Particle size effect on the complex permeability for permalloy composite materials

Complex permeability μ*(=ν\´-iμ") of permalloy (Fe_0.55Ni_0.45) composite materials has been studied in the frequency range from 10 kHz to 2 GHz for two different particle sizes of permalloys (particle diameter d<45 μm and d<6 μm). Low frequency permeabilities of small particle composites have larger values than those of large particle ones and natural resonance frequency of small particle composites is lower than that of large particle ones. The ac electrical resistivity in low frequency range shows a drastic increase at about 40 vol% permalloy content with decreasing permalloy content indicating the disconnection of embedded permalloy particles. These properties can be realized considering the eddy current in composite materials