The Discovery of Amorphous Metals

21 Dezember

Closely linked to the basic research on the glass state itself is the early history of metallic glasses. As part of his pioneering work on the supercooling of melts, the physician David Turnbull predicted in the 1950s that, in principle, any liquid could be cooled to the glass state if only its viscosity would decrease fast enough with temperature. Metals, with their particularly unfavourable properties for glass formation, were considered the touchstone of this idea.

The first amorphous metal was produced in 1960 by Paul Duwez at the California Institute of Technology. He used an alloy of gold and silicon in a ratio of 3:1, very close to the eutectic point (19 % silicon). Compared to pure gold, the melting point here is significantly lower, at only about 500°C (for comparison: pure gold melts at 1063 °C). Despite relatively low temperatures, the alloy remains liquid and thus favours glass formation. Although Duwez cooled his samples with more than one million Kelvin per second, his material only reached a thickness of less than 50 micrometres.

As early as 1976, H. Liebermann and C. Graham developed a technique in which cooled rollers could be used to produce long strips of amorphous metals quickly and cheaply. This led to the commercialisation of the first metallic glasses in 1980 under the trade name Metglas. This material was used in the form of magnetic strips in an anti-theft system.