Shin-etsu Chemical Co., Ltd.

Masayuki Kamata

Koichi Hirota

Hajime Nakamura

Tadao Nomura

Tetsuya Kume

Hiroaki Nagata

Takahiro Hashimoto

Kazuki Otsuka

Provided are an anisotropic rare earth sintered magnet having a ThMn-type crystal compound as a main phase and exhibits good magnetic characteristics, and a method for producing it. The anisotropic rare earth sintered magnet has a composition of a formula (RZr)(FeCo)(MM)OC(where R is one or more kinds selected from rare earth elements and indispensably includes Sm, Mis one or more kinds of elements selected from the group consisting of V, Cr, Mn, Ni, Cu, Zn, Ga, Al, and Si, Mis one or more kinds of elements selected from the group consisting of Ti, Nb, Mo, Hf, Ta, and W, and v, w, x, y, a, b, and c each satisfy 7≤v≤15 at %, 4≤w≤20 at %, 0.2≤x≤4 at %, 0.2≤y≤2 at %, 0≤a≤0.2, 0≤b≤0.5, and 0≤c≤0.9), which contains a main phase of a ThMn-type crystal compound in an amount of 80% by volume or more with the average crystal particle diameter of the main phase being 1 μm or more, which contains an R oxycarbide in the grain boundary area, and which has a density of 7.3 g/cmor more. The production method for the anisotropic rare earth sintered magnet includes grinding an alloy that contains a ThMn-type crystal compound phase but does not contain an oxycarbide, then molding it in a mode of pressure powder molding with magnetic field application thereto to give a molded article, and thereafter sintering it at a temperature of 800° C. or higher and 1400° C. or lower to form an oxycarbide in the grain boundary area.

Anisotropic rare earth sintered magnet and method for producing the same

The invention provides an anisotropic rare earth sintered magnet having an NdFeB-type compound crystal as a main phase and containing Ce, and exhibiting good magnetic characteristics, and a method for producing the same. The anisotropic rare earth sintered magnet has a composition of a formula R(FeCo)BM(where R is two or more kinds of elements selected from rare earth elements and indispensably including Nd and Ce), in which the main phase is formed of an NdFeB-type compound crystal, main phase grains such that the Ce/R' ratio in the center part of the grains (where R′ is one or more kinds of elements selected from rare earth elements and indispensably including Nd) is lower than the Ce/R′ ratio in the outer shell part thereof exist, and a Ce-containing R′-rich phase and a Ce-containing R′(Fe,Co)phase exist in the grain boundary part. The production method is for producing the anisotropic rare earth sintered magnet.

An R&#x2014;Fe&#x2014;B base sintered magnet is provided consisting essentially of R (which is at least two rare earth elements and essentially contains Nd and Pr), Mwhich is at least two of Si, Al, Mn, Ni, Cu, Zn, Ga, Ge, Pd, Ag, Cd, In, Sn, Sb, Pt, Au, Hg, Pb, and Bi, Mwhich is at least one of Ti, V, Cr, Zr, Nb, Mo, Hf, Ta, and W, boron, and the balance of Fe, and containing an intermetallic compound R(Fe,(Co))B as a main phase. The magnet contains an R&#x2014;Fe(Co)-Mphase as a grain boundary phase, the R&#x2014;Fe(Co)-Mphase contains A phase which is crystalline with crystallites of at least 10 nm formed at grain boundary triple junctions, and B phase which is amorphous and/or nanocrystalline with crystallites of less than 10 nm formed at intergranular grain boundaries and optionally grain boundary triple junctions.

R-Fe-B sintered magnet and making method

An R&#x2014;(Fe,Co)&#x2014;B base sintered magnet consisting essentially of 12-17 at % of R containing Nd and Pr, 0.1-3 at % of M(typically Si), 0.05-0.5 at % of M(typically Ti), B, and the balance of Fe, and containing R(Fe,Co)B as a main phase has a coercivity of at least 10 kOe. The magnet contains a Mboride phase at a grain boundary triple junction, and has a core/shell structure that the main phase is covered with a grain boundary phase. The grain boundary phase is composed of an amorphous and/or nanocrystalline R'&#x2014;(Fe,Co)&#x2014;M&#x2032; phase consisting essentially of 25-35 at % of R&#x2032; containing Pr, 2-8 at % of M&#x2032; (typically Si), up to 8 at % of Co, and the balance of Fe. A coverage of the main phase with the R&#x2032;&#x2014;(Fe,Co)&#x2014;M&#x2032; phase is at least 50%, and the bi-granular grain boundary phase has a width of at least 50 nm.

R-(Fe, Co)-B sintered magnet and making method

The invention provides an R&#x2014;Fe&#x2014;B sintered magnet consisting essentially of 12-17 at % of Nd, Pr and R, 0.1-3 at % of M, 0.05-0.5 at % of M, 4.8+2*m to 5.9+2*m at % of B, and the balance of Fe, containing R(Fe,(Co))B 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.

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Echizen, Japan

Masayuki Kamata