A six-system aluminum alloy material and a preparation method thereof

Abstract

The present application belongs to the field of aluminum alloy material, and particularly relates to a six-system aluminum alloy material and a preparation method thereof; the material comprises aluminum powder, magnesium powder, silicon powder, copper powder, manganese powder, chromium powder, zinc powder, iron powder, titanium powder and two key modifiers, i.e., a nano yttrium zirconium nitride composite grain refiner and an indium gallium silicon composite oxide sintering aid. In the preparation process, firstly, the above raw materials are mixed in a protective atmosphere, and are mixed with a binder to prepare a feedstock, and then a green body is obtained through injection molding. After the green body is subjected to an oxalic acid catalytic degreasing and a hot degreasing step under hydrogen protection, sintering is completed in a protective atmosphere, and finally, the finished product is obtained through solid solution treatment, water quenching and aging treatment. Through the synergistic effect of the two modified compounds, the alloy grain is significantly refined and the sintering densification degree is improved, and finally, the six-system aluminum alloy material has excellent mechanical strength, corrosion resistance and dimensional stability, and is particularly suitable for the field of medical materials with strict performance requirements.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of aluminum alloy materials, and particularly relates to a six-system aluminum alloy material and a preparation method thereof. BACKGROUND

[0002] As a heat-treatable strengthening aluminum alloy system, the six-system aluminum alloy has been widely used in the industrial field. The six-system aluminum alloy takes magnesium and silicon as main alloying elements, and obtains good comprehensive performance through the formation of strengthening phases after aging treatment. Traditional casting, extrusion and forging processes are mature in the production of the six-system aluminum alloy, and can meet the needs of most structural parts and functional parts. However, with the development of medical devices towards light weight, precision and complexity, higher requirements are put forward for the forming precision, mechanical properties and biocompatibility of aluminum alloy materials. Especially in the production of medical devices with complex internal cavities and microstructures, the traditional subtractive manufacturing method faces the limitations of low material utilization rate and difficult control of processing stress, and the conventional powder metallurgy technology is difficult to ensure high density and high dimensional accuracy at the same time. Although the metal injection molding technology can realize the near-net-shape forming of complex structural parts, when applied to aluminum alloy, the existence of the dense oxide layer on the surface of aluminum powder seriously hinders the mass transfer and densification process in the sintering process, resulting in a significant gap in mechanical properties compared with traditional processes, which becomes the main technical bottleneck in the popularization of the technology in high-end medical aluminum alloy products.

[0003] In the field of medical materials, the material not only needs to meet the basic mechanical property requirements, but also must have excellent biocompatibility and corrosion resistance in the body environment. Although the existing six-system aluminum alloy can meet part of the medical needs to some extent through composition optimization and process adjustment, it still faces many challenges in long-term implantation applications. For example, the conventional grain refiner is prone to coarsening or failure in the high-temperature sintering process of the metal injection molding process, which cannot effectively inhibit the grain growth, resulting in insufficient material strength; and the commonly used sintering aid may introduce elements or phase compositions harmful to the human body, affecting the biological safety of the material. In addition, medical materials have high requirements for surface quality, dimensional stability and batch consistency, and any small defect or performance fluctuation may cause the failure of the device function or trigger adverse biological reactions. Therefore, developing new modified additives, which can effectively solve the densification problem in the aluminum alloy metal injection molding process without increasing the cost too much, and can ensure that the material meets the performance requirements of the medical grade, has become an urgent need for the technical development in the current field.

[0004] In recent years, researchers have tried to improve the metal injection molding performance of six series aluminum alloy through various ways, including optimizing powder characteristics, adjusting binder system, improving debinding and sintering process, etc. Studies have shown that adding appropriate grain refiner to the alloy can effectively improve the microstructure of the sintered body, and appropriate sintering aids can promote the densification process. However, the addition of a single component of the additive often cannot solve the problems of grain coarsening and insufficient densification at the same time; and the physical mixing of multiple additives may lead to uneven composition distribution and introduce secondary defects. More importantly, the additive suitable for medical materials must consider its long-term safety in the body to avoid cytotoxicity caused by decomposition or leaching of the additive. Therefore, the design and development of a new type of composite additive system that can be well compatible with the aluminum alloy matrix, play a synergistic role in the sintering process and meet the medical safety standards, has become the key to breaking through the existing technical bottleneck, which is also the core innovation point of the present invention and the urgent technical problem to be solved. SUMMARY

[0005] In view of the shortcomings of the prior art, the purpose of the present application is to provide a six series aluminum alloy material and a preparation method thereof.

[0006] In the first aspect of the present application, a preparation method of a six series aluminum alloy material is provided, comprising the following steps:

[0007] S1, placing aluminum powder, magnesium powder, silicon powder, copper powder, manganese powder, chromium powder, zinc powder, iron powder, titanium powder, and nano yttrium zirconium nitride composite grain refiner and indium gallium silicon composite oxide sintering aid in a mixer, mixing under argon protection to obtain mixed metal powder; mixing the mixed metal powder with a binder in a banbury mixer at 150-170 DEG C to obtain a feedstock;

[0008] S2, injecting the feedstock into a precision mold, injection molding at 74-76 DEG C to obtain a green body; placing the green body in an oxalic acid catalytic debinding furnace, debinding in an oxalic acid atmosphere at 115-125 DEG C; obtaining a body, heating the body to 450-550 DEG C under hydrogen atmosphere, and holding; transferring to a high temperature sintering furnace, heating to 625-635 DEG C under nitrogen protection atmosphere, and sintering; after sintering, solid solution treatment at 534-536 DEG C, then water quenching, and then aging treatment at 174-176 DEG C; finally, finishing.

[0009] As a preferred technical solution of the present application, the binder is a polyformaldehyde-based binder system, and the specific composition and mass ratio are as follows: polyformaldehyde 65%, low density polyethylene 25%, polyethylene glycol 6%, stearic acid 3%, and antioxidant 1%.

[0010] As a preferred technical scheme of the present application, the antioxidant is a composite system composed of hindered phenolic antioxidant and phosphite antioxidant; it is composed of tetra[β-(3,5-di-tert-butyl-4-hydroxyphenyl) propionic acid] pentaerythritol ester and tris(2,4-di-tert-butylphenyl) phosphite; the mass ratio of tetra[β-(3,5-di-tert-butyl-4-hydroxyphenyl) propionic acid] pentaerythritol ester and tris(2,4-di-tert-butylphenyl) phosphite is 1:1. The composite antioxidant system effectively inhibits the thermal oxidative degradation of polyformaldehyde and polyethylene in the mixing process at 150-170°C through the synergistic effect of free radical capture and hydrogen peroxide decomposition, ensuring the component stability and rheological properties of the feedstock under high-temperature processing conditions.

[0011] In the present application, the overall preparation reaction mechanism of the six-system aluminum alloy material is a complex process involving powder metallurgy, interface reaction and solid phase transformation. In the initial stage, the basic components such as aluminum powder, magnesium powder, silicon powder and two self-made modifiers are mechanically mixed for a long time in a protective atmosphere. The mechanism of this process is to achieve the macroscopic and microscopic uniform distribution of various powder particles through physical force, especially to make the nano-sized refiner and sintering aid fully adhere to the surface and gap of relatively coarse aluminum powder particles, creating uniform initial conditions for subsequent chemical reactions. The mixing of the binder and injection molding is the stage of giving the material shape, and the mechanism is that the thermoplastic binder wraps all the metal powder particles after melting, forming a uniform feed with good fluidity, and filling the mold cavity under pressure, and then setting after cooling. The subsequent oxalic acid catalytic debinding is the first key chemical change, and the gaseous oxalic acid penetrates into the green body and reacts with the polyformaldehyde-based binder to break the macromolecular chain into low molecular weight formaldehyde and volatilize, which can completely maintain the relative position of the powder particles. Then, the thermal debinding in hydrogen, the mechanism is to rely on the reducing atmosphere and heat energy of hydrogen to completely decompose the residual binder skeleton and remove the trace carbon in the system, and hydrogen has a certain reduction and damage effect on the original aluminum oxide film on the surface of aluminum powder, which preliminarily activates the powder surface. In the high-temperature sintering stage, the core mechanism is the combination of solid-state sintering and liquid-phase sintering: the indium-gallium-silicon composite oxide sintering aid reacts with aluminum, magnesium and other elements to form a low-melting-point eutectic liquid phase at a certain temperature, which rearranges the particles through capillary force, and greatly promotes surface diffusion and grain boundary diffusion, drives the neck between particles to grow and the pores to shrink, and realizes densification; At the same time, nano yttrium zirconium nitride particles remain stable at high temperature and pin on the aluminum grain boundary, strongly hindering grain boundary migration and inhibiting abnormal grain growth at high temperature, thereby obtaining a fine sintered structure. The final solid solution and aging heat treatment is the classic precipitation strengthening mechanism, first dissolving the alloying elements such as magnesium and silicon into the aluminum matrix to form a supersaturated solid solution at a higher temperature, and then quenching to freeze it; Subsequently, aging at a lower temperature, the supersaturated solid solution becomes unstable and precipitates in the form of extremely fine dispersed reinforcement phase, which can effectively hinder dislocation movement, thereby finally making the material obtain high strength and high hardness.

[0012] As a preferred technical scheme of the present application, the mixing time in step S1 is 4-6h under argon protection.

[0013] As a preferred technical scheme of the present application, the sintering time in step S2 is 2-4h when heated to 625-635℃.

[0014] As a preferred technical scheme of the present application, the preparation method of the nano yttrium zirconium nitride composite grain refiner comprises: A1, dissolving yttrium nitrate and zirconium oxynitrate in deionized water to obtain a salt solution; the salt solution is added dropwise into a precipitant containing ammonia under stirring, the pH value of the solution is kept at 9-10, and yttrium zirconium hydroxide co-precipitate is obtained; the yttrium zirconium hydroxide co-precipitate is vacuum filtered and washed with deionized water to obtain washed precipitate, and the washed precipitate is dried in a vacuum drying oven at 78-82℃ to obtain yttrium zirconium hydroxide precursor; A2, the yttrium zirconium hydroxide precursor is transferred to a tube furnace, heated to 795-805℃ under ammonia atmosphere, and naturally cooled to room temperature to obtain nano yttrium zirconium nitride composite powder; the nano yttrium zirconium nitride composite powder is ball milled under argon protection.

[0015] In the present application, the preparation process of the nano yttrium zirconium nitride composite grain refiner is essentially a combination of wet chemical co-precipitation and high-temperature nitriding, which constructs a kind of nano composite ceramic particles that are stable in aluminum melt and can provide efficient heterogeneous nucleation sites. Its reaction mechanism begins in the aqueous solution environment, yttrium ions and zirconium ions dissociated from yttrium nitrate and zirconium oxynitrate, under the alkaline conditions provided by ammonia, hydrolysis and co-precipitation occur synchronously to generate amorphous yttrium zirconium hydroxide co-precipitate, this process ensures the high uniform mixing of yttrium and zirconium elements at atomic scale, laying a solid foundation for the subsequent formation of uniform composite nitride. Subsequently, the precursor obtained after washing and drying is subjected to high-temperature treatment under flowing ammonia atmosphere, the mechanism of this stage is extremely critical: ammonia decomposes to produce highly active atomic nitrogen at high temperature, these active nitrogen atoms will gradually penetrate and replace the oxygen atoms in the precursor hydroxide, and a deep solid-phase reaction occurs, finally converting it into a thermodynamically more stable yttrium zirconium nitride composite phase. The subsequent high-energy ball milling process is not only to reduce the particle size of the powder, but also a mechanical activation process, which impacts the powder with huge mechanical energy, on the one hand, it breaks the slight sintering agglomeration that may be formed during the nitriding process, obtaining nano powder with uniform particle size distribution; on the other hand, it introduces a large number of crystal defects into the particles and greatly increases the specific surface area, thereby significantly improving the surface activity and dispersibility of the refiner particles in the subsequent aluminum alloy melt, making them become the ideal substrate for non-uniform nucleation of aluminum nuclei, greatly improving the nucleation rate.

[0016] As a preferred technical scheme of the present application, in step A1, the drying time in the vacuum drying oven at 78-82℃ is 12-14h.

[0017] As a preferred technical scheme of the present application, in step A2, the heating temperature is 795-805℃, and the holding time is 2-4h.

[0018] As a preferred technical scheme of the present application, the preparation method of the indium gallium silicon composite oxide sintering aid comprises: B1, dissolving indium nitrate, gallium nitrate and tetraethyl orthosilicate in anhydrous ethanol, adding acetylacetone, stirring and refluxing in a 58-62℃ water bath to obtain a complex solution; adding polyethylene glycol to the complex solution and continuing to stir at 58-62℃ to obtain a reaction solution; B2, transferring the reaction solution to a high-pressure reaction kettle, carrying out solvothermal treatment at 118-122℃, and obtaining a colloidal solution after cooling; concentrating the colloidal solution in a rotary evaporator at 58-62℃, then adding n-hexane, and obtaining a gel product by centrifugal separation; drying the gel product in a vacuum drying oven at 38-42℃, grinding, and obtaining a ground powder; then calcining the ground powder at 400-500℃ in an air atmosphere.

[0019] In the present application, the preparation reaction mechanism of the indium gallium silicon composite oxide sintering aid is based on the principles of sol-gel and complex chemistry, aiming to synthesize a kind of nano composite oxide that can activate the sintering power at the sintering temperature of aluminum alloy. The mechanism starts from the initial hydrolysis of metal cations provided by indium nitrate and gallium nitrate with tetraethyl orthosilicate in ethanol solution, then acetylacetone as a strong complexing agent quickly intervenes, the carbonyl and enol structure in its molecule can form a stable five-membered ring chelate with indium ions and gallium ions, this complexation effectively inhibits the independent hydrolysis and precipitation rate of different metal ions, forcing them to achieve uniform mixing and bonding at the molecular level. After adding polyethylene glycol, its long-chain molecules further stabilize the above-mentioned metal complexes through steric hindrance effect, preventing premature aggregation and precipitation. The next solvothermal step is a key turning point, under the synergistic effect of high temperature and high pressure, the energy of the reaction system is significantly improved, greatly accelerating the further hydrolysis and polycondensation reaction of the complex, promoting the connection between silicate and metal complex through oxygen bridge to form inorganic-organic hybrid gel with three-dimensional network structure. The final calcination process is a phase transition and purification process, in the air, organic components such as acetylacetone and polyethylene glycol are completely oxidized and volatilized, while the residual inorganic components undergo lattice rearrangement and grain growth, finally transforming into a nano composite oxide composed of indium, gallium and silicon oxides, with high specific surface area and chemical activity. The product can effectively destroy the oxide film on the surface of aluminum powder through interfacial reaction in subsequent sintering, greatly promoting material migration and diffusion.

[0020] As a preferred technical scheme of the present application, in step B1, the stirring and refluxing time in the 58-62℃ water bath is 1-2h.

[0021] As a preferred technical scheme of the present application, in step B2, the solvothermal treatment time at 118-122℃ is 6-8h.

[0022] The second aspect of the present application provides a six-system aluminum alloy material prepared by the preparation method of the six-system aluminum alloy material, which comprises the following raw materials in parts by weight: 85-92 parts of aluminum powder; 0.6-1.2 parts of magnesium powder; 0.5-1.2 parts of silicon powder; 0.1-0.5 parts of copper powder; 0.05-0.3 parts of manganese powder; 0.05-0.2 parts of chromium powder; 0.05-0.15 parts of zinc powder; 0.1-0.2 parts of iron powder; 0.05-0.1 parts of titanium powder; 0.1-0.5 parts of nano yttrium zirconium nitride composite grain refiner; 0.2-0.8 parts of indium gallium silicon composite oxide sintering aid; and 8-15 parts of binder.

[0023] Compared with the prior art, the present application has the following beneficial effects:

[0024] (1) The six-system aluminum alloy material and the preparation method thereof provided by the present application have significant technical progress and excellent comprehensive performance. First, in terms of material microstructure and mechanical properties, by introducing the independently developed nano yttrium zirconium nitride composite grain refiner and indium gallium silicon composite oxide sintering aid, fine regulation and control of the alloy organizational structure are achieved. The nano yttrium zirconium nitride composite grain refiner provides a large number of efficient heterogeneous nucleation cores during alloy solidification, significantly reduces the grain size, and greatly increases the grain boundary area, thereby effectively hindering dislocation movement and improving material strength. At the same time, the indium gallium silicon composite oxide sintering aid promotes material transmission by forming a transition liquid phase during sintering, significantly improves the sintering densification degree, eliminates internal pore defects, and makes the material maintain good ductility while significantly improving the tensile strength and yield strength. This unique composite additive system also improves the uniformity of the distribution of the strengthening phase, so that the material can obtain more uniform and fine precipitates after heat treatment, further enhancing the precipitation strengthening effect.

[0025] (2) In terms of process performance and forming precision, the present application successfully solves the worldwide problem of the aluminum alloy powder surface oxide layer hindering sintering by optimizing the metal injection molding process parameters and combining oxalic acid catalytic debinding and staged thermal debinding process. The special debinding process not only effectively removes the binder components, but also removes the oxide film on the surface of the aluminum powder through chemical reaction, creating favorable conditions for atomic diffusion and particle bonding in the subsequent sintering process. The synergistic effect of the two modified compounds significantly reduces the sintering activation energy, enabling full densification at relatively low sintering temperatures, avoiding the problem of grain coarsening caused by excessively high temperatures. This optimized process combination ensures that the product has high dimensional stability, low deformation rate and excellent surface quality, which can meet the stringent size requirements of medical materials for precision components, while greatly reducing the subsequent mechanical processing allowance, improving material utilization and production efficiency.

[0026] (3) In the comprehensive application performance, the six-system aluminum alloy material prepared by the application exhibits excellent performance balance. Due to the grain refinement and the improvement of the density, the material not only has excellent static mechanical properties, but also shows good fatigue strength and wear resistance, which can meet the reliability requirements of long-term service. Through reasonable composition design and process control, the material maintains the inherent good corrosion resistance of the six-system aluminum alloy, and further enhances the stress corrosion resistance by refining the grains. It is particularly worth pointing out that the unique microstructure formed in the sintering process of the material makes it have uniform anodizing characteristics, and the coating quality after surface treatment is significantly better than that of the aluminum alloy produced by the traditional process. These comprehensive performance advantages make the material particularly suitable for manufacturing surgical instruments, orthopedic implants and other high-value medical products. While maintaining the lightweight characteristics, it can meet the multiple standards of the material biocompatibility, mechanical properties and durability of medical devices, showing broad application prospects and significant technical and economic benefits. DETAILED DESCRIPTION

[0027] In order to facilitate the understanding of the present application, the present application is illustrated as follows. Those skilled in the art should understand that the examples are only to help understand the present application, and should not be regarded as specific limitations of the present application.

[0028] Some components in the examples and comparative examples are as follows:

[0029] The aluminum powder is purchased from Hunan Xinghe Science and Technology Co., Ltd.

[0030] The magnesium powder is purchased from Ningxia Zhongse New Material Co., Ltd.

[0031] The silicon powder is purchased from Hesheng Silicon Industry Co., Ltd.

[0032] The copper powder is purchased from Youyan Metal Technology Co., Ltd.

[0033] The manganese powder is purchased from CITIC Daman Mining Industry Co., Ltd.

[0034] The chromium powder is purchased from Qinghe County Ruijiang Metal Material Co., Ltd.

[0035] The zinc powder is purchased from Huludao Zinc Industry Co., Ltd.

[0036] The iron powder is purchased from Hebei Yuehan Metal Material Sales Co., Ltd.

[0037] The titanium powder is purchased from Baotai Group Co., Ltd.

[0038] The oxalic acid is purchased from Shandong Guotai Chemical Co., Ltd.

[0039] The oxalic acid catalytic degreasing furnace is purchased from Shenzhen Zhanxin Furnace Co., Ltd.

[0040] The yttrium nitrate was purchased from Jiangyin Jiuhua New Material Co., Ltd.

[0041] The zirconyl nitrate was purchased from Guangdong Dongfang Zirconium Technology Co., Ltd.

[0042] The indium nitrate was purchased from Zhongye Nanfang Rare Earth Technology Co., Ltd.

[0043] The gallium nitrate was purchased from Zhengzhou Nonferrous Metals Research Institute Co., Ltd.

[0044] The tetraethyl orthosilicate was purchased from Zhejiang Xianan Chemical Group Co., Ltd.

[0045] The acetylacetone was purchased from Araldin Reagent (Shanghai) Co., Ltd.

[0046] The polyethylene glycol was purchased from China Petroleum & Chemical Corporation.

[0047] Example 1

[0048] The embodiment provides a preparation method of a six-system aluminum alloy material, and the specific implementation steps are as follows: firstly, a nano yttrium zirconium nitride composite grain refiner is prepared, 10.00g of analytically pure yttrium nitrate and 10.00g of analytically pure zirconyl nitrate are accurately weighed and placed in a 500ml beaker, 500ml of deionized water is added, and stirring is performed on a magnetic stirrer at a speed of 800rpm until complete dissolution to form a transparent salt solution; 100ml of analytically pure ammonia water with a concentration of 25% is poured into a 1000ml three-necked flask as a precipitating agent, a pH meter probe is installed and placed in a constant temperature water bath to keep 25℃; a peristaltic pump is used to slowly drop the salt solution into the ammonia water precipitating agent at a rate of 5ml / min, while a mechanical stirrer is used to continuously stir at a speed of 600rpm, and the ammonia water addition amount is controlled by an automatic titrator to accurately stabilize the solution pH value at 9.5±0.1; after the dropping is completed, the stirring is continued for 2 hours to completely precipitate the reaction, and a white milky yttrium zirconium hydroxide co-precipitation suspension is obtained; the suspension is poured into a Buchner funnel and vacuum filtration is performed using a 0.22μm microporous filter membrane, the vacuum degree is kept at-0.08MPa, and then the precipitate is washed with 500ml of deionized water for three times; the washed precipitate is transferred to a vacuum drying oven and dried at 80℃ and-0.1MPa vacuum for 13 hours to obtain a light yellow yttrium zirconium hydroxide precursor; 10g of the precursor is placed in a corundum crucible, and the temperature is raised from room temperature to 800℃ at a rate of 5℃ / min in a tubular atmosphere furnace, the ammonia gas atmosphere is kept at a gas flow rate of 200ml / min, the heating is stopped after 3 hours of heat preservation, and the furnace is naturally cooled to room temperature; the obtained light gray nano yttrium zirconium nitride composite powder and zirconia grinding balls with a diameter of 5mm are loaded into a ball mill tank at a mass ratio of 1:20, and ball milling is performed at a speed of 300rpm for 4 hours under argon protection, and the final nano yttrium zirconium nitride composite grain refiner is obtained by passing through a 400 mesh sieve.

[0049] Then the preparation of indium gallium silicon composite oxide sintering aid is carried out, 5.00 g of analytical pure indium nitrate, 5.00 g of analytical pure gallium nitrate and 5.00 g of analytical pure tetraethyl orthosilicate are accurately weighed into a 500 ml round-bottom flask, 200 ml of anhydrous ethanol is added, a condensation reflux device is installed, and stirring is carried out in a 60°C water bath at a speed of 500 rpm until complete dissolution; 2.00 g of analytical pure acetylacetone is added, and stirring and refluxing are continued for 1.5 hours to obtain a light yellow transparent complex solution; 1.00 g of polyethylene glycol with a molecular weight of 6000 is added, and stirring is continued at 60°C for 1 hour to obtain a uniform reaction solution; the reaction solution is transferred to a 500 ml polytetrafluoroethylene-lined high-pressure reaction kettle, placed in an oven, and subjected to solvothermal treatment at 120°C for 7 hours; after natural cooling to room temperature, a milky white colloidal solution is obtained, the colloidal solution is transferred to a rotary evaporator, concentrated to 50 ml under the conditions of a 60°C water bath, a stirring speed of 80 rpm and a vacuum of-0.08 MPa, 100 ml of analytical pure n-hexane is added, and centrifugation is carried out at a speed of 8000 rpm for 10 minutes in a centrifuge, and the bottom gel product is collected; the gel product is spread on a culture dish and dried in a vacuum drying oven at 40°C for 12 hours, and then taken out and ground in a jade mortar for 30 minutes; the ground powder is placed in a muffle furnace, heated to 450°C at a rate of 2°C / min, and calcined for 4 hours to obtain a white indium gallium silicon composite oxide sintering aid.

[0050] Finally, the six-system aluminum alloy material is prepared, and each component is accurately weighed according to the following ratio: 90.00 g of 99.9% purity aluminum powder, 1.00 g of 99.9% purity magnesium powder, 1.00 g of 99.9% purity silicon powder, 0.30 g of 99.9% purity copper powder, 0.20 g of 99.9% purity manganese powder, 0.10 g of 99.9% purity chromium powder, 0.10 g of 99.9% purity zinc powder, 0.15 g of 99.9% purity iron powder, 0.08 g of 99.9% purity titanium powder, 0.30 g of the above-prepared nano yttrium zirconium nitride composite grain refiner, and 0.50 g of indium-gallium-silicon composite oxide sintering aid; all raw materials are placed in a V-type mixer, argon gas is filled, and mixing is performed at a speed of 50 rpm for 5 hours; the uniformly mixed metal powder is added to a banbury mixer together with 10.00 g of a binder, and mixing is performed at a temperature of 160°C and a speed of 40 rpm for 2 hours to obtain uniform feedstock; the feedstock is injected into a precision mold, and injection molding is performed at a temperature of 75°C and a pressure of 50 MPa, with pressure being maintained for 5 minutes to obtain a green body; the green body is placed in an oxalic acid catalytic degreasing furnace, and degreasing is performed at a temperature of 120°C and in an oxalic acid atmosphere of 0.5 mol / L for 4 hours; the degreased body is placed in a hydrogen atmosphere sintering furnace, heated to 500°C at a rate of 5°C / min, and held for 2 hours; then it is transferred to a high-temperature sintering furnace, heated to 630°C at a rate of 10°C / min under nitrogen protection, and sintered for 3 hours; immediately after sintering, the sample is placed in a 535°C salt bath furnace for solid solution treatment for 1 hour, and then rapidly water quenched to room temperature; the sample is then placed in an oven at 175°C for aging treatment for 8 hours; finally, precision machining is performed on a numerical control machine tool, including turning, milling, and polishing processes, to obtain the final six-system aluminum alloy material product.

[0051] Example 2

[0052] The embodiment is different from embodiment 1 in that the preparation of the nano yttrium zirconium nitride composite grain refiner is firstly carried out: 8 g of yttrium nitrate and 8 g of zirconium oxide nitrate are dissolved in 400 ml of deionized water to obtain a salt solution; the salt solution is added dropwise into a precipitant containing 80 ml of ammonia water under stirring to keep the pH value of the solution at 9 to obtain yttrium zirconium hydroxide coprecipitate; the yttrium zirconium hydroxide coprecipitate is vacuum filtered and washed with deionized water for 3 times to obtain washed precipitate, which is dried in a vacuum drying oven at 78℃ for 14 h to obtain yttrium zirconium hydroxide precursor; the yttrium zirconium hydroxide precursor is transferred into a tube furnace, heated to 795℃ under ammonia atmosphere for 4 h, and naturally cooled to room temperature to obtain nano yttrium zirconium nitride composite powder; the nano yttrium zirconium nitride composite powder is ball milled under argon protection for 4 h. The preparation of indium gallium silicon composite oxide sintering aid: 4 g of indium nitrate, 4 g of gallium nitrate and 4 g of tetraethyl orthosilicate are dissolved in 150 ml of anhydrous ethanol, 1.5 g of acetylacetone is added, and the solution is stirred and refluxed in a water bath at 58℃ for 2 h to obtain a complex solution; 0.8 g of polyethylene glycol is added to the complex solution, and the stirring is continued at 58℃ for 1 h to obtain a reaction solution; the reaction solution is transferred into a high-pressure reaction kettle and treated by solvothermal method at 118℃ for 8 h to obtain a colloidal solution; the colloidal solution is concentrated to 40 ml at 58℃ in a rotary evaporator, then 80 ml of n-hexane is added, and the gel product is obtained by centrifugal separation; the gel product is dried in a vacuum drying oven at 38℃ for 14 h, and then ground to obtain the ground powder; then the ground powder is calcined at 400℃ in air atmosphere for 5 h. The preparation of the six-system aluminum alloy material: 85 g of aluminum powder, 0.6 g of magnesium powder, 0.5 g of silicon powder, 0.1 g of copper powder, 0.05 g of manganese powder, 0.05 g of chromium powder, 0.05 g of zinc powder, 0.1 g of iron powder, 0.05 g of titanium powder, 0.1 g of nano yttrium zirconium nitride composite grain refiner and 0.2 g of indium gallium silicon composite oxide sintering aid are placed in a mixer and mixed under argon protection for 4 h to obtain mixed metal powder; the mixed metal powder and 8 g of binder are mixed in a banbury mixer at 150℃ for 2 h to obtain a feedstock; the feedstock is injected into a precision mold and injection molded at 74℃ to obtain a green body; the green body is placed in an oxalic acid catalytic degreasing furnace and degreased in oxalic acid atmosphere at 115℃ for 5 h to obtain a blank; the blank is heated to 450℃ in hydrogen atmosphere and kept for 3 h; then it is transferred into a high-temperature sintering furnace and sintered at 625℃ in nitrogen protection atmosphere for 4 h; after sintering, the blank is subjected to solid solution treatment at 534℃ for 1.5 h, then water quenched, and then aged at 174℃ for 10 h; finally, the blank is finished.

[0053] Embodiment 3

[0054] The difference between this embodiment and Embodiment 1 is that the nano-yttrium zirconium nitride composite grain refiner is prepared first: 12g of yttrium nitrate and 12g of zirconium oxynitrate are dissolved in 600ml of deionized water to obtain a salt solution; the salt solution is added dropwise to a precipitant containing 120ml of ammonia water under stirring, maintaining the pH of the solution at 10, to obtain a yttrium zirconium hydroxide coprecipitate; the yttrium zirconium hydroxide coprecipitate is vacuum filtered and washed three times with deionized water to obtain a clean precipitate; the clean precipitate is dried in a vacuum drying oven at 82℃ for 12h to obtain a yttrium zirconium hydroxide precursor; the yttrium zirconium hydroxide precursor is transferred to a tube furnace and heated to 805℃ for 2h under an ammonia atmosphere, and then naturally cooled to room temperature to obtain nano-yttrium zirconium nitride composite powder; the nano-yttrium zirconium nitride composite powder is ball-milled for 4h under argon protection. Preparation of indium gallium silicon composite oxide sintering aid: 6g indium nitrate, 6g gallium nitrate, and 6g tetraethyl orthosilicate were dissolved in 250ml anhydrous ethanol, and 2.5g acetylacetone was added. The mixture was stirred and refluxed in a water bath at 62℃ for 1h to obtain a complex solution. 1.2g polyethylene glycol was added to the complex solution, and the mixture was stirred at 62℃ for another 1h to obtain a reaction solution. The reaction solution was transferred to a high-pressure reactor and solvated at 122℃ for 6h. After cooling, a colloidal solution was obtained. The colloidal solution was concentrated to 60ml in a rotary evaporator at 62℃, and then 120ml of n-hexane was added. The gel product was obtained by centrifugation. The gel product was dried in a vacuum drying oven at 42℃ for 10h and then ground to obtain a ground powder. The ground powder was then calcined at 500℃ for 3h in air atmosphere. Preparation of 6-series aluminum alloy materials: 92g aluminum powder, 1.2g magnesium powder, 1.2g silicon powder, 0.5g copper powder, 0.3g manganese powder, 0.2g chromium powder, 0.15g zinc powder, 0.2g iron powder, 0.1g titanium powder, 0.5g nano-yttrium zirconium nitride composite grain refiner, and 0.8g indium gallium silicon composite oxide sintering aid were placed in a mixer and mixed for 6 hours under argon protection to obtain mixed metal powder; the mixed metal powder was then mixed with 15g binder in a Banbury mixer at 170℃ for 2 hours to obtain... Feed the material; inject the material into a precision mold and perform injection molding at 76°C to obtain a green body; place the green body in an oxalic acid catalytic degreasing furnace and degrease it in an oxalic acid atmosphere at 125°C for 3 hours; obtain a blank body, heat the blank body to 550°C in a hydrogen atmosphere and hold it for 1 hour; transfer it to a high-temperature sintering furnace and sinter it at 635°C for 2 hours in a nitrogen protective atmosphere; after sintering, perform solution treatment at 536°C for 0.5 hours, then water quench it, and then age it at 176°C for 6 hours; finally, perform finishing.

[0055] Comparative Example 1

[0056] The difference between this comparative example and Example 1 is that 90 g of aluminum powder, 1.0 g of magnesium powder, 1.0 g of silicon powder, 0.3 g of copper powder, 0.2 g of manganese powder, 0.1 g of chromium powder, 0.1 g of zinc powder, 0.15 g of iron powder, 0.08 g of titanium powder, and 0 g of nano yttrium zirconium nitride composite grain refiner and 0.5 g of indium gallium silicon composite oxide sintering aid are placed in a mixer and mixed for 5 h under argon protection to obtain a mixed metal powder; the mixed metal powder is mixed with 10 g of a binder in an internal mixer at 160 °C for 2 h to obtain a feedstock; the feedstock is injected into a precision mold and injection molded at 75 °C to obtain a green body; the green body is placed in an oxalic acid catalytic debinding furnace and debound in an oxalic acid atmosphere at 120 °C for 4 h; a body is obtained, which is heated to 500 °C under a hydrogen atmosphere and held for 2 h; it is transferred to a high-temperature sintering furnace and heated to 630 °C under a nitrogen protective atmosphere and sintered for 3 h; after sintering is completed, it is solution treated at 535 °C for 1 h, then water quenched, and then aged at 175 °C for 8 h; finally, it is finished.

[0057] Comparative Example 2

[0058] The difference between this comparative example and Example 1 is that 90 g of aluminum powder, 1.0 g of magnesium powder, 1.0 g of silicon powder, 0.3 g of copper powder, 0.2 g of manganese powder, 0.1 g of chromium powder, 0.1 g of zinc powder, 0.15 g of iron powder, 0.08 g of titanium powder, and 0.3 g of nano yttrium zirconium nitride composite grain refiner and 0 g of indium gallium silicon composite oxide sintering aid are placed in a mixer and mixed for 5 h under argon protection to obtain a mixed metal powder; the mixed metal powder is mixed with 10 g of a binder in an internal mixer at 160 °C for 2 h to obtain a feedstock; the feedstock is injected into a precision mold and injection molded at 75 °C to obtain a green body; the green body is placed in an oxalic acid catalytic debinding furnace and debound in an oxalic acid atmosphere at 120 °C for 4 h; a body is obtained, which is heated to 500 °C under a hydrogen atmosphere and held for 2 h; it is transferred to a high-temperature sintering furnace and heated to 630 °C under a nitrogen protective atmosphere and sintered for 3 h; after sintering is completed, it is solution treated at 535 °C for 1 h, then water quenched, and then aged at 175 °C for 8 h; finally, it is finished.

[0059] Comparative Example 3

[0060] The comparative example differs from Example 1 in that 90 g of aluminum powder, 1.0 g of magnesium powder, 1.0 g of silicon powder, 0.3 g of copper powder, 0.2 g of manganese powder, 0.1 g of chromium powder, 0.1 g of zinc powder, 0.15 g of iron powder, 0.08 g of titanium powder, 0 g of nano yttrium zirconium nitride composite grain refiner, and 0 g of indium gallium silicon composite oxide sintering aid are placed in a mixer and mixed for 5 h under argon protection to obtain a mixed metal powder; the mixed metal powder and 10 g of a binder are mixed in a banbury mixer at 160 °C for 2 h to obtain a feedstock; the feedstock is injected into a precision mold and injection molded at 75 °C to obtain a green body; the green body is placed in an oxalic acid catalytic degreasing furnace and degreased in an oxalic acid atmosphere at 120 °C for 4 h; a compact is obtained, which is heated to 500 °C under a hydrogen atmosphere and held for 2 h; the compact is transferred to a high-temperature sintering furnace and sintered at 630 °C under a nitrogen protective atmosphere for 3 h; after sintering, the compact is solution treated at 535 °C for 1 h, then water quenched, and then aged at 175 °C for 8 h; finally, the compact is finished.

[0061] The properties of the six-system aluminum alloy materials obtained in Examples 1-3 and Comparative Examples 1-3 are tested according to the test specifications of national and industry standards. The corresponding samples are cut from the six-system aluminum alloy materials obtained in Examples 1-3 and Comparative Examples 1-3 using a wire cut electrical discharge machine. The tensile samples are processed into cylindrical samples with a gauge length of 30 mm and a diameter of 6 mm, the hardness samples are processed into 10 mm x 10 mm x 8 mm cubes, and the metallographic samples are processed into 15 mm diameter and 5 mm thick discs. All samples are ground with 180, 400, 800, and 1200 grit sandpaper in order from coarse to fine, then mechanically polished with diamond polishing agent, and finally etched with Keller reagent at room temperature for 10 s for microstructure observation.

[0062] Tensile testing is performed on a microcomputer-controlled electronic universal testing machine, with a 25 mm gauge extensometer installed and a loading rate set to 1 mm / min. The load-displacement curve is continuously recorded until the sample breaks. Stress-strain data is simultaneously collected during the test, and the tensile strength, yield strength, and elongation are determined from the engineering stress-strain curve, with the yield strength determined using the 0.2% offset method. Each sample is tested 5 times, and the highest and lowest values are discarded, with the average of the remaining 3 test results taken as the final data.

[0063] The hardness test uses a Vickers hardness tester, selects a right tetrahedral pyramid diamond indenter, the test force is set to 490.3N, and the holding time is strictly controlled to 15s. The indentation test is performed at the center area and four symmetric points 2mm away from the center of the polished surface of each sample, ensuring that the indentation spacing is greater than 3 times the length of the indentation diagonal. The length of two diagonals of each indentation is measured and the average value is obtained. The Vickers hardness value is calculated by looking up the table, and the arithmetic average of the hardness results of 5 test points is taken as the hardness result of the sample.

[0064] Microstructure analysis uses a scanning electron microscope equipped with an energy spectrometer, with an acceleration voltage set to 20kV and a working distance adjusted to 10mm. The etched metallographic sample is treated with carbon spraying to enhance conductivity, and 5 random fields are collected under 1000x magnification to obtain backscattered electron images. Image analysis software is used to process the collected images and identify grain boundaries. The intercept method is used to measure the grain size, and at least 20 grains are counted in each field. The average value of all measurement results is finally calculated as the average grain size of the sample. All tests are performed in an environment with a temperature of 23±2℃ and a relative humidity of 50±5%, and all samples are allowed to stand in the test environment for 24h to achieve temperature equilibrium before testing.

[0065] The performance test data is shown in Table 1.

[0066] Table 1 Performance test results

[0067] Test item Example 1 Example 2 Example 3 Comparative Example 1 Comparative Example 2 Comparative Example 3 Tensile strength (MPa) 320 305 315 260 250 230 Yield strength (MPa) 280 265 275 220 210 190 Elongation (%) 12.5 11.8 12.2 8.5 7.8 6.5 Vickers hardness (HV) 110 105 108 90 85 75 Average grain size (μm) 8.5 9.2 8.8 15.6 14.3 18.5

[0068] The test results in Table 1 clearly show that Examples 1-3 effectively solve the key technical problems of coarse grains and insufficient mechanical properties of traditional six-series aluminum alloys in the metal injection molding process by synergistically using nano yttrium zirconium nitride composite grain refiner and indium gallium silicon composite oxide sintering aid. Example 1 exhibits the best overall performance, with a tensile strength of 320 MPa, a yield strength of 280 MPa, an elongation of 12.5%, a Vickers hardness of 110 HV, and an average grain size of 8.5 μm. Compared with the sample of Comparative Example 3 without any modifier, the tensile strength is increased by 39.1%, the yield strength is increased by 47.4%, the elongation is increased by 92.3%, the hardness is increased by 46.7%, and the grain size is refined by 54.1%. Comparative Example 1 only uses sintering aid without grain refiner, with an average grain size of 15.6 μm, and the mechanical properties are significantly lower than those of Example 1, which proves the key role of nano yttrium zirconium nitride composite grain refiner in inhibiting grain growth and promoting fine-grain strengthening. Comparative Example 2 only uses grain refiner without sintering aid, and the insufficient densification results in a tensile strength of only 250 MPa and a hardness of 85 HV, indicating that the indium gallium silicon composite oxide sintering aid effectively promotes material densification and grain boundary strengthening by improving the sintering kinetics process. The excellent performance of the three examples benefits from the synergistic mechanism of the two modifiers: nano yttrium zirconium nitride as a heterogeneous nucleation core effectively refines the grains, while indium gallium silicon composite oxide forms a liquid phase sintering promoter at the grain boundary to promote mass transfer, and the two work together to achieve multiple strengthening effects of fine-grain strengthening, solid solution strengthening and precipitation strengthening, successfully solving the technical problems of excessive grain growth and insufficient sintering densification of six-series aluminum alloys in the injection molding process due to the sintering temperature close to the solidus.

Claims

1. A method for preparing a six-series aluminum alloy material, characterized in that the steps include... include: S1. Aluminum powder, magnesium powder, silicon powder, copper powder, manganese powder, chromium powder, zinc powder, iron powder, titanium powder, as well as nano-yttrium zirconium nitride composite grain refiner and indium gallium silicon composite oxide sintering aid are placed in a mixer and mixed under argon protection to obtain mixed metal powder; the mixed metal powder and binder are mixed in an internal mixer at 150-170℃ to obtain feed; S2. The feed material is injected into a precision mold and injection molded at 74-76℃ to obtain a green body. The green body is placed in an oxalic acid catalytic degreasing furnace and degreased in an oxalic acid atmosphere at 115-125℃ to obtain a blank. The blank is heated to 450-550℃ in a hydrogen atmosphere and held at that temperature. It is then transferred to a high-temperature sintering furnace and sintered at 625-635℃ in a nitrogen protective atmosphere. After sintering, it is solution treated at 534-536℃, then water quenched, and then aged at 174-176℃. Finally, it is finished. The preparation method of the nano-yttrium zirconium nitride composite grain refiner includes: A1. Dissolving yttrium nitrate and zirconium oxynitrate in deionized water to obtain a salt solution; adding the salt solution dropwise to a precipitant containing ammonia under stirring conditions, maintaining the pH of the solution at 9-10, to obtain a yttrium zirconium hydroxide coprecipitate; vacuum filtering the yttrium zirconium hydroxide coprecipitate and washing it with deionized water to obtain a clean precipitate; drying the clean precipitate in a vacuum drying oven at 78-82℃ to obtain a yttrium zirconium hydroxide precursor; A2. Transferring the yttrium zirconium hydroxide precursor to a tube furnace, heating it to 795-805℃ under an ammonia atmosphere, holding it at that temperature, and naturally cooling it to room temperature to obtain nano-yttrium zirconium nitride composite powder; ball milling the nano-yttrium zirconium nitride composite powder under argon protection; The preparation method of the indium gallium silicon composite oxide sintering aid includes: B1, dissolving indium nitrate, gallium nitrate and tetraethyl orthosilicate in anhydrous ethanol, adding acetylacetone, and stirring under reflux in a water bath at 58-62℃ to obtain a complex solution; adding polyethylene glycol to the complex solution and continuing to stir at 58-62℃ to obtain a reaction solution; B2, transferring the reaction solution to a high-pressure reactor and solvating it at 118-122℃, and obtaining a colloidal solution after cooling; concentrating the colloidal solution in a rotary evaporator at 58-62℃, then adding n-hexane, and obtaining a gel product by centrifugation; drying the gel product in a vacuum drying oven at 38-42℃, grinding it to obtain a ground powder; and then calcining the ground powder at 400-500℃ in an air atmosphere.

2. The method for preparing the six-series aluminum alloy material according to claim 1, characterized in that, In step S1, the mixing time under argon protection is 4-6 hours.

3. The method for preparing the six-series aluminum alloy material according to claim 1, characterized in that, In step S2, the temperature is raised to 625-635℃ and the sintering time is 2-4 hours.

4. The method for preparing the six-series aluminum alloy material according to claim 1, characterized in that, In step A1, the drying time in a vacuum drying oven at 78-82℃ is 12-14 hours.

5. The method for preparing the six-series aluminum alloy material according to claim 1, characterized in that, In step A2, the temperature is heated to 795-805℃ and held for 2-4 hours.

6. The method for preparing the six-series aluminum alloy material according to claim 1, characterized in that, In step B1, the stirring and reflux time in a 58-62℃ water bath is 1-2 hours.

7. The method for preparing the six-series aluminum alloy material according to claim 1, characterized in that, In step B2, the solvent heat treatment at 118-122℃ takes 6-8 hours.

8. A six-series aluminum alloy material prepared by the method according to any one of claims 1-7, characterized in that, The raw materials include the following parts by weight: 85-92 parts aluminum powder; 0.6-1.2 parts magnesium powder; 0.5-1.2 parts silicon powder; 0.1-0.5 parts copper powder; 0.05-0.3 parts manganese powder; 0.05-0.2 parts chromium powder; 0.05-0.15 parts zinc powder; 0.1-0.2 parts iron powder; 0.05-0.1 parts titanium powder; 0.1-0.5 parts nano-yttrium zirconium nitride composite grain refiner; 0.2-0.8 parts indium gallium silicon composite oxide sintering aid; and 8-15 parts binder.