# US 12,735,774 B2 · Processing of cobalt-tungsten alloys > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 12,735,774 B2 - Document ID: US12735774B2 - Status: Granted - Kind: B2 - Application number: 18/324,749 - Filed: 2023-05-26 - Published: 2023-12-14 - Granted: 2026-09-15 - Earliest claimed: 2022-06-08 - Assignees: Abbott Cardiovascular Systems Inc. - Applicants: Abbott Cardiovascular Systems, Inc. - Inventors: Donal F. Manley; Puneet Kamal Singh Gill; Diarmuid P. Meagher - Web page: https://patentgrep.com/patent/US12735774B2 ## CPC - C22C 30/00: Alloys containing less than 50% by weight of each constituent - A61F 2/82: Devices providing patency to, or preventing collapsing of, tubular structures of the body, e.g. stents (stent-grafts for tubular structures of the body other than blood vessels A61F2/04; stent-grafts for blood vessels A61F2/07) - A61L 31/022: {Metals or alloys} - A61L 31/18: Materials at least partially X-ray or laser opaque - C22C 19/07: based on cobalt - A61F 2310/00035: Other metals or alloys - C22C: ALLOYS (treatment of alloys C21D, C22F) - A61F: FILTERS IMPLANTABLE INTO BLOOD VESSELS; PROSTHESES; DEVICES PROVIDING PATENCY TO, OR PREVENTING COLLAPSING OF, TUBULAR STRUCTURES OF THE BODY, e.g. STENTS; ORTHOPAEDIC, NURSING OR CONTRACEPTIVE DEVICES; FOMENTATION; TREATMENT OR PROTECTION OF EYES OR EARS; BANDAGES, DRESSINGS OR ABSORBENT PADS; FIRST-AID KITS (dental prosthetics A61C) - A61L: METHODS OR APPARATUS FOR STERILISING MATERIALS OR OBJECTS IN GENERAL; DISINFECTION, STERILISATION OR DEODORISATION OF AIR; CHEMICAL ASPECTS OF BANDAGES, DRESSINGS, ABSORBENT PADS OR SURGICAL ARTICLES; MATERIALS FOR BANDAGES, DRESSINGS, ABSORBENT PADS OR SURGICAL ARTICLES (preservation of bodies or disinfecting characterised by the agents employed A01N; preserving, e.g. sterilising, food or foodstuffs A23; preparations for medical, dental or toiletry purposes A61K) ## Abstract Radiopaque implantable structures (e.g., stents) formed of cobalt-based alloys that comprise cobalt, chromium, tungsten, nickel, and platinum or another another metal having an atomic number or density greater than that of cobalt for increased radiopacity. In particular, processes are described for removing precipitate inclusions (e.g., tungsten rich precipitates) that render the alloy otherwise unsuitable for use in formation of a stent or similar implantable structure. The alloy with such precipitate inclusions can be heat treated within a narrow temperature range of about 1250° C. (e.g., 1225° C. to 1275° C.) for a time period in a narrow range of about 30 minutes (e.g., 20 to 40 minutes), to remove such precipitate inclusions. Higher temperatures and/or longer treatment times surprisingly do not resolve the precipitate inclusions, but treatment at about 1250° C. for about 30 minutes substantially removes the precipitates, resulting in a substantially homogenous structure suitable for use as a stent. ## Claims ### Claim 1 A process comprising: providing an alloy formed from cobalt in an amount from about 20% to about 40% by weight, chromium, tungsten, and at least one of a platinum group metal, a precious metal, a refractory metal or another metal having an atomic number or density greater than that of cobalt; and heating the alloy to a temperature of at least 1200° C.; and quenching the alloy to 600° C. or less. ### Claim 2 (depends on 1) The process of claim 1, wherein the alloy comprises cobalt, chromium, tungsten, and platinum. ### Claim 3 (depends on 1) The process of claim 1, wherein the quenching is performed within a period of time of less than 5 minutes. ### Claim 4 (depends on 1) The process of claim 1, wherein the quenching is performed by immersing the alloy in water. ### Claim 5 (depends on 1) The process of claim 1, wherein heating the alloy is to a temperature of at least about 1250° C. for a time period of at least about 30 minutes. ### Claim 6 (depends on 1) The process of claim 1, wherein the alloy comprises chromium in an amount of about 20% by weight. ### Claim 7 (depends on 1) The process of claim 1, wherein the alloy comprises nickel in an amount of about 10% by weight. ### Claim 8 (depends on 1) The process of claim 1, wherein the alloy is substantially or entirely free of molybdenum and/or carbon. ### Claim 9 (depends on 1) The process of claim 1, wherein the quenching is performed within a period of time of less than 1 minute. ### Claim 10 (depends on 1) The process of claim 1, wherein the alloy comprises no more than 1% of each of silicon, phosphorus, and sulfur by weight. ### Claim 11 (depends on 1) The process of claim 1, wherein the alloy further comprises manganese in an amount of up to 5% by weight. ### Claim 12 (depends on 1) The process of claim 1, wherein the alloy further comprises iron in an amount of up to 5% by weight. ### Claim 13 (depends on 1) The process of claim 1, wherein the alloy further comprises both manganese and iron in a concentration of up to about 3% each, by weight. ### Claim 14 (depends on 1) The process of claim 1, wherein a sum of cobalt and platinum comprises from 48% to about 60% by weight of the alloy. ### Claim 15 (depends on 1) The process of claim 1, wherein the alloy comprises: about 20-37% cobalt; about 20-30% platinum; about 19-21% chromium; about 14-16% tungsten; about 9-11% nickel; and about 1-2% manganese. ### Claim 16 (depends on 15) The process of claim 15, wherein the alloy comprises one or more trace elements as follows: 0-3% iron; 0-0.03% sulfur; 0-0.04% phosphorus; and 0-0.04% silicon. ### Claim 17 A process for the production of a cobalt-chromium alloy including tungsten and platinum, the process comprising: providing an alloy formed from cobalt, chromium, tungsten, and platinum, wherein the alloy includes precipitate inclusions, so as to not be substantially homogenous; heating the alloy to a temperature from about 1225° C. to 1275° C. for a time period from about 20 to about 40 minutes to remove the precipitate inclusions from the alloy, providing a substantially homogenous alloy; and quenching the alloy to 600° C. or less within 5 minutes. ### Claim 18 (depends on 17) The process of claim 17, wherein the precipitate inclusions comprise tungsten. ### Claim 19 (depends on 17) The process of claim 17, wherein the precipitate inclusions comprise Co3W. ### Claim 20 A process for the production of a stent formed from a cobalt-chromium alloy including tungsten and platinum, the process comprising: providing an alloy in the form of a tube or a rod formed from cobalt, chromium, tungsten, and platinum, wherein the alloy includes precipitate inclusions, so as to not be substantially homogenous; heating the alloy to a temperature from about 1225° C. to 1275° C. for a time period from about 20 to about 40 minutes to remove the precipitate inclusions from the alloy, providing a substantially homogenous alloy; quenching the alloy to 600° C. or less within 5 minutes; and drawing the tube or rod.