Abstract: The present invention provides a rare earth based magnet having a microstructure in which in a section of the R2T14B main-phase crystal grains, the number density of the fine products in the interior of (inside) the crystal grains is larger than that in the periphery of (outside) the crystal grains. That is, the rare earth based magnet includes R2T14B main-phase crystal grains and grain boundary phases formed between the R2T14B main-phase crystal grains. The R2T14B main-phase crystal grains include a substance where fine products are formed in the crystal grains. In the section of the main-phase crystal grains, when the crystal grains are divided into the interior of the crystal grains and the periphery of the crystal grains with a specific ellipse, the fine products are formed such that the number density in the interior is larger than that in the periphery.

Abstract: The present invention provides an R-T-B based sintered magnet including R2T14B crystal grains wherein; a grain boundary is formed by two or more adjacent R2T14B crystal grains, an R—O—C concentrated part, in which concentrations of R, O and C are higher than those in the R2T14B crystal grains respectively, is in the grain boundary, and an area of the R—O—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.

Abstract: Provided is a rare earth sintered magnet 10 comprising a group of main phase grains 2 each composed of an R-T-B-based rare earth magnet comprising a core 4 and a shell 6 covering the core 4, wherein a thickness of the shell 6 is 500 nm or less, R includes a light rare earth element and a heavy rare earth element, and a Zr compound 8 is present in a grain boundary phase 7 of the group of main phase grains 2 and/or the shell 6. Also provided are a motor comprising the rare earth sintered magnet 10 and an automobile comprising the motor.

Abstract: An R-T-B based sintered magnet having R2T14B crystal grains and a grain boundary formed by two or more adjacent R2T14B crystal grains. An R—Co—Cu—N concentrated part whose concentrations of R, Co, Cu and N are respectively higher than those in the R2T14B crystal grains may be in the grain boundary. An R—O—C concentrated part or an R—O—C—N concentrated part may be further provided in the grain boundary.

Abstract: 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 R2T14B crystal grains as main phase and grain boundary phases between the R2T14B 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.

Abstract: 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 R2T14B crystal grains as main phase and grain boundary phases between the R2T14B 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.

Abstract: The present invention provides an R-T-B based sintered magnet including R2T14B crystal grains wherein; a grain boundary is formed by two or more adjacent R2T14B crystal grains, an R—O—C concentrated part, in which concentrations of R, O and C are higher than those in the R2T14B crystal grains respectively, is in the grain boundary, and a ratio (O/R) of O atom to R atom in the R—O—C concentrated part satisfies the following formula (1): 0.4<(O/R)<0.7.

Abstract: The present invention provides a rare earth based magnet in which the demagnetization rate at a high temperature can be inhibited even if the amount of heavy rare earth element(s) such as Dy and Tb is evidently decreased compared to the past or no such heavy rare earth element is used. The rare earth based magnet of the present invention is a sintered magnet which comprises R2T14B crystal grains as the main phases and the crystal boundary phases among R2T14B crystal grains. The microstructure of the sintered body is controlled by at least containing the first crystal boundary phases and the second crystal boundary phases, wherein the first crystal boundary phases contain at least R-T-M in the ranges of 20 to 40 atomic % for R, 60 to 75 atomic % for T and 1 to 10 atomic % for M, and the second crystal boundary phases contains at least R-T-M in the ranges of 50 to 70 atomic % for R, 10 to 30 atomic % for T and 1 to 20 atomic % for M.

Abstract: The present invention provides a rare earth based magnet in which the demagnetization rate at a high temperature can be inhibited even if the amount of heavy rare earth element(s) such as Dy and Tb is evidently decreased compared to the past or no such heavy rare earth element is used. The rare earth based magnet of the present invention is a sintered magnet which comprises R2T14B crystal grains as the main phases and the crystal boundary phases among the R2T14B crystal grains. The microstructure of the sintered body is controlled by including crystal boundary phases containing at least R, T and M in the crystal boundary phases, wherein the relative atomic ratios of R, T and M are as follows, i.e., 25 to 35% for R, 60 to 70% for T and 2 to 10% for M.

Abstract: The present invention provides a rare earth based magnet in which the demagnetization rate at a high temperature can be inhibited even if the amount of heavy rare earth element(s) such as Dy and Tb is evidently decreased compared to the past or no such heavy rare earth element is used. The rare earth based magnet of the present invention is a sintered magnet which comprises R2T14B crystal grains as the major phases and the crystal boundary phases among the R2T14B crystal grains. The microstructure of the sintered body is controlled by including crystal boundary phases containing at least R, T and M in the crystal boundary phases, wherein the relative atomic ratios of R, T and M are as follows, i.e., 60 to 80% for R, 15 to 35% for T and 1 to 20% for M.

Abstract: 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<[B]/([Nd]+[Pr])<0.40 and 0.07<([Ga]+[C])/[B]<0.60, where [Nd], [Pr], [B], [C] and [Ga] represent the numbers of atoms of Nd, Pr, B, C and Ga, respectively.

Abstract: The present invention provides an R-T-B based sintered magnet including R2T14B crystal grains wherein; a grain boundary is formed by two or more adjacent R2T14B crystal grains, an R—O—C concentrated part, in which concentrations of R, O and C are higher than those in the R2T14B crystal grains respectively, is in the grain boundary, and an area of the R—O—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.

Abstract: A rare earth sintered magnet 10 including a magnet body that includes a rare earth compound, and a protective layer on the magnet body, having a first layer and a second layer in that order from the magnet body side, wherein the surface portion of the magnet body has a higher heavy rare earth element content than the interior of the magnet body that is surrounded by the surface portion, the first layer includes a rare earth oxide, the mass ratio of the heavy rare earth element being 1 or greater with respect to the light rare earth element, and the second layer includes an oxide containing iron and/or boron which is different from the rare earth oxide, the second layer having a lower rare earth oxide content than the first layer.

Abstract: An R-T-B based alloy strip including columnar crystals of an R2T14B 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 D1 and D2 are, 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?D2/D1?1.1/0.

Abstract: The present invention provides a rare earth based magnet including R2T14B main-phase crystal grains, and two-grain boundary phases between adjacent two R2T14B 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.

Abstract: The present invention provides a rare earth based magnet having a microstructure in which in a section of the R2T14B main-phase crystal grains, the number density of the fine products in the interior of (inside) the crystal grains is larger than that in the periphery of (outside) the crystal grains. That is, the rare earth based magnet includes R2T14B main-phase crystal grains and grain boundary phases formed between the R2T14B main-phase crystal grains. The R2T14B main-phase crystal grains include a substance where fine products are formed in the crystal grains. In the section of the main-phase crystal grains, when the crystal grains are divided into the interior of the crystal grains and the periphery of the crystal grains with a specific ellipse, the fine products are formed such that the number density in the interior is larger than that in the periphery.

Abstract: 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 R2T14B 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 Roundenss A, the shape of the main phase crystal grains is controlled such that the Roundness A becomes 0.24 or more.

Abstract: 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 ?m2 and the standard deviation of the area distribution being no greater than 3.

Abstract: An R-T-B based alloy strip containing dendritic crystals including a R2T14B phase, wherein on at least one surface, the average value for the widths of the dendritic crystals is no greater than 60 ?m, and the number of crystal nuclei in the dendritic crystals is at least 500 per 1 mm square area.

Abstract: An R-T-B sintered magnet 100 including particles containing an R2T14B phase, obtained using an R-T-B alloy strip containing crystal grains of an R2T14B phase, wherein the R-T-B alloy strip has, in a cross-section along the thickness direction, the crystal grains extending in a radial fashion from the crystal nuclei, the following inequality (1) being satisfied, where the average value of the lengths of the crystal grains on one side in the direction perpendicular to the thickness direction and the average value of the lengths on the other side opposite the one side are represented as D1 and D2, respectively, the mean particle diameter of the particles is 0.5 to 5 ?m, and essentially no heavy rare earth elements are present. 0.9?D2/D1?1.