Linear-parabolic shift of initially sharp interface in AB diffusion couple above the ordering temperature

It is shown that initially sharp interface in AB diffusion couple, above the ordering temperature, can shift with anomalous kinetics, i.e. deviations from the parabolic growth kinetics are possible. The initial slopes of the shift versus time functions can be even unity for large diffusion asymmetry...

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Bibliographic Details
Published in:Philosophical magazine letters 2012-09, Vol.92 (9), p.478-486
Main Authors: Katona, G.L., Erdélyi, Z., Beke, D.L.
Format: Article
Language:English
Subjects:
anomalous diffusion
Asymmetry
Chemical interdiffusion
diffusion barriers
Condensed matter: structure, mechanical and thermal properties
Crossovers
Deviation
Diffusion
Diffusion in solids
Exact sciences and technology
interdiffusion
interface transfer coefficient
Kinetics
Materials science
Mathematical analysis
nanoscale
non-linear diffusion
Order disorder
ordering systems
Physics
shift of interface
Simulation
Temperature
Transport properties of condensed matter (nonelectronic)
Unity
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Summary:It is shown that initially sharp interface in AB diffusion couple, above the ordering temperature, can shift with anomalous kinetics, i.e. deviations from the parabolic growth kinetics are possible. The initial slopes of the shift versus time functions can be even unity for large diffusion asymmetry (the ratio of diffusion coefficients of the parent materials in orders of magnitude) and gradually decrease to 0.5 at larger distances (longer times). This is in accordance with earlier results obtained in phase separating systems. It is shown that from the results of simulations the crossover thickness, X*, between the linear and parabolic regimes can also be calculated, and the applicability of the linear-parabolic law is confirmed. Furthermore, it is illustrated that the crossover thickness depends exponentially on the diffusion asymmetry parameter, with the exponent close to the value obtained from analytical estimations.
ISSN:0950-0839
1362-3036
DOI:10.1080/09500839.2012.687837