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Methods of Ex Situ and In Situ Investigations of Structural Transformations: The Case of Crystallization of Metallic Glasses
Published on: June 7, 2018
Probing shear-band initiation in metallic glasses
D Klaumünzer1, A Lazarev, R Maass
1Laboratory of Metal Physics and Technology, Department of Materials, ETH Zurich, Wolfgang-Pauli-Strasse 10, 8093 Zurich, Switzerland.
Physical Review Letters
|November 24, 2011
Summary
Acoustic emission monitoring captures shear band initiation in metallic glasses. This study links acoustic signals to structural dilatation, estimating a critical volume change near the glass transition temperature.
Area of Science:
- Materials Science
- Condensed Matter Physics
- Acoustics
Background:
- Metallic glasses exhibit complex deformation mechanisms.
- Shear banding is a critical failure mode in metallic glasses.
- Acoustic emission (AE) monitoring is a technique to detect micro-structural events.
Purpose of the Study:
- To investigate the initiation of shear bands in metallic glasses using in-situ acoustic emission monitoring.
- To elucidate the underlying mechanism of acoustic emission during shear band formation.
- To quantitatively estimate the critical volume change associated with shear band initiation.
Main Methods:
- In-situ acoustic emission monitoring of metallic glasses under stress.
- Analysis of acoustic signals to identify AE sources.
- Development of a model based on stick-slip flow in granular media.
- Quantitative estimation of volume change using AE data.
Main Results:
- Acoustic emission monitoring successfully captured the initiation of shear bands.
- The origin of AE was attributed to a structural dilatation mechanism.
- The critical volume change for shear band initiation was estimated to be a few percent.
- This volume change is consistent with excess free volume in the supercooled liquid regime.
Conclusions:
- Acoustic emission is a sensitive probe for shear band initiation in metallic glasses.
- Structural dilatation is a key mechanism driving AE during shear banding.
- The quantitative estimation of volume change provides insights into the nature of the glass transition.
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