Microchemical inhomogeneity of multicomponent systems and its evaluation from interatomic potentials

We propose to redefine the microchemical inhomogeneity parameter for a general multicomponent system and illustrate the evaluation of the parameter in a highly immiscible Ag-Ru system from an ab initio derived n-body potential via molecular dynamics simulations. It is found that the Ag-Ru system is characterized by a large positive value which is responsible for the observed phase separation behavior. Further calculations indicate a small negative value for a miscible Ni-Hf system, whereas it is around zero for a slightly immiscible Ni-Ru system, also matching well with experimental observations.