Displacive Phase Transformations and Generalized Stacking Faults

The displacive phase transformations can be considered as composed of two processes, namely, pure displacements, shuffling or shearing of atomic planes, and supplementary homogeneous lattice deformation changing also the dimensions of the moving planes. Such deformation causes shape memory effect when the structural transformation is reversed. General displacements of atomic planes will be examined, i.e. γ-surface type calculations will be reported for single plane shuffling, alternate shuffling of every other bcc atomic plane and successive displacements of parallel atomic planes producing in combination with homogeneous deformation the close packed structures. The results of calculations using the many-body potentials of the Finnis-Sinclair type will be compared with ab initio calculations that indicate in which way the phase transformation can be initiated.