Origin of Shear Stability and Compressive Ductility Enhancement of Metallic Glasses by Metal Coating.
Metallic glasses (MGs) are notorious for the poor macroscopic ductility and to overcome the weakness various intrinsic and extrinsic strategies have been proposed in past decades. Among them, the metal coating is regarded as a flexible and facile approach, yet the physical origin is poorly understood due to the complex nature of shear banding process. Here, we studied the origin of ductile enhancement in the Cu-coating both experimentally and theoretically. By examining serrated shear events and their stability of MGs, we revealed that the thin coating layer plays a key role in stopping the final catastrophic failure of MGs by slowing down shear band dynamics and thus retarding its attainment to a critical instable state. The mechanical analysis on interplay between the coating layer and shear banding process showed the enhanced shear stability mainly comes from the lateral tension of coating layer induced by the surface shear step and the bonding between the coating layer and MGs rather than the layer thickness is found to play a key role in contributing to the shear stability.
Centre For Advanced Structural Materials, Department of Mechanical Biomedical Engineering, City University of Hong Kong, Hong Kong.
B A
BA
Sun
Advanced Manufacturing Technology Research Centre, Department of Industrial and Systems Engineering, The Hong Kong Polytechnic University, Kowloon, Hong Kong.
S H
SH
Chen
Centre For Advanced Structural Materials, Department of Mechanical Biomedical Engineering, City University of Hong Kong, Hong Kong.
Y M
YM
Lu
Department of Physics and Materials Science, City University of Hong Kong, Hong Kong.
Z G
ZG
Zhu
Centre For Advanced Structural Materials, Department of Mechanical Biomedical Engineering, City University of Hong Kong, Hong Kong.
Y L
YL
Zhao
Centre For Advanced Structural Materials, Department of Mechanical Biomedical Engineering, City University of Hong Kong, Hong Kong.
Y
Y
Yang
Advanced Manufacturing Technology Research Centre, Department of Industrial and Systems Engineering, The Hong Kong Polytechnic University, Kowloon, Hong Kong.
K C
KC
Chan
Centre For Advanced Structural Materials, Department of Mechanical Biomedical Engineering, City University of Hong Kong, Hong Kong.
C T
CT
Liu