Giant magnetostrictive materials (GMMs) have large magnetostriction, but suffer from the disadvantage that eddy currents can flow easily in then. The frequency characteristics up to high frequency of a small sectional area were measured and compared by the powder metallurgy method and the Bridgeman method. This paper describes the following findings: (1) the powder metallurgy method is more useful in a low magnetic field, (2) permeability decreases rapidly to more than 10 kHz in a section with an area of 1 mm2, and (3) the displacement-magnetic field sensitivity decreases with the permeability, and has a resonance in the mechanical resonance frequency range.
