Activity of Nitrogen in Liquid Pure Iron

Abstract

An experimental study was made on the equilibrium of liquid pure iron and the controlled atmosphere of N₂-A mixture or N₂ only in the range of nitrogen pressure up to 2.3 atm., in the temperature range of 1566°C to 1740°C, and the following results were obtained:
(1) The solubility of nitrogen in liquid pure iron does not obey the Sieverts'law, and the nitrogen-solubility deviates positively from this law.
(2) The equilibrium constant and the free energy change in the reaction which nitrogen dissolves in liquid iron are represented by the following equations:
(3) The activity coefficient of nitrogen in liquid pure iron is represented by the following equation;
This equation is blieved to be independent of temperature over the range 1566°C to 1740°C, at least in the range 0-0.070% nitrogen.