A sintered magnet contains SmFeN-based crystal grains and has high coercivity; and a magnetic powder is capable of forming a sintered magnet without lowering the coercivity even if heat is generated in association with the sintering. A sintered magnet comprises a crystal phase composed of a plurality of SmFeN-based crystal grains and a nonmagnetic metal phase present between the SmFeN crystal grains adjacent to each other, wherein a ratio of Fe peak intensity I.sub.Fe to SmFeN peak intensity I.sub.SmFeN measured by an X-ray diffraction method is 0.2 or less. A magnetic powder comprises SmFeN-based crystal particles and a nonmagnetic metal layer covering surfaces of the SmFeN crystal particles.

A method for producing a rare earth magnet includes a molding step of supplying a metal powder including a rare earth element into a mold 2 to form a green compact 10; an orientation step of applying a pulse magnetic field H to the green compact 10 held in the mold 2 to orient the metal powder included in the green compact 10; and a sintering step of sintering the green compact 10 separated from the mold 2 after the orientation step. At least one part of the mold 2 is formed from a resin, and the green compact having a density adjusted to 3.0 g/cm.sup.3 or more and 4.4 g/cm.sup.3 or less is sintered.

A rare earth permanent magnet includes a main phase composed of a main phase particle and a grain boundary present among a plurality of the main phase particles. The grain boundary includes a region whose electric resistance is higher than that of the main phase.

The present invention provides a ferrite sintered magnet comprising (1) main phase grains containing a ferrite having a hexagonal structure, (2) two-grain boundaries formed between two of the main phase grains, and (3) multi-grain boundaries surrounded by three or more of the main phase grains. The above ferrite sintered magnet comprises Ca, R, Sr, Fe and Co, with R being at least one element selected from the group consisting of rare earth elements and Bi, and comprising at least La. The number Nm of the above main phase grains and the number Ng of the above multi-grain boundaries in the cross section including the direction of the easy magnetization axis of the above ferrite sintered magnet satisfy the formula (1A):

50%Nm/(Nm+Ng)65%(1A).

A method for manufacturing a raw magnet includes manufacturing a first raw form from a first magnetic base material; manufacturing a second raw form from a second magnetic base material; and applying an external magnetic field to at least one raw form selected from a group consisting of the first raw form and the second raw form during and/or after manufacturing of the raw form. A third raw form is manufactured from the first raw form and the second raw form by joining them together. The third raw form is sintered and the raw magnet is obtained.

A rare earth permanent magnet that is high in residual magnetization and coercivity is obtained and includes R and T. A main phase of crystal grains having an Nd.sub.5Fe.sub.17 type crystal structure is included. In an X-ray diffraction profile drawn by performing an XRD measurement for a rare earth permanent magnet, peaks of detected intensity are present in specific ranges. In which the detected intensity of the peak with the highest detected intensity in the range of 41.60<2()<42.80 is set as , the detected intensity of the peak with the highest detected intensity in the range of 34.38<2()<34.64 is set as , and the detected intensity of the peak with the highest detected intensity in the range of 38.70<2()<41.20 is set as , 0.38</<0.70 and 0.45</<0.70 are established. The peak with the highest detected intensity in the range of 34.38<2()<34.64 is a peak derived from the Nd.sub.5Fe.sub.17 type crystal structure.

The invention provides an RFeB sintered magnet consisting essentially of 12-17 at % of Nd, Pr and R, 0.1-3 at % of M.sub.1, 0.05-0.5 at % of M.sub.2, 4.8+2*m to 5.9+2*m at % of B, and the balance of Fe, containing R.sub.2(Fe,(Co)).sub.14B intermetallic compound as a main phase, and having a core/shell structure that the main phase is covered with grain boundary phases. The sintered magnet exhibits a coercivity of at least 10 kOe despite a low or nil content of Dy, Tb and Ho.

A step of, while an RLM alloy powder (where RL is Nd and/or Pr; M is one or more elements selected from among Cu, Fe, Ga, Co, Ni and Al) and an RH oxide powder (where RH is Dy and/or Tb) are present on the surface of a sintered R-T-B based magnet, performing a heat treatment at a sintering temperature of the sintered R-T-B based magnet or lower is included. The RLM alloy contains RL in an amount of 50 at % or more, and the melting point of the RLM alloy is equal to or less than the temperature of the heat treatment. The heat treatment is performed while the RLM alloy powder and the RH oxide powder are present on the surface of the sintered R-T-B based magnet at a mass ratio of RLM alloy:RH oxide=9.6:0.4 to 5:5.

An R-T-B based sintered magnet includes R.sub.2T.sub.14B crystal grains. A grain boundary formed by the two or more adjacent R.sub.2T.sub.14B crystal grains includes an RNOC concentrated part having higher concentrations of R, N, O, and C than those in the R.sub.2T.sub.14B crystal grains. R of the RNOC concentrated part includes Y. A ratio of Y atom to R atom in the RNOC concentrated part is 0.65 or more and 1.00 or less. A ratio of O atom to R atom in the RNOC concentrated part is more than 0 and 0.20 or less. A ratio of N atom to R atom in the RNOC concentrated part is 0.03 or more and 0.15 or less.

The present invention provides a method for preparing a rare earth permanent magnet material. The preparation method of the present invention comprises atomizing spray process and infiltrating process, wherein the atomizing-sprayed sintered rare earth magnet is placed in a closed container before infiltrating. Through the atomizing spray process a solution containing a heavy rare earth element is coated on the surface of a sintered R1-Fe(Co)B-A-X-M rare earth magnet, and after baking, heat treatment is performed to infiltrate the sprayed heavy rare earth element to the grain boundary phase of the sintered rare earth magnet. This method decreases the amount of a heavy rare earth element used, increases the coercive force of magnets with a little decrease of remanence, decreases the remanence temperature coefficient and coercive force temperature coefficient of the magnet, and improves resistance of the magnet against demagnetization at a high temperature.