Annealed Ising Ferromagnet of Binary Alloys. I

Annealed Ising ferromagnetic Binary alloys of arbitrary concentrations are solved by use of the Takagi approximation. The atom ordering energy as well as the exchange energy are taken into account. In the present paper the case that one of the component atoms is non-magnetic is studied. Since the exchange energy and the atom ordering energy disturb each other, the onset of order tends to destroy the magnetization and vice versa. Therefore several critical concentrations are found. The complete phase diagram is obtained in which a tetra-critical point exists. Complicated calculations are carried out by the analytical method as much as possible and the rest is supplemented by the natural iteration method developed by Kikuchi using the computer.