Comparison of transduction behavior of polycrystalline gallium-iron alloys and Terfenol-D

This investigation focused on dynamic characterization of a laminated polycrystalline sample of Fe81.6Ga18.4 alloy grown by the FSZM process. Previous studies using static characterization methods have shown unique properties of the alloy for use in transducers and active structures. Static characterization values were verified and material properties were contrasted with the "giant" magnetostrictive material Terfenol-D. Common test methods were used for dynamic characterization to calculate Young's modulus, coupling coefficient, magnetostrictive coefficient, and permeability. In addition, mechanical Q and potential efficiency were calculated. Comparison with static testing of single crystal samples showed that modulus, permeability, and magnetostrictive coefficient were very close to static values, with any differences being attributed to test fixture effects and material differences. Coupling coefficient appeared to be quite low, but no correction was applied for the test fixture losses and magnetic circuit effects. Comparisons with Terfenol-D show that with significantly less magnetic field, iron-gallium alloys can be used in high Q systems to achieve large acceleration and force output. The unique structural and magnetic properties of gallium-iron alloys enable applications that would be difficult or impossible with Terfenol-D.