Abstract
•Pr4Fe67Nb4Cu2Zr1B22 nanocomposite permanent magnets in rod shape are produced.•Improvements in properties are obtained with Pr4Fe67Nb4Cu2Zr1B22 alloy.•Ideal elemental proportions and exchange coupled grains led to enhance properties.•Magnet yielded properties as Hc of 382 kA/m, Br of 0.7 T, (BH)max of 62.4 kJ/m3.
Present research work narrates synthesis, structural, thermal and magnetic characteristics of Pr4Fe67Nb4Cu2Zr1B22 nanocomposite magnets. Amorphous Pr4Fe67Nb4Cu2Zr1B22 rods were produced through injection casting technique and permanent magnetic characteristics were obtained by one-step annealing the amorphous rods. XRD analysis elucidated that as-cast rods have amorphous phase structure and annealed magnets have tetragonal Pr2Fe14B hard phase, cubic structural α-Fe phase and tetragonal Fe3B soft phase. Optimal annealed magnet composed of 63% Pr2Fe14B hard phase, 26% α-Fe and 11% Fe3B soft phases with mean grain sizes around 51.6 ± 1 nm for Pr2Fe14B, 25.4 ± 2 nm for α-Fe and 21.5 ± 2 nm for Fe3B phases. Microscopic and atomic probe studies showed that the annealed magnet consists of Pr2Fe14B, α-Fe, Fe3B nanosized grains interlinked with thin grain boundaries. Henkel curve evidenced the existence of inter-grain exchange coupling between magnetic nanophase grains. Magnetic hysteresis measurements revealed that Pr4Fe67Nb4Cu2Zr1B22 nanocomposite magnet yielded maximum magnetic characteristics such as coercivity Hc of 382 kA/m, remanence Br of 0.70 T and maximum energy product (BH)max of 64.2 kJ/m3 with rare earth to iron ratio 4:67.