THERMODYNAMICS OF OXYGEN SOLUTIONS IN ALUMINUM-CONTAINING Ni – Cr MELTS

Abstract

Thermodynamic analysis of the effect of aluminum on the solubility of oxygen in Ni – Cr melts has been carried out. Aluminum at  very low levels practically does not affect the concentration of oxygen  in the melt, which is determined by the chromium content. When the  aluminum content is above ~0.01  % for all alloys, it already determines the solubility of oxygen in the melt. The minimum values of  the oxygen concentration are achieved with an aluminum content of  ~0.2  %. With the increase of chromium content in the melt, the minimum oxygen concentration increases. For Ni – 10 % Cr, Ni – 20 %  Cr and Ni – 30 % Cr alloys, it is 2·10–3, 7·10–3 and 10–2, respectively.