Ab initio analysis of energetics of σ-phase formation in Cr-based systems -: art. no. 174104

A theoretical approach to the explanation of experimentally determined positive enthalpy of formation in Cr-based sigma phases is presented. It turns out that the energy of formation of sigma phases in Cr-Co and Cr-Fe systems is found to be negative taking the pure components in the sigma -phase structure as the standard states. Our treatment represents a first step to a model of an explanation of the stability of the sigma phase.