Activity of Sulfur in Solid Fe-Cr Alloys and Their Equilibrium Relations with Sulfides at 1 573K

Abstract

Equilibrium between solid iron-chromium alloys and H₂-H₂S gas mixture was measured using a gas circulating method, to determine the activity of sulfur in the alloys at 1 573K.
An isothermal section of the Fe-Cr-S system at 1 573 K was experimentally determined over the metal/sulfide equilibrium region using a conventional silica capsule technique. The thermodynamic evaluation procedure based on a modified GIBBS-DUHEM integration was applied to the experimentally obtained tie-line distribution and phase relations, and a stability diagram was obtained. This revealed the existence of stable fields of the metal and sulfide phases as a function of the partial pressure of sulfur and the metal ratio. The solubility of sulfur in the Fe-Cr alloy was also determined.