Magnetic and structural properties of rapidly solidified Nd3Pr3Fe67Co3Nb3Ti1B20 nanomagnet

Abstract Present work deduces the development of Nd3Pr3Fe67Co3Nb3Ti1B20 nanomagnets produced through magnetic annealing the amorphous precursors prepared through rapid solidification technique. Changes in structure and magnetic properties were investigated at as-cast and annealed stages. Results revealed that magnetic field annealing stimulates the kinetics of crystallization and modifies the structure and magnetic properties of the Nd3Pr3Fe67Co3Nb3Ti1B20 nanomagnets. Thermal analysis showed a glass transition temperature at 845 K and a crystallization temperature at 890 K for the alloy. X-ray diffraction studies demonstrated that as-cast alloy has amorphous structure while annealed magnet has multi-phase crystalline structure. Phase analysis elucidated that optimal annealed structure is compose of 34% Nd2Fe14B, 32% Pr2Fe14B, 21% α-Fe and 13% Fe3B phases. The HRTEM studies provoked that magnet microstructure consists of 55 nm Nd2Fe14B, 50 nm Pr2Fe14B, 24 nm α-Fe and 20 nm Fe3B magnetic grains which were interacted through ultra-thin grain boundaries. Henkel plot showed that grains of hard magnetic Nd2Fe14B (Pr2Fe14B) phase are coupled to grains of soft magnetic α-Fe (Fe3B) phase. Magnetic properties of nanocomposite magnets depend critically on the mass fraction of alloy constituent elements, casting conditions and heat treatment parameters. A small deviation of ±30 K from the ideal annealing temperature may affect the morphology of phases in the microstructure, which, in turn, influences the resultant magnetic properties of the final magnetic product. Optimal annealed Nd3Pr3Fe65Co3Nb3Ti1B20 rod magnet enunciated coercivity of 630 kA/m, remanence of 0.83 T and magnetic energy product of 84.3 kJ/m3. The present research work opens a new way to manufacture high performance magnetic components for advanced electronic devices, magnetic systems and magnetic recording media.