Abstract Scope |
In this talk, I will present our recent studies that integrate in situ electron microscopy mechanical testing and atomistic modeling to investigate the deformation twinning mechanisms in FCC, BCC and HCP crystals. For example, we have unraveled a previously unknown mechanism of dual phase transformations from FCC to HCP and back to FCC with nanotwins in a nanostructured medium-entropy alloy of CrCoNi. We have observed the occurrence of anti-twinning in BCC W previously thought impossible. In addition, our atomistic simulations have revealed a dislocation-mediated mechanism of twin nucleation and growth in BCC crystals, as supported by in situ transmission electron microscopy observations. Finally, I will present a study of surprisingly large twinning shear of 120% in HCP crystals. The ability to resolve the atomic-scale twinning processes, through coupled modeling and in situ experiment, enables a deep understanding of how deformation twinning affects the plastic behavior of crystalline materials. |