Microstructure of flash and conventionally annealed melt spun NdFeB (abstract)

Abstract

Spring magnets consist of a mixture of exchanged coupled, hard and soft magnetic phases and exhibit improved energy products and remanence. In this study, magnets containing a mixture of Nd2Fe14B and Fe3B have been fabricated using melt spinning under either Ar or He atmospheres. In addition, samples have been heat treated using conventional (furnace) annealing and flash annealing techniques. Magnetic measurements using VSM confirm good spring magnet behavior for all the conventionally annealed samples and for samples flash annealed for t<30 s and T<750 °C. X-ray diffraction reveals that α–Fe, Fe3B, and Nd2Fe14B are present in different amounts depending on the annealing conditions. Transmission electron microscopy shows differences in grain size, crystallinity, and phase distribution. Lorentz electron microscopy reveals the influence of the microstructure on the magnetic domain structure. These results are correlated with the observed magnetic properties.