Semi-solid alloy material for medical devices and preparation method thereof

Abstract

The present invention provides a semi-solid alloy material for medical devices and a preparation method thereof. The preparation method comprises the following steps: preparing magnesium alloy A and magnesium alloy B, preparing the magnesium alloy A into a powder of 20-50 μm, transferring the magnesium alloy B into a container and heating it to obtain a slurry having a temperature 10-20°C above the liquidus, wherein the mass fraction of iron in the magnesium alloy A is 0.02-0.06%, and the mass fraction of iron in the magnesium alloy B is 0-0.004%, placing a heat removal device with exhaust holes on its surface in the container, the heat removal device being provided with a flow channel for conveying gas and powder, an acceleration device being provided in the flow channel for accelerating the powder, inputting the gas and powder into the flow channel at a gas flow rate of 1-10 L / min, and starting the acceleration device, and waiting for the temperature of the slurry to drop to no more than 5°C above the liquidus to obtain the semi-solid alloy material.

Description

Technical Field

[0001] The present invention relates to the field of semi-solid alloy manufacturing, in particular to a semi-solid alloy material for medical devices and a preparation method thereof. Background Art

[0002] Titanium alloys are widely used in the field of medical devices as implantable materials in surgical operations. However, titanium alloys have strong stability and cannot be degraded in the body. They need to be removed through a secondary operation, which aggravates the pain of patients. Degradable implant materials such as polymer materials have better biosafety and can be degraded in the body, but their strength is difficult to meet the requirements for use. Magnesium alloy materials have a mechanical strength similar to that of bone tissue and can be degraded in the human body. Moreover, magnesium ions are a component element in the human body and have little harm to the human body. Magnesium alloys used in implantable materials need to have not only high surface quality and high mechanical strength, but also a controllable corrosion rate, that is, a low corrosion rate in the early stage to avoid excessive reduction in the performance of the implantable material and failure to play a fixing role, and a faster corrosion rate in the later stage to avoid affecting the healing of bone tissue.

[0003] Existing technologies typically increase the corrosion rate of magnesium alloys by adding other elements, and then applying a corrosion-resistant coating to the surface of the formed material to prevent premature contact of the magnesium alloy with body fluids. However, the mechanical strength of these coatings is significantly lower than that of the magnesium alloy, and during use, the coatings are prone to wear, exposing the internal magnesium alloy, causing premature degradation of the magnesium alloy. The above effect can also be achieved by forming a corrosion-resistant metal coating on the surface of the magnesium alloy casting. However, when the metal coating surface is corroded and a notch is formed, the protective effect of the surface corrosion-resistant layer is greatly weakened, and the degradation rate of the magnesium alloy casting will rapidly increase and continue to accelerate, potentially exceeding the human body's tolerance to magnesium.

[0004] Therefore, it is necessary to propose a semi-solid alloy material for medical devices and a preparation method thereof. Summary of the Invention

[0005] In order to solve the problem that the corrosion rate of magnesium alloy materials in the body is difficult to control, it is necessary to provide a semi-solid alloy material for medical devices and a preparation method thereof.

[0006] A first aspect of the present invention provides a method for preparing a semi-solid alloy material for medical devices, characterized in that it comprises the following steps:

[0007] Magnesium alloy A and magnesium alloy B are prepared, wherein the magnesium alloy A is prepared into a powder of 20-50 μm, and the magnesium alloy B is transferred into a container and heated to obtain a slurry having a temperature 10-20° C. above the liquidus, wherein the mass fraction of iron in the magnesium alloy A is 0.02-0.06%, and the mass fraction of iron in the magnesium alloy B is 0-0.004%.

[0008] A heat removal device with exhaust holes on its surface is placed in the container, wherein the heat removal device is provided with a flow channel for conveying gas and powder, and an acceleration device for accelerating the powder is provided in the flow channel.

[0009] The gas and the powder are input into the flow channel at a gas flow rate of 1-10 L / min, and the acceleration device is started. When the temperature of the slurry drops to no more than 5° C. above the liquidus, the semi-solid alloy material is obtained.

[0010] This solution uses magnesium alloy A as an external particle to provide a nucleation core, and the slurry of magnesium alloy B grows around the external particles to form grains. On the one hand, magnesium alloy A provides a large number of heterogeneous nuclei, resulting in refined grains, thereby improving the corrosion resistance of the grains; on the other hand, the surface of the grains and the intergranular spaces have a lower Fe concentration, which has higher corrosion resistance, can reduce the corrosion rate of the magnesium alloy casting during early use, and prevent the grain core from being exposed to the body fluid environment. The grain core has a higher Fe concentration. After the magnesium alloy casting has been used for a period of time, the surface of the grains and the intergranular spaces are gradually corroded, and the grain core is exposed to the body fluid. Fe and Mg can play the role of primary batteries, thereby increasing the corrosion rate of the magnesium alloy. Therefore, the above-mentioned magnesium alloy not only has a lower corrosion rate in the early stage to avoid the rapid decrease in the strength of the magnesium alloy casting, but also has a higher corrosion rate in the later stage to avoid affecting the healing of bone tissue. At the same time, unlike the method of coating the surface of magnesium alloy castings with a corrosion-resistant shell, the accelerated corrosion caused by the primary battery in this solution is dispersed at the cores of each exposed grain. The accelerated corrosion of a single grain core does not lead to the initiation of accelerated corrosion of other grain cores, so the corrosion effect will not continue to increase to exceed the tolerance of the human body. The casting will degrade evenly and there will be no local rapid degradation. The above-mentioned material prepared by the semi-solid alloy preparation process can meet the requirements of high surface quality in the field of medical devices. Among them, the iron content in magnesium alloy A determines the corrosion rate of magnesium alloy castings in the later stage. If the content is too low, the corrosion rate is too slow and will affect the healing of bone tissue; if the content is too high, the excessively fast corrosion rate will produce too many magnesium ions, which may exceed the tolerance of the human body and affect health.

[0011] Furthermore, the mass fraction of iron in the magnesium alloy A is 0.04%. Castings made of the semi-solid alloy material within the above range have a suitable corrosion rate.

[0012] Furthermore, the magnesium alloy A comprises, by weight, 8.5-9.5% aluminum, 0.45-0.90% zinc, 0.17-0.4% manganese, 0-0.05% silicon, 0-0.025% copper, 0-0.001% nickel, 0.02-0.06% iron, and the balance being magnesium. The above material has good mechanical properties and a suitable corrosion rate.

[0013] Furthermore, the magnesium alloy B is AZ91D. The mass fraction of Fe in AZ91D is ≤0.004%, and it has good corrosion resistance and mechanical strength.

[0014] Furthermore, magnesium alloy B contains at least one of boron, calcium, and sr. These elements can refine the grain size and improve the mechanical properties and corrosion resistance of the casting. Furthermore, magnesium alloy B contains 0.3-0.9% by mass of sr. This mass fraction of sr can form an AlSr phase with aluminum, further improving the corrosion resistance of the magnesium alloy.

[0015] Furthermore, the powder is prepared by gas atomization. Gas atomization is a common method for preparing micron-sized powders. Magnesium alloy A is melted into a liquid in a vacuum melting furnace and then sprayed at a constant speed through an atomizing nozzle. The liquid collides with the high-speed gas at the nozzle, breaking it into small droplets. The droplets cool and solidify into particles, which are then sieved to obtain the desired powder. Of course, other methods for preparing micron-sized powders can also be used.

[0016] Furthermore, the ratio of the powder particle size to the exhaust hole diameter is 1:(2-5). This can prevent the powder from leaking during the filling and standing process, and will not affect the discharge of the powder under the action of the acceleration device.

[0017] Furthermore, the acceleration device is an ultrasonic horn with an ultrasonic power of 1-3kW and an ultrasonic frequency of 10-30kHz. The ultrasonic action can make the powder move violently in the flow channel, thereby increasing the speed of the powder when leaving the exhaust hole.

[0018] A second aspect of the present invention provides a semi-solid alloy material for medical devices, which is prepared by the above-mentioned preparation method.

[0019] The above-mentioned semi-solid alloy material is applied in the field of medical devices and can be used as a degradable implant material. It has a low corrosion rate in the early stage of implantation to avoid excessive decrease in the strength of magnesium alloy castings, and a high corrosion rate in the later stage to avoid affecting the healing of bone tissue. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] Figure 1 This is a microscope image of the casting of Example 1.

[0021] Figure 2 The graph is a test chart of the in vitro biodegradability of the samples of Example 1 and Comparative Example 1.

[0022] Figure 3 Schematic diagram of a device for preparing refined semi-solid magnesium alloy slurry according to an embodiment. DETAILED DESCRIPTION

[0023] For ease of understanding of the present application, the present application will be described more fully below. The present application can be implemented in many different forms and is not limited to the embodiments described herein. On the contrary, the purpose of providing these embodiments is to make the understanding of the disclosure of the present application more thorough and comprehensive.

[0024] In addition, the terms "first" and "second" are used for descriptive purposes only and should not be understood as indicating or implying relative importance or implicitly indicating the number of the indicated technical features. Therefore, the features defined as "first" and "second" may explicitly or implicitly include at least one of such features. In the description of the application, the meaning of "multiple" is at least two, such as two, three, etc., unless otherwise clearly and specifically defined. In the description of this application, the meaning of "several" is at least one, such as one, two, etc., unless otherwise clearly and specifically defined.

[0025] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by those skilled in the art to which this application pertains. The terms used herein in the specification of this application are for the purpose of describing specific embodiments only and are not intended to limit this application. The term "and / or" as used herein includes any and all combinations of one or more of the associated listed items.

[0026] In this application, the technical features described in an open manner include closed technical solutions composed of the listed features, and also include open technical solutions containing the listed features.

[0027] In this application, when referring to numerical ranges, unless otherwise specified, the numerical ranges are considered continuous and include the minimum and maximum values of the range, as well as every value between such minimum and maximum values. Further, when a range refers to an integer, every integer between the minimum and maximum values of the range is included. In addition, when multiple ranges are provided to describe a feature or characteristic, the ranges can be combined. In other words, unless otherwise specified, all ranges disclosed herein should be understood to include any and all subranges subsumed therein.

[0028] Unless otherwise specified, the percentage contents mentioned in this application refer to mass percentage for solid-liquid mixture and solid-solid mixture, and refer to volume percentage for liquid-liquid mixture.

[0029] The percentage concentrations mentioned in this application, unless otherwise specified, refer to the final concentration, which refers to the percentage of the added component in the system after the addition of the component.

[0030] The temperature parameters in this application, unless otherwise specified, allow for both constant temperature treatment and treatment within a certain temperature range. The constant temperature treatment allows for temperature fluctuations within the precision range of instrument control.

[0031] The "particles" mentioned in this application, or materials with a defined particle size distribution, are not necessarily spherical in shape but may be irregular, primary or secondary. The particle size of irregular particles is the average of their maximum and minimum diameters.

[0032] like Figure 3 As shown, a device 100 for preparing a refined semi-solid magnesium alloy slurry comprises a container 1, a magnesium alloy slurry 2, and a heat removal device 3 having a flow channel 4. An accelerator 5 is fixed in the flow channel 4. The accelerator in this embodiment is an ultrasonic horn, and in other embodiments it may also be a stirrer. An exhaust hole 31 is provided on the surface of the heat removal device 3. Powder 8 is pre-placed in the flow channel 4 (in some embodiments, the powder 8 may be mixed with gas first and then input into the flow channel 4 through the gas), the gas source is started to allow the gas to enter the flow channel 4, and ultrasound is started to cause the powder 8 to move rapidly in the flow channel and flow out of the exhaust hole 31 together with the gas into the magnesium alloy slurry 2. At this time, bubbles 6 and grains 7 are generated inside the magnesium alloy slurry 2, and the bubbles 6 and grains 7 around the heat removal device 3 move toward the bottom and edge of the container 1 under the drive of the high-speed powder 8.

[0033] Example 1: Composition of magnesium alloy A: 9% aluminum, 0.45% zinc, 0.17% manganese, 0.03% silicon, 0.01% copper, 0.001% nickel, 0.06% iron, and the balance being magnesium.

[0034] The composition of magnesium alloy B is: 9% aluminum, 0.45% zinc, 0.17% manganese, 0.03% silicon, 0.01% copper, 0.001% nickel, 0.002% iron, 0.3% Sr, and the balance is magnesium.

[0035] Prepare 1 kg of magnesium alloy A and 10 kg of magnesium alloy B. Prepare magnesium alloy A into 20 μm (particle size) powder by gas atomization. Transfer magnesium alloy B into a spoon and heat it to obtain a slurry with a temperature 10°C above the liquidus.

[0036] 0.5 kg of the above-mentioned powder was added to the flow channel of the heat removal device. The heat removal device with exhaust holes (aperture of 100 μm) on the surface was placed in the crucible, with the lower end of the heat removal device 2 mm away from the bottom of the container. The gas source was started to allow argon gas to enter the flow channel at a gas flow rate of 5 L / min, and the ultrasonic horn arranged in the flow channel was started with an ultrasonic power of 1 kW and an ultrasonic frequency of 10 kHz. When the temperature of the magnesium alloy slurry dropped to 5°C above the liquidus, a semi-solid magnesium alloy material was obtained.

[0037] Example 2: Composition of magnesium alloy A: 9% aluminum, 0.45% zinc, 0.17% manganese, 0.03% silicon, 0.01% copper, 0.001% nickel, 0.02% iron, and the balance being magnesium.

[0038] The composition of magnesium alloy B is: 9% aluminum, 0.45% zinc, 0.17% manganese, 0.03% silicon, 0.01% copper, 0.001% nickel, 0.002% iron, 0.3% Sr, and the balance is magnesium.

[0039] Prepare 0.2 kg of magnesium alloy A and 10 kg of magnesium alloy B. Prepare magnesium alloy A into 50 μm powder by gas atomization. Transfer magnesium alloy B into a spoon and heat it to obtain a slurry with a temperature 20°C above the liquidus.

[0040] 0.01 kg of the above-mentioned powder was added to the flow channel of the heat removal device. The heat removal device with exhaust holes (aperture of 100 μm) on the surface was placed in the crucible, with the lower end of the heat removal device 2 mm away from the bottom of the container. The gas source was started to allow argon gas to enter the flow channel at a gas flow rate of 10 L / min, and the ultrasonic horn arranged in the flow channel was started with an ultrasonic power of 3 kW and an ultrasonic frequency of 30 kHz. When the temperature of the magnesium alloy slurry dropped to 5°C below the liquidus, a semi-solid magnesium alloy material was obtained.

[0041] Example 3: Composition of magnesium alloy A: 9% aluminum, 0.45% zinc, 0.17% manganese, 0.03% silicon, 0.01% copper, 0.001% nickel, 0.06% iron, and the balance being magnesium.

[0042] The composition of magnesium alloy B is: 9% aluminum, 0.45% zinc, 0.17% manganese, 0.03% silicon, 0.01% copper, 0.001% nickel, 0.004% iron, 0.3% Sr, and the balance is magnesium.

[0043] Prepare 1 kg of magnesium alloy A and 10 kg of magnesium alloy B. Prepare magnesium alloy A into 20 μm powder by gas atomization. Transfer magnesium alloy B into a spoon and heat it to obtain a slurry with a temperature 10°C above the liquidus.

[0044] 0.5 kg of the above-mentioned powder was added to the flow channel of the heat removal device. The heat removal device with exhaust holes (aperture of 100 μm) on the surface was placed in the crucible, with the lower end of the heat removal device 2 mm away from the bottom of the container. The gas source was started to allow argon gas to enter the flow channel at a gas flow rate of 5 L / min, and the ultrasonic horn arranged in the flow channel was started with an ultrasonic power of 1 kW and an ultrasonic frequency of 10 kHz. When the temperature of the magnesium alloy slurry dropped to 5°C above the liquidus, a semi-solid magnesium alloy material was obtained.

[0045] Example 4: Composition of magnesium alloy A: 8.5% aluminum, 0.9% zinc, 0.17% manganese, 0.01% silicon, 0.025% copper, 0.001% nickel, 0.06% iron, and the balance being magnesium.

[0046] Magnesium alloy B is AZ91D, and its composition is: 8.5% aluminum, 0.45% zinc, 0.4% manganese, 0.03% silicon, 0.01% copper, 0.001% nickel, 0.004% iron, 0.3% Sr, and the balance is magnesium.

[0047] Prepare 1 kg of magnesium alloy A and 10 kg of magnesium alloy B. Prepare magnesium alloy A into 20 μm powder by gas atomization. Transfer magnesium alloy B into a spoon and heat it to obtain a slurry with a temperature 10°C above the liquidus.

[0048] 0.5 kg of the above-mentioned powder was added to the flow channel of the heat removal device. The heat removal device with exhaust holes (aperture of 100 μm) on the surface was placed in the crucible, with the lower end of the heat removal device 2 mm away from the bottom of the container. The gas source was started to allow argon gas to enter the flow channel at a gas flow rate of 5 L / min, and the ultrasonic horn arranged in the flow channel was started with an ultrasonic power of 1 kW and an ultrasonic frequency of 10 kHz. When the temperature of the magnesium alloy slurry dropped to 5°C above the liquidus, a semi-solid magnesium alloy material was obtained.

[0049] Example 5: Composition of magnesium alloy A: 9% aluminum, 0.45% zinc, 0.17% manganese, 0.03% silicon, 0.01% copper, 0.001% nickel, 0.06% iron, and the balance being magnesium.

[0050] The composition of magnesium alloy B is: 9% aluminum, 0.45% zinc, 0.17% manganese, 0.03% silicon, 0.01% copper, 0.001% nickel, 0.002% iron, 0.3% Sr, 0.1% Ca, and the balance is magnesium.

[0051] Prepare 1 kg of magnesium alloy A and 10 kg of magnesium alloy B. Prepare magnesium alloy A into 20 μm powder by gas atomization. Transfer magnesium alloy B into a spoon and heat it to obtain a slurry with a temperature 10°C above the liquidus.

[0052] 0.5 kg of the above-mentioned powder was added to the flow channel of the heat removal device. The heat removal device with exhaust holes (aperture of 100 μm) on the surface was placed in the crucible, with the lower end of the heat removal device 2 mm away from the bottom of the container. The gas source was started to allow argon gas to enter the flow channel at a gas flow rate of 1 L / min. The ultrasonic horn arranged in the flow channel was also started with an ultrasonic power of 1 kW and an ultrasonic frequency of 10 kHz. When the temperature of the magnesium alloy slurry dropped to 5°C above the liquidus, a semi-solid magnesium alloy material was obtained.

[0053] Example 6: Composition of magnesium alloy A: 9% aluminum, 0.45% zinc, 0.17% manganese, 0.03% silicon, 0.01% copper, 0.001% nickel, 0.06% iron, and the balance being magnesium.

[0054] The composition of magnesium alloy B is: 9% aluminum, 0.45% zinc, 0.17% manganese, 0.03% silicon, 0.01% copper, 0.001% nickel, 0.002% iron, 0.9% Sr, and the balance is magnesium.

[0055] Prepare 1 kg of magnesium alloy A and 10 kg of magnesium alloy B. Prepare magnesium alloy A into 20 μm powder by gas atomization. Transfer magnesium alloy B into a spoon and heat it to obtain a slurry with a temperature 10°C above the liquidus.

[0056] 0.5 kg of the above-mentioned powder was added to the flow channel of the heat removal device. The heat removal device with exhaust holes (aperture of 100 μm) on the surface was placed in the crucible, with the lower end of the heat removal device 2 mm away from the bottom of the container. The gas source was started to allow argon gas to enter the flow channel at a gas flow rate of 5 L / min, and the ultrasonic horn arranged in the flow channel was started with an ultrasonic power of 1 kW and an ultrasonic frequency of 10 kHz. When the temperature of the magnesium alloy slurry dropped to 5°C above the liquidus, a semi-solid magnesium alloy material was obtained.

[0057] Comparative Example 1: Composition of magnesium alloy B: 9% aluminum, 0.45% zinc, 0.17% manganese, 0.03% silicon, 0.01% copper, 0.001% nickel, 0.002% iron, 0.3% Sr, and the balance is magnesium. The composition of magnesium alloy A is consistent with that of magnesium alloy B.

[0058] 1 kg of magnesium alloy A and 10 kg of magnesium alloy B were prepared. Magnesium alloy A was prepared into 20 μm powder by gas atomization. Magnesium alloy B was transferred into a spoon and heated to obtain a slurry with a temperature 10° C. higher than the liquidus line.

[0059] 0.5 kg of the above-mentioned powder was added to the flow channel of the heat removal device. The heat removal device with exhaust holes (aperture of 100 μm) on the surface was placed in the crucible, with the lower end of the heat removal device 2 mm away from the bottom of the container. The gas source was started to allow argon gas to enter the flow channel at a gas flow rate of 5 L / min, and the ultrasonic horn arranged in the flow channel was started with an ultrasonic power of 1 kW and an ultrasonic frequency of 10 kHz. When the temperature of the magnesium alloy slurry dropped to 5°C above the liquidus, a semi-solid magnesium alloy material was obtained.

[0060] Comparative Example 2: Composition of magnesium alloy A: 9% aluminum, 0.45% zinc, 0.17% manganese, 0.03% silicon, 0.01% copper, 0.001% nickel, 0.06% iron, 0.3% Sr, and the balance being magnesium.

[0061] The composition of magnesium alloy B is the same as that of magnesium alloy A.

[0062] 1 kg of magnesium alloy A and 10 kg of magnesium alloy B were prepared. Magnesium alloy A was prepared into 20 μm powder by gas atomization. Magnesium alloy B was transferred into a spoon and heated to obtain a slurry with a temperature 10° C. higher than the liquidus line.

[0063] 0.5 kg of the above-mentioned powder was added to the flow channel of the heat removal device. The heat removal device with exhaust holes (aperture of 100 μm) on the surface was placed in the crucible, with the lower end of the heat removal device 2 mm away from the bottom of the container. The gas source was started to allow argon gas to enter the flow channel at a gas flow rate of 5 L / min, and the ultrasonic horn arranged in the flow channel was started with an ultrasonic power of 1 kW and an ultrasonic frequency of 10 kHz. When the temperature of the magnesium alloy slurry dropped to 5°C above the liquidus, a semi-solid magnesium alloy material was obtained.

[0064] Tensile strength test method: The semi-solid magnesium alloy material was prepared into a plate with a thickness of 5 mm, and the test was performed in accordance with the national standard GB / T228.1-2010 "Tensile testing of metallic materials - Part 1: Room temperature test method", and the data were recorded in Table 1.

[0065] In vitro biodegradability test method: Using simulated body fluid (Article No. MG6615, Maiji Biotechnology, with a composition similar to human body fluid) as the test medium, 15 cm * 6 cm * 0.3 cm specimens (dry weight 49.1 g) were processed from the semi-solid magnesium alloy materials of the above-mentioned embodiment and comparative example. Among them, part of the specimen of comparative example 2 was electrochemically nickel-plated to form a 5 μm nickel layer on the surface as comparative example 3. The specimen was immersed in 200 mL of simulated body fluid at a constant temperature of 37°C. The simulated body fluid was replaced every 24 hours. The dry weight of the specimen was weighed and recorded after 20 days, and the time required for complete degradation of the specimen was recorded.

[0066] Table 1 Test results of tensile strength and in vitro biodegradability of Examples 1-6 and Comparative Examples 1-3.

[0067] According to the data in Table 1, compared with Comparative Example 1, the samples of Examples 1-6 have a lower corrosion rate in the early stage of the in vitro biodegradation performance test. This is because the present solution uses magnesium alloy A as an external particle to provide a nucleation core, and the slurry of magnesium alloy B grows around the external particle to form grains. On the one hand, magnesium alloy A provides a large number of heterogeneous nuclei, resulting in refined grains, such as Figure 1 The casting of Example 1 has refined grains, which improves the corrosion resistance of the grains. Furthermore, the low Fe concentration at the grain surface and intergranular spaces provides high corrosion resistance, reducing the corrosion rate of the magnesium alloy casting during early use and preventing the core grains from being exposed to body fluids. Compared to Comparative Example 2, the samples of Examples 1-6 show a shorter time to complete degradation. This is because the core grains of the materials of Examples 1-6 have a higher Fe concentration. After a period of continuous use, magnesium alloy castings made of these materials gradually corrode the grain surface and intergranular spaces. Exposure of the core grains to body fluids allows Fe and Mg to act as galvanic cells, increasing the corrosion rate of the magnesium alloy. As a result, these magnesium alloys not only exhibit a lower corrosion rate in the early stages, preventing rapid strength loss in the magnesium alloy casting, but also exhibit a higher corrosion rate in the later stages, preventing impact on bone healing. Figure 2 Figures A and C show the surface corrosion conditions of the samples of Example 1 and Comparative Example 1 at 0 days and 30 days in the in vitro biodegradability test, respectively. Figures A and C show the states of the samples of Comparative Example 1 and Example 1 at 0 days, respectively. Figures B and D show the states of the samples of Comparative Example 1 and Example 1 at 30 days, respectively. It can be seen that at 30 days, more severe corrosion occurred on the surface of Example 1, indicating that its corrosion rate at 30 days was significantly faster than that of Comparative Example 1. Compared with Example 1, the dry weight of Comparative Example 3 at 20d is not significantly reduced. This is because the surface of the casting is coated with a 5μm nickel layer. Nickel plating can improve the corrosion resistance of the magnesium alloy casting. However, its complete degradation time is significantly shorter than that of Example 1. This is because after the surface coating of Comparative Example 4 corrodes, the internal magnesium alloy will corrode rapidly and continue to accelerate. If used as a medical device material, it may exceed the tolerance of the human body. Although the corrosion time of the surface nickel layer can be extended by changing the thickness of the nickel layer, once the surface nickel layer corrodes, the internal magnesium alloy will still corrode rapidly and continue to accelerate. Therefore, directly coating the corrosion-resistant layer on the casting will lead to the problem of excessive corrosion rate in the later stage of corrosion.

[0068] Compared to Example 1, Example 2 reached complete degradation more slowly. This is because the lower iron content of magnesium alloy A results in a weaker galvanic effect when the core of the grains is exposed. Example 3 achieved a lower dry weight at 30 days compared to Example 1. This is because magnesium alloy B contains a higher concentration of iron, which affects its corrosion resistance and further shortens its complete degradation time. In Example 4, both magnesium alloys A and B use lower aluminum contents. This lower aluminum content reduces the formation of β phase, thereby improving corrosion resistance. Furthermore, magnesium alloy B contains a higher content of manganese, which can form a composite phase with iron to reduce the galvanic effect between iron and magnesium. Therefore, Example 4 achieved a higher dry weight at 30 days and a longer complete degradation time compared to Example 1. Example 5 uses a composite modifier in magnesium alloy B, which further refines the grains, which in turn inhibits corrosion. Example 6 uses a higher concentration of Sr in magnesium alloy B, which produces more Al4Sr phase, thereby improving the corrosion resistance of the casting.

[0069] The technical features of the above-mentioned embodiments can be combined arbitrarily. In order to make the description concise, not all possible combinations of the technical features in the above-mentioned embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0070] The above-described embodiments merely represent several implementation methods of the present invention, and their descriptions are relatively specific and detailed, but they should not be construed as limiting the scope of the patent for the invention. It should be noted that, for those skilled in the art, several variations and improvements can be made without departing from the concept of the present invention, and these all fall within the scope of protection of the present invention. Therefore, the scope of protection of the patent for the present invention shall be based on the attached claims.

Claims

1. A method for preparing a semi-solid alloy material for medical devices, characterized in that: The preparation method of the semi-solid alloy, The following steps are included: Magnesium alloy A and magnesium alloy B are prepared, wherein the magnesium alloy A is prepared into a 20-50 μm powder by gas atomization, and the magnesium alloy B is transferred into a container and heated to obtain a slurry having a temperature 10-20° C. above the liquidus line, wherein the mass fraction of iron in the magnesium alloy A is 0.02-0.06%, and the mass fraction of iron in the magnesium alloy B is 0-0.004%. A heat removal device with exhaust holes on its surface is placed in the container, wherein the heat removal device is provided with a flow channel for conveying gas and powder, and an acceleration device for accelerating the powder is provided in the flow channel. The gas and the powder are fed into the flow channel, wherein the mass of the powder is 0.01-0.05 times the mass of the slurry, the gas flow rate is 1-10 L / min, and the gas is argon. The acceleration device is activated so that the gas and the powder flow out of the exhaust hole and enter the slurry. When the temperature of the slurry is reduced to no more than 5° C. above the liquidus, the semi-solid alloy material is obtained. The magnesium alloy A comprises, by weight, 8.5% aluminum, 0.45-0.90% zinc, 0.17% manganese, 0-0.05% silicon, 0-0.025% copper, 0-0.001% nickel, 0.02-0.06% iron, and the balance being magnesium. The mass fraction of manganese in the magnesium alloy B is 0.4%, and the magnesium alloy B contains at least one element selected from the group consisting of B, Ca, and Sr.

2. The preparation method according to claim 1, characterized in that The mass fraction of iron in the magnesium alloy A is 0.04%.

3. The preparation method according to claim 1, characterized in that The magnesium alloy B contains Sr in an amount of 0.3-0.9% by mass.

4. The preparation method according to claim 1, characterized in that The magnesium alloy B is AZ91D.

5. The preparation method according to claim 1, characterized in that The ratio of the powder particle size to the exhaust hole diameter is 1:(2-5).

6. The preparation method according to claim 1, characterized in that The acceleration device is an ultrasonic horn with an ultrasonic power of 1-3 kW and an ultrasonic frequency of 10-30 kHz.

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