Smart Foam

Researchers have made a lighter and potentially cheaper kind ofshape-memory alloy: materials that change shape in response to amagnetic field but remember their original shape. The new material, aporous foam made from a nickel-manganese-gallium alloy, stretchesslightly when exposed to a magnetic field. It retains its new form whenthe field is turned off, but it goes back to its original shape whenthe field is rotated 90 degrees.

Magnetic shape-memory alloys have been difficult and expensiveto make. The new alloy could be cheaper and easier to synthesize.

And it could be useful in devices that need very precise, repeatable, and rapid positioning, says David Dunand, a materials-science and engineering professor at Northwestern University. Dunand led the work on the new alloy with Peter Mullner,an associate professor at Boise State University. These devices includemicroscopes, tiny mirrors used in optical communication, and robotsused in medicine. Because the foam is light, it could lead to aerospaceapplications, such as airplane wings that morph to become moreaerodynamic.

Source: technologyreview.comAdded: 1 February 2008