Production method of rare earth magnet

Patent metadata

Field	Value
Publication number	US-9520230-B2
Application number	US-201113824572-A
Country	US
Kind code	B2
Filing date	May 13, 2011
Priority date	Oct 25, 2010
Publication date	Dec 13, 2016
Grant date	Dec 13, 2016

Abstract

A rare earth magnet, which is represented by a neodymium magnet (Nd 2 Fe 14 B) and neodymium magnet films with applications in micro-systems. A method for producing a rare earth magnet, comprising: (a) quenching a molten metal having a rare earth magnet composition to form quenched flakes of nanocrystalline structure; sintering the quenched flakes; subjecting the sintered body obtained to an orientation treatment; and applying a heat treatment with pressurization at a temperature sufficiently high to enable diffusion or fluidization of a grain boundary phase and at the same time, low enough to prevent coarsening of the crystal grains, (b) thick films deposited on a substrate, applying an annealing to crystallize with pressurization at a temperature sufficiently high to enable diffusion or fluidization of a grain boundary phase and, at the same time, low enough to prevent coarsening of the crystal grains.

First claim

The invention claimed is:

1. The method for producing a rare earth magnet, comprising:
quenching a molten metal having a rare earth magnet composition to form quenched flakes having nanocrystalline structure,
sintering said quenched flakes,
subjecting the sintered body obtained to an orientation treatment, and then
applying a heat treatment with pressurization to the orientation-treated sintered body at a temperature sufficiently high to enable diffusion or fluidization of a grain boundary phase and, at the same time, low enough to prevent coarsening of the crystal grains;
wherein rare earth magnet being in the form of a bulk.

2. The method for producing a rare earth magnet according to claim 1 , wherein the pressure applied during said heat treatment is 1 to 300 MPa.

3. The method for producing a rare earth magnet according to claim 1 , wherein the heat treatment is performed for 1 minute to 5 hours.

4. The method for producing a rare earth magnet according to claim 1 , wherein the temperature of said heat treatment is a temperature that is higher than the melting point or eutectic temperature of the grain boundary phase and, at the same time, gives a crystal grain size of 300 nm or less after the heat treatment.

5. The method for producing a rare earth magnet according to claim 1 , wherein the temperature of said heat treatment is 450 to 700° C.

6. The method for producing a rare earth magnet according to claim 1 , wherein an element capable of lowering the temperature at which said grain boundary phase can be diffused or fluidized is added to said rare earth magnet composition.

7. The method for producing a rare earth magnet according to claim 6 , wherein said element is an element capable of lowering the melting point or eutectic temperature of the grain boundary phase down to a melting temperature lower than that of Nd.

8. The method for producing a rare earth magnet according to claim 7 , wherein said element is selected from Al, Cu, Mg, Fe, Co, Ag, Ni and Zn.

9. The method for producing a rare earth magnet according to claim 1 , wherein said rare earth magnet composition is represented by the following compositional formula; and an element capable of alloying with Fe, and thereby lowering the temperature at which the grain boundary phase can be diffused or fluidized, is added to said rare earth magnet composition in an amount sufficiently large to lower said temperature and small enough to cause no deterioration of magnetic characteristics and hot workability:
R 1 v Fe w Co x B y M 1 z
R 1 : one or more kinds of rare earth elements including Y,
M 1 : at least one of Ga, Zn, Si, Al, Nb, Zr, Ni, Cu, Cr, Hf, Mo, P, C, Mg and V,
13≦v≦20,
w=100−v−x−y−z,
0≦x≦30,
4≦y≦20,
0≦z≦3.

10. The method for producing a rare earth magnet according to claim 9 , wherein, in said compositional formula R 1 v Fe w Co x B y M 1 z , the amount v of R 1 (one or more kinds of rare earth elements including Y) is 13≦v≦17, and the amount y of B is 5≦y≦16.

11. The method for producing a rare earth magnet according to claim 9 , wherein the main phase of the rare earth magnet is Nd 2 Fe 14 B, and an element capable of alloying with Nd of the grain boundary phase and thereby lowering the temperature at which the grain boundary phase can be diffused or fluidized, is added in an amount sufficiently large to lower said temperature and small enough to cause no deterioration of magnetic characteristics and hot workability.

12. The method for producing a rare earth magnet according to claim 1 , wherein said rare earth magnet composition is represented by the following compositional formula, and composed of a main phase ((R 2 R 3 ) 2 (FeCo) 14 B) and grain boundary phases ((R 2 R 3 )(FeCo) 4 B 4 phase and R 2 R 3 phase); and an element capable of alloying with R and thereby lowering the temperature at which the grain boundary phase can be diffused or fluidized, is added to said rare earth magnet composition in an amount sufficiently large to lower said temperature and small enough to cause no deterioration of magnetic characteristics and hot workability:
R 2 a R 3 b Fe c Co d B e M 2 f
R 2 : one or more kinds of rare earth elements, excluding Dy and Tb and including Y,
R 3 : one or more kinds of heavy rare earth elements consisting of Dy and Tb,
M 2 : at least one of Ga, Zn, Si, Al, Nb, Zr, Ni, Cu, Cr, Hf, Mo, P, C, Mg, Hg, Ag and Au,
13≦a≦20,
0≦b≦4,
c=100−a−b−d−e−f,
0≦d≦30,
4≦e≦20,
0≦f≦3.

13. The method for producing a rare earth magnet according to claim 1 , wherein said orientation treatment is a hot working.

14. The method for producing a rare earth magnet according to claim 1 , wherein Ga is added to said rare earth magnet composition.

Assignees

• Sakuma Noritsugu
• Kishimoto Hidefumi
• Kato Akira
• Shoji Tetsuya
• Givord Dominique
• Dempsey Nora
• Woodcock Thomas George
• Gutfleisch Oliver
• Hrkac Gino
• Schrefl Thomas
• Toyota Motor Co Ltd
• Centre Nat Rech Scient
• Leibniz Inst For Solid State And Mat Res Dresden
• Univ Sheffield

Inventors

• Sakuma Noritsugu
• Kishimoto Hidefumi
• Kato Akira
• Shoji Tetsuya
• Givord Dominique
• Dempsey Nora
• Woodcock Thomas George
• Gutfleisch Oliver
• Hrkac Gino
• Schrefl Thomas

Classifications

• H01F41/005

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

• H01F10/126

  containing rare earth metals (H01F10/133 takes precedence) · CPC title

• B22F2998/00

  Supplementary information concerning processes or compositions relating to powder metallurgy · CPC title

• C22C38/06

  containing aluminium · CPC title

• B22F3/24

  After-treatment of workpieces or articles {(B22F3/1146 takes precedence)} · CPC title