scholarly journals Morphology and microstructure of annealed Ni-Co alloy powders electrodeposited on copper substrates

2009 ◽  
Vol 41 (2) ◽  
pp. 135-142 ◽  
Author(s):  
L.D. Rafailovic ◽  
A.M. Maricic ◽  
W. Artner ◽  
G.E. Nauer ◽  
D.M. Minic
Keyword(s):  
Current Density ◽  
Structural Changes ◽  
Sulfate Solution ◽  
Face Centered Cubic ◽  
Bath Composition ◽  
X Ray Diffraction ◽  
Hexagonal Close Packed ◽  
Galvanostatic Regime ◽  
Face Centered ◽  
Deposition Current Density

Nickel and cobalt alloy powders from two different electrolyte compositions were obtained by electrodeposition from an ammonium sulfate solution. The structure of Ni-Co deposits formed by electrodeposition at a galvanostatic regime and the influence of current density and the bath composition were studied by SEM, DSC and X-ray diffraction methods. It was shown that the microstructure and morphology of the powders depended on the deposition current density as well as bath composition. Both, bath composition and current density affect strongly the deposit growth mechanism and the deposit composition, microstructure, grain size and surface morphology. It was found that the overpotential significantly affects the structure of the formed deposits. When electrodeposition was performed far from equilibrium conditions face-centered cubic (FCC) cobalt was deposited while at low overpotential hexagonal close packed (HCP) Co was formed with a lower rate of hydrogen evolution. The increase of HCP phase in the nanocrystalline deposits was caused by increase of the Co content in the powder as well by decrease of the deposition current density. It was shown that the powders change their structure in the temperature interval from 300?C to 600?C. In Co rich samples, structural changes during heating were attributed to the phase transformation of HCP to FCC.

Synthesis and Characterization of Cobalt-Nickel Nanowires Formed under External Magnetic Field

2015 ◽  
Vol 799-800 ◽  
pp. 120-124 ◽  
Author(s):  
Mary Donnabelle L. Balela ◽  
Lalaine M. Dulin ◽  
Erica A. Garcia ◽  
M. Janelle H. Tica
Keyword(s):  
Magnetic Field ◽  
External Magnetic Field ◽  
Face Centered Cubic ◽  
X Ray Diffraction ◽  
X Ray ◽  
Hexagonal Close Packed ◽  
Cobalt Nickel ◽  
Nickel Nanowires ◽  
Face Centered

Cobalt-nickel (Co-Ni) nanowires were formed by electroless deposition in ethylene glycol under external magnetic field. The effects of initial Co (II) and Ni (II) concentration on the surface and morphology of the synthesized nanowires were investigated by x-ray diffraction (XRD) and scanning electron microscope (SEM) respectively. An increase in the Co (II) concentration resulted in increase in diameter of the nanowires. However, the length of nanowires was observed to decrease. Higher Co (II) concentration resulted in a mixture of hexagonal close-packed and face-centered cubic Co-Ni nanowires. X-ray diffraction revealed that crystal growth occurred when the nanowires are annealed at 653 K for 10h.

Preparation of Co3Ni Film Composed of Nanosheets and their Catalytic Activity in Hydrogen Generation from Sodium Borohydride Solution

2013 ◽  
Vol 860-863 ◽  
pp. 822-825
Author(s):  
Jin Yun Liao ◽  
Hao Li ◽  
Xi Bin Zhang
Keyword(s):  
Catalytic Activity ◽  
High Performance ◽  
Hydrogen Generation ◽  
Deposition Process ◽  
Cubic Phase ◽  
Face Centered Cubic ◽  
X Ray Diffraction ◽  
Original Activity ◽  
Hexagonal Close Packed ◽  
Face Centered

In this study, aiming to obtain high performance nanocatalysts for NaBH4 hydrolysis, Co3Ni film composed of nanosheets with a mean thickness of 10 nm was fabricated by a magnetic field induced deposition process. X-ray diffraction analysis indicated that the as-prepared Co3Ni film is presented in both face-centered cubic phase and hexagonal close-packed phase. The nanostructured Co3Ni film catalyst showed good catalytic activity in the hydrolysis of NaBH4 and the rate constant was 5.77 mL·min-1. It was revealed that Co3Ni film catalysts didnt lose their catalytic original activity essentially after 10 cycles, which exhibited much improved reusability and stability compared with with recently reported nanocatalysts.

High-precision face-centered cubic–hexagonal close-packed volume-change determination in high-Mn steels by X-ray diffraction data refinements

2020 ◽  
Vol 53 (1) ◽  
pp. 34-44 ◽  
Author(s):  
Florencia Malamud ◽  
Facundo Castro ◽  
Lina Maria Guerrero ◽  
Paulo La Roca ◽  
Marcos Sade ◽  
...  
Keyword(s):  
High Precision ◽  
Volume Change ◽  
Low Cycle Fatigue ◽  
Damping Capacity ◽  
Powder Materials ◽  
Face Centered Cubic ◽  
X Ray Diffraction ◽  
X Ray ◽  
Hexagonal Close Packed ◽  
Face Centered

High-Mn steels attract attention because of their various technological properties. These are mainly mechanical and functional, such as the shape-memory effect, high damping capacity, high strength with simultaneous large ductility, the TRIP/TWIP (transformation- and twinning-induced plasticity) effect, low cycle fatigue and high work hardening capacity. All these phenomena are associated with the face-centered cubic (f.c.c.)–hexagonal close-packed (h.c.p.) martensitic transformation which takes place in these alloys. During this phase transition defects are introduced, mainly due to the large volume change between austenite and martensite. Knowing this volume change is key to understanding the mechanical behavior of these metallic systems. In the present article, a full-pattern refinement method is presented. The proposed method uses data obtained by means of conventional X-ray diffraction from regular bulk samples and allows a high-precision calculation of the lattice parameters of both phases, f.c.c. and h.c.p., under conditions very different from randomly oriented (powder) materials. In this work, the method is used to study the effect of chemical composition on the volume change between the two structures. By applying empirical models, the results enabled the design and fabrication of Fe–Mn-based alloys with a small volume change, showing the potential of this new tool in the search for improved materials.

Depletion of Manganese in the Surface Layers of Fe-Mn-Si Shape Memory Alloys by Annealing

2015 ◽  
Vol 363 ◽  
pp. 196-201
Author(s):  
Yusuke Onuki ◽  
Shun Fujieda ◽  
Kozo Shinoda ◽  
Hiroshi Ohtani ◽  
Tadakatsu Maruyama ◽  
...  
Keyword(s):  
Surface Layer ◽  
Shape Memory Alloys ◽  
Shape Memory ◽  
Face Centered Cubic ◽  
X Ray Diffraction ◽  
Surface Layers ◽  
Hexagonal Close Packed ◽  
Compositional Changes ◽  
Face Centered ◽  
The Stability

X-ray diffraction (XRD) and electron microprobe microanalysis (EPMA) were used for characterizing the structure and composition of surface layers formed on austenitic Fe-Mn-Si shape memory alloys under vacuum. The XRD results demonstrated that during annealing, face centered cubic austenite is transformed to hexagonal close packed martensite on the alloy surface. The EMPA results revealed that manganese in the surface layer was depleted during annealing. Further, this analysis determined that the thickness of the surface layer of the alloy annealed at 1173 K for 1 h was approximately 20 μm and that value is consistent with the depth detected by XRD. The compositional changes of the surface layers such as manganese depletion by annealing were discussed based on the ternary Fe-Mn-Si phase diagram. Although the formation of body centered cubic ferrite is detrimental to shape memory alloys, the amount of manganese was also observed to change during processing and strongly influence the stability of the shape memory alloys.

Diffraction Stress Analysis of Fiber Textured Ti Thin Films Undergoing hcp - fcc Phase Transformation

2013 ◽  
Vol 768-769 ◽  
pp. 257-263
Author(s):  
Jay Chakraborty
Keyword(s):  
Thin Films ◽  
Phase Transformation ◽  
Stress Analysis ◽  
Group Method ◽  
Face Centered Cubic ◽  
X Ray Diffraction ◽  
Hexagonal Close Packed ◽  
Face Centered ◽  
Fcc Phase ◽  
Ti Films

X-ray diffraction stress analysis by crystallite group method (CGM) has been employed in case of simultaneously strong and sharp fiber textured Ti thin films. These Ti films exhibit thickness dependent hcp-fcc phase transformation [Ref. 1]. Diffraction stress analysis has also been attempted by d-sin2 method for strongly textured face centered cubic (fcc) and hexagonal close packed (hcp) Ti phases. For hcp Ti phase, the results of stress analysis by CGM are compared with those obtained from d-sin2 method. It is found that the stress values in hcp Ti phases obtained from CGM considerably differ from the stresses obtained from d-sin2 method in some of the Ti films. Observed differences have been explained and possible sources of errors in d-sin2 method and CGM stress analysis have been discussed.

Microstructure of Electro-Eroded Cemented Carbide Surfaces

1968 ◽  
Vol 26 ◽  
pp. 284-285
Author(s):  
V. N. Filimonenko ◽  
M. H. Richman ◽  
J. Gurland
Keyword(s):  
Surface Layer ◽  
Cobalt Content ◽  
Cemented Carbides ◽  
Face Centered Cubic ◽  
X Ray Diffraction ◽  
Metallographic Examination ◽  
Standard Procedures ◽  
Face Centered ◽  
Diamond Paste ◽  
Plastic Carbon

The high temperatures and pressures that are found in a spark gap during electrical discharging lead to a sharp phase transition and structural transformation in the surface layer of cemented carbides containing WC and cobalt. By means of X-ray diffraction both W2C and a high-temperature monocarbide of tungsten (face-centered cubic) were detected after electro-erosion. The W2C forms as a result of the peritectic reaction, WC → W2C+C. The existence and amount of the phases depend on both the energy of the electro-spark discharge and the cobalt content. In the case of a low-energy discharge (i.e. C=0.01μF, V = 300v), WC(f.c.c.) is generally formed in the surface layer. However, at high energies, (e.g. C=30μF, V = 300v), W2C is formed at the surface in preference to the monocarbide. The phase transformations in the surface layer are retarded by the presence of larger percentages of cobalt.Metallographic examination of the electro-eroded surfaces of cemented carbides was carried out on samples with 5-30% cobalt content. The specimens were first metallographically polished using diamond paste and standard procedures and then subjected to various electrical discharges on a Servomet spark machining device. The samples were then repolished and etched in a 3% NH4OH electrolyte at -0.5 amp/cm2. Two stage plastic-carbon replicas were then made and shadowed with chromium at 27°.

scholarly journals Stability and equation of state of face-centered cubic and hexagonal close packed phases of argon under pressure

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Agnès Dewaele ◽  
Angelika D. Rosa ◽  
Nicolas Guignot ◽  
Denis Andrault ◽  
João Elias F. S. Rodrigues ◽  
...  
Keyword(s):  
Equation Of State ◽  
Single Crystal ◽  
Single Crystal Sample ◽  
Moderate Pressure ◽  
Face Centered Cubic ◽  
Experimental Conditions ◽  
Crystal Sample ◽  
Hexagonal Close Packed ◽  
Face Centered ◽  
Fcc Phase

AbstractThe compression of argon is measured between 10 K and 296 K up to 20 GPa and and up to 114 GPa at 296 K in diamond anvil cells. Three samples conditioning are used: (1) single crystal sample directly compressed between the anvils, (2) powder sample directly compressed between the anvils, (3) single crystal sample compressed in a pressure medium. A partial transformation of the face-centered cubic (fcc) phase to a hexagonal close-packed (hcp) structure is observed above 4.2–13 GPa. Hcp phase forms through stacking faults in fcc-Ar and its amount depends on pressurizing conditions and starting fcc-Ar microstructure. The quasi-hydrostatic equation of state of the fcc phase is well described by a quasi-harmonic Mie–Grüneisen–Debye formalism, with the following 0 K parameters for Rydberg-Vinet equation: $$V_0$$ V 0 = 38.0 Å$$^3$$ 3 /at, $$K_0$$ K 0 = 2.65 GPa, $$K'_0$$ K 0 ′ = 7.423. Under the current experimental conditions, non-hydrostaticity affects measured P–V points mostly at moderate pressure ($$\le$$ ≤ 20 GPa).

scholarly journals Microstructure Refinement by Low-Temperature Ausforming in an Fe-Based Metastable High-Entropy Alloy

Metals ◽  
2021 ◽  
Vol 11 (5) ◽  
pp. 742
Author(s):  
Motomichi Koyama ◽  
Takeaki Gondo ◽  
Kaneaki Tsuzaki
Keyword(s):  
Low Temperature ◽  
Plastic Anisotropy ◽  
High Entropy Alloy ◽  
Face Centered Cubic ◽  
High Entropy ◽  
Microstructure Refinement ◽  
Hexagonal Close Packed ◽  
Solution Treated Condition ◽  
Solution Treated ◽  
Face Centered

The effects of ausforming in an Fe30Mn10Cr10Co high-entropy alloy on the microstructure, hardness, and plastic anisotropy were investigated. The alloy showed a dual-phase microstructure consisting of face-centered cubic (FCC) austenite and hexagonal close-packed (HCP) martensite in the as-solution-treated condition, and the finish temperature for the reverse transformation was below 200 °C. Therefore, low-temperature ausforming at 200 °C was achieved, which resulted in microstructure refinement and significantly increased the hardness. Furthermore, plasticity anisotropy, a common problem in HCP structures, was suppressed by the ausforming treatment. This, in turn, reduced the scatter of the hardness.

Observation of the Formation Processes of Hexagonal Close-packed and Face-centered Cubic Ru Nanoparticles

2019 ◽  
Vol 48 (9) ◽  
pp. 1062-1064 ◽  
Author(s):  
Naoki Araki ◽  
Kohei Kusada ◽  
Satoru Yoshioka ◽  
Takeharu Sugiyama ◽  
Toshiaki Ina ◽  
...  
Keyword(s):  
Face Centered Cubic ◽  
Formation Processes ◽  
Hexagonal Close Packed ◽  
Ru Nanoparticles ◽  
Face Centered

Stacking Faults in a High Nitrogen Face-Centered-Cubic Phase Formed on Nitrogen-Modified Austenitic Stainless Steel

2008 ◽  
Vol 373-374 ◽  
pp. 318-321
Author(s):  
J. Liang ◽  
M.K. Lei
Keyword(s):  
Stainless Steel ◽  
Plasma Source ◽  
Peak Shift ◽  
Cubic Phase ◽  
Face Centered Cubic ◽  
X Ray Diffraction ◽  
High Nitrogen ◽  
X Ray ◽  
Peak Asymmetry ◽  
Face Centered

Effects of stacking faults in a high nitrogen face-centered-cubic phase (γΝ) formed on plasma source ion nitrided 1Cr18Ni9Ti (18-8 type) austenitic stainless steel on peak shift and peak asymmetry of x-ray diffraction were investigated based on Warren’s theory and Wagner’s method, respectively. The peak shift from peak position of the γΝ phase is ascribed to the deformation faults density α, while the peak asymmetry of the γΝ phase is characterized by deviation of the center of gravity of a peak from the peak maximum (Δ C.G.) due to the twin faults density β. The calculated peak positions of x-ray diffraction patterns are consistent with that measured for plasma source ion nitrided 1Cr18Ni9Ti stainless steel.

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