Electron Channeling Contrast Imaging (ECCI) is becoming a powerful tool in Materials Science for characterizing deformation defects. Dislocations observed by ECCI in Scanning Electron Microscope, exhibit several features depending on the crystal orientation relative to the incident beam (white/black line on a dark/bright background). In order to bring new insights concerning these contrasts, we report an original theoretical approach based on the dynamical diffraction theory. Our calculations led, for the first time, to an explicit formulation of the backscattered intensity as a function of various physical and practical parameters governing the experiment. Intensity profiles are modeled for dislocations parallel to the sample surface for different channeling conditions. All theoretical predictions are consistent with experimental results.

Abstract:In this work, plastic deformation was locally introduced at room temperature by 11 nanoindentation on a γ-TiAl based alloy. Comprehensive analyzes of microstructures were 12 performed before and after deformation. In particular, the Burgers vectors, the line directions and 13 the mechanical twinning systems were studied via accurate electron channeling contrast imaging.