High-strength rare earth aluminum alloy material and preparation method thereof

Abstract

The invention relates to a high-strength rare earth aluminum alloy material and a preparation method thereof.The preparation method comprises the following steps that 1, raw materials are weighed, mixed and put into a smelting furnace, the temperature is increased to be molten, full and uniform stirring is conducted, and first molten liquid is obtained; 2, inert gas is continuously blown into the first molten liquid from the bottom of the first molten liquid, slagging-off treatment is conducted, and second molten liquid is obtained; step 3, adding nanoscale praseodymium yttrium silicide into the second molten liquid, and continuing to fully stir to obtain third molten liquid; 4, the third molten liquid is subjected to heat preservation and standing treatment, casting molding is conducted, and an aluminum alloy coarse material is obtained; and 5, the aluminum alloy coarse material is subjected to annealing treatment, and after cooling, the high-strength rare earth aluminum alloy material is obtained. The rare earth elements praseodymium and yttrium are added in addition to conventional iron, copper, manganese and other elements, and the prepared aluminum alloy material has the advantages of being high in strength and toughness, also has excellent corrosion resistance and is very suitable for being used in coastal areas and heavy industrial areas.

Description

Technical Field

[0001] The present invention relates to the field of aluminum alloys, and in particular to a high-strength rare earth aluminum alloy material and a preparation method thereof. Background Art

[0002] Large aluminum profiles are widely used in aerospace and ground transportation carriage manufacturing. High-speed train carriages produced in various countries around the world have used a large number of aluminum alloy profiles. The market demand for high-performance aluminum alloy welding wires used with large aluminum profiles has surged, and is basically dependent on imports. The composition and ratio of welding wires are directly related to the performance of welding wires. Adding rare earth elements to aluminum alloys has a positive effect on improving the structure and properties of the alloys, but improper addition of rare earth elements will also form coarse intermetallic compounds, significantly reduce the mechanical properties, and cause huge waste of resources.

[0003] Generally, the addition of rare earth elements to aluminum alloy welding wire results in either limited improvement in welding wire performance and uneven improvement in performance indicators, with tensile strength improved but material plasticity and corrosion resistance not improved, which restricts the integrated performance of welding wire; or there is a large gap in corrosion resistance compared with ordinary aluminum alloys and stainless steel, which restricts the application of aluminum alloys and becomes a disadvantage of aluminum alloys. In practical applications, water, salt, sulfur dioxide, etc. in the environment cannot be avoided, especially in coastal areas and some heavy industrial areas. Due to high humidity, high salt content, and heavy pollution, the corrosion resistance of the material plays an important role in the service life of the product. How to improve the corrosion resistance of aluminum alloys is particularly important. Summary of the invention

[0004] In view of the problems existing in the prior art, the purpose of the present invention is to provide a high-strength rare earth aluminum alloy material and a preparation method thereof.

[0005] The purpose of the present invention is achieved by the following technical solutions:

[0006] In a first aspect, the present invention provides a method for preparing a high-strength rare earth aluminum alloy material, comprising the following steps:

[0007] Step 1, weighing aluminum powder, iron powder, copper powder, silicon powder, magnesium powder, manganese powder and titanium powder, mixing them into a furnace, heating them until they are melted, and stirring them evenly to obtain a first molten liquid;

[0008] Step 2, continuously blowing inert gas from the bottom of the first molten liquid, performing slag removal in the process, and obtaining a second molten liquid;

[0009] Step 3, adding nano-sized praseodymium yttrium silicide to the second molten liquid, and continuing to stir fully to obtain a third molten liquid;

[0010] Step 4, keeping the third molten liquid warm and allowing it to stand for a static treatment, and then placing it in a mold for casting to obtain a raw aluminum alloy material;

[0011] Step 5, annealing the aluminum alloy raw material, and obtaining a high-strength rare earth aluminum alloy material after cooling.

[0012] Preferably, in step 1, the purity of the aluminum powder, iron powder, copper powder, silicon powder, magnesium powder, manganese powder and titanium powder is ≥99.99%.

[0013] Preferably, in step 1, the temperature for heating and melting is 735-815°C.

[0014] Preferably, in step 2, the inert gas is at least one of helium, neon, argon and xenon.

[0015] Preferably, in step 3, the particle size of the nano-scale praseodymium yttrium silicide is 20-30 nm.

[0016] Preferably, in step 4, the standing treatment time is 15-25 minutes.

[0017] Preferably, in step 5, the annealing temperature is 380-450° C., and the annealing time is 1-2 h.

[0018] Preferably, in step 5, the cooling method is a combination of furnace cooling and air cooling; furnace cooling is first performed at a cooling rate of 3-5°C / min, and then air cooling is performed after the temperature drops to 200°C, and air cooling is performed naturally to room temperature.

[0019] Preferably, in step 3, the preparation process of nano-scale praseodymium yttrium silicide comprises:

[0020] S1. Weigh yttrium oxide (Y2O3) and praseodymium oxide (Pr6O 11 ) and silicon powder are mixed in a grinder, and after sufficient grinding, a grinding mixture is obtained;

[0021] S2, placing the ground mixture in a crucible, then placing the crucible in a graphite furnace, introducing an inert gas as a protective gas, heating to 1520-1660° C., keeping the temperature for 2-4 hours, then cooling to 1250-1300° C. for the first time, keeping the temperature for 2-4 hours again, and finally cooling to room temperature for the second time, so as to obtain large praseodymium yttrium silicide particles;

[0022] S3. The large praseodymium yttrium silicide particles are placed in a nano-scale pulverizer for pulverization, and after sieving, nano-scale praseodymium yttrium silicide is obtained.

[0023] Preferably, in S1, the particle size of yttrium oxide (Y2O3) is 1-2 μm, and the purity is ≥99.99%; the particle size of praseodymium oxide (Pr6O 11) has a particle size of 1-2 μm and a purity of ≥99.99%; the particle size of silicon powder has a particle size of 10-20 μm and a purity of ≥99.99%.

[0024] Preferably, in S1, the mass ratio of yttrium oxide, praseodymium oxide and silicon powder is 2.3-4.6:10.2-20.4:8.4-25.3.

[0025] More preferably, in S1, the mass ratio of yttrium oxide, praseodymium oxide and silicon powder is 3.2:16.3:16.8.

[0026] Preferably, in S1, the grinding time is 200-300 r / min, the grinding speed is 1-3 h, and the ball-to-material ratio is 2-3:1.

[0027] Preferably, in S2, the heating rate is 10-15°C / min, the first cooling rate is 5-10°C / min, and the second cooling rate is 10-20°C / min.

[0028] In a second aspect, the present invention provides a high-strength rare earth aluminum alloy material, wherein the rare earth aluminum alloy material comprises, calculated by mass ratio:

[0029] Mg: 1.64%-1.96%, Si: 0.52%-0.83%, Ti: 0.22%-0.38%, Cu: 0.14%-0.25%, Fe: 0.12%-0.30%, Mn: 0.03%-0.14%, Pr: 0.085%-0.168%, Y: 0.018%-0.036%; the balance is aluminum and other inevitable impurities.

[0030] The beneficial effects of the present invention are:

[0031] 1. The present invention prepares an aluminum alloy material. In addition to conventional elements such as iron, copper, and manganese, rare earth elements praseodymium and yttrium are added to the aluminum alloy material. The prepared aluminum alloy material not only has the advantages of high strength and high toughness, but also has excellent corrosion resistance, and is very suitable for use in coastal areas and heavy industrial areas.

[0032] 2. The rare earth elements praseodymium and yttrium added to the rare earth aluminum alloy material of the present invention are added in the form of nano-scale praseodymium yttrium silicide in the molten liquid. The nano-scale praseodymium yttrium silicide can form a coarse dispersed phase, thereby effectively inhibiting crystallization, preventing crack propagation, and improving the ductility and toughness of the aluminum alloy.

[0033] 3. The present invention uses two rare earth elements, praseodymium and yttrium, to form a composite rare earth silicide, and obtains a suitable ratio through experiments. Compared with single praseodymium silicide or yttrium silicide, it can have a better enhancement effect on the strength and toughness of aluminum alloy materials, especially in terms of corrosion resistance. DETAILED DESCRIPTION

[0034] The technical solution of the present invention is described below through specific examples. It should be understood that the one or more method steps mentioned in the present invention do not exclude the existence of other method steps before and after the combination step or the insertion of other method steps between these explicitly mentioned steps; it should also be understood that these embodiments are only used to illustrate the present invention and are not used to limit the scope of the present invention. Moreover, unless otherwise specified, the numbering of each method step is only a convenient tool for identifying each method step, and is not intended to limit the order of arrangement of each method step or to limit the scope of the present invention. The change or adjustment of the relative relationship thereof shall also be regarded as the scope of the present invention without substantially changing the technical content.

[0035] In order to better understand the above technical scheme, the exemplary embodiments of the present invention are described in more detail below. Although exemplary embodiments of the present invention are shown, it should be understood that the present invention can be implemented in various forms and should not be limited by the embodiments set forth herein. On the contrary, these embodiments are provided in order to enable a more thorough understanding of the present invention and to enable the scope of the present invention to be fully communicated to those skilled in the art.

[0036] The present invention will be further described below in conjunction with the following examples.

[0037] Example 1

[0038] A high-strength rare earth aluminum alloy material, calculated by mass ratio, comprising:

[0039] Mg: 1.72%, Si: 0.66%, Ti: 0.25%, Cu: 0.22%, Fe: 0.12%, Mn: 0.1%, Pr: 0.135%, Y: 0.025%; the balance is aluminum and other inevitable impurities.

[0040] The method for preparing the above-mentioned high-strength rare earth aluminum alloy material comprises the following steps:

[0041] Step 1, weighing aluminum powder, iron powder, copper powder, silicon powder, magnesium powder, manganese powder and titanium powder, all with a purity of ≥99.99%, mixing them into a melting furnace, heating them to 785° C., and stirring them evenly after melting to obtain a first molten liquid;

[0042] Step 2, continuously blowing argon gas from the bottom of the first molten liquid, performing slag removal in the process, to obtain a second molten liquid;

[0043] Step 3, adding nano-sized praseodymium yttrium silicide with a particle size of 20-30 nm into the second molten liquid, and continuing to stir fully to obtain a third molten liquid;

[0044] Step 4, keeping the third molten liquid at a temperature for 20 minutes, and then placing it in a mold for casting to obtain a raw aluminum alloy material;

[0045] Step 5, annealing the aluminum alloy raw material at 420°C for 1.5h, and then cooling it by combining furnace cooling and air cooling, that is, first cooling it with the furnace at a cooling rate of 4°C / min, cooling it to 200°C and then naturally cooling it to room temperature to obtain a high-strength rare earth aluminum alloy material.

[0046] In the above step 3, the preparation process of nano-scale praseodymium yttrium silicide includes:

[0047] S1. Weigh yttrium oxide (Y2O3) with a particle size of 1 μm and praseodymium oxide (Pr6O 11 ) and silicon powder with a particle size of 10 μm are mixed in a grinder, the mass ratio of yttrium oxide, praseodymium oxide and silicon powder is 3.2:16.3:16.8, and grinding is performed. The grinding time is 250 r / min, the grinding speed is 2 h, and the ball-to-material ratio is 2.5:1. After sufficient grinding, a grinding mixture is obtained;

[0048] S2, placing the ground mixture in a crucible, then placing the crucible in a graphite furnace, introducing an inert gas as a protective gas, heating to 1580°C, heating at a rate of 12°C / min, and heat preservation for 3 hours, then cooling to 1250°C for the first time, cooling at a rate of 8°C / min, heat preservation again for 3 hours, and finally cooling to room temperature for the second time, cooling at a rate of 15°C / min, to obtain large praseodymium yttrium silicide particles;

[0049] S3. The large praseodymium yttrium silicide particles are placed in a nano-scale pulverizer for pulverization, and after sieving, nano-scale praseodymium yttrium silicide is obtained.

[0050] Example 2

[0051] A high-strength rare earth aluminum alloy material, calculated by mass ratio, comprising:

[0052] Mg: 1.64%, Si: 0.52%, Ti: 0.38%, Cu: 0.14%, Fe: 0.30%, Mn: 0.03%, Pr: 0.085%, Y: 0.018%; the balance is aluminum and other inevitable impurities.

[0053] The method for preparing the above-mentioned high-strength rare earth aluminum alloy material comprises the following steps:

[0054] Step 1, weighing aluminum powder, iron powder, copper powder, silicon powder, magnesium powder, manganese powder and titanium powder, all with a purity of ≥99.99%, mixing them into a furnace, heating them to 735° C., and stirring them evenly after melting to obtain a first molten liquid;

[0055] Step 2, continuously blowing argon gas from the bottom of the first molten liquid, performing slag removal in the process, to obtain a second molten liquid;

[0056] Step 3, adding nano-sized praseodymium yttrium silicide with a particle size of 20-30 nm into the second molten liquid, and continuing to stir fully to obtain a third molten liquid;

[0057] Step 4, keeping the third molten liquid at a temperature for 15 minutes, and then placing it in a mold for casting to obtain a raw aluminum alloy material;

[0058] Step 5, annealing the aluminum alloy raw material at 380°C for 2h, and then cooling it by combining furnace cooling and air cooling, that is, first cooling it in the furnace at a cooling rate of 3°C / min, cooling it to 200°C and then naturally cooling it to room temperature to obtain a high-strength rare earth aluminum alloy material.

[0059] In step 3, the preparation process of nano-scale praseodymium yttrium silicide includes:

[0060] S1. Weigh yttrium oxide (Y2O3) with a particle size of 2 μm and praseodymium oxide (Pr6O 11 ) and silicon powder with a particle size of 20 μm are mixed in a grinder, the mass ratio of yttrium oxide, praseodymium oxide and silicon powder is 2.3:10.2:8.4, and grinding is performed. The grinding time is 200 r / min, the grinding speed is 1 h, and the ball-to-material ratio is 2:1. After sufficient grinding, a grinding mixture is obtained;

[0061] S2, placing the ground mixture in a crucible, then placing the crucible in a graphite furnace, introducing an inert gas as a protective gas, heating to 1520°C, heating at a rate of 10°C / min, and heat preservation for 4 hours, then cooling to 1250°C for the first time, cooling at a rate of 5°C / min, heat preservation again for 4 hours, and finally cooling to room temperature for the second time, cooling at a rate of 10°C / min, to obtain large praseodymium yttrium silicide particles;

[0062] S3. The large praseodymium yttrium silicide particles are placed in a nano-scale pulverizer for pulverization, and after sieving, nano-scale praseodymium yttrium silicide is obtained.

[0063] Example 3

[0064] A high-strength rare earth aluminum alloy material, calculated by mass ratio, comprising:

[0065] Mg: 1.96%, Si: 0.83%, Ti: 0.22%, Cu: 0.25%, Fe: 0.18%, Mn: 0.14%, Pr: 0.168%, Y: 0.036%; the balance is aluminum and other inevitable impurities.

[0066] The method for preparing the above-mentioned high-strength rare earth aluminum alloy material comprises the following steps:

[0067] Step 1, weighing aluminum powder, iron powder, copper powder, silicon powder, magnesium powder, manganese powder and titanium powder, all with a purity of ≥99.99%, mixing them into a melting furnace, heating them to 815° C., and stirring them evenly after melting to obtain a first molten liquid;

[0068] Step 2, continuously blowing argon gas from the bottom of the first molten liquid, performing slag removal in the process, to obtain a second molten liquid;

[0069] Step 3, adding nano-sized praseodymium yttrium silicide with a particle size of 20-30 nm into the second molten liquid, and continuing to stir fully to obtain a third molten liquid;

[0070] Step 4, keeping the third molten liquid at a temperature for 25 minutes, and then placing it in a mold for casting to obtain a raw aluminum alloy material;

[0071] Step 5, annealing the aluminum alloy raw material at 450°C for 1h, and then cooling it by combining furnace cooling and air cooling, that is, first cooling it in the furnace at a cooling rate of 5°C / min, cooling it to 200°C and then naturally cooling it to room temperature to obtain a high-strength rare earth aluminum alloy material.

[0072] In step 3, the preparation process of nano-scale praseodymium yttrium silicide includes:

[0073] S1. Weigh yttrium oxide (Y2O3) with a particle size of 1 μm and praseodymium oxide (Pr6O 11 ) and silicon powder with a particle size of 10 μm are mixed in a grinder, the mass ratio of yttrium oxide, praseodymium oxide and silicon powder is 4.6:20.4:25.3, and grinding is performed. The grinding time is 300 r / min, the grinding speed is 3 h, and the ball-to-material ratio is 3:1. After sufficient grinding, a grinding mixture is obtained;

[0074] S2, placing the ground mixture in a crucible, then placing the crucible in a graphite furnace, introducing an inert gas as a protective gas, heating to 1660°C, heating at a rate of 15°C / min, and heat preservation for 2 hours, then cooling to 1300°C for the first time, cooling at a rate of 10°C / min, heat preservation again for 2 hours, and finally cooling to room temperature for the second time, cooling at a rate of 20°C / min, to obtain large praseodymium yttrium silicide particles;

[0075] S3. The large praseodymium yttrium silicide particles are placed in a nano-scale pulverizer for pulverization, and after sieving, nano-scale praseodymium yttrium silicide is obtained.

[0076] Comparative Example 1

[0077] A rare earth aluminum alloy material, the preparation process of which is different from that of Example 1 in that in step 3, nano-scale praseodymium yttrium silicide is replaced with commercially available nano-scale praseodymium disilicide, and the rest of the process and addition amount are the same as those of Example 1.

[0078] Comparative Example 2

[0079] A rare earth aluminum alloy material, the preparation process of which is different from that of Example 1 in that in step 3, the nano-scale praseodymium yttrium silicide is replaced with commercially available nano-scale yttrium disilicide, and the rest of the process and addition amount are the same as those of Example 1.

[0080] Comparative Example 3

[0081] A rare earth aluminum alloy material, the preparation process of which is different from that of Example 1 in that in step 3, nanometer-scale praseodymium yttrium silicide is replaced by a commercially available mixture of nanometer-scale praseodymium disilicide and nanometer-scale yttrium disilicide, the mass ratio of praseodymium disilicide to yttrium disilicide is 3.2:16.3, and the remaining processes and addition amounts are the same as those of Example 1.

[0082] In order to more clearly illustrate the content of the present invention, the strength, toughness and corrosion resistance of the rare earth aluminum alloy materials prepared in Example 1 and Comparative Examples 1-3 were tested and compared.

[0083] Among them, the tensile strength, yield strength and elongation are tested with reference to the standard GB / T 228.1-2010; the elastic modulus is tested with reference to the standard GB / T 5166-2023; the impact energy resistance is tested with reference to the standard GB / T 229-2007; corrosion resistance includes intergranular corrosion (test reference GB / T 7998-2005), exfoliation corrosion (test reference GB / T 22639-2022) and stress corrosion index (stress corrosion index Issrt in 3.5% NaCl solution, test reference HB 7235-1995).

[0084] The results are shown in Table 1 below:

[0085] Table 1 Performance comparison of different rare earth aluminum alloy materials

[0086]

[0087] It can be seen from Table 1 that the rare earth aluminum alloy material prepared in Example 1 of the present invention not only has high strength and good toughness, but also has excellent corrosion resistance.

[0088] In the description of this specification, the description with reference to the terms "one embodiment", "some embodiments", "example", "specific example", or "some examples" etc. means that the specific features, structures, materials or characteristics described in conjunction with the embodiment or example are included in at least one embodiment or example of the present invention. In this specification, the schematic representation of the above terms should not be understood as necessarily being directed to the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described may be combined in any one or more embodiments or examples in a suitable manner. In addition, those skilled in the art may combine and combine different embodiments or examples described in this specification.

[0089] Although the embodiments of the present invention have been shown and described above, it is to be understood that the above embodiments are exemplary and are not to be construed as limitations of the present invention. A person skilled in the art may change, modify, replace and vary the above embodiments within the scope of the present invention.

Claims

1. A method for preparing a high-strength rare earth aluminum alloy material, characterized in that: The following steps are involved: Step 1, weighing aluminum powder, iron powder, copper powder, silicon powder, magnesium powder, manganese powder and titanium powder, mixing them into a furnace, heating them until they are melted, and stirring them evenly to obtain a first molten liquid; Step 2, continuously blowing inert gas from the bottom of the first molten liquid, performing slag removal in the process, and obtaining a second molten liquid; Step 3, adding nano-sized praseodymium yttrium silicide to the second molten liquid, and continuing to stir fully to obtain a third molten liquid; Step 4, keeping the third molten liquid warm and allowing it to stand for a static treatment, and then placing it in a mold for casting to obtain a raw aluminum alloy material; Step 5, annealing the aluminum alloy raw material, and obtaining a high-strength rare earth aluminum alloy material after cooling.

2. The method for preparing a high-strength rare earth aluminum alloy material according to claim 1, characterized in that: In the step 1, the temperature of heating and melting is 735-815°C.

3. The method for preparing a high-strength rare earth aluminum alloy material according to claim 1, characterized in that: In step 2, the inert gas is at least one of helium, neon, argon and xenon.

4. The method for preparing a high-strength rare earth aluminum alloy material according to claim 1, characterized in that: In step 3, the particle size of the nano-scale praseodymium yttrium silicide is 20-30 nm.

5. The method for preparing a high-strength rare earth aluminum alloy material according to claim 1, characterized in that: In the step 5, the annealing temperature is 380-450°C, and the annealing time is 1-2h; the cooling method is a combination of furnace cooling and air cooling; furnace cooling is first performed at a cooling rate of 3-5°C / min, and then air cooling is performed after the temperature drops to 200°C, and air cooling is performed naturally to room temperature.

6. The method for preparing a high-strength rare earth aluminum alloy material according to claim 1, characterized in that: In step 3, the preparation process of nano-scale praseodymium yttrium silicide includes: S1, weighing yttrium oxide, praseodymium oxide and silicon powder and mixing them in a grinder, and after sufficient grinding, obtaining a grinding mixture; S2, placing the ground mixture in a crucible, then placing the crucible in a graphite furnace, introducing an inert gas as a protective gas, heating to 1520-1660° C., keeping the temperature for 2-4 hours, then cooling to 1250-1300° C. for the first time, keeping the temperature for 2-4 hours again, and finally cooling to room temperature for the second time, so as to obtain large praseodymium yttrium silicide particles; S3. The large praseodymium yttrium silicide particles are placed in a nano-scale pulverizer for pulverization, and after sieving, nano-scale praseodymium yttrium silicide is obtained.

7. The method for preparing a high-strength rare earth aluminum alloy material according to claim 6, characterized in that: In the S1, the mass ratio of yttrium oxide, praseodymium oxide and silicon powder is 2.3-4.6:10.2-20.4:8.4-25.

3.

8. The method for preparing a high-strength rare earth aluminum alloy material according to claim 6, characterized in that: In S1, the grinding time is 200-300 r / min, the grinding speed is 1-3 h, and the ball-to-material ratio is 2-3:

1.

9. The method for preparing a high-strength rare earth aluminum alloy material according to claim 6, characterized in that: In S2, the heating rate is 10-15°C / min, the first cooling rate is 5-10°C / min, and the second cooling rate is 10-20°C / min.

10. A high-strength rare earth aluminum alloy material, characterized in that: The rare earth aluminum alloy material is prepared by the preparation method of claim 1, and the rare earth aluminum alloy material, calculated by mass ratio, includes: Mg: 1.64%-1.96%, Si: 0.52%-0.83%, Ti: 0.22%-0.38%, Cu: 0.14%-0.25%, Fe: 0.12%-0.30%, Mn: 0.03%-0.14%, Pr: 0.085%-0.168%, Y: 0.018%-0.036%; the balance is aluminum and other inevitable impurities.

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