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

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

Journal of Materials Research ◽

10.1557/jmr.2004.0358 ◽

2004 ◽

Vol 19 (9) ◽

pp. 2730-2737 ◽

Cited By ~ 11

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.

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Characteristic and Sinterability of Alumina-Zirconia-Yttria Nanoparticles Prepared by Different Chemical Methods

Advances in Science and Technology ◽

10.4028/www.scientific.net/ast.87.30 ◽

2014 ◽

Vol 87 ◽

pp. 30-35

Author(s):

Janis Grabis ◽

Dzidra Jankovica ◽

Ints Steins ◽

Krisjanis Smits ◽

Inta Sipola

Keyword(s):

Phase Transition ◽

Spark Plasma Sintering ◽

Molten Salts ◽

Preparation Method ◽

Bulk Materials ◽

Chemical Methods ◽

Plasma Sintering ◽

Spark Plasma ◽

The Impact ◽

Sintering Method

The characteristics and sinterability of the Al2O3-ZrO2(Y2O3) nanoparticles produced by simple and effective microwave and molten salts methods and processed by using spark plasma sintering were studied and compared. The crystalline powders with the specific surface area in the range of 72–108 m2/g and crystallite size of 5–13 nm were obtained by calcination of samples prepared by both methods at 800 °C. The content of t-ZrO2 phase depends on concentration of Al2O3, Y2O3 and on calcination temperature but the impact of the preparation method is insignificant. The phase transition of tetragonal ZrO2 to monoclinic for the samples without Y2O3 started at 1000 °C though it was incomplete in the case of high content of Al2O3. The bulk materials with relative density of 86.1–98.7% were fabricated by the spark plasma sintering method at 1500–1600 °C depending on the content of Al2O3 and Y2O3.

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