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1.
Mysore A. Dayananda 《Journal of Phase Equilibria and Diffusion》2006,27(6):572-581
New expressions relating the interdiffusion flux of a component to its own concentration gradient in a multicomponent diffusion
couple have been derived and applied to a diffusion couple investigated in the Cu-Ni-Zn system. From these relations, effective
interdiffusion coefficients were determined at selected sections in the diffusion zone directly from the locations of the
sections relative to the Matano plane. The Cu-Ni-Zn couple was analyzed for interdiffusion fluxes and interdiffusion coefficients
with the aid of “MultiDiFlux” program developed for the analysis of interdiffusion in multicomponent systems. The couple was examined for zero-flux
plane development, interdiffusion against activity gradients, and diffusion path representation. Diffusion path slopes at
selected sections in the diffusion zone were related to the interdiffusion coefficients; slopes at path ends were determined
from eigenvectors evaluated from limiting ratios of interdiffusion fluxes. Expressions for internal consistency among the
concentration profiles or flux profiles of the individual components were also developed in terms of the terminal alloy compositions
and applied to the Cu-Ni-Zn couple in the diffusion zone.
This article was presented at the Multicomponent-Multiphase Diffusion Symposium in Honor of Mysore A. Dayananda, which was
held during TMS 2006, 135th Annual Meeting and Exhibition, March 12–16, 2006, in San Antonio, TX. The symposium was organized
by Yongho Sohn of University of Central Florida, Carelyn E. Campbell of National Institute of Standards and Technology, Richard
D. Sisson, Jr., of Worcester Polytechnic Institute, and John E. Morral of Ohio State University. 相似文献
2.
Solid-to-solid diffusion couples, β-NiAl (B2) versus various commercial superalloys (i.e., CM247, GTD-111, IN-939, IN-718, and Waspalloy) were examined to quantify the
rate of Al interdiffusion as a function of initial superalloy composition. The diffusion couples were assembled with Invar
steel jig encapsulated in Ar by sealing in quartz capsules and annealed at 1050 °C for 96 h. Concentration profiles measured
by electron probe microanalysis in the single-phase β-NiAl region were used to determine interdiffusion fluxes and effective
interdiffusion coefficients of individual components in the single-phase β-NiAl side of the couple. The values determined
using experimental concentration profiles of the single-phase β-NiAl side of the couple were used to predict effective interdiffusion
coefficients in multiphase superalloy side of the couple based on mass balance and local continuity of interdiffusion fluxes.
Microstructural and compositional stability of protective coatings (e.g., NiCoCrAlY and NiAl) as a function of superalloys
composition are discussed based on effective interdiffusion coefficients predicted from diffusion couple studies.
This article was presented at the Multicomponent-Multiphase Diffusion Symposium in Honor of Mysore A. Dayananda, which was
held during TMS 2006, 135th Annual Meeting and Exhibition, March 12–16, 2006, in San Antonio, TX. The symposium was organized
by Yongho Sohn of University of Central Florida, Carelyn E. Campbell of National Institute of Standards and Technology, Richard
D. Sisson, Jr., of Worcester Polytechnic Institute, and John E. Morral of Ohio State University. 相似文献
3.
Jérôme Colin 《Acta Materialia》2009,57(5):1454-1458
The morphological evolution of the initially planar solidification and melting fronts of a thin liquid film in a stressed binary alloy has been investigated when diffusion only proceeds in the liquid phase. A linear stability analysis has been performed and the diffusion-controlled evolution of the shape of both fronts has been characterized. The destabilizing effect of stress on the profiles of the interfaces has been identified for a liquid film at rest when the solid is submitted to constant stress and when it is migrating, due to stress gradient, in the hypothesis where concentration field of solute satisfy Laplace’s equation. The possibility of roughness formation in the early beginning of the development of the solid–liquid interfaces has been finally discussed for alloys in the context of a liquid film migration mechanism. 相似文献
4.
Ho Jin Ryu Jong Man Park Chang Kyu Kim Yeon Soo Kim Gerard L. Hofman 《Journal of Phase Equilibria and Diffusion》2006,27(6):651-658
The uranium (U)-molybdenum (Mo)/aluminum (Al) dispersion fuel that is currently under development for high-performance research
reactors has shown complicated diffusion reaction behavior between the U-Mo particles and the Al matrix. Diffusion reactions
in U-Mo/Al dispersion fuels were characterized by out-of-pile annealing tests and in-pile irradiation tests in the HANARO
research reactor. The effect of the addition of a third element such as silicon (Si), Al, or zirconium (Zr) to U-Mo fuel,
and the addition of Si to the Al matrix on the diffusion reaction were also investigated. The growth rate and activation energy
for the reaction phases of U-Mo/Al dispersion fuels were obtained. The effect of alloying a small amount of a third element
in U-Mo and of Si in the Al matrix on diffusion reaction kinetics was negligible in annealing tests conducted at ∼550 °C.
γ phase stability in the U-Mo alloy was enhanced by the addition of 0.1 to 0.2 wt.% Si. The Si accumulated in the interdiffusion
layer of U-Mo/Al-Si dispersion fuel annealed at ∼550 °C, whereas Zr migration to the interdiffusion layer of U-Mo-Zr/Al was
negligible.
This article was presented at the Multicomponent-Multiphase Diffusion Symposium in Honor of Mysore A. Dayananda, which was
held during TMS 2006, the 135th Annual Meeting and Exhibition, March 12–16, 2006, in San Antonio, TX. The symposium was organized
by Yongho Sohn of University of Central Florida, Carelyn E. Campbell of National Institute of Standards and Technology, Richard
D. Sisson, Jr., of Worcester Polytechnic Institute, and John E. Morral of Ohio State University. 相似文献
5.
A. Chauhan M. Anwar K. Montero H. White W. Si 《Journal of Phase Equilibria and Diffusion》2006,27(6):684-690
The events leading to the failure of an alloy grade HP Nb ethylene pyrolysis heater tubing were examined. X-ray maps indicated
that a complex oxide coating, which inhibits carbon (C) diffusion, forms on the process side of the tubing during service.
Phase equilibria studies predict that even without process C diffusion, metal carbides will precipitate out of the face centered
cubic (FCC_Al) matrix. It was estimated that a 6 mm thick tube operating at 1100 °C would completely carburize in two years
if the protective coating is damaged.
This article was presented at the Multicomponent-Multiphase Diffusion Symposium in Honor of Mysore A. Dayananda, which was
held during TMS 2006, 135th Annual Meeting and Exhibition, March 12–16, 2006, in San Antonio, TX. The symposium was organized
by Yongho Sohn of University of Central Florida, Carelyn E. Campbell of National Institute of Standards and Technology, Richard
D. Sisson, Jr. of Worcester Polytechnic Institute, and John E. Morral of Ohio State University. 相似文献
6.
Interdiffusion in hypothetical ternary single-phase and two-phase diffusion couples are examined using a phase-field model
by numerically solving the nonlinear Cahn-Hilliard and Ginzburg-Landau equations. For diffusion couples assembled with a regular
single-phase solution, constant chemical mobilities were used to examine the development of concentration profiles including
uphill diffusion and zero-flux plane. Zero-flux plane for a component was observed to develop for a diffusion couple at the
composition that corresponds to the activity of that component in one of the terminal alloys. Experimental thermodynamic parameters
and composition-dependent chemical mobilities were used to examine the morphological evolution of the interphase boundary
in solid-to-solid, two-phase diffusion couples. Instability at the interphase boundary was introduced initially (t=0) by a small compositional fluctuation at the diffuse interface, and its evolution varied largely as a function of terminal
alloys and related composition-dependent chemical mobility.
This article was presented at the Multicomponent-Multiphase Diffusion Symposium in Honor of Mysore A. Dayananda, which was
held during TMS 2006, the 135th Annual Meeting and Exhibition, March 12–16, 2006, in San Antonio, TX. The symposium was organized
by Yongho Sohn of University of Central Florida, Carelyn E. Campbell of National Institute of Standards and Technology, Richard
D. Sisson, Jr., of Worcester Polytechnic Institute, and John E. Morral of Ohio State University. 相似文献
7.
Narayana Garimella Yongho Sohn M. P. Brady 《Journal of Phase Equilibria and Diffusion》2006,27(6):665-670
Interdiffusion in nickel (Ni)-chromium (Cr) (face-centered cubic γ phase) alloys with small additions of aluminum (Al), silicon
(Si), germanium (Ge), or palladium (Pd) was investigated using solid-to-solid diffusion couples. Ni-Cr-X alloys having compositions of Ni-22at.% Cr, Ni-21at.%Cr-6.2at.%Al, Ni-22at.%Cr-4.0at.%Si, Ni-22at.%Cr-1.6at.%Ge, and Ni-22at.%Cr-1.6at.%Pd
were manufactured by arc casting. The diffusion couples were assembled in an Invar steel jig, encapsulated in Ar after several
hydrogen purges, and annealed at 900 °C in a three-zone tube furnace for 168 h. Experimental concentration profiles were determined
from polished cross sections of these couples by using electron probe microanalysis with pure element standards. Interdiffusion
fluxes of individual components were calculated directly from the experimental concentration profiles, and the moments of
interdiffusion fluxes were examined to determine the average ternary interdiffusion coefficients. The effects of ternary alloying
additions on the diffusional behavior of Ni-Cr-X alloys are presented in the light of the diffusional interactions and the
formation of a protective Cr2O3 scale.
This article was presented at the Multicomponent-Multiphase Diffusion Symposium in Honor of Mysore A. Dayananda, which was
held during TMS 2006, the 135th Annual Meeting and Exhibition, March 12–16, 2006, in San Antonio, TX. The symposium was organized
by Yongho Sohn of University of Central Florida, Carelyn E. Campbell of National Institute of Standards and Technology, Richard
D. Sisson, Jr., of Worcester Polytechnic Institute, and John E. Morral of Ohio State University. 相似文献
8.
《Acta Materialia》2008,56(10):2290-2295
We discuss melting of alloys along grain boundaries as a free boundary problem for two moving solid–liquid interfaces. One of them is the melting front and the other is the solidification front. The presence of the triple junction plays an important role in controlling the velocity of this process. The interfaces interact strongly via the diffusion field in the thin liquid layer between them. In the liquid film migration (LFM) mechanism the system chooses a more efficient kinetic path, which is controlled by diffusion in the liquid film over relatively short distances. However, only weak coherency strain energy is the effective driving force for LFM in the case of melting of one-phase alloys. The process with only one melting front would be controlled by the very slow diffusion in the mother solid phase over relatively large distances. 相似文献
9.
A numerical approach is presented for the segregation of atomic oxygen at Ag-MgO interfaces for a system of MgO particles
dispersed in an Ag matrix. General segregation kinetics is considered, and the coupled system of partial differential equations
is solved using a two-dimensional finite element scheme. An indirect integration procedure for the oxygen surface coverage
has been implemented into a commercial code. This numerical approach allows for the consideration of general boundary conditions,
specimen sizes, and time- or concentration-dependent material and process parameters. The method is applied to periodic and
stochastic model oxide distributions.
This article was presented at the Multicomponent-Multiphase Diffusion Symposium in Honor of Mysore A. Dayananda, which was
held during TMS 2006, 135th Annual Meeting and Exhibition, March 12–16, 2006, in San Antonio, TX. The symposium was organized
by Yongho Sohn of University of Central Florida, Carelyn E. Campbell of National Institute of Standards and Technology, Richard
D. Sisson, Jr., of Worcester Polytechnic Institute, and John E. Morral of Ohio State University. 相似文献
10.
V. Yu. Vasilev V. S. Shapkin N. V. Barulenkova M. V. Antonova E. N. Antonova 《Protection of Metals》2006,42(3):209-214
Effects of bench loading and stresses on the corrosion resistance of д16AT alloy are studied. Complicated effect of the stress
intensity and the cyclic loading on the surface morphology and pit concentration is demonstrated. Harmonic character of the
loading dependence of the change of corrosion resistance is due to segregation effects.
Original Russian Text ? V.Yu. Vasil’ev, V.S. Shapkin, N.V. Barulenkova, M.V. Antonova, and E.N. Antonova, 2006, published
in Zashchita Metallov, 2006, Vol. 42, No. 3, pp. 227–232. 相似文献
11.
Voramon S. Dheeradhada David R. Johnson Mysore A. Dayananda 《Journal of Phase Equilibria and Diffusion》2006,27(6):582-589
Diffusional analyses were performed to understand the oxidation at 1300 °C of a multiphase Mo-13.2Si-13.2B (at.%) alloy. During
oxidation, a protective glass scale formed with an intermediate layer of (Mo+glass) between the base alloy and external glass
scale. Compositional profiles across the (Mo+glass) layer and the external glass scale were determined, and interdiffusion
fluxes and effective interdiffusion coefficients for the various components were determined by using “MultiDiFlux” software. The motion of the (alloy/Mo+glass) and (Mo+glass/glass) interphase boundaries after passivation was examined.
Additionally, vapor-solid diffusion experiments at 1300 °C were carried out with single-phase Mo3Si and T2 specimens in addition to a multiphase Mo-10Si-10B (at.%) alloy. These specimens were exposed to vacuum to induce
silicon loss resulting in the formation of a Mo layer. An average effective interdiffusion coefficient of Si in Mo at 1300
°C was estimated from the Mo3Si-vapor couple to be in the order of 8×10−17 m2/s.
This article was presented at the Multicomponent-Multiphase Diffusion Symposium in Honor of Mysore A. Dayananda, which was
held during TMS 2006, 135th Annual Meeting and Exhibition, March 12–16, 2006, in San Antonio, TX. The symposium was organized
by Yongho Sohn of University of Central Florida, Carelyn E. Campbell of National Institute of Standards and Technology, Richard
D. Sisson, Jr., of Worcester Polytechnic Institute, and John E. Morral of Ohio State University. 相似文献
12.
This paper reviews new procedures based around the random alloy model that have been established recently for analyzing chemical
diffusion data in binary and ternary alloy systems. The authors show how atom-vacancy exchange frequency ratios, individual
tracer correlation factors, and vacancy-wind factors can be extracted from the chemical diffusion data. Examples are taken
from intrinsic diffusion data in the Ag-Cd and Ag-Cd-Zn alloy systems and from interdiffusion data in the Fe-Ni-Cr and Cu-Fe-Ni
alloy systems.
This article was presented at the Multicomponent-Multiphase Diffusion Symposium in Honor of Mysore A. Dayananda, which was
held during TMS 2006, 135th Annual Meeting and Exhibition, March 12–16, 2006, in San Antonio, TX. The symposium was organized
by Yongho Sohn of University of Central Florida, Carelyn E. Campbell of National Institute of Standards and Technology, Richard
D. Sisson, Jr., of Worcester Polytechnic Institute, and John E. Morral of Ohio State University. 相似文献
13.
Olga Karabelchtchikova Richard D. Sisson 《Journal of Phase Equilibria and Diffusion》2006,27(6):598-604
In the early 1970s, Professor Dayananda developed a technique for the direct integration of fluxes from the concentration
profiles in vapor-solid diffusion couples to determine diffusion coefficients and atomic mobilities. As part of a project
to control and optimize the industrial carburization process in mild- and low-alloyed steels, a modified integration analysis
was applied to determine the mass transfer coefficient in the gas boundary layer and carbon diffusivity in austenite. Because
carbon flux and surface carbon content vary with time during single-stage carburizing even with a fixed carbon potential in
the atmosphere, a mass balance at the gas-solid interface must serve as a boundary condition. This article discusses the numerical
modeling of gas carburizing, and focuses on calculating the mass transfer and carbon diffusivity parameters using the simulated
concentration profiles. This approach validates the proposed method by comparing the calculated parameters with those used
in simulation. The results were compared with previous determinations and predictions reported in the literature.
This article was presented at the Multicomponent-Multiphase Diffusion Symposium in Honor of Mysore A. Dayananda, which was
held during TMS 2006, the 135th Annual Meeting and Exhibition, March 12–16, 2006, in San Antonio, TX. The symposium was organized
by Yongho Sohn of University of Central Florida, Carelyn E. Campbell of National Institute of Standards and Technology, Richard
D. Sisson, Jr., of Worcester Polytechnic Institute, and John E. Morral of Ohio State University. 相似文献
14.
15.
Yiguang Wang Yongho Sohn Linan An Yi Fan Ligong Zhang 《Journal of Phase Equilibria and Diffusion》2006,27(6):671-675
Oxygen (O) diffusion through pure and aluminum (Al)-doped amorphous silica is investigated by using secondary ion mass spectrometry
to profile the diffusion of an18O tracer. The oxides are formed by the thermal oxidation of polymer-derived SiCN and SiAlCN ceramics. The authors demonstrate
that a small amount of Al dopant can significantly inhibit both the interstitial and network diffusion of O. The activation
energy of O network diffusion for Al-doped silica is two times higher than that for pure silica. The results are discussed
in terms of the modification of Al doping on the network structure of the otherwise pure silica.
This article was presented at the Multicomponent-Multiphase Diffusion Symposium in Honor of Mysore A. Dayananda, which was
held during TMS 2006, the 135th Annual Meeting and Exhibition, March 12–16, 2006, in San Antonio, TX. The symposium was organized
by Yongho Sohn of University of Central Florida, Carelyn E. Campbell of National Institute of Standards and Technology, Richard
D. Sisson, Jr., of Worcester Polytechnic Institute, and John E. Morral of Ohio State University. 相似文献
16.
A transfer-matrix method (TMM) is presented for the development of concentration and flux profiles in multicomponent diffusion
involving any numbern of components. From interdiffusion fluxes or concentration gradients available at an initial positionx
s, the authors derive expressions for the transfer matrix and its integral so that the concentrations or interdiffusion fluxes
of the components can be obtained at any coordinatex. The TMM requires data for interdiffusion coefficients, which are obtained as average values over selected regions by the
method of moments developed by Dayananda. Expressions for the concentrations are also obtained from initial conditions on
the fluxes or the concentration gradients. The method is also applicable to the case when all the concentrations are known
at two ends of a region over which the diffusion coefficients are considered constant. The integration of the fluxes over
time, or over the coordinatex, can be evaluated using the transfer-matrix approach, provided the value of the interdiffusion flux is given at a given coordinate.
The TMM is applicable to any number of components and can be regarded as a compact generalization of the solutions available
for ternary diffusion couples with constant interdiffusion coefficients. An application of the method is illustrated with
the experimental data for a ternary Cu-Ni-Zn diffusion couple, and the results are compared with those based on the Fujita-Gosting
solution.
This article was presented at the Multicomponent-Multiphase Diffusion Symposium in Honor of Mysore A. Dayananda, which was
held during TMS 2006, 135th Annual Meeting and Exhibition, March 12–16, 2006, in San Antonio, TX. The symposium was organized
by Yongho Sohn of University of Central Florida, Carelyn E. Campbell of National Institute of Standards and Technology, Richard
D. Sisson, Jr., of Worcester Polytechnic Institute, and John E. Morral of Ohio State University. 相似文献
17.
A large quantity of gold (approximately 10 tonnes yearly) is consumed, all over the world, just to decorate ceramic and glassware.
Due to their advanced chemical stability gold films are used for different high technology applications. The technologies
for obtaining the best “liquid bright gold” were intensively studied, but the quality of the decor coatings (films) were empirically
assessed. We proposed a scientific investigation of the characteristics of gold films, deposited on ceramic substrates, from
“liquid bright golds”. The composition of the film has been determined by EDS (Energy Dispersive X-ray Spectrometry). The
distribution of the elements was determined at the surface of the film and in cross-section. The surface distribution of the
elements was uniform. The diffusion process of the film into substrate and the migration of the substrate elements at the
interface region and into the film have been highlighted. 相似文献
18.
In binary multiphase diffusion, it is generally admitted that interfaces between phases are necessarily plane. However, a
few cases exist, as the binary diffusion couples Ni-Si, Mo-Si, and Fe-Al, for which an intermediate phase of each system grows
with an irregular needlelike morphology. To characterize the nonplanar growth of Ni3Si2 in bulk samples, the authors studied the behavior of intermetallic compound formation by optical microscopy and x-ray microtomography,
for different annealing times. They show that both the average height and the tip radius of curvature grow as the square root
of time with two diffusion coefficients separated by orders of magnitude. Moreover, x-ray diffraction indicates that the needles
are aligned along the crystallographicc-axis. These results could be consistently explained by an anisotropic diffusion model.
This article was presented at the Multicomponent-Multiphase Diffusion Symposium in Honor of Mysore A. Dayananda, which was
held during TMS 2006, 135th Annual Meeting and Exhibition, March 12–16, 2006, in San Antonio, TX. The symposium was organized
by Yongho Sohn of University of Central Florida, Carelyn E. Campbell of National Institute of Standards and Technology, Richard
D. Sisson, Jr., of Worcester Polytechnic Institute, and John E. Morral of Ohio State University. 相似文献
19.
Hiroshi Numakura Tatsuru Watanabe Makoto Uchida Yoko Yamabe-Mitarai Eisuke Bannai 《Journal of Phase Equilibria and Diffusion》2006,27(6):638-643
The diffusion in iridium-rich Ir-Nb alloys has been studied by single-phase interdiffusion experiments. The chemical diffusion
coefficient has been measured for the primary fcc solid-solution and theL12 ordered compound Ir3Nb in the temperature range between 1650 and 1950 °C, using Ir/Ir-8Nb and Ir-26Nb/Ir-28Nb diffusion couples, respectively
(numbers indicate mol%). While the chemical diffusion coefficient in the solid-solution phase is close to the tracer self-diffusion
coefficient of pure iridium, the diffusion in the compound phase is extremely slow: the chemical diffusion coefficient is
1/40 to 1/50 of that in the solid solution. The low diffusion rate in the compound must be beneficial for high-temperature
performance of refractory superalloys based on the Ir-Nb system.
This article was presented at the Multicomponent-Multiphase Diffusion Symposium in Honor of Mysore A. Dayananda, which was
held during TMS 2006, 135th Annual Meeting and Exhibition, March 12–16, 2006, in San Antonio, TX. The symposium was organized
by Yongho Sohn of University of Central Florida, Carelyn E. Campbell of National Institute of Standards and Technology, Richard
D. Sisson, Jr., of Worcester Polytechnic Institute, and John E. Morral of Ohio State University. 相似文献
20.
J. Svoboda E. Gamsjäger F. D. Fischer E. Kozeschnik 《Journal of Phase Equilibria and Diffusion》2006,27(6):622-628
The thermodynamic extremal principle is used for the treatment of the evolution of a binary system under the assumption that
all phases in the system are nearly stoichiometric with no sources and sinks for vacancies in the bulk. The interfaces between
the individual phases are assumed to act as ideal sources and sinks for vacancies, and to have an infinite mobility. Furthermore,
it is assumed that several phases are nucleated in the contact plane of the diffusion couple at the beginning of the computer
experiment. Then, it is shown that the number of newly nucleated phases determines the maximum number of polyfurcations (i.e.,
branching of a single configuration into several distinct configurations) of the initial contact (Kirkendall) plane. The model
is demonstrated on a hypothetical binary system with four stoichiometric phases. The inverse problem, namely, the determination
of the tracer diffusion coefficients in newly nucleated phases from the thicknesses of new phases and the positions of polyfurcated
Kirkendall planes, is treated too.
This article was presented at the Multicomponent-Multiphase Diffusion Symposium in Honor of Mysore A. Dayananda, which was
held during TMS 2006, the 135th Annual Meeting and Exhibition, March 12–16, 2006, in San Antonio, TX. The symposium was organized
by Yongho Sohn of University of Central Florida, Carelyn E. Campbell of National Institute of Standards and Technology, Richard
D. Sisson, Jr., of Worcester Polytechnic Institute, and John E. Morral of Ohio State University. 相似文献