High remanence (Sm, Zr)Fe7Nx+8 nanocomposite magnets through exchange coupling

We have investigated the influence of α-Fe content on the magnetic properties of (Sm, Zr)Fe7Nx+α-Fe nanocomposite permanent magnet materials. As α-Fe content increases, the saturation magnetization and the remanence increase while the coercivity decreases monotonously. Also we confirmed the influence of microstructure on magnetic properties. Uniform and fine grain sizes of around 20 nm realized high remanence and high squareness of demagnetizing curve such as Br=9.9 kG, HcJ=9.1 kOe, Hk/HcJ=29.9%, and (BH)max=17.8 MGOe. These experimental results agree well with micromagnetic calculations by other researchers. Compaction-molded bonded magnet was prepared by magnetic powders with magnetic properties of Br=9.9 kG, HcJ=8.2 kOe, (BH)max=17.5 MGOe and 2 wt% of epoxy resin. Bonded magnet with a density of 5.91 g/cm3 showed high magnetic properties as follows: Br=7.6 kG, HcJ=8.4 kOe, and (BH)max=12.0 MGOe.