Electrical steels are a key component in electrical transformers. The traditional material is Fe, due its high magnetic permeability. Recently an improvement in efficiency has been achieved by Si doping, as this increases the resistivity (reduces eddy currents) without significantly reducing the magnetic permeability or causes large hysteresis losses. A 1% improvement in efficiency can make a huge difference to the cost of running large electricity generators and make a contribution to less wasted energy and hence help tackle climate challenges.
However, there is still considerable scope for materials improvement in electrical steels, and with the increasing demand for electric motors in many different applications, e.g. electric vehicles, there is a need for fine tuning the exact properties of the steel. This is high-end technical materials engineering.
First-principles quantum mechanical simulations have proven to be an invaluable tool for exploring and understanding the properties of materials at the nanoscale. One such simulation package is CASTEP, a density functional-based program co-developed by Probert and Hasnip at York. However, whilst materials modelling has become common-place in many different areas of materials research, it has not yet been applied to electrical steels due to the material complexity. In this PhD, we will explore the properties of various dopants in Fe, including Si, Mg and S, and progressively approach the complexity of current best-in-class electrical steels. The modelling will be multi-scale, with the characterization of defects and their impact on electrical and magnetic properties being calculated by CASTEP and then parameterized for VAMPIRE to scale up to larger samples to include the effects of grain boundaries on the magnetic properties, etc.
The second strand to this project will be the characterization of existing samples of electrical steels. In particular, there will be a detailed study of the spatial distribution of dopants, and the effect of changing the doping profile as move from the surface into the bulk of the material. The detailed measurements made will be used to refine the modelling studies.
This is a novel proposal, combining modelling and measurement, of a complex and industrially very important class of materials. Initial work on this has already been done, in consultation with Dr Fiona Robinson of Tata Steels, but there have been no publications to date. A successful proof-of-principle paper should be possible in the 1st year of the PhD, with later more detailed studies emerging in later years.