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On‐axis versus off‐axis Transmission Kikuchi Diffraction technique: application to the characterisation of severe plastic deformation‐induced ultrafine‐grained microstructures
Author(s) -
YUAN H.,
BRODU E.,
CHEN C.,
BOUZY E.,
FUNDENBERGER JJ.,
TOTH L.S.
Publication year - 2017
Publication title -
journal of microscopy
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.569
H-Index - 111
eISSN - 1365-2818
pISSN - 0022-2720
DOI - 10.1111/jmi.12548
Subject(s) - microstructure , kikuchi line , materials science , transmission electron microscopy , diffraction , optics , perpendicular , electron backscatter diffraction , scanning electron microscope , deformation (meteorology) , electron diffraction , composite material , reflection high energy electron diffraction , geometry , nanotechnology , physics , mathematics
Summary A new configuration for Transmission Kikuchi Diffraction (TKD) in a scanning electron microscope is presented; called ‘on‐axis TKD’. Compared to the usual off‐axis configuration, the scintillator is placed perpendicular to the incident beam under the electron‐transparent sample, not in vertical position. In this way, the setup benefits from intense forward scattered electrons enabling short acquisition times. At equivalent diffraction pattern quality, the electron dose needed on the sample is estimated to be 20 times lower in comparison to the off‐axis configuration. The technique is particularly suited to the characterisation of severe plastic deformation induced ultrafine grained microstructures. The evolution of the microstructure of an Al–Mg alloy deformed by high pressure tube twisting was analysed. It is shown that the grain refinement was in the steady state stage for a shear strain of 24 with a mean grain size of 120 nm.