Machine Design

Metal alloys with nanosized particles could be springier

Rutgers University

New metal alloys could make components more energy efficient and longer lasting. The metals, called decomposed two-phase nanostructured alloys, were discovered by researchers at Rutgers University.

The alloys form when metals cool from high temperatures and their internal structure divides into two phases. Each phase has its own crystal structure; one phase dominates the alloy while the other forms nanosized particles scattered throughout the alloy. Each phase reacts differently to stress, letting the metal deform when force is applied then spring back to its original dimensions after the force is removed.

The alloys can be piezoelectric or magnetorestrictive, converting movements into electrical or magnetic energy, respectively. They can also be made to move in response to electric currents or magnetic fields.

Materials that exhibit this behavior are called functional materials. In the case of these alloys, applying a magnetic or electrical field realigns the crystal structure of the nanoscale phase which deforms the rest of the alloy.

The researchers expect the alloys will have larger deformation and higher output force than current piezoelectric and magnetorestrictive materials with less energy input. And they believe the alloys’ properties can be tweaked by varying the ways they are processed.

The alloys’ elasticity may also be useful in mechanical applications. Blood-vessel stents, for instance, must remain springy throughout the life of the patient; they can’t exhibit hysteresis. The new alloys’ ability to spring back after deformation could fit that bill. And it may make them more energy efficient in piezoelectric and magnetorestrictive applications, as well, because they won’t require energy to reverse deformation.

So far, much of the Rutgers research has been based on computer simulation. The team hopes to test their theories on physical samples soon.

© 2011 Penton Media, Inc.

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