Magnetic properties of epoxy-bonded iron-gallium particulate composites

摘要

This paper presents the production process and the results of investigations into the microstructure and magnetic properties of epoxy-bonded iron-gallium (Galfenol) particulate composites. The manufactured composites consist of powdered Fe_(80)Ga_(20) alloy particles of three different size distributions (ranging from 20 to 200 μm), bonded in an epoxy matrix with a filling factor of 0.80. The filling factor is defined as the ratio of the volume of Fe-Ga powder to the total volume of the composite's constituents. The microstructure of the powdered alloy has been examined using x-ray diffractometry (XRD), and M?ssbauer spectroscopy. Results for the measured magnetic hysteresis loop (B-H curve), static magnetostriction (λ) versus applied field and dynamic relative permeability (μ_r33) are presented for the alloy in the forms of bulk material, powders and composites subsequently manufactured. The highest value of magnetostriction (360 ppm) has been found in the composite with grain size in the range of 50-100 μm. On reversing the magnetic field direction, large magnetostrictive hysteresis for these samples has been observed. The value of μ_r33 at a given applied magnetic bias field has been found to decrease with decreasing particle size.