Tetsuhito Yoneyama

Magnetic properties of rapidly quenched high remanence Zr added Sm–Fe–N isotropic powders

The magnetic properties and microstructures of rapidly quenched Sm–Fe–N powders with low Sm contents and Zr and Co addition have been studied. High remanence values of 9.4 kG with high HcJ values of 7–10 kOe were obtained for isotropic powders. The x‐ray diffraction analysis and transmission electron microscopy (TEM) observation showed these alloy powders to consist of a nanoscale mixture with a SmFe7Nx phase with the TbCu7‐type structure and α‐Fe in the size range of 20–30 nm. It is presumed that the high remanence is due to the small crystal size and exchange coupling at interphase boundaries.

Large particle size Sm2Fe17Nx compounds by hydrogen treatment

Large particle size Sm2Fe17Nx with a low oxygen content has been produced by treating Sm2Fe17 with hydrogen before nitrogenation. Large Sm2Fe17Nx particles of more than 2 mm include nearly 3.0‐wt. % nitrogen and a magnetization level of 140 emu/g. The hydrogen decrepitation behavior was not observed for this alloy and the size of samples were not changed after hydrogen treatment and nitrogenation. It is thought that hydrogen absorption and desorption increase the gas‐solid reaction area significantly. The oxygen content of these particles is less than 200 ppm because the fine pulverization step was skipped. The relation between the nitrogen content and magnetization of Sm2Fe17Nx will be presented.

Maqnetic Properties And Phase Transfer Of SmFe/sub 2/And SmFe/sub 3/ Intermetallic comp ounds By Nitrogenation.

Magnetic properties and phase transfer of SmFe/sub 2/ and SmFe/sub 3/ compounds before and after nitrogenation are examined. It is found that SmFe/sub 2/ and SmFe/sub 3/ specimens show ferromagnetic properties with saturation magnetization of around 60 and 80 emu/g and Curie temperature of 425 degrees C and 410 degrees C, respectively. After nitrogenation, these compounds are thought to be decomposed into SmN and alpha Fe, considering X-ray diffraction and thermomagnetic analysis. It is assumed that the produced soft magnetic phase would deteriorate the magnetic properties of Sm rich Sm/sub 2/Fe/sub 17/N/sub x/ type magnets. >

Magnetic Properties of Rapidly Quenched Nd10Fe85-xTxB5 (T=Zr, Nb) Alloys

Magnetic properties were studied for Nd10Fe85-xTxB5(T=Zr, Nb; x=0, 4) alloys, which were first rapidly quenched and then crystallized by heat treatment. An energy product of (BH)max=12.2 MGOe, coercive force of iHc=9.2 kOe, and remanence of Br=8.2 kG were achieved in a Nd10Fe81Zr4B5 alloy; the Nd content is the lowest ever reported for a Nd–Fe–B alloy having a high-energy product.

High performance RFeCoZrB bonded magnets having low Nd content

The magnetic properties of resin bonded magnets made of rapidly quenched RFeCoZrB alloys with lower than stoichiometric Nd content were investigated. Two kinds of alloys were studied: NdFeCoZrB alloys and MM (misch metal)-based RFeCoZrB alloys. Isotropic resin bonded magnets with (BH)/sub max/ as high as 13 MGOe were obtained with the NdFeCoZrB alloys. For the MM-based magnets, a (BH)/sub m/ of 9.5 MGOe was obtained. Both magnets show good magnetizability and high loop squareness. >