‘Superelastic’ alloy could help buildings resist earthquakes

Materials scientists at Tokyo University have developed a ‘superelastic’ metal alloy that can resume its original shape after deformation even over a wide range of temperatures.

The alloy could be used in the supporting beams of tall buildings to make them more earthquake resistant.

Superelastic alloys are metals that revert naturally back to their original shape after being bent or deformed by outside forces once those forces are removed, and are generally created by mixing two or more other metals together in certain combinations.

The reason that superelastic alloys are able to revert to their prior shape is due to their unique crystal structure, which allows the atoms to shift as a force is applied; as opposed to regular metals, where the force is diffused through the crystal structure, changing its composition.

Superelastic alloys are used in many applications, such as eyeglasses, antennas, and medical tools and equipment.

Prior to the current work, such alloys were only able to revert to their original shape between the range of -20 to 80°C. 

‘The stress increases with increasing temperature, which limits the practical use over a wide temperature range,’ said project lead Toshihiro Omori and co-workers reporting the findings in the the journal Science.

The researchers added a small amount of nickel to an iron-based alloy and found that the new material could recover its original shape at any temperature from -196 to 240°C.

The material could be used in environments that are constantly exposed to extreme temperatures, such as joints and controls in cars, aircraft and spacecraft.