Abstract

Metallic alloys are parvenus in the world of glasses, but they have recently been attracting much attention, and are very actively researched at present. Metallic crystal structures are simple, and metallic liquids have viscosities similar to water, so it is difficult to achieve the glassy state in metals; indeed it has traditionally been assumed that melt cooling rates of the order of 106 K s−1 are necessary. However, it has become clear that with well-tailored alloy compositions, rapid cooling is not necessary, and bulk metallic glasses (BMGs) can be made, for example as cylinders with a diameter of up to a few centimetres. Interestingly, the BMG -forming compositions can be very tightly defined, suggesting that these materials are akin to stoichiometric compounds, albeit with non-crystalline structure. They can also be anisotropic, as is being explored currently using the RUS facilities in the Dept. of Earth Sciences. The advent of BMGs has excited interest, and this presentation will review recent developments in understanding their formation, their atomic-level structure and its relaxation, and their elastic and mechanical properties. A recurring theme will be that there are remarkably good correlations linking the properties of metallic glasses, and that these can usefully be put in the context of other classes of glassy materials.

“Metallic glasses… on the threshold” A. L. Greer, Materials Today 12 (2009) 14-22.

“A damage-tolerant glass” M. D. Demetriou et al., Nature Materials (February 2011), available though advance online publication.