In-situ synthesis process for preparing light-weight high-strength aluminum matrix composite

Abstract

The application discloses a kind of in-situ synthesis preparation processes of lightweight high-strength aluminum matrix composite.The process uses the mixture containing zinc powder, potassium fluozirconate, magnesium powder and the rest is titanium powder and boron powder (mass ratio), and is pressed into a preform block with a relative density of 0.5-0.7;The preform block is put into the aluminum melt, and the endogenous heat generated by the reduction exothermic reaction of magnesium powder and potassium fluozirconate is combined with the pore limited liquid phase formed by the melting of zinc powder to improve the solid phase diffusion kinetics;This method reduces the in-situ synthesis temperature to 800-900 DEG C, reduces the high-temperature gettering oxidation, and avoids the generation of a large amount of cryolite salt slag by-product;After the reaction is completed, zinc and magnesium are dissolved into the aluminum matrix to realize the synchronization of matrix alloying and dispersion distribution of reinforcing phase, and improve the mechanical properties of the composite material.

Description

Technical Field

[0001] This invention relates to the field of metal matrix composite material preparation technology for aerospace structural components, specifically to an in-situ synthesis preparation process for a lightweight, high-strength aluminum matrix composite material, which falls under the category of novel aerospace aluminum alloy material preparation technology. Background Technology

[0002] Particle-reinforced aluminum matrix composites are widely used in lightweight structural manufacturing due to their high specific strength, high specific stiffness, and excellent wear resistance. They are particularly prevalent in the manufacture of load-bearing structural components and heat-resistant parts for aircraft. As an important branch of new aerospace aluminum alloy materials, their lightweight and high-strength characteristics are crucial for reducing structural weight and improving flight performance. Among numerous preparation methods, in-situ synthesis technology has become the main process route for preparing high-performance aluminum matrix composites because of the small size, clean surface, and good interfacial bonding of the resulting reinforcing phase particles.

[0003] Currently, the mixed salt reaction method is commonly used in the industrial synthesis of titanium boride particle-reinforced aluminum matrix composites. This process involves directly adding potassium fluorotitanate and potassium fluoroborate powders to high-temperature molten aluminum, relying on the aluminum melt to reduce the aforementioned halide salts, generating free titanium and boron atoms, which then undergo a combination reaction to form titanium boride particles. This reaction system requires a high activation temperature, typically needing to raise and maintain the operating temperature of the molten aluminum above 850°C. Under this high-temperature environment, the molten aluminum undergoes severe hydrogen absorption and oxidation, leading to porosity defects within the final solidified composite casting, thus reducing the material's macroscopic density and load-bearing capacity. During the reaction, the reduction of halide salts generates a large amount of cryolite-type salt slag byproducts, accompanied by the release of toxic fluoride gases. The large amount of salt slag not only increases the workload of melt refining and slag removal processes, but the residue inclusions also deteriorate material properties, while the volatile gases cause severe corrosion to smelting equipment, posing a potential environmental pollution hazard.

[0004] To avoid the aforementioned salt slag contamination problem, some existing technologies attempt to directly add elemental pure titanium powder and pure boron powder to the aluminum melt for in-situ reaction. However, at the melting temperature of conventional aluminum alloys (approximately...),... At certain temperatures, liquid aluminum exhibits extremely poor wettability towards solid titanium and boron powders, resulting in a high interfacial diffusion barrier for solid-phase atoms. Without the use of large amounts of covering agents or diluents, directly added titanium and boron powders at conventional aluminum melt temperatures (approximately...) The in-situ synthesis reaction of titanium and boron is difficult to initiate and complete spontaneously under certain conditions, and usually requires extremely high local excitation temperatures to trigger the chemical reaction between titanium and boron. Therefore, within the conventional metallurgical temperature range, the direct addition of elemental powders is difficult to achieve a sufficient reaction, resulting in a large number of unreacted coarse solid particles remaining in the matrix as inclusions, which fails to achieve the purpose of material strengthening. Summary of the Invention

[0005] To address the problems mentioned in the background section and meet the comprehensive requirements of aerospace structural components for lightweight, high-strength, low-porosity, and high-dimensional stability of novel aerospace aluminum alloy materials, the technical solution of this invention is as follows:

[0006] A first aspect of the present invention provides a preform of a composition for in-situ synthesis of lightweight, high-strength aluminum-based composite materials, comprising, by weight percentage, the following components: zinc powder Potassium fluorozirconate powder Magnesium powder The remainder consists of titanium powder and boron powder, and the mass ratio of the titanium powder to the boron powder is [missing information]. .

[0007] Preferably, the preferred proportions of the components in the preform of the composition, by mass percentage, are: zinc powder Potassium fluorozirconate powder Magnesium powder Titanium powder Boron powder .

[0008] Preferably, the specific parameters of each component raw material are as follows: the median diameter of the zinc powder is between Between, purity ≥ The median diameter of the magnesium powder is between Between, purity ≥ The median diameter of the potassium fluorozirconate powder is between Between, purity ≥ The median diameter of the titanium powder is between Between, purity ≥ The median diameter of the boron powder is between Between, purity ≥ .

[0009] Preferably, the actual relative density of the preformed composition is equal to the theoretical dense density. .

[0010] A second aspect of the present invention provides an in-situ synthesis process for a lightweight, high-strength aluminum-based composite material, using the preform of the composition described in the first aspect, comprising the following steps:

[0011] Step S1, Substrate Melting: The aluminum substrate is heated to completely melt, and then the temperature of the molten aluminum is adjusted and kept constant at a certain level. ;

[0012] Step S2, Pre-formed block addition and isothermal reaction: The pre-formed block of the composition is pressed into the above-mentioned aluminum melt for isothermal reaction;

[0013] Step S3, mechanical stirring and homogenization: After the isothermal reaction period, the melt is mechanically stirred;

[0014] Step S4, Degassing, Refining and Casting: The stirred melt is degassed, refined and slag removed, and then poured into a mold to cool and solidify, resulting in a lightweight, high-strength aluminum-based composite material.

[0015] Preferably, before step S2, the specific preparation method of the preform of the composition includes: weighing the powders of each component under an argon protective atmosphere, loading them into a mixing tank and mixing them evenly; filling the mixed powder into a mold, and applying it at room temperature. Unidirectional load and pressure holding Depressurize and demold to obtain precast blocks of the composition with the required density.

[0016] Preferably, the specific process parameters for step S2 are: the preform of the composition is vertically pressed into the molten aluminum, and the immersion depth is equal to the total depth of the molten aluminum. ;Keep constant temperature During this isothermal reaction stage, the mechanical stirring equipment is turned off to maintain the macroscopic stillness of the melt. The mass ratio of the precast composite block to the aluminum matrix is ​​set according to the design composition requirements of the final alloy, and is usually controlled at [specific ratio]. between.

[0017] Preferably, step S3 is implemented as follows: a titanium alloy stirring paddle coated with a boron nitride protective layer is inserted into the melt for stirring, and the stirring paddle speed is set to... Continue stirring .

[0018] Preferably, the specific process parameters for degassing and refining in step S4 are as follows: a rotary jet degasser is used for processing, with the graphite rotor penetrating deep into the bottom of the melt. At this location, the rotation speed is set to At the same time, the incoming flow is High-purity argon gas, continuously degassing .

[0019] Preferably, during the melting process in step S1, a flow rate of [flow rate missing] is continuously introduced at the top of the crucible. Argon gas; during the casting process in step S4, the refined composite material melt is smoothly poured to the preheated temperature. In the metal mold.

[0020] In this process, the zirconium element in potassium fluorozirconate is dissolved in trace amounts in the aluminum matrix, which plays a role in grain refinement. The potassium element volatilizes in gaseous form at high temperature, and the fluorine element combines with magnesium or aluminum to form a fluoride slag phase, which is effectively removed during the degassing, refining and slag removal process.

[0021] The present invention, by adopting the above technical solution, can bring the following beneficial effects:

[0022] 1. This invention utilizes the exothermic reduction reaction of elemental magnesium powder and potassium fluorozirconate powder in the aluminum melt to generate internal heat by adding elemental magnesium powder and potassium fluorozirconate powder to the preform. Combined with the localized liquid phase medium formed by the melting of low-melting-point zinc powder, the overall operating temperature of the in-situ synthesis reaction is reduced from the traditional... The above has been reduced to The low-temperature synthesis process effectively suppressed severe gas absorption and oxidation of the aluminum alloy melt under high-temperature conditions, reduced the internal porosity of the composite casting, and improved the macroscopic density of the material, meeting the stringent requirements of new aerospace aluminum alloy materials for internal metallurgical quality and high airtightness.

[0023] 2. This invention uses pure titanium powder and pure boron powder as the main reactants for reinforcing phases, and only uses a mass fraction of [missing information]. Potassium fluorozirconate, acting as a heat source initiator, provides localized high temperatures within the preform through its exothermic reaction with magnesium powder. Simultaneously, its decomposition products help break down the oxide films on the surfaces of titanium and boron powders, promoting in-situ synthesis and thus altering the traditional synthesis pathway that relies entirely on the reduction of large amounts of halogen salts. This formulation significantly reduces the generation of fluorine-containing byproducts and salt slag during the reaction, substantially lowers the emission of toxic fluoride gases and cryolite-type salt slag, simplifies melt refining and slag removal processes, reduces equipment corrosion, and improves the cleanliness of the production environment.

[0024] 3. This invention selects zinc from the target alloy composition as a liquid-phase confinement carrier inside the preform and magnesium as a pre-heat trigger. After the reaction to synthesize titanium boride particles in situ is completed, zinc and unconsumed magnesium directly diffuse and dissolve into the aluminum matrix. This compositional design ensures that all intermediate substances participating in the reaction process are transformed into effective alloying elements that play a role in solid solution and precipitation strengthening in the final aluminum matrix. The system does not introduce a large amount of salt-like impurities that require subsequent stripping. Reaction byproducts can be effectively removed through degassing, refining, and slag removal processes. This achieves simultaneous completion of matrix alloying and the dispersed distribution of reinforcing phases. The resulting material has both low density and high specific strength, making it suitable for the preparation of novel aerospace aluminum alloy materials for aerospace structural components. Attached Figure Description

[0025] Figure 1 A schematic flowchart of an in-situ synthesis process for aluminum-based composite materials provided by the present invention;

[0026] Figure 2 This is a comparison curve of the time-domain temperature evolution of the melt inside and around the precast block in Test Example 1 of the present invention;

[0027] Figure 3This is a bar chart comparing the in-situ reaction conversion rates of each group in Test Example 2 of this invention;

[0028] Figure 4 This is a room temperature tensile stress-strain curve diagram of the key group in Test Example 3 of the present invention. Detailed Implementation

[0029] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. The novel in-situ synthesis and preparation process of aerospace aluminum alloy materials provided in the following embodiments verifies the application requirements of lightweight and high-strength aluminum-based composite materials for aerospace structural components. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0030] Please see the appendix Figure 1-4 This invention provides an in-situ synthesis process for lightweight, high-strength aluminum-based composite materials.

[0031] The main raw materials and reagents used in the following examples and comparative examples have the following sources and specifications: Reagents not specifically mentioned are all commercially available analytical grade or higher grade products;

[0032] The aluminum matrix uses commercial 1060 pure aluminum ingots with a pure aluminum mass fraction greater than or equal to 99.6% and CAS number 7429-90-5. This matrix selection takes into account the requirements of aerospace aluminum alloy materials for impurity control and process adaptability.

[0033] The zinc powder is spherical atomized pure zinc powder, with a physical form of spherical particles, a purity greater than or equal to 99.9%, a median diameter (D50) between 10μm and 30μm, and a CAS number of 7440-66-6.

[0034] The magnesium powder is spherical atomized pure magnesium powder, with a physical form of spherical particles, a purity greater than or equal to 99.5%, a median diameter (D50) between 20μm and 50μm, and a CAS number of 7439-95-4.

[0035] Potassium fluorozirconate is a commercially available inorganic salt with the chemical formula: The physical form is a crystalline powder with a purity greater than or equal to 99.0%, a median diameter (D50) between 5 μm and 15 μm, and the CAS number is 16923-95-8.

[0036] The titanium powder is made from sponge titanium crushed powder, which is in the form of irregular crushed particles with a purity greater than or equal to 99.5% and a median diameter (D50) between 10μm and 40μm. The CAS number is 7440-32-6.

[0037] The boron powder used is amorphous boron powder, which is amorphous powder in physical form, with a purity greater than or equal to 95.0%, a median diameter (D50) between 1μm and 5μm, and CAS number 7440-42-8.

[0038] Argon gas is commercially available in high-purity specifications, with a purity greater than or equal to 99.99%, and CAS number 7440-37-1.

[0039] Preparation Example

[0040] Preparation Example 1:

[0041] This preparation example provides a preform for in-situ synthesis of aluminum-based composite materials, comprising the following steps:

[0042] Step S1: Weigh the powder in a glove box under an argon protective atmosphere. The mass percentage composition of each component is as follows: zinc powder 20.0%, potassium fluorozirconate 2.0%, magnesium powder 1.0%, titanium powder 53.09%, and boron powder 23.91% (where the mass ratio of titanium powder to boron powder is...). );

[0043] Step S2: The weighed powder is loaded into a stainless steel V-shaped mixing tank. Argon gas with a purity greater than or equal to 99.99% is filled into the tank to 0.12 MPa. The rotation speed is set to 30 r / min and the mixing time is 4 h. After the mixing is completed, the powder is passed through a 100-mesh stainless steel sieve to obtain mixed powder.

[0044] Step S3: Calculate the theoretical dense density of the mixed powder based on the theoretical density of each pure substance and the mixing rule. Fill the mixed powder into a hard alloy steel mold with an inner diameter of 50 mm. Apply a unidirectional load of 120 MPa at room temperature and hold for 60 seconds. Release the pressure and demold. By controlling the load parameters, control the actual relative density of the precast block to 70.0% of the theoretical density.

[0045] Preparation Example 2:

[0046] This preparation example provides a preform for in-situ synthesis of aluminum-based composite materials, comprising the following steps:

[0047] Step S1: Weigh the powder in a glove box under an argon protective atmosphere. The mass percentage composition of each component is as follows: zinc powder 25.0%, potassium fluorozirconate 3.5%, magnesium powder 2.0%, titanium powder 47.92%, and boron powder 21.58% (where the mass ratio of titanium powder to boron powder is...). );

[0048] Step S2: The weighed powder is loaded into a stainless steel V-shaped mixing tank. Argon gas with a purity greater than or equal to 99.99% is filled into the tank to 0.12 MPa. The rotation speed is set to 40 r / min and the mixing time is 3 h. After the mixing is completed, the powder is passed through a 100-mesh stainless steel sieve to obtain mixed powder.

[0049] Step S3: Calculate the theoretical dense density of the mixed powder based on the theoretical density of each pure substance and the mixing rule. Fill the mixed powder into a hard alloy steel mold with an inner diameter of 50 mm. Apply a unidirectional load of 150 MPa at room temperature and hold for 45 s. Release the pressure and demold. By controlling the load parameters, control the actual relative density of the precast block to 72.5% of the theoretical density.

[0050] Preparation Example 3:

[0051] This preparation example provides a preform for in-situ synthesis of aluminum-based composite materials, comprising the following steps:

[0052] Step S1: Weigh the powder in a glove box under an argon protective atmosphere. The mass percentage composition of each component is as follows: zinc powder 30.0%, potassium fluorozirconate 5.0%, magnesium powder 3.0%, titanium powder 42.75%, and boron powder 19.25% (where the mass ratio of titanium powder to boron powder is...). );

[0053] Step S2: The weighed powder is loaded into a stainless steel V-shaped mixing tank. Argon gas with a purity greater than or equal to 99.99% is filled into the tank to 0.12 MPa. The rotation speed is set to 50 r / min and the mixing time is 2 h. After the mixing is completed, the powder is passed through a 100-mesh stainless steel sieve to obtain mixed powder.

[0054] Step S3: Calculate the theoretical dense density of the mixed powder based on the theoretical density of each pure substance and the mixing rule. Fill the mixed powder into a hard alloy steel mold with an inner diameter of 50 mm. Apply a unidirectional load of 180 MPa at room temperature and hold for 30 seconds. Release the pressure and demold. By controlling the load parameters, control the actual relative density of the precast block to 75.0% of the theoretical density.

[0055] Example

[0056] Example 1:

[0057] This embodiment provides an in-situ synthesis process for aluminum-based composite materials based on internal cascade reactions and transient liquid-phase confinement, including the following steps:

[0058] Step S1, matrix melting: 1060 pure aluminum ingots are placed into a graphite crucible in a medium-frequency induction melting furnace, and the temperature is raised to completely melt the pure aluminum ingots. Then the temperature of the aluminum melt is adjusted and kept constant at 700°C. During the melting process, argon gas with a flow rate of 5L / min is continuously introduced into the top of the crucible. The mass ratio of the preformed composition block to the aluminum matrix is ​​1:10.

[0059] Step S2, Pre-block addition and isothermal reaction: The pre-block obtained in Preparation Example 1 is placed in a graphite bell jar tool and vertically pressed into the aluminum melt at 700°C. The immersion depth is 1 / 2 of the total depth of the melt. The temperature is kept constant at 700°C for 15 minutes. During this stage, the mechanical stirring equipment is turned off to keep the melt macroscopically still.

[0060] Step S3, mechanical stirring and homogenization: After the isothermal reaction period, remove the bell jar tool and insert the titanium alloy stirring paddle with a boron nitride protective layer on its surface into the melt. Set the stirring paddle speed to 200 r / min and continue stirring for 3 min.

[0061] Step S4, Degassing and Refining and Casting: Degassing and refining are carried out using a rotary jet degasser. The graphite rotor is inserted 3cm into the bottom of the melt, and the rotation speed is set to 300r / min. At the same time, high-purity argon gas with a flow rate of 1.5L / min is introduced and degassing is continued for 10min. After degassing, the melt is allowed to stand for 5min and the surface residue is scraped off using a steel slag scraper. The refined composite material melt is poured smoothly into a metal mold with a preheated temperature of 200℃ and allowed to cool and solidify naturally in room temperature air to obtain aluminum-based composite material.

[0062] Example 2:

[0063] This embodiment provides an in-situ synthesis process for aluminum-based composite materials based on internal cascade reactions and transient liquid-phase confinement, including the following steps:

[0064] Step S1, matrix melting: 1060 pure aluminum ingots are placed into a graphite crucible in a medium-frequency induction melting furnace, and the temperature is raised to completely melt the pure aluminum ingots. Then the temperature of the aluminum melt is adjusted and kept constant at 710°C. During the melting process, argon gas with a flow rate of 8L / min is continuously introduced into the top of the crucible. The mass ratio of the preformed composition block to the aluminum matrix is ​​1:8.

[0065] Step S2, Pre-block addition and isothermal reaction: The pre-block obtained in Preparation Example 2 is placed in a graphite bell jar tool and vertically pressed into the aluminum melt at 710°C. The immersion depth is between 1 / 2 and 2 / 3 of the total depth of the melt. The temperature is kept constant at 710°C for 18 minutes. During this stage, the mechanical stirring equipment is turned off to keep the melt macroscopically still.

[0066] Step S3, mechanical stirring and homogenization: After the isothermal reaction period, remove the bell jar tool and insert the titanium alloy stirring paddle with a boron nitride protective layer on its surface into the melt. Set the stirring paddle speed to 250 r / min and continue stirring for 4 min.

[0067] Step S4, Degassing and Refining and Casting: Degassing and refining are carried out using a rotary jet degasser. The graphite rotor is inserted 4cm into the bottom of the melt, and the rotation speed is set to 380r / min. At the same time, high-purity argon gas with a flow rate of 2.0L / min is introduced and degassing is continued for 12min. After degassing, the melt is allowed to stand for 8min and the surface residue is scraped off with a steel slag scraper. The refined composite material melt is poured smoothly into a metal mold with a preheated temperature of 225°C and allowed to cool and solidify naturally in room temperature air to obtain aluminum-based composite material.

[0068] Example 3:

[0069] This embodiment provides an in-situ synthesis process for aluminum-based composite materials based on internal cascade reactions and transient liquid-phase confinement, including the following steps:

[0070] Step S1, matrix melting: 1060 pure aluminum ingots are placed into a graphite crucible in a medium-frequency induction melting furnace, and the temperature is raised to completely melt the pure aluminum ingots. Then the temperature of the aluminum melt is adjusted and kept constant at 720°C. During the melting process, argon gas with a flow rate of 10L / min is continuously introduced into the top of the crucible. The mass ratio of the preformed composition block to the aluminum matrix is ​​1:12.

[0071] Step S2, Pre-block addition and isothermal reaction: The pre-block obtained in Preparation Example 3 is placed in a graphite bell jar tool and vertically pressed into the aluminum melt at 720°C. The immersion depth is 2 / 3 of the total depth of the melt. The temperature is kept constant at 720°C for 20 minutes. During this stage, the mechanical stirring equipment is turned off to keep the melt macroscopically still.

[0072] Step S3, mechanical stirring and homogenization: After the isothermal reaction period, remove the bell jar tool and insert the titanium alloy stirring paddle with a boron nitride protective layer on its surface into the melt. Set the stirring paddle speed to 300 r / min and continue stirring for 5 min.

[0073] Step S4, Degassing and Refining and Casting: Degassing and refining are carried out using a rotary jet degasser. The graphite rotor is inserted 5cm into the bottom of the melt, and the rotation speed is set to 450r / min. At the same time, high-purity argon gas with a flow rate of 3.0L / min is introduced and degassing is continued for 15min. After degassing, the melt is allowed to stand for 10min and the surface residue is scraped off using a steel slag scraper. The refined composite material melt is poured smoothly into a metal mold with a preheated temperature of 250℃ and allowed to cool and solidify naturally in room temperature air to obtain aluminum-based composite material.

[0074] Comparative Example

[0075] Comparative Example 1:

[0076] Compared to Example 2, the difference is that no magnesium powder is added to the mixed powder component of the preform; the original magnesium powder is composed of equal proportions of titanium powder and boron powder (the mass ratio of the two is maintained at 1%). () is replaced, and the rest are the same.

[0077] Comparative Example 2:

[0078] Compared with Example 2, the difference is that in the pressing and molding step of the preform, the applied unidirectional load is significantly increased, and the actual relative density of the preform is controlled to 95.0% of the theoretical density, while the rest are the same.

[0079] Comparative Example 3:

[0080] Compared with Example 2, the difference is that no zinc powder is added to the mixed powder component of the preform, and the original zinc powder mass percentage is replaced by pure aluminum powder, while the rest are the same.

[0081] Comparative Example 4:

[0082] Compared with Example 2, the difference is that the pressing and molding step of the preformed block is omitted, and the mixture of zinc powder, potassium fluorozirconate, magnesium powder, titanium powder and boron powder of the same mass and ratio as in Example 2 is directly added to the aluminum melt in bulk powder form. All other aspects are the same.

[0083] Comparative Example 5:

[0084] Compared with Example 2, the difference is that the pre-formed block system of the present invention is not used. Instead, the traditional mixed salt method is adopted. Commercially available potassium fluorotitanate and potassium fluoroborate are directly mixed in the stoichiometric ratio for the formation of titanium boride and then added to the aluminum melt. The temperature of the aluminum matrix melting and isothermal reaction is increased and kept constant at 850°C. All other aspects are the same.

[0085] The following provides detailed experimental descriptions, test data, plotting suggestions, and conclusions for each test case.

[0086] Test Example 1: Time-Domain Temperature Gradient Test

[0087] This test is used to verify the exothermic evolution process of the preform inside the aluminum melt.

[0088] Experimental steps: Connect two K-type thermocouples to a dual-channel temperature data acquisition instrument. Pre-embed the first thermocouple probe in the center of the mixed powder and press it into shape to obtain a preform. After the preform is put into the aluminum melt, insert the second thermocouple probe into the aluminum melt at a distance of 50mm from the surface of the preform. Set the sampling frequency to 1Hz and record the temperature data within 20 minutes after feeding.

[0089] Table 1. Time-domain temperature variation data (captured at specific time points)

[0090]

[0091] Experimental conclusions: In Example 2, the internal temperature of the preform rose within 90 to 150 seconds after feeding, reaching a peak of 814.2℃, while the temperature of the surrounding molten aluminum fluctuated around 710℃. In Comparative Example 1, which did not add magnesium powder, the internal temperature of the preform gradually increased over time and tended to be consistent with the temperature of the molten aluminum, without the generation of a temperature peak. The elemental magnesium contained in the example reacted with potassium fluorozirconate in a reduction reaction and released heat. This heat accumulated inside the pores of the preform, causing the local temperature to exceed the ambient temperature of the molten aluminum, reaching the trigger temperature required for the self-propagating reaction of titanium and boron. This result indicates that the lead reaction of magnesium with potassium fluorozirconate can act as a heat source to initiate in-situ synthesis inside the preform.

[0092] Test Example 2: In-situ reaction conversion rate determination

[0093] This test is used to quantitatively evaluate the degree of reaction completion in the synthesis of titanium boride from titanium powder and boron powder in various reaction systems.

[0094] Experimental Procedure: A 15g sample was taken from the center of the cooled ingot and placed in a 10% sodium hydroxide aqueous solution. The solution was heated in an 80℃ water bath. After the aluminum matrix and alloying elements dissolved, the sample was vacuum filtered using a 0.22μm pore size filter membrane. The filter residue was washed three times with deionized water and anhydrous ethanol, respectively. After drying, the filter residue was placed in a polytetrafluoroethylene beaker and digested with a mixture of hydrofluoric acid and nitric acid. After the digestion solution was brought to a final volume, the mass concentrations of titanium and boron were determined using inductively coupled plasma atomic emission spectrometry (ICP-AES). The residual amounts of free titanium and boron were calculated, and the reaction conversion rate of titanium was obtained.

[0095] Table 2. Data on the Conversion Rate of Titanium in the Reaction System

[0096]

[0097] Experimental conclusions: The titanium conversion rates in Examples 1 to 3 were all above 96% at reaction temperatures ranging from 700℃ to 720℃. Comparative Example 5, smelted at 850℃ using conventional high-temperature methods, achieved a conversion rate of 95.20%. Comparative Example 1 (without magnesium powder), Comparative Example 3 (without zinc powder), and Comparative Example 4 (with direct bulk powder addition) achieved conversion rates of 21.78%, 11.77%, and 7.84%, respectively. In Comparative Example 2, the relative density of the preform increased to 95.0%, resulting in a conversion rate of 43.61%. The comparison shows that at lower aluminum melt temperatures, controlling the porosity within the preform and incorporating low-melting-point zinc allows the zinc to melt and form a liquid phase medium within the pores, altering the solid-phase diffusion path between titanium and boron powders, thereby improving the synthesis conversion rate at low temperatures.

[0098] Test Example 3: Comprehensive Test of Macroscopic Density and Mechanical Properties

[0099] This test is used to evaluate the macroscopic physical state and engineering mechanical properties of the final composite material.

[0100] Experimental Procedure: Measure the mass of each group of casting samples in air and the apparent mass in pure water, and calculate the actual density and porosity. Machine cylindrical tensile specimens with a gauge length diameter of 5.0 mm along the longitudinal direction of the ingot; conduct tensile tests using a universal testing machine at room temperature, with a loading rate set to 1.0 mm / min; record the strain using an extensometer; and determine the tensile strength, yield strength, and elongation after fracture. Test three specimens for each group and take the average value.

[0101] Table 3. Comprehensive Data of Macroscopic Physical Parameters and Room Temperature Tensile Mechanical Properties

[0102]

[0103] Experimental conclusions: The porosity of Examples 1 to 3 remained between 1.08% and 1.21%, with the tensile strength of Example 2 being 512.4 MPa; Comparative Example 5, using an 850℃ process, had a porosity of 5.67% and a tensile strength of 345.2 MPa; the tensile strength of Comparative Examples 1 to 4 was all below 300 MPa; the synthesis reaction in the example systems was completed at 700℃ to 720℃, reducing the absorption of gas by the aluminum liquid at high temperatures, resulting in a lower porosity than the 850℃ process; after the synthesis reaction, the reaction carrier zinc and the trigger magnesium dissolved into the aluminum matrix, producing alloy solid solution and precipitation strengthening effects, combined with the dispersion strengthening caused by the in-situ generated titanium boride particles, improving the tensile properties of the material; in Comparative Examples 1 to 4, due to incomplete internal synthesis reactions, unreacted free titanium powder and boron powder remained in the aluminum matrix, causing macroscopic defects and stress concentration, leading to a decrease in the overall strength and elongation of the material.

Claims

1. A preform of a composition for in-situ synthesis of lightweight, high-strength aluminum-based composite materials, characterized in that, By weight percentage, it includes the following components: zinc powder Potassium fluorozirconate powder Magnesium powder The remainder consists of titanium powder and boron powder, and the mass ratio of the titanium powder to the boron powder is [missing information]. .

2. The preform of the composition for in-situ synthesis of lightweight high-strength aluminum-based composite materials according to claim 1, characterized in that, The preferred proportions of each component by mass percentage are as follows: zinc powder Potassium fluorozirconate powder Magnesium powder Titanium powder Boron powder .

3. The preform of the composition for in-situ synthesis of lightweight high-strength aluminum-based composite materials according to claim 1, characterized in that, The median diameter of the zinc powder is between Between, purity ≥ The median diameter of the magnesium powder is between Between, purity ≥ The median diameter of the potassium fluorozirconate powder is between Between, purity ≥ The median diameter of the titanium powder is between Between, purity ≥ The median diameter of the boron powder is between Between, purity ≥ .

4. The preform of the composition for in-situ synthesis of lightweight high-strength aluminum-based composite materials according to claim 1, characterized in that, The specific performance parameters of the precast block of the composition are: it contains interconnected pores, and the actual relative density of the precast block of the composition is controlled to be the theoretical dense density. .

5. An in-situ synthesis process for a lightweight, high-strength aluminum-based composite material, characterized in that, The preformed block using the composition according to any one of claims 1-4 includes the following steps: Step S1, Base Melting: The temperature is raised to completely melt the pure aluminum ingot, and then the temperature of the molten aluminum is adjusted and kept constant at a certain level. ; Step S2, Pre-formed block addition and isothermal reaction: The pre-formed block of the composition is pressed into the aluminum melt above for isothermal reaction; Step S3, mechanical stirring and homogenization: After the isothermal reaction period, the melt is mechanically stirred; Step S4, Degassing, Refining and Casting: The stirred melt is degassed, refined and slag removed, and then poured into a mold to cool and solidify, to obtain the lightweight high-strength aluminum-based composite material.

6. The in-situ synthesis and preparation process of the lightweight high-strength aluminum-based composite material according to claim 5, characterized in that, Before step S2, the specific preparation method of the preform of the composition includes: weighing the powders of each component under an argon protective atmosphere, mixing them evenly in a mixing tank; filling the mixed powder into a mold, and applying it at room temperature. Unidirectional load and pressure holding The pressure is released and the mold is demolded to obtain a preform of the composition with the desired density.

7. The in-situ synthesis and preparation process of the lightweight high-strength aluminum-based composite material according to claim 5, characterized in that, The specific process parameters for step S2 are as follows: the preform of the composition is vertically pressed into the molten aluminum, with an immersion depth equal to the total depth of the molten aluminum. ;Keep constant temperature Furthermore, during this isothermal reaction stage, the mechanical stirring equipment is turned off to keep the melt macroscopically still.

8. The in-situ synthesis and preparation process of the lightweight high-strength aluminum-based composite material according to claim 5, characterized in that, The specific implementation of step S3 is as follows: a titanium alloy stirring paddle coated with a boron nitride protective layer is inserted into the melt for stirring, and the stirring paddle speed is set to [speed value missing]. Continue stirring .

9. The in-situ synthesis and preparation process of the lightweight high-strength aluminum-based composite material according to claim 5, characterized in that, The specific process parameters for degassing and refining in step S4 are as follows: a rotary jet degassing machine is used for processing, with the graphite rotor penetrating deep into the bottom of the melt. At this location, the rotation speed is set to At the same time, the incoming flow is High-purity argon gas, continuously degassing .

10. The in-situ synthesis and preparation process of the lightweight high-strength aluminum-based composite material according to claim 5, characterized in that, During the smelting process in step S1, a flow rate of [flow rate missing] is continuously introduced at the top of the crucible. Argon gas; In the casting process of step S4, the refined composite material melt is smoothly poured to the preheated temperature. In the metal mold.

Images