Cast aluminum alloy and preparation method therefor, motor rotor and automobile

Abstract

Provided in the present disclosure are a cast aluminum alloy and a preparation method therefor, a motor rotor and an automobile, which belong to the technical field of cast aluminum alloys. In one aspect, on the basis of the total mass of the cast aluminum alloy being 100 wt%, the cast aluminum alloy comprises the following components: 0.5-2 wt% of Fe, 0.1-1 wt% of Ni, 0.1-0.5 wt% of Mg, and the balance being Al and inevitable impurities. In another aspect, on the basis of the total mass of the cast aluminum alloy being 100 wt%, the cast aluminum alloy comprises the following components: 0.5-2 wt% of Fe, 0.3-1.5 wt% of Ni, 0.1-0.8 wt% of Cu, and the balance being Al and inevitable impurities.

Description

CROSS-REFERENCE TO RELATED APPLICATION

[0001] This application claims the priority to and benefits of Chinese Patent Application No. 202310449856.6, filed on April 24, 2023, and Chinese Patent Application No. 202310451120.2, filed on April 24, 2023, the entire contents of which are incorporated herein by reference.FIELD

[0002] The present disclosure relates to the technical field of cast aluminum alloys, and more particularly to a cast aluminum alloy and a preparation method therefor, a motor rotor and a vehicle.BACKGROUND

[0003] Vehicle motor rotors require cast aluminum alloys to have high electrical conductivity, and excellent mechanical properties and machinability. However, in practical applications, it is found that there is always a contradictory relationship between electrical conductivity and strength of aluminum alloys, that is, the electrical conductivity will decrease when the strength increases, and vice versa. In the related art, strategies on how to improve the electrical conductivity of the aluminum alloy and how to simultaneously maintain excellent mechanical properties are still very limited. Therefore, developing an aluminum alloy with high electrical conductivity and excellent mechanical properties is highly significant.

[0004] Since aluminum-silicon alloys have excellent castability, good mechanical properties and decent electrical conductivity, most aluminum alloys with high electrical conductivity and high strength currently in use are aluminum-silicon alloys. According to the related art [1], when a Si content in an aluminum alloy reaches 13%, an electrical conductivity of the aluminum alloy at room temperature is less than 40% IACS.

[0005] To address the above problems, electrical conductivity of aluminum alloys can be improved by selecting aluminum alloys to which Si is not added and instead alloying elements, such as Fe and Ni, are added, while ensuring that yield strength and tensile strength are not reduced too much. For example, the related art [2] discloses a silicon-free aluminum-iron-nickel alloy with high strength and high electrical conductivity, which includes 4.3 wt.% to 6 wt.% of Ni, 0.2 wt.% to 0.8 wt.% of Fe, 0.01 wt.% to 1 wt.% of Ti, and a balance of Al. The aluminum-iron-nickel alloy has an electrical conductivity of 40 to 50% IACS, a yield strength of not less than 90 MPa, and an ultimate tensile strength of 150 MPa. However, the aluminum-iron-nickel alloy still has the following problems: (1) Due to the high cost of nickel, alloys with high nickel content are more expensive to produce. Currently, for every 1 wt.% of Ni added during aluminum alloy smelting, the cost of aluminum ingots increases by 2,000 to 3,000 RMB / ton, which is not conducive to industrial production; (2) Due to its wide solidification temperature range, the aluminum-iron-nickel alloy is prone to forming coarse dendrites, making it difficult to compensate for the shrinkage of alloy liquid, and readily resulting in a reduction in microstructural density. [1] K. N. Prahbu and B. N. Ravishankar. 2003. Mater. Sci. Eng. A. [J]. Effect of Modification Melt Treatment on Casting / Chill Interfacial Heat Transfer and Electrical Conductivity of Al-13 % Si Alloy. 360: 293-298. [2] Patent Application HK40042796A, Aluminum alloy for die casting. SUMMARY

[0006] The present disclosure is intended to solve at least one of the technical problems in the related art to some extent. To this end, embodiments of the present disclosure provide a cast aluminum alloy for a motor rotor and a preparation method therefor, a motor rotor, and a vehicle. The cast aluminum alloy has a relatively low cost, and has both improved electrical conductivity and improved strength.

[0007] In a first aspect, embodiments of the present disclosure provide a cast aluminum alloy for a motor rotor. The cast aluminum alloy includes 0.5 to 2 wt.% of Fe, 0.1 to 1 wt.% of Ni, 0.1 to 0.5 wt.% of Mg, and a balance of Al and inevitable impurities, based on a total mass of 100 wt.% of the cast aluminum alloy.

[0008] Advantages and technical effects of the cast aluminum alloy for the motor rotor according to embodiments of the present disclosure are as follows: (1) In the present disclosure, elements, such as Fe and Ni, that can improve strength of aluminum alloys are added to the cast aluminum alloy. Therefore, the cast aluminum alloy can greatly improve electrical conductivity while ensuring that yield strength and tensile strength are not reduced too much; (2) The cast aluminum alloy according to embodiments of the present disclosure includes Mg. Mg dissolves in a matrix α-Al phase, providing solid solution strengthening, and acting in concert with a (Fe,Ni) 4 Al 13 phase of the matrix, so that the cast aluminum alloy has good yield strength and tensile strength; (3) Compared with cast aluminum alloys disclosed in the related art, a Ni content in the cast aluminum alloy according to embodiments of the present disclosure is relatively low, and no heat treatment is required. Therefore, the cost of the cast aluminum alloy obtained is relatively low.

[0009] In some embodiments, the cast aluminum alloy includes 0.5 to 1.5 wt.% of Fe, 0.5 to 1 wt.% of Ni, 0.1 to 0.35 wt.% of Mg, and a balance of Al and inevitable impurities, with a content of a single impurity of ≤ 0.05 wt.%, and a total impurity content of ≤ 0.15 wt.%, based on a total mass of 100 wt.% of the cast aluminum alloy.

[0010] In some embodiments, a total content of Fe and Ni is in a range of 2 to 2.5 wt.%.

[0011] In some embodiments, a mole fraction of a (Fe,Ni) 4 Al 13 phase in the cast aluminum alloy is in a range of 4 to 6 mol%.

[0012] In some embodiments, the cast aluminum alloy has a room temperature electrical conductivity of 50% IACS or more.

[0013] In some embodiments, the cast aluminum alloy has a yield strength of 65 MPa or more.

[0014] In some embodiments, the cast aluminum alloy has a tensile strength of 150 MPa or more.

[0015] In some embodiments, the cast aluminum alloy has a porosity of 0.3% or less.

[0016] In some embodiments, the cast aluminum alloy has an elongation of 14% or more.

[0017] In a second aspect, embodiments of the present disclosure further provide a cast aluminum alloy for a motor rotor. The cast aluminum alloy includes 0.5 to 2 wt.% of Fe, 0.3 to 1.5 wt.% of Ni, 0.1 to 0.8 wt.% of Cu, and a balance of Al and inevitable impurities, based on a total mass of 100 wt.% of the cast aluminum alloy.

[0018] Advantages and technical effects of the cast aluminum alloy according to embodiments of the present disclosure are as follows: (1) The cast aluminum alloy according to embodiments of the present disclosure includes no Si that reduces electrical conductivity of aluminum alloys, but includes elements, such as Fe and Ni, that can improve strength of aluminum alloys. Therefore, the cast aluminum alloy can improve electrical conductivity while ensuring that yield strength and tensile strength are not reduced too much; (2) The cast aluminum alloy according to embodiments of the present disclosure includes Cu. Cu dissolves in a matrix α-Al phase, providing solid solution strengthening, and acting in concert with a (Fe,Ni) 4 Al 13 phase of the matrix, so that the cast aluminum alloy has excellent yield strength and tensile strength; (3) Compared with cast aluminum alloys disclosed in the related art, a Ni content in the cast aluminum alloy according to embodiments of the present disclosure is relatively low. Therefore, the cost of the cast aluminum alloy obtained is relatively low.

[0019] In some embodiments, the cast aluminum alloy includes 1 to 1.5 wt.% of Fe, 0.3 to 1 wt.% of Ni, 0.1 to 0.6 wt.% of Cu, and a balance of Al and inevitable impurities, with a content of a single impurity of ≤ 0.05 wt.%, and a total impurity content of ≤ 0.15 wt.%, based on a total mass of 100 wt.% of the cast aluminum alloy.

[0020] In some embodiments, a total content of Fe and Ni is in a range of 0.8 to 3 wt.%.

[0021] In some embodiments, the total content of Fe and Ni is in a range of 2 to 2.5 wt.%.

[0022] In some embodiments, the cast aluminum alloy has a room temperature electrical conductivity of 47% IACS or more.

[0023] In some embodiments, the cast aluminum alloy has a porosity of 0.1% or less.

[0024] In some embodiments, the cast aluminum alloy has an elongation of 13% or more.

[0025] In the third aspect, embodiments of the present disclosure further provide a method for preparing a cast aluminum alloy for a motor rotor. The method includes adding raw materials of the aluminum alloy in proportion, and smelting the raw materials of the aluminum alloy to obtain an aluminum alloy melt, and refining and degassing the aluminum alloy melt, followed by casting the aluminum alloy melt into a casting mold to obtain the cast aluminum alloy.

[0026] Advantages and technical effects of the method for preparing the cast aluminum alloy for the motor rotor according to embodiments of the present disclosure are as follows: (1) The preparation method according to embodiments of the present disclosure has simple steps and is suitable for industrial-scale application; (2) The cast aluminum alloy obtained by the preparation method according to embodiments of the present disclosure not only has a relatively low cost, but also can maintain electrical conductivity and mechanical properties at the same time.

[0027] In some embodiments, the casting mold is not preheated and maintained at room temperature.

[0028] In some embodiments, no heat treatment is performed after the cast aluminum alloy is obtained.

[0029] In some embodiments, the preparation method includes preheating a pit furnace in an empty state at a preheating temperature of 400 °C or above to remove moisture from the pit furnace, and preheating pure aluminum; placing preheated pure aluminum into the pit furnace for smelting at a smelting temperature of 780 to 800 °C; skimming off surface slag and oxide scale after the pure aluminum is completely melted, and maintaining a melt temperature; adding pure iron, pure nickel and pure magnesium, or adding an aluminum-iron master alloy, an aluminum-nickel master alloy and an aluminum-magnesium master alloy, completely submerging the raw materials of the aluminum alloy into aluminum liquid, and completely melting the raw materials of the aluminum alloy, following by standing for 2 to 3 h to obtain the aluminum alloy melt; wrapping a refining agent with aluminum foil and drying the refining agent, and preheating a stainless steel bell; pressing the refining agent preheated to a bottom of the aluminum alloy melt with the stainless steel bell preheated; introducing high-purity argon gas into the aluminum alloy melt, and refining and degassing the aluminum alloy melt; casting the aluminum alloy melt into the casting mold while maintaining a casting temperature of 700 to 740 °C; and opening the casting mold to obtain the cast aluminum alloy after an aluminum-iron-nickel alloy melt solidifies and cools.

[0030] In a fourth aspect, embodiments of the present disclosure further provide a motor rotor, which is prepared from the cast aluminum alloy according to embodiments of the present disclosure.

[0031] Advantages and technical effects of the motor rotor according to embodiments of the present disclosure are as follows: Since the motor rotor according to embodiments of the present disclosure is prepared from the cast aluminum alloy according to embodiments of the present disclosure, an electronic rotor will not fail even at a rotational speed as high as 18,000 rpm.

[0032] In a fifth aspect, embodiments of the present disclosure further provide a vehicle, which includes the motor rotor according to embodiments of the present disclosure.

[0033] Advantages and technical effects of the vehicle according to embodiments of the present disclosure are as follows: Due to the use of the motor rotor according to embodiments of the present disclosure, the vehicle according to embodiments of the present disclosure accelerates faster and can match relatively high rotational speeds and relatively high energy efficiency levels.BRIEF DESCRIPTION OF THE DRAWINGS

[0034] FIG. 1 is an SEM image of a cast aluminum alloy according to Example 1; FIG. 2 is an SEM image of a cast aluminum alloy according to Example 10. DETAILED DESCRIPTION

[0035] Embodiments of the present disclosure are described in detail below, examples of which are illustrated in the accompanying drawings. The embodiments described below with reference to the accompanying drawings are illustrative, and are intended to explain the present disclosure and cannot be construed as limiting the present disclosure.

[0036] In a first aspect, embodiments of the present disclosure provide a cast aluminum alloy for a motor rotor. The cast aluminum alloy includes 0.5 to 2 wt.% of Fe, 0.1 to 1 wt.% of Ni, 0.1 to 0.5 wt.% of Mg, and a balance of Al and inevitable impurities, based on a total mass of 100 wt.% of the cast aluminum alloy.

[0037] Since the cast aluminum alloy according to embodiments of the present disclosure includes no Si, it has excellent electrical conductivity compared with a cast aluminum alloy with high Si content in the related art. Although the absence of element Si may reduce strength of the cast aluminum alloy, since the cast aluminum alloy includes elements Fe, Ni and Mg, main phases of the cast aluminum alloy include a primary (Fe,Ni) 4 Al 13 phase, an α-Al phase, and a (Fe,Ni) 4 Al 13 and α-Al eutectic phase. The (Fe,Ni) 4 Al 13 phase has an effect of improving yield strength and tensile strength of the aluminum alloy. Moreover, element Mg does not form compounds with elements Fe and Ni, but dissolves in the matrix α-Al phase, providing solid solution strengthening, which further improves the yield strength and the tensile strength of the aluminum alloy. Therefore, the cast aluminum alloy can have good yield strength and tensile strength while maintaining excellent electrical conductivity. In addition, compared with the cast aluminum alloy with high Ni content in the related art, a Ni content in the cast aluminum alloy according to embodiments of the present disclosure is relatively low, and thus the cost of the cast aluminum alloy obtained is relatively low, which is beneficial for enterprises to reduce production costs.

[0038] In the cast aluminum alloy according to embodiments of the present disclosure, a mass fraction of Fe is in a range of 0.5 to 2 wt.%, for example, 0.5 wt.%, 0.8 wt.%, 1 wt.%, 1.2 wt.%, 1.4 wt.%, 1.6 wt.%, 1.8 wt.%, 2 wt.%, etc., and a mass fraction of Ni is in a range of 0.1 to 1 wt.%, for example, 0.1 wt.%, 0.3wt.%, 0.5 wt.%, 0.7 wt.%, 1.0 wt.%, etc., based on a total mass of 100 wt.% of the cast aluminum alloy. When the mass fraction of Fe is less than 0.5 wt.% and the mass fraction of Ni is less than 0.1 wt.%, it is difficult to form a sufficient amount of (Fe,Ni) 4 Al 13 phase, resulting in relatively low yield strength and tensile strength of the cast aluminum alloy. When the mass fraction of Fe is higher than 2 wt.%, an excessive amount of (Fe,Ni) 4 Al 13 phase forms, resulting in a decrease in electrical conductivity of the cast aluminum alloy. When the mass fraction of Ni is higher than 1 wt.%, the cost of the cast aluminum alloy increases correspondingly due to the high cost of Ni. Preferably, the mass fraction of Fe is in a range of 0.5 to 1.5 wt.%, and the mass fraction of Ni is in a range of 0.5 to 1 wt.%.

[0039] In the cast aluminum alloy according to embodiments of the present disclosure, a mass fraction of Mg is in a range of 0.1 to 0.5 wt.%, for example, 0.1 wt.%, 0.2 wt.%, 0.3 wt.%, 0.4 wt.%, 0.5 wt.%, etc., based on a total mass of 100 wt.% of the cast aluminum alloy. When the mass fraction of Mg is less than 0.1 wt.%, it fails to provide solid solution strengthening, thus significantly reducing both the yield strength and tensile strength of the cast aluminum alloy. When the mass fraction of Mg is higher than 0.5 wt.%, the electrical conductivity of the cast aluminum alloy decreases. Preferably, the mass fraction of Mg is in a range of 0.1 to 0.35 wt.%.

[0040] In some embodiments, a content of a single impurity is in a range of ≤ 0.05 wt.%, and a total impurity content is in a range of ≤ 0.15 wt.%. The impurity content complies with requirements of standard GB / T 8733-2016.

[0041] In some embodiments, a total content of Fe and Ni is in a range of 0.6 to 3 wt.%, for example, 0.6 wt.%, 0.8 wt.%, 1 wt.%, 1.2 wt.%, 1.4 wt.%, 1.6 wt.%, 1.8 wt.%, 2 wt.%, 2.2 wt.%, 2.4 wt.%, 2.6 wt.%, 2.8 wt.%, 3 wt.%, etc. Compared with the cast aluminum alloy with high Ni content in the related art, the cast aluminum alloy according to embodiments of the present disclosure has a relatively low Ni content, and thus the total content of Fe and Ni is relatively low. On the one hand, it can narrow a solidification temperature range of the cast aluminum alloy, reduce its susceptibility to shrinkage porosity and hot cracking, decrease porosity, and improve density of the cast aluminum alloy, thus improving castability of the cast aluminum alloy. On the other hand, it can reduce a content of a coarse (Fe,Ni) 4 Al 13 phase, improving elongation of the cast aluminum alloy, and allowing the cast aluminum alloy to absorb more energy without fracturing upon impact. Moreover, reducing the content of the coarse (Fe,Ni) 4 Al 13 phase can improve the electrical conductivity of the cast aluminum alloy. Preferably, the total content of Fe and Ni is in a range of 2 to 2.5 wt.%.

[0042] In some embodiments, a mole fraction of a (Fe,Ni) 4 Al 13 phase in the cast aluminum alloy is in a range of 4 to 6 mol%. The (Fe,Ni) 4 Al 13 phase exists as a primary phase and also forms in a final eutectic portion during solidification. The eutectic portion forms at a final stage of solidification via melt → α-Al+(Fe,Ni) 4 Al 13 , and (Fe,Ni) 4 Al 13 particles of the eutectic portion are fine and uniform, which is beneficial to reduce the influence on elongation. When a content of the (Fe,Ni) 4 Al 13 phase in the cast aluminum alloy is less than 4 mol%, it is not conducive to improving the yield strength and tensile strength of the cast aluminum alloy. When a content of the (Fe,Ni) 4 Al 13 phase in the cast aluminum alloy is higher than 6 mol%, it is not conducive to improving the elongation of the cast aluminum alloy.

[0043] In some embodiments, the cast aluminum alloy has a room temperature electrical conductivity of 50% IACS or more, preferably in a range of 50 to 53% IACS, for example, 50% IACS, 50.5% IACS, 51% IACS, 51.5% IACS, 52% IACS, 52.5% IACS, 53% IACS, etc.

[0044] In some embodiments, the cast aluminum alloy has a yield strength of 65 MPa or more, preferably in a range of 65 to 80 MPa, for example, 65 MPa, 68 MPa, 70 MPa, 73MPa, 75 MPa, 78 MPa, 80 MPa, etc.

[0045] In some embodiments, the cast aluminum alloy has a tensile strength of 150 MPa or more, preferably in a range of 150 to 170 MPa, for example, 150 MPa, 153 MPa, 155 MPa, 158 MPa, 160 MPa, 163 MPa, 165 MPa, 168 MPa, 170 MPa, etc.

[0046] In some embodiments, the cast aluminum alloy has a porosity of 0.3% or less, preferably in a range of 0.01 to 0.3%, for example, 0.01%, 0.05%, 0.1%, 0.15%, 0.18%, 0.2%, 0.23%, 0.25%, 0.3%, etc.

[0047] In some embodiments, the cast aluminum alloy has an elongation of 14% or more, preferably in a range of 14 to 22%, for example, 14%, 15%, 16%, 17%, 18%, 19%, 20%, 21%, 22%, etc.

[0048] In a second aspect, embodiments of the present disclosure provide a cast aluminum alloy for a motor rotor. The cast aluminum alloy includes 0.5 to 2 wt.% of Fe, 0.3 to 1.5 wt.% of Ni, 0.1 to 0.8 wt.% of Cu, and a balance of Al and inevitable impurities, based on a total mass of 100 wt.% of the cast aluminum alloy.

[0049] Since the cast aluminum alloy according to embodiments of the present disclosure includes no Si, electrical conductivity of the cast aluminum alloy is significantly improved compared with a cast aluminum alloy containing Si in the related art. Although the absence of element Si may reduce strength of the cast aluminum alloy, since the cast aluminum alloy includes elements Fe, Ni and Cu, main phases of the cast aluminum alloy include a primary (Fe,Ni) 4 Al 13 phase, an α-Al phase, and a (Fe,Ni) 4 Al 13 and α-Al eutectic phase. The (Fe,Ni) 4 Al 13 phase can improve yield strength and tensile strength of the aluminum alloy. Moreover, Cu does not form compounds with elements Fe and Ni, but dissolves in the matrix α-Al phase, providing solid solution strengthening, which further improves the yield strength and the tensile strength of the aluminum alloy. Therefore, the cast aluminum alloy can have excellent yield strength and tensile strength while maintaining good electrical conductivity. In addition, compared with the cast aluminum alloy with high Ni content in the related art, a Ni content in the cast aluminum alloy according to embodiments of the present disclosure is relatively low, and thus the cost of the cast aluminum alloy obtained is relatively low, which is beneficial for enterprises to reduce production costs. The cast aluminum alloy according to embodiments of the present disclosure is suitable for preparing high-strength, high-electrical conductivity components, such as motor rotors for new energy vehicles.

[0050] In the cast aluminum alloy according to embodiments of the present disclosure, a mass fraction of Fe is in a range of 0.5 to 2 wt.%, for example, 0.5 wt.%, 0.8 wt.%, 1 wt.%, 1.2 wt.%, 1.4 wt.%, 1.6 wt.%, 1.8 wt.%, 2 wt.%, etc., and a mass fraction of Ni is in a range of 0.3 to 1.5 wt.%, for example, 0.3wt.%, 0.5 wt.%, 0.8 wt.%, 1 wt.%, 1.2 wt.%, 1.5 wt.%, etc., based on a total mass of 100 wt.% of the cast aluminum alloy. When the mass fraction of Fe is less than 0.5 wt.% and the mass fraction of Ni is less than 0.3 wt.%, it is difficult to form a sufficient amount of (Fe,Ni) 4 Al 13 phase, resulting in relatively low yield strength and tensile strength of the cast aluminum alloy. When the mass fraction of Fe is higher than 2 wt.%, an excessive amount of (Fe,Ni) 4 Al 13 phase forms, resulting in a decrease in electrical conductivity of the cast aluminum alloy. When the mass fraction of Ni is higher than 1.5 wt.%, the cost of the cast aluminum alloy increases correspondingly due to the high cost of Ni. Preferably, the mass fraction of Fe is in a range of 1 to 1.5 wt.%, and the mass fraction of Ni is in a range of 0.3 to 1 wt.%.

[0051] In the cast aluminum alloy according to embodiments of the present disclosure, a mass fraction of Cu is in a range of 0.1 to 0.8 wt.%, for example, 0.1 wt.%, 0.2 wt.%, 0.3 wt.%, 0.4 wt.%, 0.5 wt.%, 0.6 wt.%, 0.7 wt.%, 0.8 wt.%, etc., based on a total mass of 100 wt.% of the cast aluminum alloy. When the mass fraction of Cu is less than 0.1 wt.%, it fails to provide solid solution strengthening, thus significantly reducing both the yield strength and tensile strength of the cast aluminum alloy. When the mass fraction of Cu is higher than 0.8 wt.%, the electrical conductivity of the cast aluminum alloy decreases. Preferably, the mass fraction of Cu is in a range of 0.1 to 0.6 wt.%.

[0052] In some embodiments, a total content of Fe and Ni is in a range of 0.8 to 3 wt.%, for example, 0.8 wt.%, 1 wt.%, 1.2 wt.%, 1.4 wt.%, 1.6 wt.%, 1.8 wt.%, 2 wt.%, 2.2 wt.%, 2.4 wt.%, 2.6 wt.%, 2.8 wt.%, 3 wt.%, etc. Compared with the cast aluminum alloy with high Ni content in the related art, the cast aluminum alloy according to embodiments of the present disclosure has a relatively low Ni content, and thus the total content of Fe and Ni is relatively low. On the one hand, it can narrow a solidification temperature range of the cast aluminum alloy, reduce its susceptibility to shrinkage porosity and hot cracking, decrease porosity, and improve density of the cast aluminum alloy, thus improving castability of the cast aluminum alloy. On the other hand, it can reduce a content of a coarse (Fe,Ni) 4 Al 13 phase, improving elongation of the cast aluminum alloy, and allowing the cast aluminum alloy to absorb more energy without fracturing upon impact. Moreover, reducing the content of the coarse (Fe,Ni) 4 Al 13 phase can improve the electrical conductivity of the cast aluminum alloy. Preferably, the total content of Fe and Ni is in a range of 2 to 2.5 wt.%.

[0053] In some embodiments, a content of a single impurity is in a range of ≤ 0.05 wt.%, and a total impurity content is in a range of ≤ 0.15 wt.%. The impurity content complies with requirements of standard GB / T 8733-2016.

[0054] In some embodiments, the cast aluminum alloy has a room temperature electrical conductivity of 47% IACS or more, preferably in a range of 47 to 52% IACS, for example, 47% IACS, 48% IACS, 49% IACS, 50% IACS, 51% IACS, 52% IACS, etc.

[0055] In some embodiments, the cast aluminum alloy has a yield strength of 75 MPa or more, preferably in a range of 75 to 100 MPa, for example, 75 MPa, 80 MPa, 85 MPa, 90 MPa, 95 MPa, 100 MPa, etc.

[0056] In some embodiments, the cast aluminum alloy has a tensile strength of 160 MPa or more, preferably in a range of 160 to 190 MPa, for example, 160 MPa, 165 MPa, 170 MPa, 175 MPa, 180 MPa, 185 MPa, 190 MPa, etc.

[0057] In some embodiments, the cast aluminum alloy has a porosity of 0.1% or less, preferably in a range of 0.01 to 0.1%, for example, 0.01%, 0.02%, 0.03%, 0.04%, 0.05%, 0.06%, 0.07%, 0.08%, 0.09%, 0.1%, etc.

[0058] In some embodiments, the cast aluminum alloy has an elongation of 13% or more, more preferably in a range of 13 to 20%, for example, 13%, 14%, 15%, 16%, 17%, 18%, 19%, 20%, etc.

[0059] In a third aspect, embodiments of the present disclosure further provide a method for preparing a cast aluminum alloy for a motor rotor. The method includes steps as follows: Smelting of aluminum alloy melt: adding raw materials of the aluminum alloy in proportion, and smelting the raw materials of the aluminum alloy to obtain an aluminum alloy melt; and Preparation of cast aluminum alloy: refining and degassing the aluminum alloy melt, followed by casting the aluminum alloy melt into a casting mold to obtain the cast aluminum alloy.

[0060] The preparation method according to embodiments of the present disclosure has simple steps, and is suitable for industrial-scale application. The cast aluminum alloy obtained not only has a relatively low cost, but also can maintain electrical conductivity and mechanical properties at the same time.

[0061] In some embodiments, the aluminum alloy melt refined and degassed is cast into the casting mold that is not preheated and maintained at room temperature. Compared with a manner of preheating the casting mold, a manner of no preheating the casting mold increases a temperature gradient between the aluminum alloy melt and the casting mold, thus increasing a cooling rate, which is beneficial to improve electrical conductivity, yield strength, tensile strength and elongation of the cast aluminum alloy.

[0062] In some embodiments, no heat treatment is performed after the cast aluminum alloy is obtained. Compared with performing heat treatment after obtaining the cast aluminum alloy, performing no heat treatment can significantly improve yield strength and tensile strength of the cast aluminum alloy. If heat treatment is performed, casting internal stress of the aluminum alloy will be released, and a decrease in casting internal stress will lead to a decrease in strength. In addition, performing no heat treatment can greatly reduce energy consumption, optimize processes, reduce industrial production costs and improve economic benefits.

[0063] In some embodiments, the smelting of aluminum alloy melt specifically includes preheating a pit furnace in an empty state at a preheating temperature of 400 °C or above to remove moisture from the pit furnace, and preheating pure aluminum, placing preheated pure aluminum into the pit furnace for smelting at a smelting temperature of 780 to 800 °C, skimming off surface slag and oxide scale after the pure aluminum is completely melted, and maintaining a melt temperature, adding pure iron, pure nickel and pure magnesium, or adding an aluminum-iron master alloy, an aluminum-nickel master alloy and an aluminum-magnesium master alloy, or adding pure iron, pure nickel and pure copper, completely submerging the raw materials of the aluminum alloy into aluminum liquid, and completely melting alloying elements, following by standing for 2 to 3 h to obtain the aluminum alloy melt.

[0064] In some embodiments, the preparation of cast aluminum alloy specifically includes wrapping a refining agent with aluminum foil and drying the refining agent, and preheating a stainless steel bell, pressing the refining agent preheated to a bottom of the aluminum alloy melt with the stainless steel bell preheated, introducing high-purity argon gas into the aluminum alloy melt, and refining and degassing the aluminum alloy melt, casting the aluminum alloy melt into the casting mold that is not preheated and maintained at room temperature while maintaining a casting temperature of 700 to 740 °C, and opening the casting mold to obtain the cast aluminum alloy after the aluminum alloy melt solidifies and cools. The casting mold is made of cast iron, and a casting time is controlled within 30s.

[0065] In a fourth aspect, embodiments of the present disclosure further provide a motor rotor, which is prepared from the cast aluminum alloy according to embodiments of the present disclosure.

[0066] Since the motor rotor according to embodiments of the present disclosure is prepared from the cast aluminum alloy according to embodiments of the present disclosure, an electronic rotor will not fail even at a rotational speed as high as 18,000 rpm.

[0067] In a fifth aspect, embodiments of the present disclosure further provide a vehicle, which includes the motor rotor according to embodiments of the present disclosure and can match relatively high rotational speeds and relatively high energy efficiency levels.

[0068] Due to the use of the motor rotor according to embodiments of the present disclosure, the vehicle according to embodiments of the present disclosure accelerates faster.

[0069] The present disclosure will be described in detail below with reference to examples and accompanying drawings.Example 1

[0070] A cast aluminum alloy for a motor rotor included 1.5 wt.% of Fe, 1 wt.% of Ni, 0.3 wt.% of Mg, and a balance of Al and inevitable impurities, with a content of a single impurity of ≤ 0.05 wt.%, and a total impurity content of ≤ 0.15 wt.%, based on a total mass of 100 wt.% of the cast aluminum alloy.

[0071] A method for preparing the cast aluminum alloy included steps as follows: Smelting of aluminum alloy melt: preheating a pit furnace in an empty state at a preheating temperature of 400 °C to remove moisture from the pit furnace, and preheating pure aluminum; placing preheated pure aluminum into the pit furnace for smelting at a smelting temperature of 780 to 800 °C, skimming off surface slag and oxide scale after the pure aluminum was completely melted, and maintaining a melt temperature; adding pure iron, pure nickel and pure magnesium, completely submerging the pure iron, the pure nickel and the pure magnesium into aluminum liquid, and completely melting alloying elements, following by standing for 2 h to obtain the aluminum alloy melt; Preparation of cast aluminum alloy: wrapping a refining agent with aluminum foil and drying the refining agent, and preheating a stainless steel bell, pressing the refining agent preheated to a bottom of the aluminum alloy melt with the stainless steel bell preheated, introducing high-purity argon gas into the aluminum alloy melt, and refining and degassing the aluminum alloy melt; casting the aluminum alloy melt into a casting mold that was not preheated and maintained at room temperature while maintaining a casting temperature of 700 to 740 °C, and opening the casting mold to obtain the cast aluminum alloy after the aluminum alloy melt solidified and cooled. The casting mold was made of cast iron, and a casting time was to be controlled within 30s. Example 2

[0072] The alloy composition and preparation method were the same as those in Example 1, with the only difference being that after step S2, a T6 heat treatment was further performed. The cast aluminum alloy obtained in step S2 was subjected to a solution treatment at 520°C for 4 h, taken out for water quenching, subjected to an aging treatment at 180°C for 3 h, and after completion, taken out for air cooling, with an interval between the solution treatment and the aging treatment not exceeding 0.5 h.Example 3

[0073] A cast aluminum alloy for a motor rotor included 1 wt.% of Fe, 1 wt.% of Ni, 0.3 wt.% of Mg, and a balance of Al and inevitable impurities, with a content of a single impurity of ≤ 0.05 wt.%, and a total impurity content of ≤ 0.15 wt.%, based on a total mass of 100 wt.% of the cast aluminum alloy.

[0074] A method for preparing the cast aluminum alloy was the same as that in Example 1.Example 4

[0075] The alloy composition and preparation method were the same as those in Example 2, with the only difference being that after step S2, a T6 heat treatment was further performed. The cast aluminum alloy obtained in step S2 was subjected to a solution treatment at 520°C for 4 h, taken out for water quenching, subjected to an aging treatment at 180°C for 3 h, and after completion, taken out for air cooling, with an interval between the solution treatment and the aging treatment not exceeding 0.5 h.Example 5

[0076] The alloy composition and preparation method were the same as those in Example 3, with the only difference being that the casting mold was preheated to 150°C, and the aluminum alloy melt refined and degassed was cast into this casting mold.Example 6

[0077] A cast aluminum alloy for a motor rotor included 2 wt.% of Fe, 1 wt.% of Ni, 0.3 wt.% of Mg, and a balance of Al and inevitable impurities, with a content of a single impurity of ≤ 0.05 wt.%, and a total impurity content of ≤ 0.15 wt.%, based on a total mass of 100 wt.% of the cast aluminum alloy.

[0078] A method for preparing the cast aluminum alloy was the same as that in Example 1, with the only difference being that in step S1, pure iron, pure nickel and pure magnesium, or aluminum-based master alloys (which may be Al-Fe, Al-Ni and Al-Mg) were added, and were completely submerged into aluminum liquid.Example 7

[0079] A cast aluminum alloy for a motor rotor included 1.6 wt.% of Fe, 0.8 wt.% of Ni, 0.15 wt.% of Mg, and a balance of Al and inevitable impurities, with a content of a single impurity of ≤ 0.05 wt.%, and a total impurity content of ≤ 0.15 wt.%, based on a total mass of 100 wt.% of the cast aluminum alloy.

[0080] A method for preparing the cast aluminum alloy was the same as that in Example 1.Example 8

[0081] A cast aluminum alloy included 1 wt.% of Fe, 1 wt.% of Ni, 0.6 wt.% of Cu, and a balance of Al and inevitable impurities, with a content of a single impurity of ≤ 0.05 wt.%, and a total impurity content of ≤ 0.15 wt.%, based on a total mass of 100 wt.% of the cast aluminum alloy.

[0082] A method for preparing the cast aluminum alloy included steps as follows: Smelting of aluminum alloy melt: preheating a pit furnace in an empty state at a preheating temperature of 400 °C to remove moisture from the pit furnace, and preheating pure aluminum; placing preheated pure aluminum into the pit furnace for smelting at a smelting temperature of 780 to 800 °C, skimming off surface slag and oxide scale after the pure aluminum was completely melted, and maintaining a melt temperature; adding pure iron, pure nickel and pure copper, completely submerging the pure iron, the pure nickel and the pure copper into aluminum liquid, and completely melting alloying elements, following by standing for 2 h to obtain the aluminum alloy melt; Preparation of cast aluminum alloy: wrapping a refining agent with aluminum foil and drying the refining agent, and preheating a stainless steel bell; pressing the refining agent preheated to a bottom of the aluminum alloy melt with the stainless steel bell preheated, introducing high-purity argon gas into the aluminum alloy melt, and refining and degassing the aluminum alloy melt; casting the aluminum alloy melt into a casting mold that was not preheated and maintained at room temperature while maintaining a casting temperature of 700 to 740 °C, and opening the casting mold to obtain the cast aluminum alloy after the aluminum alloy melt solidified and cooled. The casting mold was made of cast iron, and a casting time was controlled within 30s. Example 9

[0083] A cast aluminum alloy included 1.5 wt.% of Fe, 1 wt.% of Ni, 0.6 wt.% of Cu, and a balance of Al and inevitable impurities, with a content of a single impurity of ≤ 0.05 wt.%, and a total impurity content of ≤ 0.15 wt.%, based on a total mass of 100 wt.% of the cast aluminum alloy.

[0084] A method for preparing the cast aluminum alloy was the same as that in Example 8.Example 10

[0085] A cast aluminum alloy included 2 wt.% of Fe, 1 wt.% of Ni, 0.6 wt.% of Cu, and a balance of Al and inevitable impurities, with a content of a single impurity of ≤ 0.05 wt.%, and a total impurity content of ≤ 0.15 wt.%, based on a total mass of 100 wt.% of the cast aluminum alloy.

[0086] A method for preparing the cast aluminum alloy was the same as that in Example 8.Example 11

[0087] A cast aluminum alloy included 1.5 wt.% of Fe, 1 wt.% of Ni, 0.6 wt.% of Cu, and a balance of Al and inevitable impurities, with a content of a single impurity of ≤ 0.05 wt.%, and a total impurity content of ≤ 0.15 wt.%, based on a total mass of 100 wt.% of the cast aluminum alloy.

[0088] Difference between a method for preparing the cast aluminum alloy in Example 11 and the preparation method in Example 8 was that a T6 heat treatment was further performed during the preparation of cast aluminum alloy. The cast aluminum alloy obtained was subjected to a solution treatment at 520°C for 4 h, taken out for water quenching, subjected to an aging treatment at 180°C for 3 h, and after completion, taken out for air cooling, with an interval between the solution treatment and the aging treatment not exceeding 0.5 h.Example 12

[0089] The alloy composition and preparation method were the same as those in Example 9, with the only difference being that the aluminum alloy melt was cast into a casting mold preheated to 150°C, and other conditions were the same.Example 13

[0090] A cast aluminum alloy included 2 wt.% of Fe, 1.5 wt.% of Ni, 0.6 wt.% of Cu, and a balance of Al and inevitable impurities, with a content of a single impurity of ≤ 0.05 wt.%, and a total impurity content of ≤ 0.15 wt.%, based on a total mass of 100 wt.% of the cast aluminum alloy.

[0091] A method for preparing the cast aluminum alloy was the same as that in Example 8.Example 14

[0092] A cast aluminum alloy included 1.7 wt.% of Fe, 0.5 wt.% of Ni, 0.3 wt.% of Cu, and a balance of Al and inevitable impurities, with a content of a single impurity of ≤ 0.05 wt.%, and a total impurity content of ≤ 0.15 wt.%, based on a total mass of 100 wt.% of the cast aluminum alloy.

[0093] A method for preparing the cast aluminum alloy was the same as that in Example 8.Comparative Example 1

[0094] A cast aluminum alloy for a motor rotor included 1 wt.% of Fe, 1 wt.% of Ni, 0 wt.% of Mg, and a balance of Al and inevitable impurities, with a content of a single impurity of ≤ 0.05 wt.%, and a total impurity content of ≤ 0.15 wt.%, based on a total mass of 100 wt.% of the cast aluminum alloy.

[0095] A method for preparing the cast aluminum alloy was the same as that in Example 1.Comparative Example 2

[0096] A cast aluminum alloy for a motor rotor included 0.3 wt.% of Fe, 4.5 wt.% of Ni, 0 wt.% of Mg, 0 wt.% of Si, and a balance of Al and inevitable impurities, with a content of a single impurity of ≤ 0.05 wt.%, and a total impurity content of ≤ 0.15 wt.%, based on a total mass of 100 wt.% of the cast aluminum alloy.

[0097] A method for preparing the cast aluminum alloy was the same as that in Example 1.Comparative Example 3

[0098] A cast aluminum alloy included 1.5 wt.% of Fe, 1 wt.% of Ni, 0 wt.% of Cu, and a balance of Al and inevitable impurities, with a content of a single impurity of ≤ 0.05 wt.%, and a total impurity content of ≤ 0.15 wt.%, based on a total mass of 100 wt.% of the cast aluminum alloy.

[0099] A method for preparing the cast aluminum alloy was the same as that in Example 8.Comparative Example 4

[0100] A cast aluminum alloy included 1.5 wt.% of Fe, 1 wt.% of Ni, 0.9 wt.% of Cu, and a balance of Al and inevitable impurities, with a content of a single impurity of ≤ 0.05 wt.%, and a total impurity content of ≤ 0.15 wt.%, based on a total mass of 100 wt.% of the cast aluminum alloy.

[0101] A method for preparing the cast aluminum alloy was the same as that in Example 8.Comparative Example 5

[0102] A cast aluminum alloy included 1.5 wt.% of Fe, 1 wt.% of Ni, 0.3 wt.% of Cu, 0.3 wt.% of Mg, 0.2 wt.% of Si, and a balance of Al and inevitable impurities, with a content of a single impurity of ≤ 0.05 wt.%, and a total impurity content of ≤ 0.15 wt.%, based on a total mass of 100 wt.% of the cast aluminum alloy.

[0103] A method for preparing the cast aluminum alloy was the same as that in Example 8, with the only difference being that, during the step of smelting of the aluminum alloy melt, pure iron, pure nickel, pure copper, pure magnesium and an aluminum-silicon master alloy were added, and were completely submerged into aluminum liquid.

[0104] The method for preparing the cast aluminum alloy was the same as that in Example 8.

[0105] Compositions and preparation methods of cast aluminum alloys of Examples 1 to 7 and Comparative Examples 1 to 2 are shown in Table 1, and corresponding performance test data are shown in Table 2. IACS test was conducted using an eddy current conductivity meter, model PZ-60A. Porosity was determined by statistically calculating an area of voids per unit area in metallographic images. Yield strength, tensile strength and elongation were obtained in accordance with the GB / T228.1-2010 testing standard. Table 1. Compositions and preparation methods of cast aluminum alloys of Examples 1 to 7 and Comparative Examples 1 to 2Experiment No.Preparation MethodComposition (wt %)(Fe,Ni) 4 Al 13 Phase Content (mol %)NiAl 3 Phase Content (mol %)AlFeNiMgExample 1Casting (Mold at Room Temperature)balance1.510.35.8 / Example 2Casting (performing T6 Heat Treatment)balance1.510.35.8 / Example 3Casting (Mold at Room Temperature)balance110.34.0 / Example 4Casting (performing T6 Heat Treatment)balance110.34.0 / Example 5Casting (Mold Preheated to 150°C)balance110.34.0 / Example 6Casting (Mold at Room Temperature)balance210.35.8 / Example 7Casting (Mold at Room Temperature)balance1.60.80.154.6 / Comparative Example 1Casting (Mold at Room Temperature)balance1104.0 / Comparative Example 2Casting (Mold at Room Temperature)balance0.34.50 / 8.7 Table 2. Performance Test Results of Cast Aluminum Alloys of Examples 1 to 7 and Comparative Examples 1 to 2 Experiment No.Electrical Conductivity (% IACS)Yield Strength (MPa)Tensile Strength (MPa)Elongation (%)Porosity (%)Example 152.5±0.475158160.19Example 252.2±0.372153180.19Example 353.0±0.370160200.28Example 452.7±0.265152220.29Example 550.0±0.368155190.27Example 650.7+0.280163140.25Example 750.4+0.370164180.20Comparative Example 153.4+0.365135210.19Comparative Example 249.4±0.180165100.41

[0106] It can be seen from Tables 1 and 2 that the cast aluminum alloys of Examples 1 to 7 exhibit good overall performance, demonstrating a good yield strength of 65 MPa or above and a tensile strength of 150 MPa or above while maintaining an excellent electrical conductivity of 50.0 % IACS or above. Moreover, compared with the cast aluminum alloy with high nickel content of Comparative Example 2, the cast aluminum alloys in Examples 1 to 7 of the present disclosure have a relatively low nickel content, leading to a significant reduction in production costs.

[0107] By comparing Example 1, Example 3 and Example 6, it can be observed that when a Fe content is reduced, a (Fe,Ni) 4 Al 13 phase content in the cast aluminum alloy decreases, and the electrical conductivity and the elongation increase. By comparing Example 2 with Example 4, the same trend can also be observed.

[0108] By comparing Example 1 with Example 2, it can be seen that when no T6 heat treatment is performed, the yield strength and the tensile strength of the cast aluminum alloy are significantly increased. By comparing Example 3 with Example 4, the same trend can also be observed. However, after performing the T6 heat treatment, it is not conducive to improving the strength, and thus it is preferable that no heat treatment is performed in the present disclosure.

[0109] By comparing Example 3 with Example 5, it can be observed that maintaining the mold at room temperature during casting yields better results than preheating the mold in advance. Compared with a manner of preheating the mold in advance in Example 5, casting the aluminum alloy melt into the mold being not preheated in Example 3 increases a temperature gradient between the aluminum alloy melt and the mold, increasing a cooling rate and improving the yield strength, the tensile strength and the elongation of the cast aluminum alloy.

[0110] By comparing Example 3 with Comparative Example 1, it can be observed that when the cast aluminum alloy includes no Mg, the yield strength and the tensile strength of the cast aluminum alloy are significantly reduced.

[0111] Compositions and preparation methods of the cast aluminum alloys of Examples 8 to 14 and Comparative Examples 3 to 5 are shown in Table 3, and corresponding performance test data are shown in Table 4. IACS test was conducted using an eddy current conductivity meter, model PZ-60A. Porosity was determined by statistically calculating an area of voids per unit area in metallographic images. Yield strength, tensile strength and elongation were obtained in accordance with the GB / T228.1-2010 testing standard. Table 3. Compositions and Preparation Methods of Cast Aluminum Alloys of Examples 8 to 14 and Comparative Examples 3 to 5Experiment No.Preparation MethodElement Content (wt %)AlFeNiCuMgSiExample 8Casting (mold being not preheated)balance110.600Example 9Casting (mold being not preheated)balance1.510.600Example 10Casting (mold being not preheated)balance210.600Example 11Casting (performing T6 Heat Treatment)balance1.510.600Example 12Casting (Mold Preheated to 150°C)balance1.510.600Example 13Casting (mold being not preheated)balance21.50.600Example 14Casting (mold being not preheated)balance1.70.50.300Comparative Example 3Casting (mold being not preheated)balance1.51000Comparative Example 4Casting (mold being not preheated)balance1.510.900Comparative Example 5Casting (mold being not preheated)balance1.510.30.30.2 Table 4. Performance Test Results of Cast Aluminum Alloys of Examples 8 to 14 and Comparative Examples 3 to 5 Experiment No.Electrical Conductivity (% IACS)Tensile Strength (MPa)Yield Strength (MPa)Elongation (%)Porosity (%)Example 850.8+0.218888200.08Example 949.3±0.118190160.02Example 1047.6±0.118592160.04Example 1149.2±0.318085150.02Example 1249.0±0.316576150.04Example 1347.3±0.219095130.06Example 1450.1±0.316077180.04Comparative Example 350.9±0.314570200.19Comparative Example 445.8±0.319593170.06Comparative Example 543.6±0.516570170.02

[0112] It can be seen from Tables 3 and 4 that the cast aluminum alloys of Examples 8 to 14 exhibit good overall performance, demonstrating an excellent yield strength of 76 MPa or above and a tensile strength of 160 MPa or above while maintaining a good electrical conductivity of 47% IACS or above. Moreover, compared with the cast aluminum alloy with high nickel content in the related art, the cast aluminum alloys in Examples 8 to 14 of the present disclosure have a relatively low nickel content, resulting in relatively low production costs.

[0113] By comparing Examples 8 to 10, it can be observed that when a Fe content is reduced, the electrical conductivity and the elongation of the cast aluminum alloy are improved.

[0114] By comparing Example 9 with Example 11, it can be observed that after the cast aluminum alloy of Example 11 is subjected to the T6 heat treatment, the cast aluminum alloy exhibits a slight decrease in electrical conductivity, a decrease in elongation, and a decline in both yield strength and tensile strength. Overall, the cast aluminum alloy that is not subjected to the T6 heat treatment has better comprehensive performance.

[0115] By comparing Example 9 with Example 12, it can be seen that maintaining the mold at room temperature during casting yields better results than preheating the mold in advance. Compared with a manner of preheating the mold in advance in Example 12, casting the aluminum alloy melt into the mold being not preheated in Example 9 increases a temperature gradient between the aluminum alloy melt and the mold, increasing a cooling rate, and improving the electrical conductivity, the yield strength, the tensile strength and the elongation of the cast aluminum alloy.

[0116] By comparing Example 9 with Comparative Examples 3 to 4, it can be seen that when a Cu content of Comparative Example 3 is lower than a content range defined in the examples of the present disclosure, the yield strength and the tensile strength of the cast aluminum alloy are significantly decreased. When a Cu content of Comparative Example 4 is higher than a content range defined in the examples of the present disclosure, although the yield strength and the tensile strength of the cast aluminum alloy are excellent, its electrical conductivity is greatly reduced.

[0117] By comparing Example 9 with Comparative Example 5, it can be seen that the addition of Mg and Si, along with the reduction of Cu content in Comparative Example 5, leads to a significant decrease in the yield strength, the tensile strength and the electrical conductivity of the cast aluminum alloy. Therefore, the cast aluminum alloys of the examples in the present disclosure does not include Mg and Si.

[0118] Reference throughout the present disclosure to "an embodiment," "some embodiments," "an example," "a specific example," or "some examples," means that a particular feature, structure, material, or characteristic described in connection with the embodiment or example is included in at least one embodiment or example of the present disclosure. The schematic expressions of the above-mentioned terms throughout this specification are not necessarily referring to the same embodiment or example. Moreover, the particular features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples. In addition, those skilled in the art can combine the different embodiments or examples and features of different embodiments or examples described in this specification without being mutually inconsistent.

[0119] Although the embodiments of the present disclosure have been shown and described above, it is to be understood that the above embodiments are illustrative and cannot be construed as limiting the present disclosure, and those skilled in the art may make changes, modifications, substitutions, and variations to the above embodiments within the scope of the present disclosure.

Claims

1. A cast aluminum alloy for a motor rotor, comprising: 0.5 to 2 wt.% of Fe, 0.1 to 1 wt.% of Ni, 0.1 to 0.5 wt.% of Mg, and a balance of Al and inevitable impurities, based on a total mass of 100 wt.% of the cast aluminum alloy.

2. The cast aluminum alloy for the motor rotor according to claim 1, comprising: 0.5 to 1.5 wt.% of Fe, 0.5 to 1 wt.% of Ni, 0.1 to 0.35 wt.% of Mg, and a balance of Al and inevitable impurities, with a content of a single impurity of ≤ 0.05 wt.%, and a total impurity content of ≤ 0.15 wt.%, based on a total mass of 100 wt.% of the cast aluminum alloy.

3. The cast aluminum alloy for the motor rotor according to claim 1, wherein a total content of Fe and Ni is in a range of 2 to 2.5 wt.%.

4. The cast aluminum alloy for the motor rotor according to claim 1, wherein a mole fraction of a (Fe,Ni)4Al13 phase in the cast aluminum alloy is in a range of 4 to 6 mol%.

5. The cast aluminum alloy for the motor rotor according to any one of claims 1 to 4, wherein the cast aluminum alloy has a room temperature electrical conductivity of 50% IACS or more.

6. The cast aluminum alloy for the motor rotor according to any one of claims 1 to 4, wherein the cast aluminum alloy has a yield strength of 65 MPa or more; and / or a tensile strength of 150 MPa or more.

7. The cast aluminum alloy for the motor rotor according to any one of claims 1 to 4, wherein the cast aluminum alloy has a porosity of 0.3% or less; and / or an elongation of 14% or more.

8. A cast aluminum alloy for a motor rotor, comprising: 0.5 to 2 wt.% of Fe, 0.3 to 1.5 wt.% of Ni, 0.1 to 0.8 wt.% of Cu, and a balance of Al and inevitable impurities, based on a total mass of 100 wt.% of the cast aluminum alloy.

9. The cast aluminum alloy according to claim 8, comprising: 1 to 1.5 wt.% of Fe, 0.3 to 1 wt.% of Ni, 0.1 to 0.6 wt.% of Cu, and a balance of Al and inevitable impurities, with a content of a single impurity of ≤ 0.05 wt.%, and a total impurity content of ≤ 0.15 wt.%, based on a total mass of 100 wt.% of the cast aluminum alloy.

10. The cast aluminum alloy according to claim 8, wherein a total content of Fe and Ni is in a range of 0.8 to 3 wt.%.

11. The cast aluminum alloy according to claim 10, wherein the total content of Fe and Ni is in a range of 2 to 2.5 wt.%.

12. The cast aluminum alloy according to any one of claims 8 to 11, wherein the cast aluminum alloy has a room temperature electrical conductivity of 47% IACS or more.

13. The cast aluminum alloy according to any one of claims 8 to 11, wherein the cast aluminum alloy has a porosity of 0.1% or less.

14. The cast aluminum alloy according to any one of claims 8 to 11, wherein the cast aluminum alloy has an elongation of 13% or more.

15. A method for preparing a cast aluminum alloy for a motor rotor according to any one of claims 1 to 14, comprising: adding raw materials of the aluminum alloy in proportion, and smelting the raw materials of the aluminum alloy to obtain an aluminum alloy melt; and refining and degassing the aluminum alloy melt, followed by casting the aluminum alloy melt into a casting mold to obtain the cast aluminum alloy.

16. The method for preparing the cast aluminum alloy for the motor rotor according to claim 15, wherein the casting mold is not preheated and maintained at room temperature.

17. The method for preparing the cast aluminum alloy for the motor rotor according to claim 15 or 16, wherein no heat treatment is performed after the cast aluminum alloy is obtained.

18. The method for preparing the cast aluminum alloy for the motor rotor according to claim 15 or 16, comprising: preheating a pit furnace in an empty state at a preheating temperature of 400 °C or above to remove moisture from the pit furnace, and preheating pure aluminum; placing preheated pure aluminum into the pit furnace for smelting at a smelting temperature of 780 to 800 °C; skimming off surface slag and oxide scale after the pure aluminum is completely melted, and maintaining a melt temperature; adding pure iron, pure nickel and pure magnesium, or adding an aluminum-iron master alloy, an aluminum-nickel master alloy and an aluminum-magnesium master alloy, or adding pure iron, pure nickel and pure copper, completely submerging the raw materials of the aluminum alloy into aluminum liquid, and completely melting the raw materials of the aluminum alloy, following by standing for 2 to 3 h to obtain the aluminum alloy melt; wrapping a refining agent with aluminum foil and drying the refining agent, and preheating a stainless steel bell; pressing the refining agent preheated to a bottom of the aluminum alloy melt with the stainless steel bell preheated; introducing high-purity argon gas into the aluminum alloy melt, and refining and degassing the aluminum alloy melt; casting the aluminum alloy melt into the casting mold while maintaining a casting temperature of 700 to 740 °C; and opening the casting mold to obtain the cast aluminum alloy after an aluminum-iron-nickel alloy melt solidifies and cools.

19. A motor rotor, prepared from the cast aluminum alloy according to any one of claims 1 to 14.

20. A vehicle, comprising the motor rotor according to claim 19.

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