Calculations of energies of mixing of atoms in α- and γ-phases of Fe-Ni alloys by ab initio modeling method

Abstract

Ab initio calculations of the total energy, energy of mixing, and magnetic moments of atoms in the binary Fe-Ni alloys with the bcc and fcc lattices are carried out in the whole range of concentrations. With increasing atomic fraction of Ni x, the energy of mixing Emixγ passes the maximum, intersects the zero value, and reaches the minimum in the range of negative values. The energy of mixing of the bcc alloys in the range of nickel concentrations x = 0−0.32 is positive, which indicates that these alloys tend to clustering. The difference between the free energies of the fcc and bcc phases is calculated; the calculation result is close to the thermodynamic data of Kaufman and Cohen for 0 K.