Rare earth sintered magnet and making method

Patent metadata

Field	Value
Publication number	US-10074477-B2
Application number	US-201615375655-A
Country	US
Kind code	B2
Filing date	Dec 12, 2016
Priority date	Apr 11, 2012
Publication date	Sep 11, 2018
Grant date	Sep 11, 2018

Abstract

A rare earth sintered magnet is an anisotropic sintered body comprising Nd 2 Fe 14 B crystal phase as primary phase and having the composition R 1 a T b M c Si d B e wherein R 1 is a rare earth element inclusive of Sc and Y, T is Fe and/or Co, M is Al, Cu, Zn, In, P, S, Ti, V, Cr, Mn, Ni, Ga, Ge, Zr, Nb, Mo, Pd, Ag, Cd, Sn, Sb, Hf, Ta, or W, “a” to “e” are 12≤a≤17, 0≤c≤10, 0.3≤d≤7, 5≤e≤10, and the balance of b, wherein Dy and/or Tb is diffused into the sintered body from its surface.

First claim

The invention claimed is:

1. A method for preparing a rare earth sintered magnet, comprising the steps of:
providing an anisotropic sintered body comprising Nd 2 Fe 14 B crystal phase as primary phase and having the composition R 1 a T b M c Al f Si d B e wherein R 1 is at least one element selected from rare earth elements inclusive of Sc and Y, T is one or both of Fe and Co, M is at least one element selected from the group consisting of Cu, Zn, In, P, S, Ti, V, Cr, Mn, Ni, Ga, Ge, Zr, Nb, Mo, Pd, Ag, Cd, Sn, Sb, Hf, Ta, and W, Al is aluminum, Si is silicon, B is boron, “a” to “f” indicative of atomic percent in the alloy are in the range: 12≤a≤17, 0≤c≤5, 0.3≤f≤10, 0.3 ≤d≤7, 5≤e≤10, and the balance of b, and
diffusing element R 2 into the sintered body from its surface at a temperature lower than or equal to the sintering temperature of the sintered body, wherein R 2 is one or both of Dy and Tb.

2. The method of claim 1 wherein the diffusion temperature is 800 to 1,050° C.

3. The method of claim 2 wherein the diffusion temperature is 850 to 1,000° C.

4. The method of claim 1 , further comprising the step of effecting aging treatment after the step of causing element R 2 to diffuse into the sintered body.

5. The method of claim 4 wherein the aging treatment is at a temperature of 400 to 800° C.

6. The method of claim 5 wherein the aging treatment is at a temperature of 450 to 750° C.

7. The method of claim 1 wherein R 1 contains at least 80 at % of Nd and/or Pr.

8. The method of claim 1 wherein T contains at least 85 at % of Fe.

Assignees

• Shinetsu Chemical Co

Inventors

• Nagata Hiroaki
• Gouki Yuuji
• Sakaki Kazuaki
• Nomura Tadao
• Hirota Koichi
• Nakamura Hajime

Classifications

• C21D6/004

  containing Cr and Ni · CPC title

• H01F1/0577 Primary

  sintered · CPC title

• C22C33/02

  by powder metallurgy · CPC title

• C22C38/20

  with copper · CPC title

• C22C38/60

  containing lead, selenium, tellurium, or antimony, or more than 0.04% by weight of sulfur · CPC title