Abstract: The present invention relates to a sintered magnet including a main phase including an R2T14B compound, in which the element R is a rare earth element, and the element T is Fe or includes Fe and Co with which a part of Fe is substituted, and a grain boundary phase which is present at a grain boundary triple junction and contains a rare earth element including a heavy rare earth element, Cu and the element T, in which a content of the rare earth element in the grain boundary phase as a whole is 55 mass % or more, and a Cu-rich region containing 8 mass % or more of Cu accounts for 9 vol % or more of the grain boundary phase.

Abstract: A method for producing an RFeB system sintered magnet according to the present invention includes: a process (S1) of preparing a lump of HDDR-treated raw material alloy that contains a polycrystalline substance including crystal grains having an average grain size of 1 ?m or less in terms of an equivalent circle diameter calculated from an electron micrograph image, by an HDDR treatment including steps of heating a lump of RFeB system alloy containing 26.5 to 29.5% by weight of the rare-earth element R, in a hydrogen atmosphere at a temperature between 700 and 1,000° C., and changing the atmosphere to vacuum while maintaining the temperature within a range from 750 to 900° C.; a process (S2) of preparing a lump of raw material alloy having a high rare-earth content by heating the lump of HDDR-treated raw material alloy at a temperature between 700 and 950° C.

Abstract: A method for producing a NdFeB system sintered magnet. The method includes: a hydrogen pulverization process, in which coarse powder of a NdFeB system alloy is prepared by coarsely pulverizing a lump of NdFeB system alloy by making this lump occlude hydrogen; a fine pulverization process, in which fine powder is prepared by performing fine pulverization for further pulverizing the coarse powder; a filling process, in which the fine powder is put into a filling container; an orienting process, in which the fine powder in the filling container is oriented; and a sintering process, in which the fine powder after the orienting process is sintered as held in the filling container. The processes from hydrogen pulverization through orienting are performed with neither dehydrogenation heating nor evacuation each for desorbing hydrogen occluded in the hydrogen pulverization process. The processes from hydrogen pulverization through sintering are performed in an oxygen-free atmosphere.

Abstract: An RFeB system sintered magnet which does not contain a heavy rare-earth element RH (Dy, Tb and Ho) in a practically effective amount and yet is suited for applications in which the magnet undergoes a temperature increase during its use. The RFeB system sintered magnet contains at least one element selected from the group consisting of Nd and Pr as a rare-earth element R in addition to Fe and B while containing none of Dy, Tb and Ho, the magnet having a temperature characteristic value t(100-23) which satisfies ?0.58<t(100-23)<0, where t(100-23) is defined by the following equation: t ( 100 - 23 ) = H cj ? ( 100 ) - H cj ? ( 23 ) ( 100 - 23 ) × H cj ? ( 23 ) × 100 using Hcj(23) which is the value of the coercivity at a temperature of 23° C. and Hcj(100) which is the value of the coercivity at a temperature of 100° C.

Abstract: A method for producing an RFeB system sintered magnet with the main phase grains having a grain size of 1 ?m or less with a considerably equal grain size, including: preparing a shaped body oriented by a magnetic field and sintering the shaped body, wherein the shaped body is prepared using an alloy powder of an RFeB material having a particle size distribution with an average value of 1 ?m or less in terms of a circle-equivalent diameter determined from a microscope image, the alloy powder obtained by pulverizing coarse particles having fine crystal grain, each coarse particle having grains of the RFeB material formed inside, the crystal grains having a crystal grain size distribution with an average value of 1 ?m or less in terms of the circle-equivalent diameter determined from a microscope image, and 90% by area or more of the crystal grains being separated from each other.

Abstract: A method for producing a NdFeB system sintered magnet. The method includes: a hydrogen pulverization process, in which coarse powder of a NdFeB system alloy is prepared by coarsely pulverizing a lump of NdFeB system alloy by making this lump occlude hydrogen; a fine pulverization process, in which fine powder is prepared by performing fine pulverization for further pulverizing the coarse powder; a filling process, in which the fine powder is put into a filling container; an orienting process, in which the fine powder in the filling container is oriented; and a sintering process, in which the fine powder after the orienting process is sintered as held in the filling container. The processes from hydrogen pulverization through orienting are performed with neither dehydrogenation heating nor evacuation each for desorbing hydrogen occluded in the hydrogen pulverization process. The processes from hydrogen pulverization through sintering are performed in an oxygen-free atmosphere.