High frequency magnetic properties of polymer-bonded Terfenol-D composites

We measure the high frequency magnetic properties of polymer-bonded Terfeno l-D rods compacted from powders of different size, in order to analyze the effect of structure and preparation conditions in sonic or ultrasonic frequ ency applications. Magnetic characterization at high fields and in the kilo hertz range is made using a custom built amorphous metal yoke. Experimental data are analyzed using the theory of losses and the dynamic Preisach mode l. The electrical resistivity is estimated to be about 1.25 mu Omega m, hig her than in grain-oriented materials. The classical contribution to dynamic power loss, directly proportional to conductivity, is found to be dominant . The analysis establishes a direct connection between static and dynamic m agnetic properties and structural characteristics, such as the density, con ductivity, and the powder size, which can be modified for optimization purp oses. (C) 1999 American Institute of Physics. [S0021-8979(99)21308-4].