Liquid and amorphous metals: Current trends and future perspectives

• Published in: The European physical journal. ST, Special topics Special topics, 2011-05, Vol.196 (1), p.1-2
• Main Authors: Scopigno, T., De Panfilis, S., Di Cicco, A.
• Format: Article
• Language: English
• Subjects: Atomic; Classical and Continuum Physics; Communication, education, history, and philosophy; Condensed Matter; Condensed Matter Physics; Exact sciences and technology; Materials Science; Measurement Science and Instrumentation; Molecular; Optical and Plasma Physics; Other; Physics; Physics and Astronomy; Physics literature and publications
• ISSN: 1951-6355; 1951-6401
• DOI: 10.1140/epjst/e2011-01412-5

Liquid and amorphous metals are an outstanding example of systems combining great relevance in both industrial applications and basic science. They find broad technological application, ranging from the production of industrial coatings (walls of refinery cokers, drill pipes for oil drilling) to medical equipment (reconstructive devices, surgical blades) or high-performance sporting goods. Most metallic materials, indeed, need to be refined in the molten state before being manufactured. Liquid metals, in particular the monoatomic ones, have long been recognized as the prototype of simple liquids, in the sense that they encompass most of the physical properties of real fluids without the complications which may be present in a particular system. Until the sixties the understanding of the physical properties of liquid metals proceeded rather slowly. It was John Ziman, indeed, who first developed a theory for the electron transport in liquid metals in 1961, and subsequently several experimental and theoretical studies were presented at the first Liquid Metals International Conference held in Brookhaven in 1966 (see, for example, refs. [1-3]). From the experimental point of view, the 1950s saw major efforts related to the development of neutron scattering facilities, which constitute a unique probe in accessing the microscopic structure and dynamics in condensed matter and, in particular, in the liquid and amorphous state. A further experimental breakthrough, however, has happened in the last twenty years when X-rays generated by synchrotron radiation facilities could be used as a probe for structure and dynamics in frequency and wavelength regions similar to those explored by neutrons. Concerning the nature of the dynamical structure in liquid and amorphous metals, in the last two decades many theoretical and experimental groups have switched their studies to researching effects due to non-hydrodynamic processes in liquids, i.e. collective processes which cannot be predicted by ordinary hydrodynamics. Examples of such non-hydrodynamic propagating excitations are shear waves, the famous "fast sound" [4] in binary liquids with disparate masses, or charge waves in ionic melts [5], while the most obvious non-hydrodynamic relaxation process is structural