Journal articles: 'Cobalt base superalloys'

1

Klarstrom, D. L. "Wrought cobalt- base superalloys." Journal of Materials Engineering and Performance 2, no. 4 (August 1993): 523–30. http://dx.doi.org/10.1007/bf02661736.

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Suzuki, Akane, Haruyuki Inui, and Tresa M. Pollock. "L12-Strengthened Cobalt-Base Superalloys." Annual Review of Materials Research 45, no. 1 (July 2015): 345–68. http://dx.doi.org/10.1146/annurev-matsci-070214-021043.

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3

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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Shirzadi, A. A., and E. R. Wallach. "Novel Method for Diffusion Bonding Superalloys and Aluminium Alloys (USA Patent 6,669,534 B2, European Patent Pending)." Materials Science Forum 502 (December 2005): 431–36. http://dx.doi.org/10.4028/www.scientific.net/msf.502.431.

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A novel method for diffusion bonding metallic alloys with stable surface oxide films (e.g. nickel and cobalt base superalloys and aluminium alloys) has been developed. The stable oxides on the faying surfaces of these alloys are replaced, prior to the bonding process, with a very thin metallic layer and/or less stable oxides, using a proprietary non-chemical oxide removal method based on the use of gallium. This new method is very rapid and neither requires the use of any sophisticated equipment nor is a costly process. Bonding is then readily achieved by either solid-state or transient-liquid-phase (TLP) diffusion bonding. Using this method, bonds in nickelbase and cobalt-base superalloys with “virtually invisible” bond interfaces and bonds in aluminium alloys with strengths as high as those of the parent alloys can be produced.

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Yuan, Chao, Jian Ting Guo, and Lan Zhang Zhou. "Effect of Nitrogen on Microstructure and Properties of a Cast Cobalt-Base Superalloy." Advanced Materials Research 278 (July 2011): 472–78. http://dx.doi.org/10.4028/www.scientific.net/amr.278.472.

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The effect of the nitrogen on the microstructure and properties of a cast Co-based superalloy K640S was investigated with the different level ranged from 24 ppm to 85 ppm. The results indicate that almost all nitrogen exist in the form of nitride precipitation in the vacuum induction melting. It is found that high N level would extend the solidification window during the solidification process, and then increase the quantity of the carbide eutectic phases and led to the distribution in the network form of the eutectics in the interdendritic regions. High nitrogen content (more than 40 ppm) can reduced the mechanical properties of the testing alloy. So, it is suggested that the nitrogen in the recycled Co-based superalloys should be controlled at a suitable level in order to avoid the degradation of their properties.

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Kolb, Markus, Christopher H. Zenk, Anna Kirzinger, Ivan Povstugar, Dierk Raabe, Steffen Neumeier, and Mathias Göken. "Influence of rhenium on γ′-strengthened cobalt-base superalloys." Journal of Materials Research 32, no. 13 (July 2017): 2551–59. http://dx.doi.org/10.1557/jmr.2017.242.

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Kvapilová, Marie, Božena Podhorná, Jiri Dvorak, Petr Král, Jiří Zýka, Karel Hrbáček, and Vàclav Sklenička. "Creep Damage Mechanisms in Cast Cobalt Superalloys for Applications in Glass Industry." Key Engineering Materials 774 (August 2018): 173–78. http://dx.doi.org/10.4028/www.scientific.net/kem.774.173.

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Two cast NbC and TaC- strengthened cobalt-base superalloys have been developed for a precision casting of spinner discs for glass wool industry. In the present study, the relationships between the type and morphology of carbides and the degradation processes in both types of cast cobalt-based superalloys subjected to high temperature creep have been examined. It was found that the nature of carbides within the alloy microstructure plays a critical role in determining the creep damage processes and microstructure stability of the alloy system under high temperature creep. The morphology of the carbides is a strong function of their chemical composition. The interface decohesion between the complex carbides and the matrix and cracking of the brittle carbides homogeneously distributed in the crept NbC - strengthened alloy lead to brittle intergranular and/or interdendritic fracture. By contrast, Ta - strengthened alloy exhibited very small extent of isolated creep damage and the final fracture is ductile transgranular mode.

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8

Shahriary, M. S., Y. Miladi Gorji, and A. M. Kolagar. "Gas metal arc welding in refurbishment of cobalt base superalloys." IOP Conference Series: Materials Science and Engineering 164 (January 2017): 012016. http://dx.doi.org/10.1088/1757-899x/164/1/012016.

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9

Berthod, Patrice, Jean-Paul Gomis, Lionel Aranda, and Pierre-Jean Panteix. "Thermal Expansion and Microstructure Behavior at Elevated Temperature of various {Ni, Co}-based Cast Superalloys." Academic Journal of Chemistry, no. 53 (March 25, 2020): 17–24. http://dx.doi.org/10.32861/ajc.53.17.24.

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This paper aims to investigate the thermal expansion behavior, up to an elevated temperature, of superalloys based on nickel and cobalt with various proportions and designed to be strengthened by tantalum carbides. The as-cast microstructures of these superalloys and their evolutions at two very high temperatures were also of interest. All results are discussed by considering the Ni/Co repartition in the base element position. It appears that when the Ni content is higher than the Co one: 1/the thermal expansion is slower, 2/the as-cast microstructures as well as the ones stabilized at high temperature contain not only TaC but also chromium carbides, and 3/the hardness in as-cast or aged state is lower.

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10

Coedo, A. Gómez, M. T. Dorado López, and A. Vindel Maeso. "Inductively coupled plasma atomic emission spectrometric analysis of cobalt-base superalloys." J. Anal. At. Spectrom. 2, no. 6 (1987): 629–35. http://dx.doi.org/10.1039/ja9870200629.

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11

Lawen, J. L., S. J. Calabrese, and O. S. Dinc. "Wear Resistance of Super Alloys at Elevated Temperatures." Journal of Tribology 120, no. 2 (April 1, 1998): 339–44. http://dx.doi.org/10.1115/1.2834432.

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This paper provides the results of an extensive sliding wear testing program to evaluate wear resistance of several material couples currently used for high temperature applications such as ground based gas turbines and aircraft engines. Nickel and cobalt base superalloys and iron base stainless steels were tested in different combinations, and their wear rates compared to determine optimal wear resistance. The results show that an alloy’s wear resistance is highly dependent on operating temperature and its coupling with another material. The influences of friction, hardness, and oxide formation on the alloy’s wear resistance are also presented and discussed.

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12

Suzuki, Takanobu, Tadaharu Yokokawa, Toshiharu Kobayashi, Hiroshi Harada, and Hachiro Imai. "Effect of Cobalt on Micro-Structural Parameters of Ni-Base Single Crystal Superalloys." Journal of the Japan Institute of Metals 70, no. 2 (2006): 173–75. http://dx.doi.org/10.2320/jinstmet.70.173.

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13

Sun, Zhan, Xi Chen, Lixia Zhang, Saisai Zhang, and Jicai Feng. "Experimental and Numerical Study of Transient Liquid Phase Diffusion Bonded DZ40M Superalloys." Crystals 11, no. 5 (April 25, 2021): 479. http://dx.doi.org/10.3390/cryst11050479.

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Transient liquid phase (TLP) diffusion bonding of DZ40M cobalt-based superalloy was carried out using a self-made NiCrCoWB intermediate layer. The typical microstructure of the joint was investigated. The effect of holding time on the microstructural evolution and the tensile strength of the brazed joints was studied. The tensile strength of the joints TLP bonded at 1160 °C for 60 min reached the maximum value of 487 MPa, which was 88.6% of the base metal strength. The diffusion of boron and the evolution of the eutectic zone were numerically studied. The time needed for isothermal solidification completion was calculated and predicted, which was well in accordance with the experimental results.

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14

Goward, G. W., and L. W. Cannon. "Pack Cementation Coatings for Superalloys: A Review of History, Theory, and Practice." Journal of Engineering for Gas Turbines and Power 110, no. 1 (January 1, 1988): 150–54. http://dx.doi.org/10.1115/1.3240078.

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Nickel and cobalt-base superalloy blades and vanes in the hot sections of all gas turbines are coated to enhance resistance to hot corrosion. Pack cementation aluminizing, invented in 1911, is the most widely used coating process. Corrosion resistance of aluminide coatings can be increased by modification with chromium, platinum, or silicon. Chromium diffusion coatings can be used at lower temperatures. Formation and degradation mechanisms are reasonably well understood and large-scale manufacturing processes for these coatings are gradually being automated. Pack cementation and related diffusion coatings serve well for most aircraft engine applications. The trend for industrial and marine engines is more toward the use of overlay coatings because of the greater ease of designing these to meet a wide variety of corrosion conditions.

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15

Wang, W. Z., T. Jin, J. H. Jia, J. L. Liu, and Z. Q. Hu. "Effects of cobalt on creep rupture properties and dislocation structures in nickel base superalloys." Materials Science and Engineering: A 624 (January 2015): 220–28. http://dx.doi.org/10.1016/j.msea.2014.11.038.

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16

Neumeier, S., L. P. Freund, and M. Göken. "Novel wrought γ/γ′ cobalt base superalloys with high strength and improved oxidation resistance." Scripta Materialia 109 (December 2015): 104–7. http://dx.doi.org/10.1016/j.scriptamat.2015.07.030.

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17

Eggeler, Yolita M., Michael S. Titus, Akane Suzuki, and Tresa M. Pollock. "Creep deformation-induced antiphase boundaries in L1 2 -containing single-crystal cobalt-base superalloys." Acta Materialia 77 (September 2014): 352–59. http://dx.doi.org/10.1016/j.actamat.2014.04.037.

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18

Kolb, M., L. P. Freund, F. Fischer, I. Povstugar, S. K. Makineni, B. Gault, D. Raabe, et al. "On the grain boundary strengthening effect of boron in γ/γ′ Cobalt-base superalloys." Acta Materialia 145 (February 2018): 247–54. http://dx.doi.org/10.1016/j.actamat.2017.12.020.

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19

YANG, HO-YOUNG, JAE-HOON KIM, and KEUN-BONG YOO. "LOW CYCLE FATIGUE BEHAVIOR AND LIFE PREDICTION OF A CAST COBALT-BASED SUPERALLOY." International Journal of Modern Physics: Conference Series 06 (January 2012): 251–56. http://dx.doi.org/10.1142/s2010194512003261.

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Co -base superalloys have been applied in the stationary components of gas turbine owing to their excellent high temperature properties. Low cycle fatigue data on ECY-768 reported in a companion paper were used to evaluate fatigue life prediction models. In this study, low cycle fatigue tests are performed as the variables of total strain range and temperatures. The relations between plastic and total strain energy densities and number of cycles to failure are examined in order to predict the low cycle fatigue life of Cobalt-based super alloy at different temperatures. The fatigue lives is evaluated using predicted by Coffin-Manson method and strain energy methods is compared with the measured fatigue lives at different temperatures. The microstructure observing was performed for how affect able to low-cycle fatigue life by increasing the temperature.

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20

Pirowski, Z. "Thermal Analysis in the Technological “Step” Test of H282 Nickel Alloy." Archives of Foundry Engineering 15, no. 1 (March 1, 2015): 87–92. http://dx.doi.org/10.1515/afe-2015-0016.

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Abstract Superalloys show a good combination of mechanical strength and resistance to surface degradation under the influence of chemically active environments at high temperature. They are characterized by very high heat and creep resistance. Their main application is in gas turbines, chemical industry, and in all those cases where resistance to creep and the aggressive corrosion environment is required. Modern jet engines could never come into use if not for progress in the development of superalloys. Superalloys are based on iron, nickel and cobalt. The most common and the most interesting group includes superalloys based on nickel. They carry loads at temperatures well in excess of the eighty percent of the melting point. This group includes the H282 alloy, whose nominal chemical composition is as follows (wt%): Ni - base, Fe - max. 1.5%, Al - 1.5% Ti - 2.1%, C - 0.06% Co - 10% Cr - 20% Mo - 8.5%. This study shows the results of thermal analysis of the H282 alloy performed on a cast step block with different wall thickness. Using the results of measurements, changes in the temperature of H282 alloy during its solidification were determined, and the relationship dT / dt = f (t) was derived. The results of the measurements taken at different points in the cast step block allowed identifying a number of thermal characteristics of the investigated alloy and linking the size of the dendrites formed in a metal matrix (DAS) with the thermal effect of solidification. It was found that the time of solidification prolonged from less than ome minute at 10 mm wall thickness to over seven minutes at the wall thickness of 44 mm doubled the value of DAS.

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21

Suzuki, Takanobu, Tadaharu Yokokawa, Toshiharu Kobayashi, Yutaka Koizumi, Hiroshi Harada, and Hachiro Imai. "Effect of Cobalt on Microstructural Parameters and Mechanical Properties of Ni-Base Single Crystal Superalloys." Journal of the Japan Institute of Metals 71, no. 2 (2007): 233–38. http://dx.doi.org/10.2320/jinstmet.71.233.

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22

Tanaka, Manabu. "Improvement of Creep-Rupture Properties by Serrated Grain Boundaries in Hish-Tungsten Cobalt-Base Superalloys." International Journal of Materials Research 84, no. 1 (January 1, 1993): 51–56. http://dx.doi.org/10.1515/ijmr-1993-840110.

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23

Berthod, P., S. Michon, L. Aranda, S. Mathieu, and J. C. Gachon. "Experimental and thermodynamic study of the microstructure evolution in cobalt-base superalloys at high temperature." Calphad 27, no. 4 (December 2003): 353–59. http://dx.doi.org/10.1016/j.calphad.2004.01.001.

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24

ARAI, Takashi, Toshiharu KOBAYASHI, Takehiko ITAGAKI, Kisaburo KOIKE, and Nobuo SAKUMA. "Production of Tungsten Wire Reinforced Cobalt Base Superalloys by Vacuum Casting and Their Creep Rupture Properties." Tetsu-to-Hagane 73, no. 10 (1987): 1389–96. http://dx.doi.org/10.2355/tetsutohagane1955.73.10_1389.

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25

Tanaka, M. "Effects of high-temperature ageing on the creep-rupture properties of high-tungsten cobalt-base superalloys." Journal of Materials Science 29, no. 10 (May 1994): 2620–28. http://dx.doi.org/10.1007/bf00356809.

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26

Nathal, M. V., and L. J. Ebert. "The influence of cobalt, tantalum, and tungsten on the microstructure of single crystal nickel-base superalloys." Metallurgical Transactions A 16, no. 10 (October 1985): 1849–62. http://dx.doi.org/10.1007/bf02670372.

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27

Weiser, Martin, Angelika Reichmann, Mihaela Albu, Sannakaisa Virtanen, and Peter Poelt. "In Situ Investigation of the Oxidation of Cobalt-Base Superalloys in the Environmental Scanning Electron Microscope." Advanced Engineering Materials 17, no. 8 (July 7, 2015): 1158–67. http://dx.doi.org/10.1002/adem.201500146.

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28

Mughrabi, Haël. "The importance of sign and magnitude of γ/γ′ lattice misfit in superalloys—with special reference to the new γ′-hardened cobalt-base superalloys." Acta Materialia 81 (December 2014): 21–29. http://dx.doi.org/10.1016/j.actamat.2014.08.005.

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29

Berthod, P., S. Raude, A. Chiaravalle, A. S. Renck, C. Rapin, and R. Podor. "Influence of the microstructure texture of nickel base and cobalt base cast superalloys on their oxdation behaviour at high temperature." Revue de Métallurgie 101, no. 12 (December 2004): 1031–42. http://dx.doi.org/10.1051/metal:2004109.

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30

Devaux, Alexander, Eric Georges, and Philippe Héritier. "Development of New C&W Superalloys for High Temperature Disk Applications." Advanced Materials Research 278 (July 2011): 405–10. http://dx.doi.org/10.4028/www.scientific.net/amr.278.405.

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The enhancement of efficiency in gas turbine engines requires the development of new superalloys capable of withstanding higher temperatures. The development of novel industrial cast and wrought (C&W) disk alloys with required combination of strength, creep and fatigue resistances at 700°C is particularly desired due to the expensive cost of powder metallurgy. In this context, new C&W disk alloys were recently developed to fulfill these requirements. TMW4 shows higher properties than the current C&W disk alloy despite an expensive cost due to its high cobalt content, where as 718Plus presents a moderate cost with restricted creep properties at 700°C compared to the current U720Li disk alloy. The new nickel base superalloys developed by Aubert & Duval were therefore designed to offer a better compromise between high temperature properties at 700°C and cost. This paper describes the alloy metallurgical features and is especially focused on the alloy design which is extensively based on phase diagram modeling. The study was firstly carried out on small ingots of 6 kg to optimize the chemistry before forging 200 kg ingots by industrial processes. The ability to be processed by the conventional cast & wrought route and the control of the highly expensive elements contents confer to the alloys an attractive cost comparable to that of 718Plus alloy. The high amount of ’ and the molybdenum-tungsten levels insure higher creep and tensile properties than those obtained with 718Plus.

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31

Bobeck, Gene E., and R. V. Miner. "Effects of cobalt concentration on the relative resistance to octahedral and cube slip in nickel-base superalloys." Metallurgical Transactions A 19, no. 11 (November 1988): 2733–39. http://dx.doi.org/10.1007/bf02645808.

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32

Tarasova, T. V., A. P. Nazarov, and M. V. Prokof’ev. "Effect of the regimes of selective laser melting on the structure and physicomechanical properties of cobalt-base superalloys." Physics of Metals and Metallography 116, no. 6 (June 2015): 601–5. http://dx.doi.org/10.1134/s0031918x15060101.

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33

Naalchian, Mojtaba, Masoud Kasiri-Asgarani, Morteza Shamanian, Reza Bakhtiari, Hamid Reza Bakhsheshi-Rad, Filippo Berto, and Oisik Das. "Phase Formation during Heating of Amorphous Nickel-Based BNi-3 for Joining of Dissimilar Cobalt-Based Superalloys." Materials 14, no. 16 (August 16, 2021): 4600. http://dx.doi.org/10.3390/ma14164600.

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Phase transformations and the melting range of the interlayer BNi-3 were investigated by differential scanning calorimetry, which showed three stages of crystallization during heating. There were three exothermic peaks that indicated crystallization in the solid state. The cobalt-based X-45 and FSX-414 superalloys were bonded with interlayer BNi-3 at a constant holding time of 10 min with bonding temperatures of 1010, 1050, 1100, and 1150 °C using a vacuum diffusion brazing process. Examination of microstructural changes in the base metals with light microscopy and scanning electron microscopy coupled with X-ray spectroscopy based on the energy distribution showed that increasing temperature caused a solidification mode, such that the bonding centerline at 1010 °C/10 min included a γ-solid solution, Ni3B, Ni6Si2B, and Ni3Si. The athermally solidified zone of the transient liquid phase (TLP)-bonded sample at 1050 °C/10 min involved a γ-solid solution, Ni3B, CrB, Ni6Si2B, and Ni3Si. Finally, isothermal solidification was completed within 10 min at 1150 °C. The diffusion-affected zones on both sides had three distinct zones: a coarse block precipitation zone, a fine and needle-like mixed-precipitation zone, and a needle-like precipitation zone. By increasing the bonding temperature, the diffusion-affected zone became wider and led to dissolution.

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34

Liang, Zhida, Mathias Göken, Uwe Lorenz, Steffen Neumeier, Michael Oehring, Florian Pyczak, Andreas Stark, and Li Wang. "Influence of small amounts of Si and Cr on the high temperature oxidation behavior of novel cobalt base superalloys." Corrosion Science 184 (May 2021): 109388. http://dx.doi.org/10.1016/j.corsci.2021.109388.

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35

Zhang, Yi, Huadong Fu, Xiaozhou Zhou, Yuheng Zhang, and Jianxin Xie. "Effects of aluminum and molybdenum content on the microstructure and properties of multi-component γ′-strengthened cobalt-base superalloys." Materials Science and Engineering: A 737 (November 2018): 265–73. http://dx.doi.org/10.1016/j.msea.2018.09.058.

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Wang, Y. Q., and G. Sayre. "Synthesis of simple and platinum-modified aluminide coatings on cobalt (Co)-base superalloys via a vapor phase aluminizing process." Surface and Coatings Technology 203, no. 3-4 (November 2008): 256–63. http://dx.doi.org/10.1016/j.surfcoat.2008.08.072.

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37

Nathal, M. V., and L. J. Ebert. "The influence of cobalt, tantalum, and tungsten on the elevated temperature mechanical properties of single crystal nickel-base superalloys." Metallurgical Transactions A 16, no. 10 (October 1985): 1863–70. http://dx.doi.org/10.1007/bf02670373.

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38

Zhou, Xiaozhou, Huadong Fu, Yi Zhang, Huan Xu, and Jianxin Xie. "Effect of Al and W Contents on the Solidification and Solution Microstructure of Novel γ / γ ′ Cobalt‐Base Superalloys." Advanced Engineering Materials 21, no. 12 (October 17, 2019): 1900641. http://dx.doi.org/10.1002/adem.201900641.

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Ma, Chunmei, Songting Yang, Yuheng Zhang, Kaikun Wang, and Huadong Fu. "Effects of temperature and Ti addition on high-temperature oxidation behaviors of Co-Al-W based superalloys." Anti-Corrosion Methods and Materials 67, no. 5 (June 29, 2020): 445–51. http://dx.doi.org/10.1108/acmm-04-2020-2298.

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Purpose Due to the special service environment of superalloys, this paper aims to obtain effects of temperature and Ti addition on high temperature oxidation behavior of Co-Al-W-B alloys. Design/methodology/approach Isothermal oxidation experiment of Co-Al-W-based alloys were carried out at 800°C, 900°C and 1000°C for different times (3, 5, 10, 20, 50 and 100 h) referring to the method of HB5258-2000. Oxidation weight gain curves and oxidation products were detected. Findings The results showed that the average oxidation rates of Co-Al-W-B alloy at 800 °C and 900 °C were 0.489 g·m−2·h−1 and 0.888 g·m−2·h−1, respectively, which belonged to an antioxidant grade. However, the average oxidation rate at 1000 °C was 2.068 g m−2·h−1, belonging to the secondary oxidation resistance class. In the alloy with Ti addition, dense Ti oxides film were formed at the early oxidation stage and then gradually diffused later, which can increase the oxidation resistance of the alloys to some extent. By analyzing the oxidation products of Co-Al-W-B alloy, it was found that a dense Al2O3 layer could be formed when the alloy was oxidized at 800°C. The continuous Al2O3 layer would prevent the oxygen from further spreading and make the alloy into the stable oxidation stage. However, only a non-dense Al2O3 layer were observed with 900°C oxidation. Originality/value It can provide references for the composition design, preparation process optimization and protective coating selection of the γ′ phase strengthened cobalt-base superalloys.

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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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A. Saleh, Khudhur, Mahmood A. Hamood, and Nawfal Y. Jahmeel. "EFFECT OF HOT CORROSION AND OXIDATION ON COBALT - BASE SUPERALLOYS COATED BY ALUMINUM WITH PRESENCE OF THERMAL BARRIER ZRO2 AND MIXTURE OF (NACL) AND (NA2SO4) STEAMSALTSAT HIGH TEMPERATURES." International Journal of Advanced Research 9, no. 07 (July 31, 2021): 954–69. http://dx.doi.org/10.21474/ijar01/13198.

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The aim of the study was to investigate the Mechanisms properties of thermal barrier coatings (TBCs) to enhance of performance evaluation characteristics and develop TBCs.Cobalt Ã¢Â€Â“base superalloy has been used as a substrate and zirconium stabilized Aluminum as ceramic topcoat , in addition the study include degradation behavior of system during thermal cycling (3hr per cycle in furnace) the failure of the aluminized was due to thermally grown oxide (TGO) interface. The fractures propagatethrough the interface and produce a deformation of the bond coating . the effect of cycle will result a spallation failure of the TBCsand this is also corresponding to a slightdegradation .The steam of salt (Nacl)and(Na2So4) mixture will affecton the coating lifetimes .The high temperature have a strong effect thermally grown oxide (TGO) which consistent with a first order growth of scale failer variation.

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42

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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Bezold, A., N. Volz, F. Xue, C. H. Zenk, S. Neumeier, and M. Göken. "On the Precipitation-Strengthening Contribution of the Ta-Containing Co3(Al,W)-Phase to the Creep Properties of γ/γ′ Cobalt-Base Superalloys." Metallurgical and Materials Transactions A 51, no. 4 (January 21, 2020): 1567–74. http://dx.doi.org/10.1007/s11661-020-05626-2.

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Berthod, Patrice, Merzouk Bouaraba, and Junfu Cai. "Influence of the Chromium Content on the Characteristics of the Matrix, the Tantalum Carbides Population, and the Hardness of Cast Co(Cr)-0.4C-6Ta Alloys." Micro 3, no. 1 (February 16, 2023): 239–55. http://dx.doi.org/10.3390/micro3010017.

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The mechanical and chemical behaviors of cast cobalt-base superalloys are governed by the carbides and by a reactive element, which is often chromium. The content of this later element, which is efficient in resisting hot oxidation and also hot corrosion, may have consequences on the melting temperature, microstructure, and mechanical properties at high temperatures and at room temperature. Seemingly, the effect of chromium content on the microstructure and properties of cast equi-axed Co-Cr-Ta-C superalloys containing TaC as single reinforcing carbide and in high-enough quantities to achieve a high level of creep resistance has not been the subject of previous investigations. The present work is devoted to the exploration of this influence of Cr content on the as-cast microstructure of a model alloy in this category, as well as on its microstructure transformations at high temperatures. The work aims to help rate the Cr content to achieve the best characteristics in machinability and high-temperature properties. This is of great importance for fabricability (production cost) and sustainability in service (long enough lifetime performance). A series of six alloys derived from a rather well-known alloy and presenting various Cr contents were thus elaborated by casting. Their microstructures were investigated in their as-cast state as well as in an aged state resulting from a 4-day stage at 1400 K. Vickers indentation was also carried out to study how hardness may evolve with Cr content. It was seen that the higher the Cr content, the lower the solidus temperature, the coarser the TaC population, the harder the alloy, and the higher the risk of brittleness. In order to reach the best compromise, the preferred Cr weight content range, as identified by this work, is 20–30%; indeed, for such Cr contents: (1) the matrix is austenitic, then dense, and then hard and not brittle, and thus is mechanically resistant and tough; (2) the TaC carbides are script-shaped and resistant against morphology changes at high temperatures, and thus efficiently preserve interdendritic cohesion for a long time, and, consequently, (3) the alloys are machinable, have expected good toughness, and can be resistant against creep deformation as well as oxidation and corrosion at high temperatures thanks to the Cr content, allowing for chromium-forming behavior.

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Liu, Xingjun, Yunwei Pan, Yuechao Chen, Jiajia Han, Shuiyuan Yang, Jingjing Ruan, Cuiping Wang, Yuansheng Yang, and Yingju Li. "Effects of Nb and W Additions on the Microstructures and Mechanical Properties of Novel γ/γ’ Co-V-Ti-Based Superalloys." Metals 8, no. 7 (July 23, 2018): 563. http://dx.doi.org/10.3390/met8070563.

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Microstructures, elemental partition behavior, phase stabilities and mechanical properties of Nb- and W-containing Co-V-Ti-based superalloys were investigated. Elemental partition coefficients (KX = Cγ’/Cγ) of Nb and W in Co-V-Ti-based superalloys are 2.07 and 1.10, respectively. The γ’ solvus temperatures are determined as 1023 °C, 1055 °C and 1035 °C in Co-12V-4Ti, Co-10V-4Ti-2Nb and Co-10V-4Ti-2W alloys, which are higher than those of Co-9Al-9W alloy (1000 °C). The mass densities of quaternary Co-10V-4Ti-2Nb and Co-10V-4Ti-2W alloys are about 8.31 and 8.50 g·cm−3, respectively, which are 15% lower than Co-Al-W-based superalloys (9.8 g·cm−3). All examined alloys exhibit an anomalous positive dependence on temperature rising from 600 to 750 °C. Strengths of all examined alloys are higher than those of MarM509 (traditional Cobalt-based superalloy) and Co-9Al-9W at all temperatures that we investigated. The maximum flow stress of Co-V-Ti-Nb alloy is about 638 MPa at 750 °C while that of Co-V-Ti-W alloy is about 588 MPa at 700 °C.

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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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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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Xi, Shengkun, Jinxin Yu, Longke Bao, Liuping Chen, Zhou Li, Rongpei Shi, Cuiping Wang, and Xingjun Liu. "Machine learning-accelerated first-principles predictions of the stability and mechanical properties of L12-strengthened cobalt-based superalloys." Journal of Materials Informatics 2, no. 3 (2022): 15. http://dx.doi.org/10.20517/jmi.2022.22.

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As promising next-generation candidates for applications in aero-engines, L12-strengthened cobalt (Co)-based superalloys have attracted extensive attention. However, the L12 strengthening phase in first-generation Co-Al-W-based superalloys is metastable and both its solvus temperature and mechanical properties still need to be improved. Therefore, it is necessary to discover new L12-strengthened Co-based superalloy systems with a stable L12 phase by exploring the effect of alloying elements on its stability. Traditional first-principles calculations are capable of providing the crystal structure and mechanical properties of the L12 phase doped by transition metals but suffer from low efficiency and relatively high computational costs. The present study combines machine learning (ML) with first-principles calculations to accelerate crystal structure and mechanical property predictions, with the latter providing both the training and validation datasets. Three ML models are established and trained for predicting the occupancy of alloying elements in the supercell and the stability and the mechanical properties of the L12 phase. The ML predictions are evaluated using first-principles calculations and the accompanying data are used to further refine the ML models. Our ML-accelerated first-principles calculation approach offers more efficient predictions of the crystal structure and mechanical properties for Co-V-Ta- and Co-Al-V-based systems than the traditional counterpart. This approach is applicable to expediting crystal structure and mechanical property calculations and thus the design and discovery of other advanced materials beyond Co-based superalloys.

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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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Leni, Desmarita, Yuda Perdana Kusuma, Muchlisinalahuddin Muchlisinalahuddin, Ruzita Sumiati, and Hendri Candra Mayana. "THE IMPLEMENTATION OF PANDAS PROFILING AS A TOOL FOR ANALYZING MECHANICAL PROPERTIES DATA OF NICKEL-BASED SUPERALLOYS BASED ON ALLOY CHEMICAL COMPOSITION." International Journal of Innovation in Mechanical Engineering and Advanced Materials 4, no. 3 (May 31, 2023): 86. http://dx.doi.org/10.22441/ijimeam.v4i3.19439.

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The purpose of this study is to evaluate the mechanical properties of nickel-based superalloys with variations in alloy chemical compositions using the Exploratory Data Analysis (EDA) method with the assistance of the pandas profiling library on Google Colab. In this study, data from 312 tensile tests of nickel-based superalloys were used as research samples, with alloy chemical compositions including carbon (C), manganese (Mn), silicon (Si), chromium (Cr), nickel (Ni), molybdenum (Mo), vanadium (V), nitrogen (N), niobium (Nb), cobalt (Co), tungsten (W), aluminum (Al), and titanium (Ti), as well as mechanical properties such as yield strength (YS), tensile strength (TS), and elongation (EL). The methodology used in this study was the EDA method with the assistance of the pandas profiling library on Google Colab, which enables the automatic creation of a dataset report, presenting information on various aspects such as data structure, descriptive statistics, correlation, distribution, and missing values. The results show that yield strength has a fairly high correlation with titanium (0.51), medium correlations with nickel (0.25), vanadium (0.2), and cobalt (0.2). Tensile strength in nickel-based superalloys has a fairly high correlation with yield strength (0.88), carbon (0.49), and cobalt (0.55), and medium correlations with titanium (0.25) and vanadium (0.25). Elongation in nickel-based superalloys has a negative and fairly high correlation with tensile strength (-0.62) and yield strength (-0.58). Some warnings for missing data and zero values in some variables were identified. These results indicate that the pandas profiling library can be used as a tool to analyze the data of mechanical properties of nickel-based superalloys quickly and easily, and provide clear information on data patterns, data structure, and correlation among data.

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Journal articles on the topic 'Cobalt base superalloys'

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