The Processing and Bulk Properties of New Low-Activation High-Entropy Alloys (materials strand project)

Supervisor/s – Dr Ed Pickering & Dr Aneeqa Khan (University of Manchester). Dr Huw Dawson (CCFE).

A number of existing alloys have been proposed for use inside future fusion reactors, including in the plasma-facing components that experience the most challenging conditions. However, there remains a real possibility that these alloys are not suitable for use in such environments, since they have not been tested under the extreme conditions they will face (a high flux of 14 MeV neutrons and temperatures above 500˚C). Hence, there is a strong argument that new fusion-focussed alloys be designed and investigated to maximise our chances of a successful outcome.

High-entropy alloys are a relatively new class of alloys that have generated a lot of interest in the materials science community over recent years. Instead of being based around one principal alloying element (e.g., Fe in steels), they comprise multiple elements in high concentrations. This design philosophy has opened up a huge range of alloy compositions that have not been explored before. Some work has been started on designing low-activation HEAs for fusion, i.e., alloys are less likely to become radioactive for a long period of time following exposure to fusion reactor conditions (and hence won’t have to be deposed of as long-life radioactive waste) [1-2].

This project will ‘scale-up’ work on new low-activation HEA compositions that have already shown some promise, with particular focus on the VCrMnFeAlx suite of alloys (where x varies between 0 and 1) [2]. These alloys have been shown to exhibit good thermal stability, and some also exhibit some interesting microstructures that could lead to high-temperature strength, see Fig. 1. However, to date these compositions have only been assessed using very small quantities of material, so their bulk mechanical properties (e.g., stress-strain curves, high-temperature properties) have not been measured. Neither have their responses to bulk thermomechanical treatments that might be used during their large-scale manufacture. Hence, this project will use larger castings (on the scale of a few kgs) to assess such properties. Advanced high-resolution characterisation techniques will be used alongside conventional mechanical testing.

Figure 1: High-resolution microstructure and elemental maps of VCrMnFeAl aged at 800 °C for 1000 hrs. The various regions of different composition (and structure) are all coherent with each other crystallographically [2].

The successful candidate will have a good undergraduate degree in a relevant subject, e.g., materials science, physics or engineering. Previous specialisation in metallurgy or fusion energy is not required as students will gain a broad understanding through the taught component of the CDT programme and through their preliminary research. This project will provide the opportunity to develop transferable skills and knowledge of industrial processes, metallurgy, irradiation damage, electron microscopy, and other analysis techniques, which should ensure the candidate is prepared for a wide range of possible career paths after graduation. Generic transferrable skills associated with programming, data manipulation and data interpretation will be gained.

[1]. P.J. Barron et al., Scripta Materialia 179 (2020) 12-16.
[2]. A.W. Carruthers et al., Journal of Alloys and Compounds (2022) in press.

The project will be based mainly in Manchester, but could involve short trips to international research institutions carrying out related work (such visits will be optional).

This project is offered by The University of Manchester. For further information please contact: Dr Ed Pickering (ed.pickering@manchester.ac.uk)

This project may be compatible with part time study, please contact the project supervisors if you are interested in exploring this.