An Examination of Diffusion Paths in Terms of Interdiffusion Fluxes and Interdiffusion Coefficients

2007 ◽  
Vol 266 ◽  
pp. 83-99 ◽  
Author(s):  
Kevin M. Day ◽  
Mysore A. Dayananda
Keyword(s):  
National Science Foundation ◽  
Single Phase ◽  
Diffusion Path ◽  
Diffusion Couples ◽  
Eigenvalues And Eigenvectors ◽  
Internal Constraints ◽  
Two Phase ◽  
Uphill Diffusion ◽  
Diffusion Paths ◽  
Interdiffusion Coefficients

Selected diffusion couples investigated in the Cu-based and Fe-based multicomponent systems are examined for diffusion path development, zero-flux planes, uphill diffusion, and internal constraints for diffusion paths. The couples are analyzed for interdiffusion fluxes and interdiffusion coefficients with the aid of the “MultiDiFlux” program. Eigenvalues and eigenvectors are also determined from the interdiffusion coefficients determined over various ranges of composition in the diffusion zone. Slopes of diffusion paths at selected sections, including the path ends, are related to interdiffusion coefficients, interdiffusion fluxes and/or eigenvectors. These relations are explored with selected single phase diffusion couples in the Cu-Ni-Zn and Fe-Ni-Al systems and the calculated path slopes are compared with those directly determined from the concentration profiles. Relations between the gradient of interdiffusion flux and the concentration gradient are examined for each component in a two-phase Cu-Ni-Zn diffusion couple. The research is supported by the National Science Foundation.

Selected Analyses and Observations in Multicomponent Diffusion

2010 ◽  
Vol 297-301 ◽  
pp. 1451-1460 ◽  
Author(s):  
Mysore A. Dayananda
Keyword(s):  
Multicomponent Diffusion ◽  
Diffusion Couples ◽  
Uphill Diffusion ◽  
Diffusion Studies ◽  
Isothermal Diffusion ◽  
Mn Diffusion ◽  
Experimental Approaches ◽  
Diffusion Paths ◽  
Interdiffusion Coefficients

Selected isothermal diffusion studies in ternary and quaternary systems are reviewed in order to present analytical and experimental approaches adopted for the determination of interdiffusion fluxes of components, interdiffusion coefficients, diffusional interactions among components, and internal consistency in the experimental data. Several interesting phenomena and observations including uphill diffusion, zero-flux planes and flux reversals, and double serpentine diffusion paths are illustrated with selected single phase Cu-Ni-Zn, Fe-Ni-Al and Cu-Ni-Zn-Mn diffusion couples. The main challenges involved in the experimental determination of interdiffusion data from multicomponent diffusion couples and in the application of such data are also addressed.

Evolution of Concentration Profiles and Diffusion Paths in Single-Phase Multicomponent Multilayered Assemblies

2009 ◽  
Vol 289-292 ◽  
pp. 593-599 ◽  
Author(s):  
Kaustubh N. Kulkarni ◽  
Mysore A. Dayananda
Keyword(s):  
Single Phase ◽  
Middle Layer ◽  
Diffusion Path ◽  
Alloy Layer ◽  
Concentration Profiles ◽  
Uphill Diffusion ◽  
Diffusion Paths ◽  
Set Up ◽  
The Individual ◽  
And Diffusion

An analysis of multilayered assemblies set up with multicomponent alloys selected in a single phase field has been recently developed on the basis of a matrix of constant interdiffusion coefficients. This analysis employs a transfer matrix method and is applicable to a study of evolution of concentration profiles and diffusion paths as a function of time for multilayered diffusion assemblies (MDAs) where any number of finite layers is sandwiched between two bulk terminal alloys. The analysis is utilized in this study to simulate concentration profiles and diffusion paths for MDAs assembled with (fcc) Cu-Ni-Zn alloys with two terminal alloys, A and B, sandwiching an alloy layer C in the middle. For short diffusion times the diffusion path of the ternary MDA, A/C/B, corresponds to two segments corresponding to the diffusion paths of the infinite diffusion couples, A/C and C/B. At longer times the diffusion zones of the two individual couples overlap and the diffusion path of the MDA varies continuously with time. The evolution of the concentration profiles and diffusion paths is presented and each intermediate path configuration is associated with a unique ratio of the middle layer thickness to the square root of diffusion time. The simulated concentration profiles clearly show the development of uphill diffusion and zero-flux planes (ZFP) for the individual components due to diffusional interactions among the components. At very long times, the diffusion path of the MDA approaches that of the infinite couple A/B between the two terminal alloys.

Calculating of Diffusion Paths in Ternary Systems Using Effective Interdiffusion Coefficients of Components

2005 ◽  
Vol 237-240 ◽  
pp. 1264-1269 ◽  
Author(s):  
J. Priimets ◽  
A. Ainsaar ◽  
Ü. Ugaste
Keyword(s):  
Interdiffusion Coefficient ◽  
Good Accuracy ◽  
Ternary Systems ◽  
Diffusion Path ◽  
Correct Choice ◽  
Diffusion Couples ◽  
Practical Application ◽  
Strong Deviation ◽  
Diffusion Paths ◽  
Interdiffusion Coefficients

The peculiarities of practical application of effective interdiffusion coefficients of components for calculating diffusion paths in ternary systems are analysed. It is shown that infinite values of the interdiffusion coefficients at zero concentration gradient’s points do not remarkably affect the accuracy of calculation in the case of a correct choice of variables. At zero-flux planes where the respective effective interdiffusion coefficient is equal to zero, no calculation problems arise, as evidently zero-flux planes can occur simultaneously only for one of the components. The results of calculation of diffusion paths for diffusion couples in the ternary systems Cu-Fe-Ni and Co-Fe-Ni using respective effective interdiffusion coefficients are presented. These results demonstrate a good accuracy of such kind of calculations even in the case of very strong deviation from linearity of the diffusion path.

Interface Movement and Microstructure Evolution of Interdiffusion in the Binary Alloy Diffusion Couples

2011 ◽  
Vol 689 ◽  
pp. 123-129
Author(s):  
Yong Sheng Li ◽  
Yan Zhou Yu ◽  
Xiao Lin Cheng ◽  
Guang Chen
Keyword(s):  
Single Phase ◽  
Relative Concentration ◽  
Equilibrium Concentration ◽  
Diffusion Couples ◽  
Binary Diffusion ◽  
Two Phase ◽  
Concentration Difference ◽  
Initial Concentration ◽  
Interdiffusion Flux ◽  
Interface Movement

The phase field simulation of interface movement and interdiffusion microstructure in a binary diffusion couples was developed. The diffusion couples with nonequilibrium concentration for single phase or single phase and two-phase including the temperature and mobility effects were studied. It’s shown that the interface movement and the atoms diffusion direction were determined by the magnitude of relative concentration difference between the initial concentration and the equilibrium concentration, the distance of interface movement and interdiffusion flux increases as the temperature or the mobility increasing, and the large mobility makes the particles coarsening faster.

Degeneracy of diffusion paths in ternary, two‐phase diffusion couples

1996 ◽  
Vol 79 (10) ◽  
pp. 7592-7595 ◽  
Author(s):  
P. Maugis ◽  
W. D. Hopfe ◽  
J. E. Morral ◽  
J. S. Kirkaldy
Keyword(s):  
Diffusion Couples ◽  
Two Phase ◽  
Phase Diffusion ◽  
Diffusion Paths

Thermodynamic Aspects of Diffusion Paths in Ternary Systems

2007 ◽  
Vol 263 ◽  
pp. 135-140 ◽  
Author(s):  
Tony Laas ◽  
Ü. Ugaste ◽  
J. Priimets
Keyword(s):  
Thermodynamic Properties ◽  
Ternary Systems ◽  
Diffusion Path ◽  
Experimental Investigations ◽  
Ideal System ◽  
Diffusion Paths ◽  
Interdiffusion Coefficients ◽  
The Relationship ◽  
And Diffusion ◽  
Specific Influence

Description of diffusion paths is one of the most interesting and topical problems in experimental investigations of interdiffusion in multicomponent systems and, particularly, in ternary systems. The relationship between effective interdiffusion coefficients and diffusion paths in ternary systems has been discussed earlier but the specific influence of the mobility and thermodynamic properties of components on the characteristics of the diffusion path is still unclear. In this paper an attempt is made to clarify the separate influences of mobility and thermodynamics on the behavior of diffusion paths in ternary systems and the corresponding correlation is found. It is shown that in most cases the deviation of the diffusion path from linearity (an ideal system) is related to the deviation of the thermodynamic properties from the ideal. The results obtained are analyzed on the basis of thermodynamic data for the ternary system Cu-Fe-Ni.

scholarly journals Application of numerical inverse method in calculation of composition-dependent interdiffusion coefficients in finite diffusion couples

10.30544/308 ◽  
2017 ◽  
Vol 23 (3) ◽  
pp. 197-211 ◽  
Author(s):  
Yuanrong Liu ◽  
Weimin Chen ◽  
Jing Zhong ◽  
Ming Chen ◽  
Lijun Zhang
Keyword(s):  
Diffusion Couple ◽  
Inverse Method ◽  
Diffusion Path ◽  
Diffusion Couples ◽  
Ternary Diffusion ◽  
Inverse Approach ◽  
Ternary Diffusion Couple ◽  
Composition Profiles ◽  
Standard Sets ◽  
Interdiffusion Coefficients

The previously developed numerical inverse method was applied to determine the composition-dependent interdiffusion coefficients in single-phase finite diffusion couples. The numerical inverse method was first validated in a fictitious binary finite diffusion couple by pre-assuming four standard sets of interdiffusion coefficients. After that, the numerical inverse method was then adopted in a ternary Al-Cu-Ni finite diffusion couple. Based on the measured composition profiles, the ternary interdiffusion coefficients along the entire diffusion path of the target ternary diffusion couple were obtained by using the numerical inverse approach. The comprehensive comparisons between the computations and the experiments indicate that the numerical inverse method is also applicable to high-throughput determination of the composition-dependent interdiffusion coefficients in finite diffusion couples.

The Influence of Niobium on the Interdiffusion Coefficients in α2 and γ of TiAl Alloys

2013 ◽  
Vol 747-748 ◽  
pp. 85-92
Author(s):  
Dong Dong Han ◽  
Xiang Jun Xu ◽  
Lai Qi Zhang ◽  
Yong Feng Liang ◽  
Jun Pin Lin
Keyword(s):  
Electron Probe ◽  
Single Phase ◽  
Activation Enthalpy ◽  
Diffusion Couples ◽  
Arrhenius Law ◽  
Exponential Factor ◽  
Tial Alloys ◽  
Electron Probe Microanalyzer ◽  
Interdiffusion Coefficients ◽  
Significant Concentration

nterdiffusion coefficients in α2-Ti3Al and γ-TiAl of conventional TiAl and TiAl-8Nb alloy were measured at the temperature ranging from 1273K to 1523K. Single-phase diffusion couples were employed, and the concentration profiles of Al after annealing were measured by an electron probe microanalyzer (EPMA), and the interdiffusion coefficients were calculated according to the Boltzmann-Matano method. The results showed that there was no significant concentration dependence of interdiffusion coefficients for all the alloys with various phases, and the values of interdiffusion coefficients covered three orders of magnitude (E-17-E-14) with the increase of temperature according to Arrhenius law. In α2-Ti3Al and γ-TiAl phase of conventional TiAl alloys, the pre-exponential factor and activation enthalpy were D0=3.95×10-5m2s-1,Q=276KJmol-1 ;D0=7.26×10-5m2s-1,Q=275KJmol-1 respectively. The pre-exponential factor and activation enthalpy were D0=4.54×10-6m2s-1, Q=244KJmol-1 in γ-TiAl phase of TiAl-8Nb alloys. However, the temperature dependence of interdiffusion coefficients in α2-Ti3Al of TiAl-8Nb alloys did not follow Arrhenius laws very well. With the addition of Nb, the interdiffusion coefficients increased significantly in α2-Ti3Al, but changed slightly in γ-TiAl at high temperature.

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