The Binding Energy of Nitrogen in a Dislocation

Abstract

The solubility of interstitially dissolved nitrogen has been measured both in annealed and in cold-worked alpha iron by the internal friction technique in more detail than in the original work of Dijkstra. The dissolved nitrogen in annealed material, in equilibrium with a precipitated nitride, has a heat of solution of 0 26 eV per nitrogen atom. This agrees reasonably well with other published values. A new approach has been introduced into the treatment of the results for the solubility of nitrogen in cold-worked iron. Equilibrium is considered between nitrogen atoms in free solution and nitrogen atoms bound in dislocation sites. Since the number of dislocation sites is fixed, account is taken of the proportion of these occupied at different temperatures. The value for the binding energy of nitrogen atoms in dislocation sites is estimated as lying between 0 75 and 0.8 eV per nitrogen atom.