David Dunand, James N. The and Mary M. Krebs, professor of Materials Science and Engineering Northwest, has collaborated with Peter Müllner, professor of materials science and engineering at Boise State, in a project centered on a nickel-manganese-gallium alloy that changes shape when exposed to a magnetic field.

The alloy retains its new shape when the field is off, but returns to its original shape if the field is rotated 90 degrees, which demonstrates “the magnetic shape memory.” The alloy can be activated million times, and is deformed so reliable and reproducible results. This property can be used to advantage in fast-running actuators (mechanical moving or controlling a mechanism or system) for inkjet printers, car engines and surgical tools.

To date, magnetic shape memory effect has occurred only in nickel-manganese-gallium single crystals, which are much more difficult and expensive to create than the more common polycrystals.

Now, Dunand, Müllner and his colleagues have developed the foam easily processed polycrystalline with a form of exchange of properties similar to those of the individual crystals much more expensive. They did so by introducing small pores in the “nodes” of its original metal foam, which, like a sponge, is composed of nodes connected by struts relatively large. Adding a second level of porosity allows deformation and polycrystalline foam retention of some of the properties of shape memory.

The results are published online by the journal Nature Materials.

“A key aspect of this new foam” smart “is that, along with a single coil to produce a magnetic field creates a linear actuator extreme simplicity – and both high reliability and miniaturization potential – the replacement of an electro much more complex mechanical system with many moving parts, “Dunand said.

Potential applications range from the replacement of the materials currently used in sonar devices, actuators and precision magneto-mechanical sensors to allow new devices in biomedicine and Microrobotics.

“This was an improvement so great that the foam has been proven time and again to ensure no experimental errors were made,” Müllner said. “Our new findings could pave the way for a magnetic memory alloys for use in research laboratories and commercial applications.”

Northwestern and Boise State have filed a patent application.

More information: The title of the Nature Materials is the “Giant magnetic field induced strains in polycrystalline Ni-Mn-Ga foam.