Berlin 2008 – scientific programme

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MM: Fachverband Metall- und Materialphysik

MM 31: Mechanical Properties III

MM 31.3: Talk

Wednesday, February 27, 2008, 18:00–18:15, H 0111

Monte Carlo Simulation of Segregation Including Elastic Relaxations — •Rolf Anders and Ferdinand Haider — Universität Augsburg, Institut für Physik

We developed a real space technique which includes local atomic relaxation after each MC step, allowing thus to study processes with strong elastic contributions. The MC step consists of a vacancy jump, exchange of nearest neighbours or atom type change. The activation energy is computed using phenomenological interaction potentials (Lennard-Jones or EAM). After an accepted MC step the atomic coordinates in the vicinity of the modification are relaxed in order to minimise the total energy.

Using this method, segregation to lattice defects was simulated in NiAl and FeNi alloys. In the case of grain boundaries, the temperature dependence of the interfacial excess concentration was studied. It was found to be in good agreement with the Langmuir-McLean theory.

For an edge dislocation, the pinning force due to segregation was calculated. This was accomplished by shifting the concentration profile along the Burgers vector and subsequent relaxation of the lattice.