Tdk Corporation

Ryota Kunieda

Hideki Nakamura

Yoshinori Fujikawa

Takuma Hayakawa

Tetsuya Chiba

Kenichi Nishikawa

Satoshi Tanaka

Makoto Iwasaki

Fumitaka Baba

Makoto Nakane

Atsushi Fujiwara

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

The present invention provides a sintered magnet having superior residual magnetic flux density and coercive force. The sintered magnet of the present invention comprises a group of R-T-B based rare earth magnet crystal particleshaving a coreand a shellcovering the core, the mass ratio of a heavy rare earth element in the shellis higher than the mass ratio of a heavy rare earth element in the core, and the thickest part of the shellin the crystal particlesfaces a grain boundary triple junction. A lattice defectis formed between the coreand the shell

Sintered magnet, motor, automobile, and method for producing sintered 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.

Rare earth based sintered magnet

Growing community of inventors

Tokyo, Japan

Ryota Kunieda