Tdk Corporation

Haruna Nakajima

Masashi Miwa

Chikara Ishizaka

Tetsuya Hidaka

Jun Hagiwara

Isao Kanada

Ken-ichi Nishikawa

Eiji Kato

Makoto Iwasaki

Takeshi Masuda

Yoshinori Fujikawa

Takuma Hayakawa

Koji Mitake

Syota Goto

Takurou Iwasa

Ayato Kakoki

An R-T-B based sintered magnet has excellent corrosion resistance together with good magnetic properties. The R-T-B based sintered magnet contains RTB grains, wherein, an R&#x2014;Cu-M-C concentrated part is existed in a grain boundary formed between or among two or more adjacent RTB grains, and the concentrations of R (R is at least one from Sc, Y and the lanthanoide element), Cu, M (M is at least one from Ga, Si, Sn, Ge and Bi) and C in the R&#x2014;Cu-M-C concentrated part are higher than those in the RTB grains respectively.

R-T-B based sintered magnet and motor

The present invention provides an R-T-B based sintered magnet having an R-T-B based compound as main phase grains, wherein, the content of Zr contained in the R-T-B based sintered magnet is 0.3 mass % to 2.0 mass %, the main phase grains have Zr, and the R-T-B based sintered magnet have main phase grains with the mass concentration of Zr at the edge portion of the main phase grain being 70% or less of that at the central portion of the main phase grain at the cross-section of the main phase grain.

R-T-B based sintered magnet

The present invention provides an R-T-B based sintered magnet having excellent corrosion resistance together with good magnetic properties. The R-T-B based sintered magnet contains RTB crystal grains, wherein, an R&#x2014;Ga&#x2014;Co&#x2014;Cu&#x2014;N concentrated part exists in a grain boundary formed between or among two or more adjacent RTB crystal grains, and the concentrations of R, Ga, Co, Cu and N in the R&#x2014;Ga&#x2014;Co&#x2014;Cu&#x2014;N concentrated part are higher than those in the RTB crystal grains respectively.

R-T-B BASED SINTERED MAGNET AND ROTATING MACHINE

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 having RTB crystal grains and a grain boundary formed by two or more adjacent RTB crystal grains. An R&#x2014;Co&#x2014;Cu&#x2014;N concentrated part whose concentrations of R, Co, Cu and N are respectively higher than those in the RTB crystal grains may be in the grain boundary. An R&#x2014;O&#x2014;C concentrated part or an R&#x2014;O&#x2014;C&#x2014;N concentrated part may be further provided in the grain boundary.

The present invention provides an R-T-B based sintered magnet including RTB crystal grains wherein; a grain boundary is formed by two or more adjacent RTB crystal grains, an R&#x2014;O&#x2014;C concentrated part, in which concentrations of R, O and C are higher than those in the RTB crystal grains respectively, is in the grain boundary, and a ratio (O/R) of O atom to R atom in the R&#x2014;O&#x2014;C concentrated part satisfies the following formula (1):0.4&#x3c;(O/R)&#x3c;0.7.

The present invention provides an R-T-B based sintered magnet including RTB crystal grains wherein; a grain boundary is formed by two or more adjacent RTB crystal grains, an R&#x2014;O&#x2014;C concentrated part, in which concentrations of R, O and C are higher than those in the RTB crystal grains respectively, is in the grain boundary, and an area of the R&#x2014;O&#x2014;C concentrated part occupying in that of the grain boundary on a cut surface of the R-T-B based sintered magnet is within a range of 10% or more to 75% or less.

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Tokyo, Japan

Haruna Nakajima