Dresden 2011 – scientific programme
Parts | Days | Selection | Search | Updates | Downloads | Help
MM: Fachverband Metall- und Materialphysik
MM 36: Topical Session Electron Theory V
MM 36.6: Talk
Thursday, March 17, 2011, 15:45–16:00, IFW A
Temperature dependence of the stacking fault energy in Fe0.716Cr0.200Ni0.084 alloy from first principles — •Hojjat Gholizadeh1,2, 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
The mechanism of plastic deformation of steels under mechanical stress is governed by the magnitude of the stacking fault energy (SFE). We calculate the SFE for Fe0.716Cr0.200Ni0.084 random alloy in paramagnetic austenitic phase in the temperature range 300-1500 K. Our methodology uses the axial interaction (ANNNI) model to calculate the SFE as a function of the free energies of the perfect fcc, hcp, and double-hcp crystal phases. These free energies are dependent on the lattice parameter which is obtained from experimental thermal expansion data, and on the local magnetic moments which are evaluated using DFT calculations and a Monte-Carlo simulation of a magnetic Hamiltonian of independent local moments. The DFT calculations are performed using the exact muffin-tin orbitals (EMTO) method, which enables to use the coherent potential approximation (CPA) and the disordered local moment (DLM) approaches to model the random alloy in paramagnetic state. Our results, in particular the SFE(T=300 K)=15 mJ/m2 and the hcp↔fcc transition temperature of 550 K, are in good agreement with experiments.