Regensburg 2010 – wissenschaftliches Programm
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MM: Fachverband Metall- und Materialphysik
MM 4: Topical Session Designing Innovative Structural Materials and Steels II
MM 4.5: Vortrag
Montag, 22. März 2010, 12:30–12:45, H4
DFT-based calculation of temperature-dependent stacking fault energy in the Fe-Mn alloy — •Andrei Reyes-Huamantinco1,2, Andrei Ruban3, Peter Puschnig1, and Claudia Ambrosch-Draxl1 — 1Chair of Atomistic Modelling and Design of Materials, University of Leoben, Austria — 2Materials Center Leoben, Austria — 3Applied Material Physics, Royal Institute of Technology, Stockholm, Sweden
We have studied the Fe-22.5at.%Mn alloy in the temperature range between 300 and 800 K. The random alloy in the paramagnetic state was modelled by the coherent potential approximation (CPA) and the disordered local moment (DLM) approach. The DFT-calculations were carried out using the exact muffin-tin orbitals (EMTO) method. Temperature-dependent lattice parameter and local magnetic moment were used in constrained DFT-calculations. The former was obtained from measurements, while the latter was calculated through a longitudinal spin-fluctuation (LSF) Hamiltonian in combination with Monte Carlo simulations. The stacking fault energy (SFE) was expanded in terms of free energies of the fcc, hcp and dhcp structures, including electronic and magnetic entropies. We find that the SFE increases by 17 mJ/m2 between 300 and 600 K, and that the hcp/fcc transformation temperature is 390 K, in agreement with experiments.