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MM: Fachverband Metall- und Materialphysik

MM 15: Computational Materials Modelling IV

MM 15.2: Vortrag

Dienstag, 15. März 2011, 11:15–11:30, IFW B

A mesoscale kinetic model for alloys from atomic Monte Carlo simulations — •Thomas Garnier and Maylise Nastar — CEA, Saclay, France

Atomic Kinetic Monte Carlo (AKMC) simulations allow accurate reproduction of diffusion controlled phenomena in alloys when a rigid lattice can be assumed. However, their computational cost limits their scope. On the other hand, if the efficiency of mesoscopic methods like the Phase field method is not in question, their quantitative predictive power is not ensured most of the time. Some progress in improving the accuracy has been recently reported [1]. Following the same procedure [1], we performed Atomic Monte Carlo simulations and measured the composition fluctuation spectrum to determine mesoscopic energy parameters. To take into account the mesh resolution some finite size effects have to be considered. Another usual weakness of the phase field method is the description of the mobilities. AKMC simulations can once again be exploited to obtain the phenomenological transport coefficients associated with a vacancy diffusion mechanism. The resulting energy and kinetic parameters are then used to parameterize a Cellular Monte Carlo method, which is based on a coarse grained description of the alloy. We demonstrate that such an algorithm allows to obtain consistent results for a grid where each point represents from a few to thousands of atoms. Both thermodynamic and kinetic properties remain almost unchanged with the change of scale.

[1] Q. Bronchart & al, Phys. Rev. Lett.,100,015702,(2008)