[SY-D3] Atomistically informed atomic mobility databases for continuum diffusion simulations
Diffusion is a key aspect for microstructural evolution and has to be solved in full-field models like the phase-field model. Many phase transformations are diffusion controlled that their kinetics depend crucially on mobilities of the diffusing elements as well as their thermodynamic factor. Both parameters, the Gibbs energies and the atomic mobilities are temperature, composition and pressure dependent. Parameters representing these dependencies are stored in CALPHAD (CALculated PHAse Diagrams) type databases.
In this talk a new approach for the assessment of the temperature and composition dependence of the atomic mobility data using atomistic and experimental data is presented. The new model takes into account the physical meaning of three parameters on the basis of a mono-vacancy diffusion mechanism: the frequency factor, the vacancy formation energy and the migration energy. The temperature dependence is given by an Arrhenius equation, where the activation energy consists of the migration energy and the vacancy formation energy. The temperature dependence of both parameters is investigated using Kinetic Monte Carlo simulations. This information is used to deduce a general description of the temperature dependence of the activation energy based on these parameters. Additionally, the composition dependence of the pre-exponential factor and the activation energy is investigated separately using experimentally determined self-diffusion coefficients obtained from the tracer method and calculated self-diffusion coefficients based on kinetic Monte-Carlo simulations.
In this talk a new approach for the assessment of the temperature and composition dependence of the atomic mobility data using atomistic and experimental data is presented. The new model takes into account the physical meaning of three parameters on the basis of a mono-vacancy diffusion mechanism: the frequency factor, the vacancy formation energy and the migration energy. The temperature dependence is given by an Arrhenius equation, where the activation energy consists of the migration energy and the vacancy formation energy. The temperature dependence of both parameters is investigated using Kinetic Monte Carlo simulations. This information is used to deduce a general description of the temperature dependence of the activation energy based on these parameters. Additionally, the composition dependence of the pre-exponential factor and the activation energy is investigated separately using experimentally determined self-diffusion coefficients obtained from the tracer method and calculated self-diffusion coefficients based on kinetic Monte-Carlo simulations.