Fig. 70 Centered dark-field micrograph of deformation twins imaged with 1 1 1 twin reflection. Thin foil TEM specimen 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. 30 Grains and deformation twins revealed by polarized light on an as-polished section of cast bismuth. 50× More

Fig. 46 Hafnium crystal bar showing twins caused by cold working. Attack polished, heat tinted at 480 °C (900 °F), and viewed under differential interference contrast illumination. 65×. (P.E. Danielson) More

Fig. 23 Equiaxed alpha grains containing annealing twins in annealed (at 750°C, or 1380 °F) wrought aluminum brass (Cu-22%Zn-2%Al) revealed by using potassium-dichromate etch, a grain-contrast etchant that responds well to polarized light More

Fig. 122 Deformation twins (some indicated by arrows) observed on the surface of (a) an otherwise intact steel T-beam removed from the fire zone and (b) the cold side of vessel V-8. Etched with 2% nital More

Fig. 30 Mechanical twins likely nucleated by cleavage crack propagation in an Fe-Cr-Mo alloy. Specimen taken from high-strain-rate, expanded tubing. Nomarski contrast illumination. Source: Ref 20 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. 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

Fig. 44 Austenitic grain structure of 316 stainless steel showing annealing twins with different etchants. (a) HCl-HNO 3 -H 2 O. (b) Tint etched with Beraha’s solution. Courtesy of George F. Vander Voort, Vander Voort Consulting More

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. 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. 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. 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. 11 Typical arrangement of a twin-roll horizontal caster used in the aluminum industry. Source: Ref 5 More

Fig. 13 Twin-belt slab caster. Courtesy of Light Metal Age. Source: Ref 6 More

Fig. 3 Cutaway drawing of a twin-channel induction melting furnace More

Fig. 7 Typical tundish design for a twin-strand slab caster. Source: Ref 4 More

Fig. 7 Schematic illustrating the twin plane re-entrant edge mechanism. (a) Crystal with a single twin. (b) Closure of twins due to ridge formation. (c) Crystal with two twins. (d) Creation of extra re-entrant corners I and II. (e) Propagation of crystal due to re-entrant corners. Source: Ref More