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1

Yao, Qiang, Yan Wang, Yu Hong Zhu, and Xiao Lin Zhu. "First-Principles Investigation of the Site Occupancy and Elastic Properties of Y in γ-Co3(Al,W)." Materials Science Forum 788 (April 2014): 473–76. http://dx.doi.org/10.4028/www.scientific.net/msf.788.473.

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Site occupancy of Y in the γ′-Co3(Al,W) was predicted theoretically by first-principles calculations based on density functional theory. By computing total energy as a function of applied strain, the elastic constants of quaternary Co3(Al,W) were also predicted. The results suggest that Y preferentially occupies the W sites in Co3(Al,W). The calculation of heat of formation shows that the occupancy of Y on the W sites decreases the phase stability of Co3(Al,W). The theoretical calculation also shows that the L12 Co24Al4W3Y compound is ductile in nature.
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2

Inui, Haruyuki, Takashi Oohashi, Norihiko L. Okamoto, Kyosuke Kishida, and Katsushi Tanaka. "Physical and Mechanical Properties of Co3(Al,W) with the L12 Structure in Single and Polycrystalline Forms." Key Engineering Materials 465 (January 2011): 9–14. http://dx.doi.org/10.4028/www.scientific.net/kem.465.9.

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The physical and mechanical properties of Co3(Al,W) with the L12 structure have been investigated both in single and polycrystalline forms. The values of all the three independent single-crystal elastic constants and polycrystalline elastic constants of Co3(Al,W) experimentally determined by resonance ultrasound spectroscopy at liquid helium temperature are 15~25% larger than those of Ni3(Al,Ta) but are considerably smaller than those previously calculated. When judged from the values of Poisson’s ratio, Cauchy pressure and Gh (shear modulus)/Bh (bulk modulus), the ductility of Co3(Al,W) is expected to be sufficiently high. Indeed, the value of tensile elongation obtained in air is as large as 28 %, which is far larger than that obtained in Ni3Al polycrystals under similar conditions.
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3

Yao, Qiang, Tong Lu, Qiong Wang, Yan Wang, and Yu Hong Zhu. "First-Principles Investigation of Phase Stability, Elastic and Thermodynamic Properties in L12 Co3(Al,Mo,Ta) Phase." Materials Science Forum 898 (June 2017): 438–45. http://dx.doi.org/10.4028/www.scientific.net/msf.898.438.

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First-principles calculations have been performed to investigate the phase stability, elastic, and thermodynamic properties of Co3(Al,Mo,Ta) with the L12 structure. Calculated elastic constants showed that Co3(Al,Mo,Ta) is mechanically stable and possesses intrinsic ductility. Young’s and shear moduli of polycrystalline Co3(Al,Mo,Ta) were calculated using the Voigt-Reuss-Hill approach. It was found that the shear and Young’s moduli of Co3(Al,Mo,Ta) were smaller than those of Co3(Al,W). States density indicated the existence of covalent-like bonding in Co3(Al,Mo,Ta). Temperature-dependent thermodynamic properties of Co3(Al,Mo,Ta) could be described satisfactorily using the Debye-Grüneisen approach, including entropy, enthalpy, heat capacity and linear thermal expansion coefficient, showing their significant temperature dependences. Furthermore the obtained data could be employed in the modeling of thermodynamic and mechanical properties of Co-based alloys to enable the design of high temperature alloys.
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4

Inui, Haruyuki, Takashi Oohashi, Norihiko L. Okamoto, Kyosuke Kishida, and Katsushi Tanaka. "Mechanical Properties of the Ternary L12 Compound Co3(Al,W) in Single and Polycrystalline Forms." Advanced Materials Research 278 (July 2011): 1–6. http://dx.doi.org/10.4028/www.scientific.net/amr.278.1.

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The mechanical properties of Co3(Al,W) with the L12 structure have been investigated both in single and polycrystalline forms. The values of all the three independent single-crystal elastic constants and polycrystalline elastic constants of Co3(Al,W) experimentally determined by resonance ultrasound spectroscopy at liquid helium temperature are 15~25% larger than those of Ni3(Al,Ta) but are considerably smaller than those previously calculated. When judged from the values of Poisson’s ratio, Cauchy pressure and ratio of shear modulus to bulk modulus (Gh/Bh), the ductility of Co3(Al,W) is expected to be sufficiently high. In the yield stress-temperature curve, a rapid decrease and an anomalous increase in yield stress is observed in the low and intermediate (1000-1100 K) temperature ranges, respectively. The former is concluded to be due to the solid-solution hardening effect while the latter is attributed to thermally activated cross-slip of APB-coupled a/2<110> superpartial dislocations from octahedral to cube slip planes.
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5

Romanov, E. P., N. V. Kazantseva, N. N. Stepanova, S. L. Demakov, D. I. Davydov, and D. A. Shishkin. "Heat-resistant alloys based on intermetallic Co3(Al, W)." Doklady Chemistry 473, no. 2 (April 2017): 88–91. http://dx.doi.org/10.1134/s0012500817040036.

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6

Davidov, D. I., Igor Ezhov, Nikolay A. Popov, and Nataliya Kazantseva. "Mechanical Properties of Co-Al-Mo-Nb Intermetallic Alloys." Key Engineering Materials 910 (February 15, 2022): 1121–26. http://dx.doi.org/10.4028/p-3102k8.

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The results of the experimental study of the mechanical properties and structure of the Co-9.5Al-2.9Mo-4Nb, Co-9.1Al-5.2Mo-4.7Nb, and Co-8.9Al-6.5Mo-9.3Nb alloys were presented. The Young’s moduli in the studied alloy samples were found to be smaller than those of Ni3Al-based and Co3(Al,W)-based alloys. The eutectic structure was observed in all studied alloys. Cuboids of the Co3(Al,Nb,Mo) intermetallic compound with L12 crystal structure were found by TEM study.
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7

Yamanaka, Syuki, Ken-ichi Ikeda, and Seiji Miura. "Effect of Multi-Elements Substitution on the Mechanical Properties of Intermetallic Compound." MRS Advances 4, no. 25-26 (2019): 1497–502. http://dx.doi.org/10.1557/adv.2019.119.

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ABSTRACTIt is well known that various elements substitute for a certain sub-lattice of intermetallic compounds. There have been various experimental investigations of the effects of substituted elements on mechanical properties, however, there are few reports describing the effects of multi-element substitution. In the present study, L12-type compounds A3B (Ni3Al and Co3(Al,W)) were selected as model compounds because their substitution behavior is well known. It was reported that various elements such as Ni, Co, Cu, Pd and Pt occupy the A-site, whereas Al, Si, Ga, Ge, Ti, V, Nb, Ta, Mo, and W occupy the B-site. These elements are expected to introduce local lattice distortion, which may affect the motion of dislocations over a wide range of temperatures. Several alloys composed of five or more elements including Ni, Co, Al, Mo, and W, were prepared using an Ar-arc melting machine and heat-treated. Several alloys were found to include an (Ni, Co)3(Al, Mo, W, …)-L12 compound as a constituent phase. The nano-hardness of these L12 phases was higher than that of the high-strength Co3(Al,W)-L12 compound, confirming that multi-element substitution is an effective way to improve the mechanical properties of an intermetallic compound without decreasing the phase stability.
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8

Inui, Haruyuki, Takashi Oohashi, Norihiko L. Okamoto, Kyosuke Kishida, and Katsushi Tanaka. "Physical and Mechanical Properties of Single Crystals of Co-Al-W Based Alloys with L12 Single-Phase and L12/fcc Two-Phase Microstructures." Materials Science Forum 638-642 (January 2010): 1342–47. http://dx.doi.org/10.4028/www.scientific.net/msf.638-642.1342.

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The values of all the three independent single-crystal elastic constants and polycrystalline elastic constants of Co3(Al,W) experimentally determined by resonance ultrasound spectroscopy at liquid helium temperature are 15~25% larger than those of Ni3(Al,Ta) but are considerably smaller than those previously calculated. Because of the large value of E111/E100 and cij of Co3(Al,W), two-phase microstructures with cuboidal L12 precipitates well aligned parallel to <100> and well faceted parallel to {100} are expected to form very easily in Co-base alloys, as confirmed indeed by experiment. Values of yield stress obtained for [001]-oriented L12/fcc two-phase single crystals moderately decrease with the increase in temperature up to 800°C and then decrease rapidly with temperature above 800°C without any anomaly in yield stress.
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9

Okamoto, Norihiko L., Takashi Oohashi, Hiroki Adachi, Kyosuke Kishida, Haruyuki Inui, and Patrick Veyssière. "Plastic deformation of polycrystals of Co3(Al,W) with the L12structure." Philosophical Magazine 91, no. 28 (October 2011): 3667–84. http://dx.doi.org/10.1080/14786435.2011.586158.

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10

Wang, Dong, Yongsheng Li, Shujing Shi, and Xinwen Tong. "Element migration during stress rafting of γ′-Co3(Al, W) precipitates." Philosophical Magazine Letters 100, no. 5 (March 17, 2020): 202–12. http://dx.doi.org/10.1080/09500839.2020.1741043.

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11

Saal, James E., and C. Wolverton. "Energetics of antiphase boundaries in γ′ Co3(Al,W)-based superalloys." Acta Materialia 103 (January 2016): 57–62. http://dx.doi.org/10.1016/j.actamat.2015.10.007.

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12

Казанцева, Н. В., С. Л. Демаков, А. С. Юровских, Н. Н. Степанова, Н. И. Виноградова, Д. И. Давыдов, and С. В. Лепихин. "Исследование диаграммы состояния Co–Al–W. Структура и фазовые превращения вблизи концентрационной области существования интерметаллида Co3(Al, W)." Физика металлов и металловедение 117, no. 7 (2016): 723–31. http://dx.doi.org/10.7868/s001532301607007x.

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13

Tsukamoto, Yuki, Satoru Kobayashi, and Takayuki Takasugi. "The Stability of γ ’-Co3(Al,W) Phase in Co-Al-W Ternary System." Materials Science Forum 654-656 (June 2010): 448–51. http://dx.doi.org/10.4028/www.scientific.net/msf.654-656.448.

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The thermodynamic stability ’- Co3(Al,W) phase (L12) in the Co-Al-W ternary system at 900 °C was investigated through microstructure and EPMA analysis on a heat-treated bulk alloy. To promote microstructural evolution, the bulk alloy was cold rolled before heat treatment. By heating at 900 °C, the ’ phase was formed discontinuously in contact with the -Co (A1) phase. With increasing heat treatment time, however, the fraction of ’ phase decreased while that of , CoAl (B2) and Co3W (D019) phases increased. These results are consistent with our previous work with a diffusion-couple method, indicating that the ’ phase is metastable, and the three phases of, CoAl and Co3W are thermodynamically stable at 900 °C.
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14

Shi, Shujing, Zhengwei Yan, Yongsheng Li, Dong Wang, Zhiheng An, Gang Sha, Yang Wang, and Yan Zhao. "Precipitation kinetics and morphology evolution of the Co3(Al, W) phase in a medium supersaturation Co–Al–W alloy." Journal of Materials Science 56, no. 3 (October 12, 2020): 2597–611. http://dx.doi.org/10.1007/s10853-020-05379-8.

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15

Tanaka, Katsushi, Takashi Ohashi, Kyosuke Kishida, and Haruyuki Inui. "Single-crystal elastic constants of Co3(Al,W) with the L12 structure." Applied Physics Letters 91, no. 18 (October 29, 2007): 181907. http://dx.doi.org/10.1063/1.2805020.

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16

Zhao, Wen Jun, and Yang Tao Xu. "Alloying Element Ta Effect on Microstructure of Co-Al-W Superalloy by Vacuum Arc Melting." Advanced Materials Research 718-720 (July 2013): 10–13. http://dx.doi.org/10.4028/www.scientific.net/amr.718-720.10.

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Co-based high temperature alloys have been widely used in aeronautics and astronautics industry, because of its high strength at high temperature, excellent resistance of hot corrosion and oxidation. Unlike the traditional Co-based superalloys, strengthened by solution and carbide strengthening, the novel Co-Al-W superalloys are strengthened by a ternary compound with the Ll2 structure γ-Co3(Al,W). And the novel Co-Al-W superalloys showing high-temperature strength greater than those of conventional nickel-base superalloys, will become the candidates for next-generation high-temperature materials. We research alloying element Ta effect on microstructure of Co-Al-W superalloys by vacuum arc melting. Compare with the microstructure before and after adding alloying element Ta of Co-Al-W superalloy, we find that most of Ta element distributed in the γ-Co substrate phase, stabilizing and reinforcement the γ phase.
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17

Xu, Yang Tao, Qi Zhen Sha, and Wan Li Zhao. "Study on Microstructure and Phase Composition of Co-8.8Al-9.8W Superalloy with Alloying Element Tantalum." Advanced Materials Research 1083 (January 2015): 37–39. http://dx.doi.org/10.4028/www.scientific.net/amr.1083.37.

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In order to study the effect of tantalum to the microstructure and phase composition of Co-8.8Al-9.8W-XTa (X=0,2,at%) superalloy. The Co-8.8Al-9.8W-XTa (X=0,2) supperalloy used pure element powder, according to the ratio of different atomic percentage composition to make ingredients. It is mixed by planetary ball mill, pressed into blocks after the melting shape. Vacuum induction melting process was prepared by melting, after grinding, polishing, and after a volume of 5% perchloric acid and 95% of the electrolytic etching solution prepared in ethanol corrosion observed after analysis of the microstructure and phase composition by OM and XRD analysis. It can be found that the 9.8W and 2Ta alloy were mainly composed of rich γ-Co matrix of austenite precipitation of γ phase and coherent with matrix of the L12 structure of γ′-Co3(Al,W) phase. In addition, Ta element has effect on grain refinement and the number of γ′-Co3(Al,W) phase refines grain.
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18

Kazantseva, N. V., S. L. Demakov, A. S. Yurovskikh, N. N. Stepanova, N. I. Vinogradova, D. I. Davydov, and S. V. Lepikhin. "Phase diagram of the Co–Al–W system. structure and phase transformations near the Co3(Al, W) intermetallic composition range." Physics of Metals and Metallography 117, no. 7 (July 2016): 701–9. http://dx.doi.org/10.1134/s0031918x16070073.

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19

Xu, Yang Tao, Tian Dong Xia, Wen Jun Zhao, and Xiao Jun Wang. "Alloying Element Nb Effect on Microstructure of Co-Al-W Superalloy by Vacuum Arc Melting." Applied Mechanics and Materials 229-231 (November 2012): 63–67. http://dx.doi.org/10.4028/www.scientific.net/amm.229-231.63.

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Co-Al-W supperalloy used pure element powder, according to the ratio of different atomic percentage composition to make ingredients. It is mixed by planetary ball mill, pressed into blocks after the melting shape. Vacuum arc melting process was prepared by melting, after grinding, polishing, and after a volume of 5% perchloric acid and 95% of the electrolytic etcheing solution prepared in ethanol corrosion observed after analysis of the microstructure and phase composition by XRD analysis .It can be found that Co-Al-W superalloys were mainly composed of cobalt-rich matrix of austenite precipitation of γ phase and coherent with matrix of the L12 structure of γ′-Co3(Al,W) phase. In addition, Nb have effect on grain refinement and refine grain. Rockwell hardness test and analysis, It can be found that Nb can clearly improve the Co-Al-W superalloy hardness.
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20

Jiang, Chao. "First-principles study of Co3(Al,W) alloys using special quasi-random structures." Scripta Materialia 59, no. 10 (November 2008): 1075–78. http://dx.doi.org/10.1016/j.scriptamat.2008.07.021.

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21

Chen, Min, and Chong-Yu Wang. "First-principle investigation of 3d transition metal elements in γ′-Co3(Al,W)." Journal of Applied Physics 107, no. 9 (May 2010): 093705. http://dx.doi.org/10.1063/1.3319650.

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22

Yao, Q., H. Xing, and J. Sun. "Structural stability and elastic property of the L12 ordered Co3(Al,W) precipitate." Applied Physics Letters 89, no. 16 (October 16, 2006): 161906. http://dx.doi.org/10.1063/1.2362574.

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23

Chen, Zhenghao M. T., Norihiko L. Okamoto, Masahiko Demura, and Haruyuki Inui. "Micropillar compression deformation of single crystals of Co3(Al,W) with the L12 structure." Scripta Materialia 121 (August 2016): 28–31. http://dx.doi.org/10.1016/j.scriptamat.2016.04.029.

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24

Kierat, Milena, and Maciej Liśkiewicz. "INFLUENCE OF 2% TITANIUM ADDITION ON MICROSCTRUCTURE AND SELECTED HIGH-TEMPERATURE PROPERTIES OF A NOVEL Co-BASED SUPERALLOY STRENGHTENED WITH L12 PHASE." Journal of Metallic Materials 73, no. 4 (June 7, 2022): 11–14. http://dx.doi.org/10.32730/imz.2657-747.21.4.2.

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This paper contains selected results of primary microsctructure analysis of a novel superalloy, Co-20Ni-10Al-5Mo-2Nb-2Ti. Research on this class of superalloys was started by J. Sato in 2006, and further expanded by S.K. Makineni in 2015. It is implied that Co-based, W-free superalloys will resolve the issues that the aircraft industry currently faces with Ni-based γ/γ’ superalloys. It is believed that the addition of the Ti alloying element will help with γ’ stabilisation due to high Co3(Mo, Al, Nb) fragmentation. Ti content has to be carefully selected to avoid precipitation of harmful phases, such as Co(Ti, Al).
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25

Kobayashi, Satoru, Yuki Tsukamoto, and Takayuki Takasugi. "The effects of alloying elements (Ta, Hf) on the thermodynamic stability of γ′-Co3(Al,W) phase." Intermetallics 31 (December 2012): 94–98. http://dx.doi.org/10.1016/j.intermet.2012.06.006.

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26

Xu, Weiwei, Yi Wang, Cuiping Wang, Xingjun Liu, and Zi-Kui Liu. "Alloying effects of Ta on the mechanical properties of γ’ Co3(Al, W): A first-principles study." Scripta Materialia 100 (April 2015): 5–8. http://dx.doi.org/10.1016/j.scriptamat.2014.11.029.

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27

Migas, Damian, Grzegorz Moskal, and Tomasz Maciąg. "Thermal analysis of W-free Co–(Ni)–Al–Mo–Nb superalloys." Journal of Thermal Analysis and Calorimetry 142, no. 1 (February 24, 2020): 149–56. http://dx.doi.org/10.1007/s10973-020-09375-7.

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Abstract In this investigation, the thermal analysis of W-free cobalt-based superalloys based on Co–Al–Mo–Nb and Co–Ni–Al–Mo–Nb systems was performed. The analysis was performed at different stages of heat treatment process. The differential thermal analysis (DTA) was utilized for the determination of characteristic temperatures related to microstructural changes. First of all, the DTA analysis was carried out for discussing as-cast alloys in the temperature range of 40–1500 °C. The results showed thermal effects connected with melting and important order–disorder transition. The temperature range of 1200–1250 °C was chosen for performance of a first heat treatment operation for the investigated alloys. Specimens were annealed at selected temperature for 5 h. The microstructure of alloys after solution heat treatment was analyzed as well. Afterward, the solutionized specimens were subjected to the further thermal analysis in order to select the aging temperature according to the order–disorder transformation related to formation of γ′ phase with overall formula Co3(Al,X). Five aging variants were performed in the temperature range of 800–1000 with a step of 50 °C. After each stage of heat treatment, SEM/EDS analysis and hardness measurements were performed.
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28

Kazantseva, N. V., D. I. Davydov, P. B. Terent’ev, D. A. Shishkin, S. L. Demakov, A. S. Yurovskikh, and E. P. Romanov. "Mechanical and magnetic properties of alloys near the concentration range of the existence of Co3(Al,W) intermetallic compound." Physics of Metals and Metallography 118, no. 5 (May 2017): 432–38. http://dx.doi.org/10.1134/s0031918x17050064.

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29

Xu, Weiwei, Yi Wang, Cuiping Wang, Xingjun Liu, and Zi-Kui Liu. "[P3] Effects of doping Ta on the ideal strength of γ’ Co3(Al, W) phase: A first principles study." Calphad 51 (December 2015): 372. http://dx.doi.org/10.1016/j.calphad.2015.01.093.

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30

Park, Seung Hwan C., Satoshi Hirano, Shinya Imano, Yutaka S. Sato, Hiroyuki Kokawa, Toshihiro Omori, and Kiyohito Ishida. "Friction-Stir Welding of High-Softening-Temperature Materials Using Cobalt-Based Alloy Tool." Materials Science Forum 706-709 (January 2012): 996–1001. http://dx.doi.org/10.4028/www.scientific.net/msf.706-709.996.

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The authors have developed a new friction-stir welding (FSW) tool that enables to weld high-softening-temperature materials (HSTMs), such as steels, titanium and zirconium alloys. The new tool is made of a Co-based heat-resistant alloy strengthened by precipitating intermetallics, Co3(Al,W), with a L12 structure at high temperatures. The Co-based alloy tool exhibits yield strengths higher than 500 MPa at 1000 deg C, so it might have a great potential as a tool material for FSW of HSTMs. In this study, the feasibility of using the Co-based alloy tool with various HSTMs was examined. Changes in the tool shape during FSW and the weld appearances produced with the Co-based alloy tool will be briefly shown.
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31

Zhong, F., Y. X. Yu, S. S. Li, and J. B. Sha. "In-situ SEM and TEM tensile observations of novel Co-Al-W-Mo-Ta-B-Ce alloys with a coherent γ-CoSS/γ’-Co3(Al,W) microstructure at room temperature." Materials Science and Engineering: A 696 (June 2017): 96–103. http://dx.doi.org/10.1016/j.msea.2017.04.040.

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32

Xu, W. W., J. J. Han, Y. Wang, C. P. Wang, X. J. Liu, and Z. K. Liu. "First-principles investigation of electronic, mechanical and thermodynamic properties of L12 ordered Co3(M, W) (M=Al, Ge, Ga) phases." Acta Materialia 61, no. 14 (August 2013): 5437–48. http://dx.doi.org/10.1016/j.actamat.2013.05.032.

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33

Jin, Min, Naihua Miao, Wenyue Zhao, Jian Zhou, Qiang Du, and Zhimei Sun. "Structural stability and mechanical properties of Co3(Al, M) (M = Ti, V, Cr, Zr, Nb, Mo, Hf, Ta, W) compounds." Computational Materials Science 148 (June 2018): 27–37. http://dx.doi.org/10.1016/j.commatsci.2018.02.015.

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34

Oomae, Mikio, Takeshi Teramoto, and Katsushi Tanaka. "Composition dependence of positive temperature dependence of yield stress for Co3(Al, W)–Co3Ti pseudo-binary alloy with the L12 structure." Intermetallics 136 (September 2021): 107250. http://dx.doi.org/10.1016/j.intermet.2021.107250.

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35

Mottura, Alessandro, Anderson Janotti, and Tresa M. Pollock. "A first-principles study of the effect of Ta on the superlattice intrinsic stacking fault energy of L12-Co3(Al,W)." Intermetallics 28 (September 2012): 138–43. http://dx.doi.org/10.1016/j.intermet.2012.04.020.

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36

Chen, Min, and Chong-Yu Wang. "First-principles investigation of the site preference and alloying effect of Mo, Ta and platinum group metals in γ′-Co3(Al,W)." Scripta Materialia 60, no. 8 (April 2009): 659–62. http://dx.doi.org/10.1016/j.scriptamat.2008.12.040.

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37

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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38

Liu, Xingjun, Yichun Wang, Wei-Wei Xu, Jiajia Han, and Cuiping Wang. "Effects of transition elements on the site preference, elastic properties and phase stability of L12 γ′-Co3(Al, W) from first-principles calculations." Journal of Alloys and Compounds 820 (April 2020): 153179. http://dx.doi.org/10.1016/j.jallcom.2019.153179.

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39

Zhang, Lanyue, Shan Di, Hong Lin, Chunmei Wang, Kai Yu, Jinghua Lv, Chunxiao Wang, and Baibin Zhou. "Nanomaterial with Core–Shell Structure Composed of {P2W18O62} and Cobalt Homobenzotrizoate for Supercapacitors and H2O2-Sensing Applications." Nanomaterials 13, no. 7 (March 25, 2023): 1176. http://dx.doi.org/10.3390/nano13071176.

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Designing and preparing dual-functional Dawson-type polyoxometalate-based metal–organic framework (POMOF) energy storage materials is challenging. Here, the Dawson-type POMOF nanomaterial with the molecular formula CoK4[P2W18O62]@Co3(btc)2 (abbreviated as {P2W18}@Co-BTC, H3btc = 1,3,5-benzylcarboxylic acid) was prepared using a solid-phase grinding method. XRD, SEM, TEM et al. analyses prove that this nanomaterial has a core–shell structure of Co-BTC wrapping around the {P2W18}. In the three-electrode system, it was found that {P2W18}@Co-BTC has the best supercapacitance performance, with a specific capacitance of 490.7 F g−1 (1 A g−1) and good stability, compared to nanomaterials synthesized with different feedstock ratios and two precursors. In the symmetrical double-electrode system, both the power density (800.00 W kg−1) and the energy density (11.36 Wh kg−1) are greater. In addition, as the electrode material for the H2O2 sensor, {P2W18}@Co-BTC also exhibits a better H2O2-sensing performance, such as a wide linear range (1.9 μM–1.67 mM), low detection limit (0.633 μM), high selectivity, stability (92.4%) and high recovery for the detection of H2O2 in human serum samples. This study provides a new strategy for the development of Dawson-type POMOF nanomaterial compounds.
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40

Tao, Zhuolin, Fei Zhong, Youxing Yu, and Jiangbo Sha. "Improvement of tensile behaviours of a γ'-Co3(Al, W) strengthened polycrystalline Co-9Al-4.5W-4.5Mo-2Ta-0.02B alloy at room-and high-temperatures by doping Ce." Progress in Natural Science: Materials International 29, no. 4 (August 2019): 416–24. http://dx.doi.org/10.1016/j.pnsc.2019.04.005.

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41

Pham Thi Ha, Thanh, Dung Nguyen Quoc, Phuong Le Thi, and Nhuong Vu Van. "Synthesis, characterization of Mg-Al-CO3 hydrotalcites modified by Cu2+ ions using as photocatalyst for degradation of methylene blue in water." Vietnam Journal of Catalysis and Adsorption 10, no. 1S (October 15, 2021): 252–58. http://dx.doi.org/10.51316/jca.2021.135.

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The CuMgAl hydrotalcite materials were synthesized by co-precipitation method using nitrate salts of Mg2+, Al3+, Cu2+ and Na2CO3 (Merck), at pH = 9.5, aged in a teflon flask at 100 oC for 24 hours. The synthesized materials were characterized by the following methods: XRD diagram, TEM image, EDS spectrum, the adsorption/desorption isotherm N2 (BET), UV-Vis DRS spectroscopy. The characterization results showed that the 8 synthesized samples have a double layered structure of hydrotalcite, the average particle sizes in the range of 15.09-21.20 nm and the absorption margin shifts strongly to the visible light region. The conversion of methylene blue (MB) increases when the ratio molars of ion Cu2+ in the samples arrange in 0 to 3.5, and set of the CuMgAl-2.5, CuMgAl-3.0 and Cu-MgAl-3.5 materials showed that they are able to degradate MB very well under visible light. The conversion of MB 30 ppm can reach 94 % after 90 min on CuMgAl-3.0 sample using irradiation of LED lamp 30 W light. The catalytic activity of the materials depends on the amount of Cu2+ in the sample, the concentration of H2O2, MB and the pH values of the medium.
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42

Chin, Zhenghao M. T., Norihiko L. Okamoto, and Haruyuki Inui. "Effects of Alloying Elements on the Temperature Dependence of Yield Stress in L12-Co3(Al,W)." MRS Proceedings 1760 (2015). http://dx.doi.org/10.1557/opl.2015.161.

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ABSTRACTThe effects of alloying elements (Ni/Ta) on the temperature dependence of yield stress in Co3(Al,W) with the L12 structure have been investigated through compression tests of nearly single-phase polycrystalline alloys in the temperature range between room temperature to 1,473K. Compared with a ternary Co3(Al,W), a Ni/Ta-added Co3(Al,W) alloy exhibits a higher γ΄ solvus temperature and lower onset temperature of the yield stress anomaly (positive temperature dependence of yield stress), suggesting that the CSF energy is increased by Ni/Ta addition. As a consequence, the high-temperature strength in Co3(Al,W) is considerably enhanced.
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43

Oohashi, Takashi, Norihiko L. Okamoto, Kyosuke Kishida, Katsushi Tanaka, and Haruyuki Inui. "Microstructures and Mechanical Properties of Co3(Al,W) with the L12 Structure." MRS Proceedings 1128 (2008). http://dx.doi.org/10.1557/proc-1128-u05-26.

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AbstractSince the ternary intermetallic compound Co3(Al,W) with the L12 structure was discovered, two-phase Co-base alloys composed of the γ-Co solid-solution phase and the γ'-Co3(Al,W) phase as a strengthening phase have been investigated as promising high-temperature materials. Some Co-base alloys have been reported to exhibit high-temperature strength greater than those of conventional Ni-base superalloys. Although the excellent high-temperature physical properties of the Co-based alloys are considered to result from the phase stability and strength of Co3(Al,W), the pristine physical properties of Co3(Al,W) have not been fully understood, supposedly due to the difficulties in obtaining single-phase Co3(Al,W). In the present study, we examine the effect of heat treatment on the microstructure of alloys with compositions close to single-phase Co3(Al,W) as well as their mechanical properties, e.g. elastic modulus, thermal expansion, etc., in hope of deriving the pristine properties of the Co3(Al,W) phase. A single crystal with the composition of Co-10Al-11W grown by floating-zone melting exhibits a thermal expansion coefficient of 10×10-6 K-1 at room temperature, which is virtually identical to those of the commercial Ni-base superalloys. However, it increases with increasing temperature followed by a discontinuity at around 1000°C, inferring the phase transformation from γ' to γ. The investigated thermal expansion behavior indicates that the lattice mismatch between the γ' and γ phases is reversed from positive at room temperature to negative at high temperatures above around 500°C. The results of elastic property measurement and environmental embrittlement investigation of polycrystalline Co3(Al,W) will also be presented.
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44

Inui, Haruyuki, Katsushi Tanaka, Kyosuke Kishida, Norihiko L. Okamoto, and Takashi Oohashi. "Physical and Mechanical Properties of Single Crystals of Co-Al-W Based Alloys with L12 Single-Phase and L12/fcc Two-Phase Microstructures." MRS Proceedings 1128 (2008). http://dx.doi.org/10.1557/proc-1128-u06-07.

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AbstractSingle-crystal elastic constants of Co3(Al,W) with the cubic L12 structure have been experimentally measured by resonance ultrasound spectroscopy at liquid helium temperature. The values of all the three independent single-crystal elastic constants and polycrystalline elastic constants of Co3(Al,W) experimentally determined are 15~25% larger than those of Ni3(Al,Ta) but are considerably smaller than those previously reported. Two-phase microstructures with cuboidal L12 precipitates being well aligned parallel to <100> and well faceted parallel to {100} are expected to form very easily in Co-base superalloys because of the large value of E111/E100 and cij of Co3(Al,W). This is indeed confirmed by experiment. Values of yield stress obtained for both [001] and [¯123] orientations of L12/fcc two-phase single crystals moderately decrease with the increase in temperature up to 800°C and then decrease rapidly with temperature above 800°C without any anomaly in yield stress. Slip on {111} is observed to occur for both orientations in the whole temperature range investigated.
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45

Ishida, Kiyohito. "Intermetallic Compounds in Co-base Alloys–Phase Stability and Application to Superalloys." MRS Proceedings 1128 (2008). http://dx.doi.org/10.1557/proc-1128-u06-06.

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AbstractThe phase stability of intermetallic compounds of Co3X has been discussed with a focus on the γ' phase of Co3Al, Co3W and Co3(Al, W) with the L12 structure. The critical temperatures of the γ' phase of Co3Al, Co3W and Co3(Al, W) compounds are estimated to be about 870 , 980 and 1076 , respectively. The effect of alloying elements on the Co-Al-W -base alloys was found to be very similar to that of Ni-base superalloys, where Ti, Ta, Nb and V are the γ' stabilizing elements, while Mn, Fe and Cr are the γ' forming elements. The mechanical properties of Co-Al-W-base alloys were also found to be similar to those of Ni-base alloys. In particular, the flow strengths of Co-Al-W-base alloys at temperatures above 800 were comparable or higher than those of Ni-base superalloys, which implies that the Co-base superalloys strengthened by the γ' phase have great potential as a new type of high-temperature alloys.
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46

Tsukamoto, Yuki, Satoru Kobayashi, and Takayuki Takasugi. "Alloying Effects on the Stability of γ/γ′ Microstructure in Co-Al-W Base Alloys." MRS Proceedings 1295 (2011). http://dx.doi.org/10.1557/opl.2011.313.

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ABSTRACTThe aim of this study is two-fold: first we reexamine the thermodynamic stability of γ’-Co3(Al,W) phase in the Co-Al-W ternary system. Secondly, we investigate the effect of a fourth alloying element (Ti or Ta) on the thermodynamic stability of the γ’ phase through microstructure observation, DSC measurement and EPMA analysis. Coarsened areas with γ/CoAl/Co3W phases are formed after annealing at 900 ºC for 2000 h in Co-Al-W ternary alloys with different Al/W ratios, which confirms that the three phases are in equilibrium with each other and that the γ’ phase is metastable at this temperature. The addition of a fourth alloying elements does not drastically change the microstructure formed after long term annealing at 900 ºC, indicating that the alloying elements do not improve the stability of the γ’ phase.
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47

Pyczak, F., Z. Liang, S. Neumeier, and Z. Rao. "Stability and Physical Properties of the L12-γ′ Phase in the CoNiAlTi-System." Metallurgical and Materials Transactions A, January 22, 2023. http://dx.doi.org/10.1007/s11661-022-06949-y.

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AbstractThere is a current interest in Co-based superalloys hardened by a L12-γ′ phase because Co has a higher melting point than Ni and is more resistant against sulfidation attack. However, the Co-Al-W system many of those γ′ hardened Co-based superalloys are based on, has a number of drawbacks. The γ′ phase Co3(Al,W) is not stable at high temperature, the density of the alloys is very high and the oxidation resistance is insufficient. Due to this, there is an ongoing interest to develop γ′-hardened Co-based superalloys based on other systems. Here, first principles calculations are presented to investigate the properties of the γ′ L12-(Co0.5,Ni0.5)3(Al0.5,Ti0.5) phase and related L12 structures. (Co0.5,Ni0.5)3(Al0.5,Ti0.5) exhibits a lower energy of formation than Co3Ti and Co3(Al0.5,W0.5). Nevertheless, Ni3(Al0.5,Ti0.5) has an even lower energy of formation which is further lowered if Ti is enriched on the second sublattice. This finding is supported by analyzing the electronic densities of states. Ni3(Al0.5,Ti0.5) and especially Ni3(Al0.25,Ti0.75) exhibit Fermi levels close to the gap between binding and antibinding states, which is an indicator for stability. In addition to the stability of the γ′-phase in dependence on Ni and Ti content, also the elastic properties were calculated. Ni3(Al0.25,Ti0.75) is less elastic anisotropic and has higher Young’s and shear modulus compared to Ni3(Al0.5,Ti0.5) and (Co0.5,Ni0.5)3(Al0.5,Ti0.5).
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48

Suzuki, Akane, Garret C. DeNolf, and Tresa M. Pollock. "High Temperature Strength of Co-based γ/γ' Superalloys." MRS Proceedings 980 (2006). http://dx.doi.org/10.1557/proc-980-0980-ii08-09.

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AbstractThe high temperature strength of new Co-Al-W based alloys consisting of a ?-Co (fcc) matrix phase and a high volume fraction of ?'-Co3(Al, W) ternary L12 intermetallic compound has been examined in order to understand the strengthening mechanisms and to explore the possibility for high temperature applications. The flow stress exhibits a strong, positive dependence on temperature above 873 K. Additions of Ta improve the high temperature strength, and the strength of a Ta containing alloy is comparable to Ni-base superalloys at 1173 K. Transmission microscopy on the deformed Ta containing alloy revealed that the active slip modes within the ?' precipitates are <110>{111} and <112>{111} below and above the peak temperature, respectively. At the peak flow temperature, multiple slip modes including <110>{111}, <110>{001} and <112>{111} were observed.
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49

Chen, Zhenghao, Kyosuke Kishida, Haruyuki Inui, Martin Heilmaier, Uwe Glatzel, and Gunther Eggeler. "Improving the intermediate- and high-temperature strength of L12-Co3(Al,W) by Ni and Ta additions." Acta Materialia, July 2022, 118224. http://dx.doi.org/10.1016/j.actamat.2022.118224.

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50

Wolf, Maximilian, Christian Edtmaier, and Raquel de Oro Calderon. "Influence of carbon on the formation of γ/γ′ microstructure and κ-phase in the WC/Co–Ni–Al–W system: ab initio calculations and experimental studies." Journal of Materials Science, July 15, 2022. http://dx.doi.org/10.1007/s10853-022-07493-1.

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AbstractModifications of the binder phase (γ) of cemented carbides have the potential to increase the hardness and wear resistance of the whole material. Partially, coherent precipitations with L12 structure (γ’) promise these improved properties without sacrificing tensile strength or toughness. γ’ is a metastable phase in the Al–Co–W ternary system in the form of Co3(Al,W) which is stabilized by the substitution of cobalt with nickel. Superalloys of the composition Co–(30Ni)–9Al–7 W with different carbon contents were prepared by inductive melting, and the resulting microstructures were analysed using SEM–EDS, XRD and Vickers hardness. Cemented carbides with γ/γ’ binder microstructure were prepared via DTA, and the phase equilibria in the composite material were investigated experimentally and in silico. It was shown that nickel stabilizes the γ’ phase in superalloys as well as in cemented carbides. Carbon leads to the formation of an additional phase with E21 structure (κ). DTA measurements of cemented carbides with different aluminium–cobalt–nickel mixtures as binder gave an overview of the compositional influence. Enthalpies of formation for compounds with L12 and E21 structure were calculated using ab initio methods and compared to experimental results. Graphical Abstract
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