Atomic models of mechanical twining and <110> reorientation in bcc crystals

Atomic models of mechanical twinning and the formation of <110> reorientation bands in bcc crystals by bcc → fcc → bcc transformations with a change in the system of reverse transformations are proposed. It is shown that {112} deformation twins are formed in the process of the above transformations, when directions of shear and uniform deformation of the reverse transformation are carried out in crystallographically equivalent ones, which form 60 ° angles with the initial (direct transformation), and the orientation relationships of Kurdumov- Sachs are performed. Performing of the Nishiyama-Wasserman orientation relationships or changing in the type of orientation relationships in the process of reverse transformation leads to the reorientation of the crystal lattice of the microbands around <110> directions to angles of 60 ° or (60 ± 5.23) °. An important feature of these models is the significant contribution of the uniform deformation of the transformation of the martensitic type to the magnitude of the plastic deformation of the twin.

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