A thermodynamic model for the stacking-fault energy

A general thermodynamic model for calculating the energy of stacking faults is presented and applied to f.c.c. Fe-Cr-Ni alloys. A distinction is made between ideal slacking faults and real stacking faults which are associated with an ideal stacking-fault energy (SFE) and an effective SFE, respectively. The ideal SFE is characterized by a chemical energy volume term and an interphase surface energy term, whereas the effective SFE is defined by an additional strain energy volume term. The chemical and strain energy terms are evaluated from theoretical considerations. The interphase surface energy is calculated based on a comparison with experimental values obtained from Transmission Electron Microscopy (TEM) measurements. The results of this analysis show a good agreement between the calculated and experimental values. The model enables the determination of the ideal and effective stacking fault energies as a function of the Cr and Ni contents. The SFE dependence on the Cr vs Ni contents has the shape of a hyperbola. (C) 1998 Acta Metallurgica Inc. Published by Elsevier Science Ltd. All rights reserved.