A degradable ZnZrCu alloy with amorphous-crystal heterostructure and a preparation method thereof

Abstract

The application relates to a degradable ZnZrCu alloy with an amorphous-crystal heterostructure and a preparation method thereof, and belongs to the field of material design and preparation. The application proposes a combined process route of mechanical alloying and selective laser melting to in-situ synthesize a ductile phase in an amorphous matrix, and develops a degradable ZnZrCu alloy with both amorphous phase and ductile phase. The medical Zn-based amorphous alloy developed by the application shows good strength-plasticity synergy and good degradation rate. The application inherits the advantages of additive manufacturing of selective laser melting, can effectively break through the size limitation of traditional forming process of amorphous alloy, realize the individual customization of the shape and structure of the amorphous alloy, and provides a new idea for the preparation of the amorphous-crystal heterostructure alloy and biomedical application. Meanwhile, the application is simple in composition, controllable in process, and convenient for large-scale industrial application.

Description

Technical Field

[0001] This invention relates to a biodegradable ZnZrCu alloy with an amorphous-crystalline heterostructure and its preparation method; it belongs to the field of materials design and preparation. Background Technology

[0002] Zn-based alloys and composites, as potential biodegradable materials, possess a suitable degradation rate, and their degradation products can be bioabsorbed. However, as implants, the poor mechanical properties of pure Zn metal cannot match those of human bone. In recent years, amorphous structures have emerged as a promising strategy to address the insufficient strength of pure Zn as an implant. In particular, studies have found that ZnZr amorphous alloys exhibit high strength. Moreover, Zn is an indispensable element in the body, closely related to many biological functions; Zr also possesses good biocompatibility and bone integration capabilities. However, similar to other amorphous materials, ZnZr amorphous alloys exhibit low plastic strain (<2%) due to shear band softening effects.

[0003] Based on the aforementioned problems and requirements, the preparation of biodegradable ZnZr amorphous alloys with mechanical properties matching human bone tissue and good biocompatibility has promising application prospects. This invention employs mechanical alloying and selective laser melting techniques, and adds Cu, which has good ductility and biocompatibility, as an alloying element to synthesize a tough phase in situ within an amorphous matrix, thus preparing a biodegradable ZnZrCu alloy with an amorphous-crystalline heterostructure. Summary of the Invention

[0004] To address the shortcomings of existing technologies, this invention proposes for the first time a process route combining mechanical alloying and selective laser melting to prepare ZnZrCu alloys with amorphous-crystalline heterostructures possessing excellent mechanical properties. Firstly, mechanical alloying forces ZnZrCu to transform from a crystalline to an amorphous state, while simultaneously synthesizing a tough phase (ε-CuZn5 phase) in situ within the amorphous structure, thus preparing ZnZrCu alloy powder containing amorphous-crystalline heterostructures. Subsequently, optimized selective laser melting parameters are used to maintain the amorphous structure, thereby obtaining a ZnZrCu alloy with an amorphous-crystalline heterostructure.

[0005] This invention discloses a biodegradable ZnZrCu alloy with an amorphous-crystalline heterostructure, wherein the Cu content is 0-15 wt.%, preferably 8-10 wt.%, and the mass ratio of Zn to Zr is 40-60:60-40, preferably 60:40.

[0006] Within this range, the prepared alloy has the advantages of both amorphous and crystalline phases. The disordered atomic structure of the amorphous phase can endow the alloy with excellent mechanical strength, while the tough phase can hinder the rapid propagation of shear bands and promote the initiation and dispersion of multiple shear bands, thus achieving the purpose of toughening the alloy.

[0007] In the biodegradable ZnZrCu alloy with an amorphous-crystalline heterostructure, the amorphous structure accounts for 60% to 85% of the mass, preferably 65% ​​to 83%.

[0008] The present invention discloses a biodegradable ZnZrCu alloy with an amorphous-crystalline heterostructure, wherein the biodegradable ZnZrCu alloy with an amorphous-crystalline heterostructure contains ε-CuZn5.

[0009] This invention discloses a biodegradable ZnZrCu alloy with an amorphous-crystalline heterostructure. The amorphous ZnZrCu alloy powder is prepared by mechanical alloying, and then a ZnZrCu alloy with both amorphous-crystalline heterostructure is prepared by selective laser melting.

[0010] This invention relates to a biodegradable ZnZrCu alloy with an amorphous-crystalline heterostructure. The raw materials used for mechanical alloying are pure Zn, pure Zr, and pure Cu powders. The average particle size of the pure Zn powder is 55–65 μm, preferably 60 μm; the average particle size of the pure Zr powder is 70–80 μm, preferably 75 μm; and the average particle size of the pure Cu powder is 0.5–3 μm, preferably 1–2 μm. The purity of all the powders is higher than 99.99%.

[0011] The present invention relates to a method for preparing a biodegradable ZnZrCu alloy with an amorphous-crystalline heterostructure, comprising the following steps: (1) mixing Zn powder and Zr powder in a mass ratio of 40-60:60-40, preferably 60:40, using hard 304 stainless steel grinding balls with diameters of 5-7 mm and 8-10 mm, loading ZnZrCu powder and 304 stainless steel grinding balls into a stainless steel ball milling jar in a ball-material (grinding ball and powder) mass ratio of 10:1 to 20:1, using anhydrous ethanol as the grinding medium, and filling with argon gas for protection after vacuuming.

[0012] (2) ZnZu powder is subjected to high-energy ball milling at a ball milling speed of 320-390 r / min, preferably 320-375 r / min, and a ball milling time of 10-30 h, preferably 15-25 h, to obtain ZnZr alloy powder.

[0013] (3) Cu powder is added to ZnZr mixed powder according to the set composition, and high-energy ball milling is performed to obtain ZnZrCu alloy powder; the amount of Cu powder added is 3 to 15 wt.% of the mass of ZnZrCu alloy powder, preferably 8 to 10 wt.%;

[0014] (4) Using the obtained ZnZrCu alloy powder as raw material, ZnZrCu alloy was prepared by selective laser melting under argon protection. The forming parameters were: laser power 70-100W, scanning speed 80-120mm / s, laser spot diameter 50-100μm, scanning spacing 40-80μm, and layer thickness 80-120μm.

[0015] This invention relates to a method for preparing a biodegradable ZnZrCu alloy with an amorphous-crystalline heterostructure. The raw materials used for mechanical alloying are pure Zn, pure Zr, and pure Cu powders. The average particle size of the pure Zn powder is 55–65 μm, preferably 60 μm; the average particle size of the pure Zr powder is 70–80 μm, preferably 75 μm; and the average particle size of the pure Cu powder is 0.5–3 μm, preferably 1–2 μm. The purity of all the powders is higher than 99.99%.

[0016] This invention relates to a method for preparing a biodegradable ZnZrCu alloy with an amorphous-crystalline heterostructure: in step (1), the mass ratio of the ball to the material is 10:1 to 20:1, preferably 10:1 to 15:1, and more preferably 15:1; the mass ratio of the 6mm and 10mm stainless steel balls is preferably 1 to 3:1, preferably 2:1.

[0017] As a preferred embodiment, the present invention relates to a biodegradable ZnZrCu alloy with an amorphous-crystalline heterostructure and its preparation method, wherein the ball milling speed in step (2) is 320-350 r / min.

[0018] As a preferred embodiment, the present invention relates to a biodegradable ZnZrCu alloy with an amorphous-crystalline heterostructure and its preparation method, wherein the ball milling time in step (2) is 10-30 h, and more preferably 20 h.

[0019] As a preferred embodiment, the present invention relates to a biodegradable ZnZrCu alloy with an amorphous-crystalline heterostructure and a method for preparing the same, wherein the Cu content in step (3) is 3-15 wt.%, more preferably 8-10 wt.%.

[0020] Preferably, this invention relates to a method for preparing a biodegradable ZnZrCu alloy with an amorphous-crystalline heterostructure. In step (3), stainless steel grinding balls with diameters of 6 mm and 10 mm (mass ratio of 1 to 3:1, preferably 2:1) are used. The ball-to-material mass ratio is controlled at 12 to 20:1, preferably 15:1. The grinding speed is 320 to 350 r / min, and the grinding time is 15 to 28 h, preferably 20 to 24 h, to obtain amorphous ZnZrCu alloy powder. This invention uses two different sizes of grinding balls and a higher ball-to-material mass ratio combined with appropriate grinding speed and time to obtain highly amorphous ZnZrCu alloy powder. This provides the necessary conditions for subsequent 3D printing to prepare high-quality products with an amorphous-crystalline heterostructure.

[0021] As a preferred embodiment, this invention relates to a method for preparing a biodegradable ZnZrCu alloy with an amorphous-crystalline heterostructure. In step (4), the process parameters are further preferably: laser power of 80–100 W, scanning speed of 80–110 mm / s, laser spot diameter of 50 μm, scanning spacing of 80 μm, and layer thickness of 0.1 mm. In this invention, too low a printing power will result in the powder not melting properly, easily leading to the formation of the ε-CuZn5 phase. Furthermore, the resulting product will have excessive defects and pores, resulting in extremely poor material mechanical properties. Too high a printing power will lead to a reduction or complete disappearance of the amorphous phase, while the ε-CuZn5 phase will also coarsen, resulting in a monocrystalline ZnZrCu alloy. As a further preferred embodiment, this invention relates to a method for preparing a biodegradable ZnZrCu alloy with an amorphous-crystalline heterostructure. In step (4), the process parameters are further preferably: laser power of 80 W, scanning speed of 110 mm / s, laser spot diameter of 50 μm, scanning spacing of 80 μm, and layer thickness of 100 μm.

[0022] This invention relates to a biodegradable ZnZrCu alloy with an amorphous-crystalline heterostructure and its preparation method. After optimization, the resulting alloy has a compressive yield strength of 160–195 MPa and an elongation of 1.5–4.2%.

[0023] Principles and advantages

[0024] This invention is the first to utilize mechanical alloying and selective laser melting to prepare a biodegradable ZnZrCu alloy with both amorphous and crystalline heterostructures. Mechanical alloying is essentially a high-energy ball milling process, where two or more metal-to-metal or metal-to-nonmetal mixtures are placed in a high-energy ball mill with a specific ratio of grinding balls to obtain fine-grained, uniformly composed alloyed powder. Specifically, as a non-equilibrium powder solid-state alloying technology, mechanical alloying, through prolonged and intense impacts and collisions between powder particles and grinding balls / jars, causes repeated deformation, cold welding, and fracture of the powder particles. This improves the chemical activity of the components, lowers the diffusion energy barrier, and enables the powder to be alloyed at the atomic level and continuously refined. Unlike ordinary solid-state reactions, the thermodynamics and kinetics of mechanical alloying make it possible to prepare alloy systems that are difficult to produce using traditional smelting processes, as well as quasi-steady-state and non-equilibrium alloys far from thermodynamic equilibrium. Furthermore, during mechanical alloying, the morphology, grain size, and solid solution degree of the multi-component mixed powder exhibit certain regularities as the ball milling time increases. The time and degree of complete alloying of the mixed powder are highly sensitive to the ball milling parameters.

[0025] This invention is based on the mechanism of Cu doping expanding the mixing enthalpy and atomic size mismatch of the Zn-Zr alloy system. It utilizes mechanical alloying to break through the traditional amorphous composition range, forcibly causing the periodic arrangement of ZnZrCu crystal atoms to become unstable, thereby inducing a transformation from crystalline to amorphous state. Simultaneously, rapid atomic diffusion promotes the in-situ synthesis of the tough phase (ε-CuZn5), thus obtaining a ZnZrCu alloy powder with a coexistence of amorphous and crystalline phases (preferably ZnZrCu alloy powder with a Cu addition of 8-10 wt.%). On the other hand, the amorphous ZnZrCu powder prepared by mechanical alloying has a long-range disordered atomic structure in a thermodynamically metastable state. If it cannot melt and solidify at an extremely high rate during subsequent alloy forming, the metastable amorphous atoms will crystallize through long-range diffusion, thus losing their original amorphous structure. Therefore, the selective laser melting process used in this invention has a small laser action area (micrometer level), a short laser time (millisecond level), and an extremely high molten pool cooling rate, which can effectively suppress crystallization during the forming process, thereby maintaining the amorphous structure constructed in mechanical alloying and preparing an amorphous-crystalline heterostructure ZnZrCu alloy; during the selective laser melting process, an appropriate laser-material interaction mechanism is also conducive to the uniform distribution of the ductile phase in the amorphous matrix.

[0026] The mechanical alloying process parameters of this invention directly determine the crystalline to amorphous transformation of ZnZrCu powder during alloying, as well as the in-situ synthesis of the ductile phase. If the energy input during ball milling is too low, the powder may only be broken down and simply mixed, failing to form an amorphous structure, and the ductile phase will not be synthesized in situ. If the energy input during ball milling is too high, the already refined powder particles may agglomerate due to the increased surface free energy, reducing the system's energy and causing significant coarsening of the powder, failing to meet the powder quality requirements of selective laser melting. Therefore, only when the ball milling parameters are within the range of this invention can the amorphous transformation of ZnZrCu powder be achieved, while still meeting the requirements of the selective laser melting process in terms of powder shape and particle size.

[0027] The amount of Cu added in this invention directly affects the transformation from crystalline to amorphous state, and also determines the mechanical properties, degradation rate, and biocompatibility of the ZnZrCu alloy. If the Cu content is too low, not only is the amorphous phase insufficient to meet strength requirements, but the ductile phase content is also low, resulting in minimal improvement in plasticity. Conversely, if the Cu content is too high, the alloy degrades too quickly, and excessive Cu release can pose certain health risks. Therefore, only when the Cu content is within the range specified in this invention can a good synergistic effect between the amorphous and ductile phases be achieved, thus meeting the performance requirements of the implant.

[0028] The selective laser melting process parameters of this invention affect the maintenance of the amorphous structure during the ZnZrCu powder forming process. For example, when the laser energy density is too low, the amorphous powder cannot be completely melted, resulting in problems such as particle inclusions and low density, leading to poor mechanical properties or even failure to form the prepared ZnZrCu alloy. When the laser energy density is too high, due to Zn's lowest melting and boiling points and high vapor pressure, oxidation burn-off and dust splashing are easily caused, affecting the forming quality of the ZnZrCu alloy. More importantly, the reduced solidification rate of the molten pool exacerbates the recrystallization of the amorphous phase, even causing coarsening and disappearance of the tough phase. Therefore, only when the selective laser melting process parameters are within the range of this invention can the amorphous and tough phases formed by mechanical alloying be preserved to the greatest extent, thereby preparing an amorphous-crystalline heterostructure ZnZrCu alloy with excellent mechanical properties.

[0029] The amorphous-crystalline heterostructure ZnZrCu alloy prepared in this invention exhibits excellent comprehensive mechanical properties and a suitable degradation rate due to the synergistic effect of the amorphous and ductile phases. On the one hand, amorphous alloys, due to their disordered atomic arrangement and lack of typical crystal defects such as dislocations and grain boundaries found in crystalline alloys, possess excellent strength but lack good plasticity; that is, the amorphous structure lacks a good dissipation mechanism for applied stress. It is well known that during deformation at room temperature, almost all stress and strain are highly concentrated within shear bands only a few tens of nanometers thick. Due to the localized temperature rise and shear expansion effect near the shear bands, the shear bands rapidly soften and propagate into cracks, causing rapid fracture of the amorphous alloy. Therefore, the characteristics of shear bands play a crucial role in the strength and plasticity of amorphous alloys. Studies have found that the generation and interaction of multiple shear bands, such as network-type and superimposed multiple shear bands, can dissipate energy and disperse stress, thereby generating a certain degree of plastic deformation in the system. This invention introduces a ductile phase into the ZnZrCu amorphous alloy to construct a heterogeneous region between amorphous and crystalline phases. Specifically, the amorphous structure, acting as the hard phase, enhances the material's strength, while the ductile phase, acting as the soft phase, effectively promotes the multiplication of shear bands and delays or even inhibits crack formation. Furthermore, due to the differences in hardness and modulus within the heterogeneous regions, stress during plastic deformation often concentrates at the interface between the amorphous matrix and the ductile phase, further promoting shear band formation. Moreover, the interaction of shear bands in the multi-slip system leads to a more uniform stress distribution, preventing localized material failure. On the other hand, the amorphous-crystalline heterostructure ZnZrCu alloy prepared in this invention, due to the galvanic corrosion formed by the addition of Cu in the heterogeneous region, accelerates the alloy's degradation rate, enabling it to participate in human metabolism and tissue regeneration, thus offering significant advantages as a medical implant.

[0030] The main advantages of this invention are:

[0031] (1) This invention utilizes the non-equilibrium and forced characteristics of mechanical alloying to break through the traditional amorphous composition range and realize the transformation of ZnZrCu from crystalline to amorphous state under solid conditions, so as to prepare highly amorphous ZnZrCu alloy powder.

[0032] (2) The condition parameters for selective laser melting controlled by the present invention can effectively suppress rapid crystallization during the amorphous forming process, thereby providing the necessary conditions for preparing ZnZrCu alloys with amorphous-crystalline heterostructure.

[0033] (3) This invention utilizes the additive manufacturing characteristics of selective laser melting to solve the alloy size limitations of traditional amorphous preparation processes, and can also realize personalized customization of the shape and structure of amorphous alloys.

[0034] (4) The addition of Cu in this invention further improves the amorphization ability during mechanical alloying. At the same time, the tough phase (ε-CuZn5) synthesized in situ can promote the multiplication of shear bands, prevent the expansion of cracks, and enhance mechanical properties.

[0035] (5) The amorphous-crystalline heterostructure ZnZrCu alloy prepared by the present invention can also be gradually degraded in the human body environment, and the degradation products have good biocompatibility and biological functions, and can participate in human metabolism and tissue regeneration, which has significant advantages as a medical implant. Attached Figure Description

[0036] Appendix Figure 1 X-ray diffraction patterns of ZnZrCu powder obtained by mechanical alloying in Examples 1-4;

[0037] Appendix Figure 2 The images show transmission electron microscope (TEM) images of the amorphous-crystalline ZnZrCu powder obtained in Example 2 and the amorphous-crystalline alloy formed by selective laser melting. (a) is a TEM image of the amorphous powder; (b) is a scanning electron microscope (SEM) image of the microstructure of the ε-CuZn5 ductile phase distribution in the ZnZrCu alloy prepared by selective laser melting. Detailed Implementation

[0038] The specific implementation of the present invention will be described below through examples:

[0039] Example 1

[0040] Zn powder (60 μm particle size, 99.99% purity) and Zr powder (75 μm particle size, 99.99% purity) were mixed at a mass ratio of 60:40. Hardened 304 stainless steel grinding balls with diameters of 6 mm and 10 mm were used. The Zn powder, Zr powder, and 304 stainless steel grinding balls were loaded into a stainless steel ball milling jar at a ball-to-powder (ball and powder) mass ratio of 15:1. Anhydrous ethanol was used as the grinding medium, and the jar was evacuated and then filled with argon gas for protection. The Zn and Zr powders were ball-milled at a speed of 350 r / min for 20 h to obtain ZnZr alloy powder.

[0041] After obtaining ZnZr alloy powder, 3 wt.% Cu powder (particle size 1-2 μm, purity 99.99%) was added at a mass ratio of Cu:(Zn+Zr+Cu) = 3% and mixed with the ZnZr alloy powder. The ZnZr-Cu mixed powder and grinding balls were loaded into a stainless steel ball mill jar at a ball-to-powder mass ratio of 15:1. Anhydrous ethanol was added as the grinding medium, and the jar was evacuated and then filled with high-purity argon for protection. Hard steel balls with diameters of 6 mm and 10 mm (mass ratio Φ6 mm grinding ball: Φ10 mm grinding ball = 2:1) were used at a milling speed of 350 r / min for 20 hours to obtain ZnZrCu alloy powder. Using the ball-milled ZnZrCu alloy powder as raw material, ZnZrCu alloy was prepared by selective laser melting under a protective atmosphere. The laser power was controlled at 80W, the scanning speed at 110mm / s, the laser spot diameter at 50μm, the scanning spacing at 80μm, and the layer thickness at 0.1mm.

[0042] Tests revealed that when the Cu content was 3 wt.%, most of the mechanically alloyed ZnZrCu powder transformed into an amorphous state, and an ε-CuZn5 tough phase was synthesized in situ (see attached image). Figure 1 The subsequent selective laser melting technique preserved the original amorphous structure and ε-CuZn5 phase, constructing a heterogeneous region composed of amorphous and crystalline phases (of which the amorphous structure accounts for 65.41% by mass). The alloy has a compressive yield strength of 160.9 MPa and a tensile strength of 1.6%.

[0043] Example 2

[0044] Zn powder (60 μm particle size, 99.99% purity) and Zr powder (75 μm particle size, 99.99% purity) were mixed at a mass ratio of 60:40. Hardened 304 stainless steel grinding balls with diameters of 6 mm and 10 mm were used. The Zn powder, Zr powder, and 304 stainless steel grinding balls were loaded into a stainless steel ball milling jar at a ball-to-powder (ball and powder) mass ratio of 15:1. Anhydrous ethanol was used as the grinding medium, and the jar was evacuated and then filled with argon gas for protection. The Zn and Zr powders were ball-milled at a speed of 350 r / min for 20 h to obtain ZnZr alloy powder.

[0045] After obtaining ZnZr alloy powder, 5 wt.% Cu powder (particle size 1-2 μm, purity 99.99%) was added at a mass ratio of Cu:(Zn+Zr+Cu) = 5% and mixed with the ZnZr alloy powder. The ZnZr-Cu mixed powder and grinding balls were loaded into a stainless steel ball mill jar at a ball-to-powder mass ratio of 15:1. Anhydrous ethanol was added as the grinding medium, and the jar was evacuated and then filled with high-purity argon for protection. Hard steel balls with diameters of 6 mm and 10 mm (mass ratio: Φ6 mm grinding ball: Φ10 mm grinding ball = 2:1) were used at a milling speed of 350 r / min for 20 hours to obtain ZnZrCu alloy powder. Using the ball-milled ZnZrCu alloy powder as raw material, ZnZrCu alloy was prepared by selective laser melting under a protective atmosphere. The laser power was controlled at 80W, the scanning speed at 110mm / s, the laser spot diameter at 50μm, the scanning spacing at 80μm, and the layer thickness at 0.1mm.

[0046] Tests revealed that when the Cu content was 5 wt.%, most of the mechanically alloyed ZnZrCu powder transformed into an amorphous state, and an ε-CuZn5 tough phase was synthesized in situ (see attached image). Figure 1 and Figure 2 The subsequent selective laser melting technique preserved the original amorphous structure and ε-CuZn5 phase, constructing a heterogeneous region composed of amorphous and crystalline phases (of which the amorphous structure accounts for 81.71% by mass). The alloy has a compressive yield strength of 181.5 MPa and a tensile strength of 3.4%.

[0047] Example 3

[0048] Zn powder (60 μm particle size, 99.99% purity) and Zr powder (75 μm particle size, 99.99% purity) were mixed at a mass ratio of 60:40. Hardened 304 stainless steel grinding balls with diameters of 6 mm and 10 mm were used. The Zn powder, Zr powder, and 304 stainless steel grinding balls were loaded into a stainless steel ball milling jar at a ball-to-powder (ball and powder) mass ratio of 15:1. Anhydrous ethanol was used as the grinding medium, and the jar was evacuated and then filled with argon gas for protection. The Zn and Zr powders were ball-milled at a speed of 350 r / min for 20 h to obtain ZnZr alloy powder.

[0049] After obtaining ZnZr alloy powder, 5 wt.% Cu powder (particle size 1-2, purity 99.99%) was added at a mass ratio of Cu:(Zn+Zr+Cu) = 10% and mixed with the ZnZr alloy powder. The ZnZr-Cu mixed powder and grinding balls were loaded into a stainless steel ball mill jar at a ball-to-powder mass ratio of 15:1. Anhydrous ethanol was added as the grinding medium, and the jar was evacuated and then filled with high-purity argon for protection. Hard steel balls with diameters of 6 mm and 10 mm (mass ratio: Φ6 mm grinding ball: Φ10 mm grinding ball = 2:1) were used at a milling speed of 350 r / min for 20 hours to obtain ZnZrCu alloy powder. Using the ball-milled ZnZrCu alloy powder as raw material, ZnZrCu alloy was prepared by selective laser melting under a protective atmosphere. The laser power was controlled at 80W, the scanning speed at 110mm / s, the laser spot diameter at 50μm, the scanning spacing at 80μm, and the layer thickness at 0.1mm.

[0050] Tests revealed that when the Cu content was 15 wt.%, most of the mechanically alloyed ZnZrCu powder transformed into an amorphous state, and an ε-CuZn5 toughening phase was synthesized in situ (see attached image). Figure 1 The subsequent selective laser melting technique preserved the original amorphous structure and ε-CuZn5 phase, constructing a heterogeneous region composed of amorphous and crystalline phases (of which the amorphous structure accounts for 82.78% by mass). The alloy has a compressive yield strength of 189.4 MPa and a tensile strength of 4.1%.

[0051] Example 4

[0052] The other conditions were the same as in Example 2, except that: the ZnZrCu mixed powder and grinding balls were loaded into a stainless steel ball mill jar at a ball-to-powder mass ratio of 15:1, anhydrous ethanol was added as the grinding medium, and after evacuation, high-purity argon gas was introduced for protection. Hard steel balls with diameters of 6 mm and 10 mm (mass ratio: 6 mm grinding ball: 8 mm grinding ball = 2:1) were used, the ball milling speed was 50 r / min, and the ball milling time was 6 hours to obtain ZnZrCu powder.

[0053] Tests revealed that when the Cu content was 5 wt.%, the ZnZrCu powder after simple physical mixing did not undergo a phase structure transformation.

[0054] Comparative Example 1

[0055] Other parameters are the same as in Example 1, except that: after obtaining ZnZr alloy powder, when ball milling the ZnZrCu mixed powder, the ball mill speed is 400 r / min.

[0056] Tests revealed that the powder after ball milling was severely welded, with most of the powder welded to the tank wall or wrapped around the grinding balls. Only a small amount of powder could be obtained, and the powder was severely coarsened. The powder shape and particle size could not meet the requirements of the subsequent selective laser melting process.

[0057] Comparative Example 2

[0058] Other parameters are the same as in Example 1, except that: after obtaining ZnZr alloy powder, the ball-to-material mass ratio is 10:1 when the ZnZr-Cu mixed powder is ball-milled.

[0059] Tests revealed that the powder did not show obvious bonding after ball milling, but the relatively low ball-to-powder ratio could not provide enough energy to induce the high amorphization of the alloy powder. Therefore, only a small amount of amorphous phase was formed in the powder, and the ZnZrCu alloy after selective laser melting was composed entirely of a single crystalline structure.

[0060] Comparative Example 3

[0061] Other parameters are the same as in Example 2, except that: after obtaining ZnZr alloy powder, the ball mill speed is 200 r / min when ball milling ZnZr-Cu mixed powder.

[0062] Tests revealed that no alloying reaction occurred in the powder after ball milling, therefore no amorphous phase was formed in the powder, and the ZnZrCu alloy after selective laser melting was composed entirely of a single crystalline structure.

[0063] Comparative Example 4

[0064] Other parameters are the same as in Example 2, except that: after obtaining ZnZr alloy powder, the ball milling time of ZnZr-Cu mixed powder is 5h.

[0065] Tests revealed that the powder did not undergo an alloying reaction after ball milling; it was merely a simple physical mixing process. Therefore, no amorphous phase was formed in the powder, and the ZnZrCu alloy after selective laser melting consisted entirely of a single crystalline structure.

[0066] Comparative Example 5

[0067] Other parameters are the same as in Example 3, except that the laser power is controlled at 150W and the scanning speed is 50mm / s.

[0068] Tests revealed that the ball-milled ZnZrCu powder had essentially transformed into an amorphous state, but the alloy underwent a crystalline transformation during selective laser melting, and the ε-CuZn5 phase was significantly coarsened. The prepared ZnZrCu alloy was basically composed of a single crystalline structure.

[0069] Comparative Example 6

[0070] Other parameters are the same as in Example 3, except that the laser power is controlled at 60W and the scanning speed is 150mm / s.

[0071] Tests revealed that after mechanical alloying, the ZnZrCu powder had essentially transformed into an amorphous state. However, due to insufficient energy density in the selected area laser melting process, a significant amount of powder failed to melt completely, and the ε-CuZn5 phase exhibited agglomeration. Furthermore, the prepared ZnZrCu alloy had poor forming quality, with numerous defects and voids within the alloy, which deteriorated its mechanical properties.

[0072] Comparative Example 7

[0073] The other conditions were the same as in Example 3, except that the ball milling time was 30 hours and the rotation speed was 500 r / min to obtain ZnZrCu powder.

[0074] Tests revealed that the ZnZrCu powder after high-energy ball milling exhibited significant welding, forming a blocky mixture, which is not conducive to selective laser melting and forming.

[0075] Comparative Example 8 was conducted under the same conditions as Example 4, except that the ball milling time was 10 hours and the rotation speed was 300 r / min, resulting in ZnZrCu powder.

[0076] X-ray diffraction results of the powder showed that the ZnZrCu powder after high-energy ball milling underwent a slight alloying reaction and there was basically no amorphous phase. Combined with energy dispersive spectroscopy, it was found that the weak alloying reaction only occurred on the surface of the powder particles, and no reaction occurred inside the particles.

Claims

1. A biodegradable ZnZrCu alloy with an amorphous-crystalline heterostructure, characterized in that: The alloy It contains Zn, Zr, and Cu, and the total content of Zn, Zr, and Cu is greater than or equal to 98%; The alloy contains both ε-CuZn5 phase and amorphous phase; The alloy is prepared by the following steps: (1) Mix Zn powder and Zr powder in a mass ratio of 40~60:60~40. Use hard 304 stainless steel grinding balls with diameters of 5~7 mm and 8~10 mm. Load ZnZrCu powder and 304 stainless steel grinding balls into a stainless steel ball milling jar in a ball-material mass ratio of 10:1~20:

1. Use anhydrous ethanol as the grinding medium. After vacuuming, fill with argon gas for protection. (2) ZnZr powder was subjected to high-energy ball milling at a ball milling speed of 320~390 r / min and a ball milling time of 10~30 h to obtain ZnZr alloy powder; (3) Add Cu powder to the ZnZr mixed powder according to the set composition, and perform high-energy ball milling to obtain ZnZrCu alloy powder; the amount of Cu powder added is 3~15wt.% of the mass of ZnZrCu alloy powder. (4) Using the obtained ZnZrCu alloy powder as raw material, ZnZrCu alloy was prepared by selective laser melting under argon protection. The forming parameters were: laser power 70~100 W, scanning speed 80~120 mm / s, laser spot diameter 50~100 μm, scanning spacing 40~80 μm, and layer thickness 80~120 μm. In step (3), stainless steel grinding balls with diameters of 6 mm and 10 mm are used at a mass ratio of 1~3:1, the ball material mass ratio is controlled at 12~20:1, the ball milling speed is 320~350 r / min, and the ball milling time is 15~28h to obtain amorphous ZnZrCu alloy powder.

2. The biodegradable ZnZrCu alloy with an amorphous-crystalline heterostructure according to claim 1, characterized in that: In the alloy, the mass ratio of amorphous structure is 60% to 85%.

3. The biodegradable ZnZrCu alloy with an amorphous-crystalline heterostructure according to claim 1, characterized in that: In the alloy, the mass ratio of amorphous structure is 65-83%.

4. The biodegradable ZnZrCu alloy with an amorphous-crystalline heterostructure according to claim 1, characterized in that: In step (1), Zn powder and Zr powder are mixed in a mass ratio of 60:40; In step (2), the rotation speed is 320~375 r / min and the ball milling time is 15~25h.

5. The biodegradable ZnZrCu alloy with an amorphous-crystalline heterostructure according to claim 1, characterized in that: The raw materials used for mechanical alloying are pure Zn, pure Zr and pure Cu powders; the average particle size of pure Zn powder is 55~65 μm, the average particle size of pure Zr powder is 70~80 μm, and the average particle size of pure Cu powder is 0.5~3 μm, and the purity of the powders is higher than 99.99%.

6. The biodegradable ZnZrCu alloy with an amorphous-crystalline heterostructure according to claim 1, characterized in that: In step (1), the ball-to-material mass ratio is 15:1; stainless steel balls with diameters of 6mm and 10mm are used, with a mass ratio of 1 to 3:

1.

7. The biodegradable ZnZrCu alloy with an amorphous-crystalline heterostructure according to claim 3, characterized in that: In step (3), the amount of Cu powder added is 8~10 wt.%.

8. The biodegradable ZnZrCu alloy with an amorphous-crystalline heterostructure according to claim 3, characterized in that: In step (4), the laser power is 80~100 W, the scanning speed is 80~110 mm / s, the laser spot diameter is 50 μm, the scanning spacing is 80 μm, and the layer thickness is 0.1 mm.

9. A biodegradable ZnZrCu alloy with an amorphous-crystalline heterostructure according to any one of claims 3-8, characterized in that: The resulting alloy has a compressive yield strength of 160~195 MPa and an elongation of 1.5~4.2%.

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