Radiopaque intraluminal stents comprising cobalt-based alloys with primarily single-phase supersaturated tungsten content

Patent metadata

Field	Value
Publication number	US-11298251-B2
Application number	US-201916601259-A
Country	US
Kind code	B2
Filing date	Oct 14, 2019
Priority date	Nov 17, 2010
Publication date	Apr 12, 2022
Grant date	Apr 12, 2022

Abstract

Embodiments are directed to radiopaque implantable structures (e.g., stents) formed of cobalt-based alloys that comprise cobalt, chromium, tungsten, and nickel. Tungsten is present above its solubility limit (about 15%), but is still only present as a super-saturated, primarily single-phase material exhibiting an FCC microcrystalline structure.

First claim

The invention claimed is:

1. A radiopaque stent, comprising:
a cylindrical main body comprising a cobalt-chromium alloy including cobalt and chromium, the cobalt-chromium alloy including tungsten as a radiopacity increasing element, the tungsten comprising about 20% to about 35% by weight of the cobalt-chromium alloy, the tungsten content being super-saturated, above the solubility limit of tungsten in the cobalt-chromium alloy;
wherein the cobalt-chromium alloy further comprises nickel, the nickel being present in a concentration of 5% to about 15% by weight; and
wherein the cobalt-chromium alloy exhibits a primarily single-phase FCC solid solution, wherein a second phase of the tungsten is present and makes up no more than 10% volume fraction in the cobalt-chromium alloy, the second phase having an average particle size of less than 5 μm, even with the super-saturated tungsten content.

2. The radiopaque stent of claim 1 , wherein the cobalt-chromium alloy comprises cobalt in an amount from about 30% to about 50% by weight of the cobalt-chromium alloy.

3. The radiopaque stent of claim 1 , wherein the cobalt-chromium alloy comprises chromium in an amount of about 20% by weight of the cobalt-chromium alloy.

4. The radiopaque stent of claim 1 , wherein the cobalt-chromium alloy comprises nickel in an amount of about 10% by weight of the cobalt-chromium alloy.

5. The radiopaque stent of claim 1 , wherein the cobalt-chromium alloy is entirely free of molybdenum.

6. The radiopaque stent of claim 1 , wherein the cobalt-chromium alloy comprises no more than 1% of silicon, phosphorus, and/or sulfur by weight.

7. The radiopaque stent of claim 1 , wherein the cobalt-chromium alloy further comprises manganese in a concentration of up to 5% by weight of the cobalt-chromium alloy.

8. The radiopaque stent of claim 1 , wherein the cobalt-chromium alloy further comprises iron in a concentration of up to 5% by weight of the cobalt-chromium alloy.

9. The radiopaque stent of claim 1 , wherein the cobalt-chromium alloy further comprises both manganese and iron in a concentration of about 1.5% each, by weight.

10. The radiopaque stent of claim 1 , wherein cobalt comprises from about 66 to 68% by weight of the cobalt-chromium alloy.

11. The radiopaque stent of claim 1 , wherein a weight percent ratio of tungsten to cobalt is at least 0.4.

12. The radiopaque stent of claim 1 , wherein a ratio of tungsten to cobalt is from 0.4 to 1.2.

13. The radiopaque stent of claim 1 , wherein a ratio of tungsten to cobalt is from 0.40 to 0.45.

14. The radiopaque stent of claim 1 , wherein a ratio of tungsten to cobalt is from 0.57 to 0.63.

15. The radiopaque stent of claim 1 , wherein a ratio of tungsten to cobalt is from 1.07 to 1.13.

16. The radiopaque stent of claim 1 , wherein the cobalt-chromium alloy is substantially free of carbon.

17. A radiopaque stent, comprising:
a cylindrical main body formed from a single homogenous cobalt-chromium alloy including cobalt, chromium, nickel, and tungsten, the cobalt-chromium alloy not including any other alloying elements in amounts greater than 3% by weight;
the cobalt-chromium alloy including tungsten as a radiopacity increasing element, the tungsten comprising about 20% to about 35% by weight of the cobalt-chromium alloy, the tungsten content being super-saturated, above the solubility limit of tungsten in the cobalt-chromium alloy at ambient temperature;
wherein the cobalt-chromium alloy comprises about 10% by weight nickel; and
wherein the cobalt-chromium alloy exhibits a primarily single-phase FCC solid solution structure, a second phase of the tungsten is present in the cobalt-chromium alloy having a maximum particle size of less than 15 μm, even with the super-saturated tungsten content.

18. The radiopaque stent of claim 17 , wherein the cobalt-chromium alloy is entirely free of molybdenum.

19. The radiopaque stent of claim 17 , wherein the cobalt-chromium alloy is substantially free of carbon.

20. The radiopaque stent of claim 17 , wherein the cobalt-chromium alloy is entirely free of carbon.

21. A radiopaque stent, comprising:
a cylindrical main body comprising a cobalt-chromium alloy including cobalt and chromium, the cobalt-chromium alloy including tungsten as a radiopacity increasing element, the tungsten comprising about 20% to about 35% by weight of the cobalt-chromium alloy, the tungsten content being super-saturated, above the solubility limit of tungsten in the cobalt-chromium alloy;
wherein the cobalt-chromium alloy further comprises nickel, the nickel being present in a concentration of 5% to about 15% by weight;
wherein the cobalt-chromium alloy exhibits a primarily single-phase FCC solid solution, wherein no more than 10% volume fraction of a second phase of the tungsten is present in the cobalt-chromium alloy, the second phase having an average particle size of less than 5 μm, even with the super-saturated tungsten content; and
at least one of (i) or (ii):
(i) wherein a ratio of tungsten to cobalt is from 1.07 to 1.13;
(ii) wherein the cobalt-chromium alloy further comprises both manganese and iron in a concentration of about 1.5% each, by weight.

22. The radiopaque stent of claim 1 , wherein the tungsten comprises 25% to about 30% by weight of the cobalt-chromium alloy.

Assignees

• Abbott Cardiovascular Systems Inc

Inventors

• Simpson John A
• Gill Puneet Kamal Singh
• Kramer-Brown Pamela A

Classifications

• C22C19/07 Primary

  based on cobalt · CPC title

• C22C27/04

  Alloys based on tungsten or molybdenum · CPC title

• A61L31/022

  Metals or alloys · CPC title

• A61L31/18

  Materials at least partially X-ray or laser opaque · CPC title

• C22C27/06

  Alloys based on chromium · CPC title