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
In this project, we aim to design novel NiCoCr-based medium entropy alloys (MEAs) and further enhance their mechanical properties by tuning the multiscale heterogeneous composite structures. This is being achieved by alloying of varying elements in the NiCoCr matrix and appropriate thermal-mechanical processing.
The Ni- and Co-based γ/γ’ superalloys are famous for their excellent high-temperature mechanical properties that result from their fine-scaled coherent microstructure of L12-ordered precipitates (γ’ phase) in an fcc solid solution matrix (γ phase). The only binary Co-based system showing this special type of microstructure is the Co-Ti system…
In this project, we employ atomistic computer simulations to study grain boundaries. Primarily, molecular dynamics simulations are used to explore their energetics and mobility in Cu- and Al-based systems in close collaboration with experimental works in the GB-CORRELATE project.
Laser Powder Bed Fusion (LPBF) is the most commonly used Additive Manufacturing processes. One of its biggest advantages it offers is to exploit its inherent specific process characteristics, namely the decoupling the solidification rate from the parts´volume, for novel materials with superior physical and mechanical properties. One prominet…
This project studies the mechanical properties and microstructural evolution of a transformation-induced plasticity (TRIP)-assisted interstitial high-entropy alloy (iHEA) with a nominal composition of Fe49.5Mn30Co10Cr10C0.5 (at. %) at cryogenic temperature (77 K). We aim to understand the hardening behavior of the iHEA at 77 K, and hence guide the future design of advanced HEA for cryogenic applications.