ARTICLE | doi:10.20944/preprints201904.0312.v2
Subject: Chemistry And Materials Science, Materials Science And Technology Keywords: ECCI; dislocation contrast; modeled intensity profiles; invisibility criteria; dynamical theory of electron diffraction
Online: 14 May 2019 (06:14:38 CEST)
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.
ARTICLE | doi:10.20944/preprints201801.0183.v6
Subject: Chemistry And Materials Science, Materials Science And Technology Keywords: TiAl alloys; dislocation; twinning; nanoindentation; ECCI
Online: 12 February 2018 (17:07:45 CET)
In this work, plastic deformation was locally introduced at room temperature by nanoindentation on a γ-TiAl based alloy. Comprehensive analyzes of microstructures were performed before and after deformation. In particular, the Burgers vectors, the line directions and the mechanical twinning systems were studied via accurate electron channeling contrast imaging. Accommodation of the deformation are reported and a scenario is proposed. All features help to explain the poor ductility of the TiAl based alloys at room temperature.