Grain refiners, aluminum materials, preparation methods and applications

Abstract

This invention discloses a grain refiner, an aluminum material, a preparation method, and its applications. The grain refiner has a chemical composition comprising Al, Ti, C, and RE; wherein, based on the total weight of the grain refiner, the Ti content is 0.1–5.5 wt%, the C content is 0.01–1.0 wt%, the RE content is 0.01–1.0 wt%, and the Al content is 93–98 wt%; the RE is La and / or Ce. The grain refiner of this invention produces a fine-sized, dispersed, and uniformly composed grain refiner, which can reduce the grain size of the refined aluminum to below 90 μm.

Description

Technical Field

[0001] This invention relates to a grain refiner, aluminum material, preparation method, and applications. Background Technology

[0002] Grain refinement of aluminum alloys can result in a dense alloy microstructure, while also reducing the tendency for hot cracking and segregation in castings, lowering porosity, and thus improving the overall performance of the alloy. Currently, the most common and effective grain refinement method is the addition of grain refiners. Aluminum-titanium-carbon (ATC) grain refiners have gained widespread attention and application due to their finer TiC refining phase, uniform distribution, and resistance to aggregation, as well as their better coherence with Al, resulting in a better grain refinement effect than traditional ATC-boron grain refiners. However, the poor wettability of C in Al makes preparation very difficult. The high cost of preparing ATC grain refiners through vigorous stirring or high-temperature reactions limits their widespread application.

[0003] In recent years, researchers have focused on developing novel grain refiners to address the aforementioned problems. For example, CN1108277374A, CN102784905B, CN111363936A, and CN114150173A disclose methods for preparing Al-Ti-CY, Al-Ti-C-Er, Al-Ti-C-La, and Al-Ti-C-Sc grain refiners, respectively. These methods use graphite powder or carbon powder as the carbon source. However, due to the poor wettability of C with Al, C is difficult to penetrate, and the process requires high temperatures and is costly. CN100467635C discloses a method for preparing an aluminum-titanium-carbon master alloy, using aluminum-carbon and aluminum-titanium alloys as raw materials. While the process is simple, it is costly and results in a large-sized refined phase. CN112899512B discloses a grain refiner for aluminum-titanium-carbon alloys and its preparation method, which uses nano-sized TiC as the carbon source. This method is costly, and the added TiC particles have poor wettability with Al, making it difficult to ensure uniform distribution of TiC in the Al melt. CN111996424B discloses a method for manufacturing a TCB-Al seed alloy and a heritable aluminum alloy, using an Al-Al3BC intermediate alloy as the carbon source. This intermediate alloy is first prepared using powder metallurgy and then added to pure aluminum as the carbon source. However, this method has a long process, high cost, and difficulty in controlling boron-doped TiC. B The content of.

[0004] CN108411139A discloses an Al-Ti-C-Sr composite grain refiner, alloy, and its preparation method. The grain refiner of this invention is prepared by melting a base material and SrO powder. The base material includes aluminum powder, titanium powder, and graphite powder in a mass ratio of 5:(1.5~2.5):(0.8~1.2), with SrO powder comprising 0.5~6% of the base material. This invention involves mechanically ball-milling a mixture of SrO powder and the base material for 2 hours, pressing the powder into cylindrical preforms. Raw aluminum is first melted in a graphite crucible, and the preforms are pressed into the molten aluminum at 800℃. The mass of the preforms is 0.1~0.4% of the raw aluminum. The mixture is held at this temperature for 5~20 minutes, and after slag removal, it is poured into a metal mold to obtain the Al-Ti-C-Sr alloy. Although this method can reduce the size of pure aluminum or aluminum alloys, specific reference data is not provided.

[0005] CN114606415A discloses an aluminum and aluminum alloy grain refiner provided by this invention. The aluminum and aluminum alloy grain refiner of this invention comprises Ti 2.0–6.0%, B 0.1–3.0%, Nb 0.1–5.0%, C 0.02–0.5%, Ce 0.02–1.0%, with the remainder being aluminum. This invention, by simultaneously adding C, Ce, and Nb elements, achieves a better grain refinement effect on aluminum grains, refining them to below 150 μm. The grain size obtained in this patent document is still relatively large. Summary of the Invention

[0006] In view of this, one object of the present invention is to provide a grain refiner, which refines phases with small size, dispersed distribution, and uniform composition, thereby reducing the grain size of refined aluminum to below 90 μm. Another object of the present invention is to provide a method for preparing the above-mentioned grain refiner, which has good process repeatability, a simple method for introducing carbon sources, low cost, and is easier to integrate into molten aluminum. A further object of the present invention is to provide a method for preparing an aluminum material. Yet another object of the present invention is to provide an aluminum material. A still another object of the present invention is to provide a use for the grain refiner.

[0007] On one hand, the present invention provides a grain refiner, wherein the chemical composition of the grain refiner includes Al, Ti, C and RE; wherein,

[0008] Based on the total weight of the grain refiner, the Ti content is 0.1–5.5 wt%, the C content is 0.01–1.0 wt%, the RE content is 0.01–1.0 wt%, and the Al content is 93–98 wt%; wherein the RE is La and / or Ce.

[0009] According to the grain refiner of the present invention, preferably, the chemical composition of the grain refiner is Al, Ti, C, RE and unavoidable impurities; wherein,

[0010] Based on the total weight of the grain refiner, the Ti content is 0.1–5.5 wt%, the C content is 0.01–1.0 wt%, the RE content is 0.01–1.0 wt%, and Al is the balance; the RE is La and / or Ce.

[0011] According to the grain refiner of the present invention, preferably, the chemical composition of the grain refiner is Al, Ti, C, La and unavoidable impurities; wherein,

[0012] Based on the total weight of the grain refiner, the Ti content is 1.0–5.0 wt%, the C content is 0.05–0.5 wt%, the La content is 0.1–0.5 wt%, and the Al content is the balance.

[0013] According to the grain refiner of the present invention, preferably, the chemical composition of the grain refiner is Al, Ti, C, Ce and unavoidable impurities; wherein,

[0014] Based on the total weight of the grain refiner, the Ti content is 1.0–5.0 wt%, the C content is 0.3–0.5 wt%, the Ce content is 0.1–0.5 wt%, and Al is the balance.

[0015] According to the grain refiner of the present invention, preferably, the chemical composition of the grain refiner is Al, Ti, C, RE and unavoidable impurities; wherein,

[0016] Based on the total weight of the grain refiner, the Ti content is 1.0–5.0 wt%, the C content is 0.05–0.5 wt%, the RE content is 0.5–1.0 wt%, and Al is the balance; the RE is La and Ce; the mass ratio of La to Ce is 1:1–3.

[0017] According to the grain refiner of the present invention, preferably, the alloy nucleation phases of the grain refiner include TiAl3 phase, TiC phase and Ti2Al phase. 20 One or more of the RE phases, with the matrix phase being the α-Al phase;

[0018] The size of the TiAl3 phase is less than or equal to 5 μm; Ti2Al 20 The size of the RE phase is less than or equal to 5 μm; the size of the TiC phase is less than or equal to 1 μm.

[0019] On the other hand, the present invention also provides a method for preparing the grain refiner according to the above description, comprising the following steps:

[0020] (1) Place cryolite, sodium chloride and potassium chloride in a graphite crucible and heat to prepare a salt solvent melt;

[0021] (2) Rare earth oxides and carbon-containing alumina powder are added to a salt solvent melt and stirred to uniformly disperse the rare earth oxides and carbon-containing alumina powder to form a liquid-solid mixture; the liquid-solid mixture is poured into a graphite crucible and cooled to obtain a precursor; the total volume of the rare earth oxides and carbon-containing alumina powder is 10-40% of the volume of the salt solvent melt; the rare earth oxides are lanthanum oxide and / or cerium oxide.

[0022] (3) Form aluminum melt from aluminum ingots; add potassium fluorotitanate to the aluminum melt in batches and stir, then add the precursor obtained in step (2), continue stirring until the reaction is complete, remove the salt solvent melt, and obtain the alloy solution.

[0023] (4) The alloy solution is sequentially refined, degassed, and slag removed to obtain a slag-removed alloy solution. The slag-removed alloy solution is further processed to obtain a grain refiner.

[0024] Furthermore, the present invention also provides a method for preparing aluminum material, comprising the following steps:

[0025] Aluminum raw material is melted to obtain a melt; a grain refiner as described above is added to the melt and mixed to obtain a molten metal; the molten metal is refined, degassed, and slag is removed, then cooled, and then solidified to obtain aluminum material.

[0026] The amount of the grain refiner added is 0.05% to 0.5% of the melt mass.

[0027] In another aspect, the present invention also provides an aluminum material prepared by the preparation method described above.

[0028] In another aspect, the present invention provides the use of the grain refiner described above in refining the grain size of aluminum.

[0029] The grain refiner of this invention produces grains with small, dispersed, and uniformly composed grains. The preparation method of this grain refiner exhibits high effective element yield and demonstrates better grain refining effect compared to grain refiners prepared using existing technologies. Furthermore, the preparation process is simpler and less costly. The preparation method of this invention involves the in-situ generation of TiC, TiAl3, and Ti2Al phases. 20 The RE phase method uses calcined aluminum citrate as a carbon source, making it easier for carbon to enter the molten aluminum and reducing costs. The grain refiner prepared by this invention increases the number density of effective nucleation sites, improving refinement efficiency. Compared to existing Al-Ti-C grain refiners, it allows for achieving the same refinement effect with a smaller amount of refiner added, thereby further reducing the cost of using grain refiners. Attached Figure Description

[0030] Figure 1 The images show the XRD results of the grain refiners obtained in Examples 1 and 3 of this invention.

[0031] Figure 2 is a morphology diagram of the grain refiner obtained in Example 2 of the present invention. Wherein, Figure 2a Microstructure diagram of TiC phase; Figure 2b This is a diagram showing the elemental distribution of the TiC phase. Figure 2c for Figure 2b A magnified view of a portion of the image.

[0032] Figure 3 This is a SEM image of the grain refiner obtained in Example 3 of the present invention.

[0033] Figure 4 The metallographic structure diagrams are obtained from the refined aluminum raw materials, Examples 4, 5, 6 and Comparative Example 2. Detailed Implementation

[0034] The present invention will be further described below with reference to specific embodiments, but the scope of protection of the present invention is not limited thereto.

[0035] <Grain refiner>

[0036] The grain refiner of the present invention can be used for refining aluminum. The chemical composition of the grain refiner includes Al, Ti, C and RE, and based on the total weight of the grain refiner, the Ti content is 0.1-5.5 wt%, the C content is 0.01-1.0 wt%, the RE content is 0.01-1.0 wt%, and the Al content is 93-98 wt%; wherein the RE is La and / or Ce.

[0037] RE represents rare earth elements. In some embodiments, RE is La; in others, RE is Ce; and in still others, RE is La and Ce. The mass ratio of La to Ce can be 1:1 to 3, preferably 1:1 to 2, and more preferably 1:1 to 1.7.

[0038] Based on the total weight of the grain refiner, the Ti content can be 0.1 to 5.5 wt%, preferably 1.0 to 5.0 wt%, and more preferably 3.0 to 5.0 wt%.

[0039] Based on the total weight of the grain refiner, the C content can be 0.01 to 1.0 wt%, preferably 0.01 to 0.5 wt%, and more preferably 0.1 to 0.5 wt%.

[0040] Based on the total weight of the grain refiner, the RE content can be 0.01 to 1.0 wt%, preferably 0.1 to 1.0 wt%, and more preferably 0.5 to 1.0 wt%.

[0041] Based on the total weight of the grain refiner, the Al content can be 93-98 wt%, preferably 94-97 wt%, and more preferably 95-97 wt%.

[0042] In some embodiments, the grain refiner has the chemical composition of Al, Ti, C, La, and unavoidable impurities; wherein,

[0043] Based on the total weight of the grain refiner, the Ti content is 1.0–5.0 wt%, the C content is 0.05–0.5 wt%, the La content is 0.1–0.5 wt%, and the Al content is the balance.

[0044] In other embodiments, the grain refiner has the chemical composition of Al, Ti, C, Ce, and unavoidable impurities; wherein,

[0045] Based on the total weight of the grain refiner, the Ti content is 1.0–5.0 wt%, the C content is 0.3–0.5 wt%, the Ce content is 0.1–0.5 wt%, and Al is the balance.

[0046] In some other embodiments, the grain refiner has the chemical composition of Al, Ti, C, RE, and unavoidable impurities; wherein,

[0047] Based on the total weight of the grain refiner, the Ti content is 1.0–5.0 wt%, the C content is 0.05–0.5 wt%, the RE content is 0.5–1.0 wt%, and Al is the balance; the RE is La and Ce; the mass ratio of La to Ce is 1:1–3.

[0048] This invention unexpectedly discovered that the grain refiner prepared using the Al-Ti-C-RE system and the preparation method of this invention can better refine aluminum materials, resulting in finer grains. This invention believes this is because rare earth atoms, especially La or Ce, contribute to the refinement and uniform distribution of the TiC and TiAl3 phases. Furthermore, La or Ce atoms have a degassing and impurity-removing effect in aluminum, and the REA1 phase formed by rare earth elements and Al can act as heterogeneous nucleation sites, thus refining the grains and improving the alloy quality and grain refinement effect.

[0049] The alloy nucleation phases of the grain refiner of the present invention include TiAl3 phase, TiC phase and Ti2Al phase. 20 One or more of the RE phase, with the matrix phase being the α-Al phase; preferably, the alloy nucleating particle phase of the grain refiner of the present invention consists of TiAl3 phase, TiC phase and Ti2Al phase.20 Multiple compositions in the RE phase.

[0050] The size of the TiAl3 phase is less than or equal to 5 μm, preferably less than or equal to 3 μm; Ti2Al 20 The size of the RE phase is less than or equal to 5 μm, preferably less than or equal to 3 μm; the size of the TiC phase is less than or equal to 1 μm, preferably less than or equal to 0.5 μm.

[0051] <Preparation method of grain refiner>

[0052] The preparation method of the above-mentioned grain refiner of the present invention includes the following steps: (1) preparation of precursor; (2) preparation of alloy solution; (3) preparation of grain refiner.

[0053] Existing technologies typically involve directly sintering aluminum ingots, carbon / graphite powder, and titanium powder to form alloy ingots, or directly forming a melt from aluminum ingots, carbon / graphite powder, and potassium fluorotitanate, followed by casting to form an alloy. This invention, however, uses vacuum calcination of aluminum citrate to form carbon-containing alumina powder as a carbon source. Rare earth oxides and carbon-containing alumina powder are added to a salt solvent of cryolite, sodium chloride, and potassium chloride, cooled to form a precursor. Then, aluminum ingots are formed into a melt, and potassium fluorotitanate, the rare earth precursor, and the carbon-containing alumina powder are added to the melt. The salt solvent melt is then removed to obtain an alloy solution. This method facilitates the dispersion of rare earth and carbon atoms, improves reaction efficiency, and helps prevent the precipitation of finer phases. This invention first utilizes a fluoride salt reaction to reduce Ti atoms from potassium fluorotitanate, then performs an aluminothermic reduction to reduce rare earth atoms from rare earth oxides. The Ti atoms in the reaction solution subsequently react with C and Al atoms in situ to form fine TiC and TiAl3 phases, as well as Ti2Al phase. 20 The rare earth elements (RE) phase enhance the refining effect of the TiC and TiAl3 phases. Furthermore, rare earth atoms inhibit the aggregation and growth of the refining phases, and excess atoms play a role in degassing, impurity removal, and refining of the aluminum material, thereby improving its quality.

[0054] Preparation of precursors

[0055] This invention uses cryolite, sodium chloride, and potassium chloride to form a salt solvent melt, which is then used as a solvent to form a precursor containing rare earth elements and carbon. This facilitates the dispersion of rare earth elements and carbon, improves reaction efficiency, and helps prevent the precipitation of finer phases.

[0056] Based on the total weight of the salt solvent melt, cryolite comprises 30–60 wt%, sodium chloride 20–40 wt%, and potassium chloride 15–40 wt%. Preferably, based on the total weight of the salt solvent melt, cryolite comprises 40–60 wt%, sodium chloride 20–35 wt%, and potassium chloride 15–30 wt%. More preferably, based on the total weight of the salt solvent melt, cryolite comprises 50–60 wt%, sodium chloride 20–30 wt%, and potassium chloride 15–20 wt%.

[0057] The total volume of rare earth oxide and carbon-containing alumina powder can be 10-40% of the volume of the salt solvent melt, preferably 15-35%, and more preferably 20-30%.

[0058] A salt solvent melt was prepared by reacting cryolite, sodium chloride, and potassium chloride. Rare earth oxides and carbon-containing alumina powder were then added to the salt solvent melt and mixed. After cooling, the precursor was obtained. Aluminum citrate (C6H5AlO7) was prepared under a vacuum of 10... -2 Alumina powder containing carbon is formed by calcination at Pa. The calcination temperature can be 700-900℃, preferably 750-850℃, and more preferably 800-820℃.

[0059] Preparation of alloy solution

[0060] Aluminum ingots are formed into aluminum melt; potassium fluorotitanate is added to the aluminum melt in batches and stirred, then the obtained precursor is added, and the reaction is continued to be stirred until complete. The salt solvent melt is removed to obtain an alloy solution.

[0061] After adding the precursor, continue stirring at 850–950°C for 20–60 minutes until the reaction is complete.

[0062] Preparation of grain refiner

[0063] The alloy solution is sequentially refined, degassed, and slag-removed to obtain a slag-removed alloy solution; the slag-removed alloy solution is further processed to obtain a grain refiner.

[0064] Refining, degassing, and slag removal can be performed using methods known in the field.

[0065] In some embodiments, the alloy solution after slag removal can be cast into ingots to obtain a grain refiner.

[0066] In other embodiments, the alloy solution after slag removal can be cast into a rod and then extruded into a thin rod to obtain a grain refiner. The extrusion temperature can be 300–500°C, preferably 350–450°C, and more preferably 380–400°C. The extrusion speed can be 15–30 mm / min, preferably 20–28 mm / min, and more preferably 20–25 mm / min.

[0067] <Preparation Methods of Aluminum Materials>

[0068] The present invention also provides a method for preparing aluminum material, comprising the following steps:

[0069] Aluminum raw materials are melted to obtain aluminum melt; the above-mentioned grain refiner is added to the aluminum melt and mixed to obtain molten metal; the molten metal is refined, degassed, and slag is removed, then cooled, and then solidified to obtain refined aluminum material.

[0070] In this invention, the amount of grain refiner added can be 0.05 to 0.5% of the mass of the aluminum melt; preferably, the amount of grain refiner added is 0.10 to 0.3% of the mass of the aluminum melt; more preferably, the amount of grain refiner added is 0.10 to 0.3% of the mass of the aluminum melt.

[0071] <Aluminum Materials>

[0072] The aluminum material of the present invention is prepared by the method described above. The size of the aluminum material prepared by the method of the present invention can reach below 90 μm.

[0073] <Application>

[0074] The present invention also provides the use of the above-mentioned grain refiner in refining the grain size of aluminum.

[0075] <Analytical Methods>

[0076] Elemental analysis: Analyzed using a Shimadzu ICPS-8100 inductively coupled plasma optical generator (ICPS).

[0077] SEM analysis: Microstructure analysis was performed using a Zeiss SIGMA500 microscope from Germany;

[0078] XRD analysis: Phase composition analysis was performed using a Bruker AXSD8 X-ray diffractometer manufactured by Bruker GmbH, Germany.

[0079] Metallographic analysis: The microstructure was observed and analyzed using a Zeiss Axio Imager 2 metallographic microscope;

[0080] Grain size measurement: Grain size was measured using the metallographic image analysis software AON-STUDIO according to the standard for average grain size of metals (GB / T 6394-2017) - intercept method.

[0081] Example 1

[0082] The chemical composition of the target product, the grain refiner, is: 95.9Al-3.5Ti-0.1C-0.5La. The preparation steps are as follows:

[0083] The raw materials are prepared according to the composition of the grain refiner. The raw materials include aluminum ingots, potassium fluorotitanate, lanthanum oxide, aluminum citrate, cryolite, sodium chloride, and potassium chloride. The actual addition amount of potassium fluorotitanate is 1.2 times the theoretical required amount of the target component; the actual addition amounts of lanthanum oxide and aluminum citrate are 1.1 and 1.15 times the theoretical required amounts of the target components, respectively; and the actual addition amount of aluminum is 1.1 times the theoretical required amount of the target component.

[0084] Aluminum citrate (C6H5AlO7) was placed in a quartz container and subjected to a vacuum of 10... -2 Alumina powder containing carbon was formed by heating at 10℃ / min to 800℃ and holding for 30 min. Cryolite, sodium chloride, and potassium chloride were placed in a graphite crucible and heated to prepare a salt solvent melt. Based on the total weight of the salt solvent melt, cryolite accounted for 60 wt%, sodium chloride for 25 wt%, and potassium chloride for 15 wt%. The total volume of lanthanum oxide and carbon-containing alumina powder was 20% of the volume of the salt solvent melt.

[0085] Lanthanum oxide and carbon-containing alumina powder were added to a salt solvent melt and stirred to form a liquid-solid mixture. The liquid-solid mixture was then cooled to obtain the precursor.

[0086] Aluminum ingots are formed into aluminum melt, and the temperature of the aluminum melt is controlled at 900℃. Dry potassium fluorotitanate wrapped in aluminum foil is added to the aluminum melt in batches and stirred. After the potassium fluorotitanate is completely melted, the precursor is added. After the precursor is completely melted, the reaction is continued with stirring to remove the salt solvent melt, and an alloy solution is obtained.

[0087] The alloy solution was successively refined, degassed, and slag removed, and then cooled to 730°C and cast into ingots to obtain a product grain refiner.

[0088] Example 2

[0089] The chemical composition of the target product grain refiner is: 95.85Al-3Ti-0.15C-1LaCe.

[0090] The preparation steps are as follows:

[0091] The raw materials are prepared according to the composition of the grain refiner. The raw materials include aluminum ingots, potassium fluorotitanate, lanthanum oxide, cerium oxide, aluminum citrate, cryolite, sodium chloride, and potassium chloride. The actual addition amount of potassium fluorotitanate is 1.2 times the theoretical required amount of the target component; the actual addition amounts of lanthanum oxide, cerium oxide, and aluminum citrate are 1.2, 1.2, and 1.15 times the theoretical required amounts of the target component, respectively; and the actual addition amount of aluminum is 1.1 times the theoretical required amount of the target component.

[0092] Aluminum citrate (C6H5AlO7) was placed in a quartz container and subjected to a vacuum of 10...-2 Alumina powder containing carbon was formed by heating at 10℃ / min to 800℃ and holding for 30 min. Cryolite, sodium chloride, and potassium chloride were placed in a graphite crucible and heated to prepare a salt solvent melt. Based on the total weight of the salt solvent melt, cryolite accounted for 60 wt%, sodium chloride for 25 wt%, and potassium chloride for 15 wt%. The total volume of lanthanum oxide, cerium oxide, and carbon-containing alumina powder was 20% of the volume of the salt solvent melt.

[0093] Lanthanum oxide, cerium oxide, and carbon-containing alumina powder were added to a salt solvent melt and stirred to form a liquid-solid mixture. The liquid-solid mixture was then cooled to obtain the precursor.

[0094] Aluminum ingots are formed into aluminum melt, and the temperature of the aluminum melt is controlled at 900℃. Dry potassium fluorotitanate wrapped in aluminum foil is added to the aluminum melt in batches and stirred. After the potassium fluorotitanate is completely melted, the precursor is added. After the precursor is completely melted, the reaction is continued with stirring to remove the salt solvent melt, and an alloy solution is obtained.

[0095] The alloy solution was successively refined, degassed, and slag removed, and then cooled to 730°C and cast into ingots to obtain a product grain refiner.

[0096] Example 3

[0097] The chemical composition of the target product grain refiner is: 94Al-5Ti-0.5C-0.5Ce. The preparation steps are as follows:

[0098] The raw materials are prepared according to the composition of the grain refiner. The raw materials include aluminum ingots, potassium fluorotitanate, cerium oxide, aluminum citrate, cryolite, sodium chloride, and potassium chloride. The actual addition amount of potassium fluorotitanate is 1.1 times the theoretical required amount of the target component; the actual addition amounts of cerium oxide and aluminum citrate are 1.15 and 1.2 times the theoretical required amounts of the target components, respectively; and the actual addition amount of aluminum is 1.1 times the theoretical required amount of the target component.

[0099] Aluminum citrate (C6H5AlO7) was placed in a quartz container and subjected to a vacuum of 10... -2 Alumina powder containing carbon was formed by heating at 10℃ / min to 800℃ and holding for 30 min. Cryolite, sodium chloride, and potassium chloride were placed in a graphite crucible and heated to prepare a salt solvent melt. Based on the total weight of the salt solvent melt, cryolite accounted for 60 wt%, sodium chloride for 25 wt%, and potassium chloride for 15 wt%. The total volume of cerium oxide and carbon-containing alumina powder was 20% of the volume of the salt solvent melt.

[0100] Cerium oxide and carbon-containing alumina powder are added to a salt solvent melt and stirred to form a liquid-solid mixture. The liquid-solid mixture is then cooled to obtain the precursor.

[0101] Aluminum ingots are formed into aluminum melt, and the temperature of the aluminum melt is controlled at 900℃. Dry potassium fluorotitanate wrapped in aluminum foil is added to the aluminum melt in batches and stirred. After the potassium fluorotitanate is completely melted, the precursor is added. After the precursor is completely melted, the reaction is continued with stirring to remove the salt solvent melt, and an alloy solution is obtained.

[0102] The alloy solution was sequentially refined, degassed, and slag removed, then cooled to 730℃ and cast into a rod. The rod was then hot-extruded into a thin rod with a diameter of 9.5 mm; the extrusion temperature was 400℃ and the extrusion speed was 20 mm / min, yielding a grain refiner.

[0103] The chemical composition of the grain refiners obtained in Examples 1-3 was analyzed using inductively coupled plasma atomic emission spectrometry (ICP). The results are shown in Table 1.

[0104] Table 1

[0105]

[0106] The XRD patterns of Examples 1 and 3 are shown in the figure. Figure 1 .from Figure 1 It can be seen that the Al-Ti-C-RE alloy mainly consists of α-Al, TiC phase, TiAl3 phase, and Ti2Al phase. 20 RE phase composition.

[0107] The morphology of Example 2 is shown in Figure 2. As can be seen from Figure 2, the TiC particles in the Al-Ti-C-LaCe master alloy are relatively small, approximately 200 nm in size.

[0108] The SEM scan image of Example 3 is shown below. Figure 3 .from Figure 3 As can be seen from the microstructure of the Al-Ti-C-RE alloy prepared in Example 3, there are gray blocky TiAl3 phases and bright white Ti2Al phases. 20 RE phases, with an average size of less than 5 μm, and finely dispersed TiC phases, with an average size of less than 0.5 μm.

[0109] Comparative Example 1

[0110] The chemical composition of the grain refiner in this comparative example is: 95.4Al-4.0Ti-0.5B-0.1C.

[0111] The preparation steps are as follows:

[0112] The raw materials are prepared according to the composition of the grain refiner. The raw materials include aluminum ingots, potassium fluorotitanate, potassium fluoroborate, aluminum citrate, cryolite, sodium chloride, and potassium chloride. The actual addition amounts of potassium fluorotitanate and potassium fluoroborate are 1.2 times the theoretically required amount of the target components, the actual addition amounts of aluminum citrate are 1.1 times the theoretically required amount of the target components, and the actual addition amount of aluminum is 1.1 times the theoretically required amount of the target components.

[0113] Aluminum citrate (C6H5AlO7) was placed in a quartz container and subjected to a vacuum of 10... -2 Alumina containing carbon is heated to 800℃ at 10℃ / min and held for 30min to form alumina powder containing carbon. Cryolite, sodium chloride, and potassium chloride are placed in a graphite crucible and heated to prepare a salt solvent melt. Based on the total weight of the salt solvent melt, cryolite is 60wt%, sodium chloride is 25wt%, and potassium chloride is 15wt%. The total volume of the carbon-containing alumina powder is 20% of the volume of the salt solvent melt.

[0114] Carbon-containing alumina powder is added to a salt solvent melt and stirred to form a liquid-solid mixture. The liquid-solid mixture is then cooled to obtain the precursor.

[0115] Aluminum ingots are formed into aluminum melt, and the temperature of the aluminum melt is controlled at 900℃. A mixed salt of potassium fluorotitanate and potassium fluoroborate, wrapped in aluminum foil and mixed evenly and dried, is added to the aluminum melt in batches and stirred. After the potassium fluorotitanate and potassium fluoroborate mixed salt are completely melted, the precursor is added. After the precursor is completely melted, the reaction is continued to be stirred to remove the salt solvent from the melt, and an alloy solution is obtained.

[0116] The alloy solution was successively refined, degassed, and slag removed, and then cooled to 730°C and cast into ingots to obtain a product grain refiner.

[0117] Example 4

[0118] Aluminum raw materials are melted to obtain aluminum melt; the grain refiner prepared in Example 1 is added to the aluminum melt and mixed evenly to obtain molten metal; a refining agent is added to the molten metal, and argon gas is simultaneously introduced into the molten metal for degassing using a degasser for 5 minutes. Slag is removed, and then the temperature is lowered to 720°C for solidification and shaping to obtain refined aluminum (also referred to as aluminum material). The mass of the grain refiner added is 0.1% of the mass of the aluminum melt.

[0119] Example 5

[0120] The difference from Example 4 is that the grain refiner prepared in Example 2 is used.

[0121] Example 6

[0122] The difference from Example 4 is that the grain refiner prepared in Example 3 is used.

[0123] Comparative Example 2

[0124] The difference from Example 4 is that the grain refiner prepared in Comparative Example 1 was used.

[0125] Metallographic structure testing and grain size measurement were performed on the aluminum raw material and the refined aluminum.

[0126] Metallographic images of aluminum raw materials and the refined aluminum obtained in Examples 4-6 and Comparative Example 2 are shown below. Figure 4 (A, B, C, D, E in sequence). The grain size of aluminum refined by the grain refiner obtained in the embodiments of this application is significantly reduced.

[0127] The grain size measurement results of the refined aluminum obtained from aluminum raw materials, Examples 4-6 and Comparative Example 2 are shown in Table 2.

[0128] Table 2

[0129] Grain size / μm 481.6 89.5 84.5 88.3 140.8

[0130] As shown in Table 2, the grain size of blank aluminum (i.e., unrefined aluminum raw material) reached 481.6 μm. However, the grain size of aluminum refined using the grain refiner of this invention can be reduced to below 90 μm. While the grain size of aluminum refined with the grain refiner in Comparative Example 2 showed some refining effect, the effect was not as good as that of the grain refiner of this invention.

[0131] This invention is not limited to the above-described embodiments. Any modifications, improvements, or substitutions that can be conceived by those skilled in the art without departing from the essential content of this invention fall within the scope of this invention.

Claims

1. A method for preparing a grain refiner, characterized in that, Includes the following steps: (1) Place cryolite, sodium chloride and potassium chloride in a graphite crucible and heat to prepare a salt solvent melt; (2) adding rare earth oxide and carbon-containing alumina powder into a salt solvent melt, stirring to uniformly disperse the rare earth oxide and carbon-containing alumina powder, to form a liquid-solid mixture; pouring the liquid-solid mixture into a graphite crucible to cool, to obtain a precursor; the total volume of the rare earth oxide and carbon-containing alumina powder is 10-40% of the volume of the salt solvent melt; the rare earth oxide is lanthanum oxide and / or cerium oxide; wherein the carbon-containing alumina powder is formed by calcining aluminum citrate at a vacuum degree of 10 -2 Pa and a temperature of 700-900°C. (3) Form aluminum melt from aluminum ingots; add potassium fluorotitanate to the aluminum melt in batches and stir, then add the precursor obtained in step (2), continue stirring until the reaction is complete, remove the salt solvent melt, and obtain the alloy solution; (4) The alloy solution is successively refined, degassed and slag removed to obtain the alloy solution after slag removal. The alloy solution after slag removal is further processed to obtain a grain refiner. The grain refiner has the following chemical composition: Al, Ti, C, RE, and unavoidable impurities; wherein, based on the total weight of the grain refiner, the Ti content is 0.1–5.5 wt%, the C content is 0.01–1.0 wt%, the RE content is 0.01–1.0 wt%, and the Al content is 93–98 wt%; the RE is La and / or Ce.

2. The preparation method according to claim 1, characterized in that, The chemical composition of the grain refiner is Al, Ti, C, La and unavoidable impurities; wherein, based on the total weight of the grain refiner, the Ti content is 1.0 to 5.0 wt%, the C content is 0.05 to 0.5 wt%, the La content is 0.1 to 0.5 wt%, and the Al content is 94 to 97 wt%.

3. The preparation method according to claim 1, characterized in that, The chemical composition of the grain refiner is Al, Ti, C, Ce and unavoidable impurities; wherein, based on the total weight of the grain refiner, the Ti content is 1.0 to 5.0 wt%, the C content is 0.3 to 0.5 wt%, the Ce content is 0.1 to 0.5 wt%, and the Al content is 94 to 97 wt%.

4. The preparation method according to claim 1, characterized in that, The grain refiner has the following chemical composition: Al, Ti, C, RE, and unavoidable impurities; wherein, based on the total weight of the grain refiner, the Ti content is 1.0–5.0 wt%, the C content is 0.05–0.5 wt%, the RE content is 0.5–1.0 wt%, and the Al content is 95–97 wt%; the RE is La and Ce; and the mass ratio of La to Ce is 1:1–3.

5. The preparation method according to any one of claims 1 to 4, characterized in that, The alloy nucleation phases of the grain refiner include TiAl3 phase, TiC phase, and Ti2Al phase. 20 One or more of the RE phases, with the matrix phase being the α-Al phase; The size of the TiAl3 phase is less than or equal to 5 μm; Ti2Al 20 The size of the RE phase is less than or equal to 5 μm; the size of the TiC phase is less than or equal to 1 μm.

6. A method for preparing an aluminum material, characterized in that, Includes the following steps: Aluminum raw material is melted to obtain a melt; a grain refiner obtained by the preparation method according to any one of claims 1 to 5 is added to the melt and mixed to obtain a molten metal; the molten metal is refined, degassed, and slag is removed, then cooled, and then solidified and formed to obtain aluminum material; The amount of the grain refiner added is 0.05 to 0.5% of the melt mass.

7. An aluminum material, characterized in that, It is prepared by the preparation method described in claim 6.

8. The use of a grain refiner obtained by the preparation method according to any one of claims 1 to 5 in refining the grain size of aluminum.

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