The Fe-Cr system: atomistic modelling of thermodynamics and kinetics of phase transformations

To understand the behaviour of irradiated defects and kinetic pathways of micro-structural evolution in Fe-Cr alloys, we use a combination of density functional theory (DFT) with statistical approaches involving cluster expansions and kinetic Monte Carlo (kMC) simulations. A lowest negative mixing enthalpy is found at 6.25% Cr that is consistent with our DFT prediction of an ordered Fe15Cr structure. At 50% Cr, it is found that the predicted enthalpy of formation is 4 times smaller than that calculated by the coherent potential approximation (CPA) approach. Thermodynamic and precipitation properties are then discussed in term of segregation between the Fe15Cr and α'-Cr phases and of vacancy-mediated kMC simulation. (authors)