Title
Local, atomic-level elastic strain measurements of metallic glass thin films by electron diffraction
R. Sarkar
Department of Materials Science and Engineering, School for Engineering of Matter Transport and Energy, Arizona State University
J. Rajagopalan
Department of Materials Science and Engineering, School for Engineering of Matter Transport and Energy, Arizona State University
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Abstract
A novel technique is used to measure the atomic-level elastic strain tensor of amorphous materials by tracking geometric changes of the first diffuse ring of selected area electron diffraction patterns (SAD). An automatic procedure, which includes locating the centre and fitting an ellipse to the diffuse ring with sub-pixel precision is developed for extracting the 2-dimensional strain tensor from the SAD patterns. Using this technique, atomic-level principal strains from micrometre-sized regions of freestanding amorphous Ti0.45Al0.55 thin films were measured during in-situ TEM tensile deformation. The thin films were deformed using MEMS based testing stages that allow simultaneous measurement of the macroscopic stress and strain. The calculated atomic-level principal strains show a linear dependence on the applied stress, and good correspondence with the measured macroscopic strains. The calculated Poisson's ratio of 0.23 is reasonable for brittle metallic glasses. The technique yields a strain accuracy of about 1x10-4 and shows the potential to obtain localized strain profiles/maps of amorphous thin film samples.
Keywords
Thin FilmsMetallic GlassElectron Diffraction PatternAmorphous AlloyIn-situ TEM
Object type
Language
English [eng]
Persistent identifier
Appeared in
Title
Ultramicroscopy
Volume
165
From page
51
To page
58
Publication
Elsevier BV
Version type
Date accepted
2016
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