Fig. 3: Schematic illustration of the dual-step twinning nucleation mechanism.
From: Direct observation of dual-step twinning nucleation in hexagonal close-packed crystals
a Unit-cell of a HCP structure. Solid balls represent individual atoms. b <1 1 −2 0 > -projection view of the unit-cell. The prismatic plane (P), basal plane (B), twinning plane (K1), and conjugate twinning plane (K2) are colored magenta, blue, yellow, and turquoise, respectively, for easy tracking of their corresponding planes after the transformations. Arrows in c, d indicate the atomic movements required to accomplish the transformations of the unit-cell; in particular, blue arrows in d indicate the portion that delivers the homogeneous shear. e Twin embryo structure generated by the P → B transformation, which shows a minor rotational deviation compared with the ideal twin f. Angle of the minor rotation can be described by tan−1(s/2), where s is the magnitude of twinning shear (see Supplementary Fig. 2 for the derivation).
