Heterogeneous ordering in superlattice alloys

Abstract

The occurrence of heterogenerous ordering in ordered alloys is investigated by the differential thermal analysis (DTA) of some quenched alloys having L1₂ and B2 crystal structures. The activation energy for ordering in these alloys is deduced by Kissinger's method from these DTA data. The results are compared with the activation energy for impurity diffusion and the migration energy of vacancies, deduced by a simple calculation given by Srikrishnan and Ficalora. The activation energy for heterogeneous ordering is found to be lower than that for homogeneous ordering. It is also found that the activation energy for the former is in good agreement with the migration energy of vacancies and that for the latter agrees with the activation energy for impurity diffusion. The conditions under which heterogeneous ordering occurs, as previously proposed by the present authors, are shown to be applicable to many other alloys which are known already to exhibit heterogeneous ordering.