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J R Vargasgarcia - One of the best experts on this subject based on the ideXlab platform.

  • oxygen reduction reaction on cobalt nickel Alloys prepared by mechanical alloying
    Journal of Alloys and Compounds, 2007
    Co-Authors: M A Garciacontreras, S M Fernandezvalverde, J R Vargasgarcia
    Abstract:

    Abstract Mechanical alloying technique was used to prepare several Co–Ni Alloys in a high-energy SPEX 8000 mill. The initial ratios of elemental Co–Ni powders were 30:70, 40:60, 50:50, 60:40 and 70:30 wt.%. Elemental cobalt and nickel powders were milled separately during 20 h as a reference. XRD results indicated that crystalline solid solutions were achieved after 5 h of milling. TEM observations revealed that mechanical Alloys consist of agglomerated fine particles of about 10 nm in size. Electrochemical measurements showed that the Co–Ni 30:70 wt.%, in particular, exhibited the highest current density for the oxygen reduction reaction (ORR) via four electrons.

M A Garciacontreras - One of the best experts on this subject based on the ideXlab platform.

  • oxygen reduction reaction on cobalt nickel Alloys prepared by mechanical alloying
    Journal of Alloys and Compounds, 2007
    Co-Authors: M A Garciacontreras, S M Fernandezvalverde, J R Vargasgarcia
    Abstract:

    Abstract Mechanical alloying technique was used to prepare several Co–Ni Alloys in a high-energy SPEX 8000 mill. The initial ratios of elemental Co–Ni powders were 30:70, 40:60, 50:50, 60:40 and 70:30 wt.%. Elemental cobalt and nickel powders were milled separately during 20 h as a reference. XRD results indicated that crystalline solid solutions were achieved after 5 h of milling. TEM observations revealed that mechanical Alloys consist of agglomerated fine particles of about 10 nm in size. Electrochemical measurements showed that the Co–Ni 30:70 wt.%, in particular, exhibited the highest current density for the oxygen reduction reaction (ORR) via four electrons.

S M Fernandezvalverde - One of the best experts on this subject based on the ideXlab platform.

  • oxygen reduction reaction on cobalt nickel Alloys prepared by mechanical alloying
    Journal of Alloys and Compounds, 2007
    Co-Authors: M A Garciacontreras, S M Fernandezvalverde, J R Vargasgarcia
    Abstract:

    Abstract Mechanical alloying technique was used to prepare several Co–Ni Alloys in a high-energy SPEX 8000 mill. The initial ratios of elemental Co–Ni powders were 30:70, 40:60, 50:50, 60:40 and 70:30 wt.%. Elemental cobalt and nickel powders were milled separately during 20 h as a reference. XRD results indicated that crystalline solid solutions were achieved after 5 h of milling. TEM observations revealed that mechanical Alloys consist of agglomerated fine particles of about 10 nm in size. Electrochemical measurements showed that the Co–Ni 30:70 wt.%, in particular, exhibited the highest current density for the oxygen reduction reaction (ORR) via four electrons.

Wei Wang - One of the best experts on this subject based on the ideXlab platform.

  • high speed jet electrodeposition and microstructure of nanocrystalline ni co Alloys
    Electrochimica Acta, 2005
    Co-Authors: Guiying Qiao, Tianfu Jing, Nan Wang, Yuwei Gao, Xin Zhao, Jifeng Zhou, Wei Wang
    Abstract:

    Abstract The jet electrodeposition from watts baths with a device of electrolyte jet was carried out to prepare nano-crystalline cobalt–nickel Alloys. The influence of the concentration of Co 2+ ions in the electrolyte and electrolysis parameters, such as the cathodic current density, the temperature as well as the electrolyte jet speed, on the chemistry and microstructure of Ni–Co-deposit Alloys were investigated. Experimental results indicated that increasing the Co 2+ ions concentration in the bath, the electrolyte jet speed and decreasing of the cathodic current density and decrease of the electrolyte temperature all results in an increase of cobalt content in the alloy. Detailed microstructure changes upon the changes of alloy composition and experimental conditions were characterized using X-ray diffraction (XRD) and transmission electron microscopy (TEM). XRD results show the Ni–Co solid solution was formed through the jet electrodeposition. Phase constitution of solid solution changes progressively under different electrolyte concentration. Alloys with low Co concentration exhibit single phase of face-centered cubic (fcc) structure; The Co concentration over 60.39 wt.%, the Alloys are composed of face-centered cubic (fcc) phase and hexagonal close-packed (hcp) phase. Furthermore, the formation of the nanostructured Ni–Co alloy deposit is investigated. Increasing the Co 2+ ions concentration in the bath, the cathodic current density, the electrolyte temperature and the electrolyte jet speed all result in the finer grains in the deposits. Additives such as saccharin in the electrolyte also favor the formation of the finer grains in the alloy deposits.

Rathi Anuj - One of the best experts on this subject based on the ideXlab platform.

  • Synthesis Of High-Entropy-Alloy-Based Magnetic Alloys By Mechanical Alloying
    2018
    Co-Authors: Rathi Anuj
    Abstract:

    The objective of this thesis work was to synthesize high-entropy based magnetic Alloys and investigate the phase evolution during the synthesis and thermal treatments. A thorough literature review was performed on magnetic high-entropy Alloys. The ternary iron-Cobalt-Nickel Alloys (Fe33.33Co33.33Ni33.33, Ni40Co30Fe30, Fe40Co30Ni30, Co40Fe30Ni30, and Fe46Co34 Ni20) and the quaternary iron-Cobalt-Nickel-silicon Alloys (Fe40Co30Ni30)0.9Si0.1 were synthesized by mechanical alloying, followed by structural characterization of phase evolution by x-ray diffraction (XRD), scanning electron microscopy (SEM) and magnetic characterization by magnetometry. The Fe33.33Co33.33Ni33.33 alloy was formed after mechanical alloying for ~9 hours. The lattice parameter of the face-centered-cubic (f.c.c) alloy was ~0.3591 nm and the crystallite size was ~12 nm. The SEM revealed particle size (D90) ~15.9 µm. The alloy exhibited decent magnetic properties having saturation magnetization (MS) of ~136 ± 3 Am2/kg and coercivity (HC) of ~2.4 kA/m at room temperature. After the thermal treatment, Ms increased by ~14% and Hc decreased by 60%. Among the Ni40Co30Fe30, Fe40Co30Ni30, and Co40Fe30Ni30 Alloys, the Fe-rich alloy mechanically alloyed for 12 hours showed superior magnetic properties. The Ms was ~148 ± 3 Am2/kg and the Hc was ~4.3 kA/m. The lattice parameter, crystallite size, and D90 was ~0.3574 nm, ~8 nm, and ~5.5 µm, respectively. Thermal treatment of the Fe-rich alloy improved its magnetic properties. It increased Ms by 10% and decreased Hc by 25%. The Fe46Co34 Ni20 showed the best magnetic properties among all, the Ms was ~167 ± 2 Am2/kg and the Hc was ~3.3 kA/m. Lastly, in the case of (Fe40Co30Ni30)0.9Si0.1 alloy, the Ms decreased by ~10% and the Hc increased by ~40% compared to Fe40Co30Ni30 alloy. A systematic study of magnetic properties of the iron-Cobalt-Nickel Alloys is likely to provide the necessary foundation for the development of high-entropy based magnetic Alloys by further alloying additions.Master of Science in EngineeringMechanical Engineering, College of Engineering & Computer ScienceUniversity of Michigan-Dearbornhttps://deepblue.lib.umich.edu/bitstream/2027.42/145479/1/49698122_20180711_anuj_rathi_thesis_embedded.pdfDescription of 49698122_20180711_anuj_rathi_thesis_embedded.pdf : Thesi