Select your localized edition:

Close ×

More Ways to Connect

Discover one of our 28 local entrepreneurial communities »

Be the first to know as we launch in new countries and markets around the globe.

Interested in bringing MIT Technology Review to your local market?

MIT Technology ReviewMIT Technology Review - logo

 

Unsupported browser: Your browser does not meet modern web standards. See how it scores »

Making the foam is cheap and easy. The researchers pour molten alloy into a porous piece of sodium aluminate salt. After the alloy cools, the researchers dissolve the salt using acid, leaving behind a spongelike structure of the alloy. “The foam is a quite promising preparation route–significantly more efficient compared to the growth of single crystals,” says Sebastian Fahler, who studies shape-memory alloys at the Leibniz Institute for Solid State and Materials Research, in Dresden, Germany. But the shape change will have to be much higher than 0.12 percent to have practical applications, he says.

Dunand and his colleagues have a plan for increasing the foam’s shape change. Just like a sponge, the foam has struts connected at nodes, he explains. Each strut right now contains multiple tiny crystals. These crystals are still canceling out each other’s motion to some extent, which is why the overall change in the foam is only 0.12 percent.

To get a larger shape change, Dunand says, the trick will be to make each strut behave like a single crystal, so that the foam on the whole will be more like a single crystal. That means the researchers would have to make individual crystals span each of the struts in the foam.

The material will still face competition. Nickel-titanium shape-memory alloys, which are suitable for use inside the body and are driven by temperature, are already employed to make stents.

For micropositioning applications, says O’Handley, the material will have to compete with piezoelectric materials such as quartz and lead titanate, which deform in response to electric current. But because the process to make the foam is easy and cheap, he says that it brings nickel-manganese-gallium closer to being cost competitive with piezoelectric materials.

0 comments about this story. Start the discussion »

Credit: P. Mullner, M. Chmielus, and S. Donovan, Boise State University, and D. C. Dunand and Y. Boonyongmaneerat, Northwestern University

Tagged: Communications, Materials

Reprints and Permissions | Send feedback to the editor

From the Archives

Close

Introducing MIT Technology Review Insider.

Already a Magazine subscriber?

You're automatically an Insider. It's easy to activate or upgrade your account.

Activate Your Account

Become an Insider

It's the new way to subscribe. Get even more of the tech news, research, and discoveries you crave.

Sign Up

Learn More

Find out why MIT Technology Review Insider is for you and explore your options.

Show Me