CHARACTERIZATION OF TERFENOL-D FOR MAGNETOSTRICTIVE TRANSDUCERS

Measurements were made of the piezomagnetic d33 coefficient, the free permeability, mu-33T, and the open-circuit elastic compliance coefficient, S33H, of grain-oriented Terfenol-D, Tb0.3 Dy0.7 Fe1.93, produced by a modified Bridgman technique. Prestress levels to 9500 psi (65 MPa) and magnetic bias fields up to 2200 Oe (175 kA/m) were applied with a laboratory electromagnet modified so that one pole piece served as a hydraulically actuated piston. The results indicate that d33, mu-33T, and S33H are dependent on stress and magnetic field, so that proper mechanical prestress and magnetic bias conditions are critical to the successful use of Terfenol-D in transducers and actuators. Radiated-power limits for underwater acoustic projectors are estimated and compared with those for projectors having lead zirconate titanate (PZT-4) piezoelectric drivers. Terfenol-D based transducers can be as much as 8 dB superior to PZT-4 under low-Q, field-limited conditions (Q = mechanical quality factor).

对采用改进的布里奇曼技术生产的晶粒取向的Terfenol - D（Tb₀.₃Dy₀.₇Fe₁.₉₃）的压磁d₃₃系数、自由磁导率μ - 33T以及开路弹性柔顺系数S₃₃H进行了测量。使用经过改装的实验室电磁铁施加高达9500磅力/平方英寸（65兆帕）的预应力水平和高达2200奥斯特（175千安/米）的偏置磁场，其中一个磁极片用作液压驱动活塞。结果表明，d₃₃、μ - 33T和S₃₃H取决于应力和磁场，因此适当的机械预应力和磁偏置条件对于Terfenol - D在传感器和执行器中的成功应用至关重要。对水下声发射器的辐射功率极限进行了估算，并与具有锆钛酸铅（PZT - 4）压电驱动器的发射器进行了比较。在低Q（机械品质因数）、场受限条件下，基于Terfenol - D的传感器可比PZT - 4优8分贝。