Minxiang Pan

Effects of Ga addition on structural and magnetic properties of nanocomposite Nd-Fe-B-Ti-C thick ribbons

Rapidly solidified Nd9Fe73B12.6C1.4Ti4-xGax (x = 0, 0.5, 1) thick ribbons were prepared by melt spinning technique at a surface speed (vs) of 5 m/s. The influences of Gallium doping on the glass-forming ability (GFA), microstructure and magnetic properties of alloys were investigated. The coercivity of Nd-Fe-B-Ti-C nanocomposite alloy thick ribbons can be dramatically enhanced by 0.5 at. % Ga addition in a low cooling-rate regime, attributing to the weakened exchange coupling interaction and grain refinement. The results of XRD showed that the GFA of Nd-Fe-B-Ti-C alloy was enhanced by the Ga addition. Therefore, Gallium addition is effective to refine grain and improve the glass-forming ability, which provides the possibility to obtain the high performance of magnetic properties by using strip casting (SC) method.

Preparation, Structure, and Magnetic Properties of Nd–Y–Fe–Mo–B Nanocomposite Ribbon and Bulk Magnets

Nanocomposite alloys with the nominal compositions NdxY6-xFe68Mo4B22 (x=1–5) were prepared directly by devitrification of amorphous rods and ribbons. The effect of Y doping on the glass-forming ability (GFA) of the alloys has been investigated. It was found that the GFA of the alloys was enhanced by the substitution of Y for Nd and increased with increasing Y content. The best glass former was Nd1Y5Fe68Mo4B22 with a critical diameter of 4 mm. A comparison of microstructures and magnetic properties between ribbon and bulk magnet with the same composition after optimally annealing treatment was presented in detail. Compared to the Nd3Y3Fe68Mo4B22 ribbons, the better hard magnetic properties have been obtained in the Nd3Y3Fe68Mo4B22 nanocomposite bulk magnet, which can be attributed to much higher relative content of hard magnetic Nd(Y)2Fe14B phase in the crystallized rod sample.

Effect of Zr Addition on the Magnetization Reversal Behavior for α-Fe/Pr2Fe14B Nanocomposite Alloys

The microstructure and magnetic properties of the Zr-doped α-Fe/Pr2Fe14B nanocomposite magnets prepared by melt-spinning method have been studied by X-ray diffraction (XRD), vibrating sample magnetometer (VSM) and superconducting quantum interference device (SQUID) measurements. The magnetization reversal behavior during the recoil processes of nanocomposite alloys has been investigated by analyzing the hysteresis curves and recoil loops of demagnetization curves. An enhanced magnetic properties has been obtained by the addition of 1 at. % Zr in α-Fe/Pr2Fe14B alloys, where the coercivity Hc increases from 470.7 to 793.2 kA/m, the maximum energy product (BH)max from 66.8 to 90.8 kJ/m3, the remanence ratio Mr/Ms from 0.74 to 0.77. The recoil loop results show that the maximum value of the integrated recoil loop area for 1 at. % Zr doped sample is quietly low of 1.87×10-3, only 1/2 for the Zr-free and 1/3 for 5 at. % Zr doped samples respectively. This result indicates that the 1 at. % Zr doped sample has a lower energy loss, resulting from a low recoverable portion of the magnetization remaining as long as the applied reversal field is below the coercivity Hc. This study provides a promising guideline for the future fabrication of low-energy-loss nanocomposite magnets for electric machines and generators.

The microstructure and magnetic properties of (SmLu)(Co, Fe, Cu, Zr)Z magnets with varying Lu content

The 2:17-type SmCo permanent magnet with nominal compositions of Sm1–xLux(CobalFe0.125Cu0.08Zr0.06)7.4 (x = 0, 0.05, 0.1, 0.15) were prepared by a traditional powder metallurgy method. The influence of HRE Lu content on the microstructure and magnetic properties of these magnets were investigated systematically. HRE Lu addition has proved to result in relevant improvements in the microstructure and magnetic properties, especially in the coercivity Hcj. It is shown that a higher coercivity and maximum energy product of about 35.92 kOe and 28.52 MGOe were obtained in the sample with x = 0.15. Meanwhile, the lattice constants have been discussed by indexing the selected area electron diffraction and HRTEM images.

Enhanced magnetic properties in lean rare earth Pr2Fe14B/Fe3B nanocomposite alloys

Abstract The Pr lean Pr2Fe14B/Fe3B nanocomposite alloys were prepared by melt spinning method and subsequent thermal annealing. The effect of annealing temperature on the magnetic properties and the microstructure of these magnets has been investigated. The results show that the optimal magnetic property of Pr2Fe14B/Fe3B nanocomposite alloy with a high coercivity Hc = 211·4 kA m−1, a large remanence Mr = 1·18 T and a large energy product (BH)max = 73·9 kJ m−3 has been obtained by controlling the annealing temperature in the amorphous alloy. The enhanced (BH)max is mainly attributed to the increase in the intergrain exchange coupling effect due to the refined nanocrystal microstructure. This demonstrates that the control of the nanocrystal microstructure in the amorphous alloys plays a significant role for the further improvement of the magnetic properties of these magnets.