Theoretical Analysis of the Crystallography of the Martensitic Transformation of <I>BCC</I> to 9<I>R</I> Close-Packed Structure

Abstract

A new mathematical approach of the phenomenological theory, originally developed by Suzuki, has been applied to the martensitic transformation of bcc to 9R close-packed structure which has the “ABCBCACAB” stacking order. Analytical equations for the habit plane indices and the magnitude of the lattice invariant shear are derived. The magnitude of the lattice invariant shear, the habit plane, the orientation relationship, and the shape deformation are theoretically predicted for the cases of Cu–Al and Cu–Zn alloys. Previous theoretical treatments of the crystallography of the bcc to 9R transformation are critically discussed in comparison with the present treatment.