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    • 专利摘要:
    COMPOSITIONS OF MAGNESIUM ALLOY, ITS PRODUCTION METHODS, AND IMPLANT. The present invention relates to an alloy and an implant that has a three-dimensional structure based on such an alloy. The alloy comprises a single-phase MgZn alloy containing from 2.0% by weight of Zn to 6% by weight of Zn, which has less than 0.001% by weight of one or more other elements in which the remainder is Mg. In some embodiments, the alloy is substantially free of microgalvanic elements. In some embodiments, the alloy includes an MgZnCa alloy that contains nanodimensioned precipitates that are less noble than an Mg matrix alloy and that have a Zn content in the range of 3.0% by weight of Zn to 6% by weight of Zn Zn and a calcium content in the range of 0.0005% by weight to 1.0% by weight, which has less than 0.001% by weight of one or more other elements, the remainder being Mg. In other embodiments, the alloy includes an MgZnCa alloy that contains nano-sized precipitates that are less noble than an Mg matrix alloy, a plurality of nano-sized precipitates that are more noble than the Mg matrix and have a content (...) .
    公开号:BR112015004503B1
    申请号:R112015004503-0
    申请日:2013-08-29
    公开日:2021-03-02
    发明作者:Thomas Imwinkelried；Stefan Beck；Peter Uggowitzer；Joerg Loeffler
    申请人:Synthes Gmbh；
    IPC主号:
    专利说明:

    [0001] This application claims priority benefit from US Provisional Patent Application No. 61 / 695,621, filed on August 31, 2012 and US Non-Provisional Patent Application No. 13 / 827,008 filed on March 14, 2013, all of which are incorporated by reference in their entirety. FIELD OF THE INVENTION
    [0002] The present invention relates to magnesium alloys that have improved degradation properties. BACKGROUND OF THE INVENTION
    [0003] Magnesium implants were clinically used to treat bone fractures by several surgeons in the 1930s. For example, J. Verbrugge (1934) used pure magnesium and Mg alloy implants with 8% Al in 21 patients . However, after the Second World War, the use of magnesium as a resorbable implant material declined. Currently, researchers have renewed their interest in resorbable magnesium implants. The main focus of magnesium research is the development of alloys and coatings. The main objectives are to control the rate of degradation, to prevent the formation of gas bubbles during degradation and to avoid potentially harmful alloying elements. Therefore, there is a need for magnesium alloys whose rate of degradation can be controlled and / or adjusted as desired.
    [0004] Pure commercial grade magnesium (3N-Mg) does not show uniform degradation in vitro or in vivo. It is believed that the presence of impurities in the commercial product increases the rate of degradation due to the formation of microgalvanic elements, which include iron (Fe), copper (Cu) and nickel (Ni). Consequently, there is a need for an ultrapure magnesium material for medical applications, including surgical implants.
    [0005] To avoid secondary phases, other contaminants such as cobalt (Co), silicon (Si), manganese (Mn) and aluminum (Al) also need to be controlled. Often, the presence of a single contaminant can lower the solubility limit for other contaminants. The presence of these trace elements can change the eutectic temperature in the magnesium phase diagram. During the solidification process, contaminants can accumulate in interdendritic spaces and induce the formation of secondary phases. The phases cannot be eliminated by means of subsequent thermomechanical treatments.
    [0006] The modalities of the present invention overcome one or more of the challenges mentioned above. BRIEF SUMMARY OF THE INVENTION
    [0007] The present disclosure provides several exemplary embodiments of the present invention, some of which are discussed below.
    [0008] In one aspect, the present invention provides an alloy composition and an implant that has a three-dimensional structure based on such an alloy composition. In one embodiment, the composition includes a single-phase MgZn alloy containing from 2.0% by weight of Zn to 6% by weight of Zn, less than 0.001% by weight of one or more other elements located in a secondary phase and in the rest is Mg. In one embodiment, the alloy is substantially free of microgalvanic elements. In another exemplary embodiment, the composition consists essentially of a single-phase MgZn alloy containing from 2.0% by weight of Zn to 6% by weight of Zn, less than 0.001% by weight of one or more other elements located in a secondary phase and the remainder is Mg. In such an embodiment, the alloy is substantially free of microgalvanic elements. In yet another exemplary embodiment, the composition consists of a single-phase MgZn alloy containing from 2.0% by weight of Zn to 6% by weight of Zn, less than 0.001% by weight of one or more other elements located in a secondary phase and the remainder is Mg. In such an embodiment, the alloy is substantially free of microgalvanic elements.
    [0009] In one embodiment, the MgZn alloy contains less than 5 ppm of other total elements. In another embodiment, the MgZn alloy contains less than 2 ppm of other total elements. In yet another embodiment, the MgZn alloy contains less than 1 ppm of other total elements. In yet another embodiment, the MgZn alloy contains less than 0.5 ppm of other total elements.
    [00010] In another embodiment, the composition includes an MgZnCa alloy that contains nanodimensioned precipitates that are less noble than an MgZn alloy and that have a Zn content in the range of 3.0% by weight of Zn to 6% in weight of Zn and a calcium content in the range of 0.0005% by weight to 1.0% by weight, less than 0.001% by weight of one or more other elements located in a secondary phase, with the remainder being Mg . In another embodiment, the composition consists essentially of an MgZnCa alloy that contains noble nanodimensioned precipitates that are less noble than an MgZn alloy and that have a Zn content in the range of 3.0% by weight of Zn to 6% by weight. weight of Zn and a calcium content in the range of 0.0005% by weight to 1.0% by weight, less than 0.001% by weight of one or more other elements located in a secondary phase and the remainder being Mg. In another embodiment, the composition consists of an MgZnCa alloy that contains nanodimensioned precipitates that are less noble than an MgZn alloy and that have a Zn content in the range of 3.0% by weight of Zn to 6% by weight of Zn Zn and a calcium content in the range of 0.0005% by weight to 1.0% by weight, less than 0.001% by weight of one or more other elements located in a secondary phase and the remainder being Mg.
    [00011] In one embodiment, the MgZnCa alloy contains less than 5 ppm of other total elements. In another embodiment, the MgZnCa alloy contains less than 2 ppm of other total elements. In yet another embodiment, the MgZnCa alloy contains less than 1 ppm of other total elements. In yet another embodiment, the MgZnCa alloy contains less than 0.5 ppm of other total elements.
    [00012] In some other modalities, the less noble nanodimensioned precipitates comprise Mg6Zn3Ca2.
    [00013] In another embodiment, the composition includes an MgZnCa alloy that contains nanodimensioned precipitates and that have a Zn content in the range of 3.0% by weight of Zn to 6% by weight of Zn and a content of calcium in the range from 0.0005% by weight to 1.0% by weight, less than 0.001% by weight of one or more other elements located in a secondary phase, in which the remainder is Mg and in which the nanodimensioned precipitates are less noble than the remaining Mg. In another embodiment, the composition consists essentially of an MgZnCa alloy that contains noble nanodimensioned precipitates and which have a Zn content in the range of 3.0% by weight of Zn to 6% by weight of Zn and a content of calcium in the range from 0.0005% by weight to 1.0% by weight, less than 0.001% by weight of one or more other elements located in a secondary phase and in which the remainder is Mg and in which the nanodimensioned precipitates are less noble than the remaining Mg. In another embodiment, the composition consists of an MgZnCa alloy that contains nanodimensioned precipitates and which have a Zn content in the range of 3.0% by weight of Zn to 6% by weight of Zn and a calcium content in the range of 0.0005% by weight to 1.0% by weight, less than 0.001% by weight of one or more other elements located in a secondary phase and where the remainder is Mg and where the nanodimensioned precipitates are less noble than Mg remaining.
    [00014] In one embodiment, the MgZnCa alloy contains less than 5 ppm of other total elements. In another embodiment, the MgZnCa alloy contains less than 2 ppm of other total elements. In yet another embodiment, the MgZnCa alloy contains less than 1 ppm of other total elements. In yet another embodiment, the MgZnCa alloy contains less than 0.5 ppm of other total elements.
    [00015] In some other embodiments, the less noble nanodimensioned precipitates comprise Mg6Zn3Ca2.
    [00016] In another embodiment, the composition includes an MgZnCa alloy that contains nanodimensioned precipitates that are less noble than an MgZn alloy, a plurality of nanodimensioned precipitates that are more noble than an MgZn alloy, and that have a content of Zn in the range of 3.0% by weight of Zn to 6% by weight of Zn and a calcium content in the range of 0.0005% by weight to 1.0% by weight, less than 0.001% by weight of one or plus other elements located in a secondary phase in which the remainder is Mg. In another embodiment, the composition consists essentially of an MgZnCa alloy that contains nanodimensioned precipitates that are less noble than an MgZn alloy, a plurality of nanodimensioned precipitates that are more noble than an MgZn alloy, and that have a Zn content in the range of 3.0% by weight of Zn to 6% by weight of Zn and a calcium content in the range of 0.0005% by weight to 1.0% by weight, less than 0.001% by weight of one or more other elements located in a secondary phase and the remainder being Mg. In another embodiment, the composition consists of an MgZnCa alloy that contains nanodimensioned precipitates that are less noble than an MgZn alloy, a plurality of nanodimensioned precipitates that are more noble than the Mg matrix, and that have a Zn content in the range of 3.0% by weight of Zn to 6% by weight of Zn and a calcium content in the range of 0.0005% by weight to 1.0% by weight, less than 0.001% by weight of one or more others elements located in a secondary phase and the remainder being Mg.
    [00017] In one embodiment, the MgZnCa alloy contains less than 5 ppm of other total elements. In another embodiment, the MgZnCa alloy contains less than 2 ppm of other total elements. In yet another embodiment, the MgZnCa alloy contains less than 1 ppm of other total elements. In yet another embodiment, the MgZnCa alloy contains less than 0.5 ppm of other total elements.
    [00018] In some of these modalities, the nanodimension precipitates less noble than Mg comprise Mg6Zn3Ca2. In other of these modalities, the nanodimensioned precipitates that are more noble than the Mg matrix comprise Mn-Zn.
    [00019] In some embodiments of the alloys according to the present invention, each alloy has a grain size of less than 10 μm. In some alloys of the present invention, each alloy has a yield strength of at least 200 MPa. In some embodiments, each alloy has a yield strength of at least 200 MPa. In one embodiment, each alloy has a tensile strength of at least 250 MPa. In another mode, each alloy has at least 15% elongation at break. In yet another embodiment, each alloy has an in vitro degradation rate of less than 0.5 mg / cm2 day as measured in a simulated body fluid.
    [00020] In other modalities, the implant is an orthopedic implant. In such embodiments, the orthopedic implant comprises one or more of the following: a pin, a thread, a clamp, a plate, a rod, a tack, a screw, a locking screw and an intramedullary pin, an anchor, a pin, a plug, a stake, a sleeve, a mesh, a transconector, a nut, a shaped body, spinal cage, a wire, a Kirschner wire, a woven structure, a claw, a splint, a frame, a foam and a beehive structure. In some other embodiments, the implant has a lower rate of degradation compared to magnesium alloy implants that contain microgalvanic impurities.
    [00021] In other modalities, the implant is a non-orthopedic implant. In such modalities, the non-orthopedic implant includes a cardiovascular stent, a neural stent, or a vertebroplasty stent.
    [00022] In yet another modality of the implant, each alloy has an in vitro degradation rate of less than 0.5 mg / cm2 day as measured in a simulated body fluid.
    [00023] In one aspect, the present invention provides a method of producing an alloy according to the modalities described herein. In one embodiment, the method comprises: (a) melting an alloy that contains (i) ultrapure magnesium that has a purity of at least 99.997% by weight and that has less than 0.001% by weight of one or more other elements; and (ii) from 2.0 to 6%, by weight, of zinc, which has a purity of at least 99.999% by weight, the said smelting being carried out in an inert atmosphere and in an inert reaction vessel; (b) heat the molten alloy at two different temperatures, the first temperature being below the eutectic temperature of Mg-Zn and the second temperature being above the eutectic temperature of the ternary Mg-Zn-Ca system to form, in this way, a single-phase MgZn alloy containing from 2.0% by weight of Zn to 6% by weight of Zn, which has less than 0.001% by weight of one or more other elements in which the remainder is Mg; and (c) extruding the alloy in a desired shape.
    [00024] In some embodiments, the method of producing an alloy according to the present invention comprises: (a) melting an alloy containing (i) ultrapure magnesium which has a purity of at least 99.997% by weight and which has less than 0.001% by weight of one or more other elements; (ii) from 3.0% to 6% by weight of zinc which has a purity of at least 99.999% by weight; and (iii) from 0.02% by weight to 1.0% by weight of calcium metal, which has a purity of at least 99.9% by weight, and said smelting is carried out in an inert atmosphere and in a inert reaction vessel; (b) heat the molten alloy at two different temperatures, the first temperature being below the eutectic temperature of Mg-Zn and the second temperature being above the eutectic temperature of the ternary Mg-Zn-Ca system to form, in this way, an MgZnCa alloy containing from 3.0% by weight of Zn to 6% by weight of Zn; and a calcium content in the range of 0.0005% by weight to 1.0% by weight, which is less than 0.001% by weight of one or more other elements and the remainder being Mg; (c) extruding the alloy in a desired shape; and (d) heating the shaped alloy to at least 140 ° C to form more noble nanodimensioned precipitates dispersed over an MgZnCa alloy. In an additional embodiment, the method comprises heating to at least 230 ° C to form more noble precipitates dispersed over an MgZn alloy. DETAILED DESCRIPTION OF THE INVENTION
    [00025] Detailed reference is made to the various modalities of the present revelation.
    [00026] In one aspect, the present invention relates to a composition that comprises a high purity magnesium alloy. In one embodiment, an alloy composition comprises a single-phase MgZn alloy containing from 2.0% by weight of Zn to 6% by weight of Zn, which has less than 0.001% by weight of one or more other elements and in which the rest is Mg. In another embodiment, the alloy composition consists essentially of a single-phase MgZn alloy containing from 2.0% by weight of Zn to 6% by weight of Zn, less than 0.001% by weight of one or more other elements and where the remainder is Mg. In yet another embodiment, the alloy composition consists of a single-phase MgZn alloy containing from 2.0% by weight of Zn to 6% by weight of Zn, which has less than 0.001% by weight of one or more other elements and the remainder is Mg. In some of these modalities, the single-phase MgZn alloy is substantially free of microgalvanic elements.
    [00027] In another aspect, the present invention relates to an implant composition produced from a high purity magnesium alloy. In one embodiment, the implant having a three-dimensional structure comprises a single-phase MgZn alloy containing from 2.0% by weight of Zn to 6% by weight of Zn, which has less than 0.001% by weight of one or more other elements and where the remainder is Mg. In another embodiment, the implant has a three-dimensional structure and comprises a composition that consists essentially of a single-phase MgZn alloy that contains from 2.0% by weight of Zn to 6% by weight of Zn, which has less than 0.001% in weight of one or more other elements and the remainder being Mg. In yet another embodiment, the implant has a three-dimensional structure and comprises a composition consisting of a single-phase MgZn alloy that contains from 2.0% by weight of Zn to 6% by weight of Zn, which has less than 0.001% in weight of one or more other elements and the remainder being Mg. In some of these modalities, the single-phase MgZn alloy is substantially free of microgalvanic elements.
    [00028] In general, the Zn content in the Mg-Zn alloy and in an Mg-Zn alloy used in an implant composition, according to the present invention, can be in the range of 2% by weight to 6% by weight. In one embodiment, the alloy has a Zn content that can be independently selected from the ranges of 2% by weight to 3% by weight, from 2.1% by weight to 3% by weight, from 2.2% by weight to 3% by weight, 2.3% by weight to 3% by weight, 2.4% by weight to 3% by weight, 2.5% by weight to 3% by weight, 2.6% by weight weight at 3% by weight, from 2.7% by weight to 3% by weight, from 2.8% by weight to 3% by weight, from 2.9% by weight to 3% by weight, from 2% by weight at 4% by weight, from 2.1% by weight to 4% by weight, from 2.2% by weight to 4% by weight, from 2.3% by weight to 4% by weight, from 2.4 % by weight to 4% by weight, from 2.5% by weight to 4% by weight, from 2.6% by weight to 4% by weight, from 2.7% by weight to 4% by weight, from 2 , 8% by weight to 4% by weight, from 2.9% by weight to 4% by weight, from 3% by weight to 4% by weight, from 3.1% by weight to 4% by weight, from 3 , 2% by weight to 4% by weight, from 3.3% by weight to 4% by weight, from 3.4% by weight to 4% by weight, from 3.5% by weight to 4% by weight, 3.6% by weight to 4% by weight, 3.7% by weight to 4% by weight, 3.8% by weight to 4% by weight, 3.9% by weight to 4% by weight weight of 2% in weight at 5% by weight, from 2.1% by weight to 5% by weight, from 2.2% by weight to 5% by weight, from 2.3% by weight to 5% by weight, from 2.4 % by weight to 5% by weight, from 2.5% by weight to 5% by weight, from 2.6% by weight to 5% by weight, from 2.7% by weight to 5% by weight, from 2 , 8% by weight to 5% by weight, from 2.9% by weight to 5% by weight, from 3% by weight to 5% by weight, from 3.1% by weight to 5% by weight, from 3 , 2% by weight to 5% by weight, 3.3% by weight to 5% by weight, 3.4% by weight to 5% by weight, 3.5% by weight to 5% by weight, 3.6% by weight to 5% by weight, 3.7% by weight to 5% by weight, 3.8% by weight to 5% by weight, 3.9% by weight to 5% by weight weight, from 4% by weight to 5% by weight, from 4.1% by weight to 5% by weight, from 4.2% by weight to 5% by weight, from 4.3% by weight to 5% by weight from 4.4% by weight to 5% by weight, from 4.5% by weight to 5% by weight, from 4.6% by weight to 5% by weight, from 4.7% by weight to 5 % by weight, from 4.8% by weight to 5% by weight, from 4.9% by weight to 5% by weight, from 2% by weight to 6% by weight, from 2.1% by weight to 6 % by weight, from 2.2% by weight to 6% by weight, from 2.3% by weight to 6% by weight so, from 2.4% by weight to 6% by weight, from 2.5% by weight to 6% by weight, from 2.6% by weight to 6% by weight, from 2.7% by weight to 6% % by weight, from 2.8% by weight to 6% by weight, from 2.9% by weight to 6% by weight, from 3% by weight to 6% by weight, from 3.1% by weight to 6% % by weight, from 3.2% by weight to 6% by weight, from 3.3% by weight to 6% by weight, from 3.4% by weight to 6% by weight, 3.5% by weight to 6% by weight, from 3.6% by weight to 6% by weight, from 3.7% by weight to 6% by weight, from 3.8% by weight to 6% by weight, from 3.9% by weight to 6% by weight, from 4% by weight to 6% by weight, from 4.1% by weight to 6% by weight, from 4.2% by weight to 6% by weight, from 4.3% by weight to 6% by weight, from 4.4% by weight to 6% by weight, from 4.5% by weight to 6% by weight, from 4.6% by weight to 6% by weight, from 4, 7% by weight to 6% by weight, from 4.8% by weight to 6% by weight, from 4.9% by weight to 6% by weight, from 5% by weight to 6% by weight, from 5, 1% by weight to 6% by weight, from 5.2% by weight to 6% by weight, from 5.3% by weight to 6% by weight, from 5.4% by weight to 6% by weight, 5.5% by weight, to 6% by weight, from 5.6% by weight to 6% by weight, 5.7% by weight at 6% by weight, from 5.8% by weight to 6% by weight, or from 5.9% by weight to 6% by weight.
    [00029] In another embodiment of the present invention, an MgZnCa alloy comprises a plurality of nanodimensioned precipitates that are less noble than an MgZn alloy, a Zn content in the range of 3.0% by weight of Zn to 6% in Zn weight, a calcium content in the range of 0.0005% by weight to 1.0% by weight, has less than 0.001% by weight of one or more other elements, the remainder being Mg. In yet another embodiment, the MgZnCa alloy essentially consists of a plurality of nanodimensioned precipitates that are less noble than an MgZn alloy, have a Zn content in the range of 3.0% by weight of Zn to 6% by weight of Zn Zn, a calcium content in the range of 0.0005% by weight to 0.25% by weight, has less than 0.001% by weight of one or more other elements, the remainder being Mg. In another embodiment, an MgZnCa alloy consists of a plurality of nanodimensioned precipitates that are less noble than an MgZn alloy, which has a Zn content in the range of 3.0% by weight of Zn to 6% by weight of Zn , a calcium content in the range of 0.0005% by weight to 1.0% by weight, has less than 0.001% by weight of one or more other elements, the remainder being Mg. In some of these modalities, the nanodimensioned precipitates, which are less noble than Mg-Zn, comprise Mg6Zn3Ca2.
    [00030] In another embodiment of the present invention, the implant has a three-dimensional structure and comprises an MgZnCa alloy. In one embodiment, the implant has a three-dimensional structure produced from an MgZnCa alloy that comprises a plurality of nanodimensioned precipitates that are less noble than an MgZn alloy, has a Zn content in the range of 3.0% by weight of Zn at 6% by weight of Zn, a calcium content in the range of 0.0005% by weight at 1.0% by weight, has less than 0.001% by weight of one or more other elements, the remainder being Mg . In another embodiment, the implant has a three-dimensional structure and comprises a composition that consists essentially of an MgZnCa alloy that contains a plurality of nanodimensioned precipitates that are less noble than an MgZn alloy, has a Zn content in the range of 3, 0% by weight of Zn to 6% by weight of Zn, a calcium content in the range of 0.0005% by weight to 1.0% by weight, which is less than 0.001% by weight of one or more other elements, where the remainder is Mg. In another embodiment, the implant has a three-dimensional structure and comprises a composition that consists of an MgZnCa alloy that contains a plurality of nanodimensioned precipitates that are less noble than an MgZn alloy, has a Zn content in the range of 3.0 % by weight of Zn to 6% by weight of Zn, a calcium content in the range of 0.0005% by weight to 1.0% by weight, has less than 0.001% by weight of one or more other elements, where the rest is Mg. In such embodiments, the less noble nanodimensioned precipitates comprise Mg6Zn3Ca2.
    [00031] The skilled person will understand that a precipitate that is less noble than Mg-Zn will necessarily be less noble than Mg due to the fact that Mg-Zn is more noble than Mg. Therefore, the above modalities of MgZnCa and the implants produced from it can also be expressed as follows. In another embodiment, the composition includes an MgZnCa alloy that contains nanodimensioned precipitates and that have a Zn content in the range of 3.0% by weight of Zn to 6% by weight of Zn and a calcium content in the range of 0 .0005% by weight to 1.0% by weight, less than 0.001% by weight of one or more other elements located in a secondary phase, where the remainder is Mg and where the nanodimensioned precipitates are less noble than Mg remaining. In another embodiment, the composition consists essentially of an MgZnCa alloy that contains noble nanodimensioned precipitates and which have a Zn content in the range of 3.0% by weight of Zn to 6% by weight of Zn and a content of calcium in the range from 0.0005% by weight to 1.0% by weight, less than 0.001% by weight of one or more other elements located in a secondary phase and in which the remainder is Mg and in which the nanodimensioned precipitates are less noble than the remaining Mg. In another embodiment, the composition consists of an MgZnCa alloy that contains nanodimensioned precipitates and which have a Zn content in the range of 3.0% by weight of Zn to 6% by weight of Zn and a calcium content in the range of 0.0005% by weight to 1.0% by weight, less than 0.001% by weight of one or more other elements located in a secondary phase and where the remainder is Mg and where the nanodimensioned precipitates are less noble than Mg remaining.
    [00032] In yet another embodiment, an MgZnCa alloy comprises a plurality of nano-sized precipitates that are less noble than an MgZn alloy and a plurality of nano-sized precipitates that are more noble than an MgZn alloy, a Zn content in the range from 3.0% by weight of Zn to 6% by weight of Zn, a calcium content in the range of 0.0005% by weight to 1.0% by weight, has less than 0.001% by weight of one or more others elements, the rest of which is Mg. In another embodiment, an MgZnCa alloy essentially consists of a plurality of nano-sized precipitates that are less noble than an MgZn alloy and a plurality of nano-sized precipitates that are more noble than an MgZn alloy, have a Zn content in the range of 3.0% by weight of Zn to 6% by weight of Zn, a calcium content in the range of 0.0005% by weight to 1.0% by weight, has less than 0.001% by weight of one or more other elements , with the remainder being Mg. In another embodiment, an MgZnCa alloy consists of a plurality of nano-sized precipitates that are less noble than an MgZn alloy and a plurality of nano-sized precipitates that are more noble than an MgZn alloy, have a Zn content in the range of 3 , 0% by weight of Zn to 6% by weight of Zn, a calcium content in the range of 0.0005% by weight to 1.0% by weight, has less than 0.001% by weight of one or more other elements, where the remainder is Mg. In such embodiments, the less noble nanodimension precipitates comprise Mg6Zn3Ca2 and the more noble nanodimension precipitates comprise Mg-Zn.
    [00033] In some other embodiments, an implant according to the present invention has a three-dimensional structure and comprises an MgZnCa alloy that has a plurality of nano-sized precipitates that are less noble than an MgZn alloy and a plurality of nano-sized precipitates that are nobler than an MgZn alloy. In one embodiment, the implant has a three-dimensional structure and comprises a composition comprising an MgZnCa alloy that contains a plurality of nanodimensioned precipitates that are less noble than an MgZn alloy and a plurality of nanodimensioned precipitates that are more noble than an alloy of MgZn, and has a Zn content in the range of 3.0% by weight of Zn to 6% by weight of Zn, a calcium content in the range of 0.0005% by weight to 1.0% by weight, has less 0.001% by weight of one or more other elements, the remainder being Mg. In another embodiment, the implant has a three-dimensional structure and comprises a composition consisting essentially of an MgZnCa alloy that contains a plurality of nanodimensioned precipitates that are less noble than an MgZn alloy and a plurality of nanodimensioned precipitates that are more noble than an MgZn alloy, has a Zn content in the range of 3.0% by weight of Zn to 6% by weight of Zn, a calcium content in the range of 0.0005% by weight to 1.0% by weight, it has less than 0.001% by weight of one or more other elements, the remainder being Mg. In another embodiment, the implant has a three-dimensional structure and comprises a composition consisting of an MgZnCa alloy that contains a plurality of nano-sized precipitates that are less noble than an MgZn alloy and a plurality of nano-sized precipitates that are more noble than one MgZn alloy, has a Zn content in the range of 3.0% by weight of Zn to 6% by weight of Zn, a calcium content in the range of 0.0005% by weight to 1.0% by weight, and it has less than 0.001% by weight of one or more other elements, the remainder being Mg. In some of these modalities, nanodimensioned precipitates less noble than Mg comprise Mg6Zn3Ca2. In other of these modalities, the nanodimensioned precipitates that are more noble than the Mg matrix comprise Mn-Zn.
    [00034] In general, the Zn content in the various modalities of the MgZnCa alloy and of an implant based on the various modalities of the MgZnCa alloy, according to the present invention, can be any suitable amount. In one embodiment, the MgZnCa alloy has a Zn content that can be independently selected from the ranges of 2% by weight to 3% by weight, from 2.1% by weight to 3% by weight, from 2.2% by weight. weight at 3% by weight, from 2.3% by weight to 3% by weight, from 2.4% by weight to 3% by weight, from 2.5% by weight to 3% by weight, from 2.6 % by weight to 3% by weight, from 2.7% by weight to 3% by weight, from 2.8% by weight to 3% by weight, from 2.9% by weight to 3% by weight, from 2 % by weight to 4% by weight, from 2.1% by weight to 4% by weight, from 2.2% by weight to 4% by weight, from 2.3% by weight to 4% by weight, from 2 , 4% by weight to 4% by weight, from 2.5% by weight to 4% by weight, from 2.6% by weight to 4% by weight, from 2.7% by weight to 4% by weight, from 2.8% by weight to 4% by weight, from 2.9% by weight to 4% by weight, from 3% by weight to 4% by weight, from 3.1% by weight to 4% by weight, from 3.2% by weight to 4% by weight, from 3.3% by weight to 4% by weight, from 3.4% by weight to 4% by weight, from 3.5% by weight to 4% by weight weight, from 3.6% by weight to 4% by weight, from 3.7% by weight to 4% by weight, from 3.8% by weight to 4% by weight, from 3.9% by weight to 4% % by weight , from 2% by weight to 5% by weight, from 2.1% by weight to 5% by weight, from 2.2% by weight to 5% by weight, from 2.3% by weight to 5% by weight , from 2.4% by weight to 5% by weight, from 2.5% by weight to 5% by weight, from 2.6% by weight to 5% by weight, from 2.7% by weight to 5% by weight, from 2.8% by weight to 5% by weight, from 2.9% by weight to 5% by weight, from 3% by weight to 5% by weight, from 3.1% by weight to 5% by weight, from 3.2% by weight to 5% by weight, from 3.3% by weight to 5% by weight, from 3.4% by weight to 5% by weight, from 3.5% by weight to 5% by weight, 3.6% by weight to 5% by weight, 3.7% by weight to 5% by weight, 3.8% by weight to 5% by weight, 3.9% by weight weight to 5% by weight, from 4% by weight to 5% by weight, from 4.1% by weight to 5% by weight, from 4.2% by weight to 5% by weight, from 4.3% to weight at 5% by weight, from 4.4% by weight to 5% by weight, from 4.5% by weight to 5% by weight, from 4.6% by weight to 5% by weight, from 4.7 % by weight to 5% by weight, from 4.8% by weight to 5% by weight, from 4.9% by weight to 5% by weight, from 2% by weight to 6% by weight, from 2.1 % by weight to 6% by weight, from 2.2% by weight to 6% by weight, from 2.3% by weight to 6% by weight, from 2.4% by weight to 6% by weight, from 2.5% by weight to 6% by weight, from 2.6% by weight to 6% by weight, 2.7% by weight to 6% by weight, from 2.8% by weight to 6% by weight, from 2.9% by weight to 6% by weight, from 3% by weight to 6% by weight, from 3.1% by weight to 6% by weight, from 3.2% by weight to 6% by weight, from 3.3% by weight to 6% by weight, from 3.4% by weight to 6% by weight, from 3, 5% by weight to 6% by weight, 3.6% by weight to 6% by weight, 3.7% by weight to 6% by weight, 3.8% by weight to 6% by weight, 3.9% by weight to 6% by weight, from 4% by weight to 6% by weight, from 4.1% by weight to 6% by weight, from 4.2% by weight to 6% by weight, 4.3% by weight to 6% by weight, from 4.4% by weight to 6% by weight, from 4.5% by weight to 6% by weight, from 4.6% by weight to 6% by weight , from 4.7% by weight to 6% by weight, from 4.8% by weight to 6% by weight, from 4.9% by weight to 6% by weight, from 5% by weight to 6% by weight , from 5.1% by weight to 6% by weight, from 5.2% by weight to 6% by weight, from 5.3% by weight to 6% by weight, from 5.4% by weight to 6% by weight, from 5.5% by weight to 6% by weight, from 5.6% by weight to 6% by weight, 5.7% by weight to 6% by weight, 5.8% by weight to 6% by weight, or 5.9% by weight to 6% by weight.
    [00035] In general, the Ca content in the various modalities of the MgZnCa alloy and of an implant based on the various modalities of the MgZnCa alloy, according to the present invention, can be any suitable amount. In one embodiment, the MgZnCa alloy has a Ca content that can be independently selected from the ranges of 0.0005% by weight to 0.0055% by weight, from 0.0005% by weight to 0.0005% by weight to 0.0205% by weight, from 0.0005% by weight to 0.0355% by weight, from 0.0005% by weight to 0.0505% by weight, from 0.0005% by weight to 0.0655% by weight, from 0.0005% by weight to 0.0805% by weight, from 0.0005% by weight to 0.0955% by weight, from 0.0005% by weight to 0.1105% by weight, from 0 .0005% by weight to 0.1255% by weight, from 0.0005% by weight to 0.1405% by weight, from 0.0005% by weight to 0.1555% by weight, to 0.0155% by weight , from 0.0005% by weight to 0.0305% by weight, from 0.0005% by weight to 0.0455% by weight, from 0.0005% by weight to 0.0605% by weight, from from 0.0005% by weight to 0.0755% by weight, from 0.0005% by weight to 0.0905% by weight, from 0.0005% by weight to 0.1055% by weight, from 0 .0005% by weight to 0.1205% by weight, from 0.0005% by weight to 0.13355% by weight, from 0.0005% by weight to 0.1505% by weight, of from 0.0005 % by weight to 0.1605% by weight, from 0.0 005% by weight to 0.1655% by weight, from 0.0005% by weight to 0.1705% by weight, from 0.0005% by weight to 0.1755% by weight, from 0.0005% by weight to 0.1805% by weight, from 0.0005% by weight to 0.1855% by weight, from 0.0005% by weight to 0.1905% by weight, from 0.0005% by weight to 0.1955% by weight, from 0.0005% by weight to 0.2005% by weight, from 0.0005% by weight to 0.2055% by weight, from 0.0005% by weight to 0.2105% by weight, from 0, 0005% by weight to 0.2155% by weight, from 0.0005% by weight to 0.2205% by weight, from 0.0005% by weight to 0.2255% by weight, from 0.0005% by weight to 0.2305% by weight, from 0.0005% by weight to 0.2355% by weight, from 0.0005% by weight to 0.2405% by weight, from 0.0005% by weight to 0.2455% by weight, from 0.0005% by weight to 0.2505% by weight, from 0.0005% by weight to 0.2555% by weight, from 0.0005% by weight to 0.2605% by weight, from 0, 0005% by weight to 0.2655% by weight, from 0.0005% by weight to 0.2705% by weight, from 0.0005% by weight to 0.2755% by weight, from 0.0005% by weight to 0.2805% by weight, from 0.0005% by weight to 0.2855% by weight, from 0.0005% by weight to 0.2905% by weight, from 0.0005% by weight to 0.2955% by weight, from 0.0005% by weight to 0.3005% by weight, from 0.0005% by weight to 0.3055% by weight, from 0.0005% by weight to 0.3105% by weight, from 0.0005% by weight to 0.3155% by weight, from 0.0005% by weight to 0.3205% by weight, from 0.0005% by weight to 0.3255% by weight, from 0 .0005% by weight to 0.3305% by weight, from 0.0005% by weight to 0.3355% by weight, from 0.0005% by weight to 0.3405% by weight, from 0.0005% by weight to 0.3455% by weight, from 0.0005% by weight to 0.3505% by weight, from 0.0005% by weight to 0.3555% by weight, from 0.0005% by weight to 0.3605% by weight, from 0.0005% by weight to 0.3655% by weight, from 0.0005% by weight to 0.3705% by weight, from 0.0005% by weight to 0.3755% by weight, from 0 .0005% by weight to 0.3805% by weight, from 0.0005% by weight to 0.3855% by weight, from 0.0005% by weight to 0.3905% by weight, from 0.0005% by weight to 0.3955% by weight, from 0.0005% by weight to 0.4005% by weight, from 0.0005% by weight to 0.4055% by weight, from 0.0005% by weight to 0.4105% by weight, from 0.0005% by weight to 0.4155% by weight, from 0.0005% by weight to 0.4205% by weight, from 0.0005% by weight to 0.4255% and m by weight, from 0.0005% by weight to 0.4305% by weight, from 0.0005% by weight to 0.4355% by weight, from 0.0005% by weight to 0.4405% by weight, from 0 .0005% by weight to 0.4455% by weight, from 0.0005% by weight to 0.4505% by weight, from 0.0005% by weight to 0.4555% by weight, from 0.0005% by weight to 0.4605% by weight, from 0.0005% by weight to 0.4655% by weight, from 0.0005% by weight to 0.4705% by weight, from 0.0005% by weight to 0.4755% by weight, from 0.0005% by weight to 0.4805% by weight, from 0.0005% by weight to 0.4855% by weight, from 0.0005% by weight to 0.4905% by weight, from 0 .0005% by weight to 0.4955% by weight, from 0.0005% by weight to 0.5005% by weight, from 0.0005% by weight to 0.505555% by weight, from 0.0005% by weight to 0.5105% by weight, from 0.0005% by weight to 0.5155% by weight, from 0.0005% by weight to 0.5205% by weight, from 0.0005% by weight to 0.5255% by weight, from 0.0005% by weight to 0.5305% by weight, from 0.0005% by weight to 0.5355% by weight, from 0.0005% by weight to 0.5405% by weight, from 0 .0005% by weight to 0.5455% by weight, from 0.0005% by weight to 0.5505% by weight, from 0.0005% by weight to 0.5555% by weight, from 0 .0005% by weight to 0.5605% by weight, from 0.0005% by weight to 0.5655% by weight, from 0.0005% by weight to 0.5705% by weight, from 0.0005% by weight to 0.5755% by weight, from 0.0005% by weight to 0.5805% by weight, from 0.0005% by weight to 0.5855% by weight, from 0.0005% by weight to 0.5905% by weight, from 0.0005% by weight to 0.5955% by weight, from 0.0005% by weight to 0.6005% by weight, from 0.0005% by weight to 0.6055% by weight, from 0 .0005% by weight to 0.6105% by weight, from 0.0005% by weight to 0.6155% by weight, from 0.0005% by weight to 0.6205% by weight, from 0.0005% by weight to 0.6255% by weight, from 0.0005% by weight to 0.6305% by weight, from 0.0005% by weight to 0.6355% by weight, from 0.0005% by weight to 0.6405% by weight, from 0.0005% by weight to 0.6455% by weight, from 0.0005% by weight to 0.6505% by weight, from 0.0005% by weight to 0.6555% by weight, from 0 .0005% by weight to 0.6605% by weight, from 0.0005% by weight to 0.6655% by weight, from 0.0005% by weight to 0.6705% by weight, from 0.0005% by weight to 0.6755% by weight, from 0.0005% by weight to 0.6805% by weight, from 0.0005% by weight to 0.6855% by weight, from 0.0005% by weight only 0.6905% by weight, from 0.0005% by weight to 0.6955% by weight, from 0.0005% by weight to 0.7005% by weight, from 0.0005% by weight at 0.7055 % by weight, from 0.0005% by weight to 0.7105% by weight, from 0.0005% by weight to 0.7155% by weight, from 0.0005% by weight to 0.7205% by weight, by 0.0005% by weight to 0.7255% by weight, from 0.0005% by weight to 0.7305% by weight, from 0.0005% by weight to 0.7355% by weight, from 0.0005% by weight. weight to 0.7405% by weight, from 0.0005% by weight to 0.7455% by weight, from 0.0005% by weight to 0.7505% by weight, from 0.0005% by weight to 0.7555 % by weight, from 0.0005% by weight to 0.7605% by weight, from 0.0005% by weight to 0.7655% by weight, from 0.0005% by weight to 0.7705% by weight, by 0.0005% by weight to 0.7755% by weight, from 0.0005% by weight to 0.7805% by weight, from 0.0005% by weight to 0.7855% by weight, from 0.0005% by weight. weight to 0.7905% by weight, from 0.0005% by weight to 0.7955% by weight, from 0.0005% by weight to 0.8005% by weight, from 0.0005% by weight to 0.8055 % by weight, from 0.0005% by weight to 0.8105% by weight, from 0.0005% by weight to 0.8155% by weight, from 0.0005% by weight to 0.8205% by weight, from 0.0005% by weight to 0.8255% by weight, from 0.0005% by weight to 0.8305% by weight, from 0.0005% by weight to 0.8355% by weight, from 0 .0005% by weight to 0.8405% by weight, from 0.0005% by weight to 0.8455% by weight, from 0.0005% by weight to 0.8505% by weight, from 0.0005% by weight to 0.8555% by weight, from 0.0005% by weight to 0.8605% by weight, from 0.0005% by weight to 0.8655% by weight, from 0.0005% by weight to 0.8705% by weight, from 0.0005% by weight to 0.8755% by weight, from 0.0005% by weight to 0.8805% by weight, from 0.0005% by weight to 0.8855% by weight, from 0 .0005% by weight to 0.8905% by weight, from 0.0005% by weight to 0.8955% by weight, from 0.0005% by weight to 0.9005% by weight, from 0.0005% by weight to 0.9055% by weight, from 0.0005% by weight to 0.9105% by weight, from 0.0005% by weight to 0.9155% by weight, from 0.0005% by weight to 0.9205% by weight, from 0.0005% by weight to 0.9255% by weight, from 0.0005% by weight to 0.9305% by weight, from 0.0005% by weight to 0.9355% by weight, from 0 .0005% by weight to 0.9405% by weight, from 0.0005% by weight to 0.9455% by weight, from 0.0005% by weight to 0.9505% by weight, from 0.0005% by weight to 0.9555% by weight, from 0.0005% by weight to 0.9605% by weight, from 0.0005% by weight to 0.9655% by weight, from 0.0005% by weight to 0.9705% by weight, from 0.0005% by weight to 0.9755% by weight, from 0.0005% by weight to 0.9805% by weight, from 0.0005% by weight to 0.9855 % by weight, from 0.0005% by weight to 0.9905% by weight, from 0.0005% by weight to 0.9955% by weight, and from 0.0005% by weight to 1% by weight.
    [00036] In general, the alloy compositions of the present invention are based on a single-phase material free of secondary phases that otherwise act as cathodic microgalvanic cells. In order to obtain the necessary level of purity of the MgZn and MgZnCa alloy modalities described herein, the acceptable amount of other elements in the alloy is limited.
    [00037] In one embodiment, the MgZn alloy contains less than 5 ppm of other total elements. In another embodiment, the MgZn alloy contains less than 2 ppm of other total elements. In yet another embodiment, the MgZn alloy contains less than 1 ppm of other total elements. In yet another embodiment, the MgZn alloy contains less than 0.5 ppm of other total elements.
    [00038] In one embodiment, the MgZnCa alloy, which has a plurality of nanodimensioned precipitates that are less noble than an MgZn alloy, contains less than 5 ppm of other total elements. In another embodiment, the MgZnCa alloy, which has a plurality of nanodimensioned precipitates that are less noble than an MgZn alloy, contains less than 2 ppm of other total elements. In yet another embodiment, the MgZnCa alloy, which has a plurality of nanodimensioned precipitates that are less noble than an MgZn alloy, contains less than 1 ppm of other total elements. In yet another embodiment, the MgZnCa alloy, which has a plurality of nanodimensioned precipitates that are less noble than an MgZn alloy, contains less than 0.5 ppm of other total elements.
    [00039] In one embodiment, the MgZnCa alloy, which has a plurality of nano-sized precipitates that are less noble than an MgZn alloy and a plurality of nano-sized precipitates that are more noble than an MgZn alloy, contains less than 5 ppm of other total elements. In another embodiment, the MgZnCa alloy, which has a plurality of nano-sized precipitates that are less noble than an MgZn alloy and a plurality of nano-sized precipitates that are more noble than an MgZn alloy, contains less than 2 ppm of other elements totals. In yet another embodiment, the MgZnCa alloy, which has a plurality of nano-sized precipitates that are less noble than an MgZn alloy and a plurality of nano-sized precipitates that are more noble than an MgZn alloy, contains less than 1 ppm of others total elements. In yet another embodiment, the MgZnCa alloy, which has a plurality of nanodimensioned precipitates that are less noble than an MgZn alloy and a plurality of nanodimensioned precipitates that are more noble than an MgZn alloy, contains less than 0.5 ppm of other total elements.
    [00040] In such modalities, the other elements include one or more among Fe, Cu, Ni, Co, Si, Mn, Al, Zr and P.
    [00041] In another embodiment, the MgZn alloy contains less than 5 ppm of Fe content. In another embodiment, the MgZn alloy contains less than 5 ppm of Si content. In another embodiment, the MgZn alloy contains less than 5 ppm of Mn content. In yet another embodiment, the MgZn alloy contains less than 2 ppm of Co content. In another embodiment, the MgZn alloy contains less than 2 ppm of Ni. In another embodiment, the MgZn alloy contains less than 0.1 ppm of Ni. In another embodiment, the MgZn alloy contains less than 2 ppm of Cu content. In yet another embodiment, the MgZn alloy contains less than 10 ppm Al content.
    [00042] In another embodiment, the MgZnCa alloy, which has a plurality of nanodimensioned precipitates that are less noble than an MgZn alloy, contains less than 5 ppm Fe content. In another embodiment, the MgZn alloy contains less than 5 ppm Si content. In another embodiment, the MgZnCa alloy, which has a plurality of nanodimensioned precipitates that are less noble than an MgZn alloy, contains less than 5 ppm Mn content. In yet another embodiment, the MgZnCa alloy, which has a plurality of nanodimensioned precipitates that are less noble than an MgZn alloy, contains less than 2 ppm of Co content. In another embodiment, the MgZnCa alloy, which has a plurality of nanodimensioned precipitates that are less noble than an MgZn alloy, contain less than 2 ppm of Ni. In another embodiment, the MgZnCa alloy, which has a plurality of nanodimensioned precipitates that are less noble than an MgZn alloy, contains less than 0.1 ppm of Ni. In another embodiment, the MgZnCa alloy, which has a plurality of nanodimensioned precipitates that are less noble than an MgZn alloy, contains less than 2 ppm Cu content. In yet another embodiment, the MgZnCa alloy, which has a plurality of nanodimensioned precipitates that are less noble than an MgZn alloy, contains less than 10 ppm Al content.
    [00043] In another embodiment, the MgZnCa alloy, which has a plurality of nano-sized precipitates that are less noble than an MgZn alloy and a plurality of nano-sized precipitates that are more noble than an MgZn alloy, contains less than 5 ppm of Fe content. In another embodiment, the MgZn alloy contains less than 5 ppm Si content. In another embodiment, the MgZnCa alloy, which has a plurality of nanodimensioned precipitates that are less noble than an MgZn alloy and a plurality of nanodimensioned precipitates that are more noble than an MgZn alloy, contain less than 5 ppm of Mn content. In yet another embodiment, the MgZnCa alloy, which has a plurality of nano-sized precipitates that are less noble than an MgZn alloy and a plurality of nano-sized precipitates that are more noble than an MgZn alloy, contains less than 2 ppm content. Co. In another embodiment, the MgZnCa alloy, which has a plurality of nano-sized precipitates that are less noble than an MgZn alloy and a plurality of nano-sized precipitates that are more noble than an MgZn alloy, contains less than 2 ppm of Ni. In another embodiment, the MgZnCa alloy, which has a plurality of nano-sized precipitates that are less noble than an MgZn alloy and a plurality of nano-sized precipitates that are more noble than an MgZn alloy, contains less than 0.1 ppm of Ni. In another embodiment, the MgZnCa alloy, which has a plurality of nano-sized precipitates that are less noble than an MgZn alloy and a plurality of nano-sized precipitates that are more noble than an MgZn alloy, contains less than 2 ppm content. Ass. In yet another embodiment, the MgZnCa alloy, which has a plurality of nano-sized precipitates that are less noble than an MgZn alloy and a plurality of nano-sized precipitates that are more noble than an MgZn alloy, contains less than 10 ppm content. Al.
    [00044] The level of impurity is maintained at such levels to control the rate of corrosion once an implant, based on such alloys, is placed in the body. It is necessary to control the corrosion rate so that the implant has sufficient strength over a period of time to allow it to cure and thus not interfere with the healing process. Although the degradation by-products of the magnesium alloys of the present invention are non-toxic, as the metal corrodes, the pH near the implant increases to a basic pH. Similarly, the hydrogen gas produced during the corrosion process needs to be eliminated. In the case of endovascular implants, these concerns are insignificant since the constant blood flow over the implant removes hydrogen gas and other degradation by-products.
    [00045] In general, the content of rare earths in the various modalities of the MgZn alloy, the MgZnCa alloy and the MgZn alloy, of the MgZnCa alloy compositions used in an implant, according to the present invention is limited . In such modalities, the rare earth elements include Sc, Y, the lanthanide elements, atomic numbers in the range 57 to 71 and the actnid elements, atomic numbers in the range 89 to 103. In one mode, the rare earth content is less than 10 ppm. In another modality, the content of rare earths is less than 5 ppm. In some embodiments, the rare earth content is less than 1 ppm, less than 0.5 ppm, less than 0.1 ppm or less than 0.05 ppm.
    [00046] The mechanical properties of ultrapure magnesium are enhanced by hardening a solid solution with high purity zinc without affecting the monophasic nature of the alloy. A finely ground microstructure can be achieved through rigorous and stabilized plastic deformation with secondary phases that are less noble than the magnesium matrix. For example, the less noble phase of Mg6Zn3Ca2 can be obtained through small additions of calcium with high purity content and adequate heat treatment. If necessary, the rate of degradation can be accelerated, while maintaining a uniform corrosion profile, by means of an aging heat treatment below 250 ° C, which forms fine metastable MgZn precipitates.
    [00047] The implants produced from the compositions described here have advantageous physical properties, which include high yield stress, high tensile strength and elongation at break. In some embodiments, each alloy has a yield strength of at least 200 MPa. In other modalities, each alloy has a yield stress of at least 220 MPa, at least 240 MPa, at least 250 MPa, at least 260 MPa, at least 280 MPa, at least 300 MPa, at least 320 MPa, while minus 340 MPa, at least 360 MPa or at least 380 MPa. In some embodiments, each alloy has a tensile strength of at least 250 MPa. In other modalities, each alloy has a tensile strength of at least 260 MPa, at least 280 MPa, at least 300 MPa, at least 320 MPa, at least 340 MPa, at least 360 MPa or at least 380 MPa. In some modalities, each alloy has at least 15% elongation at break. In other modalities, each league has at least 16%, at least 17%, at least 18%, at least 19%, at least 20%, at least 21%, at least 22%, at least 23%, at least 24 %, at least 25%, at least 26%, at least 27%, at least 28%, at least 29%, or at least 30% elongation at break.
    [00048] Implants according to the exemplary embodiments of the present invention also have advantageous chemical properties in vitro and in vivo. In some embodiments, each alloy has an in vitro degradation rate of less than 0.5 mg / cm2 day as measured in a simulated body fluid. In other embodiments, each alloy has an in vitro degradation rate of less than 0.05 mg / cm2day, less than 0.1 mg / cm2day, less than 0.15 mg / cm2day, less than 0.2 mg / cm2day, less 0.25 mg / cm2 day, less than 0.3 mg / cm2 day, less than 0.35 mg / cm2 day, less than 0.4 mg / cm2 day or less than 0.45 mg / cm2 day, as measured in a body fluid simulated.
    [00049] Medical devices implantable based on the compositions described herein can be manufactured for a variety of medical / clinical applications, including replacing an absent biological structure, sustaining a damaged biological structure or accentuating an existing biological structure. The composition of the implants and / or the surfaces of the implants that come into contact with the body / body tissues may vary depending on the particular application under consideration. Surgical implants can be manufactured for medical / clinical applications in the field of orthopedics, neurosurgery, among others. Non-limiting examples of surgical implants include: neurosurgical implants, for example, bypass and hydrocephalic components; intracranial aneurysm loops; bone and joint replacements, for example, total or partial thigh joint prostheses and total knee joint prostheses; osteosynthesis and spinal devices, for example, metal bone screws, metal bone plates, medullary pins, metallic skeletal pins and wires and total intervertebral spinal disc prostheses; oral maxillofacial surgery implants; and spinal and pelvic systems like the Universal Spine System, Harrington System and conventional systems. Consequently, surgical implants that can be manufactured based on the compositions described herein can include a wide range of products with different compositions as described herein, structural complexity and medical / clinical applications. Thus, implants for use in accordance with the exemplary embodiments of the present invention can vary in size, shape and other physical and chemical characteristics that depend on the context of use.
    [00050] In some modalities, the implant is an orthopedic implant. In such embodiments, the orthopedic implant comprises one or more of the following: a pin, a thread, a clamp, a plate, a rod, a tack, a screw, a locking screw and an intramedullary pin, an anchor, a pin, a plug, a stake, a sleeve, a mesh, a transconector, a nut, a shaped body, spinal cage, a wire, a Kirschner wire, a woven structure, a claw, a splint, a frame, a foam and a beehive structure. In some other embodiments, the implant has a lower rate of degradation compared to magnesium alloy implants that contain microgalvanic impurities.
    [00051] In other modalities, the implant is a non-orthopedic implant. In such modalities, the non-orthopedic implant includes a cardiovascular stent, a neural stent, or a vertebroplasty stent.
    [00052] The corrosion rate of magnesium depends heavily on its purity. In a 4% sodium chloride water solution, a 99.9% purity magnesium corrosion rate is supposed to be hundreds of times higher than for 99.99% purity magnesium.
    [00053] In vitro degradation tests in simulated body fluid (SBF) show that uniform degradation with extremely low degradation rate can be obtained when using such ultrapure magnesium. However, ultrapure magnesium has unsatisfactory mechanical properties compared to alloys such as WE43. It was found that this limitation can be overcome by hardening the alloy. The hardening of the alloy can be obtained by refining the granular microstructure with the use of rigorous plastic deformation (ECAP, extrusion, etc.). In addition to obtaining a more satisfactory level of resistance, it was also found that the finely crushed microstructure avoids mechanical anisotropy (difference in strength between tension and compression).
    [00054] It was also found that the hardening of the magnesium matrix could be obtained by means of a solid solution with a highly pure alloying element such as zinc. The phase diagram for Mg-Zn shows a maximum solubility of 6.2% by weight of Zn at eutectic temperature. After the formation of magnesium alloy with, for example, 5% by weight of Zn, the material could be homogenized by a two-stage solution heat treatment, with a first temperature below and a second temperature above the eutectic temperature. The resulting single-phase alloy has been found to exhibit very uniform and slow degradation.
    [00055] In one aspect, the present invention provides a method of producing an alloy according to the modalities described herein. In one embodiment, the method comprises: (a) melting an alloy that contains (i) ultrapure magnesium that has a purity of at least 99.997% by weight and that has less than 0.001% by weight of one or more other elements; and (ii) from 2.0 to 6% by weight of zinc, which has a purity of at least 99.999% by weight, said casting being carried out in an inert atmosphere and in an inert reaction vessel; (b) heat the molten alloy at two different temperatures, the first temperature being below the eutectic temperature of Mg-Zn and the second temperature being above the eutectic temperature of the ternary Mg-Zn-Ca system to form, in this way, a single-phase MgZn alloy containing from 2.0% by weight of Zn to 6% by weight of Zn, which has less than 0.001% by weight of one or more other elements in which the remainder is Mg; and (c) extruding the alloy in a desired shape.
    [00056] In some embodiments, the method of producing an alloy according to the present invention comprises: (a) melting an alloy containing (i) ultrapure magnesium which has a purity of at least 99.997% by weight and which has less than 0.001% by weight of one or more other elements; (ii) from 3.0% to 6% by weight of zinc which has a purity of at least 99.999% by weight; and (iii) from 0.02% by weight to 1.0% by weight of calcium metal, which has a purity of at least 99.9% by weight, and said smelting is carried out in an inert atmosphere and in a inert reaction vessel; (b) heat the molten alloy at two different temperatures, the first temperature being below the eutectic temperature of Mg-Zn and the second temperature being above the eutectic temperature of the ternary Mg-Zn-Ca system to form, in this way, an MgZnCa alloy containing from 3.0% by weight of Zn to 6% by weight of Zn; a calcium content in the range of 0.0005% by weight to 1.0% by weight, which is less than 0.001% by weight of one or more other elements in which the remainder is Mg, (c) extruding the alloy in a desired format; and (d) heating the shaped alloy to at least 140 ° C to form more noble nanodimensioned precipitates dispersed over an MgZnCa alloy. In an additional embodiment, the method comprises heating to at least 230 ° C to form more noble precipitates dispersed over an MgZn alloy.
    [00057] Without sticking to any theory, it is believed that it is advantageous that the grain contours in the stable finely crushed microstructure of the alloy are affixed. The display could be achieved by fine precipitates that are less noble than the magnesium matrix and, as a consequence, do not deteriorate the material's degradation performance. Mg6Zn3Ca2 is one of the few phases that is electrochemically less noble than pure magnesium. With the addition of 0.25% by weight of Ca, such finely dispersed precipitates can be created by means of an aging heat treatment (after the initial solution heat treatment). If the rate of degradation of the alloy is very low and needs to be accelerated, very fine metastable MgZn precipitates can be formed by applying an aging heat treatment at temperatures below 250 ° C. With the increase in size, these precipitates begin to act as cathodic microgalvanic elements and accelerate corrosion in a controllable manner.
    [00058] Magnesium alloys in the exemplary embodiments described above have properties specifically favorable for processing and for the purpose for which they are intended compared to traditional magnesium alloys: the ductility of magnesium alloys is high in large proportions. For the purposes of the present disclosure, the term "ductility" (or toughness, deformation capacity) refers to the ability of a metallic material to undergo permanent deformation under sufficiently high mechanical loads before cracking occurs. This capacity is of great importance for many construction parts due to the fact that only a ductile material is capable of dissipating the peaks of local mechanical stress when undergoing permanent deformation without cracking and with simultaneous cold solidification. This aspect, in particular, makes it particularly advantageous to use the magnesium alloys of the invention as a material, for example, for biodegradable implants, in particular, biodegradable implants for bone fixation. With a given material, ductility depends on the temperature, the stress rate, the character of multiple geometric axes of the state of active mechanical stress and the environment. Characteristic ductility values include, for example, elongation at break and attenuation, resistance to notched impact and resistance to fracture as described here elsewhere.
    [00059] It will be appreciated by those skilled in the art that changes could be made to the exemplary modalities shown and described above without leaving the broad inventive concept of them. It is understood, therefore, that this invention is not limited to the exemplary embodiments shown and described, but is intended to cover modifications within the spirit and scope of the present invention as defined by the claims. For example, specific features of the exemplary embodiments may or may not be part of the claimed invention and features of the disclosed embodiments may be combined. Unless specifically described here, the terms "one", "one", "o" and "a" are not limited to one element, but should instead be read with the meaning of "at least one".
    [00060] It is understood that at least some of the descriptions of the invention have been simplified to focus on elements that are relevant to a clear understanding of the invention, and that other elements that are known to those skilled in the art have been eliminated, for the sake of clarity, may also comprise a portion of the invention. However, due to the fact that such elements are well known in the art and because they do not necessarily facilitate a better understanding of the invention, a description of such elements is not provided here.
    [00061] Additionally, to the extent that the method does not depend on the particular order of steps presented here, the particular order of steps should not be considered a limitation of the claims. Claims directed to the method of the present invention should not be limited to the performance of the steps in the written order and one skilled in the art can immediately understand that the steps can be varied and still remain in the spirit and scope of the present invention.
    权利要求:
    Claims (17)
    [0001]
    1. MgZnCa alloy composition, characterized by the fact that it contains a magnesium matrix and nanodimensioned precipitates, the nanodimensioned precipitates being less noble than the magnesium matrix, the alloy having a Zn content in the range of 3.0% by weight to 6% by weight and a calcium content in the range of 0.0005% by weight to 1.0% by weight, less than 0.001% by weight of one or more other elements which are Fe, Cu, Ni, Co, Si , Mn, Al, Zr, P, Sc, Y, lanthanide elements with atomic numbers ranging from 57 to 71 and the actinide elements with atomic numbers ranging from 89 to 103 and with the rest of the alloy being Mg, and in which the Mg has a purity of at least 99.997% by weight, Zn has a purity of at least 99.999% by weight, and Ca has a purity of at least 99.9% by weight.
    [0002]
    2. MgZnCa alloy composition according to claim 1, characterized by the fact that the alloy contains less than 5 ppm of one or more of other elements which are Fe, Cu, Ni, Co, Si, Mn, Al, Zr , P, Sc, Y, lanthanide elements with atomic numbers ranging from 57 to 71 and actinide elements with atomic numbers ranging from 89 to 103.
    [0003]
    3. MgZnCa alloy composition according to claim 2, characterized by the fact that the alloy contains less than 2 ppm of one or more of other elements which are Fe, Cu, Ni, Co, Si, Mn, Al, Zr , P, Sc, Y, lanthanide elements with atomic numbers ranging from 57 to 71 and actinide elements with atomic numbers ranging from 89 to 103.
    [0004]
    4. MgZnCa alloy composition according to claim 2, characterized by the fact that the alloy contains less than 1 ppm of one or more of other elements which are Fe, Cu, Ni, Co, Si, Mn, Al, Zr , P, Sc, Y, lanthanide elements with atomic numbers ranging from 57 to 71 and actinide elements with atomic numbers ranging from 89 to 103.
    [0005]
    MgZnCa alloy composition according to claim 2, characterized by the fact that the alloy contains less than 0.5 ppm of one or more of other elements which are Fe, Cu, Ni, Co, Si, Mn, Al , Zr, P, Sc, Y, lanthanide elements with atomic numbers ranging from 57 to 71 and actinide elements with atomic numbers ranging from 89 to 103.
    [0006]
    MgZnCa alloy composition according to any one of claims 1 to 5, characterized in that the alloy contains less than 0.1 ppm Ni.
    [0007]
    MgZnCa alloy composition according to any one of claims 1 to 6, characterized in that the alloy has a grain size of less than 10 μm.
    [0008]
    MgZnCa alloy composition according to any one of claims 1 to 7, characterized in that the alloy has a yield stress of at least 200 MPa.
    [0009]
    MgZnCa alloy composition according to any one of claims 1 to 8, characterized in that the alloy has a tensile strength of at least 250 MPa.
    [0010]
    10. MgZnCa alloy composition according to any one of claims 1 to 9, characterized in that the alloy has at least 15% elongation at break.
    [0011]
    11. Implant, characterized by the fact that it comprises the alloy as defined in any one of claims 1 to 10.
    [0012]
    12. Implant according to claim 11, characterized by the fact that the implant has an in vitro degradation rate of less than 0.5 mg / cm2 per day as measured in a simulated body fluid.
    [0013]
    13. Implant according to claim 11 or 12, characterized by the fact that the implant is an orthopedic implant.
    [0014]
    14. Implant according to claim 13, characterized by the fact that the orthopedic implant comprises one or more of the following: a pin, a thread, a clamp, a plate, a rod, a tack, a screw, a locking screw and an intramedullary pin, an anchor, a peg, a plug, a peg, a sleeve, a mesh, a transconector, a nut, a shaped body, spinal cage, a thread, a Kirschner thread, a woven structure, a claw, a splint, a frame, a foam and a honeycomb structure.
    [0015]
    15. Implant according to claim 11 or 12, characterized by the fact that the implant is a non-orthopedic implant.
    [0016]
    16. Implant according to claim 15, characterized by the fact that the non-orthopedic implant comprises a cardiovascular stent, a neural stent or a vertebroplasty stent.
    [0017]
    17. Method of producing an MgZnCa alloy composition as defined in any one of claims 1 to 10, characterized in that it comprises the steps of: (a) melting a mixture containing (i) ultrapure magnesium that has a purity at least 99.997% by weight and having less than 0.001% by weight of one or more other elements; (ii) from 3.0% by weight to 6.0% by weight of zinc which has a purity of at least 99.999% by weight; and (iii) from 0.0005% by weight to 1.0% by weight of calcium metal, which has a purity of at least 99.9% by weight, and said smelting is carried out in an inert atmosphere and in a inert reaction vessel; (b) heat the molten alloy at two different temperatures, the first temperature being below the eutectic temperature of Mg-Zn and the second temperature being above the eutectic temperature of the ternary Mg-Zn-Ca system to form, in this way, an MgZnCa alloy containing from 3.0% by weight of Zn to 6% by weight of Zn, and a calcium content in the range of 0.0005% by weight to 1.0% by weight, and which has less than 0.001% by weight of one or more other elements, with the remainder being Mg, and (c) extruding the alloy in a desired shape.
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    同族专利:
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    法律状态:
    2018-11-21| B06F| Objections, documents and/or translations needed after an examination request according [chapter 6.6 patent gazette]|
    2019-07-09| B07A| Technical examination (opinion): publication of technical examination (opinion) [chapter 7.1 patent gazette]|
    2020-02-27| B07A| Technical examination (opinion): publication of technical examination (opinion) [chapter 7.1 patent gazette]|
    2021-01-12| B09A| Decision: intention to grant [chapter 9.1 patent gazette]|
    2021-03-02| B16A| Patent or certificate of addition of invention granted|Free format text: PRAZO DE VALIDADE: 20 (VINTE) ANOS CONTADOS A PARTIR DE 29/08/2013, OBSERVADAS AS CONDICOES LEGAIS. |
    优先权:
    申请号 | 申请日 | 专利标题
    US201261695621P| true| 2012-08-31|2012-08-31|
    US61/695,621|2012-08-31|
    US13/827,008|2013-03-14|
    US13/827,008|US9469889B2|2012-08-31|2013-03-14|Ultrapure magnesium alloy with adjustable degradation rate|
    PCT/US2013/057294|WO2014036262A1|2012-08-31|2013-08-29|Ultrapure magnesium alloy with adjustable degradation rate|
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