Fig. 5 Twinning planes in titanium. Although most twinning occurs along the (1 1 02) plane, deformation at room temperature also takes place along other planes. More

Fig. 27 Likelihood of twinning and cleavage for the three common lattices (fcc, bcc, and hcp). An increase in strain rate or a decrease in temperature increases the likelihood of twinning. The fcc metals twin only with difficulty and generally do not fracture by cleavage. See text More

Fig. 6 Orientation relationships for {1,1,2} ⟨1,1,−1⟩ twinning in the bcc lattice. It is assumed that a crack is propagating on the (0,0,1) cleavage plane and then on the (1,1,−2) K 1 plane in the [111] direction. (The required shear direction for simple shear twinning on the (1,1,−2) plane More

Fig. 2 Principle of twinning More

Fig. 6 Representation of mechanical twinning in a hexagonal close-packed metal. The diagonal planes are twinning planes. In the formation of a twin, each atom moves a short distance with respect to its neighbor. More

Fig. 7 Schematic comparison of crystal deformation by (a) slip and by (b) twinning More

Fig. 8 Twinning in body-centered cubic lattice resulting from shear parallel to (112) planes in the [ 1 ¯ 1 ¯ 1] direction. Source: Ref 6 More

Fig. 38 Four twinning elements: K 1 and K 2 planes, η 1 and η 2 directions, which are all contained in P, the shear plane. Source: Ref 41 . Reprinted with permission More

Fig. 5 Extensive mechanical twinning was observed in high-purity, electron-beam-melted zirconium after hot working and cold drawing. Viewed in polarized light. Magnification bar is 100 μm long. More

Fig. 4 Twinning in high-purity titanium. The twins are the needlelike bands in the grains. In some instances, the twins extend entirely across a grain. Etchant: 10% HF, 5% HNO 3 . Original magnification: 250× More

Fig. 28 Likelihood of twinning and cleavage for the three common lattices: face-centered cubic (fcc), body-centered cubic (bcc), and hexagonal close-packed (hcp). An increase in strain rate or a decrease in temperature increases the likelihood of twinning. The fcc metals twin only More

Fig. 6 Orientation relationships for {1,1,2} 〈1,1,−1〉 twinning in the body-centered cubic lattice. It is assumed that a crack is propagating on the (0,0,1) cleavage plane and then on the (1,1,−2) K 1 plane in the [111] direction. (The required shear direction for simple shear twinning More

Fig. 17 Scanning electron micrographs of defects in graphite. (a) Twinning of plates. (b) Twist boundaries. Source: Ref 73 More

Fig. 19 Schematic of twinning as it occurs in an fcc lattice. Source: Ref 11 More

Fig. 70 Centered dark-field micrograph of deformation twins imaged with 1 1 1 twin reflection. Thin foil TEM specimen More

Fig. 22 Bright-field and dark-field images of an annealing (growth) twin in rutile. (a) Bright-field image of twinned grain (arrow) in strong contrast. (b) Diffraction pattern of twinned grain showing [111] zone twinned on ( 1 01). (c) Dark-field image of matrix spot a (see Fig. 22b ). (d More

Fig. 29 Mechanical twins likely nucleated by cleavage crack propagation in a Fe-Cr-Mo alloy. Specimen taken from high strain rate, expanded tubing. Nomarski contrast illumination. Source: Ref 44 More

Fig. 8 Microcrack formation at twin intersections. (a, b, c) Incipient crack nucleation by dislocation reactions at the intersection of mechanical twins. (d) Incipient crack nucleation by strain concentration created when a growing twin intersects a previously existing twin. The direction More

Fig. 8 Fracture toughness and martensite twin density as a function of martensite start temperature for an Fe-Cr-C steel More

Fig. 17 Stacking faults (bands of closely spaced lines) and mechanical twins (the five dark, narrow bands) in 18Cr-8Ni stainless steel, deformed 5% at room temperature. Thin-foil electron micrograph. Original magnification 10,000× More