Deformation twinning at the tip of a straight crack or notch is analyzed using a phase-field method that seeks equilibrium twin morphologies via direct minimization of a free energy functional. For isotropic solids, the tendency to twin under mode I or mode II loading is found to depend weakly on Poisson’s ratio and elastic nonlinearity and strongly on surface energy and twinning shear (i.e. ei...

in order to investigate deformation history preserved in the calcite twins in the hinterland of zagros, several samples have been collected from calcschists of the paleozoic sargaz complex in the faryab area, se iran. these samples are related to f1-recumbent folding and thrust shear zones. the twin width is about 1 and 3.8 µm (thin-twin regime); the twin strain amounts 5 and 10%; twin intensit...

microstructural evolutions of twinning induced plasticity (twip) steel during tensile straining wereinvestigated by in situ sem observations. the results indicated that slip lines and mechanical twins aswell as surface relief were increased with increasing strain, resulting in a stepped surface. additionally,these deformation mechanisms could change the shape of each grain via shear and rotatio...

Nanotwins in nanocrystalline Mg–Alalloys: an insight from high-resolutionTEM and molecular dynamics simulation Report Title Twinning in hexagonal close-packed Mg alloys has been reported to be unfavorable when the grain size is reduced below a couple of microns and suppressed at the nanoscale. Using high-resolution transmission electron microscopy, we present evidence of nanotwins (<1 nm) in na...

A microstructural investigation of stishovite-bearing quartzite from the Vredefort meteorite impact site in South Africa reveals features that are attributed to shock deformation. These include abundant mechanically induced Dauphiné twinning, rhombohedral deformation lamellae and associated residual stresses. Mechanical twins were identified with SEM-EBSD. Residual stresses are derived from equ...

We identify the role of deformation twinning and twin–twin intersections on the strain hardening behavior of Hadfield steel single crystals using strain field measurements. In situ and ex situ strain field measurements resolved at micrometer length scales are obtained using digital image correlation. Ex situ measurements reveal that macroscopic twin-bands, which are composed of a mixture of fin...

The {111}<11 2 > shear stress-displacement behavior for face-centered cubic (fcc) metals, aluminum and copper, is calculated using empirical potentials proposed by Mishin and by Ercolessi, based on the embedded atom method (EAM), and compared with published ab initio calculations. In copper close agreement is observed in the results given by the Mishin potential for both the ideal shear strengt...