Magnesium alloy composite material with micro-battery system and preparation method

Abstract

The application relates to a magnesium alloy composite material with a micro-battery system, which comprises a Mg matrix with a weight content of more than 50%, and further comprises light rare earth elements or intermetallic compounds formed by the light rare earth elements and molten magnesium, the light rare earth elements or the intermetallic compounds formed by the light rare earth elements and molten magnesium have an electrochemical potential difference with the Mg matrix and form a micro-battery system, and more than 50% of the light rare earth-rich cathode phase is distributed around the periphery of the alpha-Mg matrix phase grain.

Description

Technical Field

[0001] This application relates to a magnesium alloy composite material with a micro battery system and its preparation method. Background Technology

[0002] Existing soluble magnesium alloys rely on the formation of discretely distributed precipitates from heavy metal elements such as Cu, Ni, and Co as the cathode phase, but they have the following problems:

[0003] (1) The distribution of precipitate phase is random and uneven, which may lead to local preferential corrosion and the formation of honeycomb residue;

[0004] (2) Heavy metals such as Cu and Ni are harmful to the environment and human body;

[0005] (3) The heavy metal solubilization system has a mechanism defect of unstable dissolution behavior.

[0006] Existing Mg-Mn-RE systems aim for high thermal conductivity, but Mn cannot construct high potential difference microcouple systems and instead inhibits corrosion and dissolution. For example, CN117026036B discloses a high thermal conductivity, high strength wrought magnesium alloy and its preparation method, which adds light rare earth elements such as La and Ce to the Mg-Mn alloy system. Mn has very low solid solubility in magnesium alloys and does not react with Mg, so its effect on improving the mechanical properties of as-cast alloys is limited. However, during hot deformation, elemental manganese particles dynamically precipitate, inhibiting dislocation movement, thereby refining the magnesium alloy grains and improving the mechanical properties of the wrought alloy. When the Mn content is around 2%wt, its effect on the thermal conductivity of magnesium alloys is still relatively small. Light rare earth elements have low solid solubility in magnesium, so their effect on reducing the thermal conductivity of magnesium alloys is minimal, and they also have the functions of purifying the melt, refining the alloy microstructure, and improving the room temperature and high temperature mechanical properties of the alloy. In this patent, the alloying element Mn is in a supersaturated state within the cast magnesium matrix, while the light rare earth elements exist as Mg-RE phases and solute atoms. During extrusion hot deformation, the Mg-RE phase effectively pins grain boundaries, provides heterogeneous nucleation sites, and promotes dynamic recrystallization, refining the grains of the extruded alloy. During hot extrusion, the phase is broken down into fine particles, thus the light rare earth elements play a role in grain refinement and second-phase strengthening, resulting in high alloy strength. Furthermore, due to the low solid solubility of Mn and light rare earth elements, a large amount of nanoscale second phase dynamically precipitates during extrusion, hindering grain boundary movement and inhibiting the growth of recrystallized grains. While strengthening the alloy, the large amount of dynamically precipitated nanoscale phases also significantly reduces the solute atoms in the magnesium matrix by consuming them, greatly reducing the lattice distortion of the magnesium matrix and significantly weakening the scattering of electrons and phonons during heat conduction, thereby improving the alloy's thermal conductivity.

[0007] The prior application 202610679250.5 filed by the applicant is the basic patent for the improvements made in this application, and the patent proposes several directions for technical improvement. Summary of the Invention

[0008] The purpose of this application is to provide a magnesium alloy composite material with a micro-battery system and its preparation method, which uses an intermetallic compound formed by light rare earth elements and magnesium as the cathode phase of the micro-battery, and is particularly suitable for the manufacture of downhole soluble tools for unconventional oil and gas extraction such as shale oil and gas.

[0009] This application relates to a magnesium alloy composite material with a micro-battery system, comprising Mg with a weight content of more than 50%, and further comprising light rare earth elements or intermetallic compounds formed by light rare earth elements and molten magnesium, wherein the weight content of the light rare earth elements or intermetallic compounds formed by light rare earth elements and molten magnesium is between 0.05% and 10% based on the rare earth element content; the light rare earth elements or intermetallic compounds formed by light rare earth elements and molten magnesium have an electrochemical potential difference with the Mg matrix to form a micro-battery system, and more than 50% of the light rare earth-rich cathode phase is distributed around the α-Mg matrix phase. This allows the establishment of conductive channels that can be activated by water molecules between the matrix phases, enabling the rare earth cathode phase and the magnesium matrix phase to form an electrochemical dissolution reaction circuit.

[0010] In this process, at least 5% of the light rare earth elements or the intermetallic compounds formed by the light rare earth elements and molten magnesium are coated or adsorbed in the porous inert material. During the melting and cooling process, the precipitates are distributed around the α-Mg matrix phase grains of the magnesium alloy composite material, forming preferential channels for Mg atoms to lose electrons and transport outwards; or, the light rare earth elements and molten magnesium form eutectic, hypoeutectic, twin, or peritectic structures during the solidification process, so that the precipitated phase and the magnesium matrix form a partially coherent or completely incoherent interface relationship.

[0011] The specific surface area of ​​the porous inert material is between 200 and 1000 m². 2 Between / g. The porous inert material is added by enriching the additive containing light rare earth elements in the capillary of the porous inert material in the form of adsorption, coating or semi-coating, and then adding the porous inert material enriched with additives into the melt, stirring, dispersing, and condensing to crystallize so that the light rare earth additives exist in the vicinity of the matrix phase in at least one form of metal, intermetallic compound, salt or ion.

[0012] This also includes pre-added components that serve as non-spontaneous nucleation centers. These pre-added components are uniformly distributed within and around grain boundaries, acting as heterogeneous nucleation centers to promote the development of equiaxed crystals. The pre-added components are elements selected from at least one reinforcing phase from Mn, Si, Cr, Sn, Ti, and Zr; or light rare earth elements or intermetallic compounds formed by light rare earth elements and molten magnesium; or microparticles of porous inert materials; or substances that can reduce the precipitation free energy of the system. The pre-added components are added in the form of metals, intermediate alloys, or metal salts.

[0013] When the magnesium alloy composite material comes into contact with water or an aqueous electrolyte solution, the interaction between water molecules and the porous inert material causes the surface potential of the porous inert material pores and the electrochemical potential of light rare earth or light rare earth magnesium intermetallic compounds to manifest. This allows the microporous inert material in the magnesium alloy composite material to form a complete electrochemical dissolution reaction system with the matrix magnesium phase. In high-mineralization electrolytes ranging from pure water to 250,000 PPM, and at temperatures ranging from 25 to 93°C, the dissolution rate of the magnesium alloy composite material is 10-350 mg / cm³. 2 ·h.

[0014] This application also relates to a method for preparing a magnesium alloy composite material with a micro-battery system, comprising the following steps:

[0015] (1) Prepare a Mg matrix and light rare earth elements or intermetallic compounds formed by light rare earth elements and molten magnesium, wherein the weight content of the Mg matrix is ​​more than 50%.

[0016] (2) A portion of light rare earth elements or intermetallic compounds formed by light rare earth elements and molten magnesium are pre-adsorbed and coated in porous inert materials to form microcapsules;

[0017] (3) Add the microcapsules, Mg matrix and other reinforcing phase additives together into the melting furnace;

[0018] (4) Melt until completely melted, and stir to disperse the microcapsules evenly;

[0019] (5) Cast and cool to obtain magnesium alloy composite material.

[0020] This application also relates to a method for preparing a magnesium alloy composite material with a micro-battery system, comprising the following steps:

[0021] (1) Prepare a Mg matrix and light rare earth elements or intermetallic compounds formed by light rare earth elements and molten magnesium, wherein the weight content of the Mg matrix is ​​more than 50%.

[0022] (2) Add the porous inert material, the reinforcing phase additive, and the material from step (1) together into the melting furnace;

[0023] (3) Melt until completely melted, and stir to ensure uniform dispersion of all components;

[0024] (4) Cast and cool to obtain magnesium alloy composite material.

[0025] This includes at least one subsequent extrusion, forging and rolling deformation treatment, and aging treatment to improve the microstructure or mechanical properties of the material; the intermetallic compound is prepared by direct melt alloying or molten salt electrochemical method.

[0026] The magnesium alloy composite material with a micro-battery system according to this application has the following beneficial technical effects:

[0027] (1) Metallic and / or intermetallic compounds of rare earth elements (such as Mg) 17 La2+, etc., as the cathode phase, form a stable microcouple with the α-Mg matrix of the magnesium alloy, driving continuous dissolution; the dissolution rate in a 3 wt% KCl-water mixture at 90℃ can reach up to 350 mg / cm³. 2 ·h;

[0028] (2) After solidification and cooling, the coating material forms intergranular defects, which constitute additional charge transport channels;

[0029] (3) Pre-added components serve as heterogeneous nucleation centers to promote the development of equiaxed crystals, resulting in a uniform distribution of light rare earth phases and complete dissolution; heterogeneous nucleation can also refine grains and improve mechanical properties. Detailed Implementation

[0031] This application, as an extension of patent No. 202610679250.5, will further elaborate on and provide more refined protection from the perspective of using intermetallic compounds formed by light rare earth elements and magnesium as the cathode phase of micro batteries.

[0032] This application provides a magnesium alloy composite material with a micro-battery system, comprising Mg with a weight content of more than 50%, and further comprising light rare earth elements or intermetallic compounds formed by light rare earth elements and molten magnesium, wherein the weight content of the light rare earth elements or intermetallic compounds formed by light rare earth elements and molten magnesium is between 0.05% and 10% based on the rare earth element content; the light rare earth elements or intermetallic compounds formed by light rare earth elements and molten magnesium have an electrochemical potential difference with the Mg matrix to form a micro-battery system, and more than 50% of the light rare earth-rich cathode phase is distributed around the α-Mg matrix phase. Electron channels that can be activated by water molecules are established between the matrix phases, enabling an electrochemical dissolution reaction circuit to be formed between the rare earth cathode phase and the magnesium matrix phase.

[0033] The intermetallic compounds of this application can be prepared by direct melt alloying or molten salt electrochemical methods. At least 5% of the light rare earth element or the intermetallic compound formed by the light rare earth element and molten magnesium is coated or adsorbed within the porous inert material. This means that at least 5% of the mass of the elemental light rare earth element or the intermetallic compound formed by the light rare earth element and molten magnesium is coated or adsorbed within the porous inert material. During molten cooling, the precipitates are distributed around the α-Mg matrix phase grains of the magnesium alloy composite, forming preferential channels for Mg atoms to lose electrons and transport outwards. Alternatively, the light rare earth element and molten magnesium form a eutectic, hypoeutectic, twinned, or peritectic structure during solidification, resulting in a partially coherent or completely incoherent interface between the precipitated phase and the magnesium matrix.

[0034] When conventional light rare earth elements and other cathode phases are added to magnesium alloy composites, they form eutectic, twinned, or hypoeutectic structures with the α-Mg matrix phase in the form of elemental or intermetallic compounds. Although an electrochemical potential difference exists between the cathode material and the α-Mg matrix phase, its microstructure prevents the formation of an effective micro-electrochemical reaction system, making it difficult to achieve the required solubility and controlled dissolution rate. Only when sufficient cathode additives are placed inside a porous inert material, and the extremely small particles of the porous inert material coated with the cathode phase are distributed around the α-Mg matrix grains under effective control, forming a microstructure with a sufficient electrochemical potential difference and effective electron channels, can the magnesium alloy composite material exhibit good electrochemical dissolution characteristics.

[0035] The key technical features of this application include the following three aspects.

[0036] Metal and intermetal compound micro battery systems

[0037] Utilizing light rare earth elements such as Ce, La, Sm, Pr, Nd, etc., or intermetallic compounds formed by light rare earth elements and molten magnesium, such as Mg. 12 Ce, Mg3Sm, Mg 17 La2 and other metals form micro-cells with the matrix Mg after the alloy cools and solidifies due to the difference in electrochemical potential, resulting in a stable and continuous electrochemical dissolution reaction mechanism. In magnesium alloys, Mg-RE (magnesium-rare earth) intermetallic compounds have a higher self-corrosion potential than the α-Mg matrix phase. When the Mg-RE phase coexists with α-Mg, they form a corrosion couple. The Mg-RE phase acts as the cathode phase, accelerating the anodic dissolution of the α-Mg matrix.

[0038] The intermetallic compounds are prepared by direct melt alloying or molten salt electrochemical methods. That is, rare earth master alloys can be prepared by direct melt alloying, or Mg-La intermetallic compounds, including Mg, can be prepared by electrochemical methods in a LiCl-KCl molten salt system. 17 La2, Mg3La, and MgLa phases. Since the standard electrode potential of La is much more positive than that of Mg, it is difficult to reduce La alone on an inert electrode. Therefore, the core principle is induced co-deposition. When Mg and La are co-reduced on a cathode (such as a molybdenum or tungsten electrode), the newly formed active Mg will form a stable intermetallic compound with La. This process lowers the reduction potential of La, allowing Mg and La to co-deposit at similar potentials. Using a LiCl-KCl eutectic molten salt as the base electrolyte, and adding MgCl2 and LaCl3 (or La2O3) as raw materials, the reaction is usually carried out at high temperatures above 500 degrees Celsius. Taking LiCl-KCl-MgCl2 molten salt as an example, the overall reaction occurring on the cathode (such as a molybdenum or tungsten electrode) can be simplified as follows:

[0039] x Mg²⁺ + y La³⁺ + (2x+3y)e⁻ → Mg x La_y (intermetallic compound)

[0040] Mg-La alloys can be prepared by directly using magnesium as the active electrode, or by using tungsten or molybdenum as the inert working electrode.

[0041] During solidification, Ce, La, Sm, Pr, Nd, etc., can form eutectic, hypoeutectic, twinned, or peritectic structures with Mg. The significant difference between the atomic radii of light rare earth elements (Ce approximately 182.5 pm, La approximately 187.9 pm, Sm approximately 180.4 pm) and the atomic radius of Mg (approximately 160 pm) results in a partially coherent or completely incoherent interfacial relationship between the precipitated phase and the magnesium matrix.

[0042] Simply adding light rare earth elements such as Ce, La, Sm, Pr, and Nd to magnesium alloys cannot directly form a good dissolution mechanism and electrochemical dissolution system. This is because if these light rare earth elements are located inside the crystal of the alloy composite material, they are not sufficiently distributed at the grain boundaries; and simultaneously, a good conductive channel cannot be established between the high electrochemical potential light rare earth element phase and the matrix phase at the grain boundaries, thus the dissolution reaction of the composite material will not occur. This is why this invention selects these light rare earth elements and simultaneously controls the distribution of more than 50% of the light rare earth-rich cathode phase around the α-Mg matrix phase; and uses semi-coherent structures, crystal defects, heterogeneous phases, crystal distortion, porous materials, microcapsules, etc., to establish conductive channels that can be activated by water molecules between the matrix phases, so that a good electrochemical dissolution reaction circuit is formed between the rare earth cathode phase and the magnesium matrix phase.

[0043] Adsorption dispersion technology or coating dispersion technology

[0044] The precipitated phases of light rare earth intermetallic compounds tend to precipitate within crystals, becoming encapsulated by the matrix phase and unable to form a conductive circuit, thus hindering the micro-battery reaction and preventing sustained dissolution. This invention utilizes porous inert materials with large specific surface areas and capillary microstructures, such as diatomaceous earth, kaolin, and porous molecular sieves, to enrich light rare earth elements and their alloys / compounds within porous capillaries. These are then added to a molten magnesium alloy through stirring, dispersion, and condensation crystallization. This allows the light rare earth additives to exist in one or a combination of various forms, such as metals, intermetallic compounds, salts, and ions, around the material's matrix phase. When the magnesium alloy composite material comes into contact with electrolytes such as aqueous solutions, these capillary porous deposited phases, in a water-rich state, become excellent electrical conductors and act as the cathode of the electrochemical micro-battery, enabling sustained and uniform electrochemical dissolution.

[0045] The porous inert material described in this application possesses a capillary microstructure and a large specific surface area, and can be molecular sieves, kaolin, diatomaceous earth, etc. For example, by selecting appropriate porous inert materials such as kaolin or diatomaceous earth, additives containing light rare earth elements are enriched in the capillaries of the porous inert material through adsorption, coating, or semi-coating. Then, the porous inert material enriched with additives is widely distributed in the magnesium alloy composite material. During the smelting process, the coating material protects the additives from oxidation and premature reaction, and simultaneously forms an irregular interface structure between the matrix phase and the precipitated phase after cooling. These interface defects, such as dislocations, vacancies, and steps, constitute preferential channels for Mg atoms to lose electrons and transport outwards.

[0046] The specific surface area of ​​porous inert materials ranges from 200 to 1000 m². 2 Between / g.

[0047] The method of adding porous inert materials is to enrich the additives containing light rare earth elements in the capillary of the porous inert materials in the form of adsorption, coating or semi-coating, so that the porous inert materials enriched with additive materials are widely distributed in the magnesium alloy composite material. Stirring, dispersing and condensing crystallization make the light rare earth additives exist in the surrounding matrix phase in at least one form of metal, intermetallic compound, salt or ion.

[0048] Heterogeneous nucleation technology

[0049] Pre-added heterogeneous components refer to components that, when added, can significantly reduce the free energy of molten magnesium matrix when it precipitates from the liquid state, or the surface tension of its liquid-solid transition during precipitation. These components can be selected from at least one of Mn, Si, Cr, Sn, Ti, Zr, Ce, La, Sm, Pr, Nd, etc., or microparticles of porous inert materials, or additives that can reduce the system's precipitation free energy and phase transformation surface tension. When these additives form intermetallic compounds, these heterogeneous components act as non-spontaneous nucleation centers, uniformly distributed within and around grain boundaries, promoting the development of equiaxed crystals. This ensures that light rare earth intermetallic compounds are widely and uniformly distributed throughout the finished material, achieving uniform, complete, and continuous controlled dissolution. The extensive pre-pre-selection of heterogeneous nucleation centers also contributes to grain refinement, thereby improving the mechanical properties of the alloy and enhancing the material's strength and plasticity. The total amount of pre-added components is 0.05-15% of the total alloy volume.

[0050] As mentioned above, heterogeneous components such as Mn, Si, Cr, Sn, Ti, Zr, Ce, La, Sm, Pr, and Nd, when added to magnesium alloys, can disperse within the crystal structure to strengthen the material and impart high mechanical properties. They can also act as heterogeneous nucleation centers, promoting the development of equiaxed crystals and improving the material's mechanical properties. The pre-added heterogeneous components can be selected from at least one of Mn, Si, Cr, Sn, Ti, Zr, Ce, La, Sm, Pr, and Nd, or as microparticles of porous inert materials, or as additives that can significantly reduce the precipitation free energy and phase transformation surface tension of magnesium. The total addition amount is 0.05-15% of the total alloy weight. The addition can be done as metals; as intermediate alloys such as magnesium-zirconium, magnesium-manganese, and magnesium-titanium; or as metal salts such as manganese chloride. They can be added together with other components to a melting furnace for alloying and then casting, or they can be added after other components have melted. The specific method depends on the process, yield, and state of the additives.

[0051] The magnesium alloy composite material obtained in this application, when in contact with water or water-based electrolyte solutions, exhibits surface potential and electrochemical potential of light rare earth or light rare earth magnesium intermetallic compounds due to the interaction of water molecules with the porous inert material. This allows the microporous inert material in the magnesium alloy composite material to form a complete electrochemical dissolution reaction system with the matrix magnesium phase. In high-mineralization electrolytes ranging from pure water to 250,000 PPM, and at temperatures ranging from 25 to 93°C, the dissolution rate of the magnesium alloy composite material is 10-350 mg / cm³. 2 ·h.

[0052] This application also relates to a method for preparing a magnesium alloy composite material with a micro-battery system, comprising the following steps:

[0053] (1) Prepare a Mg matrix and light rare earth elements or intermetallic compounds formed by light rare earth elements and molten magnesium, wherein the weight content of the Mg matrix is ​​more than 50%.

[0054] (2) A portion of light rare earth elements or intermetallic compounds formed by light rare earth elements and molten magnesium are pre-adsorbed and coated in porous inert materials to form microcapsules;

[0055] (3) Add the microcapsules, Mg matrix and other reinforcing phase additives together into the melting furnace;

[0056] (4) Melt until completely melted, and stir to disperse the microcapsules evenly;

[0057] (5) Cast and cool to obtain magnesium alloy composite material.

[0058] This application also relates to a method for preparing a magnesium alloy composite material with a micro-battery system, comprising the following steps:

[0059] (1) Prepare a Mg matrix and light rare earth elements or intermetallic compounds formed by light rare earth elements and molten magnesium, wherein the weight content of the Mg matrix is ​​more than 50%.

[0060] (2) Add the porous inert material, the reinforcing phase additive, and the material from step (1) together into the melting furnace;

[0061] (3) Melt until completely melted, and stir to ensure uniform dispersion of all components;

[0062] (4) Cast and cool to obtain magnesium alloy composite material.

[0063] It may also include a homogenization heat treatment step, and may include at least one subsequent extrusion, forging and rolling deformation treatment, and aging treatment, in order to improve the microstructure of the material or improve the mechanical properties of the material.

[0064] Example 1: Mg-Zn-La system + coating + heterogeneous nucleation center

[0065] The following components are selected by mass percentage: Mg 93.5%, Zn 3.0%, La 2.5%, Mn 0.8%, and Zr 0.2%, wherein La is in the form of Mg-La30 master alloy, Mn is pre-coated in kaolin in the form of MnCl2 with a shell thickness of about 1-50μm, and Zr is added in the form of Mg-Zr30 master alloy.

[0066] Pre-coated MnCl2 kaolin microcapsules were added to a melting furnace along with magnesium ingots, zinc ingots, and Mg-Zr master alloy. The mixture was melted at 720-750℃ under an SF6+CO2 protective atmosphere until completely melted, with stirring to ensure uniform dispersion of the microcapsules. Magnesium rods were prepared using a semi-continuous casting method, with a cooling rate controlled at 30℃ / s. Subsequently, homogenization heat treatment (480℃×12h), hot extrusion (extrusion ratio 15:1, temperature 380℃), and aging treatment (200℃×24h) were performed.

[0067] Microstructure characterization: SEM observation showed that La was mainly enriched at grain boundaries, forming Mg. 17 The La2 intermetallic compound phase is distributed in a network / granular manner; Mn is dispersed in the crystal as elemental particles, acting as heterogeneous nucleation centers to promote the development of equiaxed crystals, with a grain size of approximately 15-25 μm. The kaolin coating layer is in a semi-dissolved state after smelting, forming irregular interface defects with the matrix, and the voids are rich in La, Mn, and Cl electrolyte substances.

[0068] Performance testing: Tensile strength at room temperature 290 MPa, yield strength 180 MPa, elongation 7%; dissolution rate in 93℃ / 3% KCl 60 mg / cm³ 2 •h; The dissolution mode is uniform dissolution with no honeycomb residue.

[0069] Example 2: Mg-Al-Ce-Sm system (different light rare earth elements)

[0070] The composition by mass percentage is as follows: Mg 90%, Al 4.5%, Ce 3.0%, Sm 1.5%, Ti 0.5%, and Si 0.5%. Ce is pre-prepared as CeO3 in the form of microcapsules coated with diatomaceous earth, with a shell thickness of 1-50 μm. Sm is added in the form of Mg-Sm30 master alloy, and Ti is pre-placed in the form of Ti powder with a particle size of approximately 5-200 μm.

[0071] The smelting process is the same as in Example 1, the casting cooling rate is 50℃ / s, the homogenization treatment is 500℃×16h, the extrusion ratio is 12:1, the temperature is 390℃, and the aging is 220℃×18h.

[0072] Microstructure characterization: Ti and Si particles act as heterogeneous nucleation centers, promoting the development of equiaxed crystals with a grain size of 10-20 μm; Ce / Sm reacts with Mg to form Mg 12 Intermetallic compounds such as Ce and Mg3Sm are uniformly distributed at grain boundaries and within grains, with the uniformity of light rare earth phase distribution improved by approximately 40% compared to the uncoated control. The micropores of the coating material are rich in CeO3. 2+ Electrolyte substances.

[0073] Performance testing: Tensile strength at room temperature 320 MPa, yield strength 200 MPa, elongation 10%; dissolution rate in 93℃ / 3% KCl 90 mg / cm³ 2 •h, no insoluble bulk phase was detected in the residue.

[0074] Example 3: Comparison of different strengthening nucleating agents

[0075] With the base composition fixed as Mg-4.5Al-3Ce-1.5Sm, 0.5% of different reinforcing phase heterogeneous components, such as Mn, Si, Cr, Sn, and Ti, were added respectively, using the same coating and preparation process as in Examples 1 and 2.

[0076] Mn 18 328 11 152 good Si 22 310 9 118 generally Cr 15 345 28 176 good Sr 20 320 10 150 good Ti 12 355 10 198 excellent No addition (control) 45 165 6 65 Poor (localized pitting corrosion)

[0077] The results show that Ti has the best effect on grain refinement and dissolution uniformity improvement, which is related to the high lattice mismatch between Ti and Mg, making it a more effective heterogeneous nucleating agent.

[0078] Although the embodiments disclosed in this application are as described above, the content is merely for the purpose of facilitating understanding of this application and is not intended to limit this application. Any person skilled in the art to which this application pertains may make any modifications and changes in the form and details of the implementation without departing from the spirit and scope disclosed in this application; however, the scope of patent protection of this application shall still be determined by the scope defined in the appended claims.

Claims

1. A magnesium alloy composite material with a micro-battery system, comprising Mg with a weight content of more than 50%, and further comprising light rare earth elements or intermetallic compounds formed by light rare earth elements and molten magnesium, wherein the weight content of the light rare earth elements or intermetallic compounds formed by light rare earth elements and molten magnesium is between 0.05% and 10% based on the rare earth element content; characterized in that, The light rare earth elements or the intermetallic compounds formed by the light rare earth elements and molten magnesium have an electrochemical potential difference with the Mg matrix and form a micro battery system, with more than 50% of the light rare earth-rich cathode phase distributed around the α-Mg matrix phase.

2. The magnesium alloy composite material according to claim 1, characterized in that, At least 5% of the light rare earth elements or intermetallic compounds formed by the light rare earth elements and molten magnesium are coated or adsorbed in the porous inert material. Upon melting and cooling, these elements precipitate and distribute around the α-Mg matrix grains of the magnesium alloy composite, forming preferential channels for Mg atoms to lose electrons and transport outwards; or During solidification, the light rare earth elements and molten magnesium form eutectic, hypoeutectic, twinned, or peritectic structures, resulting in a partially coherent or completely incoherent interface between the precipitated phase and the magnesium matrix.

3. The magnesium alloy composite material according to claim 2, characterized in that, The specific surface area of ​​the porous inert material is between 200 and 1000 m². 2 Between / g.

4. The magnesium alloy composite material according to claim 2 or 3, characterized in that, The porous inert material is added by enriching the additive containing light rare earth elements in the capillary of the porous inert material in the form of adsorption, coating or semi-coating, and then adding the porous inert material enriched with additives into the melt, stirring, dispersing and condensing to crystallize so that the light rare earth additive exists in the vicinity of the matrix phase in at least one of the forms of metal, intermetallic compound, salt and ion.

5. The magnesium alloy composite material according to claim 1 or 2, characterized in that, It also includes pre-added components that serve as non-spontaneous nucleation centers, which are uniformly distributed at grain boundaries and within the grains to promote the development of equiaxed crystals as heterogeneous nucleation centers.

6. The magnesium alloy composite material according to claim 5, characterized in that, The pre-added component is an element selected from at least one reinforcing phase selected from Mn, Si, Cr, Sn, Ti, and Zr, or the light rare earth element or an intermetallic compound formed by the light rare earth element and molten magnesium, or microparticles of porous inert material or a substance that can reduce the precipitation free energy of the system; the pre-added component is added in the form of a metal, an intermediate alloy, or a metal salt.

7. The magnesium alloy composite material according to any one of claims 1-3 and 6, characterized in that, When the magnesium alloy composite material comes into contact with water or an aqueous electrolyte solution, the interaction between water molecules and the porous inert material causes the surface potential of the porous inert material pores and the electrochemical potential of light rare earth or light rare earth magnesium intermetallic compounds to manifest. This allows the microporous inert material in the magnesium alloy composite material to form a complete electrochemical dissolution reaction system with the matrix magnesium phase. In high-mineralization electrolytes ranging from pure water to 250,000 PPM and at temperatures ranging from 25 to 93°C, the dissolution rate of the magnesium alloy composite material is 10-350 mg / cm³. 2 ·h.

8. A method for preparing a magnesium alloy composite material with a micro-battery system, characterized in that, Includes the following steps: (1) Prepare a Mg matrix and light rare earth elements or intermetallic compounds formed by light rare earth elements and molten magnesium, wherein the weight content of the Mg matrix is ​​more than 50%. (2) A portion of light rare earth elements or intermetallic compounds formed by light rare earth elements and molten magnesium are pre-adsorbed and coated in porous inert materials to form microcapsules; (3) Add the microcapsules, Mg matrix and other reinforcing phase additives together into the melting furnace; (4) Melt until completely melted, and stir to disperse the microcapsules evenly; (5) Cast and cool to obtain magnesium alloy composite material.

9. A method for preparing a magnesium alloy composite material with a micro-battery system, characterized in that, Includes the following steps: (1) Prepare a Mg matrix and light rare earth elements or intermetallic compounds formed by light rare earth elements and molten magnesium, wherein the weight content of the Mg matrix is ​​more than 50%. (2) Add the porous inert material, the reinforcing phase additive, and the material from step (1) together into the melting furnace; (3) Melt until completely melted, and stir to ensure uniform dispersion of all components; (4) Cast and cool to obtain magnesium alloy composite material.

10. The preparation method according to claim 8 or 9, characterized in that, It also includes at least one of subsequent extrusion, forging and rolling deformation treatment, and aging treatment to improve the microstructure or mechanical properties of the material; the intermetallic compound is prepared by direct melt alloying or molten salt electrochemical method.