Tdk Corporation

Kenichi Nishikawa

Takeshi Takahashi

Ryuji Hashimoto

Takuma Hayakawa

Tetsuya Chiba

Ryota Kunieda

Kenichi Suzuki

Yoshinori Fujikawa

Yasushi Enokido

Kyung-Ku Choi

Seigo Tokoro

Tomoshi Nakamoto

Seiichi Kikuchi

The present invention provides an R-T-B based permanent magnet suitable as a magnet with a variable magnetic force for a motor with variable magnetic flux, which has a high residual magnetic flux density, a low coercivity, and a magnetic force that can be reversibly varied by a small external magnetic field. A permanent magnet with a high residual magnetic flux density and a low coercivity that is suitable as a variable magnet for a motor with variable magnetic flux can be obtained, by selecting the rare earth elements consisting of one or more of Y, La and Ce for a predetermined amount of the rare earth element(s) R in the R-T-B based permanent magnet, and further adding a predetermined amount of the additive element(s) which is at least one of Al, Cu, Zr, Hf and Ti.

R-T-B based permanent magnet and rotating machine

The present invention provides a soft magnetic powder core with a high electrical resistivity and a high strength. The soft magnetic powder core of the present invention is characterized in that in the soft magnetic powder core containing soft magnetic metal particles with Fe as the main component, the powder core has the structure in which oxide portions are present among soft magnetic metal particles, and the oxide portions are composed of oxides containing V, B and Fe. Further, the amount of B contained in the oxide portions of the powder core is 0.5 or more times and 5.0 or less times of the amount of V in terms of mass ratio.

Soft magnetic powder core

An R-T-B based sintered magnet maintains high magnetic properties and decreases usage of heavy rare earth elements. The magnet includes main phase grains and grain boundary phases, the main phase grain containing a core portion and a shell portion. X in the main phase LR(2-x)HRxT14B of the core portion ranges from 0.00 to 0.07; x in the main phase LR(2-x)HRxT14B of the shell portion ranges from 0.02 to 0.40; and the maximum thickness of the shell portion ranges from 7 nm to 100 nm. LR contains Nd and one or more light rare earth elements consisting of Y, La, Ce, Pr and Sm; HR contains Dy or/and Tb and one or more heavy rare earth elements consisting of Gd, Ho, Er, Tm, Yb and Lu; T contains Fe or/and Co and one or two kinds of Mn and Ni; and B represents boron partly replaced by C (carbon).

R-T-B based sintered magnet

A soft magnetic powder core which can have a high electrical resistivity, a high magnetic flux density and a high strength easily, and the soft magnetic powder core can be used in various electromagnetic components such as a motor, an actuator, a generator and a reactor. The soft magnetic powder core in which the glass portion is scattered among the soft magnetic particles, the soft magnetic particle having the core particle with iron as the main component and the insulating coating layer containing P, O and Fe. Further, the junction portion with iron oxide as the main component is formed between the soft magnetic particle and the glass portion.

The present invention provides a permanent magnet which is excellent in the temperature properties and the magnetic properties of which will not be significantly decreased, compared to the conventional R-T-B based permanent magnet. In the R-T-B based structure, a stacked structure of R1-T-B based crystal layer and Y-T-B based crystal layer can be formed by alternatively stacking R1-T-B and Y-T-B. In this way, a high magnetic anisotropy field of the R1-T-B based crystal layer can be maintained while the temperature coefficient of the Y-T-B based crystal layer can be improved.

R-T-B based permanent magnet

The present invention provides a rare earth based sintered magnet. The magnet is a rare earth based permanent magnet with a R-T-B (R represents one or more elements selected from Y and rare earth elements, T represents one or more metal elements including Fe or the combination of Fe and Co, and B represents B or the combination of B and C) based composition. When a R-rich phase (R represents rare earth element(s)) with atomic ratio of (Fe+Co)/(LR+HR+Fe+Co)&#x2266;0.2 (LR represents Y and light rare earth element(s) selected fromLa toEu, and HR represents heavy rare earth element(s) selected fromGd toLu) is present in the grain boundary triple point, a region with HR/(LR+HR)&#x2267;0.01 (atomic ratio) is present in the R-rich phase, and the region with HR/(LR+HR)&#x2267;0.01 accounts for 10% to 90% of the area of the grain boundary triple point.

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Tokyo, Japan

Kenichi Nishikawa