla/etd/CFE0002521.
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Othen, Peter. "A study of copper precipitation in Fe-Cu and Fe-Cu-Ni model alloys." Thesis, University of Oxford, 1992. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.333362.
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Koseki, Toshihiko 1958. "Undercooling and rapid solidification of Fe-Cr-Ni ternary alloys." Thesis, Massachusetts Institute of Technology, 1994. http://hdl.handle.net/1721.1/12040.
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Flores, Carlos D. (Carlos Daniel). "Evaluation of radiation induced segregation in Fe-Ni-Cr alloys." Thesis, Massachusetts Institute of Technology, 1994. http://hdl.handle.net/1721.1/44597.
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Thesis (M.S.)--Massachusetts Institute of Technology, Dept. of Nuclear Engineering; and, (M.S.)--Massachusetts Institute of Technology, Dept. of Materials Science and Engineering, 1994.Includes bibliographical references.
by Carlos D. Flores.
M.S.
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Crozet, Coraline. "Equilibres de phases et microstructures d'alliages CU-FE-NI riches en FE." Thesis, Grenoble, 2011. http://www.theses.fr/2011GRENI015/document.
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Ce travail a pour but l’acquisition de connaissances fondamentales dans les équilibres de phases et les transformations de phases des alliages ternaires contenant du fer, du nickel et du cuivre.Cette étude est composée de trois parties : la première est consacrée aux équilibres de phase entre600°C et 1000°C dans le coin riche en fer du système ternaire Cu-Fe-Ni, la seconde concerne l’analyse des transformations de phases dans des alliages modèles suivant deux vitesses de refroidissement et la troisième étudie les alliages industriels.Cette approche expérimentale est appuyée par des calculs thermodynamiques. Une comparaison est effectuée avec les données issues de la littérature. Les sections isothermes à 600°C, 800°C et1000°C ont été reconfirmées. Les domaines triphasés αFe/γFe/γCu ont été déterminés à 600°C et800°C et semblent décalés vers de plus fortes teneurs en Ni. La lacune de miscibilité est moins étendue que celle calculée et ce particulièrement du côté du binaire Cu-Ni.Les transformations de phase γ→α apparaissant lors du refroidissement d’alliages Fe-xCu-10Ni et Fe-10Cu-xNi (0This work aims in getting fundamental knowledge of phase equilibria and microstructures of ternary alloys containing copper, nickel and iron. The thesis is composed of three parts: a first part is devoted to phase equilibria in the Fe-rich corner of the ternary Cu-Fe-Ni system between 600°C and 1000°C, a second part is devoted to the microstructures in these materials for model alloys, for two cooling rates and a third part is devoted to industrial alloys.Phase equilibria of the system are investigated in the range 600-1000°C using diffusion multiples in conjunction with selected equilibrated alloys. This experimental approach is supplemented by thermodynamic calculations. A comparison is drawn with data reported in the literature. The isothermal sections at 600°C, 800°C and 1000°C have been reconfirmed. The three-phase regions αFe/γFe/γCu are determined at 600°C and 800°C and appear shifted to a higher Ni content. The miscibility gap is narrower than the calculated, particularly on the Cu-Ni binary sides.Austenite/ferrite phase transformations occurring on cooling in Fe-xCu-10Ni and Fe-10Cu-xNi alloys,0
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Tappin, David Keith. "The characterisation of displacement cascades in austenitic Fe-Cr-Ni alloys." Thesis, University of Liverpool, 1991. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.317254.
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Watson, Maxine. "Phase stability, constitution and precipitation effects in Fe-Ni-Cr alloys." Thesis, Sheffield Hallam University, 1990. http://shura.shu.ac.uk/20503/.
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A study of the constitution, transformation and precipitation effects in ternary Fe-Cr-Ni alloys and quaternary Fe-Cr-Ni-X alloys containing Mo, Nb, Ti, and Si was carried out. A systematic approach was adopted so that the microstructural effects observed as a result of ageing the selected iron base ternary alloys could be directly compared to the quaternary alloys. A series of ageing curves were plotted for the six ternary alloys over the temperature range 400°-900°C and for the ten quaternary alloys in the temperature range 650°-850°C. Optical and electron metallography were used to study the transformation and precipitation of intermetallic phases and carbides in the aged microstructures. The transformation of delta ferrite to sigma phase in a duplex (gamma+delta) ternary alloy was studied. The transformation was preceded by the precipitation of a cellular structure which formed on the delta/gamma grain boundaries and consisted of M23C6 and new austenite. A complex transformation product, which resembled a region of imiscibility, then formed at the delta/(gamma + M23C6) interface, this product consumed the delta ferrite grain, eventually transforming to sigma phase and new austenite. The alpha' phase, more commonly referred to as 475°C embrittlement, was also observed precipitating in the delta ferrite grains in two of the iron based ternary alloys in the temperature region 400°-500°C. Overageing of the alpha' precipitates after 1000 hours at 500°G was accompanied by the precipitation of a rod like austenite. The elements 2%Mo, 1%Nb, 1/4%Ti and 1% and 2%Si were added totwo Fe-Ni-Cr base alloys. One alloy was an austenitic (20Cr,23Ni) and the other was a transformable alloy (18Cr, 7Ni). The quaternary element additions had no effect on the constitution of the austenitic ternary alloy. However the addition of Mo to the 18Cr, 7Ni ternary alloy caused the transformation of delta ferrite to sigma phase over ageing temperature range 650°-850°C. The addition of Si moved the constitution of the ternary alloy further into the gamma+delta phase field, a small amount of sigma phase was observed in the 2%Si quaternary alloy on ageing at 650°C for 1000 hours. Irradiation damage studies were performed using High Voltage Electron Microscope and Variable Energy Cyclotron. The effect ofthe quaternary alloying additions Mo, Si, and Nb on the voidswelling behaviour of a 20Cr, 23Ni alloy were studied using 46MeV Ni6 ions in the Variable Energy Cyclotron, irradiating to a total dose of 10dpa at 550°C. All additions reduced void swelling, the largest reduction was observed in the Si containing allov. The Insert A Thermal ageing showed the presence of M23C6 the amount of which increased with increasing ageing temperature. No delta ferrite was observed in these alloys.
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Тищенко, Костянтин Володимирович, Константин Владимирович Тищенко, Kostiantyn Volodymyrovych Tyshchenko, and Т. М. Шабельник. "Структура та фазовий стан плівкових сплавів на основі Ni і Fe." Thesis, Видавництво СумДУ, 2012. http://essuir.sumdu.edu.ua/handle/123456789/27666.
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Erdem, Derya. "Microwave Sintering And Characterization Of Soft Magnetic Powder Metallurgical Ni-fe Alloys." Master's thesis, METU, 2011. http://etd.lib.metu.edu.tr/upload/12613550/index.pdf.
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In this study, prealloyed austenitic stainless steel and premixed soft magnetic Ni-Fe permalloy compacts were consolidated through microwave and conventional sintering routes at combinations of various sintering temperatures and compaction pressures. Sintered alloys were characterized in terms of their densification, microstructural evolution as well as mechanical and magnetic properties. The effect of sintering method in terms of the applied sintering parameters on the final properties of the compacts were investigated in a comparative manner. It was determined that microwave sintered permalloys are superior compared to their conventionally sintered counterparts in densification response, microstructural characteristics such as pore shape and distribution as well as mechanical properties for both austenitic stainless steel and permalloy compacts. However, permeability of the microwave sintered permalloys was inferior to their conventionally sintered counterparts in some cases due to microstructural refinement associated with microwave sintering route.
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Keramidas, Paris. "Process microstructure property studies of powder metallurgy Al-Fe-Ni base alloys." Thesis, University of Surrey, 1998. http://epubs.surrey.ac.uk/843047/.
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Four alloys with nominal compositions Al-8Fe-4Ni, Al-8Fe-4Ni-2,5Zr, Al-8Fe-4Ni-2.5Zr-1Mo and Al-8Fe-4Ni-2.5Zr-2V-1Mo (wt%) were produced in the form of wedge shaped ingots by chill casting in a copper mould and in powder form by high pressure gas atomisation using Helium as the atomising gas. Sub-45, sub-50 or +50-100 mum powder size fractions were canned and degassed at 573K. The first two alloys were consolidated by hot extrusion at 573K and ER=18:1 and 25:1. The third alloy could be extruded at 698K and ER=5:1 while the powders of the fourth alloy were hot pressed at 623K because of difficulties with extrusion. The microstructures at the tips of the wedge castings could be related to those of the atomised powder particles. Rapid solidification suppressed the formation of Al3Fe, Al12Mo and A111V in the tips of the wedge castings and m powder particles up to 200 mum diameter, where the microstructures consisted only of a-Al and Al9FeNi, with some week evidence for possible formation of Ll2-Al3Zr in the larger powder particles. Two types of microstructures were observed in the powder particles: Zone A, consisting of mu-Al solid solution or microcellular mu-Al+Al9FeNi eutectic structures or Zone B consisting of mu -Al+Al9FeNi dendritic structures. The transition from Zone A to Zone B microstructres shifted to smaller powder particle sizes (from 20 mum to less than 10 mum) or smaller thickness (< 300mum) of the wedge shaped ingots with increasing solute addition to the first alloy. In all cases the Al9FeNi phase formed under RS conditions had Fe/Ni=2 with solubility for the TM alloying additions. The microstructure of the extruded first alloy exhibited bands of finer and coarser structure without any remaining undeformed powder particles. The banding effect was far less pronounced m the extrusions of the second alloy, where the distribution of the Al9FeNi phase was more homogeneous but there was some evidence of non-fully deformed powder particles (< 5vol%), which were always small (< 10 mum diameter) and hard particles exhibiting the Zone A microstructure of the RS powders. In addition to mu-Al and Al9FeNi, there was a very small volume fraction of Many undeformed particles, which were associated with extended porosity, were also present in the extrusion of the third alloy but bands of finer and coarser structure were not visible. The hot pressed powders of the fourth alloy were at best partially deformed and had retained their RS microstructure with some present in the as pressed microstructure. The microstructures of the consolidated alloys were stable after heat treatment at 673K consisting of mu-Al, Al9FeNi and Ll2-Al3Zr and with the Al9FeNi phase experiencing some coarsening after 1000h, especially in the first alloy, where also the banded structure disappeared after prolonged treatment. The Zone A microstructure was significantly harder than Zone B. The additions of Zr, Mo and V resulted to increases in hardness of 20%, 60% and 110% over the first alloy in the as extruded or hot pressed conditions. After 1000h at 673K the hardness of the first alloy had dropped by 28% and 24% for the 18:1 and 25:1 extruded materials respectively, with the corresponding values for the second alloy being 17% and 11%. The hardnesses of the third and fourth alloys had dropped by about 15%. Higher tensile properties were achieved in the alloys extruded with ER=18:1. The ductilities of all alloys were poor owing to the high volume fractions of Al9FeNi. The mu-Al matrix of the first alloy extruded at ER=18:1 and 25:1 had a fibre texture with crystallographic directions parallel to the axis of the bar. The texture became stronger after heat treatment and consisted of a major fibre. Other minor components such as were also detected. Then- intensity was however fairly small when compared to . On the contrary, although the processing parameters were similar, the texture in the as-extruded bar of the second alloy (ER=18:1 and 25:1) was almost random.
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Wise, P. "Investigation of the dHvA in Pd, Pd(Ni) and Pd(Fe) alloys." Thesis, University of Sussex, 1987. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.379442.
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Matsumoto, Jun. "Electrochemistry of intermetallic phases of Ni-Cr-Fe alloys in aqueous environment." Thesis, Massachusetts Institute of Technology, 1991. http://hdl.handle.net/1721.1/13439.
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Liu, Ning-Uan, and 呂寧遠. "Electronic structure, magnetization and magnetocrystalline anisotropy energy of Fe,Co,Ni and Ni-Fe alloy monolayers." Thesis, 2004. http://ndltd.ncl.edu.tw/handle/90693332395684990270.
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Giallonardo, Jason. "Structure and Properties of Electrodeposited Nanocrystalline Ni and Ni-Fe Alloy Continuous Foils." Thesis, 2013. http://hdl.handle.net/1807/43571.
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This research work presents the first comprehensive study on nanocrystalline materials produced in bulk quantities using a novel continuous electrodeposition process. A series of nanocrystalline Ni and Ni-Fe alloy continuous foils were produced and an intensive investigation into their structure and various properties was carried out. High-resolution transmission electron microscopy (HR-TEM) revealed the presence of local strain at high and low angle, and twin boundaries. The cause for these local strains was explained based on the interpretation of non-equilibrium grain boundary structures that result when conditions of compatibility are not satisfied. HR-TEM also revealed the presence of twin faults of the growth type, or “growth faults”, which increased in density with the addition of Fe. This observation was found to be consistent with a corresponding increase in the growth fault probabilities determined quantitatively using X-ray diffraction (XRD) pattern analysis.
Hardness and Young’s modulus were measured by nanoindentation. Hardness followed the regular Hall-Petch behaviour down to a grain size of 20 nm after which an inverse trend was observed. Young’s modulus was slightly reduced at grain sizes less than 20 nm and found to be affected by texture. Microstrain based on XRD line broadening was measured for these materials and found to increase primarily with a decrease in grain size or an increase in intercrystal defect density (i.e., grain boundaries and triple junctions). This microstrain is associated with the local strains observed at grain boundaries in the HR-TEM image analysis. A contribution to microstrain from the presence of growth faults in the nanocrystalline Ni-Fe alloys was also noted. The macrostresses for these materials were determined from strain measurements using a two-dimensional XRD technique. At grain sizes less than 20 nm, there was a sharp increase in compressive macrostresses which was also owed to the corresponding increase in intercrystal defects or interfaces in the solid.
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Tsai, Chia-Cheng, and 蔡嘉正. "Improvement on the Homogenization of Ni in Fe-Ni Sinter-Hardening Alloy Steels." Thesis, 2007. http://ndltd.ncl.edu.tw/handle/10711636778502350158.
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碩士臺灣大學
材料科學與工程學研究所
96
Metal injection molding (MIM) process has many advantages in making small parts with complicated shapes over the press-and-sinter process and other manufacturing processes. The MIM parts usually must attain high sintered densities and good mechanical properties through high temperature sintering and heat treatment. However, the quenching process will cause problems in distortion and dimensional control. Thus, sinter-hardening process has become a focus of recent MIM industries. In this study, compositions and processing parameters of Fe-8Ni MIM 2700 alloys were adjusted in order to improve the mechanical properties of the sinter-hardened parts without the need of quenching. The results show that fine Ni powders reduced the diffusion distance and improved the homogeneity of Ni and C in the matrix. The addition of Cr also had similar effect. It was found from the carburization test of Fe-Ni alloys that the presence of Cr helped reduce the repulsion effect between carbon and nickel. Thus, the homogeneity of C and Ni was improved and the mechanical properties were enhanced. The use of prealloyed powder showed no improvement due to the decrease of sintered density when the same sintering temperature was used despite that the Ni was uniformly distributed. The employment of cryogenic treatment after sintering caused transformation of the retain austenite to martensite and thus could increase the tensile strength and hardness.
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Li, Li. "Deformation Study of Nanocrystalline Ni-Fe Alloy using Synchrotron Diffraction." 2010. http://trace.tennessee.edu/utk_graddiss/820.
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This dissertation addresses two critical issues in the deformation of nc metals and alloys: (1) A stress-induced genuine grain growth after the plastic deformation rather than just a change of the grain shape; (2) A systematically quantitative study of micrsostructural evolution during the plastic deformation.
These two critical issues point to the deformation of nc materials with the average-grain sizes within the range of 10 to 50 nm, which is the most interesting and controversial region in the current time. The current study provides a systematic and detailed microstructural evolution for this region, which is definitely beneficial for the investigation of the deformation mechanism in this region, especially for the simulation.
The main experimental and data-analysis methods employed in this research are synchrotron high-energy X-ray diffraction, X-ray line profile analysis, and texture analysis. The combination of these methods is beneficial to the accurate microstructural interpretation of the bulk materials.
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LIN, YONG-LONG, and 林永隆. "Phase transformation in an Fe-Al-Mn-Ni-C alloy." Thesis, 1988. http://ndltd.ncl.edu.tw/handle/82497387736752004549.
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GU, ZE-ZHONG, and 璩澤中. "Phase transformation in an Fe-Al-Mn-Ni-Cr-C alloy." Thesis, 1988. http://ndltd.ncl.edu.tw/handle/85542888008912917377.
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Gu, Shao-Ming, and 谷紹民. "Synthesis of Large-Area Graphite Layer from Fe-Ni-Cu Alloy." Thesis, 2011. http://ndltd.ncl.edu.tw/handle/x369dh.
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碩士國立臺北科技大學
材料科學與工程研究所
99
This research was using the liquid phase of Fe-Ni-Cu alloy to dissolve graphite powder; precipitate then synthesis to a large-area graphite layer on the surface of the alloy. The research used a sintering vacuum at 1350 ℃ for up to 5 hours. To observe the interaction of Fe-Ni-Cu with carbon at different isothermal times, using samples of 1.5C-Fe58.45Ni25.05Cu15 (wt%), lead to the investigation of the graphite layer growth mechanism. According to this research, copper had played an important role of controlling the segregation of carbon. The growth rate and nucleation had been elevated dramatically due to the existence of copper at a small amount. The content distribution range (carbon content 1.5 wt% to 2.5 wt%, and the copper content 1.0 wt% to 30 wt%) of carbon and copper could lead to the ideal result expected which is the large-area graphite layer. The outcome would be at its best quality at this specific allocation, which was carbon content 1.5 wt% and copper content at 15 wt%. We could find graphene signal through Raman analysis at 1.5 wt% carbon and 1 wt% copper. Due to the change of isothermal times, the mechanism of graphite layer growth could be deduced. The variation of growth steps could influence graphite layer’s wrinkle level and its appearance. Under this content of carbon and copper (1.5C-Fe58.45Ni25.05Cu15), which etched by nitric acid, could separate into a large-area graphite layer from Fe-Ni-Cu alloy. The graphite layer sample would be a beneficial usage to future development.
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Lin, Shyh-Yuh, and 林世煜. "Toughness Behavior of Zirconia in B2 Ni-Al-Fe Intermetallic Alloy." Thesis, 1997. http://ndltd.ncl.edu.tw/handle/48845073856523997605.
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碩士國立台灣工業技術學院
機械工程技術研究所
85
NiAl鎳鋁介金屬化合物是一種具有優良高溫特性之結構性材 料 ，它具有高熔點、低密度、良好的高溫強度及抗氧化能力是 極具潛力的 航空工業材料，但是一般介金屬化合物的缺點─常 溫脆性不良、破壞韌 性與加工製造性較一般金屬差，卻限制了 NiAl之發展。而這些缺點根據 過去文獻研究有部份是由於NiAl 常溫下之不良滑移系統{110}<001>所造 成，但是具有相同結 構之FeAl介金屬化合物其卻以{110}<111>之滑移系 統變形而 展現出延性。有研究即在NiAl中加入Fe形成Ni-Al-Fe三元介 金屬合金，其結果雖對於NiAl常溫脆性有部份改善但效果仍不 顯著。而 ZrO2是結構性的陶瓷材料，其特殊的應力誘發相轉換 韌化作用使其在韌 化一般的脆性陶瓷材料之應用上扮演著重要 角色。本研究即著眼在以 Ni-Al-Fe介金屬合金為基底而ZrO2 為強化相形成介金屬基複合材料( IMCs)，藉ZrO2之應力誘發相 轉換韌化之作用提供另一韌化機構來加強 Ni-Al-Fe介金屬合 金之韌化作用，並探討此介金屬基複合材料之韌化行 為。 本研究中試片係採用99.5 %之純NiAl粉末、99.9 %之純Fe粉 末與含5.4 wt% Y2O3之ZrO2粉末均勻混合後、再於氬氣氛下以 電弧熔煉 方式製作試片。經分析Ni-Al-Fe介金屬合金添加ZrO2 陶瓷之介金屬基- 陶瓷複合材料之韌性行為可得下列結果： (1)ZrO2成分於Ni-Al-Fe介金 屬基底中係以網狀結構方式存在，且 在兩者界面上亦有特定之方位 關係。 (2)經鑽石壓痕硬度測試後於Ni-Al-Fe介金屬基底中之ZrO2成分 之? 眼劃c造由正方相轉變成單斜相。 (3)經鑽石壓痕硬度測試後 ZrO2網狀結構區產生表面起伏痕跡與雙晶之現象。 (4)於Ni-Al-Fe介金 屬合金中添加ZrO2可提高其硬度。 (5)ZrO2網狀結構提供了塑性變形區 可抵消外加應力並限制裂縫之延 伸。 由上述結果可知ZrO2 網狀結構具有改善Ni-Al-Fe介金屬合金脆性之 效果。 The nickel aluminide, NiAl has a B2 structure, exhibits a high melting temperature, good thermal conductivity, low density and high resistance to oxidation. Those unique properties make it a potential candidate material in structure application at elevated temperature. The lack of ductility at lower temperature has been one of the barriers limiting the use of NiAl alloy. In several earlier investigations on NiAl, it has been known that the poor duc-tility is partly due to the deformation via {110}<001> slip at low tempera-ture, which provides only three independent slip system, insufficient for generalized plastic flow. In recent years, many research programs have focused on inducing additional slip systems through macroalloying techniques. FeAl also has the B2 structure but deforms by <111> slip at room temperature and displays some tensile ductility. Thus, the ternary additions of iron to NiAl can promote <111> slip and improve ductility. But the Ni-Al-Fe ternary alloy still exhibits brittle intergranular fracture at room temperature. Zirconia (ZrO2) is well known to be a transformation toughening,involving the tetragonal to monoclinic phase change. The study consider to add partially stabilized Zirconia (PSZ)in Ni-Al-Fe ternary alloy to provide another tougheningmechanism. The alloys used in this investigation were prepared using 99.5 %pure NiAl powder, 99.9 % pure Fe powder and ZrO2 (contain 5.4 wt % Y2O3) powder by are melting in a argon atmosphere. A detailed investigation and analysis of toughness behavior of Ni-Al-Fe intermetallic alloy + ZrO2 ceramic composite at room temperature revealed that: 1.The compositions of ZrO2 formed network structure in Ni-Al-Fe matrix and there were specific orientationrelationship on the boundary. 2.After diamond pyramid indentation testing the crystal structure of ZrO2 in Ni-Al-Fe matrix was transformed into Monoclinic structure. 3.There were surface relief and microtwining in ZrO2 network structure after diamond pyramid indentation testing. 4.Adding ZrO2 into Ni-Al-Fe intermetallic alloy can rise its hardness. 5.The ZrO2 network structure provided the plastic region to offset the external stress and restrict the propagation of cracks. Finally, it is concluded that the ZrO2 ,which form network structure, can improve the toughness of Ni-Al-Fe intermet-allic alloy.