New atomic structure

A team from the University of Wisconsin-Madison and Iowa State University used powerful computational tools and state- of-the-art scanning transmission electron microscope to make the discovery. The researchers say the findings would fill a gap in understanding of this atomic structure. This understanding ultimately could help manufacturers fine-tune such properties of metallic glasses as ductility, the ability to change shape under force without breaking, and formability, the ability to form a glass without crystallising. Glasses include all solid materials that have a non- crystalline atomic structure: They lack a regular geometric arrangement of atoms over long distances. "The fundamental nature of a glass structure is that the organisation of the atoms is disordered-jumbled up like differently sized marbles in a jar, rather than eggs in an egg carton," team leader Paul Voyles said in a release. It's widely believed that atoms in metallic glasses are arranged only as pentagons in an order known as five-fold rotational symmetry. However, in studies of a zirconium-copper-aluminum metallic glass, the team found there are clusters of squares and hexagons -- in addition to clusters of pentagons, some of which form chains -- all located within the space of just a few nanometres, the 'Physical Review Letters' reported. "One or two nanometres is a group of about 50 atoms -- and it's how those 50 atoms are arranged with respect to one another that's the new and interesting part," he said. For Voyles and his team, the next step will be to calculate the properties of the most realistic structural models of metallic glass they have developed to learn how those properties relate to the structure.