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Nanoscale engineering of interfaces in alloys
Keywords: disconnections, mobility, triple line
The strength and reliability of engineering materials is related to the internal microstructure, which includes materials imperfections (e.g., interfaces, impurities, dislocations) with their respective size and distances to each other. Nanostructured materials have extraordinary and unexpected properties compared to traditional engineering alloys due to a nanoscale microstructure.
These nanostructures of engineering materials have an internal length scale imposed by the spacing of imperfections (i.e., interfaces), which can be phase boundaries in nanocrystalline metals or nanocomposites and/or free-surfaces in, for example, nanowires or nanoparticles. In general, the emerging strength, reliability and stability is related to the properties of these interfaces and how these interfaces interaction with other imperfections in nanomaterials.
This project aims to relate the interface structure to the interface properties of advanced engineering materials by using atomistic simulations methods on high-performance computers and by testing machine learning strategies in their predictive power.
Impurity effects in refractory alloys
Keywords: solute drag, mobility, thermally activated plasticity
For a significant increase in operating temperatures in energy conversion processes, alternative constituent phases for new high-temperature alloys beyond tradition Ni-basis superalloys have to be explored. Candidate materials that come to mind because of their high melting points are refractory metals such as V, Cr, Nb, Mo, Ta or W.
But refractory elements typically show low fracture toughness and ductility at low temperature and endanger the structural integrity of, for example, turbines. In fact, body centred cubic metals typically show a ductile-brittle transition at a certain temperature, which can be extremely sensitive to small variation of impurity levels.
Using atomistic simulations on high performance computer, the role of impurities on the defect nucleation and migration is investigated to extract and compare their experimental signatures on the deformation behaviour associated with impurity-induced brittleness. The goal is to develop a simulations-informed predictive map of impurity sensitivity on the brittle-ductile transition.
Scholarships are available.