Abstract
In A3B alloys of the L12 type, while the B atoms have only unlike nearest neighbours, the A atoms have a mixed neighbourhood. Therefore, the A atoms can diffuse by exchanging sites with vacancies on its own sublattice without concomitant disordering. The impurity correlation factor for such a mechanism (termed the sublattice vacancy mechanism) are calculated exactly by adopting the five-jump frequency model. The expression is compared with those for other cubic lattices derived previously.
