SAMUEL ARMSON
PhD Student - University of Manchester
Project Title: The importance of grain nucleation versus growth in the evolution of oxides formed on zirconium alloys
Samuel Armson completed his undergraduate degree in physics at the University of Leeds before embarking on a PhD in materials science with the Centre for Doctoral Training in Advanced Metallic Systems. This project is sponsored by Rolls-Royce plc and benefits from close collaboration with other universities and industrial partners thanks to its involvement in the MUZIC-3 programme (Mechanistic Understanding of Zirconium Corrosion).
Sam’s work focusses on using an array of advanced microscopy techniques to analyse the microstructure of zirconium oxide formed during corrosion. The comparison of grain sizes, grain shapes, and crystallographic orientations between oxides which have formed on different alloys and in different environments provides crucial insight for developing a better understanding of the corrosion behaviour of zirconium components. In particular, Sam is interested in looking at the effects of irradiation on oxide grain nucleation and overall corrosion rates. In order to explore these effects, in-situ irradiation-corrosion experiments using the particle accelerator at the Dalton Cumbrian Facility are under the final stages of development.
Alongside irradiation effects, this project also explores other factors which can contribute to poorer corrosion performance and enhanced oxide grain nucleation. These include the effects of Li additions to coolant water and the crystallographic texture of the fuel cladding. The latter of these studies has recently been accepted for publication in the ASTM Zirconium in the Nuclear Industry Journal, entitled ‘The importance of substrate grain orientation on local oxide texture and corrosion performance in α-Zr alloys’. Briefly, this study has revealed that local variations in corrosion behaviour arise due to lattice matching between the growing oxide and metal grains with particular orientations.
From an industrial perspective, this project provides crucial information which can be included in models which predict fuel behaviour. This improvement in fundamental understanding will ultimately allow fuel vendors and plant operators to safely reduce conservative safety margins – thus extending fuel lifetime and overall efficiency.
Next Steps: Sam has successfully completed his PhD and now works as a Corrosion Scientist at Jacobs in the Northwest region, a role which keeps him connected with MIDAS activity. Some of Sam’s work was included in the recent Nature Communications publication from the MIDAS team Untangling competition between epitaxial strain and growth stress through examination of variations in local oxidation. .