Preparation and magnetic properties of Nd(FeMo) and its nitrides

In this study, a Nd(FeMo) ₁₂ alloy was prepared using a magnetic levitation melting furnace and subsequent heat treatment. The nitrides of this alloy, which exhibit uniaxial anisotropy, were then synthesized by gas-solid reaction. The melting process of the Nd(FeMo) ₁₂ alloy, as well as the microstructure and magnetic properties of the nitrides, was investigated by X-ray diffraction, scanning electron microscopy, transmission electron microscopy, and magnetometer measurements. A homogeneous Nd(FeMo) ₁₂ phase was obtained by magnetic levitation melting using a MoFe alloy as a raw material, followed by heat treatment for 72 h. The nitrogenation of the Nd(FeMo) ₁₂ alloy was investigated. The magnetic properties of Nd(FeMo) _{1 2}N _1.52 powders obtained at a nitriding temperature of 550 °C were enhanced after grinding. No phase decomposition occurred during grinding. The nitriding powders exhibited a fine polycrystalline structure after grinding, as determined by transmission electron microscopy. The coercivity of the powders increased with a decrease in particle size, and Nd(FeMo) ₁₂N _1.52 nano-powders with a coercivity of 3800 Oe was prepared by 70 h of surfactant-assisted high energy ball milling. Nd(FeMo) ₁₂N _1.52 powders obtained exhibit an H _A of 11 T and T _C of 598 K.