Strong and Ductile Metallic Glass Films Through Advanced Nanoarchitectural Design Strategies
Résumé
The synthesis of advanced thin film metallic glasses (TFMGs) with engineered microstructures capable to provide a large combination of mutually exclusive mechanical properties (i.e. high strength and ductility) is an open research topic. Here, I will present recent results involving two (2) strategies to finely tune the microstructure of TFMGs down to the atomic scale, resulting in outstanding and controlled mechanical behavior.
Firstly, I will show the potential of Pulsed Laser Deposition (PLD) as a novel technique to synthetize nanostructured Zr50Cu50 (%at.) TFMGs. I will show how the control of PLD process parameters enables to synthetize a variety of film microstructures among which amorphous nanogranular films showing large free volume interfaces and a nano-laminated self-assembled atomic structure [1]. This results in an unique mechanical behavior as shown by in situ TEM/SEM tensile/compression tests, reporting homogeneous deformation combined with a large yield strength (>3 GPa) and ductility (>9 %) product [1].
Then, I will focus on the fabrication of nanolaminates with nanoscale period alternating either fully amorphous or amorphous/crystalline sublayers. I will show how the control of the sublayer thickness (from 100 down to 5 nm) influences the deformation behavior affecting shear bands formation, while tuning the mechanical properties. As an example, alternating CrCoNi (crystalline)/TiZrNbHf (amorphous) nanolayers results in an ultrahigh compressive yield strength (3.6 GPa) and large homogeneous deformation (~15%) [2]. Similarly, I will show the suppression of shear band/crack process in fully amorphous (Zr24Cu76/Zr61Cu39 %at.) multilayers with bilayer period <50 nm, while keeping a mutual combination of large ductility (> 10%) and yields strength (>2.5 GPa).
Overall, our results pave the way to the development of novel amorphous materials with improved mechanical properties and wide application range.
REFERENCES:
[1] M. Ghidelli et al., Novel class of nanostructured metallic glass films with superior and tunable mechanical properties, Acta Mater., 213, 116955, 2021.
[2] G. Wu, C. Liu, A. Brognara, M. Ghidelli, ..., G. Dehm, D. Raabe, Z. Li., Symbiotic crystal-glass alloys via dynamic chemical partitioning, Materials Today, 51, 6, 2021.