Tdk Corporation

Takuma Hayakawa

Makoto Iwasaki

Tetsuya Hidaka

Ayato Kakoki

Eiji Kato

Hidetake Kitaoka

Yoshinori Fujikawa

Tetsuya Chiba

Kenichi Nishikawa

Ryota Kunieda

Takeshi Masuda

Chikara Ishizaka

Syota Goto

Fumitaka Baba

Naoto Tsukamoto

Haruna Nakajima

Atsushi Fujiwara

Ryouta Kunieda

A rare earth permanent magnet has a first surface and satisfies A1<B1, A1≥C1, and A1≥D1 where A1 is a coercive force of a portion aincluding a center of gravity of the first surface, B1 is a coercive force of a portion b, C1 is a coercive force of a portion c, and D1 is a coercive force of a portion d, and a heavy rare earth element is present on a top layer of the first surface.

Rare earth permanent magnet and rotating electric machine including the same

An R-T-B based sintered magnet containing a first heavy rare earth element, in which R includes Nd, T includes Co and Fe, the first heavy rare earth element includes Tb or Dy, the R-T-B based sintered magnet has a region in which a concentration of the first heavy rare earth element decreases from the surface toward the inside, a first grain boundary phase which contains the first heavy rare earth element and Nd but does not contain Co is present in one cross section including the region, and an area occupied by the first grain boundary phase in one cross section including the region is 1.8% or less.

R-T-B based sintered magnet

Provided is an alloy for R-T-B based rare earth magnet. 'R' is one or more of a rare earth element, 'T' is one or more of a transition metal element essentially including Fe or Fe and Co, and 'B' is boron. The alloy includes a single or a plural number of main phase (A), having a minimum length of 10 &#x3bc;m or more and a maximum length of 30 &#x3bc;m or more and 300 &#x3bc;m or less, in a cross section cut along a thickness direction of the alloy. The main phase (A) includes an RTB phase, and an area ratio of the main phase (A) to an entire cross section is 2% or more and 60% or less.

Alloy for R&#x2014;T&#x2014;B based rare earth sintered magnet and method for producing the R&#x2014;T&#x2014;B based rare earth sintered magnet

Provided is a motor including a permanent magnet, in which the permanent magnet includes a high temperature side permanent magnet part exposed to a high temperature inside the motor, and a low temperature side permanent magnet part exposed to a temperature lower than the high temperature inside the motor, and a coercive force of the high temperature side permanent magnet part is higher than the coercive force of the low temperature side permanent magnet part.

Motor containing a permanent magnet having high and low temperature side permanent magnet parts

Provided is an R-T-B based rare earth magnet. R is one or more rare earth elements, T is one or more transition metal elements essentially including Fe or Fe and Co, and B is boron. B content with respect to a total R-T-B based rare earth magnet is 0.80 mass % or more and 0.98 mass % or less. The R-T-B based rare earth magnet includes an RTBphase.

R-T-B based rare earth magnet

An R-T-B based sintered magnet includes 'R', 'T', and &#x201c;B&#x201d;. &#x201c;R&#x201d; represents a rare earth element. &#x201c;T&#x201d; represents a metal element other than rare earth elements including at least Fe, Cu, Mn, Al, Co, Ga, and Zr. &#x201c;B&#x201d; represents boron or boron and carbon. With respect to 100 mass % of a total mass of the R-T-B based sintered magnet, a content of &#x201c;R&#x201d; is 28.0 to 31.5 mass %, a content of Cu is 0.04 to 0.50 mass %, a content of Mn is 0.02 to 0.10 mass %, a content of Al is 0.15 to 0.30 mass %, a content of Co is 0.50 to 3.0 mass %, a content of Ga is 0.08 to 0.30 mass %, a content of Zr is 0.10 to 0.25 mass %, and a content of &#x201c;B&#x201d; is 0.85 to 1.0 mass %.

An R-T-B based sintered magnet includes 'R', 'T', and &#x201c;B&#x201d;. &#x201c;R&#x201d; represents a rare earth element including at least Tb. &#x201c;T&#x201d; represents a metal element except rare earth elements including at least Fe, Cu, Mn, Al, and Co. &#x201c;B&#x201d; represents boron or boron and carbon. With respect to 100 mass % of a total mass of the R-T-B based sintered magnet, a content of &#x201c;R&#x201d; is 28.0 to 32.0 mass %, a content of Cu is 0.04 to 0.50 mass %, a content of Mn is 0.02 to 0.10 mass %, a content of Al is 0.15 to 0.30 mass %, a content of Co is 0.50 to 3.0 mass %, and a content of &#x201c;B&#x201d; is 0.85 to 1.0 mass %. Tb2/Tb1 is 0.40 to less than 1.0, where Tb1 and Tb2 (mass %) denote a content of Tb at a surface portion and at a core portion, respectively.

Provided is a sintered magnet that is an R-T-B based sintered magnet having a region having a concentration of at least one heavy rare earth element decreasing from the surface toward the inside, in which the at least one heavy rare earth element includes at least either of Tb or Dy, R includes Nd, T includes Fe, Co, and Cu, there is a grain boundary phase containing at least either of Tb or Dy and Nd between two main phase particles, and a value obtained by subtracting a half value width of a concentration distribution curve of Cu from a half value width of a concentration distribution curve of Tb or Dy in a part including the grain boundary phase is from 10 to 20 nm.

Alloy for R-T-B based sintered magnet and R-T-B based sintered magnet

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).

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

A rare earth sintered magnet includes a main phase that includes an RTB phase of crystal grain where R is one or more rare earth elements including Nd, T is one or more transition metal elements including Fe or Fe and Co, and B is B or B and C; a grain boundary phase in which a content of R is larger than a content of the RTB phase; and a grain boundary triple point that is surrounded by three or more main phases. The grain boundary triple point includes an R75 phase containing R of 60 at % to 90 at %, Co, and Cu. The relational expression 0.05&#x2266;(Co+Cu)/R&#x3c;0.5 is satisfied. An area where a Co-rich region overlaps with a Cu-rich region in a cross-sectional area of the grain boundary triple point is 60% or more.

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Tokyo, Japan

Takuma Hayakawa