  In the present paper, we have studied atomic structure of nitrogenous
austenite. High precision ab-initio calculation was utilized for the
calculation of the pair potentials of interatomic interactions N-N in FCC Fe
lattice. These potentials were used for the Monte Carlo modeling of the short
range order in the Fe-N system. It was discovered that in FCC Fe lattice,
nitrogen atoms might be partially ordered. In this case, atomic structure of
nitrogenous austenite is characterized by availability of the Fe6N phase with
the short range order over the N atoms located in the third coordination
sphere.
