Ultrapure magnesium alloy with adjustable degradation rate

Patent metadata

Field	Value
Publication number	US-9469889-B2
Application number	US-201313827008-A
Country	US
Kind code	B2
Filing date	Mar 14, 2013
Priority date	Aug 31, 2012
Publication date	Oct 18, 2016
Grant date	Oct 18, 2016

Abstract

An alloy and an implant having a three-dimensional structure based on such alloy. The alloy comprises a monophasic MgZn alloy containing from 2.0 wt. % Zn to 6 wt. % Zn, having less than 0.001 wt. % of one or more other elements with the remainder being Mg. In some embodiments, the alloy is substantially free of microgalvanic elements. In some embodiments, the alloy includes a MgZnCa alloy containing nanosized precipitates being less noble than the Mg matrix alloy and having a Zn content ranging from 3.0 wt. % Zn to 6 wt. % Zn and a calcium content ranging from 0.0005 wt. % to 1.0 wt. %, having less than 0.001 wt. % of one or more other elements with the remainder being Mg. In other embodiments, the alloy includes a MgZnCa alloy containing nanosized precipitates being less noble than the Mg matrix alloy, a plurality of nanosized precipitates being more noble than the Mg matrix and having a Zn content ranging from 3.0 wt. % Zn to 6 wt. % Zn, a calcium content ranging from 0.0005 wt. % to 1.0 wt. %, having less than 0.001 wt. % of one or more other elements with the remainder being Mg.

First claim

We claim:

1. A medical implant comprising:
a MgZnCa alloy containing nanosized precipitates, wherein the nanosized precipitates are less noble than a MgZn alloy, and wherein the MgZnCa alloy has a Zn content ranging from 3.0 wt. % Zn to 6 wt. % Zn and a calcium content ranging from 0.0005 wt. % Ca to 1.0 wt. % Ca, less than 0.001 wt. % of one or more other elements and with the remainder of the alloy being Mg, wherein the Mg has a purity of at least 99.997 wt. %, the Zn has a purity of at least 99.999 wt. %, and the Ca has a purity of at least 99.9 wt. %.

2. The implant according to claim 1 , wherein the MgZnCa alloy contains less than 5 ppm of total other elements.

3. The implant according to claim 1 , wherein the MgZnCa alloy contains less than 2 ppm of total other elements.

4. The implant according to claim 1 , wherein the MgZnCa alloy contains less than 1 ppm of total other elements.

5. The implant according to claim 1 , wherein the MgZnCa alloy contains less than 0.5 ppm of total other elements.

6. The implant according to claim 1 , wherein the other elements comprise one or more of Fe, Cu, Ni, Co, Si, Mn, Al, Zr, and P.

7. The implant according to claim 1 , wherein the MgZnCa alloy contains less than 0.1 ppm Ni.

8. The implant according to claim 1 , wherein the MgZnCa alloy contains less than 0.001 wt. % of rare earth elements.

9. The implant according to claim 8 , wherein the rare earth elements comprise one or more of Sc, Y, the Lanthanide elements having atomic numbers ranging from 57-71, and the Actinide elements having atomic numbers ranging from 89-103.

10. The implant according to claim 1 , further comprising a plurality of nanosized precipitates being more noble than the MgZn alloy, wherein the nanosized precipitates comprise Mn—Zn.

11. The implant according to claim 1 , wherein the MgZnCa alloy has a grain size of less than 10 μm.

12. The implant according to claim 1 , wherein the MgZnCa alloy has a yield strength of at least 200 MPa.

13. The implant according to claim 1 , wherein the MgZnCa alloy has an ultimate tensile strength of at least 250 MPa.

14. The implant according to claim 1 , wherein the MgZnCa alloy has at least 15% elongation at break.

15. A medical implant comprising: a MgZnCa alloy, having a Zn content ranging from 3.0 wt. % Zn to 6 wt. % Zn, the Zn having a purity of at least 99.999 wt. %, a calcium content ranging from 0.0005 wt. % Ca to 1.0 wt. % Ca, the Ca having a purity of at least 99.9 wt. %, less than 0.001 wt. % of one or more other elements located in a secondary phase and with the remainder of the alloy being Mg having a purity of at least 99.997 wt. %, wherein the MgZnCa alloy contains nanosized precipitates being less noble than the Mg remainder.

Assignees

• Depuy Synthes Products Inc

Inventors

• Imwinkelried Thomas
• Beck Stefan
• Uggowitzer Peter
• Loeffler Joerg

Classifications

• C22F1/06

  of magnesium or alloys based thereon · CPC title

• A61L2400/12

  Nanosized materials, e.g. nanofibres, nanoparticles, nanowires, nanotubes; Nanostructured surfaces · CPC title

• A61L31/148

  Materials at least partially resorbable by the body · CPC title

• A61L27/047 Primary

  Other specific metals or alloys not covered by A61L27/042 - A61L27/045 or A61L27/06 · CPC title

• A61B17/84

  Fasteners therefor {or fasteners being internal fixation devices} · CPC title