A THERMODYNAMIC MODEL FOR THE STACKING-FAULT ENERGY

A general thermodynamic model for calculating the energy of stacking f aults is presented and applied to f.c.c. Fe-Cr-Ni alloys. A distinctio n is made between ideal slacking faults and real stacking faults which are associated with an ideal stacking-fault energy (SFE) and an effec tive SFE, respectively. The ideal SFE is characterized by a chemical e nergy volume term and an interphase surface energy term, whereas the e ffective SFE is defined by an additional strain energy volume term. Th e chemical and strain energy terms are evaluated from theoretical cons iderations. The interphase surface energy is calculated based on a com parison with experimental values obtained from Transmission Electron M icroscopy (TEM) measurements. The results of this analysis show a good agreement between the calculated and experimental values. The model e nables the determination of the ideal and effective stacking fault ene rgies as a function of the Cr and Ni contents. The SFE dependence on t he Cr vs Ni contents has the shape of a hyperbola. (C) 1998 Acta Metal lurgica Inc. Published by Elsevier Science Ltd. All rights reserved.