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John Hunt Medal

 

 

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John Hunt Medal

The John Hunt Medal is presented to an individual who has made an outstanding contribution to the science and/or technology of casting and solidification of metals. The award recognises the lifetime contribution of Professor John Hunt FRS and is supported by the General Research Institute of Non-ferrous Metals (GRINM) in Beijing.

John Hunt

Professor John David Hunt FRS

12 December 1936 – 8 December 2012

John Hunt was an eminent metallurgist who will be remembered as a pioneer in the field of solidification research.

John was born on 12th December 1936 in Cheltenham and soon moved to Dorset to a family farm where he spent a happy childhood with two elder sisters and a younger brother enjoying the freedom of the countryside and the challenges of farming. By the age of 9 he was already a member of the Young Farmers Club in Dorset and his bucolic childhood hugely influenced both his life-style and his pragmatic hands-on research career. John was educated at Wellington School in Somerset, where he was a key member of the School’s 1st XV Rugby Team and worked in the summer holidays as a beach photographer in Weymouth.

John earned his BA in metallurgy in 1960 and PhD in 1963 both from Cambridge University. His PhD thesis was titled “Modification of Eutectics”. John then joined the Bell Telephone Laboratory at Murray Hill, New Jersey as a research fellow for two years and then the UK Atomic Energy Authority at Harwell for one year. He was appointed as a lecturer at Oxford in the Department of Materials Science in 1966 and a Fellow and Tutor in Metallurgy in St Edmund Hall in 1968. He was made an Ad Hominem Reader in 1990, a University Professor in 1996, an Honorary Professor of North Western Polytechnic University in China in 1996, and retired, aged 67, in 2004. Then, in 2006, John became a Professor Associate in BCAST at Brunel University, where he continued his solidification research with great passion.

John was an inspiring and deeply insightful teacher and his lectures on solidification and chemical metallurgy were well remembered by his students due to his unique approach to their delivery. He often started his lectures with a precise definition of a problem, followed by the introduction of the existing theories as potential solutions, but always ended up explaining why the existing theories were wrong. This left his students with a huge urge to solve problems and inspired them to become key players in solidification research.

John had an unusual ability to see through complex natural phenomena and to develop simple physical and mathematical solutions. Through his natural instinct and deep insight, every challenge became easy and simple to him. It was repeatedly demonstrated that his assumptions or simple models could not be improved or bettered. He could often surprise colleagues with an immediate answer within the right order of magnitude. He was well known for his no-nonsense comment at conferences of “I don’t believe it!” which inspired colleagues to go the extra mile for better answers and solutions. This made John the major contemporary personality of solidification research and won him great respect from his peers.

John’s scientific achievements in the field of solidification are extensive, deep and pioneering. With Ken Jackson he discovered transparent low melting point materials as analogues for metallic materials solidification and the widely used eutectic growth model. With his research group at Oxford, John developed the first self-consistent model of cellular and dendritic growth, the first realistic model of columnar equaixed growth and the theoretical models for selection of the eutectic range. John’s experimental research was also very fruitful. He developed the only method for direct measurement of solid/liquid interfacial energy, in situ observation and modelling of porosity formation in aluminium, a new mechanism for particle pushing during solidification, development and modelling of the twin roll casting process and a new single pan high resolution calorimeter. As mentor to the BCAST group at Brunel University, he actively participated in their research activities related to liquid metal engineering and the development of the epitaxial nucleation model and the fully equiaxed solidification model.

John met Ann during their first year as undergraduates in Natural Sciences at Cambridge and they married in 1961 and celebrated their Golden Wedding on the River Thames in September 2011. John and Ann moved to the Church Farm House in North Leigh in 1968 and lived there for the next 44 years, where John ran a well maintained vegetable patch in their huge garden and kept ducks, geese, and pigs. John made a temperature and humidity controlled incubator to hatch the eggs. The Hunt family were kept fed with duck, goose and pork dinners with garden grown vegetables and homemade cider. They ate what they bred and drank what they brewed, and John’s students greatly benefited from this farming tradition as John and Ann had an open day each term for them at the Church Farm House. This open day became a village tradition after his retirement.

John published over 200 research papers and received recognition and honours from many quarters. He was elected Fellow of the Royal Society in 2001. He received the Champion Herbert Mathewson Gold Medal from the American Institute of Metallurgical Engineers (AIME) in 1967, the Rosenhain Medal and Prize from the Institute of Metals in 1981, the Bruce Chalmers Award from TMS and AIME in 1996, and the Royal Society and Armourers and Brasiers’ Company Medal and Prize in 2001. John’s outstanding contribution to solidification research was honoured by a symposium and dinner as part of the TMS Spring Meeting in San Antonio in March 2006, and the John Hunt International Symposium was held at Brunel University in 2011 on John’s 75th birthday to celebrate 50 years solidification research.

John Hunt died peacefully on 8th December 2012 and is survived by Ann, their two children, David and Helena, and their five grandchildren. He will be fondly remembered as a loving family man, a remarkable person and an outstanding scientist.

Respectfully submitted, Z. Fan, BCAST, Brunel University.

John Hunt Memorial Lecture 2018 - Abstract

Solidification of metals: interest and importance across the full range of supercooling

A. L. Greer

University of Cambridge, Department of Materials Science & Metallurgy, 27 Charles Babbage Road, Cambridge CB3 0FS, UK.

This presentation will focus on those aspects of my work that have most connection with the seminal contributions of John Hunt on solidification of metals ― in fundamental understanding of mechanisms (the heterogeneous nucleation of crystallization); in technological relevance for the processing (the columnar-to-equiaxed transition, CET, and grain refinement); in microstructural control (pattern formation, and property optimization); and in technique development (calorimetry).  John Hunt did not work on the glassy state in metals, yet it is relevant for his areas of interest.

Heterogeneous nucleation of the crystallization of liquid alloys can be better understood from transmission electron microscopy studies of the onset of crystallization on substrates within a metallic glass, the glass acting as a slow-motion analogue of the liquid [1].

The nucleation of grains in an inoculated alloy is critical in understanding the CET and grain refinement.  The ‘free-growth model’ [2] is now widely accepted as a basis for quantitative analyses:  it is supported by recent in-situ observations [3]; and is also relevant for very different cases such as ice-nucleating agents and the freeze tolerance of living systems [4].

Crystallization on rapid cooling, or on annealing of an ‘overquenched’ glassy alloy, can give nanocrystalline products with outstanding mechanical properties [5].  Recent results on this aspect of microstructural control give insight on the origin of these properties [6].

Ultra-fast heating of glasses permits useful extension of earlier calorimetric studies of the heating-rate dependence of crystallization rates [7], and permits studies of the liquid fragility.  Ultimately such studies may lead to the application of the solidification of metals in computer memory [8].

[1] P Schumacher et al., New studies of nucleation mechanisms in Al-alloys:  implications for grain-refinement practice, Mater. Sci. Technol. 14 (1998) 394‒404.
[2] AL Greer et al., Modelling of inoculation of metallic melts:  Application to grain refinement of aluminium by Al-Ti-B, Acta Mater. 48 (2000) 2823‒2835.
[3] Y Xu et al., Revealing the heterogeneous nucleation behavior of equiaxed grains of inoculated Al alloys during directional solidification, Acta Mater. 149 (2018) 312‒325.   
[4] Nucleation in Condensed Matter:  Applications in Materials and Biology, KF Kelton & AL Greer.  Elsevier, Amsterdam (2010), pp. 630‒633.
[5] ZC Zhong et al., Microstructure and hardening of Al-based nanophase composites, Mater. Sci. Eng. A 226-228 (1997) 531‒535.
[6] HW Bi et al., Novel deformation-induced polymorphic crystallization and softening of Al-based amorphous alloys, Acta Mater. 147 (2018) 90–99.
[7] J Orava et al., Characterization of supercooled liquid Ge2Sb2Te5 and its crystallization by ultra-fast-heating calorimetry, Nature Mater. 11 (2012) 279‒283.
[8] AL Greer, New horizons for glass formation and stability, Nature Mater. 14 (2015) 542–546.

 

Prof. A. Lindsay Greer - Biography

Professor of Materials Science. University of Cambridge, Cambridge UK.

Lindsey Greer_web

At the University of Cambridge, Lindsay Greer is Head of the School of the Physical Sciences, and was (2006‒2013) Head of the Department of Materials Science & Metallurgy. He received his MA and PhD degrees from Cambridge, and holds an Honorary Doctorate from AGH University of Science & Technology, Cracow, Poland. He was a NATO Research Fellow and Assistant Professor of Applied Physics at Harvard University, and has held visiting positions at the CEA and INP Grenoble, Washington University (St Louis), and the Universities of Vienna and Turin. He is a Foreign PI of the Advanced Institute for Materials Research, Tohoku University (Sendai, Japan). 

Prof. Greer’s research interests include chalcogenide thin films for phase-change data storage, and the fundamentals of crystal nucleation and growth in liquids and glasses. He holds an ERC Advanced Grant for research on metallic glasses; this focuses on extending the range of glassy states that can be achieved, with differing degrees of heterogeneity.