Effect of nitrogen on stacking fault energy of FCC iron-based alloys

A method is proposed to estimate the stacking fault energies of face-centered-cubic (f.c.c.) iron-based alloys. The segregation of alloying elements to stacking faults and the interaction of substitutional and interstitial alloying elements in solid solution and their effect on stacking fault energy have been taken into account. It is shown that at low nitrogen concentrations (e.g. 0.05 wt%), the stacking fault energy is increased mainly due to the effect arising from the bulk of the alloy. At high nitrogen concentration (e.g. 0.5 wt%), the stacking fault energy is decreased due to the segregation of the alloying elements (mainly nitrogen) on the stacking faults of the alloy. Moreover, it is shown that in nitrogen alloying of f.c.c. iron-based alloys the magnetic contribution of the nitrogen to the stacking fault energy is negligible. The method shows reasonable agreement with existing experimental data. (C) 1999 Acta Metallurgica Inc. Published by Elsevier Science Ltd. All rights reserved.