Neomax Co., Ltd.

Sumitomo Special Metals Co., Ltd.

Katsuya Taniguchi

Yuji Kaneko

Junichiro Baba

Takao Sekino

A method of making an alloy powder for an R&#x2014;Fe&#x2014;B-type rare earth magnet includes the steps of preparing a material alloy that is to be used for forming the R&#x2014;Fe&#x2014;B-type rare earth magnet and that has a chilled structure that constitutes about 2 volume percent to about 20 volume percent of the material alloy, coarsely pulverizing the material alloy for the R&#x2014;Fe&#x2014;B-type rare earth magnet by utilizing a hydrogen occlusion phenomenon to obtain a coarsely pulverized powder, finely pulverizing the coarsely pulverized powder and removing at least some of fine powder particles having particle sizes of about 1.0 &#x3bc;m or less from the finely pulverized powder, thereby reducing the volume fraction of the fine powder particles with the particle sizes of about 1.0 &#x3bc;m or less, and covering the surface of remaining ones of the powder particles with a lubricant after the step of removing has been performed.

Rare earth magnet and method for producing the magnet

The present invention provides a rare-earth sintered magnet exhibiting desirable magnetic properties in which the amount of Nd and/or Pr forming a non-magnetic phase in a grain boundary phase is reduced. Specifically, the present invention provides a rare-earth sintered magnet having a composition of (R1+R2)TQwhere R1 is at least one element selected from the group consisting of all rare-earth elements excluding La (lanthanum), Y (yttrium) and Sc (scandium); R2 is at least one element selected from the group consisting of La, Y and Sc; T is at least one element selected from the group consisting of all transition elements; Q is at least one element selected from the group consisting of B and C, and including, as a main phase, a crystal grain of an NdFeB crystalline structure, wherein: molar fractions x, y and z satisfy 8&#x2266;x&#x2266;18 at %, 0.1&#x2266;y&#x2266;3.5 at % and 3&#x2266;z&#x2266;20 at %, respectively; and a concentration of R2 is higher in at least a part of a grain boundary phase than in the main phase crystal grains.

Rare-earth sintered magnet and method of producing the same

A method of making an alloy powder for an R&mdash;Fe&mdash;B-type rare earth magnet includes the steps of preparing a material alloy that is to be used for forming the R&mdash;Fe&mdash;B-type rare earth magnet and that has a chilled structure that constitutes about 2 volume percent to about 20 volume percent of the material alloy, coarsely pulverizing the material alloy for the R&mdash;Fe&mdash;B-type rare earth magnet by utilizing a hydrogen occlusion phenomenon to obtain a coarsely pulverized powder, finely pulverizing the coarsely pulverized powder and removing at least some of fine powder particles having particle sizes of about 1.0 &mgr;m or less from the finely pulverized powder, thereby reducing the volume fraction of the fine powder particles with the particle sizes of about 1.0 &mgr;m or less, and covering the surface of remaining ones of the powder particles with a lubricant after the step of removing has been performed.

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Sanda, Japan

Katsuya Taniguchi