Готові списки джерел за темами / Cobalt-based Superalloy

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Автор: Grafiati

Опубліковано: 6 вересня 2023

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Статті в журналах з теми "Cobalt-based Superalloy"

Ruzuqi, Rezza, Drs Djony Izak Rudyardjo, M.Si., and Andi Hamim Zaidan, S.Si., M.Si., Ph.D. "Synthesis and Characterization of Nickel-Based Superalloy Materials for Manufacturing Aircraft Turbine Blades." Indonesian Applied Physics Letters 2, no. 2 (December 2, 2021): 49. http://dx.doi.org/10.20473/iapl.v2i2.31557.

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The research has been conducted to manufacture nickel-based Superalloy materials. The purpose of this research was to find out the effects of variation of nickel composition on physical and mechanical properties of the Superalloy materials and find out the appropriate composition of Superalloy materials as materials for turbine blades. This research used nickel, cobalt, chromium, molybdenum, aluminium, and titanium commercial. The results showed that with more addition of nickel composition, the density and hardness values increased. This research showed that nickel-based Superalloy material 59 wt% was better applied as materials for turbine blades. It is also supported by the results of the test microstructure, where the structure of the sample morphology is more delicate and denser and contains smaller pores. Based on the XRD test results are also shown in the sample has been formed Superalloys phase.

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Jonšta, Petr, Irena Vlčková, Zdenĕk Jonšta, and Mariusz Król. "Material Analysis of the Extended-Life Cobalt-Based Superalloys Used in the Manufacturing of Glass Tools." Solid State Phenomena 270 (November 2017): 21–26. http://dx.doi.org/10.4028/www.scientific.net/ssp.270.21.

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Cobalt-based superalloys are among the most important materials for application in the demanding conditions of the glass industry. These superalloys with extended life are due to their excellent heat-resistant properties an important part of glass tools, especially of spinning discs. In the submitted paper, a material analysis of the commercially produced cast cobalt superalloy for spinning discs, including metallographic analysis supplemented by an electron X-ray analysis of minority phases, is carried out. An assessment of harmful gases, in particular oxygen and nitrogen, has also been carried out. They appear to be the cause of defects that often lead to the subsequent degradation of the material.

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Chen, Tao-Hsing. "THE MECHANICAL BEHAVIOUR OF COBALT SUPERALLOYS WITH TI ELEMENT ADDITION." Transactions of the Canadian Society for Mechanical Engineering 37, no. 3 (September 2013): 365–73. http://dx.doi.org/10.1139/tcsme-2013-0026.

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The influence of titanium element, strain rate and tested temperatures on the mechanical properties and microstructural characteristics will be investigated in this paper. These cobalt-based superalloys are tested using material testing system (MTS) at strain rates of 10−3, 10−2 and 10−1 s−1 and at temperatures of 700, 500 and 25° C, respectively. It is found that the flow stress increases with increasing strain rate and Ti, but decreases with increasing temperature. Furthermore, the strain rate sensitivity increases with increasing strain rate, but decreases with increasing temperature. The microstructural observations confirm that the mechanical response of the cobalt superalloy specimens is directly related to the effects of the titanium contents, strain rate and temperature on the evolution of the microstructure. It can be observed that the strengthening effect in cobalt-based superalloys is a result primarily of dislocation multiplication. The dislocation density increases with increasing strain rate, but decreases with increasing temperature.

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Cep, Robert, Adam Janasek, Jana Petru, Lenka Cepova, Andrej Czan, and Jan Valicek. "Hard Machinable Machining of Cobalt-based Superalloy." Manufacturing Technology 13, no. 2 (June 1, 2013): 142–47. http://dx.doi.org/10.21062/ujep/x.2013/a/1213-2489/mt/13/2/142.

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Lee, J. S., Je Hyun Lee, Baig Gyu Choi, Chang Yong Jo, Ung Yu Paik, and S. G. Gang. "The Solidification Microstructure and Carbide Formation Behaviors in the Cobalt-Based Superalloy ECY768." Materials Science Forum 486-487 (June 2005): 374–77. http://dx.doi.org/10.4028/www.scientific.net/msf.486-487.374.

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Co-base superalloys have been applied in the stationary compoents of gas turbine owing to their excellent high temperaure properties. The stationary Co-base alloy components are generally manufactured by casting. Solidification behavior of the alloy is an important factor in the selection of casting parameters. In the present study, solidification microstructure and carbide formation behaviors were studied by directional solidification. Directional solidification experiments were carried out at the solidification rates of 0.5 ~ 150µm/s with the Co-base superalloy ECY768. Between the dendrites just below the final freezing temperature, MC carbide and M23C6 carbide were found. It was identified that the script or blocky carbides were Ta or W-rich MC carbide, and the lamellar carbides were Cr-rich M23C6 eutectic carbides. The solid/liquid interface morphology clearly showed that freezing of the Cr-rich eutectic carbide occurred just after the script type MC carbide.

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Tsai, Jong-Cheng, and Jing-Bang Duh. "Hot working behaviors of cast cobalt-based superalloy." Scripta Metallurgica et Materialia 27, no. 5 (September 1992): 561–64. http://dx.doi.org/10.1016/0956-716x(92)90340-k.

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NANBU, Youhei, Kazuhiro OCHIAI, Daisuke AKIBA, Teruaki NAGAKUBO, and Shinichi MATSUDA. "High-Aspect-Ratio Microdrilling of Cobalt-Based Superalloy." Journal of the Japan Society for Precision Engineering 75, no. 9 (2009): 1083–87. http://dx.doi.org/10.2493/jjspe.75.1083.

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Niki, Takahiro, Kazuhiro Ogawa, and Tetsuo Shoji. "Segregation of Alloying Elements of Directionally Solidified Nickel Based Superalloy CM247LC during Creep Degradation Process." Key Engineering Materials 353-358 (September 2007): 537–40. http://dx.doi.org/10.4028/www.scientific.net/kem.353-358.537.

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The mechanism of the degradation process of nickel based superalloy CM247LC under creep loading was analyzed by considering the microscopic chemical composition of the material such as phase boundary of γ and γ’ phases. In this study, a Directionally Solidified (DS) nickel-based superalloys CM247LC was used as test specimens. The creep test was performed at 900oC under an uni-axial stress of 216 MPa. Each specimen was creep ruptured and interrupted at different hours and then analyzed. The change of chemical composition around the interface analyzed precisely by used Auger Electron Spectroscopy (AES). It was found that the local enrichment or lack of cobalt and chromium was found at the interface. This tendency was not found in the stress free area. Since chromium is the well-known element that dominates the degradation of this material, such an enrichment or lack of cobalt and chromium may play an important role for forming a crack propagation path near the interface. This local segregation should be analyzed further to make clear degradation mechanism of this material.

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Zielinska, M., and J. Sieniawski. "Surface Modification and its Influence on the Microstructure and Creep Resistance of Nickel Based Superalloy René 77 / Modyfikacja Powierzchniowa Oraz Jej Wpływ Na Mikrostrukture I Wytrzymałosc Na Pełzanie Odlewów Z Nadstopu Niklu Ren´E 77." Archives of Metallurgy and Materials 58, no. 1 (March 1, 2013): 95–98. http://dx.doi.org/10.2478/v10172-012-0157-6.

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Superalloy René 77 is very wide used for turbine blades, turbine disks of aircraft engines which work up to 1050°C. These elements are generally produced by the investment casting method. Turbine blades produced by conventional precision casting methods have coarse and inhomogeneous grain structure. Such a material often does not fulfil basic requirements, which concern mechanical properties for the stuff used in aeronautical engineering. The incorporation of controlled grain size improved mechanical properties. This control of grain size in the casting operation was accomplished by the control of processing parameters such as casting temperature, mould preheating temperature, and the use of grain nucleates in the face of the mould. For nickel and cobalt based superalloys, it was found that cobalt aluminate (CoAl2O4) has the best nucleating effect. The objective of this work was to determine the influence of the inoculant’s content (cobalt aluminate) in the surface layer of the ceramic mould on the microstructure and mechanical properties at high temperature of nickel based superalloy René 77. For this purpose, the ceramic moulds were made with different concentration of cobalt aluminate in the primary slurry was from 0 to 10% mass. in zirconium flour. Stepped and cylindrical samples were casted for microstructure and mechanical examinations. The average grain size of the matrix ( phase), was determined on the stepped samples. The influence of surface modification on the grain size of up to section thickness was considered. The microstructure investigations with the use of light microscopy and scanning electron microscopy (SEM) enable to examine the influence of the surface modification on the morphology of ’ phase and carbides precipitations. Verification of the influence of CoAl2O4 on the mechanical properties of castings were investigated on the basis of results obtained form creep tests.

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Lei, Yan, Chenglin Li, and Liang Wan. "High-Temperature Tensile Properties of a Cobalt-Based Co-20Cr-15W-10Ni Superalloy with a Bimodal Grain Structure." Crystals 13, no. 2 (January 29, 2023): 232. http://dx.doi.org/10.3390/cryst13020232.

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Cobalt-based superalloys are common materials for the manufacturing of various components used in aerospace applications. Conventional cobalt-based superalloys with a unimodal grain structure generally exhibit low strength and ductility at high temperatures. A bimodal grain structure of a cobalt-based superalloy, Co–20Cr–15W–10Ni (CCWN), was designed to achieve both high strength and ductility at high temperatures. The deformation behavior and tensile properties of a CCWN alloy with unimodal fine-grain (FG), coarse-grain (CG), and bimodal (FG/CG) structures were investigated at 900 °C. The microstructures and substructures after high-temperature deformation were examined via electron backscatter diffraction (EBSD) and electron channeling contrast imaging (ECCI) to determine the deformation mechanisms. The microstructural observation showed that the bimodal grain structure consisted of FG and CG domains. During high-temperature deformation at 900 °C, the FG structure was mainly deformed by dynamic recrystallization (DRX), maintaining a similar FG structure. The CG structure was mainly deformed by DRV, resulting in a small amount of DRX grains and a large amount of dynamic recovery (DRV) grains. However, the bimodal grain structures were mainly softened via DRX and transformed into a new bimodal structure, ultrafine grain (UFG) and FG. The FG domains tended to deform via dislocations, and the CG domains via twinning. The high-temperature tensile tests revealed that the bimodal-structured alloy exhibited both higher strength and ductility than those of the alloy samples with unimodal FG or CG structure. This is associated with the newly developed UFG/FG structures in the bimodal grain-structured samples during high-temperature deformation. This work may provide new insight into the development of high-temperature alloys with bimodal grain structures.

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Більше джерел

Дисертації з теми "Cobalt-based Superalloy"

Léglise, Mélissa. "Amélioration des propriétés mécaniques et chimiques de superalliages base nickel et base cobalt de fonderie utilisés pour le fibrage du verre fondu à 1000°C - 1100°C." Thesis, Université de Lorraine, 2018. http://www.theses.fr/2018LORR0228.

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Les assiettes de fibrage utilisées pour la production de fibres de verre subissent d’importantes contraintes mécaniques, chimiques et thermiques. Par conséquent, cette pièce se dégrade et doit être périodiquement remplacée. Le but de ces travaux est d’augmenter la durée de vie des assiettes de fibrage en améliorant les propriétés mécaniques et chimiques des superalliages qui les constituent. Plus précisément, l’objectif de cette thèse est, dans un premier temps, d’améliorer les alliages utilisés pour le fibrage à 1000°C, puis dans un second temps, de trouver un superalliage pouvant fibrer à 1125°C. Ces travaux ont été menés sur deux familles de superalliages : base nickel et base cobalt. Les propriétés chimiques ont été caractérisées par des essais thermogravimétriques et les propriétés mécaniques par des essais de fluage flexion 3 points. Pour l’alliage base Ni, l’influence des éléments minoritaires subis, Mn et Si, a été étudiée. Les propriétés mécaniques de cet alliage ont fait, ensuite, l’objet d’essais d’amélioration par l’addition de titane, zirconium, tantale, hafnium et de niobium. L’addition d’aluminium a été aussi expérimentée mais ayant pour but d’améliorer les propriétés chimiques de l’alliage. Enfin, des études ont été aussi menées sur l’addition de métaux nobles (Pd et Ru) et de terres rares (Y, La et Ce). Concernant les superalliages base cobalt, l’étude s’est portée sur un alliage base Co qui a antérieurement montré de bonnes propriétés générales pour une utilisation à 1125°C et non à 1000°C. Des variantes avec une teneur abaissée en tantale, sans hafnium et sans tungstène ont été étudiées. Pour clore ces travaux, l’augmentation de la teneur en nickel et un traitement thermique ont été étudiés afin d’améliorer la résistance à l’oxydation de ce second alliage
The fiberizing spinners used to produce the glass fibers undergo sizable mechanical, chemical and thermal solicitations. Therefore, this piece is degraded and must be periodically replaced. The purpose of these works is to increase the lifetime of the fiberizing spinners by improving the mechanical and chemical properties of the superalloys that constitute them. More precisely, the objective of this thesis is, in the first time, to improve the alloys used to fiberize at 1000°C, and in a second time, to find a superalloy that can fiberize at 1125°C. These works are focused on two families of superalloys: nickel-based and cobalt-based. The chemical properties are characterized by the thermogravimetry tests and the mechanical properties by 3 points flexural creep tests. For the Ni-based alloy, the influences of unwanted minority elements, Mn and Si, were studied. The mechanical properties of this alloy are subject to improvement tests by the addition titanium, zirconium, tantalum, hafnium and niobium. The aluminium addition was also experimented but with the aim of improving the chemical properties of the alloy. Finally, the studies were also driven on the addition of noble metals (Pd and Ru) and of rare earths (Y, La and Ce). Concerning the cobalt-based superalloys, the study focused on an alloy which has previously shown good general properties to be used at 1125°C and no at 1000°C. The versius with a lowered content in tantalum, without tungsten and without hafnium were studied. To close this work, the increase of nickel and a heat treatment were studied in order to improve the oxidation resistance of this second alloy

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Ur-Rehman, Hamad [Verfasser], Mathias [Gutachter] Göken, and Uwe [Gutachter] Glatzel. "Solid Solution Strengthening and Diffusion in Nickel- and Cobalt-based Superalloys / Hamad Ur-Rehman. Gutachter: Mathias Göken ; Uwe Glatzel." Erlangen : FAU University Press, 2016. http://d-nb.info/1112737502/34.

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[Verfasser], Hamad ur Rehman, Mathias [Gutachter] Göken, and Uwe [Gutachter] Glatzel. "Solid Solution Strengthening and Diffusion in Nickel- and Cobalt-based Superalloys / Hamad Ur-Rehman. Gutachter: Mathias Göken ; Uwe Glatzel." Erlangen : FAU University Press, 2016. http://nbn-resolving.de/urn:nbn:de:bvb:29-opus4-74073.

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Salgado, Marcus Vinicius da Silva. "Processamento e caracterização de ligas do sistema Co-Ni-Al-W-Cr-(Nb,Ta)-C-B visando aplicação como material de ferramenta para soldagem por atrito." Universidade de São Paulo, 2015. http://www.teses.usp.br/teses/disponiveis/97/97134/tde-03122015-155841/.

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Os objetivos deste trabalho foram processar e caracterizar microestrutural e mecanicamente superligas à base de cobalto do sistema Co-Al-W-Ni-Cr-(Nb,Ta)- C-B com microestrutura ?/?\'. Visando possível aplicação em ferramenta para Soldagem por Atrito com Pino Não Consumível (SAPNC), em inglês Friction Stir Welding (FSW) nas composições: (Co-10Al-7,5W-30Ni-10Cr-3,0Nb-0,6C-0,06B %at. ) - 30Ni-3Nb, (Co-10Al-7,5W-40Ni-10Cr-3,0Nb-0,6C-0,06B %at.) - 40Ni-3Nb, (Co-10Al-7,5W-50Ni-10Cr-3,0Nb-0,6C-0,06B %at.) - 50Ni-3Nb além da liga patenteada (Co-10Al-7,5W-40Ni-10Cr-3,0Ta-0,6C-0,06B %at.) - 40Ni-3Ta considerada padrão para este projeto. A caraterização microestrutural foi feita por microscopia eletrônica de varredura (MEV), microscopia eletrônica de varredura por emissão de campo (MEV-FEG), medidas de microanálise semi-quantitativa e mapeamento químico por EDS, caracterização por difração de raios X, além do ensaio mecânico de dureza Vickers em todas as amostras. Os resultados da caracterização microestrutural e mecânica para a liga 40Ni-3Ta mostraram-se semelhantes aos encontrados na literatura enquanto que a composição 40Ni-3Nb foi a que apresentou resultados mais próximos em relação à liga padrão.
The objectives of this study were to process and characterize microstructural and mechanical cobalt-based superalloys from Co-Al-W-Ni-Cr-(Nb,Ta)-C-B system with ?/? \' microstructure. Aiming possible application for Friction Stir Welding (FSW) tool in the compositions: (Co-10Al-7.5W-30Ni-10Cr-3.0Nb-0.6C-0.06B %at.) - 30Ni-3Nb, (Co-10Al-7.5W-40Ni-10Cr-3.0Nb-0.6C-0.06B %at. ) - 40Ni-3Nb, (Co-10Al-7.5W-50Ni-10Cr-3.0Nb-0.6C-0.06B %at.) - 50Ni-3Nb, including the patented alloy (Co-10Al-7.5W -40Ni-10Cr-3.0Ta-0.6C-0.06B %at.) - 40Ni-3Ta considered the standard alloy for this project. The microstructural characterization was made by Scanning Electron Microscopy (SEM), Scanning Electron Microscopy with Field Emission Gun (SEM-FEG), semi-quantitative microanalysis measures and chemical mapping by EDS, characterization by X - ray diffraction and mechanical test of hardness Vickers in all the samples. The results of the microstructural and mechanical characterization for 40Ni-3Ta alloy were similar to those found in the literature. The 40Ni-3Nb alloy showed the closest results, among the other alloys studied in comparison with the standard alloy.

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Li, Han-yun, and 黎瀚揚. "Corrosion Behavior and Electrochemical Properties of Commercial Cobalt-based Superalloy." Thesis, 2011. http://ndltd.ncl.edu.tw/handle/23354580752903028757.

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碩士
中國文化大學
材料科學與奈米科技研究所
99
This research made use of different chlorine concentrations and temperatures to explain the commercial cobalt-based super-alloys electrochemical properties and corrosion behavior of the commercial cobalt-based super-alloys in terms of the electrochemical polarization curves. Both SEM and the immersion experiments were used to explain the micro-structure and to understand the effect of temperature and concentration on the pit size. Several different solutions and concentrations were also applied to confer the critical pitting temperature (CPT) of the cobalt-based super-alloys. In three different chloride salts, the corrosion potential (Ecorr) are of little change of temperature and concentration, and the pitting potential (Eb) gradually decreased as temperature increases. Among them, Fecl3 is a rather special case in which the difference between Ecorr and Eb in potential are relatively small which implies the alloy immediately pitted right after the specimen being scanned beyond the Ecorr. The corrosion morphology of the alloy tested in three kinds of chloride solutions at 80oC observed by SEM shows that the corrosion all initiated preferentially at the interdendritic regions which were eventually merged into larger area as time goes on; the damage were particularly pronounced for Fecl3 than the other two.

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Benson, Michael Lee. "Strain-Induced Phase Transformation and Anisotropic Lattice-Strain Development in a Cobalt-Based Superalloy." 2008. http://trace.tennessee.edu/utk_graddiss/327.

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This dissertation addresses two issues concerning the deformation behavior of a cobalt-based superalloy: 1) the strain-induced face-centered-cubic to hexagonal-closepacked phase transformation and 2) the anisotropic lattice-strain development. Cobaltbased alloys are known to exhibit a metastable face-centered-cubic crystal structure at room temperature. This structure can transform to the thermodynamically-stable hexagonal-close-packed phase upon application of a load. While this phenomenon has been studied and documented before, this work offers a more in-depth study on this issue, as it addresses the phase transformation under several loading modes: monotonic tension, monotonic compression, stress-controlled high-cycle fatigue, and strain-controlled lowcycle fatigue. The experimental technique utilized in this research is neutron diffraction. This nondestructive method is particularly well suited to the problem because it can be used to study the transformation with the mechanical load applied in-situ. Anisotropic lattice strain development is a natural problem to study, as neutron diffraction is also well suited for this measurement. Individual crystallites in a polycrystalline matrix by nature have directionally-dependent responses to the applied stress. When neighboring anisotropic grains interact, inhomogeneities known as intergranular strains develop. This dissertation assumes that the total lattice strain is the sum of two contributions: the linear-elastic contribution and the plasticity-induced intergranular contribution. Within the context of this analysis, the effect of the phase transformation on the deformation behavior is also inferred.

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Sharma, Abhishek. "An Evaluation of the Mechanical Behavior of some new High Temperature Materials." Thesis, 2018. https://etd.iisc.ac.in/handle/2005/5254.

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Two new high-temperature alloy systems have been discovered recently at the Indian Institute of Science, which form the basis of this thesis. The first alloy system is an Intermetallic-Intermetallic eutectic composite alloy in the nickel-rich end of the Ni-Al- Zr ternary system, first reported by Tiwary et al. These eutectic composites have very impressive room temperature yield strengths of about 2 GPa which are retained till about 700 . Coupled with 2 to 5% tensile plasticity at room temperature, excellent high-temperature oxidation resistance, good long-term microstructural stability and very low densities of about 7.35–7.95 gm/cm3, these materials are exciting candidates for high-temperature applications. The second alloy system comprises of Tungsten free Cobalt based superalloys having the classical − 0 microstructure similar to that of nickel-based superalloys as described by Makineni et al. The presence of the L12 phase in cobalt-based systems was reported by Lee et al. and Sato et al. where the addition of 25 wt.% tungsten seemed to stabilize the metastable Co3Al. This however pushed the density of the alloy to about 9–10 gm/cm3, making it too heavy for most high-temperature applications. A large body of work followed trying to reduce or eliminate the presence of tungsten in these alloys. The new alloys by Makineni et al. do not contain tungsten which reduces the density to about 8.0–8.4 gm/cm3. The high-temperature mechanical behavior of some of the alloys from these two sysi tems has been evaluated in the current thesis. This thesis is divided into six chapters.

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Ko, Chih-Chien, and 柯志建. "The Effects of Vacuum Sintering and Heat Treatments on the Microstructure and Mechanical Properties of Cobalt Based Superalloy after TiC Particles Dispersion Strengthening." Thesis, 2011. http://ndltd.ncl.edu.tw/handle/65s9x7.

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碩士
國立臺北科技大學
材料及資源工程系研究所
99
Cobalt-based superalloys are used extensively in applications requiring good wear resistance, corrosion resistance and heat resistance. Many of the properties of these alloys arise from the crystallographic nature of cobalt, the solid solution strengthening and carbide precipitation effects of chromium, tungsten and molybdenum. Metal matrix composites are known to exhibit exceptional wear resistance; therefore, several investigators have used titanium carbide (TiC) as a reinforcing medium in a ferrous metal matrix in order to enhance this property. TiC has proved its suitability in Fe or Fe-based alloys due its high hardness, low density and chemical stability with Fe-based alloys. In this study, we have mixed and added different amounts of TiC powders (10, 15 and 20 wt %) to the Cobalt-based superalloy powders. The mixing processed was finished by ball milling and granulation in a laboratory. In addition, the mixing powders (Cobalt-based superalloy and TiC) were sintered at 1260, 1270, 1280 and 1290°C, and then a series of HIP processes and heat treatments were performed. Meanwhile, the parameter of HIP treatment was 1250°C, 125 MPa and 100 min. The heat treatment processes were heating to 1100°C and maintaining for 40 min for quenching; aging at 760°C and soaking time was 6, 9, 12 h, respectively. Various materials characterization techniques were used to evaluate the materials’ properties and microstructures, including: apparent porosity, hardness test, transverse rupture strength (TRS) test, OM, and SEM microstructral examinations. The experimental results show that the highest TRS value of 1566.7 MPa was obtained by the 15 wt% TiC additive powder, which was sintered at 1280°C and then followed by HIP process and solid solution heat treatment. It also has been proved that the closed pores can be effectively eliminated (1.2% → 0.86%) by HIP treatment; in addition, the M6C carbides can produce more uniform precipitation on the grain-boundary and matrix after heat treatment. Furthermore, the highest hardness value of HRA 80.4 was obtained by the 20 wt% TiC additive powder, which was only sintered at 1290°C.

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Makineni, Surendra Kumar. "Improvement of High Temperature Strength of Al and Co Alloy by L12 Type Coherent Precipitates." Thesis, 2015. https://etd.iisc.ac.in/handle/2005/4348.

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The present work aims at developing a new class of high temperature alloys based on ordered intermetallic compound that forms coherently with the matrix during solid state transformation. The chosen intermetallics have L12 ordered structure, which is a derivative of fcc unit cell. Most popular example of this fcc derivative is Ni3Al that is critical in developing high strength at high temperatures (~900°C) in commercially successful Ni based superalloys. Similar ordered structures form either in stable or metastable form can act as a main strengthening constituent in Al and Co matrices. For example Al3Sc, Al3Zr, Al3Hf can be dispersed in fcc Al matrix that are stable at temperatures ~ 400°C due to very low diffusivity of transition metals (Sc, Zr, Hf etc.) in the matrix. However, due to low solid solubility of these transition metals, the obtained volume fraction of these precipitates in the matrix is not sufficient to provide adequate room temperature strength. In fcc Co matrix, stable Co3Ti phase with L12 ordered structure forms with cuboidal morphology. However, besides having lower melting point, the precipitates have large misfit that lowers thermal stability at high temperatures. Recently, addition of Al and W with a proper ratio in Co is reported to lead the formation of metastable Co3(Al,W) L12 ordered phase in fcc α-Co matrix. This provides significant strength at high temperatures (~ 900°C). The main drawback for these alloys is their high densities (9.6 to 10.5 gm.cm-3) due to the requirement of compulsory addition of W (~ 15 to 25 wt%) for stabilising the ordered phase. In the present work, these problems are overcome leading to the development of new class of Al and Co alloys. The thesis is organized in three parts. In the first part, the principles of strengthening that can be optimized to develop newer high temperature high strength alloys are reviewed. The ordered L12 structure, which is the mainstay of the current effort of new alloy development, is elaborated. In the second part we present the results of our effort to the development a new class of high strength high temperature Al alloys. A new approach has been adopted to get a microstructure that contains both high temperature stable and room temperature strengthening precipitates. This has been illustrated by two Al rich compositions, Al-2Cu-0.1Nb-0.15Zr and Al-2Cu-0.1Hf-0.15Zr (at% unless stated otherwise). Addition of Nb/Zr or Hf/Zr in Al alloys leads to the formation of high temperature stable L12 ordered spherical coherent precipitates in the fcc Al matrix. Cu addition gives room temperature strengthening θ’ and θ” precipitates. The arc melted alloys were chill cast (suction cast) in the form of 3 mm rods followed by a novel three stage heat treatment process, as shown below. In the case of Al-2Cu-0.1Nb-0.15Zr alloy, the chill cast structure consists of Cu rich phase at the boundaries along the α-Al dendrites while Zr and Nb partition inside the α-Al dendrites. Aging at 400°C leads to an increase in the hardness of the cast alloy due to the precipitation of coherent L12 ordered Al3(Zr,Nb) spherical precipitates (~5nm) in the α-Al dendrites. Zr strongly partitions to the L12 ordered precipitate relative to the matrix. Nb exhibits weak partitioning in the precipitate. Further solutionising was optimized at 535°C for 30 minutes such that the segregation of Cu in the chill cast samples can be eliminated. The WDS mapping shows that Cu dissolved uniformly in the α-matrix while the Zr/Nb enriched α-Al dendrites are still present. The L12 ordered precipitates are mostly found in these Zr/Nb enriched dendrites formed during solidification. The precipitates sizes are finer (~5 nm) in dendrites and larger in the interdendritic region. The Nb partitioning increases in the ordered L12 precipitates relative to the matrix after solutionising. On aging at 190°C, fine θ” precipitates nucleate on prior Al3(Zr,Nb) precipitates present in α-Al dendrites while the interdendritic regions contain coarser θ’ nucleated on larger size L12 precipitates. The θ”/θ’ are much finer and higher in number density for the quaternary alloy compared to binary Al-2Cu alloy subjected to conventional heat treatment. The quaternary alloy show higher peak hardness of 1500 ± 8 MPa after 5 hours of aging at 190°C compared to binary Al-2Cu alloy with peak hardness of 1260 ± 11 MPa.

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Частини книг з теми "Cobalt-based Superalloy"

Jithesh, K., M. Arivarasu, and M. Nageswara Rao. "Studies on Oxidation Behaviour of Cobalt-Based Superalloy 605." In Lecture Notes in Mechanical Engineering, 155–63. Singapore: Springer Singapore, 2021. http://dx.doi.org/10.1007/978-981-16-0909-1_16.

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Benson, Michael L., A. D. Stoica, Peter K. Liaw, Hahn Choo, T. A. Saleh, X. L. Wang, Donald W. Brown, and Dwaine L. Klarstrom. "Intergranular Strain and Phase Transformation in a Cobalt-Based Superalloy." In Materials Science Forum, 893–98. Stafa: Trans Tech Publications Ltd., 2006. http://dx.doi.org/10.4028/0-87849-414-6.893.

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Andhare, Atul B., K. Kannathasan, and Manoj Funde. "Optimization of Machining Parameters for Turning of Haynes 25 Cobalt-Based Superalloy." In Advances in Mechanical Engineering, 703–10. Singapore: Springer Singapore, 2020. http://dx.doi.org/10.1007/978-981-15-3639-7_84.

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Sarkar, P., S. Narahari Prasad, M. Chatterjee, and M. Narayana Rao. "Influence of Thermomechanical Treatment on Structure and Properties of a Cobalt Based Superalloy." In Ni-Co 2013, 353–56. Cham: Springer International Publishing, 2013. http://dx.doi.org/10.1007/978-3-319-48147-0_27.

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Sarkar, P., S. Narahari Prasad, M. Chatterjee, and M. Narayana Rao. "Influence of Thermomechanical Treatment on Structure and Properties of a Cobalt Based Superalloy." In Ni-Co 2013, 353–56. Hoboken, NJ, USA: John Wiley & Sons, Inc., 2013. http://dx.doi.org/10.1002/9781118658826.ch27.

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Lee, J. S., Je Hyun Lee, Baig Gyu Choi, Chang Yong Jo, Un Gyu Paik, and S. G. Gang. "The Solidification Microstructure and Carbide Formation Behaviors in the Cobalt-Based Superalloy ECY768." In Materials Science Forum, 374–77. Stafa: Trans Tech Publications Ltd., 2005. http://dx.doi.org/10.4028/0-87849-966-0.374.

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Byeon, Jai Won, C. S. Kim, Y. H. Kim, S. I. Kwun, and S. J. Hong. "Assessment of Surface Damage in Thermally Aged FSX414 Cobalt-Based Superalloy Using Ultrasonic Rayleigh Wave." In Materials Science Forum, 651–54. Stafa: Trans Tech Publications Ltd., 2005. http://dx.doi.org/10.4028/0-87849-960-1.651.

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Chen, L. J., P. K. Liaw, Y. H. He, M. L. Benson, J. W. Blust, P. F. Browning, R. R. Seeley, and D. L. Klarstrom. "Influence of Hold Time and Temperature on Low-Cycle Fatigue Behavior of Cobalt-Based Superalloy Haynesr̀ 188." In Fatigue and Fracture Behavior of High Temperature Materials, 84–93. Hoboken, NJ, USA: John Wiley & Sons, Inc., 2013. http://dx.doi.org/10.1002/9781118787823.ch11.

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Stewart, C. A., R. K. Rhein, A. Suzuki, T. M. Pollock, and C. G. Levi. "Oxide Scale Formation in Novel γ-γ′ Cobalt-Based Alloys." In Superalloys 2016, 991–99. Hoboken, NJ, USA: John Wiley & Sons, Inc., 2016. http://dx.doi.org/10.1002/9781119075646.ch105.

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Kvapilova, Marie, Petr Kral, Jiri Dvorak, and Vaclav Sklenicka. "Creep Fracture Ductility of Cobalt-Based Superalloys." In Structural Integrity, 184–89. Cham: Springer International Publishing, 2018. http://dx.doi.org/10.1007/978-3-319-91989-8_41.

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Тези доповідей конференцій з теми "Cobalt-based Superalloy"

Waldorf, Daniel, Scott Liu, Michael Stender, and Daniel Norgan. "Alternative Binder Carbide Tools for Machining Superalloys." In ASME 2008 International Manufacturing Science and Engineering Conference collocated with the 3rd JSME/ASME International Conference on Materials and Processing. ASMEDC, 2008. http://dx.doi.org/10.1115/msec_icmp2008-72369.

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This study examines the performance of a new class of wear-resistant but economical cutting tools produced by varying the binder composition of standard cemented carbide composites. By replacing some or all of the cobalt binder with rhenium and nickel-based superalloy, a stronger composite tool results, potentially capable of machining heat-resistant superalloys at significantly higher cutting speeds. Sample tools with alternative binder were produced and compared to standard tools bound with cobalt only. Turning experiments on Inconel 718 were run to evaluate wear resistance and tool life for several grades. The experimentation also examined the effects of varying the relative proportions of each binder constituent as well as the overall binder percentage in the composite. Results show a clear advantage of the alternative binder tools as evidenced by a 150% increase in tool life or the equivalent of an 18% increase in cutting speed. Although increasing amounts of rhenium in the binder show a positive effect on performance, the effects of superalloy and overall binder % are inconclusive.

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Greaves, Wayne, and Hans van Esch. "High Temperature Brazing for Cobalt-Based Gas Turbine Components." In ASME Turbo Expo 2000: Power for Land, Sea, and Air. American Society of Mechanical Engineers, 2000. http://dx.doi.org/10.1115/2000-gt-0337.

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A unique high temperature brazing process was developed for crack repair and surface restoration of cobalt superalloy components of industrial gas turbines. The repair method begins with a special cleaning operation consisting of both chemical and ultrahigh vacuum processes. A new high-temperature braze material, with a composition compatible with most of the common cobalt-based turbine alloys, was developed. The mechanical properties and weldability of the brazed material are comparable with those base alloys. Microstructural evaluation and mechanical testing confirmed the desired properties. Also, actual refurbishment applications of General Electric, Westinghouse, and ABB gas turbine components are shown.

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Kramer, D. P., J. R. McDougal, J. D. Ruhkamp, D. C. McNeil, F. A. Koehler, R. A. Booher, and E. I. Howell. "Application of the cobalt based superalloy Haynes Alloy 25 (L605) in the fabrication of future radioisotope power systems." In Space technology and applications international forum - 1998. AIP, 1998. http://dx.doi.org/10.1063/1.54734.

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Azzi, M., L. Vernhes, E. Bousser, and J. E. Klemberg-Sapieha. "Tribo Mechanical Properties of CoCr and NiWCrB Hardfacing Superalloy Coating Systems." In ASME 2014 International Mechanical Engineering Congress and Exposition. American Society of Mechanical Engineers, 2014. http://dx.doi.org/10.1115/imece2014-39372.

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Wear of materials is a serious problem facing industry especially in mechanical applications where moving parts are continuously subjected to friction. Hard coatings prepared by a variety of processes are nowadays considered as effective solutions to protect components against wear. Examples of such processes are: thermal spray coating, vacuum-based coating and hardfacing. In this paper, we study the mechanical, tribological and corrosion properties of two hard coating systems: CoCr Stellite 6 (ST6) hardfacing on 316 stainless steel and NiWCrB Colmonoy 88 (C88) thermal spray coating on Inconel 718. The effect of gas nitriding on the microstructure and wear performance of these coating systems is investigated. X-ray diffraction, energy dispersive spectroscopy and scanning electron microscopy were used for microstructural analysis. Micro-indentation technique was utilized to measure the surface and cross-sectional hardness of the coatings. Rockwell indentation technique was used to evaluate coating adhesion in accordance with CEN/TS 1071-8. Pin-on-disk tests were conducted to assess the tribological performance of the coatings. Microstructural analysis showed that ST6 has a cobalt matrix in the form of dendrites reinforced with metal carbide particles whereas C88 has a Nickel matrix reinforced mainly with metal boride particles. ST6 and C88 improved significantly the wear resistance of their corresponding substrates. This is mainly due to good adhesion and high hardness of the coatings; HR15N values of ST6 and C88 were almost 85 as compared to 61 and 80 for 316 and INC substrates, respectively. ST6 was found to improve significantly the corrosion resistance of 316 whereas C88 decreased the corrosion performance of INC. Moreover, nitriding treatment was found to improve significantly the wear resistance of 316 and INC, however, in the case of ST6, nitriding was beneficial in terms of wear resistance only at relatively low load.

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Levi, C., T. Pollock, R. Rhein, C. Stewart, and A. Suzuki. "Oxide Scale Formation in Novel ?-?' Cobalt-Based Alloys." In Superalloys 2016. The Minerals, Metals & Materials Society, 2016. http://dx.doi.org/10.7449/superalloys/2016/superalloys_2016_991_999.

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Gowreesan, Vamadevan, Wayne Greaves, Yogi Pardhi, and Karen Barrios. "Microstructural Evolution of Wrought and AM Haynes 188 Under Long Term Thermal Exposure." In ASME Turbo Expo 2022: Turbomachinery Technical Conference and Exposition. American Society of Mechanical Engineers, 2022. http://dx.doi.org/10.1115/gt2022-79113.

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Abstract Haynes 188 is a cobalt-based superalloy used in hot section gas turbine components due to its excellent oxidation resistance and elevated temperature stability. Parts made from Haynes 188 are traditionally manufactured from wrought or forged material. Additive manufacturing (AM) may be a less time consuming and more cost-effective alternative, particularly for replacement parts. Additionally, necessary design changes can be quickly introduced into service using additive manufacturing. It is important to understand the effect of long-term thermal exposure on additively manufactured parts before they are put into demanding high temperature applications. Data on the effect of long-term thermal exposure on wrought Haynes 188 is readily available in the open literature. However, such data for additively manufactured Haynes 188 is scarce. This paper discusses an experimental study that investigated the microstructural evolution in wrought and AM Haynes 188 under long-term thermal exposure. Optical metallography and scanning electron microscopy (SEM) were performed on wrought and AM Haynes 188 in the virgin and long-term thermally exposed conditions. Mechanical test samples from the coupons were then extracted and tested in both conditions. Lastly, the fracture surfaces of the mechanical test specimens were evaluated by SEM fractography and metallography of sections through the fracture surfaces. The findings help to understand how long-term thermal exposure affects the microstructure and mechanical properties of wrought and AM Haynes 188. Most importantly, it illustrates a significant difference in microstructural response of the two materials to long term thermal exposure and its effect on mechanical properties.

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Henhoeffer, Thomas, Xiao Huang, Scott Yandt, and Peter Au. "Fatigue Properties of Narrow and Wide Gap Braze Repaired Joints." In ASME Turbo Expo 2010: Power for Land, Sea, and Air. ASMEDC, 2010. http://dx.doi.org/10.1115/gt2010-22085.

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With the increasing utilization of braze repair in the gas turbine industry, the properties of braze joints under simulated service conditions become vital in selecting braze repair over other processes. While braze repair has often been claimed to deliver mechanical properties equivalent to that of the parent material; this is largely based on the results of tensile or accelerated creep tests. For most gas turbine hot section components failure occurs as a result of thermal fatigue or thermomechanical fatigue. The damage that occurs under such conditions cannot be assessed from tensile or creep testing. This study was undertaken to characterize the fatigue properties of narrow and wide gap brazed X-40 cobalt-based superalloy and compare these properties to that of the X-40 parent material. Butt joint narrow gap and wide gap specimens were vacuum brazed using BNi-9 braze alloy. X-40 and IN-738 were used as additive materials in wide gap braze joints. To characterize the fatigue properties of the braze joints and parent material, isothermal fatigue tests were conducted at 950°C and under load control using a fully reversed sinusoidal wave form having stress amplitude of 75% of the yield strength of the parent material. The braze specimens were fatigue tested in the as-brazed condition. The fatigue test results showed the fatigue lives of the brazed specimens were lower than that of the parent material, particularly for the narrow gap samples and wide gap samples containing IN-738 additive alloy. All fatigue failures in the brazed samples occurred in the braze joints. Analysis of the fracture surfaces using SEM revealed that porosity was the major contributing factor to fatigue failures in the wide gap braze joints. The testing life debit observed in the narrow gap braze samples can be attributed to the presence of brittle boride phases in the braze joint. This study also included examination of techniques for reducing the aforementioned porosity and presence of brittle intermetallic phases.

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Pochet, Louis F., and Alfred L. Clavel. "The HF “Fluoride-Ion” Cleaning Technique for Superalloys." In ASME 1987 International Gas Turbine Conference and Exhibition. American Society of Mechanical Engineers, 1987. http://dx.doi.org/10.1115/87-gt-60.

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Fluoride-ion cleaning, using Hydrogen Fluoride gas as the active agent, is rapidly becoming established as a cost effective method to prepare nickel and cobalt based superalloys for braze repair. Background and comparative information on the four basic processes currently in use are discussed. The latest process using hydrogen fluoride gas directly is described in detail including the methods used for precise process control and safe handling of the HF input gas, as well as the off-gas fluoride compounds. Alloys successfully prepared for braze repair are listed. Other uses for the process and potential uses for the manufacture of new components are suggested.

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Guilemany, J. M., J. Nin, and J. R. Miguel. "New Powder Blends based on Cobalt Superalloys to Obtain Near-Net Shape Parts by HVOF." In ITSC2005, edited by E. Lugscheider. Verlag für Schweißen und verwandte Verfahren DVS-Verlag GmbH, 2005. http://dx.doi.org/10.31399/asm.cp.itsc2005p0036.

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Abstract The use of HVOF to produce surface coatings is much known. However, the spraying of inner parts or using it to reproduce a mold form is not always easy due to the high bonding strength of HVOF coatings. On the other hand, plasma formed parts are being used in the aerospatial industry for many years partly because the ease of the releasing process. Using the experience and the method developed in the CPT some years ago, some new materials have been sprayed to obtain thick axy-symmetrical self-standing forms. The process involves mechanical removal method and for these reason, the mould can be used several times with minimal maintenance. Amongst the releasing methods, the more simple is mechanical but it could turn out to be complex if the adhesion by impingement takes place too strongly. Hence, the impingement of the material is studied in this work. The materials are mechanical blends of WC-Co with Co-based alloys. However, prior to spraying, the most suitable material is chosen for a concrete purpose. The work includes a study of the spraying parameters in the structure and the properties of the coatings. XRD, SEM-EDS, roughness, microhardness, ASTM G 99-90 and ASTM G 65-91 wear test are performed to characterize the samples.

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Arjakine, Nikolai, Jerry Bruck, Birgit Gru¨ger, Dirk M. Seeger, and Rolf Wilkenhoener. "Advanced Weld Repair of Gas Turbine Hot Section Components." In ASME Turbo Expo 2008: Power for Land, Sea, and Air. ASMEDC, 2008. http://dx.doi.org/10.1115/gt2008-51534.

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In the 21st century, generation of electrical power will play a critical role due to constantly rising global population and increasing energy demand. While energy resources such as oil, coal and natural gas are being rapidly exhausted, environmental concerns of global warming due to CO2 emissions are simultaneously imposing limits on consumption of these limited resources. Natural gas is one of the most efficient industrial fuels and therefore, over the last two decades, its use with stationary gas turbines has increased dramatically. New nickel based superalloys and advanced coating systems have been introduced to further advance the efficiency of such natural gas power generation equipment. While such new technologies increase the cost of newly manufactured parts, refurbishment of service exposed parts has become of increasing importance in the gas turbine business. For this reason, for example, modern joining methods have been developed to repair single crystal parts at significantly lower prices compared to manufacture of new parts. Repair of turbine hot gas path components is a proven service offered to customers by Siemens Power Generation (Siemens PG). Highly advanced brazing and welding processes are routinely applied to repair gas turbine parts. Particular concerns in the repair of such turbine parts made of cobalt and nickel based superalloys include high susceptibility to hot cracking during welding and post weld heat treating. Special technological subtleties must be applied for successful repair including use of ductile filler materials, welding methods with low heat input, hot box welding and complicated pre- and post-weld heat treatments to avoid weld cracking. This paper deals with some repair welding technologies currently used at Siemens PG.

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Звіти організацій з теми "Cobalt-based Superalloy"

Dunand, David C., David N. Seidman, Christopher Wolverton, James E. Saal, Peter J. Bocchini, and Daniel J. Sauza. Designing Nanoscale Precipitates in Novel Cobalt-based Superalloys to Improve Creep Resistance and Operating Temperature. Office of Scientific and Technical Information (OSTI), October 2014. http://dx.doi.org/10.2172/1242420.

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