Electron beam induced rejuvenation in a metallic glass film during in-situ TEM tensile straining

Author(s)
Christian Ebner, Jagannathan Rajagopalan, Christina Lekka, Christian Rentenberger
Abstract

Rejuvenation of an amorphous TiAl thin film under external tensile stress by high energy electron irradiation is observed via in-situ transmission electron microscopy (TEM). Electron beam (e-beam) irradiation results in a characteristic change of the elastic properties over time, as measured by the atomic-level elastic strain contained in the TEM diffraction pattern. Specifically, a time dependent increase/decrease of elastic strain is observed along the tensile direction, the saturation value of which correlates linearly with the preceding stress increment/decrement but shows little dependence on the e-beam condition. The low sensitivity of the saturation value to the e-beam condition indicates that the elastic strain change is induced by the structural transitions of a population (dependent on stress increment/decrement) of unstable atomic configurations to local, elastically soft areas. Classical molecular dynamics (MD) simulations including high energy electron scattering events are performed under tensile load to obtain insights into the structural modification that leads to time dependent changes in elastic strain under irradiation. The simulations reveal a change in quantities that are characteristic of structural rejuvenation, with a reduction of the local shear modulus manifesting as time dependent increase in the atomic-level elastic strain at fixed external stress. This link to the experimental data is confirmed by tracking elliptic distortions of simulated diffraction patterns calculated from MD configurations. The presented findings are highly relevant for experimental characterization of amorphous materials using TEM and give a new perspective on local structural modifications by electron irradiation.

Organisation(s)
Physics of Nanostructured Materials
External organisation(s)
Arizona State University, University of Ioannina
Journal
Acta Materialia
Volume
181
Pages
148-159
No. of pages
12
ISSN
1359-6454
DOI
https://doi.org/10.1016/j.actamat.2019.09.033
Publication date
12-2019
Peer reviewed
Yes
Austrian Fields of Science 2012
Materials physics, Electron microscopy
Keywords
ASJC Scopus subject areas
, , ,
Portal url
https://ucris.univie.ac.at/portal/en/publications/electron-beam-induced-rejuvenation-in-a-metallic-glass-film-during-insitu-tem-tensile-straining(d06f5911-d1a0-4078-b9a6-878fbe99c9ea).html