Thermodynamics of the Oxygen Solutions in Titanium-Containing Fe–Co–Cr Melts

Abstract

A thermodynamic analysis of the influence of titanium on the oxygen solubility in Fe–Co–Cr melts at 1873 K is performed. The dependences of the oxygen solubility in Fe–Co–Cr melts on the titanium content are calculated. The titanium content at which the deoxidation reaction mechanism is changed (Cr₂O₃ \( \rightleftarrows \) Ti₃O₅) is as follows: 2.602 × 10^–3% Ti for the Fe–10% Co–10% Cr alloy and 2.975 × 10^–3% Ti for the Fe–20% Co–25% Cr alloy. A low titanium content insignificantly increases the oxygen concentration determined by the chromium content. At a higher titanium content (after the change of the mechanism of interaction of chromium and titanium with oxygen, when titanium determines the oxygen solubility in the melts), the oxygen concentration substantially decreases and, then, increases after passing a minimum point at a titanium content of ~0.9%. The minimum oxygen concentrations of these alloys are 1.8 × 10^–3 and 3.9 × 10^–3%, respectively.