Berlin 2018 – scientific programme

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MM: Fachverband Metall- und Materialphysik

MM 44: Topical Session (Symposium EPS and MM): Mechanical Properties at Small Scales

MM 44.4: Talk

Wednesday, March 14, 2018, 18:00–18:15, H 0107

Viscoelastic stress relaxation of amorphous TiAl thin film under tension measured by selected area electron diffraction — •Christian Ebner¹, Rohit Sarkar², Jagannathan Rajagopalan², and Christian Rentenberger¹ — ¹University of Vienna, Physics of Nanostructured Materials, Boltzmanngasse 5, 1090 Vienna, Austria — ²Arizona State University, Department of Materials Science and Engineering, School for Engineering of Matter Transport and Energy, Tempe 85287, USA

Amorphous samples loaded by an external stress show a time-dependent viscoelastic strain response. To study this behaviour on small scaled samples, in-situ tensile tests are performed on amorphous TiAl in a Philips CM200 transmission electron microscope. Selected area electron diffraction (SAED) is used as a method to extract the local atomic-level elastic strain, since elliptic distortions of the radial intensity maxima positions are introduced in the SAED patterns by tensile straining [1]. By precisely measuring these distortions, the 2-dimensional strain tensor is calculated with respect to a reference pattern. This allows to quantify the principal strain e₁ (parallel) and e₂ (perpendicular to the loading direction) as a function of the external stress σ. The viscoelastic response to stress jumps is measured by the time dependent changes in principal strain Δ e₁.

[1] Ebner et al. (2016) Ultramicroscopy, 165, 51-58.

C. E. and C. R. acknowledge financial support by the Austrian Science Fund FWF: [I1309]. R. S. and J. R. acknowledge funding from the NSF grants CMMI 1400505 and DMR 1454109.