Heat-resistant alloy and method of manufacturing the same

Patent metadata

Field	Value
Publication number	US-9970082-B2
Application number	US-201214365764-A
Country	US
Kind code	B2
Filing date	Dec 13, 2012
Priority date	Dec 16, 2011
Publication date	May 15, 2018
Grant date	May 15, 2018

Abstract

A heat-resistant alloy that satisfies physical properties such as proof stress and hardness adapted to an increase in the melting point of a welding object compared to conventional alloys is provided. The heat resistant alloy includes a first phase, as a main component, containing a Mo or W metal phase, a second phase containing a Mo—Si—B—based alloy, and a third phase containing titanium carbonitride, wherein the balance is inevitable compounds and inevitable impurities.

First claim

The invention claimed is:

1. A heat-resistant alloy comprising:
a first phase comprising a Mo or W metal phase,
a second phase comprising a Mo—Si—B-based alloy, and
a third phase comprising a titanium carbonitride phase,
wherein the balance is an inevitable compound and an inevitable impurity,
wherein a composition of the titanium carbonitride is expressed by TiC x N 1−x (x=0.3 to 0. 7),
wherein titanium carbonitride grains in the alloy have an average grain size of 0.5 μm or more and 11 μm or less, and
wherein a ratio of the number of titanium carbonitride grains with grain sizes of 0.5 to 2.5 μm in the alloy is 20 to 40% of all titanium carbonitride grains in the alloy and a ratio of the number of titanium carbonitride grains with grain sizes of 4.0 to 6.0 μm in the alloy is 10 to 30% of all the titanium carbonitride grains in the alloy, and
wherein the distribution of titanium carbonitride grains in the alloy has two peak values, a peak value between 0.5 and 2.5 μm and a peak value between 4.0 and 6.0 μm.

2. The heat-resistant alloy according to claim 1 , wherein the Mo—Si—B-based alloy is composed mainly of Mo 5 SiB 2.

3. The heat-resistant alloy according to claim 1 , wherein the first phase is the Mo metal phase and the content of the titanium carbonitride is 1 mass % or more and 80mass % or less.

4. The heat-resistant alloy according to claim 1 , wherein the first phase is the Mo metal phase and the content of the titanium carbonitride is 3 mass % or more and 25 mass % or less.

5. The heat-resistant alloy according to claim 1 , wherein the first phase is the W metal phase and the content of the titanium carbonitride is 0.5 mass % or more and 75 mass % or less.

6. The heat-resistant alloy according to claim 1 , wherein the first phase is the W metal phase and the content of the titanium carbonitride is 5 mass % or more and 16 mass % or less.

7. The heat-resistant alloy according to claim 1 , wherein the first phase is the Mo metal phase and the content of the Mo—Si—B-based alloy is 5 mass % or more and 80 mass % or less.

8. The heat-resistant alloy according to claim 1 , wherein the first phase is the Mo metal phase and the content of the Mo—Si—B-based alloy is 10 mass % or more and 60 mass % or less.

9. The heat-resistant alloy according to claim 1 , wherein the first phase is the W metal phase and the content of the Mo—Si—B-based alloy is 5 mass % or more and 75 mass % or less.

10. The heat-resistant alloy according to claim 1 , wherein the first phase is the W metal phase and the content of the Mo—Si—B-based alloy is 10 mass % or more and 30 mass % or less.

11. The heat-resistant alloy according to claim 1 , wherein titanium carbonitride grains in the alloy have an average grain size of 0.5 μm or more and 7 μm or less.

12. The heat-resistant alloy according to claim 1 , wherein titanium carbonitride grains in the alloy have an average grain size of 0.5 μm or more and 5 μm or less.

13. The heat-resistant alloy according to claim 1 , wherein the Mo—Si—B-based alloy in the alloy has an average grain size of 0.5 μm or more and 20 μm or less.

14. The heat-resistant alloy according to claim 1 , having a Vickers hardness of 500 Hv or more at 20° C. and a 0.2% proof stress of 500 MPa or more at 1200° C.

15. The heat-resistant alloy according to claim 1 , having a Vickers hardness of 900 Hv or more at 20° C. and a bending strength of 600 MPa or more at 1200° C.

16. A friction stir welding tool using the heat-resistant alloy according to claim 1 .

17. A friction stir welding tool having, on a surface of the friction stir welding tool according to claim 16 , a coating layer made of at least one or more kinds of elements selected from the group consisting of Group IVa elements, Group Va elements, Group VIa elements, Group IIIb elements, and Group IVb elements other than C of the Periodic Table or a carbide, a nitride, or a carbonitride of at least one or more kinds of elements selected from the element group.

18. A friction stir apparatus comprising the friction stir welding tool according to claim 16 .

19. A method of manufacturing the heat-resistant alloy according to claim 1 , comprising:
mixing together a Mo powder, a Mo—Si—B-based compound powder, and a titanium carbonitride powder;
compression-molding at room temperature a mixed powder obtained by the mixing;
heating a compact, obtained by the molding step, at 1600° C. or more and 1820° C. or less in a reduced-pressure atmosphere containing at least nitrogen, thereby sintering the compact; and
hot-isostatic-pressing in an inert atmosphere a sintered body obtained by sintering.

20. A method of manufacturing the heat-resistant alloy according to claim 1 , comprising:
mixing together a Mo powder, a Mo—Si—B-based alloy powder, and a titanium carbonitride powder;
compression-molding at room temperature a mixed powder obtained by the mixing; and
hot-isostatic-pressing in an inert atmosphere a compact obtained by the molding thereby pressure sintering the compact.

21. A method of manufacturing the heat-resistant alloy according to claim 1 , comprising:
mixing together a Mo powder, a Mo—Si—B-based alloy powder, and a TiCN5 powder; and
sintering, while pressing a mixed powder, obtained by the mixing, at 30 MPa or more and 70 MPa or less in a reduced-pressure atmosphere, an atmosphere containing at least hydrogen, or an inert atmosphere, heating the mixed powder at 1600° C. or more and 1900° C. or less.

22. A method of manufacturing the heat-resistant alloy according to claim 1 , comprising:
mixing together a W powder, a Mo—Si—B-based alloy powder, and a titanium carbonitride powder; and
sintering, while pressing a mixed powder, obtained by the mixing, at 30 MPa or more and 70 MPa or less in a reduced-pressure atmosphere, an atmosphere containing at least hydrogen, or an inert atmosphere, heating the mixed powder at 1700° C. or more and 2000° C. or less.

Assignees

• Almt Corp

Inventors

• Yamazaki Shigekazu
• Tsuji Ayuri
• Katoh Masahiro
• Ikegaya Akihiko

Classifications

• C22C29/14

  based on borides · CPC title

• C22C27/04 Primary

  Alloys based on tungsten or molybdenum · CPC title

• C22C32/0047

  with carbides, nitrides, borides or silicides as the main non-metallic constituents · CPC title

• B22F2005/002

  Tools other than cutting tools · CPC title

• B22F2998/10

  Processes characterised by the sequence of their steps · CPC title