The Constants of Transformations

Paul Barron

Almost sixty years ago, David Edmonds met his friend for a coffee in the University of Birmingham  Students’ Union bar. This friend suggested that Edmonds, who had unsuccessfully applied to read  physics, should speak to the admissions tutor at the Metallurgy Department[1]. This chance exchange  set in motion a career which began with his doctoral studies, in which he researched zirconium-based  materials that were used to clad fuel rods in early nuclear fission reactors[2], and would eventually  leave an enormous mark on the world of metallurgy through his many discoveries on the phase  transformations of steels and other metals[3]. However, his impact, like the materials he worked with, has endured and adapted in no small part due to the work of his former students. 

Amongst them is Prof Sir Harry Bhadeshia, now also an internationally renowned figure in  metallurgical academia. Like his supervisor, Bhadeshia made many contributions to the understanding  of phase changes in steels[4]. One of his myriad discoveries was elucidating some transformation behaviour in nuclear reactor pressure vessels[5], a finding that will no doubt improve the lifetime of  both current and future reactors. This is just one example of how Bhadeshia’s work was driven by a  desire to improve important technologies using metallurgy[6]. Bhadeshia went on to supervise  doctoral students at the University of Cambridge (where I had the good fortune of being lectured by  him!), including Dr Ed Pickering, now my supervisor at the University of Manchester and already a  well-established metallurgist despite his relative youth. 

Pickering’s doctoral studies focussed on the changes that take place inside the massive ingots that are  forged into the same nuclear reactor pressure vessels that were a focus of his supervisor’s work[7].  After completing his PhD, Pickering’s academic work branched out into a more general study of phases  in other metals such as high-entropy alloys, a relatively new class of material that aims to exploit the  often-exceptional properties produced when many elements are mixed in roughly equal  proportions[8]. High-entropy alloys may offer a new direction for materials research in the field of  nuclear fusion. This forms the basis of my doctoral studies. 

Like my predecessors, I study how metals may change in the harsh environments inside nuclear  reactors. Although the materials and nuclear technology have changed, the motivations have not.  Understanding phase transformations in metals is key to improving them and the technologies that  rely on them, be it nuclear fission or fusion, or something else entirely. I believe it is this shared desire  to improve the world through better materials that unites the four of us. 

When searching for similarities in our research career, it can be easy to get carried away by grand  notions of a common goal, when it is often the small events in life that can be so important in  motivating someone. For instance, Bhadeshia stated in an interview that visiting his father’s battery  shop was what first piqued his interest in the scientific world[6]. This struck me as very similar to the  way trips to my grandfather’s machining workshop would kindle my curiosity about metals and how they could be hard yet malleable. Another curious commonality was Edmonds’ decision to pursue  metallurgy instead of physics, which was echoed by my own choice of specialising in materials science  after finding physics too difficult during undergraduate. All these motivating factors, grand and small,  have resulted in immense contributions to society by three distinguished academics. I can only hope  that my own career has even a fraction of their impact!

References 

[1] D. V. Edmonds, Personal communication. Nov 2020. 

[2] D. V. Edmonds and C. J. Beevers, “Some observations on discontinuous yielding in Zircaloy-2,” Journal of Nuclear Materials, vol. 28, no. 3. North-Holland, pp. 345–348, 01-Dec-1968. 

[3] J. G. Speer and H. K. D. H. Bhadeshia, “A tribute to Professor David V. Edmonds on the eve of  his retirement,” Mater. Sci. Technol. Conf. Exhib. 2009, MS T’09, vol. 3, pp. 1575–1590, 2009. 

[4] H. K. D. H. Bhadeshia and D. V. Edmonds, “The mechanism of bainite formation in steels,” Acta Metall., vol. 28, no. 9, pp. 1265–1273, Sep. 1980. 

[5] H. Pous-Romero, I. Lonardelli, D. Cogswell, and H. K. D. H. Bhadeshia, “Austenite grain growth  in a nuclear pressure vessel steel,” Mater. Sci. Eng. A, vol. 567, pp. 72–79, Apr. 2013. 

[6] British Library, “Harry Bhadeshia: life as a scientist,” Voices of Science, 2013. [Online].  Available: https://www.bl.uk/voices-of-science/interviewees/harry-bhadeshia/video/harry bhadeshia-life-as-a-scientist. 

[7] E. J. Pickering, “Macrosegregation in steel ingots,” University of Cambridge, 2014. 

[8] E. J. Pickering and N. G. Jones, “High-entropy alloys: a critical assessment of their founding  principles and future prospects,” Int. Mater. Rev., vol. 6608, no. May, pp. 1–20, 2016.