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 Fe80Ga20 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 Mössbauer spectroscopy. Results for the measured magnetic hysteresis loop (B–H curve), static magnetostriction (λ) versus applied field and dynamic relative permeability (μr33) 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 μr33 at a given applied magnetic bias field has been found to decrease with decreasing particle size.

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A three-fold coincidence arrangement of two scintillation counters and an optical Cerenkov counter was used to form a cosmic-ray muon momentum selection system of 0.21 sr cm2 aperture. The variation of pressure of the nitrogen gas in the Cerenkov counter enabled the cosmic ray muon momentum spectrum at sea level to be determined by the technique of threshold discrimination. The spectrum so obtained compared favourably with that determined by magnetic spectrography. The work presented in the paper formed part of a final-year undergraduate project undertaken by the authors.

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