Magnetic and Microstructural Aspects of the Bulk Metallic Glassy Materials Nd₆₀Fe₃₀Al₁₀

Abstract

The ferromagnetic bulk metallic glass (BMG) Nd₆₀Fe₃₀Al₁₀system exhibits extremely large coercivities at low temperature and moderate coercivities near room temperature. The magnetic hardness, as best evidenced by the onset of magnetic irreversibility, was studied in bulk suction-cast and melt-spun alloys with the nominal composition Nd₆₀Fe₃₀Al₁₀. Systematic x-ray diffraction studies of the degree of crystallinity performed as a function of position within the bulk suction-cast samples is found to correlate with the variation in the room-temperature magnetic hysteresis character. X-ray diffraction data clearly shows the presence of both crystallites and amorphous material on the samples’ outmost surfaces; the amorphous phase content increases with distance into the cast sample. These results underscore the importance of solidification conditions and attendant nanophase selection, on the resultant magnetic properties of this class of alloys.