Solubility of nitrogen in the liquid Fe-Mo alloy

The solubility of nitrogen in liquid alloys of iron with molybdenum was pre viously determined experimentally in numerous works, and in one case by mea ns of the thermodynamic calculations of phase diagrams. The influence of mo lybdenum contained in the alloy on nitrogen solubility was interpreted by e mploying interaction parameters of the first order, e(N)((Mo)), and the sec ond order, r(N)((Mo)). In all cases, with the exception of one work, invest igations were related to temperatures little deviating from T = 1873 K. Als o, not very large (25% wt max) contents of molybdenum, with the relatively weak interaction of this element with nitrogen, might be the cause of the f ailure to reveal all possible interactions between nitrogen and molybdenum in the liquid iron alloy. Bearing the above in mind, the author's own programme of experimental inves tigations was drawn up, in which such conditions were created that all poss ible interactions in the liquid Fe-N-Mo alloy would be revealed to such an extent that they could be measured using an appropriate experimental techni que. By applying the levitation metal melting technique, nitrogen concentra tions in the alloy of iron with molybdenum were determined in the condition s of thermodynamic equilibrium within a wide range of variation of thermody namic factors, i.e. nitrogen pressure from 0.1 to 3.0 MPa, liquid metal tem perature from 1973 to 2173 K, and molybdenum concentration from 10 to 50% w t. The experimental results served for formulating the thermodynamic character istics of activity coefficient, where one of the factors, for the first tim e, is the nitrogen concentration in the alloy. By using the results of the author's earlier work on the liquid Fe-N alloy, temperature relationships o f all interaction parameters necessary for the Fe-N-Mo alloy have been defi ned. The thermodynamic data obtained in the study will constitute part of an ori ginal base for building a thermodynamic model intended for the determinatio n of nitrogen solubility in new generation steels, i.e. high-nitrogen steel s that are designated by the international abbreviation HNS.