Magnetic Properties of Nd-Fe-B-M (M=Si, C) Bulk Nanocomposite Magnets Prepared by the Spark Plasma Sintering Method

2007 ◽  
Vol 1032 ◽  
Author(s):  
Tomokazu Fukuzaki ◽  
Keisuke Tanaka ◽  
Kazue Nishimoto ◽  
Yuji Muro ◽  
Keishi Nishio ◽  
...  
Keyword(s):  
Grain Size ◽  
Magnetic Properties ◽  
Magnetic Phase ◽  
The Other ◽  
Soft Magnetic ◽  
Grain Sizes ◽  
Nanocomposite Magnets ◽  
Plasma Sintering ◽  
Spark Plasma ◽  
Sintering Method

AbstractWe have prepared Nd2Fe14B/Fe3B bulk nanocomposite magnets at the compositions of Nd4Fe77.5B18.5-xMx (M=Si, C) by substitution of other elements M for B. For the sample substituted with 1 at.%Si and sintered at 600 oC, the coercivity exhibits the highest value of 227 kA/m. It has also been found that the grain sizes of the Nd2Fe14B and the Fe3B phases depend on the ramp-up time and the reduction of the grain size leads to an increase of the coercivity. On the other hand, the samples substituted with C exhibit soft magnetic behaviors, which is attributed to the suppression of the precipitation of the Nd2Fe14B hard magnetic phase.

Structures and magnetic properties of Nd–Fe–B bulk nanocomposite magnets produced by the spark plasma sintering method

2004 ◽  
Vol 19 (9) ◽  
pp. 2730-2737 ◽  
Author(s):  
Tetsuji Saito ◽  
Tomonari Takeuchi ◽  
Hiroyuki Kageyama
Keyword(s):  
Magnetic Properties ◽  
Spark Plasma Sintering ◽  
Applied Pressure ◽  
High Coercivity ◽  
Bulk Materials ◽  
Soft Magnetic ◽  
Nanocomposite Magnets ◽  
Plasma Sintering ◽  
Spark Plasma ◽  
Sintering Method

We studied the effects of the sintering temperature and applied pressure on Nd–Fe–B bulk nanocomposite magnets produced by the spark plasma sintering (SPS) method. Amorphous Nd4Fe77.5B18.5 melt-spun ribbons were successfully consolidated into bulk form by the SPS method. When sintered at 873 K under applied pressures between 30 and 70 MPa, the bulk materials consisted of nanocomposite materials with a soft magnetic Fe3B phase and hard magnetic Nd2Fe14B phase. The density and magnetic properties of the bulk materials sintered at 873 K were strongly dependent on the applied pressure during sintering. Bulk Nd4Fe77.5B18.5 nanocomposite magnets sintered at 873 K under an applied pressure of 70 MPa showed a high remanence of 9.3 kG with a high coercivity of 2.5 kOe.

Fabrication of large-size Fe-based glassy cores with good soft magnetic properties by spark plasma sintering

2003 ◽  
Vol 18 (9) ◽  
pp. 2115-2121 ◽  
Author(s):  
Baolong Shen ◽  
Akihisa Inoue
Keyword(s):  
Magnetic Properties ◽  
Supercooled Liquid ◽  
Supercooled Liquid Region ◽  
Liquid Region ◽  
Soft Magnetic Properties ◽  
Soft Magnetic ◽  
Large Size ◽  
High Relative Density ◽  
Plasma Sintering ◽  
Spark Plasma

Glassy Fe65Co10Ga5P12C4B4 alloy powders with a large supercooled liquid region of 50 K before crystallization were synthesized in the particle size range below 125 μm by Ar gas atomization. With the aim of developing a large-size Fe-based glassy core with good soft magnetic properties, the consolidation method of spark plasma sintering was applied to the Fe65Co10Ga5P12C4B4 glassy powders. The existence of the supercooled liquid region enabled us to form a large-size glassy alloy disc 20 mm in diameter and 5 mm in thickness with a high relative density of 99.7% at the glass-transition temperature of 723 K and under the external applied pressure of 300 MPa. The resulting glassy core of 18 mm in outer diameter, 10 mm in inner diameter, and 4 mm in thickness exhibits good soft magnetic properties: 1.20 T for saturation magnetization, 6 A/m for coercive force, and 8900 for maximum permeability. The good soft magnetic properties of the Fe-based bulk glassy core are attributed to the combination of the high relative density and the maintenance of the single glassy structure.

Structures and magnetic properties of Sm-Fe-N bulk magnets produced by the spark plasma sintering method

2007 ◽  
Vol 22 (11) ◽  
pp. 3130-3136 ◽  
Author(s):  
Tetsuji Saito
Keyword(s):  
Magnetic Properties ◽  
Spark Plasma Sintering ◽  
Bulk Material ◽  
Decomposition Temperature ◽  
High Coercivity ◽  
Bulk Materials ◽  
Plasma Sintering ◽  
Spark Plasma ◽  
Sintering Method ◽  
N Powder

Sm-Fe-N powders were successfully consolidated at 873 K and below by the spark plasma sintering (SPS) method. Although the decomposition temperature of the hard magnetic Sm2Fe17N3 phase has been reported to be 873 K, partial decomposition of the Sm2Fe17N3 phase was noted in the bulk materials obtained by sintering at below that temperature. The resultant bulk materials showed a coercivity of around 0.24 MAm−1, significantly lower than that of the original Sm-Fe-N powder. It was found that decomposition of the Sm2Fe17N3 phase in the SPS method was significantly lowered by the addition of a small amount of Zn powder to the Sm-Fe-N powder. The bulk material obtained by sintering a mixture of Sm-Fe-N and Zn powder (10%Zn) at 723 K exhibited high coercivity, comparable with that of the original Sm-Fe-N powder.

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