Organized by the Institute of Experimental Physics, University of Bialystok and the Institute of Atomic Energy, Swierk under the auspices of the European Crystallographic Association; Committee of Crystallography, the Polish Academy of Sciences; and the Polish Neutron Scattering Society The School is financially supported in part by the International Union of Crystallography; the European Crystallographic Association; the European Office of Aerospace Research & Development; the Ministry of Science and Information Society Technologies; the Warsaw University of Technology; and the University of Bialystok.
		The avoidance of crystallization during cooling of metallic melts Hywel A. Davies University of Sheffield, UK Topics Metallic glasses are now a well-established class of materials, with applications, in thin ribbon form, for many types of magnetic devices such as power and high frequency transformers and as cores for inductors, chokes and earth leakage protectors. In the form of thin wire, they also find applications for stress and magnetic field sensors and for giant magneto-impedance devices. Until relatively recently, almost all glassy alloys, synthesised by continuous cooling from the liquid state, could only be produced in thin sections less than ~100 mm, since the critical cooling rates required for their formation Rc are very high, typically >~105 K/s. The reason for this is principally because metallic melts, in contrast to covalently bonded liquids such as silicates and borates etc., are highly fluid at their equilibrium freezing temperatures. However, over the last decade an increasing range of alloy compositions has been identified as having much lower Rc, such that they can be synthesised in much greater section thicknesses than previously, in some cases 50mm and greater. These offer promise of a more extensive diversity of potential applications, for instance, as structural components, because of the extraordinarily high intrinsic strength and hardness, combined with adequate toughness in some modes, of the non-crystalline structure. The kinetics of metallic glass formation are governed by the kinetics of crystal nucleation and, for practical purposes, of crystal growth. Satisfactory kinetic models were developed earlier to account, at least on an order of magnitude basis, for the wide range of observed glass forming abilities, with Rc spanning from ~1010 K/s down to ~102 K/s. However, the recent evolution of so-called bulk glass forming alloys has introduced new challenges for arriving at a satisfactory model to describe their very high glass forming abilities. This paper will briefly review our current understanding of glass formation in metallic alloy systems and the degree to which the kinetics of formation can be rationalised in terms of the structures and thermodynamic and other properties of the liquid and crystalline phases.