Study Of Preparation And Magnetic Properties Of Rapid Quenched NdFeB Ribbons

Nanocomposite permanent magnets have the advantages of hard magnetic phase's high magnetocrystalline anisotropy and soft magnetic phase's high saturation magnetization, and obtain the excellent magnetic properties by exchange-coupled interaction. Nanocomposite permanent magnets are believed to be promising new candidates for applications in inexpensive bonded permanent magnets, because of their high magnetic energy product of 1090kJ/m³ together with low rare earth concentration and high chemical stability.In the present study, melt-spun and annealing amorphous ribbons have prepared Nd₂Fe₁₄B/α-Fe nanocomposite magnets. The phase component, microstructure and magnetic properties of the ribbons with different composition melt-spun with different wheel speeds and annealed at different temperature was studied by methods of XRD, TEM and VSM.Rapidly quenching speed can influence the crystallizing and magnetic properties of nanocomposite magnets. The hysteresis loops of the alloy at optimal speed reveal typical single-phase characteristic. If quenched speed is too low or high, the hysteresis loops of the alloy reveal two-phase characteristic. And for a relatively low quenched speed, it was found that the c-axis texture existed in the free-side surface. As Nd₂Fe₁₄B/α-Fe nanocomposite magnets are prepared by crystallizing the amorphous ribbons, the optimum magnetic property can be obtained after annealing at 710℃.The additions of DyCoGa in Nd-Fe-B increase the remanence, intrinsic coercivity and maximum energy product. Comparison of Nd-Fe-B, the remanence, intrinsic coercivity and maximum energy product of Nd-Dy-Fe-Co-B-Ga were increased by 18.2%, 34.0% and 9.4% respectively. Comparison of magnetic properties of ribbons with different composition melt-spun with different wheel speeds and annealed at different temperature. The optimum magnetic properties of Nd-Dy-Fe-Co-B-Ga can be obtained at 30m/s,μ₀M_r=0.564T(5.64kGs), H_ci=783.75kA/m(6.24kOe), (BH)_max=94.22 kJ/m³ (11.84 MGOe), M_r/M_s=0.7595.