Switching strength on or off

A material has been designed to switch back and forth between a strong, brittle state and a weak, ductile one.

Hai-Jun Jin at the Chinese Academy of Sciences in Shenyang and Jörg Weissmüller at the Technical University of Hamburg in Germany made their composite by imbibing nanoporous gold (pictured) with an electrolyte. When the applied electrical potential shifted, the material showed distinct and reversible changes in strength, flow stress and ductility.

Although the exact mechanism remains unknown, the authors think that the adsorbed anions may be slowing down the movement of inherent defects at the surface of the nanoporous gold, enhancing the material's strength. They anticipate the development of a material that can be made ductile during moulding or fabrication, and tuned to the strong state when desired.

Credit: SCIENCE/AAAS

Science 332, 1179–1182 (2011)