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 Karl Franzens University Graz

Graz University of Technology 

Modeling solid-state precipitation on different length scalesModeling Precipitation in Crystalline Materials from the ab-initio to the continuum scale
Ernst Kozeschnik
Technische Universität Wien
17:15 - 18:15 Tuesday 15 June 2010 TUG P2

In this presentation, I will first give an introduction into the field of precipitation in solid-state matter. The focus of the discussion is on the early stages of the precipitation process, which is nucleation and early growth. The size of these early precipitates is commonly in the nanometer and sub-nanometer range.
After defining the phenomenological framework of precipitation kinetics, I will start discussing some of the possible approaches to model this phenomenon. On the atomistic scale, Monte Carlo and kinetic Monte Carlo offer a huge potential for obtaining introspection into the nucleus formation mechanisms, particularly in multi-component systems. The atomic interaction potentials can, at least for binary and ternary alloys, be derived from Density Functional Theory (DFT) and Cluster Expansion (CE) calculations. In higher-order multi-component systems, these data can be derived from thermodynamic databases, based on the knowledge of the enthalpies of formation of the phases as a function of chemical composition.
In the second part of the presentation, I will introduce and present a continuums model for precipitation kinetics simulation, which is being developed in our group for many years now. The underlying approaches will be briefly outlined. Finally, examples for successful applications of this model in technical alloys will be given, where treatment within purely atomistic frameworks is presently out of reach.