This project aims to correlate the localised electrical properties of ceramic materials and the defects present within their microstructure. A systematic approach has been developed to create crack-free deformation in oxides through nanoindentation, while the localised defects are probed in-situ SEM to study the electronic properties. A coupling of dielectric spectroscopy is made with in-situ micro/nano-mechanical testing. The correlation between defects and electrical properties provides information about the local deformation-conductivity phenomena, improving electrical properties of material, and may enable predicting failure of materials.
Despite the brittleness of oxides, we are able to deform the material without crack-formation. This is done through nanoindentation pop-in-stop experiments utilising small indenter tip dimensions [1]. Mechanical behaviour of materials in the plastic regime is studied with electron channelling contract imaging (ECCI) to identify the deformation mechanisms (Fig. 1). The novel approach of this project involves performing low-load mechanical deformation which does not lead to failure of the material (Fig. 2), as well as having the ability to locally approach the plastic zone for electrical characterisation.
Local electrical properties of deformed zones in the oxides are studied through impedance spectroscopy inside SEM. Microcontacts are deposited with GIS-FIB system, while nanometre-sharp needles are driven by the micromanipulator to probe the microcontacts. Such experiments aim to develop a correlation between the changes in the dielectric properties and the plastic deformations inside the ceramic materials. This technique represents a promising non-destructive method to improve reliability of ceramic materials at the micro- and nanoscale as well as to predict their mechanical behaviour, while they are exposed to mechanical load.
International researcher team presents a novel microstructure design strategy for lean medium-manganese steels with optimized properties in the journal Science
Smaller is stronger” is well known in micromechanics, but the properties far from the quasi-static regime and the nominal temperatures remain unexplored. This research will bridge this gap on how materials behave under the extreme conditions of strain rate and temperature, to enhance fundamental understanding of their deformation mechanisms. The…
In this project we developed a phase-field model capable of describing multi-component and multi-sublattice ordered phases, by directly incorporating the compound energy CALPHAD formalism based on chemical potentials. We investigated the complex compositional pathway for the formation of the η-phase in Al-Zn-Mg-Cu alloys during commercial…
In AM, parts are built from layer by layer fusion of raw material (eg. wire, powder etc.). Such layer by layer application of heat results in a time-temperature profile which is fundamentally different from any of the contemporary heat treatments.
Previous work in the group has established that this unique thermal profile can be exploited for microstructural modifications (eg. clustering, precipitation) during manufacturing. The aim of this work is to develop a fundamental understanding of such a strongly non-linear, peak-like thermal history on the precipitation kinetics.
Understanding the deformation mechanisms observed in high performance materials, such as superalloys, allows us to design strategies for the development of materials exhibiting enhanced performance. In this project, we focus on the combination of structural information gained from electron microscopy and compositional measurements from atom probe…
Understanding hydrogen-microstructure interactions in metallic alloys and composites is a key issue in the development of low-carbon-emission energy by e.g. fuel cells, or the prevention of detrimental phenomena such as hydrogen embrittlement. We develop and test infrastructure, through in-situ nanoindentation and related techniques, to study…