NONDESTRUCTIVE EVALUATION OF TERFENOL-D FOR TRANSDUCER APPLICATIONS

A method and techniques have been developed for the nondestructive eva luation of grain oriented highly magnetostrictive rare-earth compounds , such as Terfenol-D, for use in actuator construction. Detection of a n asymmetric flux distribution and localized fluctuations in ac permea bility have been correlated with gradients in chemical composition and departures from the ideal grain structure produced by free float or c ontained zone preparation techniques. The data provide valuable inform ation to gauge material quality, the response of individual samples to applied stress, and the reproducibility of transducer properties from one sample to another. (C) 1997 American Institute of Physics.