Shin-etsu Chemical Co., Ltd.

Mikio Yoshida

Koichi Hirota

Hiroki Iida

Hajime Nakamura

Shigeru Sakai

Tetsuya Ohashi

Kazuya Fukui

Akihiro Yoshinari

Michihiro Oida

Provided is an R—Fe—B-based sintered magnet which has a composition comprising R (wherein R represents at least one element selected from rare earth elements, and essentially contains Nd), B, M (wherein M represents at least one element selected from Si, Al, Mn, Ni, Co, Cu, Zn, Ga, Ge, Pd, Ag, Cd, In, Sn, Sb, Pt, Au, Hg, Pb and Bi), X (wherein X represents at least one element selected from Ti, Zr, Hf, Nb, V and Ta) and C, with a remainder comprising Fe, O and unavoidable impurities, and has a main phase comprising RFeB and a grain boundary phase comprising an R—C phase having a higher R concentration and a higher C concentration than those in the main phase, the R—Fe—B-based sintered magnet being characterized in that the area ratio of the R—C phase in a cross section of the magnet is more than 0% and 0.5% or less.

R—Fe—B-based sintered magnet

Provided is a rare earth sintered magnet in which a multi-layer main phase particle having multiple layers including a layer 1 having Rconcentration, represented by at %, higher than that of a center of the particle, a layer 2 which is formed on the outside of the layer 1 and has Rconcentration lower than that of the layer 1, and a layer 3 which is formed on the outside of the layer 2 and has Rconcentration higher than that of the layer 2 is present at least in a portion in the vicinity of a surface of the main phase particle within at least 500 &#x3bc;m from a surface of the sintered magnet body.

Rare earth sintered magnet

A polymeric flocculant is added to an aqueous solution comprising an organic acid and a basic compound to form a water-soluble fluid suitable for use in machining of rare earth magnet.

Water-soluble fluid for use in machining of rare earth magnet

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Echizen, Japan

Mikio Yoshida