In one embodiment, a permanent magnet includes a sintered compact having a composition expressed by a composition formula: Rp1Feq1Mr1Cus1Co100-p1-q1-r1-s1 (R is a rare-earth element, M is at least one element selected from Zr, Ti, and Hf, 10p113.3 at %, 25q140.0 at %, 0.88r15.4 at %, and 3.5s113.5 at %). The sintered compact includes crystal grains and a Cu-rich phase. The crystal grains are composed of a main phase including a Th.sub.2Zn.sub.17 crystal phase. The Cu-rich phase has a composition with a high Cu concentration and an average thickness of 0.05 m or more and 2 m or less.

In one embodiment, a permanent magnet includes a sintered compact having a composition expressed by a composition formula: Rp1Feq1Mr1Cus1Co100-p1-q1-r1-s1 (R is a rare-earth element, M is at least one element selected from Zr, Ti, and Hf, 10p113.3 at %, 25q140.0 at %, 0.88r15.4 at %, and 3.5s113.5 at %). The sintered compact includes crystal grains and a Cu-rich phase. The crystal grains are composed of a main phase including a Th.sub.2Zn.sub.17 crystal phase. The Cu-rich phase has a composition with a high Cu concentration and an average thickness of 0.05 m or more and 2 m or less.

There is provided a composite material containing magnetic powder and a polymeric material including the powder in a dispersion state, wherein a content of the magnetic powder with respect to the whole composite material is more than 50% by volume and 75% by volume or less, a saturation magnetic flux density of the composite material is 0.6 T or more, and a relative magnetic permeability of the composite material is more than 20 and is 35 or less. It is preferable that a density ratio of the magnetic powder should be 0.38 or more and 0.65 or less. The density ratio is set to be an apparent density/a true density. Moreover, it is preferable that the magnetic powder should include a plurality of particles constituted of the same material.

There is provided a composite material containing magnetic powder and a polymeric material including the powder in a dispersion state, wherein a content of the magnetic powder with respect to the whole composite material is more than 50% by volume and 75% by volume or less, a saturation magnetic flux density of the composite material is 0.6 T or more, and a relative magnetic permeability of the composite material is more than 20 and is 35 or less. It is preferable that a density ratio of the magnetic powder should be 0.38 or more and 0.65 or less. The density ratio is set to be an apparent density/a true density. Moreover, it is preferable that the magnetic powder should include a plurality of particles constituted of the same material.

In one embodiment, a permanent magnet includes a sintered compact including: a composition expressed by a composition formula: R.sub.pFe.sub.qM.sub.rCu.sub.sCo.sub.100-p-q-r-s (R is at least one element selected from rare-earth elements, M is at least one element selected from Zr, Ti, and Hf, 10p13.3 at %, 25q40 at %, 0.87r5.4 at %, and 3.5s13.5 at %); and a metallic structure having a main phase including a Th.sub.2Zn.sub.17 crystal phase, and an R-M-rich phase containing the element R whose concentration is 1.2 times or more an R concentration in the main phase and the element M whose concentration is 1.2 times or more an M concentration in the main phase. A volume fraction of the R-M-rich phase in the metallic structure is from 0.2% to 15%.

In one embodiment, a permanent magnet includes a sintered compact including: a composition expressed by a composition formula: R.sub.pFe.sub.qM.sub.rCu.sub.sCo.sub.100-p-q-r-s (R is at least one element selected from rare-earth elements, M is at least one element selected from Zr, Ti, and Hf, 10p13.3 at %, 25q40 at %, 0.87r5.4 at %, and 3.5s13.5 at %); and a metallic structure having a main phase including a Th.sub.2Zn.sub.17 crystal phase, and an R-M-rich phase containing the element R whose concentration is 1.2 times or more an R concentration in the main phase and the element M whose concentration is 1.2 times or more an M concentration in the main phase. A volume fraction of the R-M-rich phase in the metallic structure is from 0.2% to 15%.

A superconducting magnet and method for making a superconducting magnet are presented. The superconducting magnet is made by forming a coil from windings of a first wire comprising a reacted MgB.sub.2 monofilament, filling a cavity of a stainless steel billet with a Mg+B powder. Monofilament ends of the first wire and a similar second wire are sheared at an acute angle and inserted into the billet. A copper plug configured to partially fill the billet cavity is inserted into the billet cavity. A portion of the billet adjacent to the plug and the wires is sealed with a ceramic paste.

A superconducting magnet and method for making a superconducting magnet are presented. The superconducting magnet is made by forming a coil from windings of a first wire comprising a reacted MgB.sub.2 monofilament, filling a cavity of a stainless steel billet with a Mg+B powder. Monofilament ends of the first wire and a similar second wire are sheared at an acute angle and inserted into the billet. A copper plug configured to partially fill the billet cavity is inserted into the billet cavity. A portion of the billet adjacent to the plug and the wires is sealed with a ceramic paste.

In one embodiment, a permanent magnet includes: a composition expressed by R.sub.pFe.sub.qM.sub.rCu.sub.sCo.sub.100-p-q-r-s (R is a rare-earth element, M is at least one element selected from Zr, Ti, and Hf, 10.8p13.5 at %, 28q40 at %, 0.88r7.2 at %, and 3.5s13.5 at %); and a metallic structure including a cell phase having a Th.sub.2Zn.sub.17 crystal phase, and a cell wall phase. A Cu concentration in the cell wall phase is in a range from 30 at % to 70 at %.

A grain-oriented electrical steel sheet subjected to magnetic domain refining by linearly introducing strains in a direction intersecting a rolling direction of the steel sheet repeatedly with intervals in the rolling direction, wherein if a repeating interval of the strains in the rolling direction is d (mm) and, when the steel sheet is placed on a flat surface, a mean value of difference between a height from the flat surface in linear strain-introduced areas of a steel sheet surface and a height from the flat surface in intermediate points between adjacent linear strain-introduced areas is h (mm), then the ratio h/d of the h to the d is 0.0025 or more and 0.015 or less.