Seminar: Andrea Brognara

December 02, 2022

13:00

BARB13

Title:

Effect of composition and nanolayering on mechanical properties of Zr100-xCux thin film metallic glasses

Abstract:

Thin film metallic glasses (TFMGs) are a novel class of promising materials showing a mutual combination of large plastic deformation in tension (above 10%) and superior yield strength (~3.5 GPa) [1]. In our work we studied the effect of composition on the mechanical properties of Zr100-xCux TFMGs. Exploiting several techniques including nanoindentation, surface Brillouin spectroscopy, tensile tests on flexible substrates, X-Ray diffraction and transmission electron microscopy (TEM), we show how film composition can control hardness and elastic modulus, but also cracking resistance, which increases for Cu-rich films, able withstand elongation up to 2% before cracking initiates [2]. Finally, we focused on the synthesis of fully amorphous multilayers with different nanoscale periodicity to exploit interfaces to obstacle crack propagation and further improve the mechanical properties. For instance, we report large hardness (~12 GPa) when the bilayer thickness is down to 50 nm (Fig. a) and improved resistance to crack propagation. What is more, in-situ micropillar compression (Fig. b) and TEM investigation show how the presence of interfaces can interfere with the deformation processes and propagation of shear bands. Overall, our results pave the way to the development of novel amorphous materials with improved mechanical properties and wide application range.

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