Structure relationships between the binary fcc and bcc superstructures

Abstract The development of superstructures derived from simple crystal structures under equilibrium conditions provides valuable information about the energetics of the atomic interactions. Moreover, collective deformation processes of superstructures as in martensitic transformations or during twinning can retain atomic correspondences leading also to non-equilibrium superstructures. Against this background, the exhaustively enumerated superstructures of the body-centered cubic structure (bcc) and of the cubic close packed structure (fcc) up to 4 atoms per primitive unit cell were analysed in view of their behavior upon the Bain deformation and Σ3 (pseudo)twinning processes. It turns out that the enumerated superstructures form various closed sets which are intertransformable in these ways. This fact can be attributed to the mathematical characteristics of the enumeration process. The consequences of these types of intertransformation processes between prominent and less prominent bcc and fcc superstructures having in reality different energies are discussed in view of the effect of ordering on martensitic transformations.