Advanced Microscopy and Characterisations and Light alloys
Dr A Gholinia
Prof J Robson
No more applications being accepted
Competition Funded PhD Project (European/UK Students Only)
Pressing of complex parts from 2xxx, 6xxx, 7xxx alloy sheets are used for automotive, aerospace, mass transport and consumer electronics markets. During the process, the material blank is heated to achieve full solutionisation before forming under defined conditions and rapid quenching in the tools. The pressed part is removed in a W temper condition, retaining the maximum solute ready for ageing to the properties required for the application.
To maximise the product quality and cost effectiveness of the process, it is necessary to fully understand the microstructural evolution. In particular, the relationship between the recrystallisation and recovery processes during deformation at high temperature and the subsequent precipitation ageing. Does the dislocation density have a critical effect on the precipitation kinetics?
There is a lot of research in the field of quantifying strain (such as mis-orientation and dislocation density measurements) and predicting material deformation (such as Schmid and Taylor factors), however the comparison of quantification and predictions do not always match. Furthermore, the link between Geometrically Necessary Dislocations (GND) and deformation paths need to be studied to achieve more accurate predictions. In the recent years the in-situ deformation in Scanning Electron Microscopy (SEM) and Electron Back Scatter Diffraction (EBSD) technology has improved, which are valuable tools to help with this project.
The University of Manchester, on using Electron Channelling Contrast Imaging (ECCI) combined with EBSD can quantify the total dislocation density in differently oriented crystals. Combining EBSD data and ECCI data would generate large datasets allowing almost complete material characterisation from one microscopy experiment. Moreover, the dislocation density data would be total rather than just the GND calculated from EBSD maps of subgrains, more statistically significant than that derived from Transmission Electron Microscopy (TEM) and more site specific than that generated from XRD line broadening experiments. Site specific characterisation can be done with preparing electron transparent samples with focused ion beam (FIB). The quantification of deformation can be done with transmission Kikutchi diffraction (TKD) in SEM and TEM. These techniques will be used for comparison. In-Situ tensile, heating experiments and EBSD in SEM will give additional information about grain orientation and mechanical properties.
Applicants should have or expect to achieve at least a 2.1 honours degree in Chemical Engineering, Materials Science, Physics, Chemistry or related disciplines.
This project is being considered for DTA funding. This would provide a full fee waiver and a EPSRC minimum stipend. International applicants are welcome to apply but will require access to self-funding.
How good is research at The University of Manchester in Electrical and Electronic Engineering, Metallurgy and Materials?
Metallurgy and Materials
FTE Category A staff submitted: 44.00
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