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 Effective Interdiffusion Coefficients in Experimental Investigations of Interdiffusion in Ternary Systems

2005 ◽  
Vol 237-240 ◽  
pp. 121-126 ◽  
Author(s):  
Ü. Ugaste
Keyword(s):  
Diffusion Couple ◽  
Ternary Systems ◽  
Diffusion Path ◽  
Experimental Investigations ◽  
Ternary Diffusion ◽  
Ternary Diffusion Couple ◽  
Interdiffusion Process ◽  
Variable Diffusion ◽  
Diffusion Paths ◽  
Interdiffusion Coefficients

The application of the effective interdiffusion coefficients for describing the interdiffusion process in ternary systems is discussed. It is shown that the relative values of effective interdiffusion coefficients, which are directly related to the diffusion path developed in a given diffusion couple, are responsible for deviation of the diffusion paths from linearity. The relationship between effective interdiffusion coefficients and partial (intrinsic) coefficients in ternary systems is analysed. It is shown that Boltzmann’s solution for diffusion equation with variable diffusion coefficient by means of relatively easy calculation procedure gives reliable results for the calculation concentration distributions in a ternary diffusion couple.

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

2013 ◽  
Vol 333 ◽  
pp. 73-82
Author(s):  
Ü. Ugaste ◽  
J. Priimets
Keyword(s):  
Good Accuracy ◽  
Ternary Systems ◽  
Concentration Profiles ◽  
Diffusion Couples ◽  
Ternary Diffusion ◽  
Variable Diffusion Coefficient ◽  
Ternary Diffusion Couple ◽  
Variable Diffusion ◽  
Interdiffusion Coefficients ◽  
Diffusion Profiles

A method has been developed for calculating diffusion profiles in ternary systems by using effective interdiffusion coefficients of components and Boltzmanns solution for diffusion equation with variable diffusion coefficient. Using this method the concentration profiles for several diffusion couples in the systems Fe-Co-Ni and Cu-Fe-Ni are calculated as examples and some peculiarities of these calculations are discussed, particularly, how to solve some possible difficulties, which may sometimes arise at calculation procedures. It is shown that having the data on effective interdiffusion coefficients and their concentration dependence for at least two components in a ternary diffusion couple, the concentration profiles for all three components can be calculated with good accuracy.

Investigation of Interdiffusion in High Entropy Alloys: Application of the Random Alloy Model

2019 ◽  
Vol 22 ◽  
pp. 94-108
Author(s):  
Mohammad Afikuzzaman ◽  
Irina V. Belova ◽  
Graeme E. Murch
Keyword(s):  
Diffusion Couple ◽  
High Entropy Alloys ◽  
Diffusion Couples ◽  
High Entropy ◽  
Significant Difference ◽  
Composition Profiles ◽  
Random Alloy ◽  
Explicit Finite Difference ◽  
Interdiffusion Coefficients ◽  
Good Agreement

High entropy alloys (HEAs) are composed of five or more principal elements with equal (or nearly equal) compositions. In this paper, interdiffusion phenomenon in the HEAs is investigated. Two composition dependent (as well as composition independent) interdiffusion matrices have been used for detailed studying of the diffusion behaviour in CoCrFeMnNi HEAs. These matrices are calculated according to the Darken and Manning formalisms and are used in combination with the explicit finite difference method (EFDM) to obtain interdiffusion profiles. First, the interdiffusion profiles are calculated for the case of the terminal binary diffusion couple. A significant difference in the composition profiles is found between predictions according to the Darken and Manning formalisms. Next, the interdiffusion problem in the 5-component alloy is addressed numerically by considering the interdiffusion coefficients as constant, independent of composition, in CoCrFeMnNi alloys for several diffusion couples (mainly quasi-binary and quasi-ternary). The simulated composition profiles are found to be in a very good agreement with the available experimental results [1, 2]. It should be pointed out that the independence on composition of the interdiffusion matrix should be used for diffusion couples under two conditions: relatively small changes in composition, and the non-zero/non-dilute terminal compositions. The composition dependent interdiffusion matrix should be used in the diffusion couple if the composition differences are large and/or zero/dilute terminal compositions. In this paper, the Darken and Manning formalisms are used for modelling the composition dependent interdiffusion matrices. The purpose of this modelling is to systematically investigate interdiffusion in CoCrFeMnNi alloys in diffusion couples with substantial changes in composition. The main application of the present research is in the prediction of possible interdiffusion profiles in the framework of the random alloy model.

scholarly journals Interfacial Reactions between Mg-40Al and Mg-30Y Master Alloys

Metals ◽  
2020 ◽  
Vol 10 (6) ◽  
pp. 825 ◽  
Author(s):  
Jiahong Dai ◽  
Bin Jiang ◽  
Hongmei Xie ◽  
Qingshan Yang
Keyword(s):  
Diffusion Couple ◽  
Reaction Layer ◽  
Intermetallic Phase ◽  
Diffusion Path ◽  
Interfacial Reactions ◽  
Diffusion Activation Energy ◽  
Temperature Phase ◽  
Diffusion Couples ◽  
Master Alloys ◽  
Growth Constants

Interfacial reactions between Mg-40Al and Mg-30Y master alloys were investigated at intervals of 25 °C in the 350–400 °C by using a diffusion couple method. Noticeable reaction layers were formed at the interfaces of the diffusion couples. The concentration profiles of the reaction layers were characterized. The diffusion path of the diffusion couple at 400 °C is constructed on the Mg-Al-Y ternary isothermal temperature phase diagram. The phases of the reaction layer were characterized by X-ray diffraction. The interfacial reaction thermodynamics of diffusion couples were studied. These results indicate that Al2Y is the only new formed intermetallic phase in the reaction layers. The growth constants of the reaction layers were calculated. In the reaction layer II, the integrated interdiffusion coefficients of Al are higher than Y, the diffusion activation energy of Y is higher than that of Al.

Determination of Average Ternary Interdiffusion Coefficients Using Moments of Interdiffusion Flux and Concentration Profiles

2010 ◽  
Vol 297-301 ◽  
pp. 1328-1333
Author(s):  
N. Garimella ◽  
H.J. Choi ◽  
Yong Ho Sohn
Keyword(s):  
Analysis Method ◽  
Diffusion Couples ◽  
Rigorous Solution ◽  
Ternary Diffusion ◽  
Flux Flow ◽  
Flow Equations ◽  
Interdiffusion Flux ◽  
Validation Criteria ◽  
Interdiffusion Coefficients

We developed a method of rigorous solution of the Onsager’s flow equations using moments of the interdiffusion-parameter integrands for the determination of average ternary interdiffusion coefficients. The analysis developed by Dayananda and Sohn [1] is the basis for this refined approach. Average main and cross interdiffusion coefficients are determined over selected regions in the diffusion zone using the diffusion-distance moments of the interdiffusion flux flow equations. Thermodynamic stability of solid solutions in the light of interdiffusion phenomenon is taken as validation criteria to identify accurate and reliable values of the ternary interdiffusion coefficients. Regulations are proposed for successful application of the analysis method to various ternary diffusion couples in Ni- and Fe-based intermetallics.

The Growth Rates of Intermediate Phases in Co/Si Diffusion Couples: Bulk Versus Thin-Film Studies

1989 ◽  
Vol 148 ◽  
Author(s):  
C. H. Jan ◽  
J. C. Lin ◽  
Y. A. Chang
Keyword(s):  
Experimental Data ◽  
Growth Rates ◽  
Film Studies ◽  
Bulk Diffusion ◽  
Diffusion Equations ◽  
Diffusion Couples ◽  
Intermediate Phases ◽  
Diffusion Controlled ◽  
Composition Profiles ◽  
Interdiffusion Coefficients

ABSTRACTBulk diffusion couples of Co/Si were annealed at 800, 900, 1000, 1050 and 1100°C for periods ranging from 24 hours to one month. Growth rates of the intermediate phases, Co2Si, CoSi and CoSi2, as well as the composition profiles across the couples were determined by optical microscopy and electron probe microanalysis (EPMA). Using the solution to the multiphase binary diffusion equations and the experimental data, the interdiffusion coefficients for Co2Si, CoSi and CoSi2 are obtained as a function of temperature. The activation energies obtained are 140, 160 and 190 KJ/mole for Co2Si, CoSi and CoSi2, respectively. The generally small interdiffusion coefficient of CoSi2 and its high activation energy cause the growth rate of CoSi2 to be extremely small at low temperatures.The interdiffusion coefficients for Co2Si, CoSi and CoSi2 at 545°C are obtained by extrapolation of the high-temperatures data. Using these data and solving numerically the diffusion equations with the appropriate boundary conditions, the growth of Co2Si, CoSi and CoSi2 is calculated as a function of time. The calculated results are in good agreement with the experimental data reported in the literature. This study demonstrates clearly that the initial absence of the CoSi2 phase is due to diffusion-controlled rather than nucleation-controlled kinetics. This phenomenon may be quite common in many thin-fiflm metal/Si couples.

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