Scanning and transmission electron microscopy investigations of defect arrangements in a two-phase γ-TiAl alloy

Different methods of scanning and transmission electron microscopy (SEM, TEM) were applied on a γ-TiAl alloy TNB-V5 after a thermo-mechanical fatigue test. Electron channelling contrast imaging (ECCI) and electron backscattered diffraction were carried out on bulk specimen. In addition, ECCI and scanning transmission electron microscopy in the SEM were carried out on a TEM foil in the electron opaque and the electron transparent region, respectively. The investigations were completed by transmission electron microscopy in the form of standard bright field imaging as well as by taking corresponding diffraction patterns. The results demonstrate in an impressive way that the ECCI technique applied in scanning electron microscopy can successfully supplement or in some cases replace imaging of dislocation arrangements in TEM.