On simultaneous enhancement in local yield strength and plasticity of short-term annealed bulk metallic glasses

The variations in local yield strength and plasticity of a Zr-based bulk metallic glass at different fictive temperatures (T-f) are studied. To probe the size and distribution of microscopic carriers of plasticity, spherical-tip nanoindentation and microindentation are employed. With nanoindentation, events sig-nifying the departure from Hertzian elastic contact, which manifest as pop-ins in the load-displacement response and correspond to incipient plasticity, are recorded and analyzed. Results indicate that with increasing T-f, the incipient plastic event and the number of subsequent pop-ins increases. Using statistical analysis of the scatter in strength, the activation parameters for shear transformation zones (STZs) in all specimens are determined. By considering the linear accumulation of STZs to form a shear band, the increase in shear yield strength along with plasticity, with increasing T-f, is explained. (C) 2021 Elsevier B.V. All rights reserved.

Automated summary

The variations in local yield strength and plasticity of a Zr-based bulk metallic glass at different fictive temperatures were studied using nanoindentation and microindentation. The results showed an increase in incipient plastic events and subsequent pop-ins with increasing fictive temperature. Statistical analysis of strength scatter was used to determine the activation parameters for shear transformation zones (STZs) in all specimens. The increase in shear yield strength and plasticity with increasing fictive temperature was explained by considering the linear accumulation of STZs to form a shear band.