Metallic glasses are promising materials for structural engineering, but their poor ductility makes them brittle, limiting their applications. Researchers in China have now shown that these glasses can be made much softer by reducing their size down to the microscale.

As their name implies, metallic glasses have the properties of both metals and glasses – they contain metallic bonds and are thus conducting, but their atoms are disordered like in a glass. These metastable materials are produced by rapid quenching from the liquid state and their physical properties depend on how they have been processed. They can be made more plastic to some extent by applying stress or high temperatures, but the effect – which is related to structural disordering in the material – is limited.

Researchers led by Bao-An Sun and Hai-Yang Bai of the Institute of Physics at the Chinese Academy of Sciences in Beijing are now reporting on a marked “rejuvenation”, or softening, of metallic glasses that have been drawn while still hot into micron-sized wires. Compared to their bulk counterparts, the modulus and hardness of these wires are much lower, decreasing by 26% and 17%, respectively.

“Such pronounced rejuvenation is unusual for metallic glasses,” explains Sun, “with previous studies reporting on only a few percent decrease in modulus and hardness.”

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