Tdk Corporation

Showa Denko K.k.

Other

Shinya Fujito

Koichi Yajima

Hiroshi Hasegawa

Yoichi Hirose

Shiro Sasaki

Kazuo Sato

Kazuya Sakamoto

Tetsuya Hidaka

Koji Mitake

Motohisa Murata

Shinya Hashimoto

Katashi Takebuchi

Motoaki Hosako

A sintered rare earth magnet rotating machine and method improve temperature properties and strength having an excellent corrosion resistance. The sintered rare earth magnet includes at least a main phase composed of RTB (R represents at least one rare earth element of Nd, Pr or both and T represents at least one transition metal element including Fe or Fe and Co) compound and a grain boundary phase containing a higher proportion of R than the main phase, wherein the main phase includes a heavy rare earth element (one of Dy, Tb or both), at least part of main phase grains of the main phase included in the sintered rare earth magnet includes at least the following regions, low, high and intermediate concentration regions. These regions exist in order of low, high, and intermediate concentration regions, from low concentration region towards the grain boundary phase in the main phase grains.

Sintered rare earth magnet, method of producing the same, and rotating machine

An alloy used for the production of a rare-earth magnet alloy, particularly the boundary-phase alloy in the two-alloy method is provided to improve the crushability. The Alloy consists of (a) from 35 to 60% of Nd, Dy and/or Pr, and the balance being Fe, or (b) from 35 to 60% of Nd, Dy and/or Pr, and at least one element selected from the group consisting of 35% by weight or less of Co, 4% by weight or less of Cu, 3% by weight or less of Al and 3% by weight or less of Ga, and the balance being Fe. The volume fraction of R,Fe,phase (Fe may be replaced with Cu, Co, Al or Ga) is 25% or more in the alloy and the average size of an R,Fe,phase is 20 &mgr;m or less. The alloy can be produced by a centrifugal casting at an average accumulating rate of melt at 0.1 cm/second or less.

Alloy used for production of a rare-earth magnet and method for producing the same

An alloy used for the production of a rare-earth magnet alloy, particularly the boundary-phase alloy in the two-alloy method is provided to improve the crushability. The alloy consists of (a) from 35 to 60% of Nd, Dy and/or Pr, 1% or less of B, and the balance being Fe, or (b) from 35 to 60% of Nd, Dy and/or Pr, 1% or less of B, and at least one element selected from the group consisting of 35% by weight or less of Co, 4% by weight or less of Cu, 3% by weight or less of Al and 3% by weight or less of Ga, and the balance being Fe. The total volume fraction of R.sub.2 Fe.sub.17 and R.sub.2 Fe.sub.14 B phases (Fe may be replaced with Cu, Co, Al or Ga) is 25% or more in the alloy. The average size of each of the R.sub.2 Fe.sub.17 and R.sub.2 Fe.sub.14 B phases is 20 .mu.m or less. The alloy can be produced by a centrifugal casting at an average accumulating rate of melt at 0.1 cm/second or less.

Alloy used for production of a rare-earth magnet and method for

An alloy used for the production of a rare-earth magnet alloy, particularly the boundary-phase alloy in the two-alloy method is provided to improve the crushability. The Alloy consists of (a) from 35 to 60% of Nd, Dy and/or Pr, and the balance being Fe, or (b) from 35 to 60% of Nd, Dy and/or Pr, and at least one element selected from the group consisting of 35% by weight or less of Co, 4% by weight or less of Cu, 3% by weight or less of Al and 3% by weight or less of Ga, and the balance being Fe. The volume fraction of R.sub.2 Fe.sub.17 phase (Fe may be replaced with Cu, Co, Al or Ga) is 25% or more in the alloy and the average size of an R.sub.2 Fe.sub.17 phase is 20 .mu.m or less. The alloy can be produced by a centrifugal casting at an average accumulating rate of melt at 0.1 cm/second or less.

A permanent magnet which contains R, T and B as main ingredients wherein R is Y or a rare earth element and T is Fe or Fe and Co and has a primary phase of R.sub.2 T.sub.14 B is produced by compacting a mixture of 60 to 95 wt % of a primary phase-forming master alloy and a grain boundary phase-forming master alloy both in powder form and sintering the compact. The primary phase-forming master alloy has columnar crystal grains of R.sub.2 T.sub.14 B with a mean grain size of 3-50 .mu.m and grain boundaries of an R rich phase and contains 26-32 wt % of R. The grain boundary phase-forming master alloy is a crystalline alloy consisting essentially of 32-60 wt % of R and the balance of Co or Co and Fe. In anther form, a permanent magnet which contains R, T and B as main ingredients wherein R is yttrium or a rare earth element, T is Fe or Fe+Co/Ni and has a primary phase of R.sub.2 T.sub.14 B is produced by compacting a mixture of a primary phase-forming master alloy and a grain boundary-forming master alloy both in powder form and sintering the compact. The primary phase-forming master alloy has a primary phase of R.sub.2 T.sub.14 B and grain boundaries of an R rich phase. The grain boundary-forming master alloy contains 40-65 wt % of R, 30-60 wt % of Fe, Co or Ni and 1-12 wt % of Sn, In or Ga.

Preparation of permanent magnet

Growing community of inventors

Tokyo, Japan

Shinya Fujito