Hitachi Metals, Ltd.

Hideyuki Morimoto

Tomoori Odaka

Koshi Yoshimura

Kohshi Yoshimura

Masao Noumi

Shigeru Takaki

Shinichiro Sakashita

Akiyasu Ohta

A rare-earth sintered magnet includes 12.0 at % to 15.0 at % of rare-earth element(s), which is at least one element selected from the group consisting of Nd, Pr, Gd, Tb, Dy and Ho and at least 50% of which is Nd and/or Pr; 5.5 at % to 8.5 at % of boron (B); a predetermined percentage of additive metal A; and iron (Fe) and inevitably contained impurities as the balance. The predetermined percentage of additive metal A includes at least one of 0.005 at % to 0.30 at % of silver (Ag), 0.005 at % to 0.40 at % of nickel (Ni), and 0.005 at % to 0.20 at % of gold (Au).

Rare earth sintered magnet and method for production thereof

In an R&#x2014;Fe&#x2014;B based rare-earth sintered magnet according to the present invention, at a depth of 20 &#x3bc;m under the surface of its magnet body, crystal grains of an RFeB type compound have an (RLRH)FeB (where 0.2&#x2266;x&#x2266;0.75) layer with a thickness of 1 nm to 2 &#x3bc;m in their outer periphery. In this case, the light rare-earth element RL is at least one of Nd and Pr, and the heavy rare-earth element RH is at least one element selected from the group consisting of Dy, Ho and Tb.

R-Fe-B type rare earth sintered magnet and process for production of the same

A sintered R&#x2014;Fe&#x2014;B based rare-earth magnet bodyincluding, as a main phase, crystal grains of an RFeB type compound that includes a light rare-earth element RL, which is Nd and/or Pr, as a major rare-earth element R is provided. A bulk bodyincluding a heavy rare-earth element RH, which is at least one of Dy, Ho and Tb is also provided. The sintered magnet bodyand the bulk bodyare arranged in a processing chamberwith a vapor control memberinterposed between the sintered magnet bodyand the bulk body. And the inside of the processing chamberis heated to a temperature of 700&#xb0; C. to 1000&#xb0; C., thereby diffusing the heavy rare-earth element RH inside the sintered magnet bodywhile supplying the heavy rare-earth element RH from the bulk bodyto the surface of the sintered magnet bodyvia the vapor control member

Process for production of R-Fe-B-based rare earth sintered magnet, and steam control member

In a method for producing an R&#x2014;Fe&#x2014;B based rare-earth sintered magnet according to the present invention, first, provided is an R&#x2014;Fe&#x2014;B based rare-earth sintered magnet body including, as a main phase, crystal grains of an RFeB type compound that includes a light rare-earth element RL, which is at least one of Nd and Pr, as a major rare-earth element R. Thereafter, the sintered magnet body is heated while a heavy rare-earth element RH, which is at least one element selected from the group consisting of Dy, Ho and Tb, is supplied to the surface of the sintered magnet body, thereby diffusing the heavy rare-earth element RH into the rare-earth sintered magnet body.

R&#x2014;Fe&#x2014;B rare earth sintered magnet and method for producing same

First, an R&#x2014;Fe&#x2014;B based rare-earth sintered magnet body including, as a main phase, crystal grains of an RFeB type compound that includes a light rare-earth element RL, which is at least one of Nd and Pr, as a major rare-earth element R is provided. Next, an M layer, including a metallic element M that is at least one element selected from the group consisting of Al, Ga, In, Sn, Pb, Bi, Zn and Ag, is deposited on the surface of the sintered magnet body and then an RH layer, including a heavy rare-earth element RH that is at least one element selected from the group consisting of Dy, Ho and Tb, is deposited on the M layer. Thereafter, the sintered magnet body is heated, thereby diffusing the metallic element M and the heavy rare-earth element RH from the surface of the magnet body deeper inside the magnet.

R-F	e-B rare-earth sintered magnet and process for producing the same

An R&#x2014;Fe&#x2014;B based anisotropic sintered magnet according to the present invention has, as a main phase, an RFeB type compound that includes a light rare-earth element RL (which is at least one of Nd and Pr) as a major rare-earth element R, and also has a heavy rare-earth element RH (which is at least one element selected from the group consisting of Dy and Tb). In the crystal lattice of the main phase, the c-axis is oriented in a predetermined direction. The magnet includes a portion in which at least two peaks of diffraction are observed within a 2&#x3b8; range of 60.5 degrees to 61.5 degrees when an X-ray diffraction measurement is carried out using a CuK &#x3b1; ray on a plane that is located at a depth of 500 &#x3bc;m or less under a pole face of the magnet and that is parallel to the pole face.

R-Fe-B anisotropic sintered magnet

An R&#x2014;Fe&#x2014;B based rare-earth sintered magnet according to the present invention includes, as a main phase, crystal grains of an RFeB type compound that includes Nd, which is a light rare-earth element, as a major rare-earth element R. The magnet includes a heavy rare-earth element RH (which is at least one of Dy and Tb) that has been introduced through the surface of the sintered magnet by diffusion. The magnet has a region in which the concentration of the heavy rare-earth element RH in a grain boundary R-rich phase is lower than at the surface of the crystal grains of the RFeB type compound but higher than at the core of the crystal grains of the RFeB type compound.

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Osaka, Japan

Hideyuki Morimoto