Fe-based sintered body, Fe-based sintered body production method, and hot-pressing die

Patent metadata

Field	Value
Publication number	US-11858045-B2
Application number	US-201917266375-A
Country	US
Kind code	B2
Filing date	Jul 24, 2019
Priority date	Aug 7, 2018
Publication date	Jan 2, 2024
Grant date	Jan 2, 2024

Abstract

Provided is a Fe-based sintered body which has both of a high hardness and a high thermal conductivity and which can be more stably produced. The Fe-based sintered body includes: a matrix ( 1 ) containing Fe as a main component; and a hard phase ( 4 ) dispersed in the matrix ( 1 ). The matrix ( 1 ) is formed in a network shape and contains αFe. The hard phase ( 4 ) contains TiC.

First claim

The invention claimed is:

1. A Fe-based sintered body comprising:
a matrix containing Fe as a main component; and
a dispersed phase in the matrix,
the matrix being formed in a network shape and containing αFe,
the dispersed phase including a hard phase containing TiC, the hard phase having a ring shape or a ring-like shape, and
the hard phase having a width of not more than 1.0 μm in a direction perpendicular to a circumferential direction of the hard phase,

wherein the matrix accounts for not less than 60% by mass in the Fe-based sintered body, and the matrix has a cementite content of not more than 5% by mass, and wherein the Fe-based sintered body has a surface portion which is exposed to outside and an inside portion which is present closer to a center as compared to the surface portion, and the surface portion has a higher hardness than the inner portion.

2. The Fe-based sintered body as set forth in claim 1 , having a hardness of not less than 50 HRC and a thermal conductivity of not less than 40 W/(m·K).

3. The Fe-based sintered body as set forth in claim 1 , wherein the matrix has an αFe content of not less than 70% by mass.

4. The Fe-based sintered body as set forth in claim 1 , wherein the matrix has a Cu content of not more than 0.1% by mass and an Si content of not more than 0.1% by mass.

5. The Fe-based sintered body as set forth in claim 1 , wherein the dispersed phase further includes a first sub-phase containing TiB 2 , and a second sub-phase containing Fe 2 B.

6. The Fe-based sintered body as set forth in claim 5 , wherein
the first sub-phase accounts for not less than 10% by mass in the Fe-based sintered body and has a higher hardness than the matrix, and
the second sub-phase has a higher hardness than the matrix.

7. The method of producing a Fe-based sintered body as set forth in claim 1 , the method comprising the step of sintering a compact formed by pressure-molding of a mixed powder containing Fe powder and TiB 2 powder, the compact being sintered by (i) applying pressure with use of a pressure member made of graphite and (ii) heating at the same time,
in the step of sintering, the compact being sintered such that:
by (i) applying a pressure of not less than 15 MPa and (ii) heating at a temperature of not less than 1323 K, (a) at least part of the TiB 2 is decomposed and (b) a network-like matrix is formed, the network-like matrix containing Fe as a main component and also containing Ti;
the matrix contains αFe; and
TiC dispersed in the matrix is generated by a reaction between Ti and C, the Ti being derived from the TiB 2 , and the C being derived from the pressure member.

8. The method as set forth in claim 7 , wherein in the step of sintering, the compact is sintered by an electric discharge sintering method.

9. A hot press die produced by using a Fe-based sintered body as recited in claim 1 .

10. A Fe-based sintered body comprising:
a matrix containing Fe as a main component; and
a dispersed phase in the matrix,
the matrix being formed in a network shape and containing αFe, and
the dispersed phase including a hard phase, the hard phase containing TiC and having a width of not more than 1.0 μm in a direction perpendicular to a longitudinal direction of the hard phase,

wherein the matrix accounts for not less than 60% by mass in the Fe-based sintered body, and the matrix has a cementite content of not more than 5% by mass, and wherein the Fe-based sintered body has a surface portion which is exposed to outside and an inside portion which is present closer to a center as compared to the surface portion, and the surface portion has a higher hardness than the inner portion.

11. The Fe-based sintered body as set forth in claim 10 , having a hardness of not less than 50 HRC and a thermal conductivity of not less than 40 W/(m·K).

12. The Fe-based sintered body as set forth in claim 10 , wherein the matrix has an αFe content of not less than 70% by mass.

13. The Fe-based sintered body as set forth in claim 10 , wherein the matrix has a Cu content of not more than 0.1% by mass and an Si content of not more than 0.1% by mass.

14. The Fe-based sintered body as set forth in claim 10 , wherein the dispersed phase further includes a first sub-phase containing TiB2, and a second sub-phase containing Fe2B.

15. The Fe-based sintered body as set forth in claim 14 , wherein
the first sub-phase accounts for not less than 10% by mass in the Fe-based sintered body and has a higher hardness than the matrix, and
the second sub-phase has a higher hardness than the matrix.

Assignees

• Univ Hiroshima
• Y Tec Corp
• Keylex Corp
• Mazda Motor

Inventors

• Matsugi Kazuhiro
• Ke Yujiao
• Xu Zhefeng
• Sugio Kenjiro
• Choi Yongbum
• Sasaki Gen
• Suetsugu Hajime
• Kondo Hiroki
• Manabe Hideki
• Yamane Kyotaro
• Hatakeyama Kenichi
• Kawasaki Keizo
• Itaoka Tsuyoshi
• Seno Shinsaku
• Tamura Yasushi
• Ino Ichirou
• Hirao Yoshihide

Classifications

• B22F3/105 Primary

  by using electric current {other than for infrared radiant energy}, laser radiation or plasma (B22F3/11 takes precedence){; by ultrasonic bonding (B22F3/115 takes precedence)} · CPC title

• B22F3/004

  Filling molds with powder (feeding material to presses in general B30B15/302) · CPC title

• B22F3/14

  simultaneously · CPC title

• B22F9/04

  starting from solid material, e.g. by crushing, grinding or milling ({C22C1/1084 takes precedence}; crushing, grinding or milling, in general, see the relevant subclasses, e.g. B02C) · CPC title

• C22C33/0292 Primary

  with more than 5% preformed carbides, nitrides or borides · CPC title