Numerical Models of Vacancy Diffusion Based on Crystal Structure

Abstract:

The paper discusses influence of main structural factors, as the type of crystal structure and net constant, on macroscopic features of self-diffusion and interdiffusion, in an attempt to provide a consistent description of diffusion that would involve all relevant physical effects, such as Kirkendall effect, dependence of diffusion on vacancy concentration, crystallography, and concentration of individual elements.Basing on the model structure, which is a Simple Regular net along with a corresponding Wigner-Seitz cell, the principal assumptions of the proposed model are presented as well as its implications, in order to determine general relations, which can further be used in numerical calculations involving diffusion streams. Subsequently, example calculations are performed for a simplified case of a two-dimensional Simple Regular net.The conclusions reached through this line of reasoning are then extrapolated to more complicated cases of diffusion – FCC, BCC, and HCP nets – which makes possible to relate particular material structures with diffusion rates. The connection of Wigner-Seitz cells with diffusion constitutes a good demonstration of dependence of the diffusion stream on the crystallographic orientation as well on the corresponding diffusion anisotropy for complex networks.

• Periodical: Key Engineering Materials (Volume 682)
• Pages: 107-112
• DOI: https://doi.org/10.4028/www.scientific.net/KEM.682.107
• Online since: February 2016
• Authors: Michał Krośniak, Paweł Pałka, Grzegorz Boczkal
• Keywords: Diffusion Model, Kirkendall Effect, Vacancy Diffusion, Wigner-Seitz Cell

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