Berlin 2015 – scientific programme
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MM: Fachverband Metall- und Materialphysik
MM 7: Microstructure and Phase Transformations II
MM 7.5: Talk
Monday, March 16, 2015, 12:45–13:00, H 0106
Cluster model for precipitation in Al-alloys — •Tobias Stegmüller and Ferdinand Haider — Universität Augsburg, Inst. f. Physik, 86135 Augsburg
Precipitation processes in modern aluminum alloys are due to their signifance for mechanical properties of great technical interest. Proper choice of alloying elements in precipitation hardened alloys as well as an appropriate heat treatment allows to reach middle to high strength and to control corrosion resistance.
Despite the fact, that most of these processes are well understood both qualitatively and quantitatively, there is still a lack in a precise correlation between process parameters the resulting material properties. A key role for such a correlation can be formed by a precise model allowing to simulate the kinetics of a precipitation reaction.
One approach to model unmixing in binary alloys is the so-called dynamic cluster model. The basic idea is to describe the temporal evolution of the precipitate size distribution, starting from a supersaturated homogeneous solid solution. Mathematically, this means to solve an initial value problem: taking n as number of solute atoms in one particular cluster, cn the concentration of clusters of size n, the temporal evolution is given by a master equation in terms of the respective probabilities for cluster growth and shrinkage of clusters containing n atoms.
In this work we present first results for an extended model for alloys with more than two components and with more complicated sequences of precipitate phases, as they occur in e.g. Al-Zn-Mg or Al-Cu alloys.