In-situ transmission electron microscopy nanoindentation investigation of the deformation behaviour of metallic amorphous/crystalline composites

Summary

This project aims to apply the in-situ TEM nanoindentation technique to understand external force induced interaction between crystalline phases and the amorphous matrix.

Supervisor(s)

Professor Xiaozhou Liao

Research Location

Aerospace, Mechanical and Mechatronic Engineering

Program Type

N/A

Synopsis

Amorphous metallic alloys have a variety of unusual properties including high elastic limit (up to 2%), super high strength (~ 2 GPa), and excellent resistance to wear and corrosion. These unusual properties have brought a wide range of applications of amorphous alloys in electronic, mechanical, and chemical industries. However, amorphous alloys suffer from their brittleness at room temperature and fail with negligible macroscopic strain (< 0.5%) under tension, which has significantly limited their applicability in reliability-critical structural applications.

The brittleness of amorphous alloys is attributed to inhomogeneous deformation or shear localisation, which results in the formation of shear bands, and strain softening. Substantial efforts have been made to explore methods that improve the ductility via, in principle, (1) promoting the generation of a large number of shear bands so that to distribute the macroscopic strain over as large volume as possible and (2) producing strain hardening that impedes shear band propagation so that to reduce the strain in a single band and delay fracture. One successful method is creating composite structures consisting of amorphous matrixes and crystalline second phases.

However, little is known on the mechanism of ductility enhancement by the composite structures and contradicted conclusions have been made by different research groups on the effect of composite structures on the ductility of the composites. This project aims to apply the in-situ TEM nanoindentation technique to understand external force induced interaction between crystalline phases and the amorphous matrix. Results obtained from this project are expected to strengthen our ability of structural design of metallic amorphous/crystalline composites with improved mechanical properties.

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Keywords

transmission electron microscopy, in-situ nanoindentation, metallic amorphous/crystalline composites, deformation behaviour

Opportunity ID

The opportunity ID for this research opportunity is: 507

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