INFLUENCE OF ATOMIC AND MAGNETIC SHORT-RANGE ORDER ON THE ORDERING OF BINARY ALLOYS WITH B. C. C. LATTICE.

The statistical theory of the ordering of binary alloys is constructed in the framework of the method of Kirkwood, allowing for atomic and magnetic correlation effects. The part played in the processes of atomic and magnetic ordering by the correlation contributions of exchange origin is demonstrated. In alloys where the ordering energy is zero, a state with negative short-range order (segregation effect) is realized at high temperatures due to the exchange interaction, and this is replaced at lower temperatures by long-range ordering. A correlation mechanism of magnetic ordering is examined which only exists in alloys and plays an important part in the formation of the magnetic structure in systems where the effective direct exchange is small.