Synthesis of high-energy-density Pr2Fe14-xCoxB, x<=3, magnets for practical applications

Abstract

Stable magnetic powders, of 1-2 mu m particle size, of partially Go-substituted, Pr2Fe14-xCoxB, x less than or equal to 3, alloys together with 2-4 at% excess Pr were prepared by rapidly quenching the associated melts into thin ribbons and then mechanical attriting the ribbons in the refined particle sizes. The saturation magnetization M(s), remanent magnetization J(r), intrinsic coercivity H-ci and Curie temperature T-c were studied in characterizing the powders for fabricating into sintered or polymer bonded magnets. it is found that the small x = 0.4-0.8 substitution of the Co on Fe sites in this series sensitively leads to an increase in the value of H-ci, by as much as 40%, with the optimum value of 21 kOe at x similar to 0.55, together with an improvement in the T-c from 292 degrees C to 325 degrees C. Without significantly diluting the M(s) similar to 150 emu/g and J(r) similar to 8.0 kG values. The Co-substituted Pr2Fe14B alloy particles are better stable and corrosion resistant in ambient atmosphere. The results are discussed with the microstructure and comparison with the data for Nd2Fe14B powders processed under the same conditions.