Materials scientists at the U.S. Department of Energy’s Ames Laboratory,
Etrema Products Inc. (EPI), and the Naval Surface Warfare Center Carderock
Division have developed new ways to form a high-tech metal alloy which promise
new advances in sensing and energy harvesting technologies.
To look at it, a length of wire fabricated in the Ames
Laboratory looks much like the kind of steel wire a do-it-yourselfer could pick
up at the local hardware store. A sheet form of the material, fabricated by
EPI, looks equally unassuming. But these materials are made of a high-tech
alloy called Galfenol, and the new forms of this “smart material” may be the
key to future manufacturing breakthroughs like the creation of vibration free,
quieter motors.
Galfenol, composed primarily of gallium and iron, was
co-discovered in 1999 by the Ames Laboratory and the Naval Surface Warfare
Center Carderock Division. Galfenol’s unique properties make it change shape
when subjected to a magnetic field, and flexible enough for a variety of
manufacturing processes.
The three organizations spent a decade designing the alloy,
optimizing its properties and developing production processes. Now, they have
perfected methods of producing the material in rolled sheet and in wire form,
making it possible to use Galfenol-based smart parts in a variety of new
applications, especially vehicle technologies, both commercial and military.
“Galfenol exhibits a unique set of material properties that
allow us to process it using conventional rolling and wire drawing equipment
while at the same time we can develop the anisotropic magnetic properties that
we desire,” says Eric Summers, vice president and chief scientist of EPI. “In
addition, we can machine Galfenol using standard mills and lathes and weld it
to a variety of other materials. I know of no other current smart material that
shows this flexibility in processing.”
Tom Lograsso, director of the Division of Materials and
Engineering Science at Ames Laboratory, says the project was built on the
collaborative success of the giant magnetostrictive material, Terfenol-D. The
goal was to find an alloy with similar properties to Terfenol-D, which changes
shape when subjected to a magnetic field, but not as brittle.
“Terfenol is like glass. If you drop it on the floor, it
shatters. It also can be very prone to corrosion. Galfenol bounces if you drop
it; it can be machined; it can be welded. That has generated some new ideas
about how to use this material,” says Lograsso.
Galfenol can be used as a vibration-based energy-harvester;
attached to a vehicle motor it could supply power to the large number of
sensors present on a vehicle. The material could also be used to supply power
to wireless sensor networks via the same energy harvesting capability. The
combination of magnetic and mechanical properties could lead to the development
of active motor mount technology—creating an environment that actively senses
and cancels out motor vibrations, effectively creating a “silent” motor.
“Galfenol is receiving strong interest in the energy
harvesting community worldwide. Several companies are developing prototype
devices based on Galfenol technology as the power conversion component; the
core technology in a vibration-based energy harvester,” says Eric Summers of
EPI.
Source: Ames Laboratory
