Grain refiner, aluminum material, preparation method and application

Abstract

The invention discloses a grain refiner, an aluminum material, a preparation method and application. The chemical components of the grain refiner comprise Al, Ti, C and RE; wherein based on the total weight of the grain refiner, the content of Ti is 0.1 wt%-5.5 wt%, the content of C is 0.01 wt%-1.0 wt%, the content of RE is 0.01 wt%-1.0 wt%, and the content of Al is 93 wt%-98 wt%; rE is La and / or Ce. The grain refiner disclosed by the invention has the advantages of fine size of a refined phase, dispersed distribution and uniform components, and the grain size of refined aluminum can be reduced to be less than 90 microns.

Description

Technical Field

[0001] The invention relates to a grain refiner, an aluminum material, a preparation method and an application thereof. Background Art

[0002] Grain refinement of aluminum alloys can obtain dense alloy structures, reduce the tendency of hot cracking and segregation of castings, reduce porosity, and thus improve the comprehensive performance of the alloy. At present, the most commonly used and effective refinement method is to add grain refiners. Aluminum titanium carbon has the advantages of finer TiC refinement phase, uniform distribution and non-aggregation, and good coherence with Al. Its refinement effect is better than that of traditional aluminum titanium boron refiners, and it has received extensive attention and application. However, due to the poor wettability of C in Al, its preparation is very difficult. The preparation cost of aluminum titanium carbon grain refiners is high when they are prepared by strong stirring or high-temperature reaction, which limits the widespread application of aluminum titanium carbon grain refiners.

[0003] In recent years, researchers have devoted themselves to developing new refiners to solve the above problems. For example, CN1108277374A, CN102784905B, CN111363936A and CN114150173A respectively disclose the preparation methods of Al-Ti-CY, Al-Ti-C-Er, Al-Ti-C-La and Al-Ti-C-Sc grain refiners, wherein the carbon source is graphite powder or carbon powder. Since C and Al have poor wettability, C is difficult to penetrate, and the temperature is high, and the preparation cost is also high. CN100467635C discloses a preparation method of aluminum-titanium-carbon master alloy, which uses aluminum-carbon and aluminum-titanium alloy as raw materials, has a simple process, but high cost and large size of refined phase. CN112899512B discloses an aluminum-titanium-carbon alloy grain refiner and its preparation method, which uses nano-scale TiC as a carbon source, which is costly, and the wettability between the added TiC particles and Al is poor, making it difficult to ensure the uniform distribution of TiC in the Al melt. CN111996424B discloses a TCB-Al seed alloy, its manufacturing method and a heritable aluminum alloy, which uses Al-Al3BC intermediate alloy as a carbon source, first prepares the intermediate alloy by a powder metallurgy method, and then adds it to pure aluminum as a carbon source. However, this method has a long process, high cost, and is difficult to control the B-doped TiC. B The content.

[0004] CN108411139A discloses an Al-Ti-C-Sr composite grain refiner, alloy and preparation method thereof. The refiner of the present invention is prepared by melting a basic material and SrO powder; the main material comprises aluminum powder, titanium powder and graphite powder in a mass ratio of 5: (1.5-2.5): (0.8-1.2), and the mass of SrO powder is 0.5-6% of the main material. The present invention presses the powder into a cylindrical prefabricated block by mixing the SrO powder and the main material and mechanically ball milling for 2 hours; firstly melt the raw aluminum in a graphite crucible, press the prefabricated block into the aluminum liquid when the temperature is raised to 800°C, the mass of the prefabricated block is 0.1-0.4% of the raw aluminum, keep the temperature for 5-20 minutes, and pour it into a metal mold after slagging to obtain an Al-Ti-C-Sr alloy. Although the method can reduce the size of pure aluminum or aluminum alloy, no specific reference data is involved.

[0005] CN114606415A discloses a grain refiner for aluminum and aluminum alloys. The grain refiner for aluminum and aluminum alloys in the present 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%, and the rest is aluminum. The present invention simultaneously adds C, Ce and Nb elements, so that the obtained grain refiner has a good refining effect on aluminum grains, and can achieve the refinement of aluminum grains to less than 150μm. The grain size obtained in the 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, whose refined phase has a small size, dispersed distribution, and uniform composition, and which can reduce the grain size of the refined aluminum to below 90μm. 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 a carbon source, low cost, and is easier to enter into an aluminum solution. Another object of the present invention is to provide a method for preparing an aluminum material. Another object of the present invention is to provide an aluminum material. Still another object of the present invention is to provide a use of a grain refiner.

[0007] In one aspect, the present invention provides a grain refiner, 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 0.1-5.5wt%, the C content is 0.01-1.0wt%, the RE content is 0.01-1.0wt%, and the Al content is 93-98wt%; 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 inevitable impurities; wherein,

[0010] Based on the total weight of the grain refiner, the Ti content is 0.1-5.5wt%, the C content is 0.01-1.0wt%, the RE content is 0.01-1.0wt%, 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 inevitable impurities; wherein,

[0012] 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 Al 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 inevitable impurities; wherein,

[0014] Based on the total weight of the grain refiner, the Ti content is 1.0-5.0wt%, the C content is 0.3-0.5wt%, the Ce content is 0.1-0.5wt%, 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 inevitable impurities; wherein,

[0016] Based on the total weight of the grain refiner, the Ti content is 1.0-5.0wt%, the C content is 0.05-0.5wt%, the RE content is 0.5-1.0wt%, 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 particle phase of the grain refiner includes TiAl3 phase, TiC phase and Ti2Al 20 One or more RE phases, the matrix phase is α-Al phase;

[0018] The size of TiAl3 phase is less than or equal to 5μm; 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 as described above, comprising the following steps:

[0020] (1) placing cryolite, sodium chloride and potassium chloride in a graphite crucible and heating them to form a salt solvent melt;

[0021] (2) adding rare earth oxide and carbon-containing alumina powder to a salt solvent melt, stirring to uniformly disperse the rare earth oxide and carbon-containing alumina powder to prepare a liquid-solid mixture; pouring the liquid-solid mixture into a graphite crucible and cooling it to obtain a precursor; the total volume of the rare earth oxide and carbon-containing alumina powder is 10 to 40% of the volume of the salt solvent melt; the rare earth oxide is lanthanum oxide and / or cerium oxide;

[0022] (3) forming an aluminum melt from an aluminum ingot; adding potassium fluorotitanate to the aluminum melt in batches and stirring, then adding the precursor obtained in step (2), continuing to stir until the reaction is complete, removing the salt solvent melt, and obtaining an alloy solution;

[0023] (4) The alloy solution is refined, degassed and deslagging in sequence to obtain a deslagging alloy solution, and the deslagging alloy solution is further treated to obtain a grain refiner.

[0024] In another aspect, the present invention further provides a method for preparing an aluminum material, comprising the following steps:

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

[0026] Wherein, the addition amount of the grain refiner is 0.05-0.5% of the melt mass.

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

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

[0029] The grain refiner of the present invention has a fine size, dispersed distribution and uniform composition. The preparation method of the grain refiner of the present invention has a high yield of effective elements, has a better refining effect than the grain refiner prepared by the prior art process, has a simple preparation process and a lower preparation cost. The preparation method of the present invention is to generate TiC phase, TiAl3 phase and Ti2Al 20 The RE phase method uses calcined aluminum citrate as a carbon source, so that carbon is more easily incorporated into the aluminum liquid and has a lower cost. The grain refiner prepared by the present invention has an increased number density of effective nucleation particles, and an improved refinement efficiency. Compared with the existing Al-Ti-C refiner, a smaller amount of refiner can be used to obtain the same refinement effect, thereby further reducing the use cost of the grain refiner. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] Figure 1 The XRD results of the grain refiners obtained in Examples 1 and 3 of the present invention are shown.

[0031] FIG2 is a morphology diagram of the grain refiner obtained in Example 2 of the present invention. Figure 2a It is the microstructure diagram of TiC phase; Figure 2b is the element distribution diagram of TiC phase; Figure 2c for Figure 2b A partial enlarged view of .

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

[0033] Figure 4 The metallographic structure diagrams of the aluminum raw material, the refined aluminum obtained in Example 4, Example 5, Example 6 and Comparative Example 2 are measured. DETAILED DESCRIPTION

[0034] The present invention is further described below in conjunction with specific embodiments, but the protection scope of the present invention is not limited thereto.

[0035] <Grain refiner>

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

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

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

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

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

[0041] The Al content may be 93 to 98 wt %, preferably 94 to 97 wt %, and more preferably 95 to 97 wt %, based on the total weight of the grain refiner.

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

[0043] 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 Al is the balance.

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

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

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

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

[0048] The present invention unexpectedly found that the grain refiner prepared by using the Al-Ti-C-RE system and the preparation method of the present invention can better refine the aluminum material and obtain finer grains. The present invention believes that this is because rare earth atoms, especially La or Ce, contribute to the refinement and uniform distribution of TiC and TiAl3 phases. In addition, La or Ce atoms have the function of degassing and removing impurities in aluminum, and the REAl phase formed by rare earth and Al can act as a particle for heterogeneous nucleation, which plays a role in refining grains, thereby improving the quality of the alloy and the grain refining effect.

[0049] The alloy nucleation particle phase of the grain refiner of the present invention includes TiAl3 phase, TiC phase and Ti2Al 20 One or more of the RE phases, the matrix phase is an α-Al phase; preferably, the alloy nucleation particle phase of the grain refiner of the present invention is composed of TiAl3 phase, TiC phase and Ti2Al20 Various compositions in RE phase.

[0050] The size of TiAl3 phase is less than or equal to 5 μm, preferably less than or equal to 3 μm; 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] <Method for preparing grain refiner>

[0052] The method for preparing the grain refiner of the present invention comprises the following steps: (1) preparing a precursor; (2) preparing an alloy solution; and (3) preparing a grain refiner.

[0053] The prior art usually directly sintered aluminum ingots, carbon powder / graphite powder and titanium powder raw materials to form alloy ingots, or directly formed a melt of aluminum ingots, carbon powder / graphite powder and potassium fluorotitanate raw materials and then cast them into alloys. The present invention forms carbon-containing alumina powder as a carbon source by vacuum calcining aluminum citrate. 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, and then the aluminum ingot is formed into a melt. Potassium fluorotitanate and rare earth-containing precursors and carbon-containing alumina powder are added to the melt of the aluminum ingot, and the salt solvent melt is removed to obtain an alloy solution. The method of the present invention is conducive to the dispersion of rare earth and carbon atoms, improves the efficiency of the reaction, and is conducive to preventing the precipitation of refined phases. The present invention believes that the present invention first uses a fluoride salt reaction to reduce Ti atoms from potassium fluorotitanate, and then performs an aluminothermic reduction method to reduce the rare earth atoms in the rare earth oxide. The Ti atoms in the reaction solution successively react with C atoms and Al atoms to form fine TiC and TiAl3 phases and Ti2Al 20 RE phase, thereby improving the refinement effect of the refined phase TiC and TiAl3 phase. In addition, rare earth atoms will prevent the aggregation and growth of the refined phase, and the excess atoms will play a role in degassing, removing impurities and refining the aluminum material, thereby improving the quality of the aluminum material.

[0054] Preparation of precursors

[0055] The present invention uses cryolite, sodium chloride and potassium chloride to form a salt solvent melt, and uses the salt solvent melt as a solvent to form a precursor containing rare earth and carbon. This is beneficial to the dispersion of rare earth and carbon, improves the efficiency of the reaction, and helps prevent the precipitation of refined phases.

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

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

[0058] Cryolite, sodium chloride and potassium chloride are made into a salt solvent melt, and rare earth oxides and carbon-containing aluminum oxide powder are added to the salt solvent melt, mixed, and cooled to obtain a precursor. Among them, aluminum citrate (C6H5AlO7) can be heated to 10°C in a vacuum. -2 The aluminum oxide powder containing C is calcined at 400° C. to form the aluminum oxide powder. The calcination temperature may be 700 to 900° C., preferably 750 to 850° C., and more preferably 800 to 820° C.

[0059] Preparation of alloy solution

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

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

[0062] Preparation of grain refiner

[0063] The alloy solution is refined, degassed and deslagging in sequence to obtain a deslagging alloy solution; the deslagging alloy solution is further processed to obtain a grain refiner.

[0064] The refining, degassing and slagging processes known in the art may be adopted.

[0065] In certain embodiments, the alloy solution after slagging can be cast into an ingot to obtain a grain refiner.

[0066] In other embodiments, the alloy solution after slagging can be cast into a cast 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] <Method for preparing aluminum material>

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

[0069] The aluminum raw material is melted to obtain an aluminum melt; the grain refiner is added to the aluminum melt to obtain a molten metal; the molten metal is refined, degassed, and slag-removed, then cooled, and then solidified and formed to obtain a refined aluminum material.

[0070] In the present invention, the grain refiner may be added in an amount of 0.05-0.5% of the mass of the aluminum melt; preferably, the grain refiner is added in an amount of 0.10-0.3% of the mass of the aluminum melt; more preferably, the grain refiner is added in an amount of 0.10-0.3% of the mass of the aluminum melt.

[0071] <Aluminum Material>

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

[0073] <Purpose>

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

[0075] <Analysis Method>

[0076] Elemental analysis: Analyzed using Japan Shimadzu ICPS-8100 inductively coupled plasma spectrometer;

[0077] SEM analysis: German Zeiss SIGMA500 was used for microstructure analysis;

[0078] XRD analysis: The phase composition analysis was performed using a Bruker AXSD8 X-ray diffractometer produced by Bruker, Germany;

[0079] Metallographic structure analysis: Zeiss metallographic microscope Axio Imager 2 was used for structure observation and analysis;

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

[0081] Example 1

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

[0083] Prepare raw materials according to the composition of grain refiner. The raw materials include aluminum ingot, 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 amount required for the target composition, the actual addition amount of lanthanum oxide and aluminum citrate is 1.1 and 1.15 times the theoretical amount required for the target composition respectively, and the actual addition amount of aluminum is 1.1 times the theoretical amount required for the target composition.

[0084] Aluminum citrate (C6H5AlO7) was placed in a quartz container and vacuumed to 10 -2 Pa and heated to 800°C at 10°C / min, and kept warm for 30 minutes to form C-containing alumina powder; cryolite, sodium chloride and potassium chloride are placed in a graphite crucible and heated to form a salt solvent melt; wherein, 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 lanthanum oxide and carbon-containing alumina powder is 20% of the volume of the salt solvent melt.

[0085] Lanthanum oxide and carbon-containing aluminum oxide powder are added to a salt solvent melt, stirred and mixed to form a liquid-solid mixture, and the liquid-solid mixture is cooled to obtain a precursor.

[0086] The aluminum ingot is formed into an aluminum melt, and the temperature of the aluminum melt is controlled at 900° C. The dried 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 stirring reaction is continued to remove the salt solvent melt to obtain an alloy solution.

[0087] The alloy solution is refined, degassed and deslagging in sequence, 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] Prepare raw materials according to the composition of grain refiner. The raw materials include aluminum ingot, 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 amount required for the target component, the actual addition amount of lanthanum oxide, cerium oxide and aluminum citrate is 1.2, 1.2 and 1.15 times the theoretical amount required for the target component respectively, and the actual addition amount of aluminum is 1.1 times the theoretical amount required for the target component.

[0092] Aluminum citrate (C6H5AlO7) was placed in a quartz container and vacuumed to 10-2 Pa and heated to 800°C at 10°C / min, and kept warm for 30 minutes to form C-containing alumina powder; cryolite, sodium chloride and potassium chloride are placed in a graphite crucible and heated to form a salt solvent melt; wherein, 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 lanthanum oxide, cerium oxide and carbon-containing alumina powder is 20% of the volume of the salt solvent melt.

[0093] Lanthanum oxide, cerium oxide and carbon-containing aluminum oxide powder are added into a salt solvent melt, stirred and mixed to form a liquid-solid mixture, and the liquid-solid mixture is cooled to obtain a precursor.

[0094] The aluminum ingot is formed into an aluminum melt, and the temperature of the aluminum melt is controlled at 900° C. The dried 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 stirring reaction is continued to remove the salt solvent melt to obtain an alloy solution.

[0095] The alloy solution is refined, degassed and deslagging in sequence, 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] Prepare raw materials according to the composition of grain refiner. The raw materials include aluminum ingot, 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 amount required for the target component, the actual addition amount of cerium oxide and aluminum citrate is 1.15 and 1.2 times the theoretical amount required for the target component respectively, and the actual addition amount of aluminum is 1.1 times the theoretical amount required for the target component.

[0099] Aluminum citrate (C6H5AlO7) was placed in a quartz container and vacuumed to 10 -2 Pa and heated to 800°C at 10°C / min, and kept warm for 30 minutes to form C-containing alumina powder; cryolite, sodium chloride and potassium chloride are placed in a graphite crucible and heated to form a salt solvent melt; wherein, 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 cerium oxide and carbon-containing alumina powder is 20% of the volume of the salt solvent melt.

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

[0101] The aluminum ingot is formed into an aluminum melt, and the temperature of the aluminum melt is controlled at 900° C. The dried 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 stirring reaction is continued to remove the salt solvent melt to obtain an alloy solution.

[0102] The alloy solution is refined, degassed, and slag-stripped in sequence, and then cooled to 730°C and cast into a cast rod. The cast rod is hot-extruded into a thin rod with a diameter of 9.5 mm; wherein the extrusion temperature is 400°C and the extrusion speed is 20 mm / min, and a product grain refiner is obtained.

[0103] The chemical composition of the grain refiners obtained in Examples 1 to 3 was detected and analyzed using an inductively coupled plasma spectrometer ICP. The detection results are shown in Table 1.

[0104] Table 1

[0105]

[0106] The XRD results of Example 1 and Example 3 are shown in Figure 1 .from Figure 1 It can be seen that the Al-Ti-C-RE alloy is mainly composed of α-Al, TiC phase, TiAl3 phase and Ti2Al 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, about 200 nm.

[0108] The SEM scanning electron microscope image of Example 3 is shown in Figure 3 .from Figure 3 It can be seen that the Al-Ti-C-RE alloy microstructure prepared in Example 3 contains gray blocky TiAl3 phase and bright white Ti2Al 20 The RE phase has an average size of less than 5 μm, and the finely dispersed TiC phase has an average size of less than 0.5 μm.

[0109] Comparative Example 1

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

[0111] The preparation steps are as follows:

[0112] Prepare raw materials according to the composition of grain refiner. The raw materials include aluminum ingot, potassium fluorotitanate, potassium fluoroborate, aluminum citrate, cryolite, sodium chloride and potassium chloride. The actual addition amount of potassium fluorotitanate and potassium fluoroborate is 1.2 times the theoretical amount required for the target composition, the actual addition amount of aluminum citrate is 1.1 times the theoretical amount required for the target composition, and the actual addition amount of aluminum is 1.1 times the theoretical amount required for the target composition.

[0113] Aluminum citrate (C6H5AlO7) was placed in a quartz container and vacuumed to 10 -2 Pa and heated to 800°C at 10°C / min, and kept warm for 30 minutes to form C-containing alumina powder; cryolite, sodium chloride and potassium chloride are placed in a graphite crucible and heated to form a salt solvent melt; wherein, 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] The carbon-containing aluminum oxide powder is added into the salt solvent melt, stirred and mixed to form a liquid-solid mixture, and the liquid-solid mixture is cooled to obtain a precursor.

[0115] The aluminum ingot is formed into an aluminum melt, and the temperature of the aluminum melt is controlled at 900° C. Aluminum foil wrapped, evenly mixed, and dried potassium fluorotitanate and potassium fluoroborate mixed salts are added to the aluminum melt in batches and stirred. After the potassium fluorotitanate and potassium fluoroborate mixed salts are completely melted, the precursor is added. After the precursor is completely melted, the stirring reaction is continued to remove the salt solvent melt to obtain an alloy solution.

[0116] The alloy solution is refined, degassed and deslagging in sequence, then cooled to 730°C and cast into ingots to obtain a product grain refiner.

[0117] Example 4

[0118] The aluminum raw material is melted to obtain an aluminum melt; the grain refiner prepared in Example 1 is added to the aluminum melt and mixed evenly to obtain a metal melt; a refining agent is added to the metal melt, and argon gas is introduced into the metal melt for degassing for 5 minutes by a degasser, and then the slag is removed, and then the temperature is lowered to 720°C, and solidification molding is performed 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 is used.

[0125] The aluminum raw material and the refined aluminum were subjected to metallographic structure testing and grain size measurement.

[0126] The metallographic structure diagrams of the aluminum raw material and the refined aluminum obtained in Examples 4 to 6 and Comparative Example 2 are shown in Figure 4 (a, b, c, d, e in order) The grain size of aluminum after being refined by the grain refiner obtained in the example of the present application is significantly reduced.

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

[0128] Table 2

[0129] Refining agent Aluminum raw materials Example 4 Example 5 Example 6 Comparative Example 2 Grain size / μm 481.6 89.5 84.5 88.3 140.8

[0130] As can be seen from Table 2, the grain size of blank aluminum (i.e., unrefined aluminum raw material) is 481.6 μm. However, the grain size of aluminum after being refined by the grain refiner of the present invention can be reduced to below 90 μm. Although the grain size of aluminum after being refined by the grain refiner of Comparative Example 2 has a certain refining effect, the effect is not as good as that of the grain refiner of the present invention.

[0131] The present invention is not limited to the above-mentioned embodiments. Without departing from the essential content of the present invention, any deformation, improvement and substitution that can be conceived by those skilled in the art shall fall within the scope of the present invention.

Claims

1. A grain refiner, characterized in that: The chemical composition of the grain refiner includes Al, Ti, C and RE; wherein, Based on the total weight of the grain refiner, the Ti content is 0.1-5.5wt%, the C content is 0.01-1.0wt%, the RE content is 0.01-1.0wt%, and the Al content is 93-98wt%; the RE is La and / or Ce.

2. The grain refiner according to claim 1, characterized in that The chemical composition of the grain refiner is Al, Ti, C, RE and inevitable impurities; wherein, Based on the total weight of the grain refiner, the Ti content is 0.1-5.5wt%, the C content is 0.01-1.0wt%, the RE content is 0.01-1.0wt%, and Al is the balance; the RE is La and / or Ce.

3. The grain refiner according to claim 2, characterized in that The chemical composition of the grain refiner is Al, Ti, C, La and inevitable 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 Al is the balance.

4. The grain refiner according to claim 2, characterized in that The chemical composition of the grain refiner is Al, Ti, C, Ce and inevitable impurities; wherein, Based on the total weight of the grain refiner, the Ti content is 1.0-5.0wt%, the C content is 0.3-0.5wt%, the Ce content is 0.1-0.5wt%, and Al is the balance.

5. The grain refiner according to claim 2, characterized in that: The chemical composition of the grain refiner is Al, Ti, C, RE and inevitable impurities; wherein, Based on the total weight of the grain refiner, the Ti content is 1.0-5.0wt%, the C content is 0.05-0.5wt%, the RE content is 0.5-1.0wt%, and Al is the balance; the RE is La and Ce; the mass ratio of La to Ce is 1:1-3.

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

7. A method for preparing a grain refiner according to claim 1, characterized in that: The steps include: (1) placing cryolite, sodium chloride and potassium chloride in a graphite crucible and heating them to form a salt solvent melt; (2) adding rare earth oxide and carbon-containing alumina powder to a salt solvent melt, stirring to uniformly disperse the rare earth oxide and carbon-containing alumina powder to prepare a liquid-solid mixture; pouring the liquid-solid mixture into a graphite crucible and cooling it to obtain a precursor; the total volume of the rare earth oxide and carbon-containing alumina powder is 10 to 40% of the volume of the salt solvent melt; the rare earth oxide is lanthanum oxide and / or cerium oxide; (3) forming an aluminum melt from an aluminum ingot; adding potassium fluorotitanate to the aluminum melt in batches and stirring, then adding the precursor obtained in step (2), continuing to stir until the reaction is complete, removing the salt solvent melt, and obtaining an alloy solution; (4) The alloy solution is refined, degassed and deslagging is performed in sequence to obtain a deslagging alloy solution, and the deslagging alloy solution is further treated to obtain a grain refiner.

8. A method for preparing an aluminum material, characterized in that: The steps include: Melting the aluminum raw material to obtain a melt; adding the grain refiner according to any one of claims 1 to 6 to the melt and mixing to obtain a molten metal; refining, degassing and slagging the molten metal, then cooling it, and then performing a solidification and molding process to obtain an aluminum material; Wherein, the addition amount of the grain refiner is 0.05-0.5% of the melt mass.

9. An aluminum material, characterized in that: It is prepared by the preparation method described in claim 8.

10. Use of the grain refiner according to any one of claims 1 to 6 in refining the size of aluminum grains.

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