Processing of nickel-titanium alloys

Patent metadata

Field	Value
Publication number	US-9440286-B2
Application number	US-201313908304-A
Country	US
Kind code	B2
Filing date	Jun 3, 2013
Priority date	Aug 12, 2010
Publication date	Sep 13, 2016
Grant date	Sep 13, 2016

Abstract

Processes for producing a nickel-titanium alloy are disclosed. The processes are characterized by the production of nickel-titanium alloy articles having improved microstructure. A pre-alloyed nickel-titanium alloy is melted and atomized to form molten nickel-titanium alloy particles. The molten nickel-titanium alloy particles are cooled to form nickel-titanium alloy powder. The nickel-titanium alloy powder is consolidated to form a fully-densified nickel-titanium alloy preform that is hot worked to form a nickel-titanium alloy article. Any second phases present in the nickel-titanium alloy article have a mean size of less than 10 micrometers measured according to ASTM E1245-03 (2008) or an equivalent method.

First claim

What is claimed is:

1. A nickel-titanium alloy article comprising:
50.0 to 60.0 weight percent nickel based on the total weight of the article; and
balance titanium and residual elements;
wherein the residual elements comprise greater than 300 ppm oxygen; and
wherein oxide inclusions and carbide inclusions present in the nickel-titanium alloy article have a mean size of less than 7.5 micrometers measured according to ASTM E1245-03 (2008) or an equivalent method.

2. The nickel-titanium alloy article of claim 1 , wherein the residual elements comprise greater than 350 ppm oxygen.

3. The nickel-titanium alloy article of claim 1 , wherein the residual elements comprise greater than 100 ppm carbon.

4. The nickel-titanium alloy article of claim 1 , wherein oxide inclusions and carbide inclusions present in the nickel-titanium alloy article have a mean size of less than 3 micrometers measured according to ASTM E1245-03 (2008) or an equivalent method.

5. The nickel-titanium alloy article of claim 1 , wherein oxide inclusions and carbide inclusions present in the nickel-titanium alloy article have a mean size of less than 5 micrometers measured according to ASTM E1245-03 (2008) or an equivalent method.

6. The nickel-titanium alloy article of claim 1 , wherein oxide inclusions and carbide inclusions present in the nickel-titanium alloy article have a mean size of less than 2.5 micrometers measured according to ASTM E1245-03 (2008) or an equivalent method.

7. The nickel-titanium alloy article of claim 1 , wherein oxide inclusions and carbide inclusions present in the nickel-titanium alloy article have a mean size of less than 1.5 micrometers measured according to ASTM E1245-03 (2008) or an equivalent method.

8. The nickel-titanium alloy article of claim 1 , wherein second phases present in the nickel-titanium alloy article have an area fraction of less than 2.5 percent measured according to ASTM E1245-03 (2008) or an equivalent method.

9. The nickel-titanium alloy article of claim 1 , wherein second phases present in the nickel-titanium alloy article have an area fraction of less than 2.0 percent measured according to ASTM E1245-03 (2008) or an equivalent method.

10. The nickel-titanium alloy article of claim 1 , wherein second phases present in the nickel-titanium alloy article have an area fraction of less than 1.5 percent measured according to ASTM E1245-03 (2008) or an equivalent method.

11. The nickel-titanium alloy article of claim 1 , wherein oxide inclusions and carbide inclusions present in the nickel-titanium alloy article have a mean size of less than 2.5 micrometers, and an area fraction of less than 2.5 percent, measured according to ASTM E1245-03 (2008) or an equivalent method.

12. The nickel-titanium alloy article of claim 1 , wherein oxide inclusions and carbide inclusions present in the nickel-titanium alloy article have a mean size of less than 2 micrometers, and an area fraction of less than 2.0 percent, measured according to ASTM E1245-03 (2008) or an equivalent method.

13. The nickel-titanium alloy article of claim 1 , wherein the article is selected from the group consisting of a billet, bar, rod, tube, slab, plate, sheet, foil, or wire.

14. The nickel-titanium alloy article of claim 1 , wherein the alloy comprises 54.5 weight percent to 57.0 weight percent nickel.

15. The nickel-titanium alloy article of claim 1 , wherein the alloy comprises 49.0 atomic percent to 55.0 atomic percent nickel.

16. The nickel-titanium alloy article of claim 1 , wherein the alloy further comprises at least one additional alloying element selected from the group consisting of iron, niobium, and hafnium.

17. The nickel-titanium alloy article of claim 1 , wherein non-metallic Ti 4 Ni 2 O x oxide second phases present in the nickel-titanium alloy article have a mean size of less than 7.5 micrometers, and an area fraction of less than 2.5 percent, measured according to ASTM E1245-03 (2008) or an equivalent method.

18. The nickel-titanium alloy article of claim 1 , wherein non-metallic Ti 4 Ni 2 O x oxide second phases present in the nickel-titanium alloy article have a mean size of less than 2.5 micrometers, and an area fraction of less than 2.5 percent, measured according to ASTM E1245-03 (2008) or an equivalent method.

19. A process for producing the nickel-titanium alloy article of claim 1 , the process comprising:
melting a pre-alloyed nickel-titanium alloy;
atomizing the molten nickel-titanium alloy to form molten nickel-titanium alloy particles;
cooling the molten nickel-titanium alloy particles to form a nickel-titanium alloy powder;
hot isostatic pressing at least a portion of the nickel-titanium alloy powder to form a fully-densified nickel-titanium alloy preform;
hot working the nickel-titanium alloy preform; and
cold working the nickel-titanium alloy after the hot working to form a nickel-titanium alloy article.

20. The process of claim 19 , wherein the hot working is performed on the nickel-titanium alloy preform at an initial temperature in the range of 600° C. to 900° C.

21. The process of claim 19 , further comprising annealing the nickel-titanium alloy article after the cold working.

22. The process of claim 21 , wherein the annealing is performed at a temperature in the range of 600° C. to 900° C.

23. The process of claim 19 , wherein the nickel-titanium alloy comprises 50.0 to 60.0 weight percent nickel based on the total weight of the alloy, and balance titanium and residual elements.

24. The process of claim 19 , wherein the nickel-titanium alloy comprises 49.0 atomic percent to 55.0 atomic percent nickel, and balance titanium and residual elements.

25. The process of claim 19 , wherein the nickel-titanium alloy further comprises at least one additional alloying element selected from the group consisting of iron, niobium, and hafnium.

26. A nickel-titanium alloy article comprising:
50.0 to 60.0 weight percent nickel based on the total weight of the article; and
balance titanium and residual elements;
wherein the residual elements comprise greater than 300 ppm oxygen; and
wherein oxide inclusions and carbide inclusions present in the nickel-titanium alloy article have a mean size of less than 2.5 micrometers measured according to ASTM E1245-03 (2008) or an equivalent method,
wherein oxide inclusions and carbide inclusions present in the nickel-titanium alloy article have an area fraction of less than 2.5 percent measured according to ASTM E1245-03 (2008) or an equivalent method, and
wherein the article is selected from the group consisting of a billet, bar, rod, or wire.

27. The nickel-titanium alloy article of claim 26 , wherein the alloy comprises 49.0 atomic percent to 55.0 atomic percent nickel.

28. The nickel-titanium alloy article of claim 26 , wherein the alloy further comprises at least one additional alloying element selected from the group consisting of iron, niobium, and hafnium.

Assignees

• Wojcik C Craig
• Ati Properties Llc

Inventors

• Wojcik C Craig

Classifications

• B22F1/052

  characterised by a mixture of particles of different sizes or by the particle size distribution · CPC title

• B22F1/0014

  Operations & Transport · mapped topic

• C22C19/03

  based on nickel · CPC title

• C21D2201/01

  Shape memory effect · CPC title

• B22F2998/10

  Processes characterised by the sequence of their steps · CPC title