Tdk Corporation

Taeko Tsubokura

Eiji Kato

Chikara Ishizaka

Takeshi Masuda

Yoshinori Fujikawa

Katsuo Sato

Masashi Miwa

Tamotsu Ishiyama

Nobuhiro Jingu

Koji Miura

Taku Murase

Toshihiro Kuroshima

Koji Mitake

Takeshi Nomura

Makoto Iwasaki

Hitoshi Oka

Takeo Tsukada

Yoshitomo Tanaka

Fumitaka Baba

Makoto Nakane

Masayoshi Inoue

Kazuo Miyabe

Atsushi Fujiwara

A magnet structure includes a first sintered magnet, a second sintered magnet, and an intermediate layer disposed between the first sintered magnet and the second sintered magnet. Each of the first sintered magnet and the second sintered magnet independently includes crystal grains containing a rare earth element, a transition metal element, and boron. The intermediate layer contains rare earth element oxide phases and crystal grains containing a rare earth element, transition metal element, and boron. Each of the transition metal elements independently includes Fe or a combination of Fe and Co. An average coverage factor of the rare earth element oxide phases measured on the basis of a cross section perpendicular to the intermediate layer of the magnet structure is within a range of 10% to 69%.

Magnet structure

Provided is a permanent magnet including a rare-earth element R (such as Nd), a transition metal element T (such as Fe), B, Zr, and Cu. The permanent magnet contains a plurality of main phase grains including Nd, T, and B, and grain boundary multiple junctions, the one grain boundary multiple junction is a grain boundary surrounded by three or more of the main phase grains, one of the grain boundary multiple junctions contains a ZrBcrystal and an R&#x2014;Cu-rich phase including R and Cu, Fe is contained in the ZrBcrystal, a total concentration of Nd and Pr in the one grain boundary multiple junction containing both the ZrBcrystal and the R&#x2014;Cu-rich phase is higher than a total concentration of Nd and Pr in the main phase grain, a concentration of Cu in the one grain boundary multiple junction containing both the ZrBcrystal and the R&#x2014;Cu-rich phase is higher than a concentration of Cu in the main phase grain, and a unit of the concentration of each of Nd, Pr, and Cu is atomic %.

R-T-B based permanent magnet

Provided is a permanent magnet including a rare-earth element R, a transition metal element T, B, Zr, and Cu. The permanent magnet contains main phase grains including Nd, T, and B, and grain boundary multiple junctions, the grain boundary multiple junction is a grain boundary surrounded by three or more of the main phase grains, one of the grain boundary multiple junctions contains a ZrBcrystal and an R&#x2014;Cu-rich phase, a concentration of B in the grain boundary multiple junction containing both the ZrBcrystal and the R&#x2014;Cu-rich phase is from 5 to 20 atomic %, a concentration of Cu in the grain boundary multiple junction containing both the ZrBcrystal and the R&#x2014;Cu-rich phase is from 5 to 25 atomic %, and a surface layer part of the main phase grain includes at least one kind of heavy rare-earth element among Tb and Dy.

A method for manufacturing an R-T-B permanent magnet comprises a diffusion step of adhering a diffusing material to the surface of a magnet base material and heating the magnet base material with the diffusing material adhered thereto, wherein the magnet base material comprises rare-earth elements R, transition metal elements T and boron B; at least some of R are Nd; at least some of T are Fe; the diffusing material comprises a first component, a second component and a third component; the first component is at least one of a simple substance of Tb and a simple substance of Dy; the second component comprises a metal comprising at least one of Nd and Pr and not comprising Tb and Dy; and the third component is at least one selected from the group consisting of a simple substance of Cu, an alloy comprising Cu, and a compound of Cu.

Method for manufacturing R-T-B permanent magnet

The present invention provides a magnet structure comprising a first magnet, a second magnet, and an intermediate layer joining the first magnet and the second magnet. In the magnet structure, each of the first magnet and the second magnet is a permanent magnet comprising a rare earth element R, a transition metal element T, and boron B. In addition, the rare earth element R comprises: a light rare earth element Rcomprising at least Nd; and a heavy rare earth element R, and the transition metal element T comprises Fe, Co, and Cu. Further, the intermediate layer comprises: an Roxide phase comprising an oxide of the light rare earth element R; and an R&#x2014;Co&#x2014;Cu phase comprising the light rare element R, Co, and Cu.

The present invention provides an R-T-B based permanent magnet having excellent magnetic properties and corrosion resistance even when Co content is small. The R-T-B based permanent magnet in which R is a rare earth element including one or more selected from Nd and Pr and one or more selected from Dy and Tb, T is a combination of Fe and Co, and B is boron. The R-T-B based permanent magnet further includes Zr. A total content of Nd, Pr, Dy, and Tb is 30.00 mass % to 32.20 mass %, Co content is 0.30 mass % to 1.30 mass %, Zr content is 0.21 mass % to 0.85 mass %, and B content is 0.90 mass % to 1.02 mass % with respect to 100 mass % of the R-T-B based permanent magnet.

An R-T-B permanent magnet comprises rare-earth elements R, transition metal elements T, and boron B; wherein at least some of the rare-earth elements R is Nd and at least one of Tb and Dy; at least some of the transition metal elements T are Fe; the R-T-B permanent magnet comprises a plurality of main phase grains and grain boundary triple points each surrounded by the main phase grains; the grain boundary triple points comprise at least one of Nd and Pr, at least one of Tb and Dy, at least one of Fe and Co, and copper; the average contents of Nd, Pr, Tb, Dy, Fe, Co and Cu each (unit: atom %) are represented by [Nd], [Pr], [Tb], [Dy], [Fe], [Co] and [Cu]; ([Fe]+[Co])/([Nd]+[Pr]) is 2 or more and 5 or less; and [Cu]/([Tb]+[Dy]) is 1 or more and 4 or less.

R-T-B permanent magnet

The present invention provides a rare earth based magnet that inhibits the high temperature demagnetization rate even when less or no heavy rare earth elements such as Dy, Tb and the like are used. The rare earth based magnet according to the present invention includes RTB main phase crystal grains and grain boundary phases between adjacent main phase crystal grains. In any cross-section of the rare earth based magnet, when evaluating the circular degree of the main phase crystal grains with Wadell's Roundness A, the shape of the main phase crystal grains is controlled such that the Roundness A becomes 0.24 or more.

Rare earth based magnet

The present invention provides a rare earth based magnet that inhibits the high temperature demagnetization rate even when less or no heavy rare earth elements such as Dy, Tb and the like than before are used. The rare earth based magnet according to the present invention is a sintered magnet which includes RTB crystal grains as main phase and grain boundary phases between the RTB crystal grains. When the grain boundary phase surrounded by three or more main phase crystal grains is regarded as the grain boundary multi-point, the microstructure of the sintered body is controlled so that the ratio of the grain boundary triple-point surrounded by three main phase crystal grains in all grain boundary multi-points to be specified value or less.

The present invention provides a rare earth based magnet including RTB main-phase crystal grains, and two-grain boundary phases between adjacent two RTB main-phase crystal grains, the two-grain boundary phases are controlled such that the thickness thereof is 5 nm or more and 500 nm or less, and it is composed of a phase with a magnetism different from that of a ferromagnet.

The present invention provides a rare earth based magnet that inhibits the high temperature demagnetization rate even when less or no heavy rare earth elements such as Dy, Tb and the like than before are used. The rare earth based magnet according to the present invention is a sintered magnet which includes RTB crystal grains as main phase and grain boundary phases between the RTB crystal grains. when evaluating the cross-sectional area distribution of the main phase crystal grains by histogram in any cross-section of the rare earth based magnet, the crystal grains with large particle size and the crystal grains with small particle size are controlled so that the cross-sectional area distribution becomes the one which respectively has at least one peak at two sides of the average value of the cross-sectional area.

A sintered magnet of a preferred embodiment has a composition comprising: R (R is a rare earth element that must contain any one of Nd and Pr.): 29.5 to 33.0 mass %; B: 0.7 to 0.95 mass %; Al: 0.03 to 0.6 mass %; Cu: 0.01 to 1.5 mass %; Co: 3.0 mass % or less (provided that 0 mass % is not included.); Ga: 0.1 to 1.0 mass %; C: 0.05 to 0.3 mass %; O: 0.03 to 0.4 mass %; and Fe and other elements: a balance, and wherein a content of heavy rare earth elements in total is 1.0 mass % or less, and wherein the following relations are satisfied: 0.29&#x3c;[B]/([Nd]+[Pr])&#x3c;0.40 and 0.07&#x3c;([Ga]+[C])/[B]&#x3c;0.60, where [Nd], [Pr], [B], [C] and [Ga] represent the numbers of atoms of Nd, Pr, B, C and Ga, respectively.

Sintered magnet

An R-T-B based alloy strip including columnar crystals of an RTB phase, wherein in a cross-section along the thickness direction, columnar crystals extend out in a radial fashion from the crystal nuclei, the R-T-B based alloy strip satisfying the following inequality (1), where Dand Dare, respectively, the average value for the lengths of the columnar crystals on one side and the average value for the lengths on the other side that is opposite the one side, in the direction perpendicular to the thickness direction of the cross-section.0.9/1.1&#x2266;&#x2266;1.1/0.9&#x2003;&#x2003;(1)

R-T-B based alloy strip, and R-T-B based sintered magnet and method for producing same

An R-T-B sintered magnet including a composition containing a rare earth element, a transition element and boron, containing essentially no dysprosium as a rare earth element, and having crystal grains with a composition containing a rare earth element, a transition element and boron, and grain boundary regions formed between the crystal grains, wherein the triple point regions which are grain boundary regions surrounded by 3 or more crystal grains have a composition containing a rare earth element, a transition element and boron and have a higher mass ratio of the rare earth element than the crystal grains, the average value of the area of the triple point regions in a cross-section being no greater than 2 &#x3bc;mand the standard deviation of the area distribution being no greater than 3.

R-T-B based sintered magnet and production method for same, and rotary machine

An R-T-B based alloy strip containing dendritic crystals including a RTB phase, wherein on at least one surface, the average value for the widths of the dendritic crystals is no greater than 60 &#x3bc;m, and the number of crystal nuclei in the dendritic crystals is at least 500 per 1 mm square area.

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Tokyo, Japan

Taeko Tsubokura