<Original Papers>Theoretical Investigation on the Effect of Solute Atoms on the Solubility of Nitrogen in Molten Iron

On the assumption that molten iron and iron alloys maintain a quasicrystalline structure, the solubility of nitrogen in molten iron and iron alloys was theoretically investigated by using the Bragg-Williams approximation, and an equation for the interaction parameter was obtained by using a probability in which only one nitrogen atom exists at the neighbouring site of a solute atom. In order to investigate the interaction energy between solute atom, B, and nitrogen atom, N, it was assumed that (i) in molten iron all elements are characteristically ionized to some extent, (ii) the interaction energy consists of the ion-ion interaction energy, iron-election interaction energy and strain energy caused by the difference in the size factor between the solute atoms. And, the following equation was derived for the interaction energy ψ_ between B and N : ψ_=An+C where A and C are constants which have different values for each group of solute elements having the same atomic radius, and n is the effective valency obtained from a free electron model. These results were verified by the experimental data