High-strength and high-toughness aluminum alloy and preparation method thereof

Abstract

The invention relates to the technical field of aluminum alloys, in particular to a high-strength and high-toughness aluminum alloy and a preparation method thereof.The aluminum alloy comprises an aluminum alloy matrix, a reinforcing agent and an accelerant, the adding amount of the reinforcing agent is 0.3%-0.7% of the weight of the aluminum alloy matrix, the reinforcing agent is a mixture of nano titanium carbide, nano vanadium carbide and nano niobium carbide, and the accelerant is a mixture of nano titanium carbide, nano vanadium carbide and nano niobium carbide. The weight part ratio of the nano titanium carbide to the nano vanadium carbide to the nano niobium carbide is (4-6): (1-3): 1; the adding amount of the accelerant is 2.5-4.5% of the weight of the aluminum alloy matrix, and the accelerant comprises carbonyl nickel powder; the method has the advantage of simultaneously improving the strength and toughness of the aluminum alloy.

Description

Technical Field

[0001] The present application relates to the technical field of aluminum alloys, and in particular to a high-strength and high-toughness aluminum alloy and a preparation method thereof. Background Art

[0002] Aluminum alloy is the most widely used type of nonferrous metal structural material in industry. It has been widely used in aviation, aerospace, automobile, machinery manufacturing, shipbuilding and chemical industries. The rapid development of industrial economy has also put forward higher requirements on the performance of aluminum alloy. However, the α-Al and eutectic phase grains in conventional cast aluminum alloys are coarse, and the strength and toughness of the alloy cannot meet the requirements of bearing high loads. However, when using high-performance deformed alloys, the deformed alloys are prone to hot cracking when produced using die casting and liquid die forging processes.

[0003] In the related technology, nano-titanium carbide is added to refine the alloy matrix to improve the strength and toughness of the aluminum alloy. However, due to the poor wettability of the aluminum alloy matrix to titanium carbide, the prepared aluminum alloy has defects such as many microscopic pores and low strength. However, reducing the fineness of titanium carbide will increase its agglomeration in the matrix, resulting in the effect not being able to achieve the expected effect. Summary of the invention

[0004] In order to improve the strength and toughness of aluminum alloys at the same time, the present application provides a high-strength and high-toughness aluminum alloy and a preparation method thereof.

[0005] In a first aspect, the present application provides a high-strength and high-toughness aluminum alloy, using the following technical solution: A high-strength and high-toughness aluminum alloy, comprising an aluminum alloy matrix, a reinforcing agent and an accelerator, wherein the reinforcing agent is added in an amount of 0.3-0.7% of the weight of the aluminum alloy matrix, and is a mixture of nano-titanium carbide, nano-vanadium carbide and nano-niobium carbide, wherein the weight ratio of nano-titanium carbide, nano-vanadium carbide and nano-niobium carbide is (4-6): (1-3): 1; The added amount of the accelerator is 2.5-4.5% of the weight of the aluminum alloy matrix, and the accelerator includes carbonyl nickel powder.

[0006] By adopting the above technical scheme, nano titanium carbide, nano vanadium carbide and nano niobium carbide are added simultaneously, which has the best grain refining effect on the aluminum alloy. By refining the aluminum alloy grains, the mechanical strength of the aluminum alloy can be improved. On this basis, carbonyl nickel powder is added as a promoter. The carbonyl nickel powder can greatly improve the wetting effect of the aluminum alloy matrix on the reinforcing agent, thereby improving the dispersion of the nano-level reinforcing agent in the aluminum alloy matrix, and reducing the microscopic pores inside the aluminum alloy, so that the mechanical strength and toughness of the aluminum alloy are improved.

[0007] Preferably, the accelerator is a mixture of carbonyl nickel powder and molybdenum carbide powder.

[0008] By adopting the above technical solution, although molybdenum carbide can enhance the wetting effect of the aluminum alloy matrix on the reinforcing agent, the melting point of molybdenum carbide powder is relatively high, and it will not melt during the preparation process of the aluminum alloy, so that the improvement of its wetting effect on the aluminum alloy is small, resulting in a small improvement in the overall performance of the aluminum alloy; when carbonyl nickel powder and molybdenum carbide are added at the same time, it is found that the two have a synergistic effect. It is considered that the promoter achieves an unexpected improvement effect on the wetting effect of the aluminum alloy matrix, and the molybdenum carbide plays a wetting effect without melting, and can more easily enter between the agglomerated nano-scale reinforcing agent particles. The interface energy between the molybdenum carbide and the aluminum alloy matrix modified by the carbonyl nickel powder is relatively low, so that the aluminum alloy matrix can quickly wet and disperse the reinforcing agent, so that the mechanical properties of the aluminum alloy are greatly improved, and its elongation after fracture is also greatly improved.

[0009] Preferably, the weight ratio of the carbonyl nickel powder to the molybdenum carbide powder is 5:3.

[0010] By adopting the above technical solution, when the weight ratio of carbonyl nickel powder to molybdenum carbide powder is 5:3, the synergistic effect is the strongest.

[0011] Preferably, the amount of the accelerator added is 3.5% of the weight of the aluminum alloy matrix.

[0012] Preferably, the average particle size of the nano-titanium carbide is 30-40 nm, and the average particle size of the nano-vanadium carbide and the nano-niobium carbide is 500 nm.

[0013] By adopting the above technical solution, when the particle size of nano titanium carbide changes from 50nm to 30nm, the comprehensive performance of aluminum alloy is gradually improved; but when it is further refined to 20nm, its yield strength, tensile strength and elongation after fracture are reduced. It is speculated that when its particle size is 20nm, its particle size is too fine and it will inevitably agglomerate inside the aluminum alloy matrix. Therefore, the particle size of the reinforcing agent should not be less than 20nm. Considering the performance of aluminum alloy, the particle size of nano titanium carbide is 30-40nm, which is a better choice.

[0014] Preferably, the amount of the reinforcing agent added is 0.5% of the weight of the aluminum alloy matrix.

[0015] Preferably, the weight percentages of the chemical components of the aluminum alloy matrix are as follows: Si 1.2-1.7%, Mn 0.03-0.07%, Mg 0.08-0.12%, Ti 0.01-0.04%, Fe 0.1-0.2%, Cr 0.01-0.13%, Cu 0.6-0.9%, Zn 0.01-0.03%, the total amount of other impurity elements ≤0.15, and the balance is Al.

[0016] By adopting the above technical solution, the reinforcing agent and accelerator of the present application are suitable for this aluminum alloy matrix. The numerical values ​​within the range are not listed one by one in the embodiments, but in theory, the technical effects of the present application can be obtained.

[0017] Preferably, the weight percentage of Si is 1.5%.

[0018] By adopting the above technical solution, the addition amount of silicon powder is also a key factor affecting the mechanical properties of aluminum alloy. Silicon can play a role in solid solution strengthening of carbonyl nickel powder. Through the discussion of the addition amount of silicon powder, the weight percentage of silicon component is 1.5% which is the best.

[0019] In a second aspect, the present application provides a method for preparing a high-strength and high-toughness aluminum alloy, using the following technical solution: A method for preparing a high-strength and high-toughness aluminum alloy comprises the following steps: S1, preparing an aluminum alloy matrix melt; S2. Adding a promoter to the aluminum alloy matrix melt, stirring for 10-30 minutes, adding a reinforcing agent, stirring for 10-30 minutes, and adding a refining agent for refining, wherein the amount of the refining agent added is 0.15-0.35% by weight of the aluminum alloy matrix melt; S3. The temperature is controlled at 700-740°C, and nitrogen is introduced as a protective gas for degassing. The nitrogen pressure is 0.2-0.4MPa, the flow rate is 20-30L / min, the degassing speed is 500-700r / min, and the degassing time is 10-30min. After slag removal and degassing, let it stand, scrape off the slag on the surface of the melt, and die-cast to obtain aluminum alloy.

[0020] By adopting the above technical scheme, the reinforcing agent and the accelerator are added to the aluminum alloy matrix melt in sequence. The preparation method is relatively simple and suitable for mass production in factories. The texture of the obtained aluminum alloy is uniform and the qualified rate is high. In addition, the preparation method of the present application has good tolerance to process parameters.

[0021] In summary, the present application includes at least one of the following beneficial technical effects: 1. The simultaneous addition of nano-titanium carbide, nano-vanadium carbide and nano-niobium carbide has the best grain refining effect on aluminum alloys. By refining the grains of aluminum alloys, the mechanical strength of aluminum alloys can be improved. On this basis, carbonyl nickel powder is added as a promoter. Carbonyl nickel powder can greatly improve the wetting effect of the aluminum alloy matrix on the reinforcing agent, thereby improving the dispersion of nano-level reinforcing agents in the aluminum alloy matrix, and reducing the microscopic pores inside the aluminum alloy, thereby improving the mechanical strength and toughness of the aluminum alloy.

[0022] 2. The yield strength of the aluminum alloy prepared in this application is between 383-430MPa, and the tensile strength is between 420-450MPa. At the same time, its elongation after fracture can reach 14.1% or above, and can reach up to 18.4% at the highest; this shows that this application can simultaneously improve the mechanical strength and toughness of the aluminum alloy, giving the aluminum alloy greater application potential. DETAILED DESCRIPTION

[0023] The present application is further described in detail below in conjunction with the specific contents.

[0024] raw material The raw materials used in the examples of the present application are all purchased from the market, wherein the silicon powder is industrial silicon powder; the model of the refining agent is HJ-Q10; the average particle size of the carbonyl nickel powder is 2.9-3.6 μm; and the average particle size of the molybdenum carbide powder is 2.6-3.5 μm.

[0025] Example 1 A high-strength and high-toughness aluminum alloy comprises an aluminum alloy matrix, a reinforcing agent and an accelerator, wherein the percentages of the chemical components added to the aluminum alloy matrix are shown in Table 1, and the preparation method of the aluminum alloy is as follows: S1. Prepare pure aluminum ingot, silicon powder, metal magnesium, metal copper, metal zinc, Al-Mn master alloy, Al-Ti master alloy, Al-Fe master alloy and Al-Cr master alloy, heat each raw material to 140° C. for drying, and then mix the raw materials according to the chemical composition ratio in Table 1; the amount of reinforcing agent added is 0.5% by weight of the aluminum alloy matrix, and the amount of accelerator added is 3.5wt% by weight of the aluminum alloy matrix; In addition, the reinforcing agent is nano titanium carbide, nano vanadium carbide and nano niobium carbide, and the weight ratio of nano titanium carbide, nano vanadium carbide and nano niobium carbide is 5:2:1; the accelerator is carbonyl nickel powder; wherein the average particle size of nano vanadium carbide and nano niobium carbide is 500nm; the average particle size of nano titanium carbide is 30nm; S2, setting the melting temperature to 800°C, putting the pure aluminum ingot into the melting furnace, and after the pure aluminum ingot is completely melted, adding silicon, Al-Mn master alloy, Al-Fe master alloy, stirring until melted, adding Al-Ti master alloy and Al-Cr master alloy, stirring until completely melted, and continuing to add metal magnesium, metal copper and metal zinc for melting to obtain an aluminum alloy matrix melt; S3. After the aluminum alloy matrix melt is completely melted, stir for 15 minutes, perform melt composition analysis before the furnace, add or dilute the alloy according to the measured value, and adjust the melt composition; S4. Add a promoter to the aluminum alloy matrix melt, stir for 20 minutes, then add a reinforcing agent, stir for 15 minutes, then add a refining agent for refining, the amount of refining agent added accounts for 0.2wt% of the melt mass, and then introduce high-purity nitrogen as a protective gas for degassing. The pressure of high-purity nitrogen is 0.3MPa, the flow rate is 25L / min, the degassing speed is 600r / min, the degassing time is 15min, and the temperature is controlled at 840℃; after slag removal and degassing, let it stand for 20min, scrape off the scum on the surface of the melt and let it stand for 15min, and die-cast to obtain aluminum alloy.

[0026] Table 1 Weight percentage of chemical components of the aluminum alloy matrix of Example 1 (%)

[0027] Example 2 A high-strength and high-toughness aluminum alloy, which is different from Example 1 in that its promoter is a mixture of carbonyl nickel powder and molybdenum carbide powder, the weight ratio of carbonyl nickel powder to molybdenum carbide powder is 5:3, and the remaining steps are the same as Example 1.

[0028] Example 3 A high-strength and high-toughness aluminum alloy, which is different from Example 1 in that its promoter is a mixture of carbonyl nickel powder and molybdenum carbide powder, the weight ratio of carbonyl nickel powder to molybdenum carbide powder is 5:1, and the remaining steps are the same as Example 1.

[0029] Example 4 A high-strength and high-toughness aluminum alloy, which is different from Example 1 in that its promoter is a mixture of carbonyl nickel powder and molybdenum carbide powder, the weight ratio of carbonyl nickel powder to molybdenum carbide powder is 5:5, and the remaining steps are the same as Example 1.

[0030] Example 5 A high-strength and high-toughness aluminum alloy, which is different from Example 2 in that the average particle size of the nano-titanium carbide in its reinforcing agent is 20nm, and the remaining steps are the same as Example 2.

[0031] Example 6 A high-strength and high-toughness aluminum alloy, which is different from Example 2 in that the average particle size of the nano-titanium carbide in its reinforcing agent is 40nm, and the remaining steps are the same as Example 2.

[0032] Example 7 A high-strength and high-toughness aluminum alloy, which is different from Example 2 in that the average particle size of the nano-titanium carbide in its reinforcing agent is 50nm, and the remaining steps are the same as Example 2.

[0033] Example 8 A high-strength and high-toughness aluminum alloy, which is different from Example 2 in that the weight percentage of the silicon component in its aluminum alloy matrix is ​​1.2%, and the remaining steps are the same as Example 2.

[0034] Example 9 A high-strength and high-toughness aluminum alloy, which is different from Example 2 in that the weight percentage of the silicon component in its aluminum alloy matrix is ​​1.7%, and the remaining steps are the same as Example 2.

[0035] Example 10 A high-strength and high-toughness aluminum alloy, which is different from Example 2 in that the amount of reinforcing agent added is 0.3% of the weight of the aluminum alloy matrix, and the remaining steps are the same as Example 2.

[0036] Embodiment 11 A high-strength and high-toughness aluminum alloy, which is different from Example 2 in that the amount of reinforcing agent added is 0.7% of the weight of the aluminum alloy matrix, and the remaining steps are the same as Example 2.

[0037] Example 12 A high-strength and high-toughness aluminum alloy, which is different from Example 2 in that the amount of the accelerator added is 2.5% of the weight of the aluminum alloy matrix, and the remaining steps are the same as Example 2.

[0038] Example 13 A high-strength and high-toughness aluminum alloy, which is different from Example 2 in that the amount of the accelerator added is 4.5% of the weight of the aluminum alloy matrix, and the remaining steps are the same as Example 2.

[0039] Comparative Example 1 A high-strength and high-toughness aluminum alloy, which is different from Example 1 in that no accelerant is added, and the remaining steps are the same as Example 1.

[0040] Comparative Example 2 A high-strength and high-toughness aluminum alloy, which is different from Example 1 in that its promoter is molybdenum carbide powder, and the remaining steps are the same as Example 1.

[0041] Comparative Example 3 A high-strength and high-toughness aluminum alloy, which is different from Example 1 in that its reinforcing agent is nano-titanium carbide with an average particle size of 30 nm, and the remaining steps are the same as those of Example 1.

[0042] Comparative Example 4 A high-strength and high-toughness aluminum alloy, which is different from Example 1 in that its reinforcing agent is nano-vanadium carbide with an average particle size of 500nm, and the remaining steps are the same as those of Example 1.

[0043] Comparative Example 5 A high-strength and high-toughness aluminum alloy, which is different from Example 1 in that its reinforcing agent is nano-niobium carbide with an average particle size of 500nm, and the remaining steps are the same as those of Example 1.

[0044] Comparative Example 6 A high-strength and high-toughness aluminum alloy, which is different from Example 1 in that no reinforcing agent and accelerator are added to its raw materials, and the remaining steps are the same as Example 1.

[0045] Performance testing Detection method / test method Aluminum alloys were prepared according to the preparation methods of Examples 1-13 and Comparative Examples 1-6, respectively, and then tested according to the following testing methods. The test results are shown in Table 2.

[0046] Yield strength, tensile strength and elongation after fracture: test according to the test method in ASTM-B557.

[0047] Table 2 Test results of Examples 1-13 and Comparative Examples 1-6

[0048] It can be seen from the test data of Examples 1-13 and Comparative Examples 1-6 that the yield strength of the aluminum alloys prepared in the present application is between 383-430 MPa, and the tensile strength is between 420-450 MPa. At the same time, the elongation after fracture can reach 14.1% or above, and can reach up to 18.4% at the highest; this indicates that the present application can simultaneously improve the mechanical strength and elongation at fracture of the aluminum alloy, so that the aluminum alloy has greater application potential.

[0049] Since substances such as titanium carbide have the function of refining aluminum alloy grains and improving the alloy microstructure, thereby improving the mechanical properties of aluminum alloy. However, when the amount added is too large, due to the poor wettability of the aluminum alloy matrix to titanium carbide, the aluminum alloy has many microscopic pores, and the strength is relatively high but the amplitude is relatively low. Based on this, the use of nanomaterials will cause them to agglomerate inside the aluminum alloy matrix, and the expected effect cannot be achieved. For this reason, the inventors of the present application added carbonyl nickel powder as a promoter. It can be seen from the test data of Example 1 and Comparative Example 1 that carbonyl nickel powder can greatly improve the wetting effect of the aluminum alloy matrix on the reinforcing agent, thereby improving the dispersion of the nano-level reinforcing agent inside the aluminum alloy matrix, and reducing the microscopic pores inside the aluminum alloy, greatly improving the strength.

[0050] Combined with Comparative Example 2, when molybdenum carbide powder is used as a promoter, although molybdenum carbide can enhance the wetting effect of the aluminum alloy matrix on the reinforcing agent, the melting point of molybdenum carbide powder is relatively high, and it will not melt during the preparation process of the aluminum alloy, so the improvement of its wetting effect on the aluminum alloy is small, resulting in a small improvement in the overall performance of the aluminum alloy.

[0051] When carbonyl nickel powder and molybdenum carbide are added at the same time, it is found that the two have a synergistic effect, and when the weight ratio of carbonyl nickel powder to molybdenum carbide powder is 5:3, the synergistic effect is the strongest. It is considered that the wetting effect of the promoter on the aluminum alloy matrix is ​​improved, and the wetting effect of molybdenum carbide, which does not melt, can more easily enter between the agglomerated nano-scale reinforcement particles, and its interface energy with the aluminum alloy matrix modified by carbonyl nickel powder is low, so that the aluminum alloy matrix can quickly wet and disperse the reinforcement, greatly improve the mechanical properties of the aluminum alloy, and its elongation after fracture is also greatly improved. This can be verified by the test data of Examples 2-4. Combined with Examples 12-13, it is a better choice when the amount of promoter added is 3.5% of the weight of the aluminum alloy matrix.

[0052] It can be seen from the test data of Example 1 and Comparative Examples 3-5 that the simultaneous addition of nano-titanium carbide, nano-vanadium carbide and nano-niobium carbide has the best grain refinement effect on aluminum alloy. On this basis, in combination with Examples 5-7, by exploring the particle size of nano-titanium carbide, when its particle size changes from 50nm to 30nm, the comprehensive performance of the aluminum alloy is gradually improved; but when it is further refined to 20nm, its yield strength, tensile strength and elongation after fracture are all reduced. It is speculated that when its particle size is 20nm, its particle size is too fine and it will still inevitably agglomerate inside the aluminum alloy matrix. Therefore, the particle size of the reinforcing agent should not be less than 20nm; and according to the test data of Table 2, its particle size of 30-40nm is a better choice. And in combination with Examples 10-11, the addition amount of the reinforcing agent is 0.5% of the weight of the aluminum alloy matrix, which is optimal.

[0053] It can be seen from the test data of Example 2 and Examples 8-9 that the amount of silicon powder added is also a key factor affecting the mechanical properties of aluminum alloys. Silicon can play a role in solid solution strengthening of carbonyl nickel powder. Through the discussion of the amount of silicon powder added, the weight percentage of silicon component is 1.5% which is the best.

[0054] This specific embodiment is merely an explanation of the present invention and is not a limitation of the present invention. After reading this specification, those skilled in the art may make non-creative modifications to the present embodiment as needed. However, as long as they are within the scope of the claims of the present invention, they are protected by the patent law.

Claims

1. A high-strength and high-toughness aluminum alloy, characterized in that: The invention comprises an aluminum alloy matrix, a reinforcing agent and an accelerator, wherein the reinforcing agent is added in an amount of 0.3-0.7% of the weight of the aluminum alloy matrix, and is a mixture of nano-titanium carbide, nano-vanadium carbide and nano-niobium carbide, wherein the weight ratio of nano-titanium carbide, nano-vanadium carbide and nano-niobium carbide is (4-6): (1-3): 1; The added amount of the accelerator is 2.5-4.5% of the weight of the aluminum alloy matrix, and the accelerator includes carbonyl nickel powder.

2. The high-strength and high-toughness aluminum alloy according to claim 1, characterized in that: The accelerator is a mixture of carbonyl nickel powder and molybdenum carbide powder.

3. A high-strength and high-toughness aluminum alloy according to claim 2, characterized in that: The weight ratio of the carbonyl nickel powder to the molybdenum carbide powder is 5:

3.

4. The high-strength and high-toughness aluminum alloy according to claim 3, characterized in that: The added amount of the accelerator is 3.5% of the weight of the aluminum alloy matrix.

5. The high-strength and high-toughness aluminum alloy according to claim 1, characterized in that: The average particle size of the nano titanium carbide is 30-40 nm, and the average particle size of the nano vanadium carbide and the nano niobium carbide is 500 nm.

6. The high-strength and high-toughness aluminum alloy according to claim 5, characterized in that: The added amount of the reinforcing agent is 0.5% of the weight of the aluminum alloy matrix.

7. The high-strength and high-toughness aluminum alloy according to claim 1, characterized in that: The weight percentages of the chemical components of the aluminum alloy matrix are as follows: Si 1.2-1.7%, Mn 0.03-0.07%, Mg 0.08-0.12%, Ti 0.01-0.04%, Fe 0.1-0.2%, Cr 0.01-0.13%, Cu 0.6-0.9%, Zn 0.01-0.03%, the total amount of other impurity elements is ≤0.15, and the balance is Al.

8. The high-strength and high-toughness aluminum alloy according to claim 7, characterized in that: The weight percentage of Si is 1.5%.

9. A method for preparing the high-strength and high-toughness aluminum alloy according to any one of claims 1 to 8, characterized in that: It includes the following steps: S1, preparing an aluminum alloy matrix melt; S2. Adding a promoter to the aluminum alloy matrix melt, stirring for 10-30 minutes, adding a reinforcing agent, stirring for 10-30 minutes, and adding a refining agent for refining, wherein the amount of the refining agent added is 0.15-0.35% by weight of the aluminum alloy matrix melt; S3. The temperature is controlled at 820-850°C, and nitrogen is introduced as a protective gas for degassing. The nitrogen pressure is 0.2-0.4MPa, the flow rate is 20-30L / min, the degassing speed is 500-700r / min, and the degassing time is 10-30min. After slag removal and degassing, let it stand, scrape off the slag on the surface of the melt, and die-cast to obtain aluminum alloy.

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