# US 10,478,529 B2 · Magnesium alloy with adjustable degradation rate

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- Number: US 10,478,529 B2
- Document ID: US10478529B2
- Status: Granted
- Kind: B2
- Application number: 14/774,264
- Filed: 2014-03-11
- Published: 2016-01-28
- Granted: 2019-11-19
- Earliest claimed: 2013-03-14
- Assignees: DePuy Synthes Products, Inc.
- Applicants: Depuy Synthes Products, Inc.
- Inventors: Thomas Imwinkelried; Stefan Beck; Peter Uggowitzer; Joerg Loeffler
- Web page: https://patentgrep.com/patent/US10478529B2

## CPC

- A61L 31/022: {Metals or alloys}
- A61B 17/84: Fasteners therefor {or fasteners being internal fixation devices}
- A61F 2/44: for the spine, e.g. vertebrae or spinal discs
- 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 27/047: {Other specific metals or alloys not covered by A61L27/042 - A61L27/045 or A61L27/06}
- A61L 27/58: Materials at least partially resorbable by the body
- A61L 31/148: {Materials at least partially resorbable by the body}
- C22C 23/04: with zinc or cadmium as the next major constituent
- C22F 1/06: of magnesium or alloys based thereon
- 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)
- A61B: DIAGNOSIS; SURGERY; IDENTIFICATION (usefulness limited to only animals A61D)
- 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)
- C22C: ALLOYS (treatment of alloys C21D, C22F)
- C22F: CHANGING THE PHYSICAL STRUCTURE OF NON-FERROUS METALS AND NON-FERROUS ALLOYS (surface treatment of metallic material involving at least one process provided for in class C23 and at least one process covered by this subclass, C23F17/00)

## Abstract

An alloy and an implant having a three-dimensional structure based on such alloy. The alloy comprises a MgZnCa alloy containing nanosized precipitates being less noble than the Mg matrix alloy and having a Zn content ranging 0.1 wt. % Zn to 2 wt. % Zn and a calcium content ranging from 0.2 wt. % to 0.5 wt. %, and having one or more other elements, with the remainder being Mg. Any second phase generated during the solidification process may be completely dissolved by a solution heat treatment. Finely dispersed nanosized precipitates can then be generated by a subsequent aging heat treatment step. These precipitates are used to “pin” the grain boundaries and to prevent the coarsening of the grain structure during further processing to achieve grain sizes below 5 μm.

## Claims

### Claim 1

A method of producing a composition comprising a Mg matrix and nanosized precipitates; wherein the composition has a Zn content ranging from 0.1 wt. % Zn to 2.0 wt. % Zn; a Ca content ranging from 0.2 wt. % Ca to 0.5 wt. % Ca; a content of one or more other elements; and a remainder content being Mg; wherein the nanosized precipitates are less noble or more noble than the Mg matrix, or a mixture thereof, the method comprising the steps of:
(a) casting a mixture containing (i) magnesium having a purity of at least 99.96 wt. %; (ii) from 0.1 wt. % to 2.0 wt. % zinc having a purity of at least 99.9 wt. %; and (iii) from 0.2 wt. % to 0.5 wt. % calcium metal having a purity of at least 99.9 wt. %;
(b) solution heat treating of the cast alloy at two different temperatures wherein a first temperature is below an eutectic temperature of Mg—Zn and a second temperature is above the eutectic temperature of the ternary Mg—Zn—Ca system to thereby form a MgZnCa alloy containing from 0.1 wt. % Zn to 2 wt. % Zn, and a calcium content ranging from 0.2 wt. % to 0.5 wt. %, and having a content of one or more other elements, with the remainder being Mg,
(c) age heat treating between 100° C. and 300° C. to create dispersed nanosized precipitates prior to extrusion;
(d) extruding the alloy into a desired shape; and
(e) low temperature annealing of the shaped alloy at about 150° C. to about 250° C.

### Claim 2 (depends on 1)

The method of claim 1, wherein the first temperature is from about 330° C. to about 370° C.

### Claim 3 (depends on 1)

The method of claim 1, wherein the second temperature is from about 400° C. to about 460° C.

### Claim 4 (depends on 1)

The method of claim 1, wherein the content of the one or more other elements is less than about 0.1 wt % of the composition.

### Claim 5 (depends on 1)

The method of claim 1, wherein at least some of the one or more other elements are located in a secondary phase.

### Claim 6 (depends on 5)

The method of claim 5, wherein the one or more other elements located in the secondary phase are less than 0.04 wt % of the composition.

### Claim 7 (depends on 1)

The method of claim 1, wherein the alloy composition contains less than 400 ppm of total other elements.

### Claim 8 (depends on 1)

The method of claim 1, wherein the one or more other elements comprise Fe, Cu, Ni, Co, Si, Mn, Al, Zr or P.

### Claim 9 (depends on 1)

The method of claim 1, wherein the low temperature annealing is performed at 200° C.

### Claim 10 (depends on 1)

The method of claim 1, wherein the low temperature annealing is performed from about 1 hour to about 100 hours.