Professor of Materials Science
MA University of Cambridge
PhD University of Cambridge
My interest is in how materials change their structures. Understanding the mechanisms of these transformations is relevant not only for assessing the stability of materials, but also for developing new microstructures, properties and functionalities.
One route to new structures is to move further from equilibrium, and metallic glasses are a good example. Now that metallic glasses are available with minimum sections of the order of 1 cm, there is much interest in their mechanical properties, notably their exceptionally high strength, elastic strain and elastic energy-storage capacity. We focus on the mechanisms of plastic flow under ambient conditions.
Nucleation is the first step in phase transformations. Deliberate promotion of nucleation, whether in industrial processing such as metal casting, or the control of ice formation by living systems, remains imperfectly understood, but our recent work shows that the nucleation kinetics can be quantitatively predicted.
Chalcogenides for data storage
Chalcogenide alloys can be reversibly switched between glassy and crystalline states. This switching can be exploited in data storage (for example in phase-change RAM), but is also of interest in areas such as neuromorphic computing. Our research, challenging because of the ultra-short switching times, focuses on crystallization kinetics.
The control of microstructure in as-cast alloys is important in optimizing their properties. Our focus is on the use of grain refining agents (inoculants, see figure) to control grain size and phase dispersion, working mostly on light alloys (based on Al, Mg or Zn).
|X-ray tomograph of dispersed lead particles in an Al91Pb9 alloy cast with added Al-Ti-B inoculant.|
- KF Kelton & AL Greer, Nucleation in Condensed Matter: Applications in Materials and Biology, Elsevier (2010) ISBN: 978-0-08-042147-6. (726 pp)
- GN Greaves, AL Greer, RS Lakes & T Rouxel, “Poisson’s ratio and modern materials” Nature Mater. 10, 823–837 (2011).
- J Orava, AL Greer, B Gholipour, DW Hewak & CE Smith, “Characterization of supercooled liquid Ge2Sb2Te5 and its crystallization by ultra-fast-heating calorimetry” Nature Mater. 11, 279–283 (2012).
- AL Greer, YQ Cheng & E Ma, “Shear bands in metallic glasses” Mater. Sci. Eng. R 74, 71–132 (2013).