Permanent magnet and method of producing permanent magnet

Patent metadata

Field	Value
Publication number	US-9281105-B2
Application number	US-201113808612-A
Country	US
Kind code	B2
Filing date	Jul 13, 2011
Priority date	Jul 14, 2010
Publication date	Mar 8, 2016
Grant date	Mar 8, 2016

Abstract

A permanent magnet has a grain structure that includes a main phase and a grain boundary phase that is primarily composed of a first metal. A second metal that enhances the coercivity of the permanent magnet and a third metal that has a lower standard free energy of oxide formation than the first metal and the second metal are diffused in the permanent magnet, and the third metal is present in the form of an oxide in the grain boundary phase.

First claim

The invention claimed is:

1. A permanent magnet that has a grain structure that comprises a main phase and a grain boundary phase which is primarily composed of a first metal,
the permanent magnet wherein
a second metal that enhances the coercivity of the permanent magnet and a third metal that has a lower standard free energy of oxide formation than the first metal and the second metal are diffused in the permanent magnet, and
the third metal is present in the form of an oxide in the grain boundary phase;
wherein the second metal does not form an oxide;
wherein the third metal is substantially not present in the main phase; and
wherein the third metal oxide is present at triple points where three regions of the grain boundary phases meet.

2. The permanent magnet according to claim 1 , wherein the first metal is neodymium or praseodymium.

3. The permanent magnet according to claim 2 , wherein the second metal is any one of dysprosium, terbium or holmium, and the third metal is either yttrium or scandium.

4. A permanent magnet that has a grain structure that comprises a main phase and a grain boundary phase which is primarily composed of a first metal,
the permanent magnet comprising:
a second metal that enhances the coercivity of the permanent magnet; and
a third metal that has a lower standard free energy of oxide formation than the first metal and the second metal, wherein:
both densities of the second metal and the third metal are richer in the grain boundary phase than in the main phase; and
the third metal is present in the form of an oxide in the grain boundary phase;
wherein the second metal does not form an oxide;
wherein the third metal is substantially not present in the main phase; and
wherein the third metal oxide is present at triple points where three regions of the grain boundary phases meet.

5. A permanent magnet that has a grain structure composed of a main phase and a grain boundary phase, comprising:
a first metal as a primary metal that composes the main phase;
a second metal that is diffused in the permanent magnet and enhances coercivity of the permanent magnet; and
a third metal, which is diffused in the permanent magnet and has a lower standard free energy of oxide formation than the first metal and the second metal,
wherein
the third metal is present in the form of an oxide in the grain boundary phase;
wherein the second metal does not form an oxide;
wherein the third metal is substantially not present in the main phase; and
wherein the third metal oxide is present at triple points where three regions of the grain boundary phases meet.

Assignees

• Miyamoto Noritaka
• Omura Shinya
• Toyota Motor Co Ltd

Inventors

• Miyamoto Noritaka
• Omura Shinya

Classifications

• H01F1/0577 Primary

  sintered · CPC title

• H01F41/0293

  diffusion of rare earth elements, e.g. Tb, Dy or Ho, into permanent magnets · CPC title

• H01F1/01 Primary

  of inorganic materials (H01F1/44 takes precedence) · CPC title

• H01F41/005

  Impregnating or encapsulating (insulating of windings H01F41/12) · CPC title

• C23C14/34

  Sputtering · CPC title