PhD Research Project: Nanostructured Tungsten Alloys for Nuclear Fusion

A 3-year UK/EU PhD studentship is available in the group of Dr Sandy Knowles within the School of Metallurgy and Materials at the University of Birmingham, with a stipend of £14,777 per year.
This project is supported by Culham Centre for Fusion Energy (CCFE), who will provide both industrial supervision and access to irradiation testing facilities.

The research group investigates new alloys for extreme environments in nuclear fusion/fission reactors as well as aerospace gas turbines. This involves the design of new alloys; production through arc melting, powder metallurgy or additive manufacturing; characterisation using electron microscopy and x-ray diffraction; mechanical testing using macro/micro-mechanical methods and failure investigation.

Nuclear fusion offers the prospect of large-scale low carbon energy with no long-lived radioactive waste. Over 50 years of worldwide research to overcome the significant technological challenges is culminating in the ITER experiment [1], currently under construction in Cadarache, France. In this, 50 MW of input heating is anticipated to output 500 MW of fusion power from a 150 million°C plasma sustained for up to 1,000 seconds, aiming to demonstrate the commercial potential of fusion power.
The materials used to construct such reactors are exposed to extreme conditions in terms of temperature, heat flow and plasma ablation as well as neutron irradiation. This is despite the highly sophisticated magnetic confinement of the fusion plasma used to shield the reactor's physical components and materials. The leading plasma facing material to withstand such temperatures is tungsten, the highest melting point metal. However, tungsten exhibits a brittle to ductile transition temperature (DBTT), and also suffers from irradiation embrittlement.
In this project new tungsten alloys with increased performance will be developed following two microstructural design concepts. Firstly, utilising two-phase microstructure to enable nano-scale grain refinement to improve ductility and fracture toughness. Secondly, utilising nano-scale grain boundaries and semi-coherent interfaces to act as sinks for irradiation damage. Such microstructures have been demonstrated within recently developed Ti ‘bcc superalloys' using β-β' TiFe [2], which are suggested to be possible for W within the W-Ti-Fe ternary system [3]. An alternative route is to use a two-phase miscibility gap as in W-Cr [4] or even within refractory metal ‘high entropy alloys' (HEAs) such as TaNbHfZr [5]. This project would produce new two-phase tungsten ‘bcc superalloys', characterise their microstructures and evaluate their mechanical properties as well as underlying deformation mechanisms.

The candidate will have a 1st class Undergraduate or Masters degree (or equivalent) in Materials Science, Mechanical Engineering, Physics or related discipline. A background in microstructural characterisation and/or mechanical testing would be advantageous.
Applications must be made through the university's on-line application system:
https://www.birmingham.ac.uk/postgraduate/courses/research/metallurgy-materials/metallurgy-materials.aspx?OpenSection=HowT
Please provide a cover letter summarising your research interests and suitability for the position; the contact details of two referees and a curriculum vitae. Please send a copy directly to Sandy Knowles.

Any question please contact Sandy Knowles: a.j.knowles@bham.ac.uk
http://www.birmingham.ac.uk/staff/profiles/metallurgy/knowles-alexander.aspx

Funding Notes

UKRI/EPSRC funded 3-year UK/EU PhD studentship with a stipend of £14,777 per year.

References

[1] www.iter.org
[2] https://doi.org/10.1016/j.scriptamat.2017.06.038
[3] https://doi.org/10.1016/0956-716X(93)90542-Z
[4] https://doi.org/10.1016/0001-6160(67)90352-5
[5] https://doi.org/10.1016/j.actamat.2016.01.018