Aluminum alloy for new energy vehicle asynchronous motor rotor and preparation method thereof

Abstract

The application discloses a new energy automobile asynchronous motor rotor aluminum alloy and a preparation method thereof, and comprises 0.2-0.7wt.% Fe, 1.5-2.5wt.% Ni, 0.05-0.15wt.% B, 0.005-0.1wt.% Cr, Mn+V+Ti≤0.02wt.% and the balance of Al and impurities, wherein the total content of the impurities is not more than 0.02%. The application does not need to add rare earth elements and has low Ni element content, simple process flow, low comprehensive production cost, simple alloy component design and excellent comprehensive performance. Through the matching of the alloy component design and the production process, the application solves the problems that the prior art cannot meet the comprehensive performance requirements of the high-speed motor rotor forming performance, mechanical performance and electric conductivity, and has the advantages of simple process flow and low production cost.

Description

Technical Field

[0001] This invention relates to the field of new energy and new materials technology, specifically to an aluminum alloy for the rotor of an asynchronous motor for new energy vehicles and its preparation method. Background Technology

[0002] The asynchronous motor used in new energy vehicles mainly consists of two basic parts: a stator and a rotor. The stator generates a magnetic field, while the rotor cuts the rotating magnetic field of the stator to generate induced electromotive force and current, forming electromagnetic torque that causes the motor to rotate. When current passes through the rotor, heat is generated due to resistance losses, reducing motor efficiency. Simultaneously, heat transfer to other components causes the motor temperature to rise. If the heat cannot be dissipated in time, stress will occur between the rotor components due to differences in their coefficients of thermal expansion. Therefore, to improve motor efficiency and achieve higher speeds, the rotor must have high electrical conductivity to reduce resistance losses (accounting for 20%-25% of the overall motor losses) and lower temperature rise; furthermore, the rotor must have higher strength to withstand the centrifugal force generated by high-speed rotation.

[0003] The shortcomings of existing technology:

[0004] Currently, the main approach is to refine the Fe phase and improve the alloy's strength by adding Ni / Zr composites and Er / La rare earth elements to Al-Ni-Fe alloys. Simultaneously, introducing a specific proportion of boron (B) purifies the melt and improves the alloy's conductivity. However, rare earth elements are expensive and require cryogenic frosting to prepare Al-Er-La nanocrystals for addition, resulting in a complex process and high production costs. Alternatively, another approach involves adding a certain amount of strengthening element Mg and rare earth element Ce to Al-Ni-Fe alloys to improve strength, while adding trace amounts of B to purify the melt and improve conductivity. This alloy requires 3.0–6.5 wt.% Ni and also needs additional Ce, leading to high overall costs and low material economics. Alternatively, the alloy composition may be overly complex. Summary of the Invention

[0005] The purpose of this invention is to provide an aluminum alloy for the rotor of an asynchronous motor for new energy vehicles and a method for preparing the same, so as to solve the problems mentioned in the background art.

[0006] To achieve the above objectives, the present invention provides the following technical solution: an aluminum alloy for the rotor of an asynchronous motor for new energy vehicles, comprising the following materials by mass percentage: 0.2-0.7 wt.% Fe, 1.5-2.5 wt.% Ni, 0.05-0.15 wt.% B, 0.005-0.1 wt.% Cr, Mn+V+Ti≤0.02 wt.%, with the balance being Al and impurities, and the total impurity content not exceeding 0.02%.

[0007] Preferably, the mass relationship between Ni and Fe is as follows:

[0008] 1.8≤Ni+Fe≤2.5;

[0009] The mass ratio of Ni to Fe is 5-10.

[0010] This invention also provides a method for preparing aluminum alloy for the rotor of an asynchronous motor in a new energy vehicle, the method specifically including the following steps:

[0011] S1. Clean the smelting furnace, add aluminum ingots and heat until melted, spray the surface of the melt with a first-level refining agent, stir evenly and let stand for 10-20 minutes, remove the slag and pour out the furnace wash material a.

[0012] S2. Add the Fe, Ni and Cr raw materials according to the alloy composition ratio into the melting furnace in sequence, heat and melt them, and stir evenly to obtain alloy melt b.

[0013] S3. Degas and perform secondary refining on alloy melt b. After degassing, let it stand for 20-30 minutes. After removing the slag, add the proportioned B element to obtain alloy melt c.

[0014] S4. Pour the alloy melt c into a metal mold and cast it to obtain an alloy ingot.

[0015] Preferably, in step S1, the primary refining agent is a mixture of KCl, KBF4, and B4C, and the ratio of the primary refining agent is (20%~30%) KCl + (40%~50%) KBF4 + (10%~20%) B4C, and the amount of primary refining agent added is 0.1~0.3% of the total mass of the alloy melt.

[0016] Preferably, in step S1, the total amount of trace elements Mn+V+Ti in the furnace feed a does not exceed 0.02%, and the total amount of impurities does not exceed 0.05 wt.%.

[0017] Preferably, in step S2, Fe, Ni, Cr elements are added simultaneously with Al, heated to above 780°C until completely melted, and then the temperature of the molten aluminum is adjusted to within the range of 720°C ± 5°C, stirred thoroughly, and then allowed to stand.

[0018] Preferably, in step S3, the degassing temperature is set to 720~730℃, the degassing medium is N2, and the secondary refining agent is a mixture of Na3AlF6, KCl, La2O3, and CeO2. The refining agent ratio is: (20%~30%) Na3AlF6 + (20%~30%) KCl + (10%~20%) La2O3 + (10%~20%) Ce2O3. The amount of secondary refining agent added is 0.2%~0.3% of the total melt mass. The degassing time is 15~30 min, and after degassing, the melt is allowed to stand for 20~30 min. During the standing process, the melt temperature is set to drop to 700℃-710℃. After slag removal, the proportioned B element is added, stirred for 2-3 min, and then cast, ensuring that the alloy melt density is ≥2.65 g / cm³. 3 .

[0019] Preferably, the casting temperature is in the range of 700±5℃ and the mold temperature is 150~200℃.

[0020] Preferably, after the alloy ingot undergoes a low-temperature short-time aging treatment at 250℃ for 1 hour, the tensile strength is ≥110MPa, the yield strength is ≥60MPa, the elongation is ≥20%, and the electrical conductivity is ≥33MS / m.

[0021] Preferably, the alloy ingot is suitable for die-casting production processes of high-strength, high-conductivity parts such as rotors for new energy vehicle motors.

[0022] Compared with the prior art, the beneficial effects of the present invention are:

[0023] This invention discloses an aluminum alloy for the rotor of an asynchronous motor for new energy vehicles and its preparation method. It does not require the addition of rare earth elements and has a low Ni content. The process is simple, the overall production cost is low, the alloy composition design is simple, and the overall performance is excellent. It aims to solve the problem that existing technologies cannot meet the comprehensive performance requirements of high-speed motor rotors in terms of forming performance, mechanical performance, and electrical conductivity by matching the alloy composition design and production process. At the same time, it has the advantages of simple process and low production cost.

[0024] In this invention, the primary refining agent mainly functions to remove residual impurities such as Mn, Ti, and V from the furnace charge. KCl primarily provides a chlorine source, combining with Mn in the melt to form MnCl2 chloride, which has a high vapor pressure within the aluminum melt temperature range (700-750℃) and readily volatilizes during stirring. KBF4 primarily provides a boron source, reacting with Ti and V to form high-density, high-melting-point borides, whose density is significantly higher than that of molten aluminum, facilitating rapid sedimentation and separation. The addition of B4C serves two purposes: firstly, it synergistically works with KBF4 to promote the combination of B with Ti and V; secondly, it reacts with residual Si in the melt to form SiC, reducing the impact of free Si on subsequent alloy smelting processes.

[0025] The addition of Fe in this invention is primarily to ensure smooth demolding during die casting and to improve the room temperature and high temperature yield strength of the material. However, increased Fe content can lead to the formation of coarse Fe-containing phases, affecting the alloy's elongation and electrical conductivity. Similarly, the addition of Ni can improve the alloy's room temperature and high temperature strength. Furthermore, the small solidification range and good fluidity of Al-Ni ensure the alloy's die casting performance. In addition, Ni addition helps improve the Fe phase morphology, transforming it from long needle-like structures to short rod-like structures, reducing the adverse effects of Fe on electrical conductivity. The addition of Cr not only refines the α-Al grain structure but also promotes the refinement of Al3Ni grains. However, excessive Cr content increases the supersaturation of the solid solution, reduces the compositional supercooling of the liquid phase at the solidification front of the melt, increases the crystallization range of the alloy melt, and leads to grain growth. Furthermore, Cr can also form Al with Fe. 13 The (Cr,Fe)2 phase increases the precipitation temperature of the Al-Fe phase, which is beneficial to improving the thermal stability of the alloy. However, the increased Cr content reduces the alloy's fluidity and affects its formability. The addition of boron (B) not only purifies the melt but also improves the alloy's mechanical properties and electrical conductivity. When the alloy already contains Cr, it readily combines with B to form borides, affecting the alloy's properties. Therefore, during the degassing process, the temperature of the melt is adjusted to 700-710℃, and 0.005-0.1wt% B is added. After slag removal, the properly proportioned B is added, stirred for 2-3 minutes, and then immediately cast. This process not only purifies the melt but also improves the alloy's mechanical properties and electrical conductivity without forming borides with Cr.

[0026] In this invention, the secondary refining agent primarily functions in conjunction with the degassing medium N2 to remove oxide inclusions, trace impurities, hydrogen, and other contaminants from the Al-Ni-Fe-Cr melt. Considering that 0.005-0.1 wt.% Cr has already been added to the melt, a boron-free refining agent was specifically designed to prevent it from reacting with boron (B) during prolonged high-temperature refining to form the CrB2 phase and negate the effects of Cr. Na3AlF6 serves two main purposes: firstly, its ionic state after melting provides a strong dissolving ability for alumina inclusions, significantly reducing alumina particle size and promoting flotation; secondly, its synergistic effect with N2 encapsulates hydrogen bubbles, accelerating their flotation; and thirdly, it reduces melt viscosity, improving fluidity and facilitating uniform diffusion of the refining agent and slag-aluminum separation. The addition of KCl serves two purposes: firstly, it provides a chlorine source, combining with Mn in the melt to form MnCl2 chloride, thus reducing the trace Mn content in the melt; secondly, it utilizes its synergistic effect with Na3AlF6 to lower the melting point, preventing the formation of high-melting-point cryolite residues in the melt, which could become crack initiations and affect the quality of subsequent alloying. The addition of La2O3 primarily utilizes its ease of forming LaV with V. 11 The addition of CeO2, a stable intermetallic compound, is mainly to utilize its reaction with Ti to form CeTiAl. 12 Intermetallic compounds, both with densities greater than 4.2 g / cm³. 3 It can be removed by sedimentation during the settling process. It should be noted that the combined addition of rare earth oxides and Na3AlF6 may lead to negative effects such as increased slag viscosity, aggravated sodium contamination, and rare earth failure. These risks need to be mitigated through formula optimization and process adjustment. Attached Figure Description

[0027] Figure 1 This is a metallographic photograph of the Al-Ni-Fe-Cr alloy of the present invention. Detailed Implementation

[0028] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0029] In the description of this invention, it should be understood that the terms "center," "longitudinal," "lateral," "length," "width," "thickness," "upper," "lower," "top," "bottom," "inner," "outer," "clockwise," and "counterclockwise," etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are only for the convenience of describing this invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on this invention.

[0030] In the description of this patent, it should be noted that, unless otherwise explicitly specified and limited, the terms "installation," "connection," and "setting" should be interpreted broadly. For example, they can refer to a fixed connection or setting, a detachable connection or setting, or an integrated connection or setting. Those skilled in the art can understand the specific meaning of the above terms in this patent according to the specific circumstances.

[0031] Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include one or more of that feature. In the description of this invention, "a number" means two or more, unless otherwise explicitly specified.

[0032] Example 1

[0033] Please see Figure 1 As shown, the present invention provides an aluminum alloy technical solution for the rotor of an asynchronous motor for new energy vehicles: the material comprises the following by mass percentage: 0.45wt.% Fe, 2wt.% Ni, 0.1wt.% B, 0.1wt.% Cr, Mn+V+Ti≤0.02wt.%, with the balance being Al and impurities, the total impurity content not exceeding 0.02%; the mass relationship between Ni and Fe is 1.8≤Ni+Fe≤2.5, and the mass ratio between Ni and Fe is 5-10.

[0034] This invention also provides a method for preparing aluminum alloy for the rotor of an asynchronous motor in a new energy vehicle, the method specifically including the following steps:

[0035] S1. Clean the smelting furnace thoroughly, add aluminum ingots and heat until melted. Spray the primary refining agent onto the surface of the melt, stir evenly, and let it stand for 10-20 minutes. After removing the slag, pour out the furnace wash charge a. The primary refining agent is a mixture of KCl, KBF4, and B4C. The ratio of the primary refining agent is: 25% KCl, 40% KBF4, and 10% B4C. The amount of primary refining agent added is 0.1-0.3% of the total mass of the alloy melt. The trace elements in furnace wash charge a are Mn: 0.004%, V: 0.008%, and Ti: 0.003%. The total amount of Mn+V+Ti elements is 0.015%, and the total amount of impurities does not exceed 0.05 wt.%. The composition of the melt after removing the slag is analyzed. The results show that the total amount of Mn+V+Ti elements reaches 0.036%.

[0036] S2. Add the Fe, Ni, and Cr raw materials according to the alloy composition ratio into the melting furnace in sequence, heat and melt them, and stir evenly to obtain alloy melt b. Add Fe, Ni, and Cr elements and Al at the same time, heat to above 780℃ until completely melted, then adjust the temperature of the aluminum liquid to within the range of 720℃±5℃, stir thoroughly and let stand.

[0037] S3. Degas and perform secondary refining on alloy melt b. After degassing, let it stand for 20-30 minutes. After removing the slag, add the pre-proportioned B element to obtain alloy melt c. Set the degassing temperature to 720-730℃, the degassing medium to N2, and the secondary refining agent to a mixture of Na3AlF6, KCl, La2O3, and CeO2. The refining agent ratio is: 20% Na3AlF6, 20% KCl, 10% La2O3, and 10% Ce2O3. The amount of secondary refining agent added is 0.2%-0.3% of the total melt mass. The degassing time is 15-30 minutes. After degassing, let it stand for 20-30 minutes. During the standing process, set the melt temperature to 700℃-710℃. After removing the slag, add the pre-proportioned B element, ensuring that the density of alloy melt c is ≥2.65 g / cm³. 3 The trace elements in melt c are Mn: 0.003%, V: 0.006%, and Ti: 0.002%, with a total Mn+V+Ti element content of 0.011%. The melt is stirred for 2-3 minutes and then immediately poured.

[0038] S4. The alloy melt c is poured into a metal mold and cast to form an alloy ingot. The casting temperature is within the range of 700±5℃, and the mold temperature is 150~200℃. After the alloy ingot is subjected to a low-temperature short-time aging treatment at 250℃×1h, the tensile strength is 118MPa, the yield strength is 69MPa, the elongation is 22.7%, and the electrical conductivity is 33.2MS / m.

[0039] Example 2

[0040] Please see Figure 1As shown, this invention provides an aluminum alloy technical solution for the rotor of an asynchronous motor in a new energy vehicle:

[0041] S1. Clean the smelting furnace thoroughly, add aluminum ingots and heat until melted. Spray the primary refining agent onto the surface of the melt, stir evenly, and let it stand for 10-20 minutes. After removing the slag, pour out the furnace wash charge a. The primary refining agent is a mixture of KCl, KBF4, and B4C. The ratio of the primary refining agent is: 25% KCl, 40% KBF4, and 20% B4C. The amount of primary refining agent added is 0.1-0.3% of the total mass of the alloy melt. The trace elements in furnace wash charge a are Mn: 0.002%, V: 0.005%, and Ti: 0.003%. The total amount of Mn+V+Ti elements is 0.01%.

[0042] All other steps and conditions are the same;

[0043] After undergoing a low-temperature short-time aging treatment at 250℃ for 1 hour, the alloy ingot exhibits a tensile strength of 132 MPa, a yield strength of 70 MPa, an elongation of 25.2%, and an electrical conductivity of 33.5 MS / m.

[0044] Example 3

[0045] Please see Figure 1 As shown, this invention provides an aluminum alloy technical solution for the rotor of an asynchronous motor in a new energy vehicle:

[0046] S3. Degas and perform secondary refining on alloy melt b. After degassing, let it stand for 20-30 minutes. After removing the slag, add the pre-proportioned B element to obtain alloy melt c. Set the degassing temperature to 720-730℃, the degassing medium to N2, and the secondary refining agent to a mixture of Na3AlF6, KCl, La2O3, and CeO2. The refining agent ratio is: 20% Na3AlF6, 20% KCl, 15% La2O3, and 10% Ce2O3. The amount of secondary refining agent added is 0.2%-0.3% of the total mass of the melt. The degassing time is 15-30 minutes. After degassing, let it stand for 20-30 minutes. After removing the slag, add the pre-proportioned B element, ensuring that the density of alloy melt c is ≥2.65 g / cm³. 3 The trace elements in melt c are Mn: 0.001%, V: 0.002%, and Ti: 0.001%, with the total amount of Mn+V+Ti being 0.004%, which does not exceed 0.02%.

[0047] All other steps are the same;

[0048] After undergoing a low-temperature short-time aging treatment at 250℃ for 1 hour, the alloy ingot exhibits a tensile strength of 140 MPa, a yield strength of 118 MPa, an elongation of 28%, and an electrical conductivity of 34.2 MS / m.

[0049] Example 4

[0050] Please see Figure 1 As shown, this invention provides an aluminum alloy technical solution for the rotor of an asynchronous motor in a new energy vehicle:

[0051] S3. Degas and perform secondary refining on alloy melt b. After degassing, let it stand for 20-30 minutes. After removing the slag, add the pre-proportioned B element to obtain alloy melt c. Set the degassing temperature to 720-730℃, the degassing medium to N2, and the secondary refining agent to a mixture of Na3AlF6, KCl, La2O3, and CeO2. The refining agent ratio is: 20% Na3AlF6, 20% KCl, 20% La2O3, and 10% Ce2O3. The amount of secondary refining agent added is 0.2%-0.3% of the total mass of the melt. The degassing time is 15-30 minutes. After degassing, let it stand for 20-30 minutes. During the standing process, set the melt temperature to 700℃-710℃. After removing the slag, add the pre-proportioned B element, ensuring that the density of alloy melt c is ≥2.65 g / cm³. 3 The trace elements in melt c are Mn: 0.001%, V: 0.002%, and Ti: 0.001%, with a total Mn+V+Ti element content of 0.004%, not exceeding 0.02%. The melt is stirred for 2-3 minutes and then immediately poured.

[0052] All other steps are the same;

[0053] After undergoing a low-temperature short-time aging treatment at 250℃ for 1 hour, the alloy ingot exhibits a tensile strength of 140 MPa, a yield strength of 64 MPa, an elongation of 27.5%, and an electrical conductivity of 33.6 MS / m.

[0054] Example 5

[0055] Please see Figure 1 As shown, this invention provides an aluminum alloy technical solution for the rotor of an asynchronous motor in a new energy vehicle:

[0056] S3. Degas and perform secondary refining on alloy melt b. After degassing, let it stand for 20-30 minutes. After removing the slag, add the pre-proportioned B element to obtain alloy melt c. Set the degassing temperature to 720-730℃, the degassing medium to N2, and the secondary refining agent to a mixture of Na3AlF6, KCl, La2O3, and CeO2. The refining agent ratio is: 20% Na3AlF6, 20% KCl, 20% La2O3, and 20% Ce2O3. The amount of secondary refining agent added is 0.2%-0.3% of the total mass of the melt. The degassing time is 15-30 minutes. After degassing, let it stand for 20-30 minutes. During the standing process, set the melt temperature to 700℃-710℃. After removing the slag, add the pre-proportioned B element, ensuring that the density of alloy melt c is ≥2.65 g / cm³. 3The melt c contains trace elements Mn: 0.001%, V: 0.002%, Ti: 0.001%, and the total amount of Mn+V+Ti is 0.004%. It is stirred for 2-3 minutes and then immediately cast.

[0057] All other steps are the same;

[0058] After undergoing a low-temperature short-time aging treatment at 250℃ for 1 hour, the alloy ingot exhibits a tensile strength of 160 MPa, a yield strength of 94 MPa, an elongation of 26.2%, and an electrical conductivity of 33.8 MS / m.

[0059] Comparative Example 1

[0060] The composition by mass percentage includes the following materials: 0.2-0.7 wt.% Fe, 1.5-2.5 wt.% Ni, 0.05-0.15 wt.% B, 0.005-0.1 wt.% Cr, Mn+V+Ti≤0.02 wt.%, with the balance being Al and impurities, the total impurity content not exceeding 0.02%; the mass ratio between Ni and Fe is 1.8≤Ni+Fe≤2.5, and the mass ratio between Ni and Fe is 5-10.

[0061] Preparation method:

[0062] S1. Clean the smelting furnace thoroughly, add aluminum ingots and heat until melted. Stir evenly and let stand for 10-20 minutes. After removing the slag, pour out the furnace wash charge a. The total amount of trace elements Mn+V+Ti in furnace wash charge a does not exceed 0.02%, and the total amount of impurities does not exceed 0.05 wt.%, Mn: 0.009%, V: 0.013%; Ti: 0.006%. The total amount of Mn+V+Ti is 0.028%.

[0063] S2. Add the Fe, Ni, and Cr raw materials according to the alloy composition ratio into the melting furnace in sequence, heat and melt them, and stir evenly to obtain alloy melt b. Add Fe, Ni, and Cr elements and Al at the same time, heat to above 760℃ until completely melted, adjust the temperature of the aluminum liquid to within the range of 720℃±5℃, stir thoroughly and let stand.

[0064] S3. Degas the alloy melt b. After degassing, let it stand for 20-30 minutes. After removing the slag, add the pre-proportioned B element to obtain alloy melt c. Set the degassing temperature to 720-730℃, the degassing medium to N2, and the degassing time to 15-30 minutes. After degassing, let it stand for 20-30 minutes. After removing the slag, add the pre-proportioned B element again. The trace elements in melt c are Mn: 0.009%, V: 0.013%, Ti: 0.006%, and the total amount of Mn+V+Ti elements is 0.028%.

[0065] S4. Pour the alloy melt c into a metal mold and cast it to obtain an alloy ingot. The casting temperature is within the range of 720±5℃, and the mold temperature is 150~200℃.

[0066] After undergoing a low-temperature short-time aging treatment at 250℃ for 1 hour, the alloy ingot exhibits a tensile strength of 110 MPa, a yield strength of 57 MPa, an elongation of 13.3%, and an electrical conductivity of 26.4 MS / m.

[0067] Comparative Example 2

[0068] S1. Clean the smelting furnace thoroughly, add aluminum ingots and heat until melted. Spray the primary refining agent onto the surface of the melt, stir evenly, and let it stand for 10-20 minutes. After removing the slag, pour out the furnace wash charge a. The primary refining agent is a mixture of KCl, KBF4, and B4C. The ratio of the primary refining agent is: 25% KCl, 40% KBF4, and 5% B4C. The amount of primary refining agent added is 0.1-0.3% of the total mass of the alloy melt. The trace elements in furnace wash charge a are Mn: 0.007%, V: 0.012%, and Ti: 0.005%. The total amount of Mn+V+Ti elements is 0.024%.

[0069] S3. Degas and perform secondary refining on alloy melt b. After degassing, let it stand for 20-30 minutes. After removing the slag, add the pre-proportioned B element to obtain alloy melt c. Set the degassing temperature to 720-730℃, the degassing medium to N2, and the secondary refining agent to a mixture of Na3AlF6, KCl, La2O3, and CeO2. The refining agent ratio is: 20% Na3AlF6, 20% KCl, 5% La2O3, and 10% Ce2O3. The amount of secondary refining agent added is 0.2%-0.3% of the total melt mass. The degassing time is 15-30 minutes. After degassing, let it stand for 20-30 minutes. After removing the slag, add the pre-proportioned B element, ensuring that the density of alloy melt c is ≥2.65 g / cm³. 3 The trace elements in melt c are Mn: 0.008%, V: 0.011%, and Ti: 0.004%, with a total Mn+V+Ti content of 0.023%.

[0070] All other steps are the same;

[0071] After undergoing a low-temperature short-time aging treatment at 250℃ for 1 hour, the alloy ingot exhibits tensile strength ≥110MPa, yield strength ≥60MPa, elongation ≥20%, and electrical conductivity ≥33MS / m.

[0072] Comparative Example 3

[0073] S1. Clean the smelting furnace thoroughly, add aluminum ingots and heat until melted. Spray the primary refining agent onto the surface of the melt, stir evenly, and let it stand for 10-20 minutes. After removing the slag, pour out the furnace wash charge a. The primary refining agent is a mixture of KCl, KBF4, and B4C. The ratio of the primary refining agent is: 25% KCl, 40% KBF4, and 22% B4C. The amount of primary refining agent added is 0.1-0.3% of the total mass of the alloy melt. The trace elements in furnace wash charge a are Mn: 0.008%, V: 0.012%, and Ti: 0.006%. The total amount of Mn+V+Ti elements is 0.024%.

[0074] S3. Degas and perform secondary refining on alloy melt b. After degassing, let it stand for 20-30 minutes. After removing the slag, add the pre-proportioned B element to obtain alloy melt c. Set the degassing temperature to 720-730℃, the degassing medium to N2, and the secondary refining agent to a mixture of Na3AlF6, KCl, La2O3, and CeO2. The refining agent ratio is: 20% Na3AlF6, 20% KCl, 23% La2O3, and 10% Ce2O3. The amount of secondary refining agent added is 0.2%-0.3% of the total mass of the melt. The degassing time is 15-30 minutes. After degassing, let it stand for 20-30 minutes. After removing the slag, add the pre-proportioned B element, ensuring that the density of alloy melt c is ≥2.65 g / cm³. 3 The trace elements in melt c are Mn: 0.008%, V: 0.012%; Ti: 0.005%, and the total amount of Mn+V+Ti is 0.025%.

[0075] All other steps are the same;

[0076] After undergoing a low-temperature short-time aging treatment at 250℃ for 1 hour, the alloy ingot exhibits a tensile strength of 134 MPa, a yield strength of 72 MPa, an elongation of 18.5%, and an electrical conductivity of 30.5 MS / m.

[0077] Comparative Example 4

[0078] S1. Clean the smelting furnace thoroughly, add aluminum ingots and heat until melted. Spray the primary refining agent onto the surface of the melt, stir evenly, and let it stand for 10-20 minutes. After removing the slag, pour out the furnace wash charge a. The primary refining agent is a mixture of KCl, KBF4, and B4C. The ratio of the primary refining agent is: 25% KCl, 40% KBF4, and 15% B4C. The amount of primary refining agent added is 0.1-0.3% of the total mass of the alloy melt. The trace elements in furnace wash charge a are Mn: 0.002%, V: 0.005%, and Ti: 0.002%. The total amount of Mn+V+Ti elements is 0.009%.

[0079] S3. Degas and perform secondary refining on alloy melt b. After degassing, let it stand for 20-30 minutes. After removing the slag, add the pre-proportioned B element to obtain alloy melt c. Set the degassing temperature to 720-730℃, the degassing medium to N2, and the secondary refining agent to a mixture of Na3AlF6, KCl, La2O3, and CeO2. The refining agent ratio is: 20% Na3AlF6, 20% KCl, 20% La2O3, and 8% Ce2O3. The amount of secondary refining agent added is 0.2%-0.3% of the total melt mass. The degassing time is 15-30 minutes. After degassing, let it stand for 20-30 minutes. After removing the slag, add the pre-proportioned B element, ensuring that the density of alloy melt c is ≥2.65 g / cm³. 3 The trace elements in melt c are Mn: 0.007%, V: 0.011%, and Ti: 0.004%, with a total Mn+V+Ti content of 0.022%.

[0080] All other steps are the same;

[0081] After undergoing a low-temperature short-time aging treatment at 250℃ for 1 hour, the alloy ingot exhibits a tensile strength of 123 MPa, a yield strength of 68 MPa, an elongation of 14.9%, and an electrical conductivity of 29.1 MS / m.

[0082] Comparative Example 5

[0083] S1. Clean the smelting furnace thoroughly, add aluminum ingots and heat until melted. Spray the primary refining agent onto the surface of the melt, stir evenly, and let it stand for 10-20 minutes. After removing the slag, pour out the furnace wash charge a. The primary refining agent is a mixture of KCl, KBF4, and B4C. The ratio of the primary refining agent is: 25% KCl, 40% KBF4, and 15% B4C. The amount of primary refining agent added is 0.1-0.3% of the total mass of the alloy melt. The trace elements in furnace wash charge a are Mn: 0.003%, V: 0.006%, and Ti: 0.003%. The total amount of Mn+V+Ti elements is 0.012%, not exceeding 0.02%.

[0084] S3. Degas and perform secondary refining on alloy melt b. After degassing, let it stand for 20-30 minutes. After removing the slag, add the pre-proportioned B element to obtain alloy melt c. Set the degassing temperature to 720-730℃, the degassing medium to N2, and the secondary refining agent to a mixture of Na3AlF6, KCl, La2O3, and CeO2. The refining agent ratio is: 20% Na3AlF6, 20% KCl, 20% La2O3. 3、 21% Ce₂O₃, secondary refining agent added at 0.2%~0.3% of the total melt mass, degassing time 15~30 min, stand for 20~30 min after degassing, remove slag before adding the pre-proportioned B element, and ensure that the carbon density of the alloy melt is ≥2.65 g / cm³.3 The trace elements in melt c are Mn: 0.006%, V: 0.0009%, and Ti: 0.006%, with a total Mn+V+Ti content of 0.021%.

[0085] All other steps are the same;

[0086] After undergoing a low-temperature short-time aging treatment at 250℃ for 1 hour, the alloy ingot exhibits a tensile strength of 149 MPa, a yield strength of 87 MPa, an elongation of 15.2%, and an electrical conductivity of 27.4 MS / m.

[0087] Comparative Example 6

[0088] S1. Clean the smelting furnace thoroughly, add aluminum ingots and heat until melted. Spray the primary refining agent onto the surface of the melt, stir evenly, and let it stand for 10-20 minutes. After removing the slag, pour out the furnace wash charge a. The primary refining agent is a mixture of KCl, KBF4, and B4C. The ratio of the primary refining agent is: 25% KCl, 40% KBF4, and 23% B4C. The amount of primary refining agent added is 0.1-0.3% of the total mass of the alloy melt. The trace elements in furnace wash charge a are Mn: 0.006%, V: 0.011%, and Ti: 0.005%. The total amount of Mn+V+Ti elements is 0.022%.

[0089] S3. Degas and perform secondary refining on alloy melt b. After degassing, let it stand for 20-30 minutes. After removing the slag, add the pre-proportioned B element to obtain alloy melt c. Set the degassing temperature to 720-730℃, the degassing medium to N2, and the secondary refining agent to a mixture of Na3AlF6, KCl, La2O3, and CeO2. The refining agent ratio is: 20% Na3AlF6, 20% KCl, and 23% La2O3. 3 、 21% Ce₂O₃, secondary refining agent added at 0.2%~0.3% of the total melt mass, degassing time 15~30 min, stand for 20~30 min after degassing, remove slag before adding the pre-proportioned B element, and ensure that the carbon density of the alloy melt is ≥2.65 g / cm³. 3 The trace elements in melt c are Mn: 0.009%, V: 0.013%, and Ti: 0.005%, with a total Mn+V+Ti content of 0.027%.

[0090] All other steps are the same;

[0091] After undergoing a low-temperature short-time aging treatment at 250℃ for 1 hour, the alloy ingot exhibits a tensile strength of 152 MPa, a yield strength of 86 MPa, an elongation of 16.8%, and an electrical conductivity of 26.7 MS / m.

[0092] The composition of the aluminum alloys and the addition of primary and secondary refining agents in Examples 1-5 and Comparative Examples 1-6 are shown in Table 1:

[0093]

[0094] Table 1

[0095] The contents of Mn, V, and Ti in the aluminum alloys after primary and secondary refining in Examples 1-5 and Comparative Examples 1-6, as well as the properties of the aluminum alloys, are shown in Table 2.

[0096]

[0097] Table 2

[0098] As shown in Tables 1 and 2, through two refining processes, the content of impurity elements such as Mn, Ti, and V can be effectively controlled below 0.02 wt.%, preventing the formation of coarse intermetallic phases (such as Al6(Mn,Fe), Al3V, Al3Ti, etc.) with the main alloying elements such as Al, Ni, and Fe. On the one hand, these phases are usually needle-like or blocky, disrupting the continuity of the matrix and leading to stress concentration; on the other hand, they interfere with the formation of the main strengthening phases in Al-Ni-Fe alloys, such as Al3Ni and Al9FeNi nanoprecipitates, thus increasing the electrical conductivity of the aluminum alloy. This ensures that the aluminum alloy has a tensile strength ≥110 MPa, a yield strength ≥60 MPa, an elongation ≥20%, and an electrical conductivity ≥33 MS / m. According to reference documents 1-6, when no refining process is performed, or when the composition of the refining agent exceeds the range, if Mn, Ti, and V exceed 0.02 wt.%, the elongation and electrical conductivity of the aluminum alloy will decrease, and it will be unable to meet the requirements of tensile strength ≥110 MPa, yield strength ≥60 MPa, elongation ≥20%, and electrical conductivity ≥33 MS / m.

[0099] The foregoing has shown and described the basic principles, main features, and advantages of the present invention. Those skilled in the art should understand that the present invention is not limited to the above embodiments. The embodiments and descriptions in the specification are merely preferred examples and are not intended to limit the invention. Various changes and modifications can be made to the invention without departing from its spirit and scope, and all such changes and modifications fall within the scope of the present invention as claimed. The scope of protection of the present invention is defined by the appended claims and their equivalents.

Claims

1. An aluminum alloy for the rotor of an asynchronous motor in a new energy vehicle, characterized in that: The composition by mass percentage includes the following materials: 0.2-0.7 wt.% Fe, 1.5-2.5 wt.% Ni, 0.05-0.15 wt.% B, 0.005-0.1 wt.% Cr, Mn+V+Ti≤0.02 wt.%, with the balance being Al and impurities, and the total impurity content not exceeding 0.02%. The specific steps in the preparation method of aluminum alloy for motor rotors are as follows: S1. Clean the smelting furnace, add aluminum ingots and heat until melted, spray the surface of the melt with a first-level refining agent, stir evenly and let stand for 10-20 minutes, remove the slag and pour out the furnace wash material a. S2. Add the Fe, Ni and Cr raw materials according to the alloy composition ratio into the melting furnace in sequence, heat and melt them, and stir evenly to obtain alloy melt b. S3. Degas and perform secondary refining on alloy melt b. After degassing, let it stand for 20-30 minutes. After removing the slag, add the proportioned B element to obtain alloy melt c. S4. Pour the alloy melt c into a metal mold, and after casting, obtain an alloy ingot; In step S1, the primary refining agent is a mixture of KCl, KBF4, and B4C, with a ratio of (30%) KCl + (50%) KBF4 + (20%) B4C. The amount of primary refining agent added is 0.1% to 0.3% of the total mass of the alloy melt. In step S3, the degassing temperature is set to 720~730℃, the degassing medium is N2, and the secondary refining agent is a mixture of Na3AlF6, KCl, La2O3, and CeO2. The refining agent ratio is (30%) Na3AlF6 + (30%) KCl + (20%) La2O3 + (20%) Ce2O3. The amount of secondary refining agent added is 0.2%~0.3% of the total melt mass. The degassing time is 15~30 min, and after degassing, the melt is allowed to stand for 20~30 min. During the standing process, the melt temperature is set to drop to 700℃-710℃. After slag removal, the proportioned B element is added, and the density of the alloy melt is ensured to be ≥2.65 g / cm³. 3 Stir for 2-3 minutes and then pour.

2. The aluminum alloy for an asynchronous motor rotor in a new energy vehicle according to claim 1, characterized in that: The mass relationship between Ni and Fe is as follows: 1.8 wt.% ≤ Ni + Fe ≤ 2.5 wt.%; The mass ratio of Ni to Fe is 5-10.

3. The aluminum alloy for an asynchronous motor rotor in a new energy vehicle according to claim 1, characterized in that: In step S1, the total amount of trace elements Mn+V+Ti in the furnace feed a does not exceed 0.02%wt., and the total amount of impurity elements does not exceed 0.05wt.

4. The aluminum alloy for an asynchronous motor rotor in a new energy vehicle according to claim 1, characterized in that: In step S2, Fe, Ni, Cr elements are added simultaneously with Al, and the mixture is heated to above 780°C until it is completely melted. Then, the temperature of the molten aluminum is adjusted to within the range of 720°C ± 5°C, and the mixture is stirred thoroughly before being allowed to stand.

5. The aluminum alloy for an asynchronous motor rotor in a new energy vehicle according to claim 1, characterized in that: In step S4, the casting temperature is within the range of 700±5℃, and the mold temperature is 150~200℃.

6. The aluminum alloy for an asynchronous motor rotor in a new energy vehicle according to claim 1, characterized in that: After undergoing a low-temperature short-time aging treatment at 250℃ for 1 hour, the alloy ingot exhibits a tensile strength ≥110MPa, a yield strength ≥60MPa, an elongation ≥20%, and an electrical conductivity ≥33MS / m.

7. The aluminum alloy for an asynchronous motor rotor in a new energy vehicle according to claim 1, characterized in that: The alloy ingot is suitable for the die-casting production process of motor rotors for new energy vehicles.

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