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Abstract

The combination of accurate first principles calculations with mesoscopic/macroscopic thermodynamic and/or kinetic concepts has quickly advanced in the past few years and allows now to tackle even complex engineering systems such as novel high-strength steels. Key to these studies is the highly accurate determination of free energies and surfaces. In the first part of the talk it will be shown how efficient sampling strategies together with high convergence density-functional theory calculations allow an accurate determination of all relevant temperature dependent free energy contributions such as electronic, harmonic, anharmonic, magnetic and structural excitations. Using these results to construct coarse grained models stability issues and mechanical properties of various alloys have been computed. The flexibility and the predictive power of this approach will be discussed in the second part of the talk for a few examples relevant to the design and understanding of high-strength steels: Determination of stacking fault energies (SFE) as critical parameter in mechanism maps, chemical trends in alloy composition or unraveling the mechanisms causing H embrittlement.