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B. Sonderegger, E. Kozeschnik:
"On the calculation and impact of phase boundary energies on precipitate kinetics in complex alloys at high temperatures";
Talk: THERMEC´2016, Graz (invited); 2016-05-29 - 2016-06-03.

Mechanical and technological properties of alloys are significantly affected by precipitates in the microstructure. The presented work deals with aspects of modelling the kinetics of the particles. Models going beyond phenomenological calculation of phase fractions usually incorporate the energy of the phase boundary between a precipitate and the surrounding matrix. This energy contributes to the formation energy of the initial nucleus, it retards the growth of the particles and acts as driving force for coarsening processes. Therefore, it is of utmost importance to be able to model the phase boundary energies in precipitate kinetic simulations. If this quantity is not known, it has to be substituted by an according fit parameter, which is limiting the predictive capability of the according model. This work summarizes the individual approaches contributing to the General Broken Bond (GBB) concept and demonstrates its applications and limits in complex alloys. GBB takes into account thermodynamic data from precipitates and matrix, their chemical compositions, orientation and curvature of the interfaces and concentration gradients across the interface at high temperatures. Since the model is designed for multicomponent materials, it has been applied to Al-alloys, ferritic and austenitic steels and Ni-base alloys amongst others. It is discussed to what extent GBB was successfully applied, what limitations were experienced, and what kind of improvements can still be implemented.