On the thermodynamic validation of two-band model potentials for FeCr

Two interatomic potentials of use for atomistic simulation of radiation damage in FeCr alloys have been recently developed using the two-band model formalism. These potentials reach the goal of providing at the same time a good description of point-defect/solute atom interaction according to ab initio data and a reasonable description of the involved thermodynamic properties of the FeCr system. In the present document these properties are overviewed and evidence is brought in support of the fact that the standard FeCr phase diagram is probably not adequate in the low-temperature and low-Cr concentration region. The capability of the potentials to actually reproduce the thermodynamic behaviour of the alloy is tested and discussed accordingly. It is found that these potentials can be safely used, from the thermodynamic point of view, below 700 K, but fail to properly reproduce the high temperature region of the solid state phase diagram. Indications for the further improvement of the potentials are proposed and discussed.