A sintered ferrite magnet comprising (a) a ferrite phase having a hexagonal M-type magnetoplumbite structure comprising Ca, an element R which is at least one of rare earth elements and indispensably includes La, an element A which is Ba and/or Sr, Fe, and Co as indispensable elements, the composition of metal elements of Ca, R, A, Fe and Co being represented by the general formula of Ca.sub.1-x-yR.sub.xA.sub.yFe.sub.2n-zCo.sub.z, wherein the atomic ratios (1-x-y), x, y and z of these elements and the molar ratio n meet the relations of 0.3≦(1-x-y)≦0.65, 0.2≦x≦0.65, 0≦y≦0.2, 0.03≦z≦0.65, and 4≦n≦7, and (b) a grain boundary phase indispensably containing Si, the amount of Si being more than 1% by mass and 1.8% or less by mass (calculated as SiO.sub.2) based on the entire sintered ferrite magnet, and its production method.

In an embodiment, a magnet material includes a composition represented by R(Fe.sub.pM.sub.qCu.sub.r(Co.sub.1-aA.sub.a).sub.1-p-q-r).sub.z, where R is at least one element selected from rare earth elements, M is at least one element selected from Ti, Zr and Hf, A is at least one element selected from Ni, V, Cr, Mn, Al, Si, Ga, Nb, Ta, and W, p is 0.05≦p≦0.6, q is 0.005≦q≦0.1, r is 0.01≦r≦0.15, a is 0≦a≦0.2, z is 4≦z≦9, and a structure including an intragranular phase having a Th.sub.2Zn.sub.17 crystal phase and a grain boundary phase. An average crystal grain diameter of the intragranular phase is in a range of 20 to 500 nm, and an average thickness of the grain boundary phase is smaller than a magnetic domain wall thickness.

In an embodiment, a magnet material includes a composition represented by R(Fe.sub.pM.sub.qCu.sub.r(Co.sub.1-aA.sub.a).sub.1-p-q-r).sub.z, where R is at least one element selected from rare earth elements, M is at least one element selected from Ti, Zr and Hf, A is at least one element selected from Ni, V, Cr, Mn, Al, Si, Ga, Nb, Ta, and W, p is 0.05≦p≦0.6, q is 0.005≦q≦0.1, r is 0.01≦r≦0.15, a is 0≦a≦0.2, z is 4≦z≦9, and a structure including an intragranular phase having a Th.sub.2Zn.sub.17 crystal phase and a grain boundary phase. An average crystal grain diameter of the intragranular phase is in a range of 20 to 500 nm, and an average thickness of the grain boundary phase is smaller than a magnetic domain wall thickness.

In an embodiment, a permanent magnet includes a composition represented by a composition formula: R(Fe.sub.pM.sub.qCu.sub.r(Co.sub.1-sA.sub.s).sub.1-p-q-r).sub.z, where, R is at least one element selected from rare earth elements, M is at least one element selected from Ti, Zr, and Hf, A is at least one element selected from Ni, V, Cr, Mn, Al, Si, Ga, Nb, Ta, and W, 0.05≦p≦0.6, 0.005≦q≦0.1, 0.01≦r≦0.15, 0≦s≦0.2, and 4≦z≦9, and a two-phase structure of a Th.sub.2Zn.sub.17 crystal phase and a copper-rich phase. In a cross-section of the permanent magnet containing a crystal c axis of the Th.sub.2Zn.sub.17 crystal phase, an average distance between the copper-rich phases is 120 nm or less.

A permanent magnet of an embodiment includes: a composition represented by a composition formula: R(Fe.sub.pM.sub.qCu.sub.rCo.sub.1-p-q-r).sub.z, where R is at least one element selected from rare-earth elements, M is at least one element selected from Zr, Ti, and Hf, and relations of 0.3≦p≦0.4, 0.01≦q≦0.05, 0.01≦r≦0.1, and 7≦z≦8.5 (atomic ratio) are satisfied; and a structure including a cell phase having a Th.sub.2Zn.sub.17 crystal phase, and a cell wall phase existing to surround the cell phase. An average magnetization of the cell wall phase is 0.2 T or less.

A permanent magnet of an embodiment includes: a composition represented by a composition formula: R(Fe.sub.pM.sub.qCu.sub.rCo.sub.1-p-q-r).sub.z, where R is at least one element selected from rare-earth elements, M is at least one element selected from Zr, Ti, and Hf, and relations of 0.3≦p≦0.4, 0.01≦q≦0.05, 0.01≦r≦0.1, and 7≦z≦8.5 (atomic ratio) are satisfied; and a structure including a cell phase having a Th.sub.2Zn.sub.17 crystal phase, and a cell wall phase existing to surround the cell phase. An average magnetization of the cell wall phase is 0.2 T or less.

Nanocomposite magnetic materials, methods of manufacturing nanocomposite magnetic materials, and magnetic devices and systems using these nanocomposite magnetic materials are described. A nanocomposite magnetic material can be formed using an electro-infiltration process where nanomaterials (synthesized with tailored size, shape, magnetic properties, and surface chemistries) are infiltrated by electroplated magnetic metals after consolidating the nanomaterials into porous microstructures on planar substrates. The nanomaterials may be considered the inclusion phase, and the magnetic metals may be considered the matrix phase of the multi-phase nanocomposite.

A permanent magnet is expressed by a composition formula: R.sub.pFe.sub.qM.sub.rCu.sub.tCo.sub.100-p-q-r-t. The magnet comprises a metal structure including a main phase having a Th.sub.2Zn.sub.17 crystal phase and a grain boundary phase. The main phase includes a cell phase having the Th.sub.2Zn.sub.17 crystal phase and a Cu-rich phase. A section including a c-axis of the Th.sub.2Zn.sub.17 crystal phase has a first region in the crystal grain and a second region in the crystal grain, the first region is provided in the cell phase divided by the Cu-rich phase, the second region is provided within a range of not less than 50 nm nor more than 200 nm from the grain boundary phase in a direction perpendicular to an extension direction of the grain boundary phase, and a difference between a Cu concentration of the first region and a Cu concentration of the second region is 0.5 atomic percent or less.

A permanent magnet is expressed by a composition formula: R.sub.pFe.sub.qM.sub.rCu.sub.tCo.sub.100-p-q-r-t. The magnet comprises a metal structure including a main phase having a Th.sub.2Zn.sub.17 crystal phase and a grain boundary phase. The main phase includes a cell phase having the Th.sub.2Zn.sub.17 crystal phase and a Cu-rich phase. A section including a c-axis of the Th.sub.2Zn.sub.17 crystal phase has a first region in the crystal grain and a second region in the crystal grain, the first region is provided in the cell phase divided by the Cu-rich phase, the second region is provided within a range of not less than 50 nm nor more than 200 nm from the grain boundary phase in a direction perpendicular to an extension direction of the grain boundary phase, and a difference between a Cu concentration of the first region and a Cu concentration of the second region is 0.5 atomic percent or less.

A method for producing a sintered R-T-B based magnet of this disclosure includes the steps of preparing a plurality of sintered R-T-B based magnet bodies (R is at least one of rare earth elements and necessarily contains Nd and/or Pr; and T is at least one of transition metals and necessarily contains Fe); preparing a plurality of alloy powder particles having a size of 90 μm or less and containing a heavy rare earth element RH (the heavy rare earth RH is Tb and/or Dy) at a content of 20 mass % or greater and 80 mass % or less; loading the plurality of sintered R-T-B based magnet bodies and the plurality of alloy powder particles of a ratio of 2% by weight or greater and 15% by weight or less with respect to the plurality of sintered R-T-B based magnet bodies into a process chamber; and heating, while rotating and/or swinging, the process chamber to move the sintered R-T-B based magnet bodies and the alloy powder particles continuously or intermittently to perform an RH supply and diffusion process.