Bulk metallic glasses

Contact: Dr. Sergio Scudino, Dr. Konrad Kosiba

The classical way to synthesize a glass consists of cooling a liquid so quickly that the crystallization is kinetically bypassed. Vitrification can be achieved even for multi-component metallic materials, the so-called bulk metallic glasses (BMGs), where cm-sized solids having liquid-like atomic arrangement can be synthesized thanks to the high viscosity of their melts. The absence of a periodic crystalline structure in these materials leads to a unique combination of properties, including near-theoretical strength, unusually large elastic limit and damage tolerance that can surpass that of conventional crystalline alloys.

Two major limiting factors preclude the extensive use of these attractive materials in functional and structural applications: (1) the small size of the specimens, which is determined by the cooling rates achievable using conventional casting methods and (2) the limited plastic deformation at room temperature, which occurs via the formation and propagation of highly-localized shear bands with thickness in the nanometer range.

Our work aims to solve these problems by focusing on three main aspects:

Synthesis and post-processing, where we optimize existing processing routes and develop new methods for the fabrication and microstructural improvement of BMGs.
Properties, where we evaluate and optimize the effect of processing on the characteristics of BMGs, in particular plasticity and shear band formation.
Analysis, where we investigate the deformation mechanism at different length scales, ranging from the µm-scale events characterizing the shear bands to the structural rearrangements occurring at the atomic scale.

In-house developed flash-annealing device

3D microhardness map of an imprinted Zr-based BMG

Schematic illustration visualizes the autocatalytic activation of shear-transformation zones and their avalanche-like combination

Strain field across a shear band obtained from nano-beam high-energy X-ray diffraction (left) and molecular dynamics simulations (right)

Selected publications:

2021 - L. Deng, L. Zhang, K. Kosiba, R. Limbach, L. Wondraczek, G. Wang, D.D. Gu, U. Kühn, S. Pauly
CuZr-based bulk metallic glass and glass matrix composites fabricated by selective laser melting
Journal of Materials Science & Technology | Volume: 81 | P. 139-150

2021 - L. Deng, K. Kosiba, R. Limbach, L. Wondraczek, U. Kühn and S. Pauly
Plastic deformation of a Zr-based bulk metallic glass fabricated by selective laser melting
Journal of Materials Science & Technology | Volume: 60 | P. 139-146

2020 - K. Kosiba, S. Scudino, J. Bednarcik, J. Bian, G. Liu, U. Kühn, S. Pauly
Guiding shear bands in bulk metallic glasses using stress fields: a perspective from the activation of flow units
Physical Review B | Volume: 102 | P. 134113/1-8

2020 - K. Kosiba, L. Deng, S. Scudino
Viscous Flow of Supercooled Liquid in a Zr-Based Bulk Metallic Glass Synthesized by Additive Manufacturing
Materials | Volume: 13 | P. 3803/1-10

2020 - L. Deng, A. Gebert, L. Zhang, H.Y. Chen, D. Gu, U. Kühn, M. Zimmermann, K. Kosiba, S. Pauly
Mechanical performance and corrosion behaviour of Zr-based bulk metallic glass produced by selective laser melting
Materials and Design | Volume: 189 | P. 108532/1-11

2019 - S. Scudino, R.N. Shahid, J.H. Han, J. Wright
Local elasticity and macroscopic plasticity in homogeneous and heterogeneous bulk metallic glasses
Applied Physics Letters | Volume: 115 | P. 141901/2-6

2019 - K. Kosiba, D. Sopu, S. Scudino, L. Zhang, J. Bednarcik, S. Pauly
Modulating heterogeneity and plasticity in bulkmetallic glasses: Role of interfaces on shear banding
International Journal of Plasticity | Volume: 119 | P. 156-170

2019 - S. Scudino
Mechanism of shear banding during cold rolling of a bulk metallic glass
Journal of Alloys and Compounds | Volume: 773 | P. 883-889

2018 - S. Scudino, D. Sopu
Strain Distribution Across an Individual Shear Band in Real and Simulated Metallic Glasses
Nano Letters | Volume: 18 | Issue: 2 | P. 1221-1227

2018 - S. Scudino, J.J. Bian, H. Shakur Shahabi, D. Sopu, J. Sort, J. Eckert, G. Liu
Ductile bulk metallic glass by controlling structural heterogeneities
Scientific Reports | Volume: 8 | P. 9174/1-7

2017 - S. Scudino, R.N. Shahid, B. Escher, M. Stoica, B.S. Li, J.J. Kruzic
Mapping the cyclic plastic zone to elucidate the mechanisms of crack tip deformation in bulk metallic glasses
Applied Physics Letters | Volume: 110 | Issue: 8 | P. 081903/1-4

2017 - D. Sopu, A. Stukowski, M. Stoica, S. Scudino
Atomic-Level Processes of Shear Band Nucleation in Metallic Glasses
Physical Review Letters | Volume: 119 | Issue: 19 | P. 195503/1-5

2017 - K. Kosiba, S. Pauly
Inductive flash-annealing of bulk metallic glasses
Scientific Reports | Volume: 7 | P. 2151/1-11