Twinning in metals is normally a permanent plastic deformation mechanism. Here we report reversible twinning in high stacking fault energy (SFE) aluminum. Twinning and spontaneous detwinning at the crack tip have been captured in situ during tensile straining under a transmission electron microscope. Both the in situ observation and the molecular dynamics simulations reveal a two-stage detwinni...

Previous density functional theory (DFT) studies of the 1/3 h1 210i screw dislocation in titanium have shown metastable core structures depending on the initial position of the dislocation line. We investigate this problem by modeling a screw dislocation with two initial positions using both DFT and a modified embedded atom (MEAM) potential for Ti with flexible boundary conditions. Both DFT and...

The elementary mechanisms controlling the interactions between lattice gliding dislocations and twin boundaries were carefully analyzed using conventional and advanced transmission electron microscopy techniques in both bulk coarsegrained Fe-Mn-C TWIP steels with deformation twins and nanocrystalline Palladium thin films with nanoscale growth twins. The results reveal that the individual disloc...

Although aluminum has a smaller modulus in [111]<112> shear than that of copper, we find by first-principles calculation that its ideal shear strength is larger because of a more extended deformation range before softening. This fundamental behavior, along with an abnormally high intrinsic stacking fault energy and a different orientation dependence on pressure hardening, are traced to the dire...