High-performance medical magnesium alloy micro-pipe and preparation method thereof

Abstract

The application discloses a high-performance medical magnesium alloy micro-pipe and a preparation method thereof, and belongs to the field of metal materials and processing technology.The magnesium alloy micro-pipe is prepared through certain alloy component proportioning, smelting technology and some key processing parameters, such as extrusion-drawing combined processing parameters (speed, temperature and deformation ratio, etc.), the component of the alloy is Mg-Zn-Ca-X, the mass percentage content of the Zn element is 0-4 wt.%, the mass percentage content of the Ca element is 0-1 wt.%, the X element is Mn / Sn / Sr / Si, the mass percentage content of the X element is 0-1 wt.%, and the balance is Mg.Under the condition of the application, the magnesium alloy micro-pipe material with a diameter of 2-6 mm and a wall thickness of 0.1-0.2 mm can be obtained through component design and corresponding extrusion-drawing combined processing technology, the mechanical property of the magnesium alloy micro-pipe material can reach 300-450 MPa, and the elongation rate can reach 15-30%, thereby providing technical support for the development and preparation of a blood vessel stent.

Description

TECHNICAL FIELD

[0001] The present application belongs to the field of biomedical metal materials, and particularly relates to a novel high-performance medical magnesium alloy micro-pipe and a preparation technique thereof. BACKGROUND

[0002] Coronary heart disease is a kind of cardio-cerebral vascular disease that is prone to occur in middle-aged and old people, and the harm of coronary heart disease is great, which can easily cause various serious symptoms and also can lead to various complications. The most effective treatment method for coronary heart disease is vascular stent implantation. As a cardiovascular stent material, magnesium alloy has the following outstanding advantages: (1) Magnesium is a trace element necessary for the human body, and is the fourth most abundant metal element in the human body and the second most abundant cation in cells next to K. Using magnesium alloy as an implanted stent material not only does not need to consider the toxicity of trace metal ions to cells, but also the release of magnesium ions in the implanted material is beneficial to the human body. (2) Good tissue compatibility, low embolism and low inflammatory reaction. (3) Magnesium alloy biomaterials have a price advantage. Magnesium is the most abundant metal element on the earth's surface including the ocean, and is low in price. (4) Magnesium has a low standard equilibrium potential, and has a natural advantage as a degradable material. (5) The magnesium alloy stent is completely degraded and absorbed by the blood vessels at the original stent site, and a calcium-phosphorus compound is formed at the corresponding site. When the stent is completely degraded, it can still be identified and found by IUS and CT imaging methods, which is beneficial to clinical follow-up examination.

[0003] According to the deformation characteristics of magnesium alloy, a new magnesium alloy micro-pipe forming technology is invented, and a large-length-diameter ratio thin-walled pipe with high size precision is prepared. The plastic deformation mechanism of the pipe material is studied by using optical microscope (OM), electron backscatter diffraction technology (EBSD) and universal material testing machine. The pipe material is subjected to Hank's simulated body fluid immersion experiment, and the corrosion behavior is studied by using scanning electron microscope (SEM), X-ray diffractometer (XRD) and electrochemical workstation. The vascular stent product is processed by laser engraving, and the independent design and processing of the vascular stent are realized.

[0004] At present, the coronary stent material used in clinical medicine is mainly high polymer material and medical metal material. High polymer material is favored by people in the early stage of stent application due to its excellent biocompatibility, flexibility and easy processing forming. However, the mechanical properties of high polymer material are not as good as metal material, the radial support force is not enough, and the breakage is easy to occur, which causes potential harm to the human body. The medical metal materials mainly include stainless steel, cobalt-nickel alloy, titanium alloy and shape memory alloy. The mechanical properties of these metal materials are better than those of high polymer materials, which can provide sufficient radial support force to open the occluded blood vessels and ensure blood circulation. However, these materials are not perfect and have some shortcomings. First, these alloys are inert metals and cannot be degraded, so secondary removal is needed after operation, which increases the pain and medical cost of patients; second, the biocompatibility of these materials is poor, which can cause damage to the blood vessel wall, stimulate the proliferation of vascular tissue cells and cause thrombosis, thereby causing blood vessel restenosis and harm to the human body. Therefore, it is of great significance to develop new medical metal materials with good mechanical properties and biocompatibility and capable of degrading in vivo.

[0005] Biomedical materials, as the most potential sunrise industry, have huge economic benefits and are supported by various countries. People pay great attention to the development of biomedical material science and industrial application, and biomedical materials have become the research focus of researchers in various countries. With the continuous deepening of research, the medical application performance of magnesium alloy has been gradually explored by people, and more and more researchers have participated in the research in this field. As the most promising degradable implant material in the 21st century, in recent years, biomedical magnesium alloy has attracted widespread attention at home and abroad. At present, many international companies have developed degradable magnesium alloy implant products, including plates, rods, tubes, porous foams, composite materials, bone nails and vascular stents in various forms, which fully show the good processing forming performance and application potential of magnesium alloy medical products. This research has great significance for the later research and clinical application of magnesium alloy vascular stents. SUMMARY

[0006] The problem to be solved by the present application is how to improve the forming performance of magnesium alloy micro-pipe material, which is mainly realized by alloying design and forming technology innovation. A variety of non-toxic and harmless alloying elements are used, and an alloy product with Zn and Ca as main alloying elements and meeting certain doping ratio requirements is designed according to the performance requirements of the product, and low alloying element X is used to realize the fine adjustment of the alloy in the deformation mechanism, so that the material can be processed by extrusion-drawing composite process at a lower temperature, avoiding the defects of significant work hardening and easy cracking of the product, thereby obtaining a micro-pipe product with controllable wall thickness, controllable inner diameter and accurate size at a lower temperature.

[0007] The application discloses a high-performance medical magnesium alloy micro-pipe, characterized by a material composition of Mg, Zn, Ca, X and the like, wherein X is one or more than two of Mn, Sn, Sr and Si, and the total alloying element (Zn, Ca, X and the like) in the alloy is less than or equal to 6 wt.%.

[0008] Further, the trace element X is less than or equal to 1 wt.%, the content of the Zn element is 0-4 wt.% and the content of the Ca element is 0-1 wt.%, and neither the Zn nor the Ca is 0, and the ratio of Zn / Ca (wt.%) is within the range of 0.5-4.0.

[0009] The pipe is prepared by adopting an extrusion-drawing combined plastic processing technology, and the preparation method specifically comprises the following steps:

[0010] (1) a melting process

[0011] Firstly, the surfaces of prepared Mg, Mg-Ca, Mg-Mn, Mg-Sr, Mg-Si and the like are cleaned to remove the oxide scales and other impurities, then the small blocks are segmented and placed in an electric resistance melting furnace with a temperature of 700-780 DEG C for heat preservation, after the alloying is completed, the alloy is stirred uniformly, and after 10-25 min of static placement, the furnace temperature is increased to 700-780 DEG C again, heat preservation is performed for 5-10 min, the power of the heating furnace is turned off, and after the temperature is stabilized, the alloy is poured into a common low-carbon steel mold; the prepared alloy is subjected to solid solution treatment, the solid solution treatment temperature is 350-450 DEG C, and after heat preservation for 5-25 h, the coarse eutectic phase in the alloy is dissolved, so that a supersaturated solid solution is obtained;

[0012] (2) an extrusion process

[0013] The once-formed fine pipe magnesium alloy has a diameter of 6-10 mm and a wall thickness of 0.2-0.3 mm, has no welding seam and is formed in a body; the hot extrusion temperature is 200-350 DEG C, the extrusion ratio is 25-40, and the extrusion rate is greater than or equal to 15 m / min; after the extrusion, low-temperature heat preservation is performed in a heat preservation box, the heat preservation temperature is 50-150 DEG C, the heat preservation time is less than or equal to 60 min, and then oil quenching is performed.

[0014] The magnesium alloy has poor plastic deformation capacity and is sensitive to the processing temperature between 300 DEG C and 450 DEG C; when the temperature is low, it is difficult to open the slip system in the crystal, the plasticity is poor, and the deformation is difficult; when the temperature is high, the magnesium alloy will be cracked during the extrusion, it is difficult to be formed, and the pipe material has coarse structure and poor surface quality. In the application, the hot extrusion temperature is 200-350 DEG C, the extrusion ratio is 25-40, and the extrusion rate is greater than or equal to 15 m / min; during the extrusion process, the temperature of the billet will be increased due to friction and deformation work, therefore, during the heating, the temperature of the mold should be slightly lower than that of the billet.

[0015] (3) a drawing process

[0016] The pipe material of step (2) is drawn, the drawing process is a rapid and efficient forming drawing process, the drawing speed is 0.1-10mm / min, the drawing process is less than 10 times (empty drawing + long core rod), the drawing temperature is 150-250 DEG C, the final product diameter is 2-6mm, the wall thickness is 0.1-0.2mm, and the product wall thickness precision is ±0.01mm.

[0017] The factors affecting the change of the wall thickness of the pipe material during empty drawing are mainly: relative wall thickness, material, state, processing pass, lubrication condition and drawing speed. Through experiments, it can be obtained that the wall thickening phenomenon during the drawing process of the thin-walled pipe can be effectively controlled by increasing the drawing pass number and reducing the pass processing rate. The influence of the drawing speed on the wall thickness change. When the relative wall thickness is small, the pipe material has a wall thickening phenomenon during empty drawing at different speeds. With the increase of the speed, the relative stress during drawing increases gradually, so that the increment during the empty drawing process increases obviously, so that the wall thickness of the pipe material is the thickest when the speed is 0.3mm / s. It can be obtained that the speed of empty drawing should not be too fast, which will make the wall of the final pipe material too thick. The long core rod drawing can effectively eliminate the wall thickening phenomenon during the subsequent drawing pass process. In the long core rod drawing process, the friction does not hinder the drawing process, but helps to reduce the drawing force. Under the condition that other conditions are the same, the drawing force required for long core rod drawing decreases obviously. The drawing speed is 0.1-10mm / min, the drawing process is less than 10 times (empty drawing + long core rod), the drawing temperature is 150-250 DEG C, the final product diameter is 2-6mm, the wall thickness is 0.1-0.2mm, and the product wall thickness precision is high (±0.01mm).

[0018] The mechanical properties of the product can reach 300-450MPa, and the elongation can reach 15-40%. It can be used for the production of heart blood

[0019] Vessel, cerebral blood vessel, renal artery blood vessel, lower limb artery blood vessel and gallbladder blood vessel interventional therapy stent instrument. The substantial characteristics and significant progress of the present application

[0020] (1) The alloy composition design is innovated, and elements beneficial to the human body are added, so that the pipe forming efficiency is higher.

[0021] (2) One extrusion and two drawing compound forming are adopted, and the forming process is simple and efficient.

[0022] (3) The specification of the micro-pipe product can be adjusted, and various caliber pipe materials can be prepared according to the needs.

[0023] (4) The preparation and processing method of the alloy is simple, and high-quality and exquisite medical magnesium alloy micro-pipe can be obtained without special equipment and method, which saves the cost.

[0024] (5) The product has excellent mechanical properties and can be used to produce various types (cardiovascular, cerebrovascular, renal artery blood vessels, lower limb artery blood vessels and gallbladder blood vessels) of vascular stent products. DETAILED DESCRIPTION

[0025] The application will be further described in conjunction with the following examples, but the application is not limited to the following examples.

[0026] Example 1

[0027] The magnesium ingot with a purity of 99.95wt.%, zinc ingot with a purity of 99.99wt.% and Mg-9.4wt.% Ca intermediate alloy were used as raw materials, and were melted in a resistance furnace under the protection of 1:100 SF6 and N2 mixed gas. The furnace temperature was adjusted to 700℃, and after the magnesium ingot was melted, the Mg-Ca intermediate alloy and the zinc ingot were added in sequence, and the time interval for adding the intermediate alloy each time was 10 min. After all the alloys were added, the mechanical stirring was performed for 5 min, and then the molten metal liquid was poured into a metal mold (preheated at 200℃) after being placed for 10 min, so as to obtain the Mg-0.5Zn-1Ca alloy with a certain composition, which was then subjected to solid solution treatment at 350℃ for 5 h. Subsequently, the sample was subjected to extrusion, and the extrusion temperature was 200℃, the extrusion ratio was 25, the extrusion rate was 15 mm / min, the extrusion pipe product had an inner diameter of 10 mm and a wall thickness of 0.3 mm. Then, the above extruded product was subjected to heat preservation treatment, and the heat preservation temperature was 50℃ and the heat preservation time was 1 h. The extruded pipe product after heat preservation was subjected to drawing treatment, and the drawing process was 2 passes of empty drawing + 6 passes of long mandrel drawing, the drawing speed was 10 mm / min, the drawing temperature was 250℃, the final micro-pipe product had a diameter of 6 mm and a wall thickness of 0.2 mm, the strength of the product was 300 MPa, the elongation was 15%, and the human body simulated body fluid immersion corrosion rate was 0.15 mm / y.

[0028] Example 2

[0029] The Mg ingot with purity of 99.95wt.%, Zn ingot with purity of 99.99wt.%, Mg-5.0wt.%Mn master alloy, Mg-9.4wt.%Ca master alloy were used as raw materials, and were melted in a resistance furnace under the protection of 1:100 mixed gas of SF6 and N2. The furnace temperature was adjusted to 700℃, and after the Mg ingot was melted, the Mg-Ca master alloy, Mg-Mn master alloy, Mg-Sn master alloy and Zn ingot were added in sequence, and the time interval for adding each master alloy was 10 min. After all the master alloys were added, the molten metal was mechanically stirred for 5 min and then was left to stand for 10 min, and then the molten metal was poured into a metal mold (preheated to 200℃) to obtain the Mg-0.5Zn-1Ca-0.2Mn alloy with the specified composition, which was then subjected to solid solution treatment at 360℃ for 5 h. Subsequently, the sample was subjected to extrusion at an extrusion temperature of 220℃, an extrusion ratio of 25 and an extrusion rate of 15 mm / min, and the extruded product had an inner diameter of 8 mm and a wall thickness of 0.2 mm. Then, the extruded product was subjected to heat preservation treatment at a heat preservation temperature of 100℃ for 35 min. The heat preserved extruded product was then subjected to drawing treatment, and the drawing process was 2 passes of air drawing + 4 passes of long mandrel drawing, the drawing speed was 5 mm / min, the drawing temperature was 200℃, the final micro-tube product had a diameter of 4 mm and a wall thickness of 0.2 mm, the strength of the product was 350 MPa, the elongation was 18%, and the immersion corrosion rate in human body simulation fluid was 0.2 mm / y.

[0030] Example 3

[0031] The magnesium ingot with purity of 99.95wt.%, zinc ingot with purity of 99.99wt.%, Mg-5.0wt.%Mn master alloy, Mg-9.4wt.%Ca master alloy, Mg-30wt.%Sn master alloy were used as raw materials, and were melted in a resistance furnace under the protection of 1:100 mixed gas of SF6 and N2. The furnace temperature was adjusted to 700℃, and after the magnesium ingot was melted, the Mg-Ca master alloy, Mg-Mn master alloy, Mg-Sn master alloy and zinc ingot were added in sequence, and the time interval for adding each master alloy was 10 min. After all the master alloys were added, the molten metal was mechanically stirred for 5 min and then was left for 10 min, and then the molten metal was poured into a metal mold (preheated at 200℃) to obtain the Mg-0.5Zn-1Ca-0.2Mn-0.3Sn alloy with the specified composition, which was then subjected to solid solution treatment at 360℃ for 5 h. Subsequently, the sample was subjected to extrusion at an extrusion temperature of 220℃, an extrusion ratio of 30 and an extrusion rate of 20 mm / min, and the extruded product had an inner diameter of 6 mm and a wall thickness of 0.2 mm. Then, the extruded product was subjected to heat preservation treatment at a heat preservation temperature of 120℃ for 45 min. The heat preserved extruded product was then subjected to drawing treatment, and the drawing process was 3 passes of air drawing + 3 passes of long mandrel drawing, the drawing speed was 10 mm / min, the drawing temperature was 250℃, the final micro-pipe product had a diameter of 2 mm and a wall thickness of 0.1 mm, the strength of the product was 400 MPa, the elongation was 35%, and the immersion corrosion rate in human body simulation fluid was 0.3 mm / y.

[0032] Example 4

[0033] The magnesium ingot with purity of 99.95wt.%, zinc ingot with purity of 99.99wt.%, Mg-5.0wt.%Mn master alloy, Mg-9.4wt.%Ca master alloy, Mg-30wt.%Sn master alloy, Mg-5wt.%Si master alloy were used as raw materials, and were melted in a resistance furnace under the protection of 1:100 mixed gas of SF6 and N2. The furnace temperature was adjusted to 700°C. After the magnesium ingot was melted, the Mg-Ca master alloy, Mg-Mn master alloy, Mg-Sn master alloy, Mg-Si master alloy and zinc ingot were added in sequence, and the time interval for adding each master alloy was 10 min. After all the master alloys were added, the molten metal was mechanically stirred for 5 min and then statically placed for 10 min. Then, the molten metal was poured into a metal mold (preheated at 200°C) to obtain the Mg-0.5Zn-1Ca-0.2Mn-0.3Sn-0.2Si alloy with the specified composition, which was then subjected to solid solution treatment at 360°C for 5 h. Subsequently, the sample was extruded at an extrusion temperature of 300°C, an extrusion ratio of 40 and an extrusion rate of 30 mm / min, and the extruded product had an inner diameter of 7 mm and a wall thickness of 0.3 mm. Then, the extruded product was subjected to heat preservation treatment at a heat preservation temperature of 150°C for 60 min. The heat-preserved extruded product was then drawn, and the drawing process included 4 passes of air drawing and 5 passes of long mandrel drawing, the drawing speed was 5 mm / min, the drawing temperature was 175°C, the final micro-pipe product had a diameter of 4 mm and a wall thickness of 0.2 mm, the strength of the product was 385 MPa, the elongation was 15%, and the immersion corrosion rate in human body simulation fluid was 0.29 mm / y.

[0034] Example 5

[0035] The Mg ingot with purity of 99.95wt.%, Zn ingot with purity of 99.99wt.%, Mg-5.0wt.%Mn master alloy, Mg-9.4wt.%Ca master alloy, Mg-30wt.%Sn master alloy were used as raw materials, and were melted in a resistance furnace under the protection of 1:100 mixed gas of SF6 and N2. The furnace temperature was adjusted to 700℃, and after the Mg ingot was melted, the Mg-Ca master alloy, Mg-Mn master alloy, Mg-Sn master alloy, and Zn ingot were added in sequence, and the time interval for adding each master alloy was 10 min. After all the master alloys were added, the molten metal was mechanically stirred for 5 min, and then was left to stand for 10 min. Then, the molten metal was poured into a metal mold (preheated at 200℃) to obtain the Mg-Zn-0.5Ca-0.2Mn-0.4Sn alloy with the specified composition, and was subjected to solid solution treatment at 360℃ for 5 h. Subsequently, the sample was subjected to extrusion at an extrusion temperature of 220℃, an extrusion ratio of 30, and an extrusion rate of 20 mm / min, and an extruded product with an inner diameter of 6 mm and a wall thickness of 0.2 mm was obtained. Then, the extruded product was subjected to heat preservation treatment at a heat preservation temperature of 120℃ for 45 min. Then, the heat preserved extruded product was subjected to drawing treatment, and the drawing process was 4 passes of air drawing + 4 passes of long mandrel drawing, the drawing speed was 0.5 mm / min, the drawing temperature was 225℃, the diameter of the final micro tube product was 2 mm, the wall thickness was 0.1 mm, the strength of the product was 420 MPa, the elongation was 40%, and the immersion corrosion rate in human body simulation body fluid was 0.38 mm / y.

[0036] Example 6

[0037] The magnesium ingot with purity of 99.95wt.%, zinc ingot with purity of 99.99wt.%, Mg-5.0wt.%Mn master alloy, Mg-9.4wt.%Ca master alloy, Mg-30wt.%Sn master alloy, etc. are used as raw materials, and are melted in a resistance furnace under the protection of 1:100 mixed gas of SF6 and N2. The furnace temperature is adjusted to 700℃, after the magnesium ingot is melted, the Mg-Ca master alloy, Mg-Mn master alloy, Mg-Sn master alloy, zinc ingot are added in sequence, and the time interval for each addition of master alloy is 10 min. After all the alloys are added, the molten metal is mechanically stirred for 5 min and then is left for 10 min, and then the molten metal is poured into a metal mold (preheated at 200℃) to obtain the Mg-3Zn-1Ca-0.2Mn-0.2Sn alloy with the specified composition, which is then subjected to solid solution treatment at 360℃ for 5 h. Subsequently, the sample is subjected to extrusion at an extrusion temperature of 350℃, an extrusion ratio of 25, and an extrusion rate of 40 mm / min, and the extruded product has an inner diameter of 10 mm and a wall thickness of 0.3 mm. Then, the extruded product is subjected to heat preservation treatment at a heat preservation temperature of 150℃ for 45 min. The heat preserved extruded product is then subjected to drawing treatment, and the drawing process is 2 passes of air drawing + 6 passes of long mandrel drawing, a drawing speed of 2 / min, and a drawing temperature of 225℃. The final micro-pipe product has a diameter of 3 mm and a wall thickness of 0.1 mm, and the product has a strength of 412 MPa, an elongation of 33%, and a human body simulated body fluid immersion corrosion rate of 0.42 mm / y.

[0038] Example 7

[0039] The magnesium ingot with purity of 99.95wt.%, zinc ingot with purity of 99.99wt.%, Mg-5.0wt.%Mn master alloy, Mg-9.4wt.%Ca master alloy, Mg-30wt.%Sn master alloy were used as raw materials, and were melted in a resistance furnace under the protection of 1:100 mixed gas of SF6 and N2. The furnace temperature was adjusted to 700℃, and after the magnesium ingot was melted, the Mg-Ca master alloy, Mg-Mn master alloy, Mg-Sn master alloy, and zinc ingot were sequentially added, and the time interval for each addition of master alloy was 10 min. After all the master alloys were added, the molten metal was mechanically stirred for 5 min and then statically placed for 10 min, and then the molten metal was poured into a metal mold (preheated to 200℃) to obtain the Mg-4Zn-1Ca-0.2Mn-0.6Sn alloy with the specified composition, which was then subjected to solid solution treatment at 360℃ for 5 h. Subsequently, the sample was subjected to extrusion at an extrusion temperature of 320℃, an extrusion ratio of 40, and an extrusion rate of 20 mm / min, and the extruded product had an inner diameter of 9 mm and a wall thickness of 0.2 mm. Then, the extruded product was subjected to heat preservation treatment at a heat preservation temperature of 100℃ for 35 min. The heat preserved extruded product was then subjected to drawing treatment, and the drawing process was 2 passes of air drawing + 5 passes of long mandrel drawing, the drawing speed was 5 mm / min, the drawing temperature was 220℃, the final micro-pipe product had a diameter of 4 mm and a wall thickness of 0.1 mm, the strength of the product was 378 MPa, the elongation was 22%, and the immersion corrosion rate in human body simulation fluid was 0.45 mm / y.

[0040] Example 8

[0041] The Mg ingot with purity of 99.95wt.%, Zn ingot with purity of 99.99wt.%, Mg-5.0wt.%Mn master alloy, Mg-9.4wt.%Ca master alloy, Mg-30wt.%Sn master alloy and Mg-5wt.%Si master alloy were used as raw materials, and were melted in a resistance furnace under the protection of 1:100 mixed gas of SF6 and N2. The furnace temperature was adjusted to 700°C, and after the Mg ingot was melted, the Mg-Ca master alloy, Mg-Mn master alloy and Mg-Sn master alloy were added in sequence, and the Zn ingot was added. The time interval for adding each master alloy was 10 min. After all the master alloys were added, the molten metal was mechanically stirred for 5 min, and then was left to stand for 10 min. Then, the molten metal was poured into a metal mold (preheated at 200°C) to obtain the Mg-4Zn-1Ca-0.2Mn-0.3Sn-0.2Si alloy with a predetermined composition, and the alloy was subjected to solid solution treatment at 360°C for 5 h. Subsequently, the sample was subjected to extrusion at an extrusion temperature of 220°C, an extrusion ratio of 30 and an extrusion rate of 20 mm / min, and an extruded pipe product with an inner diameter of 6 mm and a wall thickness of 0.2 mm was obtained. Then, the extruded pipe product was subjected to heat preservation treatment at a heat preservation temperature of 120°C for 45 min. The heat preserved extruded pipe product was subjected to drawing treatment, and the drawing process was 3 passes of air drawing + 3 passes of long mandrel drawing at a drawing speed of 10 mm / min and a drawing temperature of 250°C. The final micro-pipe product had a diameter of 2 mm, a wall thickness of 0.1 mm, a strength of 430 MPa, an elongation of 35%, and a human body simulated body fluid immersion corrosion rate of 0.51 mm / y.

[0042] Example 9

[0043] The Mg ingot with purity of 99.95wt.%, Zn ingot with purity of 99.99wt.%, Mg-5.0wt.%Mn master alloy, Mg-9.4wt.%Ca master alloy, Mg-30wt.%Sn master alloy, Mg-5wt.%Si master alloy and Mg-5wt.%Sr master alloy were used as raw materials, and were melted in a resistance furnace under the protection of 1:100 mixed gas of SF6 and N2. The furnace temperature was adjusted to 700℃, and after the Mg ingot was melted, the Mg-Ca master alloy, Mg-Mn master alloy and Mg-Sn master alloy were added in sequence, and the Zn ingot was added. The time interval for adding each master alloy was 10 min. After all the master alloys were added, the molten metal was mechanically stirred for 5 min, and then was left to stand for 10 min. Then, the molten metal was poured into a metal mold (preheated at 200℃) to obtain the Mg-4Zn-1Ca-0.2Mn-0.3Sn-0.2Si-0.2Sr alloy with a certain composition, and was subjected to solid solution treatment at 360℃ for 5 h. Subsequently, the sample was subjected to extrusion at an extrusion temperature of 220℃, an extrusion ratio of 30 and an extrusion rate of 20 mm / min, and an extruded pipe product with an inner diameter of 6 mm and a wall thickness of 0.2 mm was obtained. Then, the extruded pipe product was subjected to heat preservation treatment at a heat preservation temperature of 120℃ for 45 min. The heat preserved extruded pipe product was subjected to drawing treatment, and the drawing process was 3 passes of air drawing + 3 passes of long mandrel drawing, the drawing speed was 10 mm / min, the drawing temperature was 250℃, the diameter of the final micro pipe product was 2 mm, the wall thickness was 0.1 mm, the strength of the product was 450 MPa, the elongation was 35%, and the immersion corrosion rate in the human body simulation body fluid was 0.37 mm / y.

[0044] Example 10

[0045] The Mg ingot with purity of 99.95wt.%, Zn ingot with purity of 99.99wt.%, Mg-5.0wt.%Mn master alloy, Mg-9.4wt.%Ca master alloy, Mg-30wt.%Sn master alloy and Mg-5wt.%Sr master alloy were used as raw materials, and were melted in a resistance furnace under the protection of 1:100 mixed gas of SF6 and N2. The furnace temperature was adjusted to 700℃, and after the Mg ingot was melted, the Mg-Ca master alloy, Mg-Mn master alloy and Mg-Sn master alloy were added in sequence, and the Zn ingot was added. The time interval for adding each master alloy was 10 min. After all the master alloys were added, the molten metal was mechanically stirred for 5 min, and then was left to stand for 10 min. Then, the molten metal was poured into a metal mold (preheated at 200℃) to obtain the Mg-4Zn-1Ca-0.2Mn-0.3Sn-0.4Sr alloy with a certain composition, and was subjected to solid solution treatment at 360℃ for 5 h. Subsequently, the sample was subjected to extrusion at an extrusion temperature of 220℃, an extrusion ratio of 30 and an extrusion rate of 20 mm / min, and an extruded pipe product with an inner diameter of 6 mm and a wall thickness of 0.2 mm was obtained. Then, the extruded pipe product was subjected to heat preservation treatment at a heat preservation temperature of 120℃ for 45 min. The heat preserved extruded pipe product was subjected to drawing treatment, and the drawing process was 3 passes of air drawing + 5 passes of long mandrel drawing, the drawing speed was 10 mm / min, the drawing temperature was 250℃, the diameter of the final micro pipe product was 3 mm, the wall thickness was 0.1 mm, the strength of the product was 435 MPa, the elongation was 37%, and the immersion corrosion rate in human body simulation body fluid was 0.52 mm / y.

[0046] Although the preferred embodiments have been described in detail hereinabove, it should be apparent to those skilled in the art that various modifications, additions and substitutions are possible, without departing from the scope and spirit of the application as disclosed herein.

Claims

1. A method for preparing high-performance medical magnesium alloy microchannels, characterized in that, The material composition consists of Mg, Zn, Ca, and X elements, where X is one or more of Mn, Sn, Sr, and Si, and the total alloying elements Zn, Ca, and X added in the alloy are ≤6 wt.%; the addition of element X is less than or equal to 1 wt.%, the content of Zn element is 0-4 wt.%, the content of Ca element is 0-1 wt.%, and neither Zn nor Ca is 0, and the ratio of Zn / Ca (wt.%) is between 0.5 and 4.

0. Includes the following steps: (1) Smelting process First, the surfaces of the prepared Mg, Mg-Ca, Mg-Mn, Mg-Sr, and Mg-Si metals are cleaned to remove oxide scale and impurities. Then, they are cut into small pieces and placed at a temperature of 700~780°C. o The alloy is held at a constant temperature in a resistance melting furnace (C) until it melts. After melting, the mixture is stirred evenly and allowed to stand for 10-25 minutes. Then, the furnace temperature is raised back to 700-780°C. o C. Hold at this temperature for 5-10 minutes, then turn off the furnace power. After the temperature stabilizes, cast the alloy into a common low-carbon steel mold. Perform a solution treatment on the resulting alloy at a temperature of 350-450°C. o C, after holding at the temperature for 5~25h, the coarse eutectic phase in the alloy dissolves, thereby obtaining a supersaturated solid solution; (2) Extrusion process Hot extrusion temperature 200-350℃ o C, extrusion ratio 25-40, extrusion speed ≥15m / min; after extrusion, keep warm in an insulated box at a low temperature of 50-150°C. o C, the heat preservation time is less than or equal to 60 minutes, followed by oil quenching, and the one-time forming of fine pipe magnesium alloy with a diameter of 6-10 mm and a wall thickness of 0.2-0.3 mm, without weld seams, integrally formed; (3) Pulling process The tube from step (2) is drawn using a rapid and efficient forming drawing process. The drawing speed is 0.1-10 mm / min, and the drawing process consists of air drawing + long mandrel drawing, with a total of less than 10 passes. The drawing temperature is 150-250 °C. o C. The final product diameter is 2-6mm, the wall thickness is 0.1-0.2mm, and the product wall thickness accuracy is ±0.01mm.

2. The method according to claim 1, characterized in that, The elongation rate is 15-40%.

3. The application of the high-performance medical magnesium alloy microchannels obtained by the method of claim 1 or 2, for the production of interventional stent devices for cardiovascular, cerebral, renal, lower limb, and gallbladder vessels.