Magnetic Properties of Pr-Fe-Co-V-W-Si-B System Exchange Spring Magnets

Abstract

The melt-spun ribbons of Pr-Fe-Co-V-W-Si-B system alloys were prepared by single roller rapid-quenching method. The effects of composition, surface velocity and heat-treatment on the magnetic properties were investigated. The Pr₉Fe₇₁Co₈V_0.5W_0.5Si_0.5B_10.5 alloy ribbons prepared at a surface velocity of 12.5 m/s were crystallized by heat-treatment, and the optimum heat-treatment condition was found to be at 575 °C for 3 min, then the magnetic properties were (BH)_max = 136.1 kJ/m^3,, J_r = 0.93 T, H_cJ = 652.2 kA/m, and H_cB = 528.3 kA/m. The temperature coefficients of J_r and H_cJ for the ribbons crystallized from melt-spun ribbons of Pr₉Fe₇₁Co₈V_0.5W_0.5Si_0.5B_10.5 alloy were α(J_r)_ave = -0.057 %/°C and α(H_cJ) = -0.450 %/°C. The value of (BH)_max for the compression molding Pr₉Fe₇₁Co₈V_0.5W_0.5Si_0.5B_10.5 isotropic bonded magnet prepared by using the ribbons annealed at 575 °C for 3 min is 80.0 kJ/m³, and the density is 6.24 Mg/m³.