Aluminum alloy and preparation method and application thereof

Abstract

The present invention provides an aluminum alloy, a preparation method, and an application thereof, belonging to the technical field of aluminum alloys. Based on the total mass of the aluminum alloy being 100 wt.%, the aluminum alloy comprises the following components: Fe 0.8-1.2 wt.%, Ni 0.8-1.2 wt.%, Mg 0.2-0.45 wt.%, Si 0.3-0.5 wt.%, with the remainder being Al and unavoidable impurities. The aluminum alloy has both high electrical conductivity and high strength, particularly significantly improving the yield strength and tensile strength of the aluminum alloy. Furthermore, the aluminum alloy exhibits long-term medium-temperature strength stability, and its strength does not decrease after prolonged heat preservation.

Description

Technical Field

[0001] The present invention belongs to the technical field of aluminum alloys, and in particular relates to an aluminum alloy and a preparation method and application thereof. Background Art

[0002] Pure aluminum boasts an electrical conductivity of up to 62% IACS and a density only 30% of pure copper, making it a promising metal material for applications in vehicles, aerospace, power transmission equipment, and other fields. However, pure aluminum lacks sufficient strength for practical applications. Therefore, alloying elements such as Mg, Si, Cu, Ni, and Fe are often added to pure aluminum to form aluminum alloys to enhance their strength.

[0003] However, the mechanical properties of aluminum-silicon-magnesium alloys (Al-Si-Mg) and aluminum-copper alloys (Al-Cu) rapidly decline after service at medium temperatures of 100-200°C, which is one of the bottlenecks limiting the application of high-strength and high-conductivity aluminum alloys. The reason for this problem is that the main precipitate phase used to improve the strength of Al-Si-Mg alloys is Mg2Si, and the main precipitate phase used to improve the strength of Al-Cu alloys is Al2Cu. However, these precipitates grow significantly after long-term holding in the temperature range of 100-200°C, resulting in a decrease in the mechanical properties of the aluminum alloys.

[0004] Related patent US2021 / 0332461 discloses an Al-4.3~6%Ni-0.2~0.8%Fe alloy, which uses the Al-Ni-Fe metal compound formed during the solidification process to improve the strength. At the same time, due to the low solid solubility of Ni and Fe in aluminum, the alloy has high electrical conductivity (50%IACS) and high strength (yield strength 90MPa, tensile strength 150MPa). However, there are two problems with this alloy. First, it only relies on the larger second phase formed during the solidification process for strengthening, and its strength is much lower than that of Al-Si-Mg alloys and Al-Cu alloys strengthened by precipitated phases such as Mg2Si and Al2Cu. Second, adding a high content of Ni will significantly increase the cost of raw materials.

[0005] Therefore, there is an urgent need to develop an aluminum alloy that has both high strength and high conductivity and can maintain high strength after serving at 100-200°C. Summary of the Invention

[0006] The present invention aims to solve one of the technical problems in the related art to at least a certain extent. To this end, embodiments of the present invention provide an aluminum alloy and a preparation method and application thereof.

[0007] The aluminum alloy of the embodiment of the present invention includes the following components, based on the total mass of the aluminum alloy being 100 wt.%, Fe 0.8-1.2 wt.%, Ni 0.8-1.2 wt.%, Mg 0.2-0.45 wt.%, Si 0.3-0.5 wt.%, and the balance being Al and unavoidable impurities.

[0008] The advantages and technical effects brought by the aluminum alloy of the embodiment of the present invention are as follows:

[0009] (1) The main phases of the aluminum alloy of the embodiment of the present invention are Al9FeNi phase and α-Al phase; during the solidification process of the aluminum alloy melt, Al9FeNi compound is formed, existing as the second phase and the final eutectic form, and is discontinuously distributed between the α-Al dendrites, which can improve the strength of the aluminum alloy; in the cast state, Mg element and a small amount of Si element are mainly dissolved in α-Al, playing a solid solution strengthening role, and also improving the strength of the aluminum alloy;

[0010] (2) The aluminum alloy of the embodiment of the present invention improves the medium-temperature stability of the precipitated phase by combining the specified content of Fe-Ni-Mg-Si. Therefore, the aluminum alloy of the embodiment of the present invention has long-term medium-temperature strength stability, and the strength will not be significantly reduced after long-term heat preservation.

[0011] (3) Optionally, after heat treatment, the cast aluminum alloy will precipitate a Mg2Si strengthening phase, which can further improve the yield strength and tensile strength of the aluminum alloy.

[0012] (4) Compared with the Al-4.3-6% Ni-0.2-0.8% Fe alloy in the related art, the aluminum alloy in the embodiment of the present invention uses less nickel and iron content, which reduces the cost of raw materials.

[0013] In some embodiments, the mass percentage of Fe is 0.9-1.1 wt.%.

[0014] In some embodiments, the mass percentage of Ni is 0.9-1.1 wt.%.

[0015] In some embodiments, the mass percentage of Mg is 0.3-0.45 wt.%.

[0016] In some embodiments, the mass percentage of Si is 0.4-0.5 wt.%.

[0017] In some embodiments, the ratio between the mass percentage of Mg and the mass percentage of Si is (0.7-2):1.

[0018] An embodiment of the present invention also provides a method for preparing an aluminum alloy, comprising the following steps: adding the raw materials of the aluminum alloy in proportion, smelting, and obtaining an aluminum alloy melt; refining and degassing the aluminum alloy melt, and then casting it into a casting mold; after the aluminum alloy melt solidifies and cools, opening the mold and taking out the cast aluminum alloy.

[0019] The advantages and technical effects brought by the method for preparing the aluminum alloy according to the embodiment of the present invention are as follows:

[0020] (1) The preparation method of the embodiment of the present invention has simple steps and is suitable for industrial promotion;

[0021] (2) The aluminum alloy prepared by the preparation method of the embodiment of the present invention has both high strength and high electrical conductivity, and can still maintain high strength after service at 100-200°C;

[0022] (3) The raw materials of the aluminum alloy used in the preparation method of the embodiment of the present invention are relatively low in cost and have great market competitiveness.

[0023] In some embodiments, the preparation method further includes: heat treating the cast aluminum alloy.

[0024] In some embodiments, the heat treatment includes: annealing the cast aluminum alloy at 240-260°C for 2-6 hours, and taking it out after cooling; or, first solutionizing the cast aluminum alloy at 500-540°C for 3-5 hours, taking it out after cooling, and then keeping it at 160-200°C for 12-100 hours.

[0025] In some embodiments, the casting mold is not preheated and maintained at room temperature.

[0026] In some embodiments, the aluminum alloy according to the embodiments of the present invention or the aluminum alloy obtained by the preparation method according to the embodiments of the present invention can be used in vehicles. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] Figure 1 is the calculated atomic content ratio of Mg and Si in FCC-Al corresponding to different Mg and Si mass fractions in the alloy at a solution temperature of 520°C;

[0028] Figure 2 Graphs of electrical conductivity and microhardness of Example 1-1, Example 1-2, Example 1-3, and Comparative Example 1-1 and Comparative Example 2-1;

[0029] Figure 3 are scanning electron microscope photos of Example 1-1 and Comparative Example 2-1;

[0030] Figure 4 is a graph showing the change in hardness and thermal conductivity of Example 1-2 with medium temperature service time;

[0031] Figure 5 is a graph showing the change in hardness and thermal conductivity of Examples 1-3 with medium temperature service time;

[0032] Figure 6 These are the tensile mechanical property curves of Example 1-1, Example 1-2, Example 1-3 and Comparative Example 1-1, Comparative Example 2-1. DETAILED DESCRIPTION

[0033] The embodiments of the present invention are described in detail below, and examples of the embodiments are shown in the accompanying drawings. The embodiments described below with reference to the accompanying drawings are exemplary and intended to be used to explain the present invention, but should not be understood as limiting the present invention.

[0034] An embodiment of the present invention provides an aluminum alloy, which, based on 100% by total mass of the aluminum alloy, includes the following components: Fe 0.8-1.2wt.%, Ni 0.8-1.2wt.%, Mg 0.3-0.45wt.%, Si 0.3-0.5wt.%, and the balance being Al and unavoidable impurities.

[0035] The main phases of the aluminum alloy are Al9FeNi phase and α-Al phase; during the solidification process of the aluminum alloy melt, Al9FeNi compound is formed, which exists in the form of second phase and final eutectic, and is discontinuously distributed between α-Al dendrites, which can improve the strength of the aluminum alloy; in the cast state, Mg element and a small amount of Si element are mainly dissolved in α-Al, which plays a role of solid solution strengthening and also improves the strength of the aluminum alloy; therefore, the aluminum alloy can maintain excellent electrical conductivity while having high strength. Moreover, the combination of Fe-Ni-Mg-Si improves the medium-temperature stability of the precipitated phase, and greatly improves the strength stability of the aluminum alloy after long-term heat preservation. Optionally, after heat treatment, the cast aluminum alloy will also precipitate Mg2Si strengthening phase, further improving the strength of the aluminum alloy. In addition, compared with the high-Ni content aluminum alloy in the related art, the Ni content in the aluminum alloy of the embodiment of the present invention is relatively low, so the raw material cost of the aluminum alloy is also relatively low.

[0036] In some embodiments, the molar percentage of the Al9FeNi phase in the aluminum alloy is 3-5 mol%. The Al9FeNi phase is a primary phase and forms a eutectic at the end of solidification. This eutectic formation occurs at the end of solidification, through the melt → α-Al + Al9FeNi phase. The eutectic Al9FeNi phase has fine and uniform particles, which helps reduce the impact on elongation. When the Al9FeNi content in the aluminum alloy is too low, it is not conducive to improving the yield strength and tensile strength of the aluminum alloy. When the Al9FeNi content in the aluminum alloy is too high, it is not conducive to improving the electrical conductivity of the aluminum alloy.

[0037] Based on the total weight of the aluminum alloy as 100 wt.%, in the aluminum alloys of the embodiments of the present invention, the weight percentage of Fe is 0.8-1.2 wt.%, such as 0.8 wt.%, 0.9 wt.%, 1.0 wt.%, 1 wt.%, 1.1 wt.%, and 1.2 wt.%, and the weight percentage of Ni is 0.8-1.2 wt.%, such as 0.8 wt.%, 0.9 wt.%, 1.0 wt.%, 1.1 wt.%, and 1.2 wt.%. When the weight percentage of Fe is less than 0.8 wt.% and the weight percentage of Ni is less than 0.8 wt.%, sufficient Al9FeNi phase is difficult to form, resulting in low yield strength and tensile strength of the aluminum alloy. When the weight percentage of Fe is greater than 1.2 wt.% and the weight percentage of Ni is greater than 1.2 wt.%, the Al9FeNi phase becomes excessive, reducing the electrical conductivity of the aluminum alloy. Furthermore, when the weight percentage of Ni is greater than 1.2 wt.%, the higher cost of Ni leads to a corresponding increase in the raw material cost of the aluminum alloy. Preferably, the mass percentage of Fe is 0.9-1.1 wt.%, and the mass percentage of Ni is 0.9-1.1 wt.%.

[0038] Taking the total mass of the aluminum alloy as 100wt.%, in the aluminum alloy of the embodiment of the present invention, the mass percentage of Mg is 0.2-0.45wt.%, for example, 0.2wt.%, 0.25wt.%, 0.3wt.%, 0.35wt.%, 0.4wt.%, 0.45wt.%, etc. When the mass percentage of Mg is lower than 0.2wt.%, it does not have a solid solution strengthening effect, thereby greatly reducing the yield strength and tensile strength of the aluminum alloy. When the mass percentage of Mg is higher than 0.45wt.%, the electrical conductivity of the aluminum alloy is reduced, and the plasticity of the aluminum alloy is also reduced, resulting in easy cracking. Preferably, the mass percentage of Mg is 0.3-0.45wt.%.

[0039] Taking the total mass of the aluminum alloy as 100wt.%, in the aluminum alloy of the embodiment of the present invention, the mass percentage of Si is 0.3-0.5wt.%, for example, 0.3wt.%, 0.35wt.%, 0.4wt.%, 0.45wt.%, 0.5wt.%, etc. When the mass percentage of Si is lower than 0.3wt.%, it does not have a solid solution strengthening effect, thereby greatly reducing the yield strength and tensile strength of the aluminum alloy. When the mass percentage of Si is higher than 0.5wt.%, the electrical conductivity of the aluminum alloy is reduced, and the elongation of the aluminum alloy is also reduced, causing the cast aluminum alloy to become brittle. Preferably, the mass percentage of Si is 0.4-0.5wt.%.

[0040] In some embodiments, the ratio of the mass percentage of Mg to the mass percentage of Si is (0.7-2):1, for example, 0.7:1, 0.8:1, 0.9:1, 1.0:1, 1.1:1, 1.2:1, 1.3:1, 1.4:1, 1.5:1, 1.6:1, 1.7:1, 1.8:1, 1.9:1, 2.0:1, etc. During the heat treatment process, a certain amount of dissolved Mg and Si precipitates to form a Mg2Si precipitate phase, which improves the strength and conductivity. However, the ratio of Mg to Si needs to be controlled. Figure 1 It is the change in the atomic ratio of Mg and Si dissolved in Fcc under different mass ratios of Mg and Si in the alloy. It can be seen that the atomic ratio of Mg and Si can be guaranteed to be greater than or equal to 2:1 in the design area to ensure the formation of Mg2Si. Therefore, the aluminum alloy can have both high electrical conductivity and high strength, especially greatly improving the yield strength and tensile strength of the aluminum alloy. When the ratio between the mass percentage of Mg and the mass percentage of Si is too low, the efficiency of the Mg2Si precipitation phase will be reduced during heat treatment. When the ratio between the mass percentage of Mg and the mass percentage of Si is too high, the excessive solid-solution Mg will reduce the thermal conductivity of the alloy and increase the hot cracking of the aluminum alloy. After the aluminum alloy has been in service at 100-200°C, it is not conducive to the aluminum alloy to maintain high strength.

[0041] In some embodiments, the content of a single impurity is ≤0.05 wt.%, and the total impurity content is ≤0.15 wt.%. The impurity content meets the requirements of standard GB / T 8733-2016.

[0042] In addition, an embodiment of the present invention also provides a method for preparing an aluminum alloy, comprising the following steps: adding the raw materials of the aluminum alloy in proportion, smelting, and obtaining an aluminum alloy melt; refining and degassing the aluminum alloy melt, and then casting it into a casting mold; after the aluminum alloy melt solidifies and cools, opening the mold and taking out the cast aluminum alloy.

[0043] The preparation method of the embodiment of the present invention has simple steps and is suitable for industrial promotion. The prepared aluminum alloy has both high strength and high conductivity, and can still maintain high strength after service at 100-200°C. In addition, the raw material cost of the aluminum alloy is also low.

[0044] In some embodiments, the preparation method of the aluminum alloy specifically includes the following steps: preheating a pit furnace in an empty state to remove moisture in the furnace, the preheating temperature being above 400°C, and simultaneously preheating pure aluminum, then placing the preheated pure aluminum into the pit furnace for smelting, the smelting temperature being 780-800°C, after the pure aluminum is completely melted, removing the surface slag and removing the oxide scale, maintaining the melt temperature, adding pure iron, pure nickel, pure magnesium and aluminum-silicon master alloy, and completely immersing the aluminum liquid, and after the alloying elements are completely melted, standing for 2-3 hours to obtain the aluminum alloy melt;

[0045] The refining agent is wrapped with aluminum foil and dried, and a stainless steel bell jar is preheated at the same time. The preheated stainless steel bell jar is then used to press the preheated refining agent to the bottom of the aluminum alloy melt, and an inert gas is introduced into the aluminum alloy melt to carry out the refining and degassing process of the aluminum alloy melt, while maintaining the casting temperature at 730-750°C; the aluminum alloy melt is poured into the casting mold within 30 seconds, and after the aluminum alloy melt solidifies and cools, the mold is opened and the cast aluminum alloy is taken out.

[0046] In some embodiments, the casting mold is not preheated and maintained at room temperature. Compared to preheating the casting mold, not preheating the casting mold increases the temperature gradient between the aluminum alloy melt and the casting mold, thereby increasing the cooling rate, which is beneficial for improving the electrical conductivity, yield strength, and tensile strength of the aluminum alloy.

[0047] In some embodiments, the preparation method of the present invention further comprises: heat treating the cast aluminum alloy. After the heat treatment, the cast aluminum alloy will precipitate a Mg2Si strengthening phase, which can further improve the strength of the aluminum alloy.

[0048] In some embodiments, the heat treatment specifically includes T5 heat treatment: annealing the cast aluminum alloy at 240-260°C for 2-6 hours, taking it out after cooling; or, including T6 heat treatment: first solutionizing the cast aluminum alloy at 500-540°C for 3-5 hours, taking it out after cooling, and then keeping it at 160-200°C for 12-100 hours.

[0049] In addition, the aluminum alloy of the embodiment of the present invention or the aluminum alloy obtained by the preparation method of the embodiment of the present invention can be used for vehicle motor rotors, battery pack bottom guard plates, vehicle front floors, middle floors, rear floors and other parts.

[0050] The present invention will be described in detail below with reference to the embodiments and accompanying drawings.

[0051] Example 1

[0052] Example 1-1

[0053] An aluminum alloy comprises the following components, based on 100 wt.% of the total mass of the aluminum alloy: 1.0 wt.% Fe, 1.0 wt.% Ni, 0.45 wt.% Mg, 0.5 wt.% Si, and the balance being Al and unavoidable impurities.

[0054] The method for preparing the above-mentioned aluminum alloy comprises the following steps:

[0055] Step 1. Melting of aluminum alloy melt: First, preheat the pit furnace empty to remove moisture in the furnace at a temperature of 400°C. Simultaneously, preheat the pure aluminum. Then, place the preheated pure aluminum into the pit furnace for melting at a temperature of 800°C. After the pure aluminum is completely melted, remove the surface slag and remove the oxide scale. Maintaining the melt temperature, add pure iron, pure nickel, pure magnesium, and Al-10Si master alloy and completely immerse them in the aluminum liquid. After the alloying elements are completely melted, let it stand for about 2 hours to obtain the aluminum alloy melt.

[0056] Step 2. Preparation of the as-cast aluminum alloy: First, wrap the refining agent in aluminum foil and dry it. Simultaneously, preheat a stainless steel bell jar. The preheated refining agent is then pressed to the bottom of the melt using the preheated stainless steel bell jar. High-purity argon gas is introduced into the aluminum alloy melt to complete the refining and degassing process, maintaining a casting temperature of 745°C. Next, the aluminum alloy melt is poured into a room-temperature casting mold. After the aluminum alloy melt solidifies and cools, the casting is removed from the mold to obtain the as-cast aluminum alloy. The casting mold is made of cast iron, and the casting time should be controlled within 30 seconds.

[0057] Example 1-2

[0058] An aluminum alloy and a preparation method thereof are the same as those in Example 1-1, except that after obtaining the cast aluminum alloy, step 3.T5 heat treatment is further performed: the cast aluminum alloy is heat treated at 250°C for 3 hours.

[0059] Examples 1-3

[0060] An aluminum alloy and a preparation method thereof are the same as those in Example 1-1, except that step 3.T6 heat treatment is performed after obtaining the cast aluminum alloy: the cast aluminum alloy is solutionized at 520°C for 4 hours, water-cooled, and then heat treated at 180°C for 12 hours.

[0061] Example 2

[0062] Example 2-1

[0063] An aluminum alloy and a preparation method thereof are the same as those in Example 1-1, except that the aluminum alloy comprises the following components: Fe 1.0 wt.%, Ni 1.0 wt.%, Mg 0.3 wt.%, Si 0.2 wt.%, and the balance being Al and unavoidable impurities.

[0064] Example 2-2

[0065] An aluminum alloy and a preparation method thereof are the same as those in Example 2-1, except that after obtaining the cast aluminum alloy, step 3.T5 heat treatment is further performed: the cast aluminum alloy is heat treated at 250°C for 3h.

[0066] Example 2-3

[0067] An aluminum alloy and its preparation method are the same as those in Example 2-1, except that step 3.T5 heat treatment is performed after obtaining the cast aluminum alloy: the cast aluminum alloy is solutionized at 520°C for 4 hours, water-cooled, and then heat treated at 180°C for 12 hours.

[0068] Example 3

[0069] Example 3-1

[0070] An aluminum alloy and a preparation method thereof are the same as those in Example 1-1, except that the aluminum alloy comprises the following components: Fe 1.0 wt.%, Ni 1.0 wt.%, Mg 0.3 wt.%, Si 0.3 wt.%, and the balance being Al and unavoidable impurities.

[0071] Example 3-2

[0072] An aluminum alloy and a preparation method thereof are the same as those in Example 3-1, except that after obtaining the cast aluminum alloy, step 3.T5 heat treatment is further performed: the cast aluminum alloy is heat treated at 250°C for 3 hours.

[0073] Example 3-3

[0074] An aluminum alloy and its preparation method are the same as those in Example 3-1, except that after obtaining the cast aluminum alloy, step 3.T6 heat treatment is also performed: the cast aluminum alloy is solutionized at 520°C for 4 hours, water-cooled, and then heat treated at 180°C for 12 hours.

[0075] Example 4

[0076] Example 4-1

[0077] An aluminum alloy and a preparation method thereof are the same as those in Example 1-1, except that the aluminum alloy comprises the following components: Fe 1.0 wt.%, Ni 1.0 wt.%, Mg 0.45 wt.%, Si 0.3 wt.%, and the balance being Al and unavoidable impurities.

[0078] Example 4-2

[0079] An aluminum alloy and a preparation method thereof are the same as those in Example 4-1, except that after obtaining the cast aluminum alloy, step 3.T5 heat treatment is further performed: the cast aluminum alloy is heat treated at 250°C for 3 hours.

[0080] Example 4-3

[0081] An aluminum alloy and its preparation method are the same as Example 4-1, except that after obtaining the cast aluminum alloy, step 3.T6 heat treatment is also performed: the cast aluminum alloy is solutionized at 520°C for 4 hours, water-cooled, and then heat treated at 180°C for 12 hours.

[0082] Comparative Example 1

[0083] Comparative Example 1-1

[0084] An aluminum alloy and a preparation method thereof are the same as those in Example 1-1, except that the aluminum alloy comprises the following components: 0.4 wt.% Fe, 3.4 wt.% Ni, and the balance being Al and unavoidable impurities.

[0085] Comparative Example 1-2

[0086] An aluminum alloy and a preparation method thereof are the same as those in comparative example 1-1, except that after obtaining the cast aluminum alloy, step 3.T5 heat treatment is further performed: the cast aluminum alloy is heat treated at 250°C for 3h.

[0087] Comparative Examples 1-3

[0088] An aluminum alloy and a preparation method thereof are the same as those of comparative example 1-1, except that step 3.T6 heat treatment is further performed after obtaining the cast aluminum alloy: the cast aluminum alloy is solutionized at 520°C for 4 hours, water-cooled, and then heat treated at 180°C for 12 hours.

[0089] Comparative Example 2

[0090] Comparative Example 2-1

[0091] An aluminum alloy and a preparation method thereof are the same as those in Example 1-1, except that the aluminum alloy comprises the following components: 2.0 wt.% Fe, 1.0 wt.% Ni, and the balance being Al and unavoidable impurities.

[0092] Comparative Example 2-2

[0093] An aluminum alloy and a preparation method thereof are the same as those in Comparative Example 2-1, except that after obtaining the cast aluminum alloy, step 3.T5 heat treatment is further performed: the cast aluminum alloy is heat treated at 250°C for 3h.

[0094] Comparative Examples 2-3

[0095] An aluminum alloy and its preparation method are the same as those in comparative example 2-1, except that step 3.T6 heat treatment is performed after obtaining the cast aluminum alloy: the cast aluminum alloy is solutionized at 520°C for 4 hours, water-cooled, and then heat treated at 180°C for 12 hours.

[0096] Comparative Example 3

[0097] Comparative Example 3-1

[0098] An aluminum alloy and a preparation method thereof are the same as those in Example 1-1, except that the aluminum alloy comprises the following components: 1.0 wt.% Fe, 1.0 wt.% Ni, and the balance being Al and unavoidable impurities.

[0099] Comparative Example 3-2

[0100] An aluminum alloy and a preparation method thereof are the same as those in Comparative Example 3-1, except that after obtaining the cast aluminum alloy, step 3.T5 heat treatment is further performed: the cast aluminum alloy is heat treated at 250°C for 3h.

[0101] Comparative Example 3-3

[0102] An aluminum alloy and its preparation method are the same as those in comparative example 3-1, except that step 3.T6 heat treatment is performed after obtaining the cast aluminum alloy: the cast aluminum alloy is solutionized at 520°C for 4 hours, water-cooled, and then heat treated at 180°C for 12 hours.

[0103] Comparative Example 4

[0104] Comparative Example 4-1

[0105] An aluminum alloy and a preparation method thereof are the same as those in Example 1-1, except that the aluminum alloy comprises the following components: Fe 2.0 wt.%, Ni 1.0 wt.%, Mg 0.3 wt.%, and the balance being Al and unavoidable impurities.

[0106] Comparative Example 4-2

[0107] An aluminum alloy and a preparation method thereof are the same as those in comparative example 4-1, except that after obtaining the cast aluminum alloy, step 3.T5 heat treatment is further performed: the cast aluminum alloy is heat treated at 250°C for 3h.

[0108] Comparative Example 4-3

[0109] An aluminum alloy and its preparation method are the same as those in comparative example 4-1, except that step 3.T6 heat treatment is performed after obtaining the cast aluminum alloy: the cast aluminum alloy is solutionized at 520°C for 4 hours, water-cooled, and then heat treated at 180°C for 12 hours.

[0110] Comparative Example 5

[0111] Comparative Example 5-1

[0112] An aluminum alloy and a preparation method thereof are the same as those in Example 1-1, except that the aluminum alloy comprises the following components: Fe 1.0 wt.%, Ni 1.0 wt.%, Mg 0.3 wt.%, and the balance being Al and unavoidable impurities.

[0113] Comparative Example 5-2

[0114] An aluminum alloy and a preparation method thereof are the same as those in Comparative Example 5-1, except that after obtaining the cast aluminum alloy, step 3.T5 heat treatment is further performed: the cast aluminum alloy is heat treated at 250°C for 3h.

[0115] Comparative Example 5-3

[0116] An aluminum alloy and its preparation method are the same as those in comparative example 5-1, except that step 3.T6 heat treatment is performed after obtaining the cast aluminum alloy: the cast aluminum alloy is solutionized at 520°C for 4 hours, water-cooled, and then heat treated at 180°C for 12 hours.

[0117] Comparative Example 6

[0118] Comparative Example 6-1

[0119] An aluminum alloy and a preparation method thereof are the same as those in Example 1-1, except that the aluminum alloy comprises the following components: Fe 1.0 wt.%, Ni 1.0 wt.%, Mg 0.6 wt.%, Si 0.6 wt.%, and the balance being Al and unavoidable impurities.

[0120] Comparative Example 6-2

[0121] An aluminum alloy and a preparation method thereof are the same as those in Comparative Example 6-1, except that after obtaining the cast aluminum alloy, step 3.T5 heat treatment is further performed: the cast aluminum alloy is heat treated at 250°C for 3 hours.

[0122] Comparative Example 6-3

[0123] An aluminum alloy and its preparation method are the same as those in comparative example 6-1, except that step 3.T6 heat treatment is performed after obtaining the cast aluminum alloy: the cast aluminum alloy is solutionized at 520°C for 4 hours, water-cooled, and then heat treated at 180°C for 12 hours.

[0124] Comparative Example 7

[0125] Comparative Example 7-1

[0126] An aluminum alloy and a preparation method thereof are the same as those in Example 1-1, except that the aluminum alloy comprises the following components: Fe 1.0 wt.%, Ni 1.0 wt.%, Mg 0.45 wt.%, Si 5 wt.%, and the balance being Al and unavoidable impurities.

[0127] Comparative Example 7-2

[0128] An aluminum alloy and a preparation method thereof are the same as those in Comparative Example 7-1, except that after obtaining the cast aluminum alloy, step 3.T5 heat treatment is further performed: the cast aluminum alloy is heat treated at 250°C for 3h.

[0129] Comparative Example 7-3

[0130] An aluminum alloy and its preparation method are the same as those in comparative example 7-1, except that step 3.T6 heat treatment is performed after obtaining the cast aluminum alloy: the cast aluminum alloy is solutionized at 520°C for 4 hours, water-cooled, and then heat treated at 180°C for 12 hours.

[0131] The composition of the aluminum alloys of Examples 1 to 4, the temperature difference between the liquid and solid phases ΔT s , phase, phase content, and phase composition are shown in Table 1 and Table 2. The composition, liquid-solid two-phase temperature difference ΔT of the aluminum alloys of Comparative Examples 1 to 7 are shown in Table 1 and Table 2. s , phase, phase content, and phase composition are shown in Table 3. Among them, the phase content and phase composition are calculated through the phase diagram. The room temperature conductivity, microhardness, yield strength, tensile strength and elongation of the aluminum alloys of Examples 1 to 4 and Comparative Examples 1 to 7 above are experimentally determined. The results of Examples 1 to 4 are shown in Tables 4 and 5, and the results of Comparative Examples 1 to 7 are shown in Tables 6 and 7. Among them, the room temperature conductivity test is carried out using an eddy current conductivity meter, and the instrument model is PZ-60A; the microhardness is obtained by testing with a Vickers microhardness tester; the yield strength, tensile strength and elongation are obtained in accordance with the GB / T228.1-2010 test standard. The stability of the medium-temperature mechanical properties of the aluminum alloys of Examples 1-2 and 1-3 above at 180°C for 100 hours is experimentally determined, and the results are as shown in the following table. Figure 4 and Figure 5The tensile mechanical properties of Example 1-1, Example 1-2, Example 1-3 and Comparative Example 1-1 and Comparative Example 2-1 were measured, and the results were as follows. Figure 6 shown.

[0132] Table 1. Composition and temperature difference ΔT of the aluminum alloys of Examples 1 and 2 s , phase, phase content, phase composition

[0133]

[0134] Table 2. Composition and Liquid-Solid Temperature Difference ΔT of Aluminum Alloys of Examples 3 to 4 s , phase, phase content, phase composition

[0135]

[0136] Table 3. Composition and liquid-solid temperature difference ΔT of the aluminum alloys of Comparative Examples 1 to 7 s , phase, phase content, phase composition

[0137]

[0138] Table 4. Performance test results of aluminum alloys of Examples 1 and 2

[0139]

[0140] Table 5. Performance test results of aluminum alloys of Examples 3 to 4

[0141]

[0142] Table 6. Performance test results of aluminum alloys of Comparative Examples 1 to 4

[0143]

[0144] Table 7. Performance test results of aluminum alloys of Comparative Examples 5 to 7

[0145]

[0146] Figure 1 is the calculated atomic content ratio of Mg and Si in FCC-Al corresponding to different Mg and Si mass fractions in the alloy at 520℃ solid solution temperature. Figure 1 The design composition area in is the composition window suitable for as-cast, aging and solution + aging treatments.

[0147] The data in the table demonstrates that the aluminum alloys of Examples 1 through 4, regardless of whether or not they have undergone heat treatment, exhibit both high electrical conductivity and high strength, and maintain high strength even after service at 100-200°C. A comparison of the unheat-treated Examples 1-1, 2-1, 3-1, and 4-1 with the heat-treated examples demonstrates that subsequent T5 or T6 heat treatment can further enhance the strength of the aluminum alloys, while also increasing their electrical conductivity.

[0148] From the comparison between Comparative Example 1 and Examples 1 to 4, it can be seen that Comparative Example 1 does not contain Mg and Si, and the Fe content is lower than the range of the embodiments of the present invention. At the same time, the Ni content is higher than the range of the embodiments of the present invention. The physical phases of the aluminum alloy are α-Al and Al3Ni, which leads to a significant decrease in the yield strength, tensile strength and elongation of the aluminum alloy.

[0149] From the comparison between Comparative Example 2 and Examples 1 to 4, it can be seen that Comparative Example 2 does not contain Mg and Si, and the Fe content is higher than the range of the embodiments of the present invention, without significantly changing the electrical conductivity of the aluminum alloy, while the elongation of the aluminum alloy is greatly improved, reaching 20.2%. However, the main problem of Comparative Example 2 is that the yield strength and tensile strength of the aluminum alloy are greatly reduced.

[0150] In the aluminum alloys of Examples 1 to 4, Mg and a small amount of Si are solid-solved in α-Al, which can play a solid-solution strengthening role. Therefore, the hardness of the aluminum alloys of Examples 1 to 4 is generally high.

[0151] Comparison of Comparative Example 3 with Examples 1 to 4 shows that Comparative Example 3 does not contain Mg and Si. The hardness of the aluminum alloy in Comparative Example 3 is significantly lower than that of Examples 1 to 4, indicating that the strength of Comparative Example 3 will also be significantly reduced. Therefore, it is necessary to introduce a certain amount of Mg and Si for solid solution and precipitation strengthening.

[0152] From the comparison between Comparative Example 5 and Example 2, it can be seen that Comparative Example 5 does not contain Si, and the electrical conductivity of the aluminum alloy increases, but the hardness decreases, indicating that the strength of Comparative Example 3 will also decrease. Therefore, it is necessary to introduce a certain amount of Si for solid solution and precipitation strengthening.

[0153] From the comparison between Comparative Example 6 and Examples 1 to 4, it can be seen that the Mg and Si contents in Comparative Example 6 are higher than the ranges of the embodiments of the present invention, resulting in an increase in the temperature difference between the liquid and solid phase regions. When the Mg and Si contents are 0.6 wt.%, the temperature difference between the liquid and solid phase regions will exceed 30°C, which will cause more casting defects, including shrinkage and shrinkage cavities, thereby reducing the electrical conductivity of the aluminum alloy. Therefore, the Mg and Si contents must be controlled within the range specified in the embodiments of the present invention.

[0154] From the comparison between Comparative Example 7 and Example 4, it can be seen that the Si content in Comparative Example 7 is much higher than the range of the embodiments of the present invention, resulting in a significant decrease in the electrical conductivity of the aluminum alloy.

[0155] In addition, Figure 5 It is shown that the aluminum alloys of Examples 1-3 have excellent stability of mechanical properties at medium temperature, and their hardness does not decrease significantly after being kept at 180°C for 100 hours.

[0156] In the present invention, the terms "one embodiment", "some embodiments", "examples", "specific examples", or "some examples" mean that the specific features, structures, materials or characteristics described in conjunction with the embodiment or example are included in at least one embodiment or example of the present invention. In this specification, the schematic expressions of the above terms do not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described can be combined in any one or more embodiments or examples in a suitable manner. In addition, those skilled in the art can combine and combine different embodiments or examples described in this specification and the features of different embodiments or examples without contradiction.

[0157] Although the embodiments of the present invention have been shown and described above, it will be understood that the above embodiments are illustrative and are not to be construed as limitations on the present invention. A person skilled in the art may change, modify, replace and modify the above embodiments within the scope of the present invention.

Claims

1. An aluminum alloy, characterized in that: Taking the total mass of the aluminum alloy as 100wt.%, it includes the following components: Fe 1.0-1.2wt.%, Ni 0.8-1.2wt.%, Mg 0.2-0.45wt.%, Si 0.3-0.5wt.%, and the balance is Al and unavoidable impurities, wherein the ratio between the mass percentage of Mg and the mass percentage of Si is (0.7-0.9):

1.

2. The aluminum alloy according to claim 1, characterized in that The mass percentage of Fe is 1.0-1.1 wt.%.

3. The aluminum alloy according to claim 1 or 2, characterized in that The mass percentage of Ni is 0.9-1.1 wt.%.

4. The aluminum alloy according to claim 1, characterized in that The mass percentage of Mg is 0.3-0.45 wt. %; the mass percentage of Si is 0.4-0.5 wt. %.

5. The method for preparing an aluminum alloy according to any one of claims 1 to 4, characterized in that: The following steps are involved: The raw materials of the aluminum alloy are added in proportion and smelted to obtain an aluminum alloy melt; the aluminum alloy melt is refined and degassed, and then cast into a casting mold; after the aluminum alloy melt solidifies and cools, the mold is opened and the cast aluminum alloy is taken out.

6. The method for preparing the aluminum alloy according to claim 5, wherein: Also includes: The as-cast aluminum alloy is heat treated.

7. The method for preparing the aluminum alloy according to claim 6, wherein: The heat treatment includes: annealing the cast aluminum alloy at 240-260° C. for 2-6 hours and taking it out after cooling; or, solutionizing the cast aluminum alloy at 500-540° C. for 3-5 hours, taking it out after cooling, and then keeping it at 160-200° C. for 12-100 hours.

8. The method for preparing the aluminum alloy according to claim 5 or 6, characterized in that: The casting mold was not preheated and kept at room temperature.

9. Use of the aluminum alloy according to any one of claims 1 to 4 or the aluminum alloy obtained by the preparation method according to any one of claims 5 to 8 in vehicles.

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