Abstract
High coercivity (Nd8Y3)-(Fe62Nb3Cr1)-B-23 magnets in rods have been produced by copper mold injection casting. Magnetic properties, microstructure, and phase evolution in the as-cast and annealed states have been presented and discussed. The (Nd8Y3)-(Fe62Nb3Cr1)-B-23 alloys show hard magnetic properties in the as-cast state. Annealing induces ideal microstructure containing magnetically hard and soft phases with hard/soft volume ratio of 73/27. Exchange coupling between magnetically hard (Nd,Y)(2)Fe14B phase and soft alpha-Fe (Fe3B) phase leads to excellent hard magnetic properties. Highest coercivity of 1230 kA/m in (Nd8Y3)-(Fe62Nb3Cr1)-B-23 magnet originates from the large amount of hard phase with high magnetocrystalline anisotropy, formation of thin grain boundary phase and refinement of magnetic grains. Nb and Cr doping modify the magnetic phases. Annealed magnetic rods with a diameter of 2 mm and 36 mm in length demonstrated the maximum magnetic properties i.e., H-i(c) of 1230 kA/m, B-r of 0.49 T, and (BH)(max) of 45.6 kJ/m(3)