The Ni-Al-Hf Multiphase Diffusion

Abstract The generalized Darken method was applied to simulate the diffusion between γ-Ni| γ’-Ni3Al and γ’-Ni3Al|β-NiAl interfaces. The results of calculations were compared with the experimental concentration’s profiles of nickel, aluminum and hafnium in aluminide and hafnium doped aluminide coatings deposited by the CVD and PVD methods on pure nickel. The method deals with the Wagner’s integral diffusion coefficients and thermodynamic data - activities of components. The experimental results agree with the simulated ones.

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The Ni-Al-Zr Multiphase Diffusion Simulations

High Temperature Materials and Processes ◽

10.1515/htmp-2014-0080 ◽

2015 ◽

Vol 34 (5) ◽

Cited By ~ 2

Author(s):

Bartek Wierzba ◽

Jolanta Romanowska ◽

Maryana Zagula-Yavorska ◽

Janusz Markowski ◽

Jan Sieniawski

Keyword(s):

Mass Transport ◽

Diffusion Zone ◽

Quantitative Description ◽

Pure Nickel ◽

Phase Volume ◽

Volume Fractions ◽

Aluminide Coatings ◽

Multiphase Diffusion ◽

Multi Phase ◽

Diffusion Mass

AbstractThe generalized Darken method allows a quantitative description of diffusion mass transport in multi-phase materials. The method characterizes the diffusion zone by phase volume fractions. The results of the calculations are compared with experimental concentration’s profiles of nickel, zirconium and aluminum in zirconium doped aluminide coatings deposited on pure nickel by the PVD and CVD methods.

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Stability of As and B doped Si with respect to overlaying CoSi2 and TiSi2 thin films

Journal of Materials Research ◽

10.1557/jmr.1989.1209 ◽

1989 ◽

Vol 4 (5) ◽

pp. 1209-1217 ◽

Cited By ~ 62

Author(s):

K. Maex ◽

G. Ghosh ◽

L. Delaey ◽

V. Probst ◽

P. Lippens ◽

...

Keyword(s):

Thin Film ◽

Thin Films ◽

Phase Diagrams ◽

Thermodynamic Data ◽

Ternary Phase ◽

Experimental Results ◽

Silicide Formation ◽

Isothermal Sections ◽

Ternary Phase Diagrams ◽

The Stability

The thermodynamic equilibrium of structures consisting of a thin film silicide (TiSi2 or CoSi2) on doped Si (with As or B) is investigated. Isothermal sections of the ternary phase diagrams for Ti–Si–B, Co–Si–B, Ti–Si–As, and Co–Si–As have been evaluated, indicating the stability of high B concentrations in Si underneath a CoSi2 layer, the instability of high As concentrations in Si underneath a CoSi2 layer, and of B and As concentrations underneath a TiSi2 layer. The obtained thermodynamic predictions agree very well with experimental results (i) on the redistribution of dopants during silicide formation, (ii) on the diffusion of dopants from an ion implanted silicide, and (iii) on the stability of highly doped regions underneath the silicide, both for the case of TiSi2 and CoSi2. It is shown that even though the inaccuracy of reported thermodynamic data is substantial, thermodynamic calculations provide a useful guidance and are consistent with the experimental results.

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Chemistry of rhenium as an analogue of technetium: Experimental studies of the dissolution of rhenium oxides in aqueous solutions

Radiochimica Acta ◽

10.1524/ract.91.4.211.19968 ◽

2003 ◽

Vol 91 (4) ◽

Cited By ~ 25

Author(s):

E. Kim ◽

J. Boulègue

Keyword(s):

Aqueous Solutions ◽

Thermodynamic Data ◽

Experimental Studies ◽

Experimental Results ◽

Radioactive Element ◽

Oxidation States ◽

Dissolution Behavior ◽

High Concentration ◽

Very High ◽

Chemical Analogue

SummaryThe migration of fissiogenic Tc into the environment can be predicted by studying the dissolution behavior of Re, a chemical analogue of Tc, avoiding the use of a radioactive element at high concentration. We developed a series of experimental studies of the solubility of Re oxides under various oxidation states (+VII, +IV, and +III), in oxidizing and anoxic media, so as to verify the validity of the available thermodynamic data concerning Re. The experimental results confirm that the predictable solubility of Re, under the conditions found in radioactive wastes storage, is very high when in the form of {ReO

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Slurry aluminizing of IN-800HT austenitic stainless steel and pure nickel. Correlations between experimental results and modelling of diffusion

Materials and Corrosion ◽

10.1002/maco.201508758 ◽

2016 ◽

Vol 67 (10) ◽

pp. 1059-1067 ◽

Cited By ~ 14

Author(s):

F. Pedraza ◽

M. Proy ◽

C. Boulesteix ◽

P. Krukovskyi ◽

M. Metel

Keyword(s):

Stainless Steel ◽

Austenitic Stainless Steel ◽

Pure Nickel ◽

Experimental Results

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Evaluation of leaching behavior and immobilization of zinc in cement-based solidified products

Hemijska industrija ◽

10.2298/hemind120228038b ◽

2012 ◽

Vol 66 (5) ◽

pp. 781-786 ◽

Cited By ~ 7

Author(s):

Damir Barbir ◽

Pero Dabic ◽

Petar Krolo

Keyword(s):

Diffusion Coefficients ◽

Experimental Results ◽

Leaching Test ◽

Test Results ◽

Zeolite A ◽

Leaching Behavior ◽

Zn Diffusion ◽

Cumulative Release ◽

Electroplating Sludge ◽

And Diffusion

This study has examined leaching behavior of monolithic stabilized/solidified products contaminated with zinc by performing modified dynamic leaching test. The effectiveness of cement-based stabilization/solidification treatment was evaluated by determining the cumulative release of Zn and diffusion coefficients, De. The experimental results indicated that the cumulative release of Zn decreases as the addition of binder increases. The values of the Zn diffusion coefficients for all samples ranged from 1.210-8 to 1.1610-12 cm2 s-1. The samples with higher amounts of binder had lower De values. The test results showed that cement-based stabilization/solidification treatment was effective in immobilization of electroplating sludge and waste zeolite. A model developed by de Groot and van der Sloot was used to clarify the controlling mechanisms. The controlling leaching mechanism was found to be diffusion for samples with small amounts of waste material, and dissolution for higher waste contents.

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Numerical Determination of Intrinsic Diffusion in Fe-Cr-Al Systems

Defect and Diffusion Forum ◽

10.4028/www.scientific.net/ddf.297-301.948 ◽

2010 ◽

Vol 297-301 ◽

pp. 948-953

Author(s):

Bartłomiej Wierzba ◽

Olivier Politano ◽

Sébastien Chevalier ◽

Marek Danielewski

Keyword(s):

Concentration Profile ◽

Diffusion Coefficients ◽

Numerical Results ◽

Multicomponent Systems ◽

Numerical Determination ◽

Intrinsic Diffusion ◽

Aluminide Coatings ◽

Interdiffusion Process

The intrinsic diffusion coefficients in diffusion aluminide coatings based on Fe-30Cr were determined at 1000oC. The diffusion fluxes were given by the Nernst Planck formulae and the Darken method for multicomponent systems was applied. This paper summarizes some numerical results to determine the composition dependent diffusivities in Fe-Cr-Al systems. The method presented in this study to obtain average intrinsic diffusion coefficients is as an alternative to the Dayananda method. Our method based on empirical parameters allowed us to predict the concentration profile during the interdiffusion process.

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Hot Corrosion of Aluminide Coated Ti-Al-Cr-Nb-Zr-Y Intermetallic Alloys

Advanced Materials Research ◽

10.4028/www.scientific.net/amr.1112.363 ◽

2015 ◽

Vol 1112 ◽

pp. 363-366 ◽

Cited By ~ 2

Author(s):

Eddy Basuki ◽

Fadhli Mohammad ◽

Ahmad Fauzi ◽

Djoko Prajitno

Keyword(s):

Corrosion Rate ◽

High Activity ◽

High Temperatures ◽

Corrosion Behavior ◽

Hot Corrosion ◽

Intermetallic Alloy ◽

Experimental Results ◽

Intermetallic Alloys ◽

Two Phase ◽

Aluminide Coatings

Pack aluminide coatings were performed on a Ti-Al-Cr-Nb alloy doped with zirconium and yttrium having two phase of a2-Ti3Al and g-TiAl microstructure. The high activity TiAl3-based coating was developed from aluminizing process carried out at 850°C for 25 hours in a pack containing 20%-wt Al, 2%wt NH4Cl, and 78%wt Al2O3. During applications at high temperatures, the coating can degrade due to the interaction between the coated system and the environment exhibit high corrosion potentials. This study investigates the hot corrosion behavior of high-activity aluminide coated Zr-Y doped a2-Ti3Al/g-TiAlCrNb intermetallic alloy at 700°C, 800°C, and 900°C in a mixture of 90% Na2SO4 and 10% NaCl. The experimental results showed that the addition of Zr and Y in the alloy reduces significantly the hot corrosion rate of the coating as resulted from the interdiffusion of these elements from the alloy to the coatings and influence the behavior of the TiAl3-based coatings.

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Characteristics of NiO present in solids obtained from hydrotalcites based on Ni/Al and Ni-Zn/Al

DYNA ◽

10.15446/dyna.v86n210.78559 ◽

2019 ◽

Vol 86 (210) ◽

pp. 58-65 ◽

Cited By ~ 1

Author(s):

Edgardo Meza Fuentes ◽

Johana Ines Rodriguez Ruiz ◽

Maria do Carmo Rangel Santos

Keyword(s):

Natural Gas ◽

Nickel Oxide ◽

Electrochemical Sensors ◽

Pure Nickel ◽

Lattice Parameters ◽

Metallic Nickel ◽

Nickel Aluminum ◽

Nickel Zinc

NiO has a variety of applications, mainly in the production of electrochemical sensors and of metallic nickel. In addition, it is widely used as catalysts to produce hydrogen from natural gas. In this work, hydrotalcites based on nickel-aluminum and nickel-zinc-aluminum were synthesized, calcined at 500 °C and studied by different techniques. It was observed that nickel-aluminum hydrotalcites are thermally more stable, collapsing at higher temperatures than hydrotalcites containing zinc. During calcination, aluminum is incorporated into NiO lattice, leading to a decrease in crystallographic parameters. However, zinc decreases this effect, favoring the formation of NiO with lattice parameters close to pure nickel oxide. Zinc also contributes to the formation of smaller NiO particles, which is very useful for its use as a catalyst. In addition, aluminum led to a distortion in NiO lattice, an effect that is minimized by zinc, showing that it hinders the incorporation of Al3+ in the NiO lattice.

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