2085.     ---------------.   [LEHRER, E.]  [Equilibrium, Iron-Hydrogen-Ammonia.]  Ztschr. Elektrochem., vol. 36, 1930, pp. 383-392; Chem. Abs., vol. 24, 1930, p. 4207.

        Many experiments in which Fe was vitrified with H₂-NH₃ mixtures were carried out, and the resulting nitrides were examined by magnetic methods (abs. 2084).  The equilibrium diagram of Fe-H₂-NH₃ showed four phases, a, γ, γ’ and ε representing five divariant equilibria and two univariant with the phases a, γ, γ’ or γ, γ’ and ε as solid phases, 350°-750°.  The a phase is a fixed solution of N in a-Fe, 0-0.5% N; the γ phase is a fixed solution of N in γ-Fe, 1-2.7% N; the γ’ phase, Fe₄N mixed crystals 5.5%-6% N; ε phase 4.5-11% N.  The dissociation pressures were calculated from the Haber values for NH₃ equilibrium.  The dependence of the results upon the concentration of NH₃ showed that the γ’ phase does not form in demonstrable amounts under normal working conditions.