Alloys of iron and non-magnetic gallium (of the form Fe1-xGax), collectively referred to as Galfenol, have been shown to exhibit magnetostrictions in excess of 300 ppm under quasi-static magnetic fields . However, to harness the full potential of this material as an actuator, characterization of Galfenol's magneto-mechanical properties under dynamic operating conditions is required. Broadband frequency domain results include strain per applied magnetic field transfer functions and complex electrical impedance functions. The properties investigated were linear mechanical rod stiffness, magneto-mechanical coupling coefficient, modulus of elasticity, and system structural damping. The samples tested were single-crystal cylindrical Galfenol rods with an atomic percentage of Gallium varying from 18 to 22.5. Some rods were composed of laminated strips of Galfenol to reduce eddy current effects and increase the efficiency of transduction. It was found that lamination did not significantly degrade the stiffness nor increase the structural damping, but did increase the magneto-mechanical coupling coefficient by ~50% over the solid rod for the conditions studied.
Alloys of iron and non-magnetic gallium (of the form Fe1-xGax where x ranges from 13 to 30) exhibit large magnetostrictions of over 300 ppm at room temperature that are produced by saturation magnetic fields of approximately 600 Oe. While not producing magnetostrictions of the degree achievable with giant magnetostrictives, large magnetostrictive alloys of iron and gallium, called Galfenol, have much more desirable mechanical characteristics, such as non-brittleness and in-plane auxetic behavior. Additionally, Galfenol requires a much smaller saturation magnetic field than the giant magnetostrictives Terfenol and Terfenol-D (alloys of Iron and non-metallic Terbium and Dysprosium). Beginning from the body of knowledge gained from Terfenol and Terfenol-D dynamic research transducer designs is a good starting point for designing a Galfenol dynamic research transducer. However, several modifications are being made to adapt the transducer to some of Galfenol's unique properties. Any measured value uncertainty will quickly propagate through the calculated material properties. While not completely successful at addressing all the unique aspects Galfenol in this transducer design, the data presented will assist in future design attempts.