Abstract:
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.
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:
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≦1.1/0.9 (1)
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≦1.1/0.9 (1)
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 μm2 and the standard deviation of the area distribution being no greater than 3.
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 μm, and essentially no heavy rare earth elements are present. 0.9≦D2/D1≦1.1 (1)
Abstract:
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 ZrB2 crystal and an R—Cu-rich phase, a concentration of B in the grain boundary multiple junction containing both the ZrB2 crystal and the R—Cu-rich phase is from 5 to 20 atomic %, a concentration of Cu in the grain boundary multiple junction containing both the ZrB2 crystal and the R—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.
Abstract:
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 RL comprising at least Nd; and a heavy rare earth element RH, and the transition metal element T comprises Fe, Co, and Cu. Further, the intermediate layer comprises: an RL oxide phase comprising an oxide of the light rare earth element RL; and an RL—Co—Cu phase comprising the light rare element RL, Co, and Cu.
Abstract:
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.
Abstract:
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.