Preparation method of aluminum titanium carbon boron refiner for improving dispersibility of carbon particles

Abstract

The present application belongs to the technical field of aluminum alloy materials, and particularly relates to a preparation method of an aluminum-titanium-carbon-boron refiner for improving carbon particle dispersity. In view of the technical problems that carbon particles are difficult to uniformly disperse in aluminum liquid due to poor wettability, easy agglomeration and floating, the present application performs pre-dispersion treatment on the carbon particles, and combines high-temperature melt forced introduction and strengthened stirring dispersion, so that the carbon particles are uniformly and stably distributed in the aluminum matrix, carbon particle agglomeration, floating and burning loss are effectively inhibited, and the effective introduction rate of the carbon particles and the structure uniformity of the refiner are significantly improved. The aluminum-titanium-carbon-boron refiner prepared by the present application provides a large number of dispersed distribution of heterogeneous nucleation points in the aluminum alloy solidification process, significantly increases the number of nucleation, thereby refining the grains, helps to optimize the microstructure of the aluminum alloy, has good grain refinement ability, thermal stability and anti-element poisoning performance, and is suitable for industrialized production and application of Cr-containing aluminum alloys.

Description

Technical Field

[0001] This invention belongs to the field of aluminum alloy materials technology, and relates to a method for preparing an aluminum-titanium-carbon-boron refining agent to improve the dispersion of carbon particles. Background Technology

[0002] Aluminum and aluminum alloys, due to their low density, high specific strength, excellent corrosion resistance, and superior electrical and thermal conductivity, have become important structural materials in key fields such as aerospace, transportation engineering, and high-voltage power transmission. However, existing aluminum alloys still fall short in terms of absolute strength and thermal stability, severely hindering their application in heavy-duty and other high-end working conditions, thus hindering the "aluminum replacing steel" process. Grain refinement is the most critical process for simultaneously improving the strength and plasticity of aluminum alloys, and aluminum-titanium-boron (Al-Ti-B) master alloys are widely used in industry as grain refiners. However, traditional Al-Ti-B grain refiners are prone to failure when exposed to transition elements, high-density particles tend to settle and segregate, and excessive addition can lead to the precipitation of brittle phases, deteriorating plasticity.

[0003] In recent years, carbon has been recognized for its ability to form high-temperature stable phases such as Al4C3 or TiC in situ. Its crystal lattice exhibits excellent coherent or semi-coherent relationships with the aluminum matrix, providing a highly efficient and poison-resistant heterogeneous nucleation substrate. Simultaneously, carbon nanotubes, graphene, and other nanomaterials possess both high aspect ratios and mechanical reinforcing properties, making them ideal additives for overcoming the limitations of traditional refining agents. However, achieving effective solid solution and uniform dispersion of carbon in aluminum alloy melts still faces the following challenges: (1) At the eutectic temperature, the solid solubility of carbon in liquid aluminum is only about 0.03 wt%, and solid solution can hardly be achieved by ordinary thermodynamic diffusion; (2) The surface energy of nano-carbon materials is extremely high, and the contact angle with liquid aluminum exceeds 90°. The strong repulsive effect makes it extremely difficult for them to penetrate and wet the liquid aluminum without interface modification. (3) The density of carbon powder is much lower than that of aluminum melt, and it is very easy to agglomerate due to van der Waals forces. When added directly, carbon particles often float on the surface of the melt or form large particles that float to the surface. They are easily burned by high temperature or entrained in the oxide slag, resulting in a very low yield and extremely uneven micro-distribution.

[0004] Therefore, there is an urgent need for an aluminum-titanium-carbon-boron finer agent to improve the solubility and dispersibility of carbon in molten aluminum. Summary of the Invention

[0005] In view of the above-mentioned defects in the prior art, the purpose of this invention is to overcome the technical problems such as the extremely low solid solubility of carbon in aluminum melt, poor interfacial wettability, and easy agglomeration, floating and burning loss, and to provide a method for preparing an aluminum-titanium-carbon-boron finer agent to improve the dispersibility of carbon particles.

[0006] To achieve the above objectives, the technical solution adopted by the present invention is as follows: A method for preparing an aluminum-titanium-carbon-boron particle refiner to improve carbon particle dispersion includes the following steps: S1. Mix aluminum powder, nano-sized carbon particles and fluorine-containing activator at a mass ratio of 10:(4~6):(0.5~1.2) and ball mill under argon protection for 2~4 hours to obtain aluminum-carbon composite powder; S2. Heat the aluminum ingot to 730~750℃ and melt it. Add aluminum-titanium master alloy and aluminum-boron master alloy in sequence. Stir electromagnetically for 20~40 minutes to obtain alloy melt. Then add refining agent and degas with argon for 10~20 minutes to obtain primary refined aluminum liquid. S3. Heat the primary aluminum liquid prepared above to 780~820℃, and evenly sprinkle solid flux on the surface of the primary aluminum liquid to form a flux covering layer on the surface of the primary aluminum liquid. Then, use the pre-made block immersion method or deep melting carrier gas blowing method to add the aluminum-carbon composite powder prepared in step S1 to the primary aluminum liquid to obtain an intermediate melt. S4. Cool the intermediate melt prepared above to 710~730℃, stir at the temperature for 0.5~1.5h, and after stirring, introduce argon gas for 10~20min to obtain the alloy melt. S5. Adjust the temperature of the above alloy melt to 700~720℃, and then perform semi-continuous casting at a casting speed of 90~100mm / s to obtain an aluminum alloy ingot. After cooling the aluminum alloy ingot, heat it to 350~400℃ and extrude it into an alloy rod to obtain an aluminum-titanium-carbon-boron refining agent.

[0007] Preferably, the nanoscale carbon particles in step S1 are one of multi-walled carbon nanotubes and nano-graphite powder, or a mixture of the two in any proportion; the outer diameter of the multi-walled carbon nanotubes is 10~50nm and the length is 1~20μm, and the median particle size of the nano-graphite powder is 20~100nm. The fluorinated activator is one of potassium fluorotitanate, potassium fluoroborate, and aluminum fluoride, or a mixture of multiple substances in any proportion.

[0008] Preferably, in step S2, the mass ratio of the refining agent to the alloy melt is 1:(250~1000); the refining agent is potassium hexafluoroaluminate or potassium tetrafluoroaluminate.

[0009] Preferably, the mass ratio of aluminum ingot, aluminum-titanium master alloy and aluminum-boron master alloy in step S2 is 100:(35~55):(8~15); The aluminum-titanium master alloy is one of AlTi5, AlTi10, or AlTi15; the aluminum-boron master alloy is one of AlB3, AlB5, or AlB10.

[0010] Preferably, the solid flux in step S3 is a mixture of sodium chloride, potassium chloride and cryolite in a mass ratio of 4:4:2 or a mixture of sodium chloride and potassium chloride in a mass ratio of 1:1.

[0011] Preferably, the specific operation of the precast block immersion method in step S3 is as follows: S301. The aluminum-carbon composite powder prepared in step S1 is cold-pressed into a preform blank. The preform blank is placed in a protective atmosphere furnace and held at 655°C for 0.5~2h for solid-state sintering to obtain a composite preform. S302. Press the above-mentioned composite preform into the primary aluminum melt in batches below the surface, and simultaneously perform mechanical stirring and induction electromagnetic stirring to obtain an intermediate melt.

[0012] Preferably, the specific operation of the deep melting carrier gas injection method in step S3 is as follows: S311. Place the spray nozzle of the spray gun at a distance of 10-15cm from the bottom of the primary aluminum melt. S312. Under electromagnetic stirring conditions, using argon as the carrier gas and the composite powder prepared in step S1 as the injection material, an intermediate melt is prepared.

[0013] Preferably, the mass ratio of the aluminum-carbon composite powder to the primary molten aluminum is (70~160):100.

[0014] Preferably, the diameter of the aluminum alloy ingot in step S5 is 245 mm, and the diameter of the alloy rod is 10~13 mm.

[0015] Preferably, the carbon content in the aluminum-titanium-carbon-boron refining agent described in step S5 is 15-20%.

[0016] Compared with the prior art, the present invention has the following beneficial effects: (1) This invention solves the problems of carbon being difficult to wet, easily agglomerated, easily floating and difficult to uniformly introduce in aluminum liquid through the synergistic process of mechanical alloying pre-made composite powder, high temperature melt forced dispersion and low temperature long-term stirring, so that the carbon content in the finer agent can be stably reached 15~20% and uniform dispersion can be achieved.

[0017] (2) When the refining agent prepared in this invention is applied to aluminum alloys, the refining effect can be significantly enhanced. Under the same addition amount and processing conditions, the tensile strength of the aluminum alloy is increased by more than 50 MPa compared with the traditional aluminum-titanium-boron refining agent, with an increase of more than 12%, and the elongation is still maintained at more than 10%. Detailed Implementation

[0018] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below. Where specific conditions are not specified in the embodiments, conventional conditions or conditions recommended by the manufacturer shall apply. Reagents or instruments whose manufacturers are not specified are all conventional products that can be purchased commercially.

[0019] To achieve the above-mentioned objectives of the present invention, the technical solution of the present invention will be further described in detail below, but the scope of protection of the present invention is not limited to the following description.

[0020] A typical embodiment of the present invention provides a method for preparing an aluminum-titanium-carbon-boron particle refiner to improve carbon particle dispersion, comprising the following steps: S1. Mix aluminum powder, nano-sized carbon particles and fluorine-containing activator at a mass ratio of 10:(4~6):(0.5~1.2) and ball mill under argon protection for 2~4 hours to obtain aluminum-carbon composite powder; In one or more embodiments of this implementation, the nanoscale carbon particles are one of multi-walled carbon nanotubes and nano-graphite powder, or a mixture of the two in any proportion.

[0021] In one or more embodiments of this implementation, the fluorinated activator is one of potassium fluorotitanate, potassium fluoroborate, and aluminum fluoride, or a mixture of multiple substances in any proportion.

[0022] S2. Heat the aluminum ingot to 730~750℃ and melt it. Add aluminum-titanium master alloy and aluminum-boron master alloy in sequence. Stir electromagnetically for 20~40 minutes to obtain alloy melt. Then add refining agent and degas with argon for 10~20 minutes to obtain primary refined aluminum liquid. The mass ratio of the refining agent to the alloy melt is 1:(250~1000). In one or more embodiments of this implementation, the mass ratio of the aluminum ingot, the aluminum-titanium master alloy, and the aluminum-boron master alloy is 100:(35~55):(8~15); the aluminum-titanium master alloy is one of AlTi5, AlTi10, or AlTi15; and the aluminum-boron master alloy is one of AlB3, AlB5, or AlB10.

[0023] S3. Heat the primary aluminum liquid prepared above to 780~820℃, and evenly sprinkle solid flux on the surface of the primary aluminum liquid to form a flux covering layer on the surface of the primary aluminum liquid. Then, add the aluminum-carbon composite powder prepared in step S1 to the primary aluminum liquid using the pre-made block immersion method or the deep melting carrier gas blowing method to obtain an intermediate melt. The mass ratio of the aluminum-carbon composite powder to the primary aluminum liquid is (70~160):100.

[0024] In some embodiments, a precast block immersion method is used. The specific operation of the precast block immersion method is as follows: S301. The aluminum-carbon composite powder prepared in step S1 is cold-pressed into a preform blank. The preform blank is placed in a protective atmosphere furnace and held at 655°C for 0.5~2h for solid-state sintering to obtain a composite preform. S302. Press the above composite preform into the surface of the primary aluminum melt in batches, and simultaneously perform mechanical stirring and induction electromagnetic stirring to achieve rapid wetting of carbon. Utilize the in-situ exothermic reaction of fluoride salts in the preform to destroy the gas film at the carbon particle interface. Maintain the temperature at 780~820℃. After the addition is complete, argon gas is introduced for degassing for 5~15 minutes to obtain the intermediate melt. The solid-state sintered aluminum-carbon preforms are divided into 3-5 batches. Using a high-temperature resistant graphite bell jar or mechanical press head, each batch of preforms is forcibly pressed into the molten aluminum at a depth of 15-30 cm below the surface. Under the condition of maintaining mechanical stirring and induction electromagnetic stirring, after the batch of preforms has completely melted and reacted, and the temperature of the intermediate melt has risen back to the preset temperature, the next batch of preforms is pressed in after a 5-10 minute interval. The above-mentioned batch deep pressing method can effectively avoid the sudden drop in local temperature of the melt caused by adding it all at once, prevent metal splashing caused by excessive reaction, and provide sufficient wetting time for the uniform dispersion of carbon particles in the molten aluminum, thus completely eliminating carbon agglomeration defects.

[0025] In some embodiments, a deep-melting carrier gas injection method is used, which can fully wet and uniformly distribute carbon elements at high temperatures. The specific operation of the deep-melting carrier gas injection method is as follows: S311. Place the spray nozzle of the spray gun at a distance of 10-15cm from the bottom of the primary aluminum melt. S312. Under electromagnetic stirring conditions, argon is used as the carrier gas, and the aluminum-carbon composite powder prepared in step S1 is used as the injection material and injected into the primary aluminum liquid. During the injection process, the temperature of the aluminum liquid is maintained at ≥780℃. After the injection is completed, argon is introduced to degas for 10~20 minutes to prepare an intermediate melt. S4. Cool the intermediate melt prepared above to 710~730℃, stir at the temperature for 0.5~1.5h, and after stirring, introduce argon gas for 10~20min to obtain the alloy melt. S5. Adjust the temperature of the above alloy melt to 700~720℃, and then perform semi-continuous casting at a casting speed of 90~100mm / s to obtain an aluminum alloy ingot with a diameter of 245mm (Φ245mm). After cooling the aluminum alloy ingot, heat it to 350~400℃ and extrude it into an alloy rod with a diameter of 10~13mm (Φ12mm) to obtain an aluminum-titanium-carbon-boron refining agent.

[0026] Example 1 A method for preparing an aluminum-titanium-carbon-boron refining agent to improve carbon particle dispersibility, wherein step S3 employs a pre-block immersion method, as detailed below: S1. Aluminum powder, multi-walled carbon nanotubes and potassium fluorotitanate are mixed in a mass ratio of 10:5:0.8 and ball-milled for 3 hours under argon protection to obtain aluminum-carbon composite powder. S2. Weigh out 100 parts of aluminum ingot, 45 parts of AlTi10 master alloy, and 12 parts of AlB5 master alloy, and set aside. Then heat the aluminum ingot to 740℃ to melt it, add AlTi10 master alloy and AlB5 master alloy in sequence, stir electromagnetically for 30 minutes, add potassium hexafluoroaluminate refining agent, and degas with argon for 15 minutes to obtain primary refined aluminum liquid. The mass ratio of the refining agent to the alloy melt is 1:625. S3. The above-prepared primary aluminum liquid is heated to 800°C, and a solid flux is evenly sprinkled on the surface of the primary aluminum liquid to form a covering layer; then, the aluminum-carbon composite powder prepared in step S1 is added to the primary aluminum liquid using the pre-formed block immersion method to obtain an intermediate melt; the mass ratio of the aluminum-carbon composite powder to the primary aluminum liquid is 110:100, and the solid solvent is a compound of sodium chloride, potassium chloride and cryolite in a mass ratio of 4:4:2; The specific operation of the precast block immersion method is as follows: S301. The composite powder is cold-pressed into a Φ5cm×10cm preform blank, and then placed in a protective atmosphere furnace and held at 655℃ for 1h for solid-state sintering to obtain the composite preform. S302. The composite preforms prepared above are pressed into the bottom of the primary aluminum liquid in 5 batches. The amount added in each batch is about 2% of the total amount of primary aluminum liquid. At the same time, mechanical stirring and induction electromagnetic stirring are turned on, and the temperature is maintained at 800℃. After the addition is completed, argon gas is introduced for degassing for 10 minutes to obtain intermediate melt. S4. Cool the above intermediate melt to 720°C and continue stirring for 1 hour, then introduce argon gas for 15 minutes to obtain the alloy melt. S5. Adjust the temperature of the above alloy melt to 710℃, semi-continuously cast it into a Φ245mm aluminum alloy ingot at a casting speed of 95mm / s, cool it, heat it to 380℃ and extrude it into a Φ12mm alloy rod to obtain an aluminum-titanium-carbon-boron refining agent.

[0027] Example 2 A method for preparing an aluminum-titanium-carbon-boron refining agent to improve carbon particle dispersibility, wherein step S3 employs a deep-melting carrier gas injection method, as detailed below: S1. Aluminum powder, multi-walled carbon nanotubes and potassium fluorotitanate are mixed in a mass ratio of 10:6:1.2 and ball-milled for 4 hours under argon protection to obtain aluminum-carbon composite powder. S2. Weigh 100 parts of aluminum ingot, 55 parts of AlTi10 master alloy, and 15 parts of AlB5 master alloy for later use; then heat the aluminum ingot to 750℃ to melt it, add AlTi5 master alloy and AlB3 master alloy in sequence, stir electromagnetically for 30 minutes, add potassium tetrafluoroaluminate refining agent, and degas with argon for 20 minutes to obtain primary refined aluminum liquid; the mass ratio of the refining agent to the alloy melt is 1:250. S3. The above-prepared primary aluminum liquid is heated to 820°C, and a solid flux is evenly sprinkled on the surface of the primary aluminum liquid to form a covering layer; then, the aluminum-carbon composite powder prepared in step S1 is added to the primary aluminum liquid using a deep melting carrier gas blowing method to obtain an intermediate melt; the mass ratio of the aluminum-carbon composite powder to the primary aluminum liquid is 160:100, and the solid solvent is a mixture of sodium chloride and potassium chloride with a mass ratio of 1:1; The specific operation of the deep-melting carrier gas injection method is as follows: S311. Position the spray gun nozzle 12cm from the bottom of the molten aluminum. S312. Under electromagnetic stirring conditions, using argon as a carrier, the aluminum-carbon composite powder prepared in step S1 is injected into the primary aluminum melt as a blowing material. During the blowing process, the temperature of the aluminum melt is maintained at ≥780℃. After the blowing is completed, argon is introduced to degas for 15 minutes to obtain the alloy melt. S4. Cool the above alloy melt to 730℃ and continue stirring for 0.5h, then introduce argon gas for 10min to obtain the alloy melt; S5. Adjust the temperature to 720℃, semi-continuously cast the above alloy melt into a Φ245mm aluminum alloy ingot at a casting speed of 90mm / s, cool it, heat it to 400℃ and extrude it into a Φ10mm alloy rod to obtain an aluminum-titanium-carbon-boron refining agent.

[0028] Example 3 A method for preparing an aluminum-titanium-carbon-boron particle refiner to improve carbon particle dispersibility includes the following steps: S1. Aluminum powder, composite carbon powder and potassium fluorotitanate are mixed in a mass ratio of 10:4:0.5 and ball-milled for 2 hours under argon protection to obtain aluminum-carbon composite powder; the composite carbon powder is a mixture of multi-walled carbon nanotubes and nano-graphite powder in a mass ratio of 1:1. S2. Weigh 100 parts of aluminum ingot, 35 parts of AlTi10 master alloy, and 8 parts of AlB5 master alloy for later use; then heat the aluminum ingot to 730℃ to melt it, add AlTi15 master alloy and AlB10 master alloy in sequence, stir electromagnetically for 20 minutes, add potassium hexafluoroaluminate refining agent, and degas with argon for 10 minutes to obtain primary refined aluminum liquid; the mass ratio of the refining agent to the alloy melt is 1:1000. S3. Heat the prepared primary aluminum liquid to 780°C, and evenly sprinkle solid flux onto the surface of the primary aluminum liquid to form a covering layer; then use the pre-made block immersion method, specifically referring to S301~S302 in Example 1, to adjust the mass ratio of aluminum-carbon composite powder to primary aluminum liquid to 70:100. The solid solvent is a compound of sodium chloride, potassium chloride and cryolite in a mass ratio of 4:4:2; other operations and parameters are completely consistent with Example 1. S4. Cool the intermediate melt prepared above to 710°C, stir at the temperature for 1.5 h, and after stirring, introduce argon gas for 20 min to obtain the alloy melt. S5. Adjust the temperature of the above alloy melt to 700℃, and then perform semi-continuous casting at a casting speed of 100mm / s to obtain a Φ245mm aluminum alloy ingot. After cooling the aluminum alloy ingot, heat it to 350℃ and extrude it into a Φ13mm alloy rod to obtain an aluminum-titanium-carbon-boron refining agent.

[0029] Comparative Example 1 Compared with Example 1, the fluorinated activator in step S1 does not participate in the reaction, and other operations and parameters are completely consistent with Example 1.

[0030] Comparative Example 2 Compared with Example 1, solid-state sintering is not performed in step S3. Instead, the preformed billet is directly pressed into the primary aluminum molten metal. Other operations and parameters are completely consistent with those in Example 1.

[0031] Comparative Example 3 Compared with Example 1, the mass ratio of aluminum powder, multi-walled carbon nanotubes and potassium fluorotitanate was adjusted to 10:8:0.8, and other operations and parameters were completely consistent with the Example 1.

[0032] control group Traditional AlTi5B1 aluminum-titanium-boron refining agent is used.

[0033] The refining agents prepared above were evaluated mainly based on the following physicochemical properties: (1) Carbon content: High-frequency infrared carbon-sulfur analysis method was used; (2) Carbon content distribution: The carbon content of the same casting rod is measured at three points: top, middle and bottom, and the range is calculated.

[0034] When the aluminum-titanium-carbon-boron refining agent prepared in this invention is applied to aluminum alloys, the evaluation mainly focuses on tensile strength and elongation: (1) Tensile strength: room temperature tensile test, using GB / T 228.1-2010, 50KN electronic tensile testing machine; (2) Elongation: room temperature tensile test, using GB / T 228.1-2010, 50KN electronic tensile tester.

[0035] As shown in Table 1 below, the aluminum-titanium-carbon-boron refining agents prepared in Examples 1-3 all exhibited good performance compared with the control group. Specifically, when using the traditional AlTi5B1 aluminum-titanium-boron refining agent, the tensile strength of the aluminum alloy was only 403.4~410.1 MPa, while after using the aluminum-titanium-carbon-boron refining agent prepared in Example 1 of this invention, the tensile strength increased to 455.6~463.3 MPa, an increase of about 12%, while the elongation remained at 10.1%~10.9%, meeting the basic requirements of power fittings for plasticity.

[0036] To investigate the effects of fluorinated activators on improving carbon particle size, the effectiveness of solid-state sintering in dispersing carbon particles in primary aluminum molten metal, and the effectiveness of the aluminum-carbon ratio, comparative examples 1-3 were designed, and the specific analyses are as follows: (1) By comparing Example 1 and Comparative Example 1, without the addition of a fluorinated activator, the actual carbon content decreased from 18.6% to 12.1%, a decrease of approximately 35%, the distribution uniformity increased from 0.21% to 1.85%, an increase of nearly 8 times, the grain size increased from ≤35μm to approximately 65μm, and the tensile strength decreased by approximately 40MPa. This indicates that the fluorinated activator can effectively improve the interfacial wettability between carbon particles and molten aluminum.

[0037] (2) By comparing Example 1 and Comparative Example 2, the data shows that the carbon content of the grain refiner prepared by directly adding the cold-pressed block without pre-sintering at 655℃ decreased from 18.6% to 9.8%, a decrease of approximately 47%; the carbon distribution uniformity increased from 0.21% to 3.42%, an increase of approximately 16 times, and the grain refinement effect was severely reduced. It is speculated that the unpre-sintered pre-block rapidly disintegrated in the aluminum melt, and the carbon particles re-agglomerated and floated to the surface, resulting in a significant decrease in carbon retention and dispersibility.

[0038] (3) By increasing the proportion of carbon, the data shows that although the carbon content reached 19.5%, the uniformity of distribution deteriorated significantly, with a range as high as 1.62%. The grain size also increased to about 70 μm, the tensile strength decreased to 425.8 MPa, and the elongation decreased to 8.5%. It is speculated that this is because the excessive carbon particles exceeded the dispersion capacity of the aluminum liquid, resulting in particle agglomeration. Not only could it not play a refining role, but it also became a crack source, damaging the plasticity and strength of the material.

[0039] Finally, it should be noted that although embodiments of the present invention have been shown and described, those skilled in the art will understand that various changes, modifications, substitutions and variations can be made to these embodiments without departing from the principles and spirit of the present invention. All equivalent changes and improvements made within the scope of the present invention should still fall within the scope of the present invention.

Claims

1. A method for preparing an aluminum-titanium-carbon-boron particle refiner to improve carbon particle dispersibility, characterized in that, Includes the following steps: S1. Mix aluminum powder, nano-sized carbon particles and fluorine-containing activator at a mass ratio of 10:(4~6):(0.5~1.2) and ball mill under argon protection for 2~4 hours to obtain aluminum-carbon composite powder; S2. Heat the aluminum ingot to 730~750℃ and melt it. Add aluminum-titanium master alloy and aluminum-boron master alloy in sequence. Stir electromagnetically for 20~40 minutes to obtain alloy melt. Then add refining agent and degas with argon for 10~20 minutes to obtain primary refined aluminum liquid. S3. Heat the primary aluminum liquid prepared above to 780~820℃, and evenly sprinkle solid flux on the surface of the primary aluminum liquid to form a flux covering layer on the surface of the primary aluminum liquid. Then, use the pre-made block immersion method or deep melting carrier gas blowing method to add the aluminum-carbon composite powder prepared in step S1 to the primary aluminum liquid to obtain an intermediate melt. S4. Cool the intermediate melt prepared above to 710~730℃, stir at the temperature for 0.5~1.5h, and after stirring, introduce argon gas for 10~20min to obtain the alloy melt. S5. Adjust the temperature of the above alloy melt to 700~720℃, and then perform semi-continuous casting at a casting speed of 90~100mm / s to obtain an aluminum alloy ingot. After cooling the aluminum alloy ingot, heat it to 350~400℃ and extrude it into an alloy rod to obtain an aluminum-titanium-carbon-boron refining agent.

2. The method for preparing the aluminum-titanium-carbon-boron finer agent for improving carbon particle dispersibility according to claim 1, characterized in that, The nanoscale carbon particles mentioned in step S1 are one of multi-walled carbon nanotubes and nano-graphite powder, or a mixture of the two in any proportion; the outer diameter of the multi-walled carbon nanotubes is 10~50nm and the length is 1~20μm, and the median particle size of the nano-graphite powder is 20~100nm. The fluorinated activator is one of potassium fluorotitanate, potassium fluoroborate, and aluminum fluoride, or a mixture of multiple substances in any proportion.

3. The method for preparing the aluminum-titanium-carbon-boron finer agent for improving carbon particle dispersibility according to claim 1, characterized in that, In step S2, the mass ratio of the refining agent to the alloy melt is 1:(250~1000); the refining agent is potassium hexafluoroaluminate or potassium tetrafluoroaluminate.

4. The method for preparing the aluminum-titanium-carbon-boron finer agent for improving carbon particle dispersibility according to claim 3, characterized in that, The mass ratio of the aluminum ingot, aluminum-titanium master alloy, and aluminum-boron master alloy in step S2 is 100:(35~55):(8~15); The aluminum-titanium master alloy is one of AlTi5, AlTi10, or AlTi15; the aluminum-boron master alloy is one of AlB3, AlB5, or AlB10.

5. The method for preparing the aluminum-titanium-carbon-boron finer agent for improving carbon particle dispersibility according to claim 3, characterized in that, The solid flux in step S3 is a mixture of sodium chloride, potassium chloride and cryolite in a mass ratio of 4:4:2 or a mixture of sodium chloride and potassium chloride in a mass ratio of 1:

1.

6. The method for preparing the aluminum-titanium-carbon-boron finer agent for improving carbon particle dispersibility according to any one of claims 1 to 5, characterized in that, The specific operation of the precast block immersion method described in step S3 is as follows: S301. The aluminum-carbon composite powder prepared in step S1 is cold-pressed into a preform blank. The preform blank is placed in a protective atmosphere furnace and held at 655°C for 0.5~2h for solid-state sintering to obtain a composite preform. S302. Press the above-mentioned composite preform into the primary aluminum melt in batches below the surface, and simultaneously perform mechanical stirring and induction electromagnetic stirring to obtain an intermediate melt.

7. The method for preparing the aluminum-titanium-carbon-boron finer agent for improving carbon particle dispersibility according to any one of claims 1 to 5, characterized in that, The specific operation of the deep melting carrier gas injection method described in step S3 is as follows: S311. Place the spray nozzle of the spray gun at a distance of 10-15cm from the bottom of the primary aluminum melt. S312. Under electromagnetic stirring conditions, using argon as the carrier gas and the composite powder prepared in step S1 as the injection material, an intermediate melt is prepared.

8. The method for preparing the aluminum-titanium-carbon-boron finer agent for improving carbon particle dispersibility according to claim 7, characterized in that, The mass ratio of the aluminum-carbon composite powder to the primary molten aluminum is (70~160):

100.

9. The method for preparing the aluminum-titanium-carbon-boron finer agent for improving carbon particle dispersibility according to claim 1, characterized in that, The diameter of the aluminum alloy ingot in step S5 is 245mm, and the diameter of the alloy rod is 10~13mm.

10. The method for preparing the aluminum-titanium-carbon-boron finer agent for improving carbon particle dispersibility according to claim 1, characterized in that, The carbon content in the aluminum-titanium-carbon-boron refining agent described in step S5 is 15-20%.

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