Interfacial kinetics of nitrogen dissolution in molten Fe-Mn-C Alloys Using ¹⁵N-¹⁴N isotope exchange reaction

The kinetics of the dissolution of nitrogen into molten Fe-Mn-C alloys through the isotope exchange reaction at 1 673 K was investigated. The rate of nitrogen dissolution into a molten Fe-Mn-C alloy at low oxygen concentrations ([mass% O] < 0.001) indicated a first-order reaction with respect to the partial pressure of nitrogen. In a molten Fe-Mn-C alloy, Mn had a positive effect on the dissolution rate of nitrogen owing to a strong thermodynamic affinity with nitrogen, while carbon produced the opposite effect. The present work on nitrogen dissolution in molten Fe-Mn-C alloys was compared to previous studies on the carbon-free Fe-Mn binary alloy, providing empirical evidence for the proportionality of the rate constant to the square of the Mn alloying element activity. It should also be noted that nitrogen dissolution into the molten Fe- Mn-C alloy could be described using a parallel reaction model for the ideal mixing between Fe and Mn, which is also discussed in detail.