A method for preparing a homogenized aluminum-scandium master alloy

Abstract

The application discloses a preparation method of a homogenized aluminum-scandium intermediate alloy, and comprises the following steps: smelting: the scandium oxide, the molten salt and the aluminum ingot are heated to 1000-1200 DEG C, and then the temperature is kept at 900-1000 DEG C and stirred, the mass ratio of the scandium oxide, the molten salt and the aluminum ingot is 3.5-4.5:50-65:100; the aluminum-scandium intermediate alloy liquid is obtained through impurity removal and temperature keeping; the aluminum-scandium intermediate alloy is obtained through slagging, casting and cooling. Through process optimization, the aluminum-scandium intermediate alloy prepared by the preparation method has low segregation rate, uniform composition and low impurity content.

Description

Technical Field

[0001] The present invention relates to the technical field of aluminum alloys, and in particular to a method for preparing a homogenized aluminum-scandium master alloy. Background Art

[0002] Scandium is the most effective grain refiner in aluminum alloys. Practical applications have shown that Al-Sc alloys offer advantages such as light weight, high strength, high plasticity, high-temperature resistance, corrosion resistance, and excellent weldability. Consequently, this alloy family is finding increasing application in missiles, nuclear reactors, aerospace, aviation, shipbuilding, light vehicles, high-speed trains, sports equipment, and other high-tech applications. my country possesses abundant scandium resources and mature production technology capable of producing products such as Sc, ScCl₃, and Sc₂O₃, which serve as raw materials for Al-Sc alloys. This provides a material foundation and advantageous conditions for the future development of Al-Sc products.

[0003] In the current existing technology, the production of aluminum-scandium master alloy using metal scandium, scandium chloride or scandium oxide has the problem of scandium segregation, which has an adverse effect on the subsequent use of the aluminum-scandium master alloy. Summary of the Invention

[0004] In order to solve the segregation problem in producing aluminum-scandium master alloy using scandium oxide, the present invention provides a preparation method of a homogenized aluminum-scandium master alloy.

[0005] A method for preparing a homogenized aluminum-scandium master alloy, comprising:

[0006] Smelting: heating scandium oxide, molten salt and aluminum ingot to 1000-1200°C, then maintaining the temperature at 900-1000°C with stirring, wherein the mass ratio of scandium oxide, molten salt and aluminum ingot is 3.5-4.5:50-65:100;

[0007] After removing impurities and keeping warm, aluminum-scandium master alloy liquid is obtained;

[0008] The aluminum-scandium master alloy is obtained through deslagging, casting and cooling.

[0009] Furthermore, the smelting is carried out in a non-vacuum medium frequency furnace.

[0010] Furthermore, the heating is carried out at a constant speed of 10 to 20 kW / h.

[0011] Furthermore, the heat preservation and stirring time is 30 to 60 minutes.

[0012] Furthermore, the molten salt is scandium fluoride, potassium chloride, sodium fluoride, sodium chloride and cryolite, and the mass ratio is 1.5-2.5:8-10:5-6:9-11:30-32.

[0013] Furthermore, the mass ratio of scandium oxide, scandium fluoride, potassium chloride, sodium fluoride, sodium chloride, cryolite and aluminum ingot is 4:2:9:5.5:10:30:100.

[0014] Furthermore, the impurity removal is as follows: introducing argon gas with a purity greater than 99.99% and blowing argon for 10 to 20 minutes.

[0015] Furthermore, the heat preservation is carried out at 900-950° C. and 800-850° C. for 0.5-1 hour.

[0016] Furthermore, the casting temperature is 750-800°C.

[0017] Furthermore, the cooling is as follows: the water-cooled mold circulating water temperature is 5-15°C, and the flow rate is set to 0.5-1.5m 3 / h, cooling for 5 to 8 seconds.

[0018] The present invention provides a method for preparing a homogenized aluminum-scandium master alloy. Through process optimization, the obtained aluminum-scandium master alloy has low segregation rate, uniform composition and low impurity content. DETAILED DESCRIPTION

[0019] An embodiment of the present invention provides a method for preparing a homogenized aluminum-scandium master alloy, comprising:

[0020] Smelting: heating scandium oxide, molten salt and aluminum ingot to 1000-1200°C, then maintaining the temperature at 900-1000°C with stirring, wherein the mass ratio of scandium oxide, molten salt and aluminum ingot is 3.5-4.5:50-65:100;

[0021] After removing impurities and keeping warm, aluminum-scandium master alloy liquid is obtained;

[0022] The aluminum-scandium master alloy is obtained through deslagging, casting and cooling.

[0023] In an embodiment of the present invention, the present invention uses scandium oxide as raw material, and obtains an aluminum-scandium intermediate alloy with low component segregation rate, low impurity content, and scandium content of 2%±0.2 by controlling the ratio of reaction raw materials, smelting temperature, insulation and stirring during smelting, as well as impurity removal, insulation and slag removal, casting, and cooling.

[0024] Furthermore, the smelting is carried out in a non-vacuum medium frequency furnace.

[0025] In the existing technology, a combination of a resistance furnace and a holding furnace is generally used, which has refined functions and high costs. We use a non-vacuum medium-frequency furnace with a single function, which reduces equipment costs while achieving good homogenization of the aluminum-scandium master alloy. The scandium content of the prepared aluminum-scandium master alloy is 2%±0.2.

[0026] Furthermore, the heating is carried out at a constant speed of 10 to 20 kW / h.

[0027] In the embodiments of the present invention, a non-vacuum medium-frequency furnace is used for the smelting reaction. This non-vacuum medium-frequency furnace is simple and easy to operate. A controlled heating rate of 10 to 20 kW per hour facilitates the smelting reaction. Heating at rates below 10 kW per hour increases the viscosity of the molten salt, while heating at rates above 20 kW per hour accelerates its volatilization. Therefore, both rapid and slow heating rates are detrimental to the reaction. The present invention specifies a heating rate of 10 to 20 kW / h.

[0028] Furthermore, the heat preservation and stirring time is 30 to 60 minutes.

[0029] In the embodiment of the present invention, if the stirring time is less than 30 minutes, the molten salt reaction will be insufficient and the scandium yield will be low; if the stirring time exceeds 60 minutes, the molten salt volatilization will be accelerated. Experimental results show that a stirring time of 30 to 60 minutes is beneficial to the reaction of the aluminum-scandium master alloy.

[0030] Furthermore, the molten salt is scandium fluoride, potassium chloride, sodium fluoride, sodium chloride and cryolite, with a mass ratio of 1.5-2.5:8-10:5-6:9-11:30-32. Preferably, the mass ratio of scandium oxide, scandium fluoride, potassium chloride, sodium fluoride, sodium chloride, cryolite and aluminum ingot is 4:2:9:5.5:10:30:100.

[0031] In the embodiments of the present invention, through a large number of experiments, taking into account the production cost and the scandium yield, the ratio of the molten salt can meet the requirements of low production cost and high scandium yield.

[0032] Furthermore, the impurity removal is as follows: introducing argon gas with a purity greater than 99.99% and blowing argon for 10 to 20 minutes.

[0033] In an embodiment of the present invention, impurities are removed by blowing argon.

[0034] Furthermore, the heat preservation is carried out at 900-950° C. and 800-850° C. for 0.5-1 hour.

[0035] In the embodiments of the present invention, a heat preservation treatment can achieve a homogenization effect. The heat preservation treatment allows the Al3Sc particles to gradually diffuse into the aluminum-scandium alloy liquid, avoiding component segregation. Experiments have shown that a two-step heat preservation method, at 900-950°C and 800-850°C for 0.5-1 hour, respectively, achieves the best homogenization effect.

[0036] Furthermore, the casting temperature is 750-800°C.

[0037] In the embodiment of the present invention, when the casting temperature is 750-800° C., the obtained aluminum-scandium master alloy has good quality and low component segregation. A casting temperature below 750° C. will cause condensation of the alloy liquid and component segregation.

[0038] Furthermore, the cooling is as follows: the water-cooling mold circulating water temperature is 5-15°C, the flow rate is set to 0.5-1.5m3 / h, and the cooling is 5-8s.

[0039] In the embodiment of the present invention, the circulating water is used for rapid cooling, so that the fine dispersed Al3Sc particles are retained and prevented from growing and causing segregation.

[0040] In summary, the embodiment of the present invention utilizes the method of medium frequency furnace melting, homogenization treatment and rapid quenching casting to obtain an aluminum-scandium master alloy with low segregation rate, uniform composition and low impurity content, which can further reduce the production cost of the aluminum-scandium master alloy and achieve comprehensive utilization of resources.

[0041] Example 1 A method for preparing a homogenized aluminum-scandium master alloy

[0042] A method for preparing a homogenized aluminum-scandium master alloy, specifically comprising:

[0043] (1) Melting: Scandium oxide, molten salt and aluminum ingot are added to a non-vacuum medium frequency furnace, and the temperature is uniformly increased to 1100°C at a rate of 15 kW / h, and then kept at 950°C with stirring for 30 minutes. The molten salt is scandium fluoride, potassium chloride, sodium fluoride, sodium chloride and cryolite. The mass ratio of scandium oxide, scandium fluoride, potassium chloride, sodium fluoride, sodium chloride, cryolite and aluminum ingot is 4:2:9:5.5:10:31:100.

[0044] (2) Impurity removal: introduce argon gas with a purity greater than 99.99% and blow argon for 10 minutes.

[0045] (3) Insulation: Insulate at 925°C and 825°C for 30 min respectively.

[0046] (4) Slag removal and casting: After the insulation is completed, slag removal and casting are carried out, and the casting temperature is 800℃.

[0047] (5) Cooling: Set the temperature of the water-cooled mold circulating water to 10°C in advance and the flow rate to 0.8m 3 / h, the aluminum-scandium alloy liquid can be solidified and taken out in the water-cooled mold in 5 to 8 seconds.

[0048] (6) Sampling, analysis and testing of aluminum-scandium intermediate alloy.

[0049] Example 2 A method for preparing a homogenized aluminum-scandium master alloy

[0050] A method for preparing a homogenized aluminum-scandium master alloy, specifically comprising:

[0051] (1) Melting: Scandium oxide, molten salt and aluminum ingot are added to a non-vacuum medium frequency furnace, and the temperature is uniformly increased to 1000°C at a rate of 10 kW / h, and then kept at 900°C with stirring for 30 minutes. The molten salt is scandium fluoride, potassium chloride, sodium fluoride, sodium chloride and cryolite. The mass ratio of scandium oxide, scandium fluoride, potassium chloride, sodium fluoride, sodium chloride, cryolite and aluminum ingot is 3.5:2.5:8:5:9:32:100.

[0052] (2) Impurity removal: introduce argon gas with a purity greater than 99.99% and blow argon for 10 minutes.

[0053] (3) Insulation: Insulate at 900°C and 800°C for 60 minutes respectively.

[0054] (4) Slag removal and casting: After the insulation is completed, slag removal and casting are carried out, and the casting temperature is 800℃.

[0055] (5) Cooling: Set the temperature of the water-cooled mold circulating water to 5°C in advance and the flow rate to 0.5m 3 / h, the aluminum-scandium alloy liquid can be solidified and taken out in the water-cooled mold in 5 to 8 seconds.

[0056] (6) Sampling, analysis and testing of aluminum-scandium intermediate alloy.

[0057] Example 3: Preparation method of a homogenized aluminum-scandium master alloy

[0058] A method for preparing a homogenized aluminum-scandium master alloy, specifically comprising:

[0059] (1) Melting: Scandium oxide, molten salt and aluminum ingot are added to a non-vacuum medium frequency furnace, and the temperature is uniformly increased to 1200°C at a rate of 20 kW / h, and then kept at 1000°C with stirring for 30 minutes. The molten salt is scandium fluoride, potassium chloride, sodium fluoride, sodium chloride and cryolite. The mass ratio of scandium oxide, scandium fluoride, potassium chloride, sodium fluoride, sodium chloride, cryolite and aluminum ingot is 4.5:1.5:10:6:11:30:100.

[0060] (2) Impurity removal: introduce argon gas with a purity greater than 99.99% and blow argon for 20 minutes.

[0061] (3) Insulation: Insulate at 950°C and 850°C for 50 min respectively.

[0062] (4) Slag removal and casting: After the insulation is completed, slag removal and casting are carried out, and the casting temperature is 750℃.

[0063] (5) Cooling: Set the temperature of the water-cooled mold circulating water to 15°C in advance and the flow rate to 1.5m 3 / h, the aluminum-scandium alloy liquid can be solidified and taken out in the water-cooled mold in 5 to 8 seconds.

[0064] (6) Sampling, analysis and testing of aluminum-scandium intermediate alloy.

[0065] The results of the aluminum-scandium master alloys prepared in Examples 1-3 are shown in Table 1. As can be seen from Table 1, the aluminum-scandium master alloys prepared in Examples 1-3 have a scandium content of 2% ± 0.2 and low impurity content. Furthermore, the aluminum-scandium master alloy prepared in Example 1 was analyzed for scandium content at different locations. The results show that the aluminum-scandium master alloy prepared in Example 1 has good homogenization, with scandium content at different locations consistently within 2% ± 0.2.

[0066] Comparative Example 1: Preparation Method of Aluminum-Schanddium Master Alloy

[0067] A method for preparing an aluminum-scandium master alloy, specifically comprising:

[0068] (1) Melting: Scandium oxide, molten salt and aluminum ingot are added to a non-vacuum medium frequency furnace, and the temperature is uniformly increased to 1050°C at a rate of 15 kW / h, and then kept stirred at 950°C for 15 minutes. The molten salt is scandium fluoride, potassium chloride, sodium fluoride, sodium chloride and cryolite. The mass ratio of scandium oxide, scandium fluoride, potassium chloride, sodium fluoride, sodium chloride, cryolite and aluminum ingot is 4:2:9:5.5:10:30:100.

[0069] (2) Impurity removal: introduce argon gas with a purity greater than 99.99% and blow argon for 10 minutes.

[0070] (3) Insulation: Insulate at 925°C and 825°C for 30 min respectively.

[0071] (4) Slag removal and casting: After the insulation is completed, slag removal and casting are carried out, and the casting temperature is 800℃.

[0072] (5) Cooling: Set the temperature of the water-cooled mold circulating water to 10°C in advance and the flow rate to 0.8m 3 / h, the aluminum-scandium alloy liquid can be solidified and taken out in the water-cooled mold in 5 to 8 seconds.

[0073] (6) Sampling, analysis and testing of aluminum-scandium intermediate alloy.

[0074] The difference between Comparative Example 1 and Example 1 is that, in step (1) of Example 1, the smelting was performed with stirring at 950°C for 30 minutes, while in step (1) of Comparative Example 1, the smelting was performed with stirring at 950°C for 15 minutes. The stirring time is different. The results of the aluminum-scandium master alloy prepared in Comparative Example 1 are shown in Table 2. As can be seen from Table 2, the stirring time was insufficient, the scandium content of the aluminum-scandium master alloy was low, and the scandium content was unevenly distributed in various parts.

[0075] Comparative Example 2: Preparation Method of an Aluminum-Schanddium Master Alloy

[0076] A method for preparing an aluminum-scandium master alloy, specifically comprising:

[0077] (1) Melting: Scandium oxide, molten salt and aluminum ingot are added to a non-vacuum medium frequency furnace, and the temperature is uniformly increased to 1100°C at a rate of 15 kW / h, and then kept at 950°C with stirring for 30 minutes. The molten salt is scandium fluoride, potassium chloride, sodium fluoride, sodium chloride and cryolite. The mass ratio of scandium oxide, scandium fluoride, potassium chloride, sodium fluoride, sodium chloride, cryolite and aluminum ingot is 4:2:9:5.5:10:31:100.

[0078] (2) Impurity removal: introduce argon gas with a purity greater than 99.99% and blow argon for 10 minutes.

[0079] (3) Slag removal and casting: After the insulation is completed, slag removal and casting are carried out, and the casting temperature is 800℃.

[0080] (4) Cooling: Set the temperature of the water-cooled mold circulating water to 10°C in advance and the flow rate to 0.8m 3 / h, the aluminum-scandium alloy liquid can be solidified and taken out in the water-cooled mold in 5 to 8 seconds.

[0081] (5) Sampling, analysis and testing of aluminum-scandium intermediate alloy.

[0082] Comparative Example 2 differs from Example 1 in that Comparative Example 2 does not undergo the heat preservation treatment of step (3) of Example 1. The results of the aluminum-scandium master alloy prepared in Comparative Example 2 are shown in Table 2. As can be seen from Table 2, without the homogenization heat preservation treatment, the aluminum-scandium master alloy exhibits severe segregation.

[0083] Comparative Example 3: Preparation Method of an Aluminum-Schanddium Master Alloy

[0084] A method for preparing an aluminum-scandium master alloy, specifically comprising:

[0085] (1) Melting: Scandium oxide, molten salt and aluminum ingot are added to a non-vacuum medium frequency furnace, and the temperature is uniformly increased to 1050°C at a rate of 15 kW / h, and then kept stirred at 950°C for 30 minutes. The molten salt is scandium fluoride, potassium chloride, sodium fluoride, sodium chloride and cryolite. The mass ratio of scandium oxide, scandium fluoride, potassium chloride, sodium fluoride, sodium chloride, cryolite and aluminum ingot is 4:2:9:5.5:10:30:100.

[0086] (2) Impurity removal: introduce argon gas with a purity greater than 99.99% and blow argon for 10 minutes.

[0087] (3) Insulation: Insulate at 920°C for 1 hour.

[0088] (4) Slag removal and casting: After the insulation is completed, slag removal and casting are carried out, and the casting temperature is 800℃.

[0089] (5) Cooling: Set the temperature of the water-cooled mold circulating water to 10°C in advance and the flow rate to 0.8m 3 / h, the aluminum-scandium alloy liquid can be solidified and taken out in the water-cooled mold in 5 to 8 seconds.

[0090] (6) Sampling, analysis and testing of aluminum-scandium intermediate alloy.

[0091] Comparative Example 3 differs from Example 1 in that, in step (3) of Example 1, the holding time is at 925°C and 825°C for 30 minutes, respectively, while in step (3) of Comparative Example 3, the holding time is at 920°C for 1 hour. The results of the aluminum-scandium master alloy prepared in Comparative Example 3 are shown in Table 2. As can be seen from Table 2, only one holding period is required for the aluminum-scandium master alloy solution, which has little effect on the homogenization of the alloy.

[0092] Table 1 Results of aluminum-scandium master alloys of Examples 1, 2, and 3

[0093]

[0094] Table 2 Results of different positions of aluminum-scandium master alloys in Example 1 (homogenized) and Comparative Example 2 (unhomogenized)

[0095]

[0096] It is easy for those skilled in the art to understand that, under the premise of no conflict, the above-mentioned advantageous methods can be freely combined and superimposed. The above is only a preferred embodiment of the present application and is not intended to limit the present application. Any modifications, equivalent replacements and improvements made within the spirit and principles of the present application should be included in the scope of protection of the present application. The above is only a preferred embodiment of the present application. It should be pointed out that for ordinary technicians in this technical field, several improvements and variations can be made without departing from the technical principles of the present application. These improvements and variations should also be regarded as the scope of protection of the present application.

Claims

1. A method for preparing a homogenized aluminum-scandium master alloy, characterized by: include: Smelting: heating scandium oxide, molten salt and aluminum ingot to 1000-1200°C, then keeping and stirring at 900-1000°C for 30-60 minutes, wherein the mass ratio of scandium oxide, molten salt and aluminum ingot is 3.5-4.5:50-65:100; An aluminum-scandium master alloy liquid is obtained by removing impurities and performing two-step heat preservation, wherein the two heat preservation steps are respectively at 900-950° C. and 800-850° C. for 0.5-1 hour; The aluminum-scandium master alloy is obtained through slagging, casting and cooling, wherein the casting temperature is 750-800°C.

2. The method for preparing a homogenized aluminum-scandium master alloy according to claim 1, wherein: The smelting is carried out in a non-vacuum medium frequency furnace.

3. The method for preparing a homogenized aluminum-scandium master alloy according to claim 1, wherein: The temperature is raised at a constant speed of 10 to 20 kW / h.

4. The method for preparing a homogenized aluminum-scandium master alloy according to claim 1, wherein: The molten salt is scandium fluoride, potassium chloride, sodium fluoride, sodium chloride and cryolite, and the mass ratio is 1.5-2.5:8-10:5-6:9-11:30-32.

5. The method for preparing a homogenized aluminum-scandium master alloy according to claim 4, wherein: The mass ratio of scandium oxide, scandium fluoride, potassium chloride, sodium fluoride, sodium chloride, cryolite and aluminum ingot is 4:2:9:5.5:10:30:

100.

6. The method for preparing a homogenized aluminum-scandium master alloy according to claim 1, wherein: The impurity removal is as follows: introducing argon gas with a purity greater than 99.99% and blowing argon for 10 to 20 minutes.

7. The method for preparing a homogenized aluminum-scandium master alloy according to claim 1, wherein: The cooling is as follows: the water-cooled mold circulating water temperature is 5-15°C, and the flow rate is set to 0.5-1.5m 3 / h, cooling for 5 to 8 seconds.

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