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Friday, February 19, 2010

Build with super strong nanopillars

Julie Greer and Dongchan Jang, both from the California Institute of Technology (Caltech), have devised a novel set of materials with great strength and flexibility. How did they do this? By making things smaller….much smaller.

The building materials in use today all have advantages and disadvantages. Ceramics are very strong, but heavy and brittle. Metals can be pliable, but aren’t as strong as ceramics. One promising class of materials are called ‘glassy metallic alloys’. Glass is an amorphous solid material. In other words, glass is a material that has been cooled to its solid state without crystallizing, but instead while maintaining the liquid-like flow of atoms.

Like glass, glassy metallic alloys are also amorphous, non-crystalline solids, but containing metallic elements such as zirconium, titanium, copper, or nickel. Like true metals, they’re lightweight, and like ceramics they’re very strong. Unfortunately, also like ceramics and regular glass, they are extremely brittle.

In order to circumvent this problem, Greer and Jang designed ‘nanopillars’ of zirconium-rich glassy alloy only 100 nanometers in diameter (for reference a human hair is about 100 micrometers across). Surprisingly, these tiny pillars were both ductile and strong, making them excellent building materials. Or at least, they would be if anyone could figure out how to combine them into normal sized structures.

Greer is confident that this will happen soon:

Our findings provide a powerful foundation for utilizing nanoscale components, which are capable of sustaining very high loads without exhibiting catastrophic failure, in bulk-scale structural applications specifically by incorporating architectural and microstructural control.


Scanning electron micrograph of a 100-nm-diameter tensile sample. (Credit: Dongchan Jang/Caltech).