Transmission Electron Microscopic Analysis of Micro-Twin

Abstract

Micro-twinning has been investigated in some state-of-the-art materials by transmission electron microscopy, but such characterizations have not been clear so far. Micro-twins must be characterized by identifying their spots in the electron diffraction pattern, which is very unique compared to normal defects such as dislocations or stacking faults. In this study the electron diffraction pattern which should be developed by micro-twins was derived theoretically for the [011] beam direction assuming that the symmetrical mirror plane was {112}. The angles between the diffraction spots of the (200) and (111) planes were concluded to be 15.7. This conclusion could be utilized as an indicator of the likely offset of crystal rotations or stress relaxations due to micro-twinning formation. The presence of micro-twinning should also be confirmed, by making sure that twin spots appear in the diffraction patterns and micro-twin images in dark field.