Solubility of nitrogen in liquid Ni, Ni–Nb, Ni–Cr–Nb, Ni–Fe–Nb, and Ni–Cr–Fe–Nb systems

Abstract

By means of sampling methods, we have determined the solubility of nitrogen in liquid Ni, Ni–Nb, Ni–Cr–Nb, Ni–Fe–Nb, and Ni-18Cr-17Fe-5.2Nb systems within the temperature range from 1 773 K to 1 873 K and with the niobium content from 5 to 20 mass%. It has been found that Sieverts’ formalism successfully describes the solubility of nitrogen in all these liquid alloys up to 7 atm of the nitrogen partial pressure. Niobium addition increases the nitrogen solubility and its effect to increase nitrogen solubility is only second to chromium. Furthermore, we have derived the enthalpy and entropy of dissolution of nitrogen in these liquid alloys, determining the first order interaction parameter, eNNb(Ni, 1873 K) = ‒0.0785, up to 20 mass% Nb in nickel between nitrogen and niobium. In addition, the effects of alloying elements on the activity coefficient of nitrogen have been further investigated and the second order cross-interaction parameters between nitrogen and chromium or iron with niobium at 1 873 K have been determined as rNCrNi,Nb1873 K =0.0256 and rNFeNi,Nb1873 K =0.0115.