Magnetics Hysteresis Properties and Microstructure of High-Energy (Nd,Dy)–Fe–B Magnets with Low Oxygen Content

Abstract Magnetic properties and microstructure of high-energy (Nd,Dy)–Fe–B magnets with Dy no more than 1 wt % prepared via a low-oxygen routine are studied. Oxygen content in does not exceed 0.20 %. 0.5 %–Dy addition reliably stabilizes the coercivity M H c higher 13 kOe; this case, maximum energy density product ( BH ) max is 48.5–49.5 MG Oe. High magnetic hysteresis gained optimization chemical phase compositions magnets, as well their microstructure. The grain size main Nd 2 Fe 14 B approximately 3.5 ?m; according to X-ray analysis, weight fraction additional Nd-rich phases (NdO x O 3 2.5%. Scanning electron microscopy study has demonstrated that triple junctions grains there two types inclusions (? ?) NdO phase, which significantly differ by composition. ?-phase low oxygen ? ? 0.03) enriched (40–50 %); whereas, ?-phase high 0.70) contains 3–5 times less Fe. angular dependences presented.