Medical biological rare earth magnesium alloy material as well as preparation method and application thereof

Abstract

The invention provides a medical biological rare earth magnesium alloy material. The medical biological rare earth magnesium alloy material comprises magnesium, gadolinium, zinc, zirconium, dysprosium and scandium. According to the rare earth magnesium alloy material provided by the invention, different contents of rare earth gadolinium, dysprosium, scandium, zinc and zirconium are added to improve the casting performance and the processing performance of a melt, and the alloy structure is improved through solid solution strengthening, dispersion strengthening and grain refinement effects, so that the strength and the ductility are improved; meanwhile, the selection design of the alloy elements strictly conforms to the limitation of biotoxicity, and the biological activity of the alloy elements can not be influenced, so that excellent mechanical properties and processability are obtained while good biocompatibility is kept, and the alloy elements play roles in accelerating osteogenesis and promoting bone tissue growth while playing a fixing role; the non-toxicity, the degradability and the high therapeutic property are really realized.

Description

Technical Field

[0001] The present invention belongs to the technical field of medical biological materials, and in particular relates to a medical biological rare earth magnesium alloy material and a preparation method and application thereof. Background Art

[0002] In recent years, new medical materials and products have developed rapidly, among which bone implant materials have been widely used in surgical medical materials, and degradable bone implant materials have become a hot topic of research. The strength of consumables such as polymers, ceramics or bioactive glass for bearing is poor, which is very different from the density and elastic modulus of human bones. Metal materials are the most widely used orthopedic biomaterials and are currently the dominant materials in this field. Titanium alloys and stainless steel are non-degradable in the human body, prone to inflammation and rejection during service, and require secondary surgery to remove after the recovery period, which increases the pain and economic burden of patients. Magnesium and magnesium alloys can corrode and degrade in the human body, and are closest to the density and elastic modulus of human bones, which can avoid stress shielding. Despite this, the mechanical properties of the commonly used traditional magnesium alloy materials in the market are insufficient, the processing performance cannot meet the product preparation requirements, and the biosafety and compatibility are relatively poor. They are not suitable as medical bone implant materials and processed into related products.

[0003] Therefore, it is an urgent problem to provide a medical magnesium alloy material with excellent mechanical properties, good processing performance, non-toxicity and good biocompatibility. Summary of the invention

[0004] In view of this, the technical problem to be solved by the present invention is to provide a medical biological rare earth magnesium alloy material and a preparation method and application thereof. The medical biological rare earth magnesium alloy material provided by the present invention has excellent mechanical properties, excellent processing performance, non-toxicity and good biocompatibility.

[0005] The invention provides a medical biological rare earth magnesium alloy material, comprising magnesium, gadolinium, zinc, zirconium, dysprosium and scandium elements.

[0006] Preferably, the medical biological rare earth magnesium alloy material comprises: 0.5-2.5wt.% Gd, 0.5-2.0wt.% Zn, 0.1-1.0wt.% Zr, 0.1-0.5wt.% Dy, 0.1-0.5wt.% Sc, and the rest are Mg and unavoidable impurity elements.

[0007] Preferably, among the impurity elements, Fe≤0.005wt.%, Cu≤0.0005wt.%, Si≤0.005wt.%, and Ni≤0.0005wt.%.

[0008] Preferably, the medical biological rare earth magnesium alloy material comprises MgZn having a layered structure.0.35 G 0.89 MgZn 8.37 G 11.32 phase and Mg3Zn3Gd phase with face-centered cubic structure;

[0009] Preferably, the Mg element, the Gd element and the Zn element also form an intermetallic compound with a size of 3 to 17 μm; further preferably, the intermetallic compound is in a coherent or semi-coherent relationship with the medical biological rare earth magnesium alloy material matrix.

[0010] The present invention also provides a method for preparing the above-mentioned medical biological rare earth magnesium alloy material, comprising the following steps:

[0011] The gadolinium element, the dysprosium element, the scandium element and the zirconium element are mixed with magnesium and zinc using an intermediate alloy and smelted into an alloy ingot, which is then subjected to a solid solution treatment, hot extrusion and aging treatment to obtain a rare earth magnesium alloy material.

[0012] Preferably, the mixed smelting into alloy ingots comprises the following steps:

[0013] 1) Under protective atmosphere conditions, heating a magnesium ingot until it is melted to obtain a magnesium melt;

[0014] 2) adding zinc particles to the magnesium melt after heating until the magnesium melt is melted;

[0015] 3) heating again, adding magnesium-gadolinium master alloy, magnesium-dysprosium master alloy, and magnesium-scandium master alloy, heating and melting;

[0016] 4) Continue to increase the temperature and add magnesium-zirconium master alloy to obtain an alloy melt;

[0017] 5) refining the alloy melt to obtain a refined melt;

[0018] 6) The refined melt is heated and allowed to stand for a period of time before being cast into an ingot.

[0019] Preferably, in step 1), the protective atmosphere condition is a mixed protective gas of SF6 and CO2 in a volume ratio of 1: (100-120);

[0020] In step 2), the heating temperature is 710-810°C;

[0021] In step 3), the temperature of the re-heating is 686-786° C.; in the magnesium-gadolinium master alloy, the mass ratio of magnesium to gadolinium is 7:3; in the magnesium-dysprosium master alloy, the mass ratio of magnesium to dysprosium is 7:3; in the magnesium-scandium master alloy, the mass ratio of magnesium to scandium is 7:3;

[0022] In step 4), the temperature of the continued heating is 718-818° C.; the mass ratio of magnesium to zirconium in the magnesium-zirconium master alloy is 7:3;

[0023] In step 5), the refining temperature is 678-778°C and the time is 0.5-5 min; a refining agent is added during the refining process, and the refining agent includes: 42-45% magnesium chloride, 28-30% potassium chloride, 5.5-6.5% sodium chloride, 6.5-7.5% calcium fluoride, 13-15% magnesium oxide, and the rest is water-insoluble matter; the amount of the refining agent added is 0.5%-3%;

[0024] In step 6), the temperature of the heating and standing is 696-796°C for 15-25 minutes; the temperature of the casting is 668-768°C.

[0025] Preferably, the solution treatment comprises: placing the alloy ingot in a heat treatment furnace, heating it to 460-560° C. in a vacuum furnace, keeping the temperature for 6-10 hours, and then placing it in air to cool to room temperature;

[0026] The temperature of the hot extrusion is 320-380°C, the extrusion speed is set between 0.02-1m / s, and the extrusion ratio is 8:1-13:1;

[0027] The aging treatment is carried out at a temperature of 175 to 200° C. and for a time of 20 to 40 hours.

[0028] The present invention also provides an application of the rare earth magnesium alloy material in preparing medical implant materials.

[0029] Compared with the prior art, the present invention provides a medical biological rare earth magnesium alloy material, including magnesium, gadolinium, zinc, zirconium, dysprosium and scandium elements. The rare earth magnesium alloy material provided by the present invention improves melt casting performance and processing performance by adding different contents of rare earth gadolinium, dysprosium, scandium, zinc and zirconium elements, and improves the alloy structure through solid solution strengthening, dispersion strengthening and grain refinement, and improves strength and ductility. At the same time, the selection and design of alloy elements strictly abide by biological toxicity restrictions and can not affect its biological activity, thereby obtaining excellent mechanical properties and processing properties while retaining good biocompatibility, so that it can play a role in accelerating osteogenesis and promoting bone tissue growth while playing a fixing role, and truly achieving non-toxic, degradable and highly therapeutic properties. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] Figure 1 The metallographic photographs of the alloy prepared in Example 1 at different stages, wherein: Figure 1 (a) is a metallographic photograph of the cast alloy prepared in Example 1; Figure 1 (b) is a metallographic photograph of the solution treated alloy prepared in Example 1; Figure 1 (c) is a metallographic photograph of the hot extruded alloy prepared in Example 1; Figure 1 (d) is a metallographic photograph of the aging treated alloy prepared in Example 1;

[0031] Figure 2 Scanning electron microscope photos of the alloy prepared in Example 1 at different stages, wherein: Figure 1 (a) is a scanning electron microscope photograph of the cast alloy prepared in Example 1; Figure 2 (b) is a scanning electron microscope photograph of the solution treated alloy prepared in Example 1; Figure 2 (c) is a scanning electron microscope photograph of the hot extruded alloy prepared in Example 1; Figure 2 (d) is a scanning electron microscope photograph of the aging treated alloy prepared in Example 1;

[0032] Figure 3 This is a typical scanning electron microscope photograph of the second phase in the aging treated alloy prepared in Example 1;

[0033] Figure 4 These are photos of different cell morphologies, among which: Figure 4 (a) is a photo of the elongated healthy adherent 3T3 cells in the extract of 100% immersion in the aging treated alloy prepared in Example 1; Figure 4 (b) is a photo of the round, non-adherent, unhealthy 3T3 cell morphology;

[0034] Figure 5 The scanning electron microscope photo and energy spectrum of hydroxyapatite generated on the surface of the aging treated alloy sample prepared in Example 1 after being immersed in simulated body fluid for 7 days, wherein: Figure 5 (a) is a scanning electron microscope photograph of hydroxyapatite formed on the surface of the aged alloy sample prepared in Example 1 after being immersed in simulated body fluid for 7 days; Figure 5 (b) is the energy spectrum of hydroxyapatite generated on the surface of the aged alloy sample prepared in Example 1 after being immersed in simulated body fluid for 7 days. DETAILED DESCRIPTION

[0035] The invention provides a medical biological rare earth magnesium alloy material, comprising magnesium, gadolinium, zinc, zirconium, dysprosium and scandium elements.

[0036] Specifically, the medical biological rare earth magnesium alloy material provided by the present invention includes: 0.5-2.5wt.% Gd, 0.5-2.0wt.% Zn, 0.1-1.0wt.% Zr, 0.1-0.5wt.% Dy, 0.1-0.5wt.% Sc, and the rest are Mg and unavoidable impurity elements.

[0037] Among them, the medical biological rare earth magnesium alloy material provided by the present invention includes 0.5-2.5wt.% Gd, which can be 0.5wt.%, 0.75wt.%, 1wt.%, 1.25wt.%, 1.5wt.%, 1.75wt.%, 2wt.%, 2.25wt.%, 2.5wt.%, or any value between 0.5 and 2.5wt.%.

[0038] The medical biological rare earth magnesium alloy material provided by the present invention also includes 0.5-2.0wt.% Zn, which can be 0.5wt.%, 0.75wt.%, 1wt.%, 1.25wt.%, 1.5wt.%, 1.75wt.%, 2wt.%, or any value between 0.5 and 2wt.%.

[0039] The medical biological rare earth magnesium alloy material provided by the present invention also includes 0.1-1.0wt.% Zr, which can be 0.1wt.%, 0.2wt.%, 0.3wt.%, 0.4wt.%, 0.5wt.%, 0.6wt.%, 0.7wt.%, 0.8wt.%, 0.9wt.%, 1wt.%, or any value between 0.1 and 1.0wt.%.

[0040] The medical biological rare earth magnesium alloy material provided by the present invention also includes 0.1-0.5wt.% Dy, which can be 0.1wt.%, 0.15wt.%, 0.2wt.%, 0.25wt.%, 0.3wt.%, 0.35wt.%, 0.4wt.%, 0.45wt.%, 0.5wt.%, or any value between 0.1 and 0.5wt.%.

[0041] The medical biological rare earth magnesium alloy material provided by the present invention also includes 0.1-0.5wt.% Sc, which can be 0.1wt.%, 0.15wt.%, 0.2wt.%, 0.25wt.%, 0.3wt.%, 0.35wt.%, 0.4wt.%, 0.45wt.%, 0.5wt.%, or any value between 0.1 and 0.5wt.%.

[0042] In addition to the above elements, the medical biological rare earth magnesium alloy material provided by the present invention also includes Mg and inevitable impurity elements.

[0043] In the present invention, among the impurity elements, Fe≤0.005wt.%, Cu≤0.0005wt.%, Si≤0.005wt.%, and Ni≤0.0005wt.%.

[0044] The medical biological rare earth magnesium alloy material comprises MgZn having a layered structure 0.35 G 0.89 MgZn8.37 G 11.32 phase and Mg3Zn3Gd phase with face-centered cubic structure;

[0045] Preferably, the Mg element, the Gd element and the Zn element also form an intermetallic compound with a size of 3 to 17 μm;

[0046] Further preferably, the intermetallic compound is in a coherent or semi-coherent relationship with the medical biological rare earth magnesium alloy material matrix, the precipitated phase has high strength and good plasticity, and is finely dispersed and continuously or discontinuously distributed at the grain boundaries, which plays a dual role in both improving the strength and improving the plasticity of the alloy.

[0047] The present invention increases the Gd-containing precipitate phase, i.e., MgZn 0.35 G 0.89、 MgZn 8.37 G 11.32 The nucleation density of the Mg3Zn3Gd phase and the precipitation efficiency are improved, and the improvement effect of the alloying elements and the precipitates on the mechanical properties, processing properties, biosafety and biocompatibility of biomedical rare earth magnesium alloys is enhanced.

[0048] The biomedical rare earth magnesium alloy material provided by the present invention is non-sensitizing to cells and has a bactericidal function. It can further treat osteoporosis by promoting cell growth and proliferation and degrading to generate hydroxyapatite in body fluids (the magnesium alloy degrades in body fluids to generate hydroxyapatite, the main component of human bone, which can treat osteoporosis. The specification drawings Figure 5 To generate hydroxyapatite), increase bone density, strengthen bones and reduce the risk of further fractures.

[0049] First, rare earth elements gadolinium, dysprosium, scandium and MgZn 0.35 G 0.89、 MgZn 8.37 G 11.32 The gadolinium element in the Mg3Zn3Gd phase has active chemical properties and can synergistically interact with the impurity elements in the magnesium alloy, and convert harmful metal inclusions in the solution into intermetallic compounds and remove them, thereby improving the mechanical properties and degradation properties of biomedical magnesium alloys.

[0050] Second, rare earth elements gadolinium, dysprosium, scandium and MgZn 0.35 G 0.89、 MgZn 8.37 G 11.32 The addition of gadolinium to the Mg3Zn3Gd phase can synergistically reduce the oxidation tendency of biomedical magnesium alloys in liquid and solid states, and improve their casting and processing properties.

[0051] Third, rare earth elements gadolinium, dysprosium, scandium and MgZn0.35 G 0.89、 MgZn 8.37 G 11.32 The enrichment of gadolinium in the Mg3Zn3Gd phase synergizes with the enrichment at the front of the solid-liquid interface to cause supercooling of the components. New nucleation zones are formed in the supercooling zone to form fine equiaxed crystals, which hinder the growth of α-Mg grains, promote grain refinement, and hinder recrystallization and grain growth during hot extrusion.

[0052] Fourth, rare earth elements gadolinium, dysprosium, scandium and MgZn 0.35 G 0.89、 MgZn 8.37 G 11.32 The atomic mass of gadolinium in the Mg3Zn3Gd phase is much greater than that of magnesium atoms, and its atomic radius is also greater than that of magnesium atoms. The rare earth elements gadolinium, dysprosium, scandium and MgZn 0.35 G 0.89、 MgZn 8.37 G 11.32 The atoms of the gadolinium element in the Mg3Zn3Gd phase have a small diffusion coefficient in magnesium, which can synergistically slow down the atomic diffusion rate and hinder dislocation movement, thereby strengthening the magnesium alloy matrix and improving the strength and ductility of biomedical magnesium alloys.

[0053] Fifth, the binding force of rare earth elements gadolinium, zinc and zirconium is significantly stronger than that of dysprosium and scandium, forming fine intermetallic compound particles, namely MgZn 0.35 G 0.89 MgZn 8.37 G 11.32 The second phase of Mg3Zn3Gd is dispersed at the grain boundaries and within the grains, which can pin the grain boundaries, inhibit grain boundary sliding, and hinder dislocation movement, thereby strengthening the magnesium alloy matrix and improving the strength and ductility of biomedical magnesium alloys.

[0054] Sixth, rare earth elements gadolinium, dysprosium, scandium and MgZn 0.35 G 0.89、 MgZn 8.37 G 11.32 The gadolinium element in the Mg3Zn3Gd phase has a suitable toxic concentration. At the same time, the highly soluble Gd, Dy and Sc show outstanding biofriendliness, are easily soluble in human body fluids, and are metabolized by the human body and excreted from the body with sweat and urine.

[0055] Seventh, zinc and MgZn 0.35 G 0.89、 MgZn 8.37 G 11.32The zinc element in the Mg3Zn3Gd phase is an important nutrient in the human body, which can help the human body build and maintain bone structure and strength. Adding zinc to biomedical magnesium alloys can significantly purify the alloy melt, refine the grains, and weaken the texture. The zinc-containing second phase formed can improve the strength, ductility and processing performance of biomedical magnesium alloys.

[0056] Eighth, Zirconium and MgZn 0.35 G 0.89、 MgZn 8.37 G 11.32 The zirconium element in the Mg3Zn3Gd phase has good biocompatibility and biostability. The appropriate amount of zirconium will not produce adverse reactions to the human body. It can participate in regulating the human immune system and help maintain the normal function of immune cells. At the same time, it has a certain positive effect on bone health and helps to enhance the strength and density of bones. Zirconium has high solubility and will not accumulate in the human body. It can be excreted from the body through sweat or urine. Adding zirconium to biomedical magnesium alloys can improve its mechanical properties and degradation properties because it has excellent grain refinement characteristics. Biomedical Mg-Gd-Zn-Zr-Dy-Sc rare earth magnesium alloy has excellent mechanical properties and processing properties, is non-toxic to cells and human tissues, can be degraded in body fluids to generate hydroxyapatite, has outstanding biocompatibility and biological activity, and can meet the requirements of being used as a medical implant material and being machined into related products.

[0057] The present invention uses rare earth elements gadolinium, dysprosium and scandium, as well as zinc and zirconium as alloying components, and obtains a biomedical rare earth magnesium alloy with a specific organizational structure through smelting, solution treatment, hot extrusion molding and aging treatment preparation methods. The strength and ductility of the alloy are significantly improved, and it has excellent mechanical processing properties, which can meet the requirements of being used as a biomedical material and processed into related products. In addition, the magnesium gadolinium zinc zirconium dysprosium scandium rare earth magnesium alloy material can promote cell growth and proliferation and degrade in body fluids to generate hydroxyapatite to further treat osteoporosis, increase bone density, strengthen bone quality and reduce the risk of re-fracture bone growth. These results show that the magnesium gadolinium zinc zirconium dysprosium scandium rare earth magnesium alloy is a potential ideal medical biological implant material.

[0058] Due to the synergistic antioxidant effect of the rare earth elements gadolinium, dysprosium and scandium, the grain refining effect of zirconium, and the zinc element's ability to purify the alloy melt, refine grains and weaken texture, the strength and plasticity of the prepared biomedical rare earth magnesium alloy have been significantly improved, and the degradation performance has been improved. The results of the in vitro cytotoxicity evaluation experiment show that the biomedical rare earth magnesium alloy is non-toxic to cells and human tissues, and can promote cell growth and proliferation, and has basic biosafety and excellent biocompatibility. Zinc is also a necessary nutrient for the human body, which can contribute to the healing and recovery of bone defects and the reconstruction of bones. The biomedical rare earth magnesium alloy of the present invention has high strength, good plasticity, excellent processing performance, degradability, non-toxicity, and excellent biological activity. It is a lightweight magnesium alloy implant material that can be used as a biomedical material.

[0059] The present invention also provides a method for preparing the above-mentioned biomedical rare earth magnesium alloy material, comprising the following steps:

[0060] Rare earth gadolinium, dysprosium, scandium and zirconium are mixed with pure magnesium and pure zinc particles using an intermediate alloy to form an alloy ingot, which is then subjected to solid solution treatment, hot extrusion and aging treatment to obtain a rare earth magnesium alloy material.

[0061] Specifically, the present invention firstly mixes and melts the raw materials into an alloy ingot. Specifically, the mixed melting into the alloy ingot comprises the following steps:

[0062] 1) Under protective atmosphere conditions, heating a magnesium ingot until it is melted to obtain a magnesium melt;

[0063] 2) adding zinc particles to the magnesium melt after heating until the magnesium melt is melted;

[0064] 3) heating again, adding magnesium-gadolinium master alloy, magnesium-dysprosium master alloy, and magnesium-scandium master alloy, heating and melting;

[0065] 4) Continue to increase the temperature and add magnesium-zirconium master alloy to obtain an alloy melt;

[0066] 5) refining the alloy melt to obtain a refined melt;

[0067] 6) The refined melt is heated and allowed to stand for a period of time before being cast into an ingot.

[0068] Specifically, the present invention firstly performs batching according to the designed alloy composition: the magnesium ingot, the zinc granules, and the intermediate alloy ingot are cut and polished (to remove the oxide scale on the surface), and then dried;

[0069] Next, the raw materials are weighed according to the mass ratio, and the weighed raw materials are preheated to 250-350° C., which can be 250, 300, 350, or any value between 250-350° C., and then kept warm.

[0070] The melting device is heated to 250-350°C, a preheated magnesium ingot is added to the device, and then a protective atmosphere is introduced, and the temperature is increased under the protective atmosphere to obtain a magnesium melt. The protective atmosphere condition is a mixed protective gas of SF6 and CO2 with a volume ratio of 1:(100-120). The volume ratio of SF6 to CO2 is 1:(100-120), which can be 1:100, 1:105, 1:110, 1:115, 1:120, or any value between 1:(100-120).

[0071] When the magnesium melt is heated to 710-810° C., zinc particles are added to the magnesium melt until it is melted, and stirred for 5-12 minutes while ensuring that the protective gas is normally introduced to obtain a magnesium-zinc mixed melt. The heating temperature is 710-780° C., which can be 710, 720, 730, 740, 750, 760, 770, 780, or any value between 710 and 780° C.

[0072] The temperature at which the magnesium-zinc mixed melt is heated again is 686-786°C, which can be 686, 696, 706, 716, 726, 736, 746, 756, 766, 776, 786, or any value between 686 and 786°C. Under the above temperature conditions, magnesium-gadolinium master alloy, magnesium-dysprosium master alloy, and magnesium-scandium master alloy are added and heated to melt. Among them, in the magnesium-gadolinium master alloy, the mass ratio of magnesium to gadolinium is 7:3; in the magnesium-dysprosium master alloy, the mass ratio of magnesium to dysprosium is 7:3; in the magnesium-scandium master alloy, the mass ratio of magnesium to scandium is 7:3.

[0073] After adding the master alloy, the melt temperature drops, and then continues to rise to 718-818° C., which can be 718, 728, 738, 748, 758, 768, 778, 788, 798, 808, 818, or any value between 718 and 818° C. Under the above temperature conditions, a magnesium-zirconium master alloy is added to obtain an alloy melt. In the magnesium-zirconium master alloy, the mass ratio of magnesium to zirconium is 7:3.

[0074] Then, the heating is stopped and the alloy melt is refined to obtain a refined melt. The refining temperature is 678-778°C, which can be 678, 688, 698, 708, 718, 728, 738, 748, 758, 768, 778, or any value between 678-778°C. The refining time is 10-15 minutes, which can be 10, 11, 12, 13, 14, 15, or any value between 10-15 minutes. A refining agent is added during the refining process, and the refining agent includes: 42-45% magnesium chloride, 28-30% potassium chloride, 5.5-6% sodium chloride. .5%, calcium fluoride 6.5-7.5%, magnesium oxide 13-15%, and the rest are water-insoluble matter; preferably, in some specific embodiments of the present invention, the refining agent includes: magnesium chloride 43.5%, potassium chloride 29%, sodium chloride 6%, calcium fluoride 7%, magnesium oxide 14.32%, and the rest are water-insoluble matter; the addition amount of the refining agent is 0.5%-3%, which can be 0.5wt%, 1wt%, 1.5wt%, 2wt%, 2.5wt%, 3wt%, or any value between 0.5% and 3%.

[0075] The refining agent is used for medical biological rare earth magnesium alloy. In order to remove metal and non-metal impurities suspended in the magnesium alloy liquid, after all the furnace charge is melted, the lower flux method should be used for refining. The refining should have a suitable melting point and an appropriate surface strength to remove impurities. Traditional refining pays attention to the refining effect, but ignores the surface covering and protection performance, and the harmful gases released meet the standards. The refining agent provided by the present invention is mainly composed of magnesium, sodium, calcium, chloride salt and fluoride salt, and has unique additives, a melting point of 410-430°C, which meets the requirements of magnesium alloy casting, has excellent refining effect, and can cover and protect; the specific gravity is 1.8-2.0, which has a large specific gravity difference with the alloy liquid, suitable viscosity, good chemical stability, no chemical reaction with the alloy furnace lining and furnace gas, no solvent impurities, small amount of harmful gases, and meets industrial hygiene standards and waste emission requirements.

[0076] The specific refining method includes: when the magnesium alloy is melted in a low-carbon steel crucible and heated to 718-818°C, the refining agent is continuously sprinkled on the alloy liquid surface, and the refining spoon is used to stir up and down to make the magnesium alloy liquid circulate, so that the refining agent is completely dissolved in the alloy liquid, and the contact between the refining agent dissolved in the alloy liquid and the oxide inclusions is increased. The adsorption time is usually maintained for about 10-15 minutes until the alloy liquid surface becomes bright.

[0077] Then, the refined melt is heated and allowed to stand for a period of time before being cast into an ingot. The temperature of the heating and standing is 696-796°C, which can be 696, 706, 716, 726, 736, 746, 756, 766, 776, 786, 793, or any value between 696 and 796°C, and the time is 15-25 minutes, which can be 15, 20, 25, or any value between 15 and 25 minutes; the casting temperature is 668-768°C, which can be 668, 678, 688, 698, 708, 718, 728, 738, 748, 758, 768, or any value between 668 and 768°C. The casting is carried out under gas protection, and finally a cylindrical alloy ingot with a cross-sectional diameter of 90-95 mm and a height of 150-400 mm is obtained. The obtained alloy ingot, i.e., the as-cast grain size is 64.057±4 μm.

[0078] After obtaining the alloy ingot, the alloy ingot is subjected to a solution treatment, wherein the solution treatment comprises: placing the alloy ingot in a heat treatment furnace, heating it to 460-560°C with the furnace under vacuum conditions, keeping the temperature for 6-10 hours, and then placing it in the air to cool to room temperature. The temperature of the solution treatment can be 460, 470, 480, 490, 500, 510, 520, 530, 540, 550, 560, or any value between 460-560°C; the time is 6, 7, 8, 9, 10, or any value between 6-10 hours.

[0079] After solution treatment, the grain size of the solution treated state is 70.653±3μm.

[0080] The alloy ingot after solid solution is hot extruded, the hot extrusion temperature is 320-380°C, which can be 320, 330, 340, 350, 360, 370, 380, or any value between 320-380°C, the extrusion speed is set between 0.02-1.5 m / s, the extrusion ratio is 8:1-13:1, which can be 8:1, 9:1, 10:1, 11:1, 12:1, 13:1, or any value between 8:1-13:1. The hot extruded grain size is 11.69±0.5 μm.

[0081] Finally, the alloy ingot is subjected to aging treatment, wherein the aging treatment temperature is 175-200° C., and may be 175, 180, 185, 190, 195, 200, or any value between 175-200° C., and the time is 20-40 hours, and may be 20, 25, 30, 35, 40, or any value between 20-40 hours. After the aging treatment, the grain size of the aging-treated state is 14.05±0.2 μm.

[0082] In order to obtain specific microstructure and mechanical properties, rare earth elements gadolinium, dysprosium, scandium and zirconium are added in the form of intermediate alloys, and zinc is added in the form of pure zinc particles. Based on this method, a suitable preparation process is adopted to prepare medical biological rare earth magnesium alloy materials.

[0083] The present invention also provides an application of the rare earth magnesium alloy material in preparing medical implant materials.

[0084] The beneficial effects of the present invention are as follows:

[0085] 1. The biodegradable magnesium-gadolinium-zinc-zirconium-dysprosium-scandium biomedical rare earth magnesium alloy has excellent mechanical properties, namely strength and plasticity, and can meet the requirements of being used as a medical implant material and being mechanically processed into related products. Its room temperature tensile strength, yield strength and elongation reach 200-450MPa, 105-255MPa and 7-20% respectively.

[0086] 2. The biomedical rare earth magnesium alloy of the present invention as an implant material does not contain alloy elements that are toxic to the human body, strictly meets the biological toxicity limit, and is safe and reliable. By analyzing the relative proliferation rate of cells after 100% immersion extract of the biomedical rare earth magnesium alloy of the present invention and 3T3 cell culture, the alloy is non-toxic to cells and human tissues, has good biological safety and excellent biocompatibility.

[0087] 3. The biomedical rare earth magnesium alloy material of the present invention is non-sensitizing to 3T3 cells and has a bactericidal function. It further treats osteoporosis by promoting cell growth and proliferation and degrading in body fluids to generate hydroxyapatite, thereby increasing bone density, strengthening bone quality and reducing the risk of recurrent fractures. It can be used as a biological implant material in the medical field.

[0088] In order to further understand the present invention, a medical biological rare earth magnesium alloy material provided by the present invention, a preparation method thereof and an application thereof are described below in conjunction with embodiments. The protection scope of the present invention is not limited by the following embodiments.

[0089] The refining agents used in the examples include:

[0090] Magnesium chloride 43.5%, potassium chloride 29%, sodium chloride 6%, calcium fluoride 7%, magnesium oxide 14.32%, and the rest are water-insoluble matter.

[0091] Example 1

[0092] The preparation method of Mg-1.17Gd-1.75Zn-0.43Zr-0.21Dy-0.22Sc medical biological rare earth magnesium alloy is as follows:

[0093] (1) 10 kg is prepared in each furnace. The raw materials for preparing the biomedical magnesium alloy are prepared in proportion (burnout amount is 10%), including 8.78626 kg of high-purity magnesium ingot, 0.73337 kg of magnesium-gadolinium master alloy, 0.07337 kg of magnesium-dysprosium master alloy, 0.07337 kg of magnesium-scandium master alloy, 0.14663 kg of magnesium-zirconium master alloy, and 0.187 kg of high-purity zinc particles. A low-carbon steel crucible is preheated. When the temperature rises to 310° C., the preheated high-purity magnesium ingot is added, and a mixed protective gas of SF6:CO2 with a volume ratio of 1:105 is introduced, and the temperature is raised;

[0094] (2) When the melt temperature in the low carbon steel crucible rises to 765°C, add high purity zinc particles and stir for 6-12 minutes;

[0095] (3) when the melt temperature in the low carbon steel crucible rises to 736° C., adding a magnesium-gadolinium master alloy with a mass ratio of 7:3, a magnesium-dysprosium master alloy with a mass ratio of 7:3, and a magnesium-scandium master alloy with a mass ratio of 7:3 into the low carbon steel crucible in sequence;

[0096] (4) Continue to raise the temperature. When the melt temperature in the low-carbon steel crucible rises to 768° C., add the magnesium-zirconium master alloy. After stirring, when the melt temperature drops to 728° C., add 0.5 wt % of a refining agent and refine in argon for 12 minutes.

[0097] (5) Heating, when the melt temperature rises to 746°C, let it stand for 19 minutes to remove the surface scum;

[0098] (6) When the melt temperature in the low-carbon steel crucible drops to 718°C, the alloy liquid is cast into a water-cooled mold to obtain a biomedical magnesium alloy ingot;

[0099] (7) Solution treatment: Place in a vacuum heat treatment furnace, evacuate and heat to 500°C, keep warm for 8 hours, take out and air cool;

[0100] (8) Hot extrusion molding: Turned into extrusion blank and hot extruded at 325℃, the die and barrel temperature is 335℃, the extrusion speed is set to 1m / s, and the extrusion ratio is 10:1.

[0101] (9) Aging treatment: Place in a vacuum heat treatment furnace, evacuate and heat to 175°C, keep warm for 24 hours, take out and air cool.

[0102] The chemical composition (mass percentage) of the prepared alloy is: 1.17wt% Gd, 1.75wt% Zn, 0.43wt% Zr, 0.21wt% Dy, 0.22wt% Sc, impurity elements (Fe≤0.002wt%; Cu≤0.0002wt%; Si≤0.002wt%; Ni≤0.0002wt%), and the balance is Mg.

[0103] The room temperature mechanical properties of the medical rare earth magnesium alloy prepared in Example 1 of the present invention were tested. The results showed that the tensile strength was 390±4 MPa, the yield strength was 180±1 MPa, and the elongation was 12±0.4%.

[0104] Example 2

[0105] The preparation method of Mg-1Gd-1.5Zn-0.4Zr-0.15Dy-0.16Sc medical biological rare earth magnesium alloy is as follows:

[0106] (1) 10 kg is prepared in each furnace. The raw materials for preparing the biomedical magnesium alloy are prepared in proportion (burnout amount 10%), including 8.71311 kg of high-purity magnesium ingot, 0.36663 kg of magnesium-gadolinium master alloy, 0.55 kg of magnesium-dysprosium master alloy, 0.05863 kg of magnesium-scandium master alloy, 0.14663 kg of magnesium-zirconium master alloy, and 0.165 kg of high-purity zinc particles. A low-carbon steel crucible is preheated. When the temperature rises to 315°C, the preheated high-purity magnesium ingot is added, and a mixed protective gas of SF6:CO2 with a volume ratio of 1:110 is introduced, and the temperature is raised;

[0107] (2) When the melt temperature in the low carbon steel crucible rises to 768°C, add high purity zinc particles and stir for 7-12 minutes;

[0108] (3) when the melt temperature in the low carbon steel crucible rises to 738° C., adding a magnesium-gadolinium master alloy with a mass ratio of 7:3, a magnesium-dysprosium master alloy with a mass ratio of 7:3, and a magnesium-scandium master alloy with a mass ratio of 7:3 into the low carbon steel crucible in sequence;

[0109] (4) Continue to raise the temperature. When the melt temperature in the low-carbon steel crucible rises to 765° C., add the magnesium-zirconium master alloy. After stirring, when the melt temperature drops to 735° C., add 0.5 wt % of a refining agent and refine in argon for 12 minutes.

[0110] (5) Heating, when the melt temperature rises to 748°C, let it stand for 18 minutes to remove the surface scum;

[0111] (6) When the melt temperature in the low-carbon steel crucible drops to 716°C, the alloy liquid is cast into a water-cooled mold to obtain a biomedical magnesium alloy ingot;

[0112] (7) Solution treatment: Place in a vacuum heat treatment furnace, evacuate and heat to 510°C, keep warm for 7.5 hours, take out and air cool;

[0113] (8) Hot extrusion molding: The material is turned into extrusion blank and hot extruded at 327°C. The die and barrel temperature is 338°C, the extrusion speed is set to 1.1m / s, and the extrusion ratio is 10:1.

[0114] (9) Aging treatment: Place in a vacuum heat treatment furnace, evacuate and heat to 177°C, keep warm for 24 hours, take out and air cool.

[0115] The chemical composition (mass percentage) of the prepared alloy is: 1wt% Gd, 1.5wt% Zn, 0.4wt% Zr, 0.15wt% Dy, 0.16wt% Sc, impurity elements (Fe≤0.0021wt%; Cu≤0.00021wt%; Si≤0.0022wt%; Ni≤0.00023wt%), and the balance is Mg.

[0116] The room temperature mechanical properties of the medical rare earth magnesium alloy prepared in Example 2 of the present invention were tested. The results showed that the tensile strength was 365±6 MPa, the yield strength was 165±4 MPa, and the elongation was 10±0.7%.

[0117] Example 3

[0118] The preparation method of Mg-1.5Gd-1.4Zn-0.37Zr-0.15Dy-0.19Sc medical biological rare earth magnesium alloy is as follows:

[0119] (1) 10 kg is prepared in each furnace. The raw materials for preparing the biomedical magnesium alloy are prepared in proportion (burnout amount is 10%), including 9.03074 kg of high-purity magnesium ingot, 0.555 kg of magnesium-gadolinium master alloy, 0.055 kg of magnesium-dysprosium master alloy, 0.06963 kg of magnesium-scandium master alloy, 0.13563 kg of magnesium-zirconium master alloy, and 0.154 kg of high-purity zinc particles. A low-carbon steel crucible is preheated. When the temperature rises to 322° C., the preheated high-purity magnesium ingot is added, and a mixed protective gas of SF6:CO2 with a volume ratio of 1:120 is introduced, and the temperature is raised;

[0120] (2) When the melt temperature in the low carbon steel crucible rises to 777°C, add high purity zinc particles and stir for 8-10 minutes;

[0121] (3) when the melt temperature in the low carbon steel crucible rises to 741° C., adding a magnesium-gadolinium master alloy with a mass ratio of 7:3, a magnesium-dysprosium master alloy with a mass ratio of 7:3, and a magnesium-scandium master alloy with a mass ratio of 7:3 into the low carbon steel crucible in sequence;

[0122] (4) Continue to raise the temperature. When the melt temperature in the low-carbon steel crucible rises to 771° C., add the magnesium-zirconium master alloy. After stirring, when the melt temperature drops to 731° C., add 0.5 wt % of a refining agent and refine in argon for 15 minutes.

[0123] (5) Heating, when the melt temperature rises to 748°C, let it stand for 20 minutes to remove the surface scum;

[0124] (6) When the melt temperature in the low-carbon steel crucible drops to 719°C, the alloy liquid is cast into a water-cooled mold to obtain a biomedical magnesium alloy ingot;

[0125] (7) Solution treatment: Place in a vacuum heat treatment furnace, evacuate and heat to 508°C, keep warm for 9 hours, take out and air cool;

[0126] (8) Hot extrusion molding: The material is turned into extrusion blank and hot extruded at 323°C. The die and barrel temperature is 332°C, the extrusion speed is set to 1.2m / s, and the extrusion ratio is 10:1.

[0127] (9) Aging treatment: Place in a vacuum heat treatment furnace, evacuate and heat to 178°C, keep warm for 23 hours, take out and air cool.

[0128] The chemical composition (mass percentage) of the prepared alloy is: 1.5wt% Gd, 1.4wt% Zn, 0.37wt% Zr, 0.15wt% Dy, 0.19wt% Sc, impurity elements (Fe≤0.0023wt%; Cu≤0.00024wt%; Si≤0.0025wt%; Ni≤0.00022wt%), and the balance is Mg.

[0129] The room temperature mechanical properties of the medical rare earth magnesium alloy prepared in Example 3 of the present invention were tested. The results showed that the tensile strength was 385±5 MPa, the yield strength was 170±1 MPa, and the elongation was 9±0.6%.

[0130] Comparative Example 1

[0131] The preparation method of Mg-1.75Zn-0.43Zr-0.21Dy-0.22Sc medical biological rare earth magnesium alloy is as follows:

[0132] (1) 10 kg is prepared in each furnace. The raw materials for preparing the biomedical magnesium alloy are prepared in proportion (burnout amount 10%), including 9.49224 kg of high-purity magnesium ingot, 0.077 kg of magnesium-dysprosium master alloy, 0.08063 kg of magnesium-scandium master alloy, 0.15763 kg of magnesium-zirconium master alloy, and 0.1925 kg of high-purity zinc particles. The low-carbon steel crucible is preheated. When the temperature rises to 310°C, the preheated high-purity magnesium ingot is added, and a mixed protective gas of SF6:CO2 with a volume ratio of 1:105 is introduced, and the temperature is raised;

[0133] (2) When the melt temperature in the low carbon steel crucible rises to 765°C, add high purity zinc particles and stir for 6-12 minutes;

[0134] (3) when the melt temperature in the low carbon steel crucible rises to 736° C., adding a magnesium-dysprosium master alloy with a mass ratio of 7:3 and a magnesium-scandium master alloy with a mass ratio of 7:3 into the low carbon steel crucible in sequence;

[0135] (4) Continue to raise the temperature. When the temperature of the melt in the low-carbon steel crucible rises to 768° C., add the magnesium-zirconium master alloy. After stirring, when the temperature of the melt drops to 728° C., add 0.5 wt % of a refining agent containing a mixture of magnesium chloride and magnesium oxide and perform argon refining for 12 minutes.

[0136] (5) Heating, when the melt temperature rises to 746°C, let it stand for 19 minutes to remove the surface scum;

[0137] (6) When the melt temperature in the low-carbon steel crucible drops to 718°C, the alloy liquid is cast into a water-cooled mold to obtain a biomedical magnesium alloy ingot;

[0138] (7) Solution treatment: Place in a vacuum heat treatment furnace, evacuate and heat to 500°C, keep warm for 8 hours, take out and air cool;

[0139] (8) Hot extrusion molding: Turned into extrusion blank and hot extruded at 325℃, the die and barrel temperature is 335℃, the extrusion speed is set to 1m / s, and the extrusion ratio is 10:1.

[0140] (9) Aging treatment: Place in a vacuum heat treatment furnace, evacuate and heat to 175°C, keep warm for 24 hours, take out and air cool.

[0141] The chemical composition (mass percentage) of the prepared alloy is: 1.75wt% Zn, 0.43wt% Zr, 0.21wt% Dy, 0.22wt% Sc, impurity elements (Fe≤0.002wt%; Cu≤0.0002wt%; Si≤0.002wt%; Ni≤0.0002wt%), and the balance is Mg.

[0142] The room temperature mechanical properties of the medical rare earth magnesium alloy prepared in Comparative Example 1 of the present invention were tested, and the results showed that the tensile strength was 150±1 MPa, the yield strength was 82±2 MPa, and the elongation was 3±0.3%.

[0143] Comparative Example 2

[0144] The preparation method of Mg-1.17Gd-1.75Zn-0.43Zr-0.22Sc medical biological rare earth magnesium alloy is as follows:

[0145] (1) 10 kg is prepared in each furnace. The raw materials for preparing the biomedical magnesium alloy are prepared in proportion (burnout amount is 10%), including 8.85963 kg of high-purity magnesium ingot, 0.73337 kg of magnesium-gadolinium master alloy, 0.07337 kg of magnesium-scandium master alloy, 0.14663 kg of magnesium-zirconium master alloy, and 0.187 kg of high-purity zinc particles. A low-carbon steel crucible is preheated. When the temperature rises to 310° C., the preheated high-purity magnesium ingot is added, and a mixed protective gas of SF6:CO2 with a volume ratio of 1:105 is introduced, and the temperature is raised;

[0146] (2) When the melt temperature in the low carbon steel crucible rises to 765°C, add high purity zinc particles and stir for 6-12 minutes;

[0147] (3) when the melt temperature in the low carbon steel crucible rises to 736° C., a magnesium-gadolinium master alloy with a mass ratio of 7:3 and a magnesium-scandium master alloy with a mass ratio of 7:3 are sequentially added into the low carbon steel crucible;

[0148] (4) Continue to raise the temperature. When the temperature of the melt in the low-carbon steel crucible rises to 768° C., add the magnesium-zirconium master alloy. After stirring, when the temperature of the melt drops to 728° C., add 0.5 wt % of a refining agent containing a mixture of magnesium chloride and magnesium oxide and perform argon refining for 12 minutes.

[0149] (5) Heating, when the melt temperature rises to 746°C, let it stand for 19 minutes to remove the surface scum;

[0150] (6) When the melt temperature in the low-carbon steel crucible drops to 718°C, the alloy liquid is cast into a water-cooled mold to obtain a biomedical magnesium alloy ingot;

[0151] (7) Solution treatment: Place in a vacuum heat treatment furnace, evacuate and heat to 500°C, keep warm for 8 hours, take out and air cool;

[0152] (8) Hot extrusion molding: Turned into extrusion blank and hot extruded at 325℃, the die and barrel temperature is 335℃, the extrusion speed is set to 1m / s, and the extrusion ratio is 10:1.

[0153] (9) Aging treatment: Place in a vacuum heat treatment furnace, evacuate and heat to 175°C, keep warm for 24 hours, take out and air cool.

[0154] The chemical composition (mass percentage) of the prepared alloy is: 1.17wt% Gd, 1.75wt% Zn, 0.43wt% Zr, 0.22wt% Sc, impurity elements (Fe≤0.002wt%; Cu≤0.0002wt%; Si≤0.002wt%; Ni≤0.0002wt%), and the balance is Mg.

[0155] The room temperature mechanical properties of the medical rare earth magnesium alloy prepared in Comparative Example 2 of the present invention were tested, and the results showed that the tensile strength was 215±1 MPa, the yield strength was 110±2 MPa, and the elongation was 4±0.4%.

[0156] Comparative Example 3

[0157] The preparation method of Mg-1.17Gd-1.75Zn-0.43Zr-0.21Dy medical biological rare earth magnesium alloy is as follows:

[0158] (1) 10 kg is prepared in each furnace. The raw materials for preparing the biomedical magnesium alloy are prepared in proportion (burnout amount is 10%), including 8.85963 kg of high-purity magnesium ingot, 0.73337 kg of magnesium-gadolinium master alloy, 0.07337 kg of magnesium-dysprosium master alloy, 0.14663 kg of magnesium-zirconium master alloy, and 0.187 kg of high-purity zinc particles. A low-carbon steel crucible is preheated. When the temperature rises to 310° C., the preheated high-purity magnesium ingot is added, and a mixed protective gas of SF6:CO2 with a volume ratio of 1:105 is introduced, and the temperature is raised;

[0159] (2) When the melt temperature in the low carbon steel crucible rises to 765°C, add high purity zinc particles and stir for 6-12 minutes;

[0160] (3) when the melt temperature in the low carbon steel crucible rises to 736° C., adding a magnesium-gadolinium master alloy with a mass ratio of 7:3 and a magnesium-dysprosium master alloy with a mass ratio of 7:3 into the low carbon steel crucible in sequence;

[0161] (4) Continue to raise the temperature. When the temperature of the melt in the low-carbon steel crucible rises to 768° C., add the magnesium-zirconium master alloy. After stirring, when the temperature of the melt drops to 728° C., add 0.5 wt % of a refining agent containing a mixture of magnesium chloride and magnesium oxide and perform argon refining for 12 minutes.

[0162] (5) Heating, when the melt temperature rises to 746°C, let it stand for 19 minutes to remove the surface scum;

[0163] (6) When the melt temperature in the low-carbon steel crucible drops to 718°C, the alloy liquid is cast into a water-cooled mold to obtain a biomedical magnesium alloy ingot;

[0164] (7) Solution treatment: Place in a vacuum heat treatment furnace, evacuate and heat to 500°C, keep warm for 8 hours, take out and air cool;

[0165] (8) Hot extrusion molding: Turned into extrusion blank and hot extruded at 325℃, the die and barrel temperature is 335℃, the extrusion speed is set to 1m / s, and the extrusion ratio is 10:1.

[0166] (9) Aging treatment: Place in a vacuum heat treatment furnace, evacuate and heat to 175°C, keep warm for 24 hours, take out and air cool.

[0167] The chemical composition (mass percentage) of the prepared alloy is: 1.17wt% Gd, 1.75wt% Zn, 0.43wt% Zr, 0.21wt% Dy, impurity elements (Fe≤0.002wt%; Cu≤0.0002wt%; Si≤0.002wt%; Ni≤0.0002wt%), and the balance is Mg.

[0168] The room temperature mechanical properties of the medical rare earth magnesium alloy prepared in Comparative Example 3 of the present invention were tested, and the results showed that the tensile strength was 200±2MPa, the yield strength was 102±3MPa, and the elongation was 3±0.3%.

[0169] Comparative Example 4

[0170] The preparation method of Mg-1.17Gd-1.75Zn-0.43Zr-0.21Dy-0.22Sc medical biological rare earth magnesium alloy is as follows:

[0171] (1) 10 kg is prepared in each furnace. The raw materials for preparing the biomedical magnesium alloy are prepared in proportion (burnout amount is 10%), including 8.78626 kg of high-purity magnesium ingot, 0.73337 kg of magnesium-gadolinium master alloy, 0.07337 kg of magnesium-dysprosium master alloy, 0.07337 kg of magnesium-scandium master alloy, 0.14663 kg of magnesium-zirconium master alloy, and 0.187 kg of high-purity zinc particles. A low-carbon steel crucible is preheated. When the temperature rises to 310° C., the preheated high-purity magnesium ingot is added, and a mixed protective gas of SF6:CO2 with a volume ratio of 1:105 is introduced, and the temperature is raised;

[0172] (2) when the melt temperature in the low carbon steel crucible rises to 765° C., a magnesium-gadolinium master alloy with a mass ratio of 7:3, a magnesium-dysprosium master alloy with a mass ratio of 7:3, a magnesium-scandium master alloy with a mass ratio of 7:3, a magnesium-zirconium master alloy with a mass ratio of 7:3 and high-purity zinc particles are added in sequence, and stirred for 6-12 minutes;

[0173] (3) After stirring, when the melt temperature drops to 728°C, add 0.5wt% of refining agent and refine in argon for 12 minutes;

[0174] (4) Heating, when the melt temperature rises to 746°C, let it stand for 19 minutes to remove the surface scum;

[0175] (5) When the melt temperature in the low-carbon steel crucible drops to 718°C, the alloy liquid is cast into a water-cooled mold to obtain a biomedical magnesium alloy ingot;

[0176] (6) Solution treatment: Place in a vacuum heat treatment furnace, evacuate and heat to 500°C, keep warm for 8 hours, take out and air cool;

[0177] (7) Hot extrusion molding: Turned into extrusion blank and hot extruded at 325℃, the die and barrel temperature is 335℃, the extrusion speed is set to 1m / s, and the extrusion ratio is 10:1.

[0178] (8) Aging treatment: Place in a vacuum heat treatment furnace, evacuate and heat to 175°C, keep warm for 24 hours, take out and air cool.

[0179] The chemical composition (mass percentage) of the prepared alloy is: 1.17wt% Gd, 1.75wt% Zn, 0.43wt% Zr, 0.21wt% Dy, 0.22wt% Sc, impurity elements (Fe≤0.002wt%; Cu≤0.0002wt%; Si≤0.002wt%; Ni≤0.0002wt%), and the balance is Mg.

[0180] The room temperature mechanical properties of the medical rare earth magnesium alloy prepared in Comparative Example 4 of the present invention were tested, and the results showed that the tensile strength was 350±2MPa, the yield strength was 130±2MPa, and the elongation was 5±0.6%.

[0181] Comparative Example 5

[0182] The preparation method of Mg-1.17Gd-1.75Zn-0.43Zr-0.21Dy-0.22Sc medical biological rare earth magnesium alloy is as follows:

[0183] (1) 10 kg is prepared in each furnace. The raw materials for preparing the biomedical magnesium alloy are prepared in proportion (burnout amount is 10%), including 8.78626 kg of high-purity magnesium ingot, 0.73337 kg of magnesium-gadolinium master alloy, 0.07337 kg of magnesium-dysprosium master alloy, 0.07337 kg of magnesium-scandium master alloy, 0.14663 kg of magnesium-zirconium master alloy, and 0.187 kg of high-purity zinc particles. A low-carbon steel crucible is preheated. When the temperature rises to 310° C., the preheated high-purity magnesium ingot is added, and a mixed protective gas of SF6:CO2 with a volume ratio of 1:105 is introduced, and the temperature is raised;

[0184] (2) When the melt temperature in the low carbon steel crucible rises to 765°C, add high purity zinc particles and stir for 6-12 minutes;

[0185] (3) when the melt temperature in the low carbon steel crucible rises to 736° C., adding a magnesium-gadolinium master alloy with a mass ratio of 7:3, a magnesium-dysprosium master alloy with a mass ratio of 7:3, and a magnesium-scandium master alloy with a mass ratio of 7:3 into the low carbon steel crucible in sequence;

[0186] (4) Continue to increase the temperature, and when the melt temperature in the low carbon steel crucible rises to 768°C, add the magnesium zirconium master alloy;

[0187] (5) Heating, when the melt temperature rises to 746°C, let it stand for 19 minutes to remove the surface scum;

[0188] (6) When the melt temperature in the low-carbon steel crucible drops to 718°C, the alloy liquid is cast into a water-cooled mold to obtain a biomedical magnesium alloy ingot;

[0189] (7) Solution treatment: Place in a vacuum heat treatment furnace, evacuate and heat to 500°C, keep warm for 8 hours, take out and air cool;

[0190] (8) Hot extrusion molding: Turned into extrusion blank and hot extruded at 325℃, the die and barrel temperature is 335℃, the extrusion speed is set to 1m / s, and the extrusion ratio is 10:1.

[0191] (9) Aging treatment: Place in a vacuum heat treatment furnace, evacuate and heat to 175°C, keep warm for 24 hours, take out and air cool.

[0192] The chemical composition (mass percentage) of the prepared alloy is: 1.17wt% Gd, 1.75wt% Zn, 0.43wt% Zr, 0.21wt% Dy, 0.22wt% Sc, impurity elements (Fe≤0.002wt%; Cu≤0.0002wt%; Si≤0.002wt%; Ni≤0.0002wt%), and the balance is Mg.

[0193] The room temperature mechanical properties of the medical rare earth magnesium alloy prepared in Comparative Example 5 of the present invention were tested, and the results showed that the tensile strength was 335±1 MPa, the yield strength was 130±6 MPa, and the elongation was 5±0.7%.

[0194] Figure 1 The metallographic photographs of the alloy embodiment 1 of the present invention are as follows: (a) as-cast (b) as-solution treated (c) as-hot extruded (perpendicular to the extrusion direction) (d) as-aged (perpendicular to the extrusion direction). It can be seen from the figure that the specific metallographic structure is the main reason why the biomedical rare earth magnesium alloy has excellent mechanical properties.

[0195] Figure 2 The following are scanning electron microscope photos of the alloy embodiment 1 of the present invention: (a) as-cast (b) solution treated (c) hot extruded (along the extrusion direction) (d) aging treated (along the extrusion direction). It can be seen from the figure that the specific scanning structure is the main reason why the biomedical rare earth magnesium alloy has excellent mechanical properties.

[0196] Figure 3This is a typical scanning electron microscope photo of the second phase in the aging treated alloy of Example 1 of the present invention. It can be seen from the figure that the phase containing a specific structure is the main reason why the biomedical rare earth magnesium alloy has excellent mechanical properties.

[0197] Depend on Figure 1 to Figure 3 It can be seen that a special layered MgZn 0.35 G 0.89 and MgZn 8.37 G 11.32 Phase and Mg3Zn3Gd phase with face-centered cubic structure. In addition to Mg element, the phase also contains Gd and Zn elements. It is an intermetallic compound with a size of 3 microns to 17 microns. It is coherent or semi-coherent with the matrix. The precipitated phase has high strength and good plasticity. It is finely dispersed and continuously or discontinuously distributed at the grain boundaries, which plays a dual role in both improving the strength and improving the plasticity of the alloy.

[0198] The alloy element content in the medical biological rare earth magnesium alloy prepared in Comparative Examples 1 to 3 is not within the protection range, and the metallographic structure, scanning electron microscope structure and typical second phase generated in Example 1 are not generated, which is the main reason for the poor mechanical properties.

[0199] Comparative Example 4 changes the order of adding the raw materials, resulting in poor tensile strength, yield strength and elongation.

[0200] Comparative Example 5 was not refined, resulting in poor tensile strength, yield strength and elongation.

[0201] The element composition of the obtained medical biological rare earth magnesium alloy material is shown in Table 1

[0202] Table 1 Element composition of medical biological rare earth magnesium alloy materials (unit: wt%)

[0203]

[0204] Test Example 1

[0205] The rare earth magnesium alloy materials prepared in the above examples and comparative examples were tested for mechanical properties, including room temperature tensile strength, yield strength, and elongation. The test methods are as follows:

[0206] According to the American Society for Testing and Materials standard ASTM E8-04, the shape of the tensile specimen is dumbbell-shaped, and the sample size is based on l o =5.65×A o -1 / 2 Formula preparation. Wherein, A o is the cross-sectional area of ​​the sample, l oThe tensile test was carried out on an Instron 1121 material testing machine at a tensile rate of 1.0 mm / min, and the test was performed 5 times in parallel to obtain the average value.

[0207] 1. Room temperature tensile strength

[0208] The room temperature tensile strength is the maximum stress value that the biomedical rare earth magnesium alloy sample can withstand before the tensile test material breaks, that is, σ b =F b / A o

[0209] In the formula, F b is the maximum force that the specimen withstands before breaking, A o is the original cross-sectional area of ​​the specimen.

[0210] 2. Yield strength

[0211] The yield strength is the minimum stress value of the biomedical rare earth magnesium alloy sample when the tensile test material begins to produce obvious plastic deformation, that is, σ s =F s / A o

[0212] In the formula, F s is the force when the specimen yields, A o is the original cross-sectional area of ​​the specimen.

[0213] 3. Elongation

[0214] The elongation is the ratio of the gauge length growth of the biomedical rare earth magnesium alloy sample after the tensile test material is broken to the original gauge length, that is, δ = (l k -l o ) / l o ×100%

[0215] In the formula, l k is the gauge length after the specimen breaks, l o is the original gauge length of the specimen.

[0216] The test results are shown in Table 2

[0217] Table 2 Mechanical properties test results of rare earth magnesium alloy materials prepared in Examples and Comparative Examples

[0218] Room temperature tensile strength Yield Strength Elongation Example 1 390±4MPa 180±1MPa 12±0.4％ Example 2 365±6MPa 165±4MPa 10±0.7％ Example 3 385±5MPa 170±1MPa 9±0.6％ Comparative Example 1 150±1MPa 82±2MPa 3±0.3％ Comparative Example 2 215±1MPa 110±2MPa 4±0.4％ Comparative Example 3 200±2MPa 102±3MPa 3±0.3％ Comparative Example 4 350±2MPa 130±2MPa 5±0.6％ Comparative Example 5 335±1MPa 130±6MPa 5±0.7％

[0219] Test Example 2

[0220] The alloy prepared in Example 1 was subjected to an in vitro cytotoxicity test. The test method is as follows:

[0221] According to the international standard ISO10993-5:2009, 3T3 cells were used to make a basic evaluation of the toxicity of the alloy. DMEM culture medium containing 10% fetal bovine serum and 100U / mL penicillin was added to the alloy sample after UV sterilization, and the alloy sample was placed in a constant temperature incubator at 37°C and 5% CO2 for 24 hours to obtain 100% leaching solution, which was then sterilized with a 0.22μm microporous filter membrane for use. The positive control group was a culture medium containing 0.64% phenol.

[0222] Results Figure 4 ,and Figure 4 (b) Compared with round, non-adherent and unhealthy cells, Figure 4 (a) is a morphological photograph of 3T3 cells cultured for 7 days after using the Mg-1.17Gd-1.75Zn-0.43Zr-0.21Dy-0.22Sc extract in Example 1 of the present invention: 100% immersion in the extract. Most of the cells cultured in the 100% extract of the present invention alloy are in a normal and healthy state (attached to the wall in an elongated shape), indicating that the present invention alloy is non-toxic and non-sensitizing to cells and human tissues, and has a bactericidal function. At the same time, the alloy extract can promote cell growth and proliferation, and has good biosafety and excellent biocompatibility to ensure that it can be used in the medical field.

[0223] Figure 5 (a, b) are scanning electron microscope photos and energy spectra of hydroxyapatite, the main component of human bone, generated on the surface of the alloy of the present invention after 7 days of degradation in simulated body fluid. The hydroxyapatite generated by degradation can further treat osteoporosis, increase bone density, strengthen bone quality and reduce the risk of re-fracture.

[0224] The above is only a preferred embodiment of the present invention. It should be pointed out that for ordinary technicians in this technical field, several improvements and modifications can be made without departing from the principle of the present invention. These improvements and modifications should also be regarded as the scope of protection of the present invention.

Claims

1. A medical biological rare earth magnesium alloy material, characterized in that: These include the elements magnesium, gadolinium, zinc, zirconium, dysprosium and scandium.

2. The medical biological rare earth magnesium alloy material according to claim 1, characterized in that: include: 0.5-2.5wt.% Gd, 0.5-2.0wt.% Zn, 0.1-1.0wt.% Zr, 0.1-0.5wt.% Dy, 0.1-0.5wt.% Sc, and the rest are Mg and unavoidable impurity elements.

3. The medical biological rare earth magnesium alloy material according to claim 2, characterized in that: Among the impurity elements, Fe≤0.005wt.%, Cu≤0.0005wt.%, Si≤0.005wt.%, and Ni≤0.0005wt.%.

4. The medical biological rare earth magnesium alloy material according to claim 1, characterized in that: The medical biological rare earth magnesium alloy material comprises MgZn having a layered structure 0.35 G 0.89 MgZn 8.37 G 11.32 phase and Mg3Zn3Gd phase with face-centered cubic structure; Preferably, the Mg element, the Gd element and the Zn element also form an intermetallic compound with a size of 3 to 17 μm; further preferably, the intermetallic compound is in a coherent or semi-coherent relationship with the medical biological rare earth magnesium alloy material matrix.

5. A method for preparing a medical biological rare earth magnesium alloy material as claimed in any one of claims 1 to 4, characterized in that: The following steps are involved: The gadolinium element, the dysprosium element, the scandium element and the zirconium element are mixed with magnesium and zinc using an intermediate alloy and smelted into an alloy ingot, which is then subjected to a solid solution treatment, hot extrusion and aging treatment to obtain a rare earth magnesium alloy material.

6. The preparation method according to claim 5, characterized in that: The mixed smelting into alloy ingots comprises the following steps: 1) Under protective atmosphere conditions, heating a magnesium ingot until it is melted to obtain a magnesium melt; 2) adding zinc particles to the magnesium melt after heating until the magnesium melt is melted; 3) heating again, adding magnesium-gadolinium master alloy, magnesium-dysprosium master alloy, and magnesium-scandium master alloy, heating and melting; 4) Continue to increase the temperature and add magnesium-zirconium master alloy to obtain an alloy melt; 5) refining the alloy melt to obtain a refined melt; 6) The refined melt is heated and allowed to stand for a period of time before being cast into an ingot.

7. The preparation method according to claim 6, characterized in that: In step 1), the protective atmosphere condition is a mixed protective gas of SF6 and CO2 in a volume ratio of 1: (100-120); In step 2), the heating temperature is 710-810°C; In step 3), the temperature of the re-heating is 686-786° C.; in the magnesium-gadolinium master alloy, the mass ratio of magnesium to gadolinium is 7:3; in the magnesium-dysprosium master alloy, the mass ratio of magnesium to dysprosium is 7:3; in the magnesium-scandium master alloy, the mass ratio of magnesium to scandium is 7:3; In step 4), the temperature of the continued heating is 718-818° C.; the mass ratio of magnesium to zirconium in the magnesium-zirconium master alloy is 7:3; In step 5), the refining temperature is 678-778°C and the time is 0.5-5 min; a refining agent is added during the refining process, and the refining agent includes: 42-45% magnesium chloride, 28-30% potassium chloride, 5.5-6.5% sodium chloride, 6.5-7.5% calcium fluoride, 13-15% magnesium oxide, and the rest is water-insoluble matter; the amount of the refining agent added is 0.5%-3%; In step 6), the temperature of the heating and standing is 696-796°C for 15-25 minutes; the temperature of the casting is 668-768°C.

8. The preparation method according to claim 5, characterized in that: The solution treatment comprises: placing the alloy ingot in a heat treatment furnace, heating it to 460-560° C. in a vacuum furnace, keeping the temperature for 6-10 hours, and then placing it in air to cool to room temperature; The temperature of the hot extrusion is 320-380°C, the extrusion speed is set between 0.02-1m / s, and the extrusion ratio is 8:1-13:1; The aging treatment is carried out at a temperature of 175 to 200° C. and for a time of 20 to 40 hours.

9. Use of the rare earth magnesium alloy material according to any one of claims 1 to 3 in the preparation of medical implant materials.

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