Abstract
The ground state of an annealed binary system with one magnetic component is discussed within the mean-field approximation. Chemical and magnetic interactions that admit two kinds of competition among the atoms are taken into account. All 11 structural and magnetic orderings allowed in a b.c.c. lattice have been determined for all concentrations p of magnetic atoms and various relations between the interaction parameters.
It is found that despite an ordering chemical potential prevailing in the system, apart from the casep = 4 when the system is homogeneous and structurally ordered, it either divides into two constituently distinct parts or separates into two coexisting phases one of which is structurally ordered and the other disordered.