Influence of Nd Doping on the Magnetic Properties of Nd2Fe14B/α-Fe Nanocomposite Magnets

Soft magnetic alloys Fe95Nd5and Fe89.5Nd10.5were made by the mechanically ball milling to investigate the influence of Nd doping on the magnetic properties of Nd2Fe14B/α-Fe nanocomposite magnets. The coercivity was enhanced with increasing Nd of the pre-alloyed Nd-Fe soft powders. The further discussions on Nd2Fe14B/α-Fe nanocomposite were also carried out through directly mixing the pure Nd as the interface improving agent. Compared with Nd-Fe pre-alloys, the direct addition of Nd was more favorable to reinforce the coercivity of nanocomposite magnets and the squareness of demagnetization curve, thereby increasing the maximum magnetic energy product.

Electroless Fabrication of Nd-Fe-B/α-Fe Heterostructured Composite Magnets and their Magnetic Properties

Electroless plating was used to coat Fe layers on the hard magnetic Nd-Fe-B powders to fabricate Nd-Fe-B/α-Fe heterostructured magnetic powders. The heat treatment was performed to study the property evolution of the heterostructured magnetic powders. The results show that Fe coating was oxidized to Fe2O3while drying; through the hydrogen reduction annealing, Fe2O3was reduced to α-Fe. The coercivity of the heterostructured magnetic powders increased from 111.3 kA/m (1.4 kOe) to 524.7 kA/m (6.6 kOe) after annealing at 650°C. However, the demagnetization curve of powders presents a kink due to un-ideal coupling between hard and soft magnetic phases because of the aggregation of α-Fe. The magnetization processes of the heterostructured powders transferred from the dominant nucleation mechanism to domain wall pinning mechanism after the heat treatment.

Improvement of PM-TFMs Characteristics by Flux Path Guiding

A study for the enhancement of effective magnetic flux of Permanent Magnet-Transversal Flux Machines using flux guiding is presented. By taking into account an intrinsic demagnetization curve which considers the leakage flux, the stator winding can be more compact; furthermore, a lighter stator and a more efficient permanent magnet machine can be obtained by using magnetic flux path guiding.

MAGNETIC INTERACTION OF THE COMPOSITE MIXTURES Nd-Fe-B/Sm2Co17

Hybrid-bonded isotropic Nd-Fe-B /anisotropic Sm 2 Co 17 magnets with different mass fraction of Sm 2 Co 17 powders had been analyzed with the aid of magnetization and demagnetization curves. It was found that the Henkel plot of magnet with 10 wt.% Sm 2 Co 17 lies above the Wohlfarth line at low magnetic field but goes down slowly and then lies below the Wohlfarth line at high magnetic field. This shows magnetizing interaction at first and demagnetizing interaction at last, and presents an s-shaped behavior that has been seen frequently in nanocomposite exchange-coupled magnets. The demagnetization curve of 10 wt.% Sm 2 Co 17 content hybrid-bonded magnet exhibits a magnetically single phase behavior which has also been seen frequently in nanocomposite exchange-coupled magnets, indicating complex magnetic interaction between these two magnetic particles. As a result, a small increase in remanence and energy product are observed in hybrid-bonded Nd-Fe-B/Sm 2 Co 17 magnets with 10% mass fraction of Sm 2 Co 17.