Abstract: The present invention relates to a method for producing an RFeB-based magnet, the method including: a base material preparation step of preparing a base material made of a sintered body of an RFeB-based alloy or a hot-deformed body of the RFeB-based alloy; an adhesion substance preparation step of preparing an adhesion substance containing an RHdCu alloy that includes Cu and a heavy rare earth element RHd to be diffused and that has a content of Cu of 20 mass % or more and 40 mass % or less; an adhesion step of adhering the adhesion substance to a surface of the base material; and a heating step of heating the base material to which the adhesion substance has been adhered to a predetermined temperature at which the heavy rare earth element RHd to be diffused is diffused into the base material through a grain boundary of the base material.

Abstract: The present invention relates to an R-T-B-based sintered magnet including: a rare earth element R; a metal element T which is Fe, or includes Fe and Co with which a part of Fe is substituted; boron; and a boride forming element M which is a metal element other than rare earth elements and the metal element T and forms a boride, in which the R-T-B-based sintered magnet includes: a main phase which includes a crystal grain of an R-T-B-based alloy; and a boride phase which includes a compound phase based on the boride of the boride forming element M, and is generated on a preferential growth plane of the crystal grain of the main phase.

Abstract: The present invention relates to an RFeB-based sintered magnet having a composition including: 24-31% by mass of at least one element selected from the group consisting of Nd, Pr, La and Ce; 0.1-6.5% by mass of at least one element selected from the group consisting of Dy and Tb; 0.8-1.4% by mass of B; 0.03-0.2% by mass of at least one element selected from the group consisting of Zr, Ti, Hf and Nb; 0.8-5.5% by mass of Co; 0.1-1.0% by mass of Cu; and 0.1-1.0% by mass of Al, with a remainder being Fe and unavoidable impurities, in which the composition has a total content of Cu and Al being higher than 0.5% by mass.

Abstract: The present invention relates to an RFeB sintered magnet containing: 28% to 33% by mass of a rare-earth element R, 0% to 2.5% by mass of Co (cobalt) (i.e., Co may not be contained), 0.3% to 0.7% by mass of Al (aluminum), 0.9% to 1.2% by mass of B (Boron), and less than 1,500 ppm of O (oxygen), with the balance being Fe, containing an RFeAl phase having an R6Fe14-xAlx structure in a crystal grain boundary, and having a coercivity of 16 kOe or more.

Abstract: The present invention relates to an RFeB sintered magnet containing: 28% to 33% by mass of a rare-earth element R, 0% to 2.5% by mass of Co (cobalt) (i.e., Co may not be contained), 0.3% to 0.7% by mass of Al (aluminum), 0.9% to 1.2% by mass of B (Boron), and less than 1,500 ppm of O (oxygen), with the balance being Fe, containing an RFeAl phase having an R6Fe14-xAlx structure in a crystal grain boundary, and having a coercivity of 16 kOe or more.

Abstract: The present invention relates to an R-T-B-based sintered magnet including: a rare earth element R; a metal element T which is Fe, or includes Fe and Co with which a part of Fe is substituted; boron; and a boride forming element M which is a metal element other than rare earth elements and the metal element T and forms a boride, in which the R-T-B-based sintered magnet includes: a main phase which includes a crystal grain of an R-T-B-based alloy; and a boride phase which includes a compound phase based on the boride of the boride forming element M, and is generated on a preferential growth plane of the crystal grain of the main phase.

Abstract: The present invention relates to an RFeB-based sintered magnet having a composition including: 24-31% by mass of at least one element selected from the group consisting of Nd, Pr, La and Ce; 0.1-6.5% by mass of at least one element selected from the group consisting of Dy and Tb; 0.8-1.4% by mass of B; 0.03-0.2% by mass of at least one element selected from the group consisting of Zr, Ti, Hf and Nb; 0.8-5.5% by mass of Co; 0.1-1.0% by mass of Cu; and 0.1-1.0% by mass of Al, with a remainder being Fe and unavoidable impurities, in which the composition has a total content of Cu and Al being higher than 0.5% by mass.

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: 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.