Effect of Surface Concentration of Alloying Elements on Nitrogen Dissolution Rate in Molten Iron Alloys.

The effects of alloying elements, such as Mn, Cu and Mo, on the rate of nitrogen dissolution in the molten iron alloys are investigated by an isotope exchange technique at 1973 K. The rate constant of nitrogen dissolution increases with increasing the content of Mn or Mo, which has stronger affinity with nitrogen than iron. On the other hand, the rate constant decreases with increasing the Cu content, which has a repulsive force against nitrogen in iron. The mole fractions of the alloying elements in the surface phase are estimated, and the reaction mechanism is discussed by investigating the dependence of the rate constant on the mole fraction in the surface phase. The effect of alloying elements on the nitrogen dissolution rate depends on the affinity of the solute element with nitrogen in molten iron and the mole fraction in the surface phase.