Molybdenum-based alloy and preparation method therefor, and medical implant device and preparation method therefor

Abstract

The present invention provides a molybdenum-based alloy and a preparation method therefor, and a medical implant device and a preparation method therefor. The molybdenum-based alloy comprises a molybdenum matrix, polydopamine, and an alloy element, wherein the alloy element comprises at least one of a strengthening-toughening alloy element and a purification alloy element, the strengthening-toughening alloy element comprises at least one of a tantalum element, an iridium element, and a platinum element, and the purification alloy element comprises at least one of a strontium element, a titanium element, and a cerium element. The medical implant device is made of the molybdenum-based alloy. The present invention can solve the problems of room-temperature brittleness and anisotropy of molybdenum-based alloys, thereby improving the comprehensive performance of the molybdenum-based alloys, guaranteeing that a medical implant device such as a vascular stent prepared from the molybdenum-based alloy provided by the present invention has excellent mechanical properties under an in vivo use temperature condition.

Description

Molybdenum-based alloy, preparation method thereof, medical implant device and preparation method thereof Technical Field

[0001] The present invention relates to the technical field of molybdenum-based alloy preparation, and in particular to a molybdenum-based alloy, a method for preparing the molybdenum-based alloy, a medical implant device and a method for preparing the same. Background Art

[0002] Coronary heart disease, a common and frequently occurring disease, has been steadily increasing in my country and has become one of the major diseases that endanger the physical and mental health of the Chinese people. Minimally invasive interventional therapy with stents is currently the main method for treating cardiovascular diseases. Currently used stents are mostly non-degradable, permanent metal stents. Due to drawbacks such as continuous mechanical traction and foreign body inflammatory reactions, they can easily lead to problems such as intimal hyperplasia, restenosis, and late thrombosis. To address the limitations of traditional metal stents, degradable metal vascular stents are being used to support the lumen for a certain period of time and gradually degrade and disappear after the vessel is remodeled. This has become the future development direction of vascular stents.

[0003] Degradable vascular stents currently under research include metals (Mg, Zn, Fe) and polymers. Magnesium alloy and polymer biodegradable stents have already been developed. However, these biodegradable stents exhibit significant drawbacks. For example, magnesium alloys degrade rapidly, failing to maintain mechanical integrity for three months, while iron alloys degrade slowly, failing to fully degrade within two years. Zinc's corrosion degradation rate is well-suited for clinical applications (20 μm / y), but its mechanical properties are poor, and it also suffers from "room-temperature aging" and "process softening." In terms of mechanical properties, magnesium alloys have low strength and poor ductility, while biodegradable polymers exhibit even poorer mechanical properties than metals and exhibit anisotropic properties. Regarding biosafety, magnesium alloys degrade rapidly, resulting in elevated pH at the implant site and the release of hydrogen, potentially leading to severe inflammatory reactions. The safety of rust, a degradation product of iron alloys, remains uncertain. Furthermore, magnesium alloys and polymers have inherent disadvantages regarding device X-ray visibility, increasing surgical difficulty and risk and compromising postoperative follow-up.

[0004] Molybdenum is an essential trace element for the human body, with adults requiring a daily intake of 0.15-0.5 mg. Molybdenum is a key component of numerous enzymes, plays a role in iron utilization, prevents anemia, promotes growth, and aids in the metabolism of carbohydrates and fats. It maintains myocardial energy metabolism and prevents Keshan disease. It also helps maintain arterial elasticity and prevent cardiovascular disease. It also supports immune function. Research from Fraunhofer IFAM in Germany and the University of Michigan in the United States has shown that molybdenum is biodegradable and degrades evenly at a moderate rate, approaching that of zinc alloys. Furthermore, molybdenum does not affect cell activity, nor does it cause thrombosis or inflammation. Both in vitro and in vivo animal studies have demonstrated its good biosafety.

[0005] Molybdenum and molybdenum-based alloys inherently exhibit a range of processing characteristics, including high deformation temperature, severe oxidation at high temperatures, high tensile strength, poor ductility, rapid temperature drop, and a sharp increase in tensile strength with decreasing temperature. Deforming molybdenum and molybdenum-based alloys is difficult due to their inherent processing characteristics, including high deformation temperature, severe oxidation at high temperatures, high tensile strength, poor plasticity, rapid temperature drop, and a sharp increase in tensile strength with decreasing temperature. In particular, existing molybdenum and molybdenum-based alloys suffer from two technical difficulties: low-temperature brittleness and relatively poor cross-sectional mechanical properties. This complicates the processing of molybdenum-based alloy medical devices near room temperature, severely limiting their application in medical devices. Therefore, it is necessary to develop a new, high-strength, tough, and biodegradable molybdenum-based alloy suitable for use near room temperature.

[0006] It should be noted that the information disclosed in the background technology section of the invention is only intended to deepen the understanding of the general background technology of the invention, and should not be regarded as an admission or any form of implication that the information constitutes prior art already known to those skilled in the art.

[0007] Summary of the Invention

[0008] The object of the present invention is to provide a molybdenum-based alloy, a method for preparing a molybdenum-based alloy, a medical implant device and a method for preparing the same, which can solve one or more of the above-mentioned technical problems.

[0009] In order to solve the above technical problems, the present invention provides a molybdenum-based alloy, comprising a molybdenum matrix, polydopamine and alloying elements, wherein the alloying elements include at least one of a strengthening alloying element and a purifying alloying element, wherein the strengthening alloying element includes at least one of tantalum, iridium and platinum; and the purifying alloying element includes at least one of strontium, titanium and cerium.

[0010] Optionally, the mass percentage of the strengthening and toughening alloying element in the molybdenum-based alloy is less than or equal to 20%.

[0011] Optionally, the mass percentage of the strengthening and toughening alloy element in the molybdenum-based alloy is 0.5% to 2%.

[0012] Optionally, the mass percentage of the purifying alloy element in the molybdenum-based alloy is less than or equal to 1.0%.

[0013] Optionally, the mass percentage of the purified alloy element in the molybdenum-based alloy is 0.01% to 0.04%.

[0014] Optionally, the mass percentage of the polydopamine in the molybdenum-based alloy is less than or equal to 1.5%.

[0015] Optionally, the mass percentage of the polydopamine in the molybdenum-based alloy is 0.1% to 0.3%.

[0016] Optionally, the mass percentage of impurity elements in the molybdenum-based alloy is less than or equal to 0.2%, and the impurity elements include at least one of chromium, copper, iron, nickel, tungsten, manganese, silicon, oxygen, nitrogen, carbon and hydrogen.

[0017] Optionally, the mass percentages of copper, iron and nickel in the molybdenum-based alloy are all less than 20 ppm; the mass percentage of carbon in the molybdenum-based alloy is less than or equal to 0.03%, the mass percentages of hydrogen, oxygen and nitrogen in the molybdenum-based alloy are all less than or equal to 0.02%; and the mass percentages of chromium, silicon, tungsten and manganese in the molybdenum-based alloy are all less than or equal to 0.05%.

[0018] Optionally, the molybdenum-based alloy does not contain any one of calcium, magnesium, sodium, sulfur, lead, bismuth, zinc, rhenium, yttrium, zirconium and tin.

[0019] To solve the above technical problems, the present invention further provides a method for preparing a molybdenum-based alloy, which is used to prepare the molybdenum-based alloy described above. The preparation method comprises:

[0020] A molybdenum matrix raw material and an alloying element raw material are mixed in proportion to obtain an alloy raw material, wherein the alloying element raw material includes at least one of a strengthening and toughening alloying element raw material and a purified alloying element raw material, the strengthening and toughening alloying element raw material includes at least one of a tantalum element raw material, an iridium element raw material, and a platinum element raw material; and the purified alloying element includes at least one of a strontium element raw material, a titanium element raw material, and a cerium element raw material;

[0021] Adding polydopamine to the alloy raw material, and processing the alloy raw material with the polydopamine added by an ingot melting method or a powder metallurgy method to obtain a primary molybdenum-based alloy product;

[0022] The molybdenum-based alloy primary product is subjected to a toughening treatment to obtain a molybdenum-based alloy substrate.

[0023] Optionally, the molybdenum matrix raw material, the toughening alloying element raw material, and the purified alloying element raw material are all in powder form;

[0024] The method of using powder metallurgy to process the alloy raw material added with polydopamine to obtain a molybdenum-based alloy primary product comprises:

[0025] uniformly mixing the alloy raw materials added with polydopamine to obtain mixed alloy powder;

[0026] Compressing the mixed alloy powder to obtain a mixed alloy compact;

[0027] The mixed alloy compact is sintered to obtain a molybdenum-based alloy primary product.

[0028] Optionally, before adding polydopamine to the alloy raw material, the preparation method further comprises:

[0029] The alloy raw material is annealed in a reducing atmosphere or under vacuum conditions.

[0030] Optionally, the polydopamine can be polymerized on the surface of the powder particles of the alloy raw material to form a polydopamine nanocoating with a thickness of 10 nanometers to 60 nanometers.

[0031] Optionally, the toughening treatment of the molybdenum-based alloy primary product to obtain a molybdenum-based alloy substrate comprises:

[0032] The molybdenum-based alloy primary product is subjected to solution treatment, thermal deformation treatment and annealing treatment in sequence to obtain a molybdenum-based alloy substrate.

[0033] In order to solve the above technical problems, the present invention further provides a medical implant device, wherein the material of the medical implant device is the molybdenum-based alloy described above.

[0034] To solve the above technical problems, the present invention further provides a method for preparing a medical implant device, comprising:

[0035] A molybdenum-based alloy substrate is prepared by the above-mentioned method for preparing the molybdenum-based alloy;

[0036] Performing a first processing step on the molybdenum-based alloy substrate to obtain a molybdenum-based alloy tube blank;

[0037] Performing a second processing step on the molybdenum-based alloy tube blank to obtain a preliminary finished medical implant device;

[0038] The medical implant device pre-finished product is post-processed to obtain a medical implant device finished product.

[0039] Optionally, performing a first processing step on the molybdenum-based alloy substrate to obtain a molybdenum-based alloy tube blank includes:

[0040] The molybdenum-based alloy substrate is subjected to hot perforation, hot extrusion or machining perforation to obtain a molybdenum-based alloy tube blank.

[0041] Optionally, the second processing step of the molybdenum-based alloy tube blank to obtain a preliminary finished medical implant device includes:

[0042] The molybdenum-based alloy tube blank is sequentially subjected to drawing, stress relief annealing and laser cutting to obtain a preliminary finished product of a medical implant device.

[0043] Optionally, the post-processing of the pre-finished medical implant device to obtain a finished medical implant device includes:

[0044] The medical implant device pre-finished product is sequentially subjected to pickling, heat treatment and polishing to obtain a medical implant device finished product.

[0045] Compared with the prior art, the molybdenum-based alloy, the preparation method of the molybdenum-based alloy, the medical implant device and the preparation method thereof provided by the present invention have the following beneficial effects:

[0046] The molybdenum-based alloy provided by the present invention comprises a molybdenum matrix, polydopamine, and alloying elements. The alloying elements include at least one of a strengthening and toughening alloying element and a purifying alloying element. The strengthening and toughening alloying element includes at least one of tantalum, iridium, and platinum; and the purifying alloying element includes at least one of strontium, titanium, and cerium. Thus, by adding polydopamine to the molybdenum-based alloy, sufficient adhesion and good cohesion are ensured on the surface of the alloy powder particles. It also provides good lubrication, thereby resolving the problems of insufficiently dense and uneven microstructures during the preparation of the molybdenum-based alloy. By adding tantalum, iridium, platinum and other strengthening alloying elements to the molybdenum-based alloy, the yield strength of the molybdenum-based alloy can be effectively reduced, thereby improving the plasticity of the molybdenum-based alloy, while also improving the recrystallization temperature and high-temperature performance of the molybdenum-based alloy. Moreover, tantalum, iridium, platinum and other strengthening alloying elements also improve the room-temperature performance, welding performance and radiation resistance of the molybdenum-based alloy. The addition of tantalum, iridium, platinum and other strengthening alloying elements can essentially solve the room-temperature brittleness and anisotropy problems of the molybdenum-based alloy, thereby improving the comprehensive performance of the molybdenum-based alloy and ensuring that the medical implants such as vascular stents made with the molybdenum-based alloy provided by the present invention have excellent mechanical properties under the in vivo use temperature conditions. By adding strontium, titanium, cerium and other purifying alloying elements to the molybdenum-based alloy, the content of interstitial impurities C, N and O can be reduced, thereby improving the brittleness and anisotropy problems of the molybdenum-based alloy, and strengthening the molybdenum matrix, thereby meeting the lateral elongation requirements required for the expansion of medical implants such as vascular stents during use. Furthermore, the molybdenum-based alloy provided by the present invention exhibits excellent corrosion resistance, degradation resistance, and development performance. Thus, the molybdenum-based alloy provided by the present invention can be used to prepare medical implants with high strength, toughness, and uniform performance, broadening the medical and clinical applications of molybdenum-based alloys.

[0047] Since the method for preparing the molybdenum-based alloy provided by the present invention can produce the molybdenum-based alloy provided by the present invention, the method for preparing the molybdenum-based alloy provided by the present invention has all the beneficial effects of the molybdenum-based alloy provided by the present invention. For details, please refer to the relevant description of the beneficial effects of the molybdenum-based alloy provided by the present invention above, which will not be repeated here. In addition, the method for preparing the molybdenum-based alloy provided by the present invention can further improve the mechanical properties of the final molybdenum-based alloy substrate by strengthening and toughening the molybdenum-based alloy pre-finished product, effectively ensuring that the final molybdenum-based alloy substrate has high strength and high toughness.

[0048] Since the material of the medical implant device provided by the present invention is the molybdenum-based alloy provided by the present invention, the medical implant device provided by the present invention not only has the advantages of high strength and toughness and uniform performance, but can also achieve uniform degradation, ensuring biological safety during use. At the same time, the medical implant device provided by the present invention also has excellent developability, which brings convenience to doctors' operation and clinical implementation.

[0049] Since the method for preparing the medical implant device provided by the present invention and the method for preparing the molybdenum-based alloy provided by the present invention belong to the same inventive concept, the method for preparing the medical implant device provided by the present invention has all the beneficial effects of the method for preparing the molybdenum-based alloy provided by the present invention. For details, reference may be made to the above description of the beneficial effects of the method for preparing the molybdenum-based alloy provided by the present invention, which will not be repeated here. BRIEF DESCRIPTION OF THE DRAWINGS

[0050] FIG1 is a schematic diagram showing a comparison of the corrosion resistance of a vascular stent made of a molybdenum-based alloy provided by the present invention and a vascular stent made of a cobalt-based alloy;

[0051] FIG2 a is a SEM surface morphology of a molybdenum-based alloy sheet provided by the present invention after uniform degradation;

[0052] FIG2 b is a SEM surface morphology of the molybdenum-based alloy wire provided by the present invention after uniform degradation;

[0053] FIG3 is a schematic flow chart of a method for preparing a molybdenum-based alloy according to one embodiment of the present invention;

[0054] FIG4 is a schematic flow chart of a method for preparing a medical implant device according to one embodiment of the present invention. DETAILED DESCRIPTION

[0055] The molybdenum-based alloy, method for preparing a molybdenum-based alloy, medical implant device, and method for preparing the same are further described in detail below in conjunction with the accompanying drawings and specific embodiments. The advantages and features of the present invention will become more apparent from the following description. It should be noted that the drawings are simplified and not to exact scale, and are intended only to facilitate and clearly illustrate the purpose of the embodiments of the present invention. To make the purposes, features, and advantages of the present invention more readily apparent, please refer to the accompanying drawings. It should be noted that the structures, proportions, and sizes illustrated in the drawings in this specification are intended solely to facilitate understanding and reading by those skilled in the art, and are not intended to limit the implementation of the present invention. Any structural modifications, changes in proportions, or adjustments to sizes, provided they produce the same or similar effects and achieve the same objectives, should still fall within the scope of the technical content disclosed herein. The specific design features of the present invention disclosed herein, including, for example, specific dimensions, directions, positions, and shapes, will be determined in part by the specific application and environment in which they are intended. Also, in the embodiments described below, sometimes the same reference numerals are used in common between different drawings to represent the same parts or parts having the same functions, and their repeated descriptions are omitted. In this specification, similar reference numerals and letters are used to represent similar items, so once an item is defined in one drawing, it does not need to be further discussed in subsequent drawings. In addition, if the method described herein includes a series of steps, the order of these steps presented herein is not necessarily the only order in which these steps can be performed, and some of the steps described may be omitted and / or some other steps not described herein may be added to the method.

[0056] It should be noted that, in this document, relational terms such as first and second, etc., are used solely to distinguish one entity or operation from another, and do not necessarily require or imply any actual relationship or order between these entities or operations, nor should they be understood to indicate or imply relative importance or implicitly specify the number of technical features indicated. Furthermore, the terms "comprise," "include," or any other variations thereof are intended to encompass non-exclusive inclusion, such that a process, method, article, or device comprising a series of elements includes not only those elements but also other elements not explicitly listed, or elements inherent to such process, method, article, or device. Without further limitation, an element defined by the phrase "comprising a..." does not preclude the presence of additional identical elements in the process, method, article, or device comprising the element. The singular forms "a," "an," and "the" include plural referents, the term "or" is generally used in a sense that includes "and / or," the term "several" is generally used in a sense that includes "at least one," and the term "at least two" is generally used in a sense that includes "two or more."

[0057] It should also be noted that, in the description of this specification, the reference terms "one embodiment", "some embodiments", "example", "specific example", or "some examples" and the like are intended to mean that the specific features, structures, materials or characteristics described in conjunction with the embodiment or example are included in at least one embodiment or example of the present invention. In this specification, the schematic representations of the above terms do not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described may be combined in an appropriate manner in any one or more embodiments or examples. In addition, those skilled in the art may combine and combine the different embodiments or examples described in this specification and the features of the different embodiments or examples, unless they are mutually inconsistent.

[0058] To facilitate understanding of the present invention, before specifically introducing the molybdenum-based alloy, the preparation method of the molybdenum-based alloy, the medical implant device and the preparation method thereof provided by the present invention, a brief introduction to the relevant properties of existing molybdenum and molybdenum-based alloys is first given.

[0059] The tensile strength of pure molybdenum is close to that of 316L, and its degradation rate is moderate, similar to that of Zn; its density is 10.2g / cm 3, with significantly better developability than cobalt-based and biodegradable materials (iron-, magnesium-, zinc-, and polymer-based). Furthermore, they are MRI-compatible. Compared to several existing biodegradable biomaterials, biodegradable molybdenum and molybdenum-based alloys offer significant advantages in mechanical properties, degradation resistance, biosafety, and X-ray visibility. They are currently the most ideal biodegradable stent materials and are expected to address key bottlenecks in the clinical application of the next generation of biodegradable metal vascular stents.

[0060] Molybdenum is a typical brittle refractory metal with a melting point of 2620°C, second only to tungsten, rhenium, and tantalum. Molybdenum and molybdenum-based alloys possess excellent high-temperature strength, good corrosion resistance, and unique mechanical and chemical properties. Under high-temperature conditions, they are high-temperature refractory metal materials that can meet stringent requirements and exhibit excellent overall performance. The toughness of molybdenum and molybdenum-based alloys changes with temperature, transitioning from ductile fracture to brittle fracture within a very narrow temperature range. The ductile-brittle transition temperature of pure molybdenum is approximately 140-150°C, making deep processing difficult, resulting in low product performance and limited application areas.

[0061] The core concept of the present invention is to provide a molybdenum-based alloy, a method for preparing a molybdenum-based alloy, a medical implant device and a method for preparing the same, in order to solve the problems that existing molybdenum and molybdenum-based alloys themselves have a series of processing characteristics such as high deformation temperature, severe oxidation at high temperature, high tensile strength, poor plasticity, rapid temperature drop, and a sharp increase in tensile strength with decreasing temperature, which make the deformation process of existing molybdenum and molybdenum-based alloys difficult. In particular, existing molybdenum and molybdenum-based alloys have two technical difficulties: low-temperature brittleness and relatively poor cross-sectional mechanical properties. These increase the difficulty of processing molybdenum-based alloy medical devices under conditions of use near room temperature, seriously limiting their development in the field of medical devices.

[0062] To achieve the above-mentioned objectives, the present invention provides a molybdenum-based alloy comprising a molybdenum matrix, polydopamine, and alloying elements. The alloying elements include at least one of a strengthening and toughening alloying element and a purifying alloying element. The strengthening and toughening alloying element includes at least one of tantalum, iridium, and platinum; and the purifying alloying element includes at least one of strontium, titanium, and cerium. Thus, by adding polydopamine to the molybdenum-based alloy, sufficient adhesion and good cohesion are ensured on the surface of the alloy powder particles. It also provides good lubrication, thereby resolving the problems of insufficiently dense and uneven microstructures during the preparation of molybdenum-based alloys. By adding tantalum, iridium, platinum and other strengthening alloying elements to the molybdenum-based alloy, the yield strength of the molybdenum-based alloy can be effectively reduced, thereby improving the plasticity of the molybdenum-based alloy, while also improving the recrystallization temperature and high-temperature performance of the molybdenum-based alloy. Moreover, tantalum, iridium, platinum and other strengthening alloying elements also improve the room-temperature performance, welding performance and radiation resistance of the molybdenum-based alloy. The addition of tantalum, iridium, platinum and other strengthening alloying elements can essentially solve the room-temperature brittleness and anisotropy problems of the molybdenum-based alloy, thereby improving the comprehensive performance of the molybdenum-based alloy and ensuring that the medical implants such as vascular stents made with the molybdenum-based alloy provided by the present invention have excellent mechanical properties under the in vivo use temperature conditions. By adding strontium, titanium, cerium and other purifying alloying elements to the molybdenum-based alloy, the content of interstitial impurities C, N and O can be reduced, thereby improving the brittleness and anisotropy problems of the molybdenum-based alloy, and strengthening the molybdenum matrix, thereby meeting the lateral elongation requirements required for the expansion of medical implants such as vascular stents during use. Furthermore, the molybdenum-based alloy provided by the present invention exhibits excellent corrosion resistance, degradation resistance, and development performance. Thus, the molybdenum-based alloy provided by the present invention can be used to prepare medical implants with high strength, toughness, and uniform performance, broadening the medical and clinical applications of molybdenum-based alloys.

[0063] The strengthening principle of the added strengthening and toughening alloy elements is introduced in detail below.

[0064] Specifically, only when the number of (s+d) electrons of the added element is greater than that of Mo (molybdenum) can the molybdenum-based alloy exhibit a significant softening effect. The (s+d) electron numbers of Ta (tantalum), Ir (iridium), and Pt (platinum) added in the present invention for strengthening and toughening the alloy are 43, 47, and 49, respectively, all of which are greater than the (s+d) electron number of Mo (molybdenum), which is 14. It is also worth noting that the number of s electrons of Ta (tantalum), Ir (iridium), and Pt (platinum) are all odd numbers. After being added to the molybdenum matrix, the problem of the directionality of the atomic bonding force caused by the asymmetric distribution of the sub-outer d electrons of pure molybdenum is improved. Furthermore, Ta (tantalum) and Ir (iridium) both have 2 electrons in their outermost shells, which are symmetrically distributed. Pt's outermost s electron shell has spherical symmetry, reflecting metallic bonding properties. Therefore, adding a toughening alloying element (at least one of Ta, Ir, or Pt) to a molybdenum matrix can significantly improve the tough-brittle properties of the molybdenum matrix, reduce the anisotropy of the molybdenum-based alloy, and significantly reduce the ductile-brittle transition temperature of the molybdenum-based alloy. This temperature decreases with increasing content of the toughening alloying element. When the toughening alloying element content reaches 50%, the ductile-brittle transition temperature can even drop to around -200°C. Furthermore, the addition of toughening alloying elements can increase the recrystallization temperature and high-temperature properties of molybdenum-based alloys, while also improving their room-temperature properties, weldability, and radiation resistance. The addition of toughening alloying elements can fundamentally address the room-temperature brittleness and anisotropy of molybdenum, thereby enhancing the overall performance of molybdenum-based alloys.

[0065] After adding a certain amount of strengthening alloying elements (at least one of Ta (tantalum), Ir (iridium), and Pt (platinum)) to molybdenum-based alloys, they have excellent room-temperature processing properties. The reasons can be summarized as follows: (1) Strengthening alloying elements can form MoXO4 type compounds with molybdenum, but unlike MoO2 type compounds, MoXO4 type compounds will not infiltrate grain boundaries; (2) Strengthening alloying elements can increase the solubility of C and O, making it difficult for carbides and oxides to precipitate, thereby preventing these impurity elements from segregating at grain boundaries; (3) Molybdenum-based alloys with added strengthening alloying elements undergo twinning deformation during low-temperature deformation, which is different from pure metallic molybdenum. Strengthening alloying elements change the electronic structure of molybdenum, reduce the directionality of atomic bonds, inhibit the transformation of molybdenum from metallic bonds to covalent bonds, reduce the stacking fault energy, and increase the shear modulus, thereby fundamentally solving the low-temperature brittle nature of Mo.

[0066] Furthermore, since Ta (tantalum), Ir (iridium), and Pt (platinum) all have relatively high densities, their addition can further enhance the developability of the molybdenum-based alloy provided by the present invention. It should be noted that, as those skilled in the art will appreciate, even without the addition of Ta (tantalum), Ir (iridium), and Pt (platinum), the developability of the molybdenum-based alloy itself is significantly superior to that of currently available biodegradable materials on the market.

[0067] In some exemplary embodiments, the mass percentage of the strengthening and toughening alloying element in the molybdenum-based alloy is less than or equal to 20%. This compositional arrangement ensures that the added strengthening and toughening alloying element can address the room-temperature brittleness and anisotropy issues of the molybdenum-based alloy, thereby improving the overall performance of the molybdenum-based alloy. It also effectively prevents excessive addition of the strengthening and toughening alloying element from affecting the degradability of the molybdenum-based alloy.

[0068] Furthermore, the mass percentage of the strengthening and toughening alloying element in the molybdenum-based alloy is less than or equal to 15%. Further, the mass percentage of the strengthening and toughening alloying element in the molybdenum-based alloy is less than or equal to 10%. Further, the mass percentage of the strengthening and toughening alloying element in the molybdenum-based alloy is less than or equal to 8%. Further, the mass percentage of the strengthening and toughening alloying element in the molybdenum-based alloy is less than or equal to 6%. Further, the mass percentage of the strengthening and toughening alloying element in the molybdenum-based alloy is less than or equal to 3%. Further, the mass percentage of the strengthening and toughening alloying element in the molybdenum-based alloy is 0.5% to 2%.

[0069] The strengthening principle of the added purified alloy elements is introduced in detail below.

[0070] Specifically, another important factor affecting the plastic and brittle properties of high-purity molybdenum is impurity elements. Furthermore, the interstitial impurities that affect the brittleness of molybdenum are mainly C, N, O, etc. Molybdenum metal is very sensitive to the segregation of these interstitial atoms at the grain boundaries. O easily forms oxides with other elements and segregates at the grain boundaries and within the grains, hindering grain boundary sliding and causing great damage to the plasticity of molybdenum. The presence of a small amount of N can greatly increase the risk of intergranular brittleness of molybdenum. An appropriate amount of C distributed at the grain boundaries can reduce the brittleness of molybdenum, but excessive C will form coarse carbide precipitation at the grain boundaries, significantly reducing the plasticity of molybdenum. In addition, the atomic ratio of C to O also affects the brittleness of molybdenum; when C / O is less than 2, the oxygen content is high and the plasticity of molybdenum deteriorates; when C / O exceeds 2, carbides precipitate, the molybdenum grain boundaries are strengthened, and the brittleness is reduced.

[0071] Generally speaking, the presence of nitrogen still increases the ductile-brittle transition temperature of polycrystalline molybdenum materials, increasing their brittleness. To address the accumulation of interstitial impurities at grain boundaries, the present invention incorporates purified alloying elements such as Sr (strontium), Ti (titanium), and Ce (cerium). These purified alloying elements react with the interstitial impurities C, N, and O to form fine, dispersed carbides with high melting points. These dispersed elements are then distributed within the matrix, providing dispersion strengthening, grain refinement, and dislocation retardation, significantly enhancing the room-temperature and high-temperature mechanical properties of the molybdenum matrix. On the one hand, the compounds formed by an appropriate amount of purified alloying elements (at least one of Sr (strontium), Ti (titanium), and Ce (cerium)) and interstitial impurities C, N, and O have a strong bonding force with the molybdenum matrix, and are mostly precipitated at the molybdenum grain boundaries, which can reduce the driving force for the segregation of C, N, and O atoms to the grain boundaries, thereby reducing the ductile-brittle transition temperature; on the other hand, the compounds formed by purified alloying elements such as Sr (strontium), Ti (titanium), and Ce (cerium) and interstitial impurities C, N, and O can effectively strengthen the interface with relatively weak bonding force of polycrystalline molybdenum, reduce the tendency of brittle fracture along the grain, improve anisotropy, and improve the plasticity of polycrystalline molybdenum-based alloys. In addition, during the preparation of molybdenum-based alloys, purified alloying elements such as Sr (strontium), Ti (titanium), and Ce (cerium) can wrap large particles of the main element (molybdenum or molybdenum + strengthening alloying elements) in the form of nanoparticles in the form of "hemp ball powder", which can effectively promote the formation of uniform equiaxed crystals as heterogeneous nucleation points, eliminating the cracking phenomenon caused by the growth of the original dendrite grains, and especially ensuring that the prepared medical implants (such as stents) meet the lateral elongation requirements required for post-expansion during the use of the product, laying a favorable foundation for obtaining high-strength and uniform-performance medical implants and broadening the medical clinical application range of molybdenum-based alloys.

[0072] In some exemplary embodiments, the mass percentage of the purified alloying element in the molybdenum-based alloy is less than or equal to 1.0%. This compositional arrangement not only ensures that the added purified alloying element can improve the brittleness and anisotropy of the molybdenum-based alloy and strengthen the molybdenum matrix, but also ensures that during the preparation of the molybdenum-based alloy, the purified alloying element can encapsulate large particles of the main element (molybdenum or molybdenum + strengthening alloying element) in the form of "hemp ball powder," acting as heterogeneous nucleation sites to effectively promote the formation of uniform equiaxed grains, eliminating cracking caused by the original dendritic grain growth.

[0073] Furthermore, the mass percentage of the purifying alloying element in the molybdenum-based alloy is less than or equal to 0.8%. Furthermore, the mass percentage of the purifying alloying element in the molybdenum-based alloy is less than or equal to 0.5%. Furthermore, the mass percentage of the purifying alloying element in the molybdenum-based alloy is less than or equal to 0.2%. Furthermore, the mass percentage of the purifying alloying element in the molybdenum-based alloy is less than or equal to 0.1%. Furthermore, the mass percentage of the purifying alloying element in the molybdenum-based alloy is less than or equal to 0.06%. Furthermore, the mass percentage of the purifying alloying element in the molybdenum-based alloy is between 0.01% and 0.04%.

[0074] The reinforcing mechanism of polydopamine is described in detail below.

[0075] Specifically, PDA (polydopamine) can use its own strong adhesion to wrap metal (including molybdenum matrix, toughening alloy elements, purified alloy elements) powder particles, thereby forming a uniform, dense, and more adhesive nano-coating, avoiding oxidation and impurities, improving the bonding strength of metal (including molybdenum matrix, toughening alloy elements, purified alloy elements) powder particles, and also acting as a lubricant during the powder forming process. In addition, the PDA (polydopamine) structure is a strong ligand for multivalent metal ions, such as strontium ions, titanium ions, and cerium ions, which can enhance the bonding force between powder particles and lay a good foundation for obtaining a high-density molybdenum-based alloy substrate with uniform structure.

[0076] Furthermore, the addition of PDA (polydopamine) to the forming agent in powder metallurgy can wet the metal powder and improve its compressibility. It also exhibits excellent dispersibility, evenly dispersing metal powder agglomerates one by one and breaking up particle agglomerates, thereby improving the uniformity of the structure and density. The mixture of metal powder and forming agent is often extruded to improve mixing and remove air, further enhancing the density of the powder metallurgy structure.

[0077] Since the amount of PDA (polydopamine) forming agent is preferably sufficient to coat the solid phase particles, and the coating is relatively thin at the nanometer level, the required amount is not large. In some exemplary embodiments, the mass percentage of PDA (polydopamine) in the molybdenum-based alloy is less than or equal to 1.5%. Further, the mass percentage of PDA (polydopamine) in the molybdenum-based alloy is less than or equal to 1.2%. Still further, the mass percentage of PDA (polydopamine) in the molybdenum-based alloy is less than or equal to 1%. Further, the mass percentage of PDA (polydopamine) in the molybdenum-based alloy is less than or equal to 0.7%. Further, the mass percentage of PDA (polydopamine) in the molybdenum-based alloy is less than or equal to 0.4%. Further, the mass percentage of PDA (polydopamine) in the molybdenum-based alloy is 0.1% to 0.3%.

[0078] In some exemplary embodiments, the mass percentage of impurity elements in the molybdenum-based alloy is less than or equal to 0.2%, and the impurity elements include at least one of chromium, copper, iron, nickel, tungsten, manganese, silicon, oxygen, nitrogen, carbon, and hydrogen. Specifically, the impurity elements are impurities that are inevitably introduced into the molybdenum-based alloy during its preparation, such as other metals (i.e., metals other than the molybdenum matrix, toughening alloying elements, and purifying alloying elements), semi-metals, metal salts, and / or non-metals. Because impurity elements can affect the plasticity and processing properties of the molybdenum-based alloy, the type and content of the impurity elements need to be strictly controlled.

[0079] Further, the mass percentage of the impurity element in the molybdenum-based alloy is less than or equal to 0.15, preferably, the mass percentage of the impurity element in the molybdenum-based alloy is less than or equal to 0.1%, even more preferably, the mass percentage of the impurity element in the molybdenum-based alloy is less than or equal to 0.08%, more preferably, the mass percentage of the impurity element in the molybdenum-based alloy is less than or equal to 0.06%, and most preferably, the mass percentage of the impurity element in the molybdenum-based alloy is less than or equal to 0.03%.

[0080] In some exemplary embodiments, the upper limit of the mass percentage of carbon in the molybdenum-based alloy (i.e., less than or equal to) is 0.03%, and the upper limit of the mass percentage of hydrogen, oxygen, and nitrogen in the molybdenum-based alloy (i.e., less than or equal to) is 0.02%. Furthermore, the mass percentage of all other impurity elements in the molybdenum-based alloy does not exceed (i.e., less than or equal to) 0.05%, more preferably, the mass percentage of all other impurity elements in the molybdenum-based alloy does not exceed (i.e., less than or equal to) 0.03%, and more preferably, the mass percentage of all other impurity elements in the molybdenum-based alloy is less than 0.01%, preferably less than 80 ppm (80 parts per million), more preferably less than 50 ppm (50 parts per million), and particularly preferably less than 20 ppm (20 parts per million).

[0081] Furthermore, Ca (calcium) and Mg (magnesium) are extremely detrimental to the plasticity of molybdenum-based alloys. The presence of these two elements in a molybdenum-based alloy can cause bubbling during the sintering process of the molybdenum billet and can also cause abnormally coarse recrystallized grains during recrystallization annealing, significantly detrimental to the plasticity of the molybdenum-based alloy. Furthermore, since Ca (calcium) and Mg (magnesium) are often distributed at grain boundaries, they themselves are also very detrimental to the plasticity of the molybdenum-based alloy. The presence of other elements, such as Fe (iron) and Ni (nickel), can reduce the high-temperature strength and recrystallization temperature of processed molybdenum-based alloys. Furthermore, crack sources often form at locations where Fe (iron) and Ni (nickel) are distributed during press working. Na (sodium) and Cu (copper) are immiscible with Mo (molybdenum). The presence of these two elements in the matrix can severely affect the processing properties of the molybdenum-based alloy. S (sulfur) is an extremely detrimental impurity element that can form sulfides with other impurities, forming eutectics in the matrix that are distributed along grain boundaries, causing the molybdenum-based alloy billet to exhibit hot brittleness. In addition, if the molybdenum-based alloy contains low-melting-point elements such as Pb, Bi, and Sn, the alloy will exhibit hot processing brittleness. Therefore, the raw materials of the molybdenum-based alloy provided by the present invention preferably do not contain any of the elements calcium (Ca), magnesium (Mg), iron (Fe), nickel (Ni), copper (Cu), sodium (Na), sulfur (S), lead (Pb), bismuth (Bi), and tin (Sn). Furthermore, the raw materials of the molybdenum-based alloy provided by the present invention also do not contain any of the elements zinc, rhenium, yttrium, and zirconium.

[0082] Please continue to refer to Table 1 and Table 2, wherein Table 1 shows the composition of the molybdenum-based alloys provided in Examples 1 to 8 of the present invention and the molybdenum and molybdenum-based alloys provided in Comparative Examples 1 to 5; Table 2 shows the performance test results of the molybdenum-based alloys provided in Examples 1 to 8 of the present invention and the molybdenum and molybdenum-based alloys provided in Comparative Examples 1 to 5.

[0083] Table 1 Molybdenum-based alloy composition

[0084] Table 2 Performance test results

[0085] Specifically, according to the alloy components listed in Table 1, the molybdenum-based alloys of Examples 1 to 8 and the molybdenum-based alloys of Comparative Examples 3 to 5 can be prepared by powder metallurgy or vacuum arc melting. Comparative Example 1 is commercial pure molybdenum (99.95%), and Comparative Example 2 is a commercial TZM alloy (molybdenum titanium zirconium alloy). Relevant performance tests, including elastic modulus, longitudinal yield strength, longitudinal tensile strength, longitudinal elongation, transverse tensile strength, transverse elongation, etc., are performed on them. In addition, corrosion resistance and degradation rate are tested to obtain the test results listed in Table 2. Since no obvious transverse tensile strength can be measured, this data is not listed in Table 2.

[0086] Existing research results indicate that pure molybdenum and TZM alloys (molybdenum-titanium-zirconium alloys) have a transverse elongation of zero. Tables 1 and 2 show that by adding toughening alloying elements (at least one of Ta, Ir, and Pt) and purifying alloying elements (at least one of Sr, Ti, and Ce), the molybdenum-based alloys provided in Examples 1 to 8 of the present invention exhibit significantly improved transverse and longitudinal mechanical properties (tensile strength and elongation) compared to commercial pure molybdenum and TZM alloys. Degradation immersion experiments revealed that TZM alloys are non-degradable.

[0087] As shown in Table 2, the molybdenum-based alloy provided in Comparative Example 3 contains 0.03% Ca. Due to the "bubbling" phenomenon of Ca distributed at the grain boundaries and the abnormally coarse recrystallized grains, the plasticity of the molybdenum-based alloy provided in Comparative Example 3 is very poor, with an axial elongation of only 2% and a radial elongation of 0. The molybdenum-based alloy provided in Comparative Example 4 contains 0.05% Fe, and its yield strength and tensile strength are also relatively low. Furthermore, since Fe forms crack sources during the press working process, it is also very detrimental to the plasticity of the molybdenum-based alloy, resulting in an axial elongation of only 5% and a radial elongation of 0 for the molybdenum-based alloy provided in Comparative Example 4. Therefore, molybdenum-based alloys cannot contain Ca and Fe. Because the mechanical properties (such as low elongation) of the Mo-Ca alloy provided in Comparative Example 3 and the Mo-Fe alloy provided in Comparative Example 4 are far from meeting the product use requirements of medical implant devices, degradation immersion tests and corrosion resistance tests were not performed on them.

[0088] By comparing Example 3 and Comparative Example 5, it is found that the alloy composition of Comparative Example 5 is consistent with the molybdenum-based alloy composition provided in Example 3 except that PDA (polydopamine) is not included. Since PDA is added to the molybdenum-based alloy provided in Example 3, the wettability and dispersibility of PDA can improve the density of the organization, reduce the residual pores inside the powder metallurgy sintered blank, and make the alloy density closer to the theoretical value. Therefore, the density of the molybdenum-based alloy provided in Example 3 is 11.51 g / cm 3 Higher than the density of the molybdenum-based alloy provided in Comparative Example 5, which is 10.02 g / cm 3 . In addition, the pores present in the alloy during post-processing and forming can become crack sources, reducing the mechanical properties of the alloy. Therefore, the addition of PDA also improves the mechanical properties. As can be seen from Table 2, the mechanical properties (strength and elongation) of the molybdenum-based alloy provided in Example 3 in different directions (longitudinal and transverse) are better than those of the molybdenum-based alloy provided in Comparative Example 5 without PDA.

[0089] Furthermore, since the densities of Ta, Ir, and Pt are 16.69 g / cm 3 , 22.56g / cm 3 , 21.45g / cm 3 Therefore, by adding at least one of Ta, Ir, and Pt to the molybdenum-based alloy, the density of the molybdenum-based alloy can be made higher than the density of the Mo matrix 10.28 g / cm 3 As shown in Table 2, the density of the molybdenum-based alloy provided by the present invention and added with at least one of Ta, Ir, and Pt is increased compared with the commercial pure molybdenum provided in Comparative Example 1 and the TZM alloy provided in Comparative Example 2. This indicates that the stent made of the molybdenum-based alloy provided by the present invention and added with at least one of Ta, Ir, and Pt has better developability.

[0090] Furthermore, the rebound of cardiovascular stents is mainly divided into radial rebound and axial retraction. Because the cardiovascular stent needs to be pressed onto the balloon, the axial retraction is greatly affected by the balloon and is difficult to uniformly evaluate, and the risk is not great. However, during use, the radial rebound of the cardiovascular stent is large, which is prone to the risk of stent displacement or poor wall adhesion. Therefore, the radial rebound of the cardiovascular stent needs to be evaluated in particular. It is generally stipulated that the radial retraction rate of the cardiovascular stent is less than 10%. Ideally, the lower the radial retraction rate of the cardiovascular stent, the better. The rebound resilience of the stent is mainly determined by the elastic modulus E of the alloy material. As can be seen from Table 2, the elastic modulus values ​​of the molybdenum-based alloys provided in Examples 1 to 8 of the present invention are lower than those of pure molybdenum. Therefore, the molybdenum-based alloys provided by the present invention can improve the rebound resilience of the stent.

[0091] Please continue to refer to Figure 1, which is a schematic diagram comparing the corrosion resistance of a vascular stent made using the molybdenum-based alloy provided by the present invention (specifically, the molybdenum-based alloy provided in Example 1) and a vascular stent made using a cobalt-based alloy. Specifically, according to the standard test method for corrosion sensitivity of small implantable devices by cyclic potentiodynamic polarization (ASTM F 2129-06) (YYT 0695-2008), the corrosion resistance of the vascular stent after post-expansion can be tested in the following manner: according to the standard medical device implantation process, the vascular stent is first pressed onto a balloon and then subjected to three simulated human body passages in a 37°C PBS (phosphate buffered saline) solution. The stent is then expanded to its nominal size using an inflator, and the pressure is continuously increased until the stent reaches its maximum post-expansion size. Based on this, the present invention further post-expanses the stent using a post-expansion balloon after expansion to its maximum post-expansion size until the stent struts are straightened. The actual post-expansion limit size of the vascular stent is approximately 25% greater than the specified limit size. The effectiveness of the present invention can be verified under this extreme condition.

[0092] Taking into account that vascular stents are Class III medical implants, they must have excellent corrosion resistance, requiring a breakdown potential ≥ 0.6V. Cobalt-based alloys are the mainstream stent medical alloys currently used on the market, and their corrosion resistance can meet the corrosion resistance requirements of the product, that is, their breakdown potential ≥ 0.6V. It is worth noting that when an obvious inflection point appears on the cyclic potentiodynamic polarization curve of the corrosion resistance test, it indicates that there is a breakdown potential, that is, pitting corrosion has occurred. Although the corrosion resistance of the vascular stents made of cobalt-based alloys and the vascular stents made of molybdenum-based alloys provided by the present invention both meet the specified breakdown potential requirements, it can be seen from Figure 1 that the cyclic potentiodynamic polarization curve of the vascular stent made of cobalt-based alloys has an obvious inflection point at about 0.65V, indicating that a breakdown phenomenon has occurred, that is, pitting corrosion has occurred in the cobalt-based alloy. However, the vascular stent made of the molybdenum-based alloy provided by the present invention does not show an inflection point on the curve until the voltage increases to 1V, indicating that the breakdown potential of the vascular stent made of the molybdenum-based alloy provided by the present invention is greater than 1V. This also shows that the molybdenum-based alloy has excellent corrosion resistance and can meet the product usage requirements of three types of medical implant devices.

[0093] Please continue to refer to Figures 2a and 2b, where Figure 2a is a SEM (scanning electron microscope) surface morphology image of the molybdenum-based alloy sheet provided by the present invention after uniform degradation, and Figure 2b is a SEM (scanning electron microscope) surface morphology image of the molybdenum-based alloy wire provided by the present invention after uniform degradation. Specifically, the molybdenum-based alloy sheet provided in Example 3 and the molybdenum-based alloy wire provided in Example 5 were polished and cleaned, and then placed on a shaker at a speed of 100 rpm (Revolutions Per Minute). The surface morphology after immersion in PBS (phosphate buffered saline) at 37° C. for one month is shown in Figures 2a and 2b. As can be seen from Figures 2a and 2b, the molybdenum-based alloy provided by the present invention can achieve uniform degradation, whether it is a large sheet or a stent-scale wire. Through uniform exfoliation and stable degradation layer by layer, the degraded sheets and wires with a nanometer thickness are about 10 μm in an equiaxed shape; the degradation products include Mo, O, Ca, Mn, Na and P elements, which are soluble in human body simulated fluid; and no obvious large-particle degradation product or precipitate enrichment occurs during the degradation process, ensuring biological safety during use.

[0094] To achieve the above-mentioned concept, the present invention further provides a method for preparing a molybdenum-based alloy, which is used to prepare the molybdenum-based alloy described above. Please refer to FIG3 , which is a schematic flow diagram of a method for preparing a molybdenum-based alloy provided in one embodiment of the present invention. As shown in FIG3 , the method for preparing a molybdenum-based alloy provided by the present invention comprises the following steps:

[0095] Step S110: Mixing a molybdenum matrix raw material and an alloying element raw material in proportion to obtain an alloy raw material, wherein the alloying element raw material includes at least one of a strengthening and toughening alloying element raw material and a purification alloying element raw material, the strengthening and toughening alloying element raw material includes at least one of a tantalum element raw material, an iridium element raw material, and a platinum element raw material; the purified alloying element includes at least one of a strontium element raw material, a titanium element raw material, and a cerium element raw material.

[0096] Step S120: adding polydopamine to the alloy raw material, and processing the alloy raw material with the polydopamine added by an ingot melting method or a powder metallurgy method to obtain a primary molybdenum-based alloy product.

[0097] Step S130: performing a toughening treatment on the molybdenum-based alloy primary product to obtain a molybdenum-based alloy substrate.

[0098] Since the method for preparing the molybdenum-based alloy provided by the present invention can produce the molybdenum-based alloy provided by the present invention, the method for preparing the molybdenum-based alloy provided by the present invention has all the beneficial effects of the molybdenum-based alloy provided by the present invention. For details, please refer to the relevant description of the beneficial effects of the molybdenum-based alloy provided by the present invention above, which will not be repeated here. In addition, the method for preparing the molybdenum-based alloy provided by the present invention can further improve the mechanical properties of the final molybdenum-based alloy substrate by strengthening and toughening the molybdenum-based alloy pre-finished product, effectively ensuring that the final molybdenum-based alloy substrate has high strength and high toughness.

[0099] Specifically, the molybdenum matrix raw material, the toughening alloying element raw material, and the purified alloying element raw material are all 99.95% pure. Ingot melting is primarily accomplished through arc melting and electron beam melting. Further details regarding arc melting and electron beam melting are known to those skilled in the art and will not be further elaborated here.

[0100] In some exemplary embodiments, the molybdenum matrix raw material, the strengthening and toughening alloying element raw material, and the purified alloying element raw material are all in powder form. It should be noted that, as will be understood by those skilled in the art, when a molybdenum-based alloy is prepared by an ingot melting method, the molybdenum matrix raw material, the strengthening and toughening alloying element raw material, and the purified alloying element raw material can be in powder form or in bulk form. However, when a molybdenum-based alloy is prepared by a powder metallurgy method, the molybdenum matrix raw material, the strengthening and toughening alloying element raw material, and the purified alloying element raw material are preferably in powder form.

[0101] In some exemplary embodiments, before adding polydopamine to the alloy raw material, the preparation method further comprises:

[0102] The alloy raw material is annealed in a reducing atmosphere or under vacuum conditions.

[0103] Therefore, by annealing in a reducing atmosphere or vacuum conditions, the oxides can be reduced, impurities can be removed, and the purity of the powder can be improved; in addition, annealing can also eliminate the work hardening of the powder, improve the plasticity during the powder pressing process, and stabilize the crystal structure of the powder.

[0104] Specifically, dopamine can be added to the annealed alloy raw material as a forming agent (forming agents may also include traditional binders and lubricants). When dopamine comes into contact with air under weakly alkaline conditions, it can polymerize on the surface of the powder particles and form polydopamine (PDA). The PDA forming agent in a viscous flow state has both certain adhesive properties and lubricity. PDA acts as a shell that evenly wraps around the surface of each alloy element powder, forming a stable nano-scale coating, effectively preventing the presence of impurities such as oxide layers on the surface of the raw material particles. At the same time, it also acts as a lubricant during the continuous compression molding process, avoiding quality defects such as delamination, scratches, and fuzz, reducing friction between the compact and the mold, and ensuring smooth operation of the mold.

[0105] PDA uses its superior adhesion to coat alloying element powder particles, thereby forming a uniform, dense, and more adhesive polydopamine nanocoating. This prevents oxidation and impurities, improves the bonding strength of the metal powder particles, and also acts as a lubricant during the powder forming process. In some exemplary embodiments, the thickness of the polydopamine nanocoating is 10 to 60 nanometers. Furthermore, the thickness of the polydopamine nanocoating is 10 to 50 nanometers. Still further, the thickness of the polydopamine nanocoating is 10 to 40 nanometers. Still further, the thickness of the polydopamine nanocoating is 10 to 30 nanometers. Still further, the thickness of the polydopamine nanocoating is 10 to 20 nanometers.

[0106] In some exemplary embodiments, the powder metallurgy method is used to process the alloy raw material to which polydopamine is added to obtain a molybdenum-based alloy primary product, including:

[0107] uniformly mixing the alloy raw materials added with polydopamine to obtain mixed alloy powder;

[0108] Compressing the mixed alloy powder to obtain a mixed alloy compact;

[0109] The mixed alloy compact is sintered to obtain a molybdenum-based alloy primary product.

[0110] Specifically, the alloy raw material added with polydopamine can be mixed uniformly by mechanical or chemical methods on a mixer such as a ball mill or a V-type mixer, so that the mixed alloy powder composed of coarse particles and fine particles with an appropriate particle size distribution has a high tap density, which is beneficial to reduce the porosity and promote the rearrangement, recrystallization and grain growth of the powder during the sintering process.

[0111] By subjecting loose mixed alloy powder to a certain pressing pressure within a die, the powder particles move and rearrange as a whole, forming cold welds between adjacent particle surfaces, resulting in a mixed alloy compact with a specific size, shape, density, and strength. As the forming pressure increases, the porosity of the mixed alloy compact decreases. The addition of polydopamine to the forming agent ensures sufficient adhesion and good cohesion on the surface of the alloy powder particles, enhancing the bonding force between the powder particles and facilitating maximum densification of the mixed alloy compact. Polydopamine also exhibits excellent dispersion properties and ensures a uniform density distribution in the mixed alloy compact.

[0112] Furthermore, the mixed alloy compact can be sintered in a reducing atmosphere or under vacuum conditions by solid phase sintering or liquid phase sintering. Through solid phase sintering or liquid phase sintering, atoms migrate by thermal activation, so that the powder particles form metallurgical bonds and grain boundaries; each alloying element forms new compounds at the matrix grain boundaries through dissolution reaction, alloying reaction and solid state diffusion. Sintering mainly goes through three stages: formation of bonding surface, formation and growth of sintering neck, and formation and spheroidization of closed pores. Preferably, when a small amount of low melting point alloying elements (such as strontium, titanium, and cerium) are added to the molybdenum-based alloy, the mixed alloy compact can be sintered by liquid phase sintering. The low melting point alloying elements such as strontium, titanium, and cerium can be used as activation sintering additives to provide a liquid phase, and the refractory component (molybdenum matrix) always remains in a solid phase. Under the action of capillary force, the liquid phase flows and fills the pore space; the sharp corners of the powder particles preferentially dissolve in the liquid phase, making it easy to obtain effective particle filling; at the same time, the surface of the solid phase particles is smoothed and spheroidized, reducing the resistance to particle rearrangement, and a fully dense, high-elongation powder metallurgy molybdenum-based alloy material can be produced.

[0113] In some exemplary embodiments, the toughening treatment of the molybdenum-based alloy pre-finished product to obtain a molybdenum-based alloy substrate comprises:

[0114] The molybdenum-based alloy primary product is subjected to solution treatment, thermal deformation treatment and annealing treatment in sequence to obtain a molybdenum-based alloy substrate.

[0115] Therefore, by sequentially performing solution treatment, thermal deformation treatment and annealing treatment on the molybdenum-based alloy primary product, the mechanical properties of the molybdenum-based alloy can be further improved, effectively ensuring that the prepared molybdenum-based alloy substrate has the advantages of high strength and high toughness.

[0116] Specifically, the molybdenum-based alloy pre-finished product can be subjected to solution treatment in sequence by solid-solid doping, solid-liquid doping, liquid-liquid doping and other methods, wherein the liquid-liquid doping process can achieve the maximum uniform mixing between ions, and ultimately realize a significant improvement in the structural uniformity and mechanical properties of the molybdenum-based alloy substrate. Furthermore, the molybdenum-based alloy pre-finished product after solution treatment can be subjected to thermal deformation treatment by hot forming processes such as rolling, extrusion or forging. By performing annealing treatment after the thermal deformation treatment, the stress generated during the thermal deformation process can be eliminated, and the anisotropy of the molybdenum-based alloy substrate finally obtained can be improved. It should be noted that, as can be understood by those skilled in the art, an annealing process can be interspersed during the thermal deformation process to effectively eliminate the stress generated during the thermal deformation process and ensure that the thermal deformation treatment process can proceed smoothly.

[0117] To achieve the above-mentioned objectives, the present invention further provides a medical implant device, wherein the material of the hospital implant device is the molybdenum-based alloy described above. Because the medical implant device provided by the present invention is made of the molybdenum-based alloy provided by the present invention, the medical implant device provided by the present invention not only has the advantages of high strength and toughness and uniform performance, but also can achieve uniform degradation, ensuring biosafety during use. Furthermore, the medical implant device provided by the present invention has excellent developability, which brings convenience to doctors' operation and clinical implementation.

[0118] Specifically, the medical implant device provided by the present invention can be a medical stent implanted in a human cavity, including vascular stents and non-vascular stents, wherein vascular stents include but are not limited to coronary stents, peripheral stents, covered stents, intracranial stents, venous stents, left atrial appendage occluder stents, vascular filters, atrial / ventricular septal occluders, and embolic protectors; non-vascular stents include but are not limited to esophageal stents, biliary stents, and nasal stents.

[0119] Furthermore, the surface of the medical implant device (e.g., a vascular stent) provided by the present invention can be smooth or rough, grooved or ungrooved, perforated or unperforated, or can include, but not be limited to, any other grooves or micropores suitable for drug delivery. Specifically, the molybdenum-based alloy substrate prepared above can be processed into a tubular member, which can then be cut to form a rod, and grooves or micropores can be drilled into the rod for drug delivery.

[0120] In some other embodiments, a drug active layer can also be directly coated on the surface of a medical implant device (e.g., a vascular stent). Furthermore, the drugs in the drug active layer include drugs for treating cardiovascular and cerebrovascular diseases, drugs for treating tumor diseases, drugs for treating intestinal diseases, drugs for treating urinary tract diseases, etc. Furthermore, the drugs include but are not limited to at least one of paclitaxel, docetaxel, copper aspirinate, tacrolimus, hydroxycamptothecin, vinblastine, doxorubicin, rapamycin, and rapamycin derivatives.

[0121] In some exemplary embodiments, the present invention further provides a method for preparing a medical implant device. Please refer to FIG4 , which is a schematic flow chart of a method for preparing a medical implant device according to one embodiment of the present invention. As shown in FIG4 , the method for preparing a medical implant device provided by the present invention includes the following steps:

[0122] Step S210: Prepare a molybdenum-based alloy substrate using the above-mentioned method for preparing the molybdenum-based alloy.

[0123] Step S220: performing a first processing step on the molybdenum-based alloy substrate to obtain a molybdenum-based alloy tube blank.

[0124] Step S230: performing a second processing step on the molybdenum-based alloy tube blank to obtain a preliminary finished medical implant device.

[0125] Step S240: post-processing the preliminary finished medical implant device to obtain a finished medical implant device.

[0126] Since the method for preparing the medical implant device provided by the present invention and the method for preparing the molybdenum-based alloy provided by the present invention belong to the same inventive concept, the method for preparing the medical implant device provided by the present invention has all the beneficial effects of the method for preparing the molybdenum-based alloy provided by the present invention. For details, reference may be made to the above description of the beneficial effects of the method for preparing the molybdenum-based alloy provided by the present invention, which will not be repeated here.

[0127] In some exemplary embodiments, the first processing step of the molybdenum-based alloy substrate to obtain a molybdenum-based alloy tube blank includes:

[0128] The molybdenum-based alloy substrate is subjected to hot perforation, hot extrusion or machining perforation to obtain a molybdenum-based alloy tube blank.

[0129] In some exemplary embodiments, the second processing step of the molybdenum-based alloy tube blank to obtain a preliminary finished medical implant device includes:

[0130] The molybdenum-based alloy tube blank is sequentially subjected to drawing, stress relief annealing and laser cutting to obtain a preliminary finished product of a medical implant device.

[0131] Therefore, stress relief annealing after drawing can effectively eliminate the processing stress generated during the drawing process, thereby improving the anisotropy of the medical implant device and enhancing the plasticity of the medical implant device.

[0132] In some exemplary embodiments, the post-processing of the pre-finished medical implant device to obtain a finished medical implant device includes:

[0133] The medical implant device pre-finished product is sequentially subjected to pickling, heat treatment and polishing to obtain a medical implant device finished product.

[0134] Specifically, pickling can remove cutting debris, heat-affected layers, and contaminants from the surface of pre-finished medical implants. Heat treatment can remove processing stresses during the processing of pre-finished medical implants, improve the anisotropy of the medical implants, and enhance the plasticity of the medical implants. Polishing (e.g., electrochemical polishing) can remove the oxide layer on the surface of pre-finished medical implants, resulting in a bright, smooth surface and reducing the surface roughness of the finished medical implants. This, in turn, reduces the risk of thrombosis and tissue reactions after implantation, allowing the dimensions of the medical implants to meet design requirements.

[0135] In summary, compared with the prior art, the molybdenum-based alloy, the preparation method of the molybdenum-based alloy, the medical implant device and the preparation method thereof provided by the present invention have the following beneficial effects:

[0136] (1) By adding polydopamine to the molybdenum-based alloy, it can ensure that the surface of the alloy powder particles has sufficient adhesion and good adhesion, and at the same time it can also play a good lubricating role, thereby solving the problem of insufficient density and uneven organization in the preparation process of the molybdenum-based alloy.

[0137] (2) By adding strengthening alloying elements such as tantalum, iridium, and platinum to the molybdenum-based alloy, the yield strength of the molybdenum-based alloy can be effectively reduced, thereby improving the plasticity of the molybdenum-based alloy. At the same time, the recrystallization temperature and high-temperature performance of the molybdenum-based alloy can also be improved. In addition, the strengthening alloying elements such as tantalum, iridium, and platinum also have an improving effect on the room-temperature performance, welding performance, and radiation resistance of the molybdenum-based alloy. The addition of strengthening alloying elements such as tantalum, iridium, and platinum can essentially solve the room-temperature brittleness and anisotropy problems of the molybdenum-based alloy, making its brittle-to-ductile transition temperature far lower than room temperature, and no room-temperature brittleness occurs, ensuring that the medical implant devices such as vascular stents made of the molybdenum-based alloy provided by the present invention have excellent mechanical properties under the temperature conditions of in vivo use.

[0138] (3) By adding purified alloying elements such as strontium, titanium, and cerium to the molybdenum-based alloy, the content of interstitial impurities C, N, and O can be reduced, thereby improving the brittleness and anisotropy of the molybdenum-based alloy and strengthening the molybdenum matrix, thereby meeting the lateral elongation requirements required for the expansion of medical implants such as vascular stents during use.

[0139] (4) The molybdenum-based alloy provided by the present invention has uniform degradation performance, good solubility of degradation products, and no obvious enrichment of large-particle degradation products, which effectively improves the biological safety during use.

[0140] (5) The molybdenum-based alloy provided by the present invention also has excellent developing properties, which solves the current problem of developing properties of degradable metals or polymers, and brings great convenience to doctors' operation and clinical implementation.

[0141] It should be noted that the above description is merely a description of preferred embodiments of the present invention and does not limit the scope of the present invention. Any changes or modifications made by persons skilled in the art based on the above disclosure are within the scope of protection of the present invention. Obviously, those skilled in the art may make various changes and modifications to the invention without departing from the spirit and scope of the present invention. Thus, if such modifications and variations fall within the scope of the present invention and its equivalents, the present invention is intended to include such modifications and variations.

Claims

1. A molybdenum-based alloy, characterized in that: It includes a molybdenum matrix, polydopamine and alloy elements, wherein the alloy elements include at least one of a strengthening alloy element and a purifying alloy element, wherein the strengthening alloy element includes at least one of tantalum, iridium and platinum; and the purifying alloy element includes at least one of strontium, titanium and cerium.

2. The molybdenum-based alloy according to claim 1, characterized in that The mass percentage of the toughening alloying element in the molybdenum-based alloy is less than or equal to 20%.

3. The molybdenum-based alloy according to claim 2, characterized in that The mass percentage of the strengthening and toughening alloy element in the molybdenum-based alloy is 0.5% to 2%.

4. The molybdenum-based alloy according to claim 1, characterized in that The mass percentage of the purifying alloying element in the molybdenum-based alloy is less than or equal to 1.0%.

5. The molybdenum-based alloy according to claim 4, characterized in that The mass percentage of the purified alloy element in the molybdenum-based alloy is 0.01% to 0.04%.

6. The molybdenum-based alloy according to claim 1, characterized in that The mass percentage of the polydopamine in the molybdenum-based alloy is less than or equal to 1.5%.

7. The molybdenum-based alloy according to claim 6, characterized in that The mass percentage of the polydopamine in the molybdenum-based alloy is 0.1% to 0.3%.

8. The molybdenum-based alloy according to claim 1, characterized in that The mass percentage of impurity elements in the molybdenum-based alloy is less than or equal to 0.2%, and the impurity elements include at least one of chromium, copper, iron, nickel, tungsten, manganese, silicon, oxygen, nitrogen, carbon and hydrogen.

9. The molybdenum-based alloy according to claim 8, characterized in that The mass percentages of copper, iron and nickel in the molybdenum-based alloy are all less than 20 ppm; the mass percentage of carbon in the molybdenum-based alloy is less than or equal to 0.03%, the mass percentages of hydrogen, oxygen and nitrogen in the molybdenum-based alloy are all less than or equal to 0.02%; the mass percentages of chromium, silicon, tungsten and manganese in the molybdenum-based alloy are all less than or equal to 0.05%.

10. The molybdenum-based alloy according to claim 1, characterized in that The molybdenum-based alloy does not contain any of calcium, magnesium, sodium, sulfur, lead, bismuth, zinc, rhenium, yttrium, zirconium and tin.

11. A method for preparing a molybdenum-based alloy, for preparing the molybdenum-based alloy according to any one of claims 1 to 10, characterized in that: The preparation method comprises: The molybdenum matrix raw material and the alloy element raw material are mixed in proportion to obtain the alloy raw material, wherein the alloy element raw material includes at least one of a toughened alloy element raw material and a purified alloy element raw material, the toughened alloy element raw material includes at least one of a tantalum element raw material, an iridium element raw material and a platinum element raw material; the purified alloy element includes at least one of a strontium element raw material, a titanium element raw material and a cerium element raw material; Adding polydopamine to the alloy raw material, and treating the alloy raw material with polydopamine added by an ingot smelting method or a powder metallurgy method to obtain a molybdenum-based alloy primary product; The molybdenum-based alloy primary product is subjected to a toughening treatment to obtain a molybdenum-based alloy substrate.

12. The method for preparing a molybdenum-based alloy according to claim 11, characterized in that: The molybdenum matrix raw material, the toughening alloy element raw material, and the purified alloy element raw material are all in powder form; The method of using powder metallurgy to process the alloy raw material added with polydopamine to obtain a molybdenum-based alloy primary product comprises: Mixing the alloy raw materials added with polydopamine uniformly to obtain mixed alloy powder; Compressing the mixed alloy powder to obtain a mixed alloy compact; The mixed alloy compact is sintered to obtain a molybdenum-based alloy primary product.

13. The method for preparing a molybdenum-based alloy according to claim 8, characterized in that: The polydopamine can be polymerized on the surface of the powder particles of the alloy raw material to form a polydopamine nano coating with a thickness of 10 nanometers to 60 nanometers.

14. A medical implant device, characterized in that: The material of the medical implant device is the molybdenum-based alloy according to any one of claims 1 to 10.

15. A method for preparing a medical implant device, characterized in that: The preparation method comprises: A molybdenum-based alloy substrate is prepared by the method for preparing a molybdenum-based alloy according to any one of claims 11 to 13; Performing a first processing step on the molybdenum-based alloy substrate to obtain a molybdenum-based alloy tube blank; Performing a second processing step on the molybdenum-based alloy tube blank to obtain a preliminary finished product of a medical implant device; The preliminary finished product of the medical implant device is post-processed to obtain a finished medical implant device.

Images