Effect of Pr Substitution on the Magnetic Properties of Nd-Fe-Co-Cu-Nb-B System Exchange Spring Magnets

Abstract

Amorphous melt-spun ribbons of Nd-Pr-Fe-Co-Cu-Nb-B system alloys were prepared by the single-roller rapid-quenching method The effects of composition, wheel velocity, and heat treatment on their magnetic properties were investigated. Amorphous Nd_2.7Pr_6.3Fe_75.5Co₈Cu_0.5Nb₁B₆ ribbons prepared at a wheel velocity of 12.5 m/s were crystallized by heat treatment, and the optimum heat-treatment condition was found to be 675 °C for 0 min,then the value of (BH)_max was 156.16 kJ/m³. The temperature coefficients of J_r and H_cJ for the ribbons crystallized from the amorphous Nd_2.7Pr_6.3Fe_75.5Co₈Cu_0.5Nb₁B₆ alloy are α (J_r) = −0.036 % /°C (reversible) and α (H_cJ) = −0.46 %/°C (irreversible), respectively.