This thesis concerns computer
simulation of diffusional processes in alloys. The main focus is
on the development of simulation techniques for diffusion in
single-phase domains, but also diffusion controlled
phase-transformations and interfacial processes are discussed.
simulation techniques for studying the Kirkendall effect are
developed and analyzed. Comparisons with experimentally observed
marker migration show good agreement for small shifts and
comparisons with observed Kirkendall porosity show reasonable
agreement under the assumption that a certain supersaturation is
needed before the vacancies coalesce into pores.
A convenient approach in
simulations of kinetics is to use thermodynamic software, e.g.
Thermo-Calc, to calculate thermodynamic quantities, e.g.
chemical potentials, required in the simulation. The main
drawback with such an approach is that it will generate a large
amount of additional computational work. To overcome this
problem a method that decreases the amount of computational work
has been developed. The new method is based on artificial neural
networks (ANN). By training the ANN to estimate thermodynamic
quantities a significant increase in computational speed was
By calculating the
dissipation of available driving force due to diffusion inside
migrating interfaces an approach for including the effect of
solute drag in computer simulations of grain growth and phase
transformations has been developed. The new method is based on
an effective interfacial mobility and simulations of grain
growth have been performed in binary and ternary systems using
experimentally assessed model parameters.
Kirkendall effect, Phase transformations, Random walk, Solute
drag, Interfacial mobility