High-strength and high-toughness die-casting aluminum alloy with high thermal conductivity and electric conductivity as well as preparation process and application thereof

Abstract

The invention belongs to the technical field of aluminum alloy materials and preparation thereof, and relates to a high-strength and high-toughness die-casting aluminum alloy and a preparation technology and application thereof.The aluminum alloy comprises Si, Mg, Cu, Mn, Zn, Fe, Cr, Ti, Zr, Sr, Sb, B, La, Ce, Be, P, smaller than or equal to 0.05% of other single elements, smaller than or equal to 0.15% of other impurity elements in total and the balance Al element, the content of Sr and the content of Sb cannot be larger than or equal to 0.005% at the same time, and the balance Al element. According to a singly-cast sample prepared from the high-toughness die-casting aluminum alloy, the tensile strength at the room temperature is 380-450 MPa, the yield strength is 250-350 MPa, the ductility is 3-8%, the brinell hardness is larger than or equal to 105 HB, the electric conductivity is larger than or equal to 19 MS / m, and the heat conductivity is larger than or equal to 140 W / m.K; and at the temperature of 200 DEG C, the tensile strength ranges from 280 MPa to 350 MPa, the yield strength ranges from 220 MPa to 290 MPa, and the ductility ranges from 5% to 10%.

Description

Technical Field

[0001] This invention belongs to the field of aluminum alloy materials and their preparation technology, and relates to a high-strength and high-toughness die-cast aluminum alloy with high thermal and electrical conductivity, its preparation process and application. Background Technology

[0002] Aluminum alloys, with their high specific strength, are the most commonly used lightweight materials and are widely used in automobiles, aircraft, robots, and 3C electronics. With the advent of the intelligent era, the application scenarios of chips and electric drives are increasing. The heat generated by chips and electric drives has become a key factor affecting the stable operation of hardware structures and control systems. Therefore, the requirements for related materials are not only that their yield strength must be higher than 250MPa, but also that their thermal conductivity must be higher than 140W / mK.

[0003] Currently, conventional aluminum alloys, such as A380 and ADC12, have a yield strength of approximately 160 MPa and a thermal conductivity of approximately 100 W / m·K. While patent CN115961186A exhibits a higher yield strength, its thermal conductivity is only around 100 W / m·K. Patent CN111719068A, by incorporating rare and precious elements such as Gd, V, and Ce and employing special smelting and casting processes, achieves a yield strength as high as 220 MPa, but this still cannot meet the ever-increasing market demands.

[0004] To improve thermal conductivity and yield strength, Chinese patent CN114457263A discloses a high-strength, high-toughness, and high-thermal-conductivity die-cast aluminum alloy with the following formula: Si 6~13%, Fe 0.5~1.0%, Cu 0.05~0.45%, Mn 0.08~0.2%, Mg 0.7~1.0%, Zn≤0.3%, Pb≤0.05%, Sr 0.01~0.08%, B 0.006~0.008%, with the balance being Al and a small amount of unavoidable impurities. Its room temperature tensile strength is ≥384MPa, yield strength ≥273MPa, and thermal conductivity ≥176W / (m·K). Although this alloy exhibits good overall performance at room temperature, its composition design primarily relies on the Mg2Si phase as a strengthening phase. The Mg2Si phase undergoes significant coarsening and softening at temperatures exceeding 150℃, potentially leading to a sharp decline in its high-temperature mechanical properties. Furthermore, the local operating temperature of existing high-temperature key components is around 200℃ for a long time, which requires die-cast aluminum alloy materials to not only have excellent room temperature strength and thermal conductivity, but also excellent high-temperature performance.

[0005] Therefore, there is an urgent need to develop a die-cast aluminum alloy that has good overall performance at room temperature and can still maintain high strength, toughness, and high thermal and electrical conductivity at 200℃. Summary of the Invention

[0006] The purpose of this invention is to overcome the shortcomings of the prior art and provide a high thermal and electrical conductivity die-cast high strength and toughness aluminum alloy, its preparation process and application, which has excellent strength and toughness and thermal and electrical conductivity at 200℃, meeting the requirements of high temperature strength and toughness, weight reduction, heat dissipation and electrical conductivity for components in the new generation of automobiles, aircraft, robots and 3C electronics.

[0007] The technical solution adopted by this invention to solve the technical problem is: The first aspect of this invention provides a high-strength and high-toughness die-cast aluminum alloy with high thermal and electrical conductivity, comprising the following elements by weight: Si 7.5-10.5%, Mg 0.5-1.6%, Cu 0.5-1.0%, Mn 0.2-0.6%, Zn 0.01-0.2%, Fe 0.06-0.3%, Cr 0.001-0.1%, Ti 0.001-0.2%, Zr 0.001-0.2%, Sr 0.001-0.06%, Sb 0.001-0.3%, B 0.001-0.03%, La 0.01-0.2%, Ce 0.001-0.2%, Be 0.001-0.005%, and P ≤ 0.0015%. Other individual elements ≤0.05%, total other impurity elements ≤0.15%, the remainder is Al, and the content of Sr and Sb cannot be ≥0.005% simultaneously. The single-cast samples prepared by the die-cast aluminum alloy have the following properties at room temperature: tensile strength 380-450 MPa, yield strength 250-350 MPa, elongation 3-8%, Brinell hardness ≥105HB, electrical conductivity ≥19MS / m, thermal conductivity ≥140W / m·K; and at 200℃: tensile strength 280-350 MPa, yield strength 220-290 MPa, elongation 5-10%.

[0008] Preferably, the formulation comprises, by weight, the following elements: Si 7.8-10.3%, Mg 0.55-1.52%, Cu 0.55-0.96%, Mn 0.23-0.55%, Zn 0.01-0.2%, Fe 0.10-0.28%, Cr 0.003-0.07%, Ti 0.01-0.17%, Zr 0.002-0.12%, Sr 0.001-0.06%, Sb 0.001-0.25%, B 0.003-0.03%, La 0.01-0.15%, Ce 0.011-0.16%, Be 0.0015-0.005%, P ≤ 0.0015%. Other individual elements ≤0.05%, the total of other impurity elements ≤0.15%, the remainder is Al, and the content of Sr and Sb cannot be ≥0.005% at the same time.

[0009] Preferably, the high-strength and high-toughness die-cast aluminum alloy is composed of α (Al) phase, eutectic Si phase, Mg2Si phase, dispersed granular AlSiMnFe(TiVCr) phase, and Al5Cu2Mg8Si6 phase, and also contains one or more of Al7Cu2Mn phase, Al11RE3 phase, Al2Si2Sr phase, Mg3Sb2 phase, and Al2Cu phase.

[0010] Another aspect of the present invention provides a preparation process for a high-strength and high-toughness die-cast aluminum alloy, comprising the following steps: (1) Aluminum alloy melt smelting: According to the formula, 90-95% of Al99.80 aluminum ingots and other raw materials except Mg, Sr and Be are directly put into an electric resistance furnace or reverberatory furnace for melting. The melt is heated to 800-850℃ and held for 30-60 minutes. Then the remaining Al99.80 aluminum ingots are added. The temperature of the alloy melt is adjusted to 720-740℃. Sodium-free refining agent is sprayed in for melt refining and slag removal. Mg9980 and Be and Sr intermediate alloys are immersed in the melt for melting and refined with nitrogen or argon to obtain the alloy melt, which is then cast into aluminum ingots for remelting. (2) Remelt the aluminum ingot obtained in step (1), or directly adjust the alloy melt obtained in step (1) to the casting temperature of 660℃-720℃; control the cooling rate of 200-500℃ / s in the temperature range of 540℃-610℃ during the solidification process of the casting to obtain the casting. (3) Heat treatment of components: The obtained castings are subjected to graded aging vacuum heat treatment. The castings are heated from room temperature to 120-150℃ within 20-40 minutes and held for 5-10 hours. Then, the castings are heated from 120-150℃ to 180-250℃ within 20-40 minutes and held for 1-3 hours to obtain high strength and toughness die-cast aluminum alloy.

[0011] Preferably, the sodium-free refining agent is 1-2% of the melt weight of STJ-A7, and more preferably 1.5‰ of STJ-A7.

[0012] Preferably, the purity of the nitrogen or argon gas is ≥99.999%, and the hydrogen content of the refined melt is ≤0.12mL / 100gAl.

[0013] Preferably, solidification is carried out under vacuum conditions or the ingate speed is controlled to be <1m / s.

[0014] The third aspect of this invention discloses the application of the aforementioned high-strength and high-toughness die-cast aluminum alloy in the fabrication of heat dissipation structural components. This invention resolves the contradiction between "strength enhancement" and "maintaining thermal / electrical conductivity" in high-strength and tough aluminum alloys by synergistically controlling the proportions of various elements, achieving a breakthrough in overall performance. In particular, through the innovative synergistic design and precise control of three trace elements—Sr (strontium), Sb (antimony), and Be (beryllium)—Sr and Be are controlled to not both be ≥0.005%, with Sr as the primary modifier and Sb as a trace auxiliary; or with Sb as the primary modifier and Sr in extremely small amounts. The resulting high-strength and tough die-cast aluminum alloy consists of α (Al) phase, eutectic Si phase, Mg2Si phase, AlSiMnFe(TiVCr) phase, and Al5Cu2Mg8Si6 phase, and also contains Al7Cu2Mn phase and Al... 11 The alloy is composed of one or more of the following phases: RE3, Al2Si2Sr, Mg3Sb2, and Al2Cu. The Mg2Si phase in α(Al) has a solid solution content between 0.8% and 1.3%, achieving solid solution strengthening. Dispersed granular AlSiMnFe(TiVCr) phases contribute to the second-phase strengthening alloy. Sr and Sb refine the eutectic silicon. When the added Sr or Sb exceeds the amount required for complete modification, the excess Sr or Sb does not simply become harmful impurities, but reacts with elements such as Al, Si, and Mg in the matrix, forming finely dispersed Al2Si2Sr or Mg3Sb2 phases on the matrix, achieving a second-phase strengthening alloy. Trace amounts of Be can reduce the non-metallic oxide inclusions Al2MgO4 generated during the molding process by approximately 5 times. The reduction of non-metallic oxide inclusions Al2MgO4 further improves the alloy's thermal and electrical conductivity.

[0015] In summary, the prepared high-strength and high-toughness die-cast aluminum alloy possesses excellent comprehensive properties, including high strength, high toughness, high thermal conductivity, and high electrical conductivity.

[0016] The advantages and beneficial effects of this invention are: This invention relates to a high-strength and high-toughness die-cast aluminum alloy with high thermal and electrical conductivity. At room temperature: tensile strength 380-450 MPa, yield strength 250-350 MPa, elongation 3-8%, Brinell hardness ≥105HB, thermal conductivity ≥140 W / m·K, and electrical conductivity ≥19 MS / m. Especially at 200℃: tensile strength 270-350 MPa, yield strength 210-290 MPa, and elongation 5-10%, meeting the requirements for weight reduction, heat dissipation, and electrical conductivity in next-generation automotive, aircraft, robotics, and 3C electronic components. Attached Figure Description

[0017] Figure 1 Typical metallographic structure of vacuum die-cast specimen of high-strength and tough die-cast aluminum alloy prepared in Example 1.

[0018] Figure 2The image shows the AlSiMgMn phase analysis of the vacuum die-cast specimen of the high-strength and tough die-cast aluminum alloy prepared in Example 1. Detailed Implementation

[0019] The present invention will be further described in detail below through specific embodiments. The following embodiments are merely descriptive and not limiting, and should not be used to limit the scope of protection of the present invention.

[0020] A high-strength and high-toughness die-cast aluminum alloy with high thermal and electrical conductivity, comprising the following elements by weight: Si 7.5-10.5%, Mg 0.5-1.6%, Cu 0.5-1.0%, Mn 0.2-0.6%, Zn 0.01-0.2%, Fe 0.06-0.3%, Cr 0.001-0.1%, Ti 0.001-0.2%, Zr 0.001-0.2%, Sr 0.001-0.06%, Sb 0.001-0.3%, B 0.001-0.03%, La 0.01-0.2%, Ce 0.001-0.2%, Be The alloy composition is as follows: 0.001-0.005%, P≤0.0015%, other individual elements≤0.05%, total other impurity elements≤0.15%, the remainder is Al, and the content of Sr and Sb cannot be ≥0.005% simultaneously. The single-cast samples prepared from the die-cast aluminum alloy exhibit the following properties at room temperature: tensile strength 380-450 MPa, yield strength 250-350 MPa, elongation 3-8%, Brinell hardness ≥105 HB, electrical conductivity ≥19 MS / m, thermal conductivity ≥140 W / m·K; at 200℃: tensile strength 280-350 MPa, yield strength 220-290 MPa, elongation 5-10%.

[0021] Preferably, the formulation comprises, by weight, the following elements: Si 7.8-10.3%, Mg 0.55-1.52%, Cu 0.55-0.96%, Mn 0.23-0.55%, Zn 0.01-0.2%, Fe 0.10-0.28%, Cr 0.003-0.07%, Ti 0.01-0.17%, Zr 0.002-0.12%, Sr 0.001-0.06%, Sb 0.001-0.25%, B 0.003-0.03%, La 0.01-0.15%, Ce 0.011-0.16%, Be 0.0015-0.005%, P≤0.0015%, other single elements≤0.05%, total of other impurity elements≤0.15%, the remainder is Al, and the content of Sr and Sb cannot be ≥0.005% at the same time.

[0022] Preferably, the high-strength and high-toughness die-cast aluminum alloy is composed of α (Al) phase, eutectic Si phase, Mg2Si phase, dispersed granular AlSiMnFe(TiVCr) phase, and Al5Cu2Mg8Si6 phase, and also contains one or more of Al7Cu2Mn phase, Al11RE3 phase, Al2Si2Sr phase, Mg3Sb2 phase, and Al2Cu phase.

[0023] The preparation process of high-strength and high-toughness die-cast aluminum alloys includes the following steps: (1) Melting of aluminum alloy Al99.80 aluminum ingots, accounting for 90-95% of the theoretically calculated feed weight, along with other raw materials except for Mg, Sr, and Be, are directly fed into the resistance furnace or reverberatory furnace according to the theoretically calculated feed amounts. Silicon is replaced with Si22O2, while copper, manganese, and other elements are added as intermediate alloys.

[0024] After all the above raw materials have been melted and dissolved, the melt is heated to 800-850℃ and held for 30-60 minutes to fully alloy.

[0025] Add the remaining Al99.80 aluminum ingots, adjust the temperature of the alloy melt to 720℃, and uniformly spray 1.5‰ of the melt weight of STJ-A7 sodium-free refining agent into the melt for 5-10 minutes. Remove the surface slag from the furnace. Immerse the Mg9980 and Be and Sr master alloys, preheated to above 350℃, into the melt for melting. Refine with nitrogen or argon gas of 99.999% purity or higher to ensure the hydrogen content of the melt is ≤0.12mL / 100gAl, obtaining the alloy melt, which is then cast into aluminum ingots for remelting.

[0026] (2) Solidification and shaping The aluminum ingots obtained in step 1 are remelted, or the alloy melt obtained in step 1 is directly adjusted to a casting temperature of 660℃-720℃. The cooling rate during the solidification process of the casting is controlled to reach 200-500℃ / s in the temperature range of 540℃-610℃ to obtain the casting. (3) Heat treatment of components: The obtained castings are subjected to graded aging vacuum heat treatment. The castings are heated from room temperature to 120-150℃ within 20-40 minutes and held for 5-10 hours. Then, the castings are heated from 120-150℃ to 180-250℃ within 20-40 minutes and held for 1-3 hours to obtain high strength and toughness die-cast aluminum alloy.

[0027] When the casting is subsequently subjected to a heat treatment process above 490℃, it should be solidified under vacuum conditions or the ingate speed should be less than 1m / s to avoid too much air entrapment caused by turbulence during the filling process. This air entrapment can lead to bulging on the surface of the casting or enlargement of internal pores after expansion at high temperatures, which cannot be reversed and will reduce the various properties of the alloy.

[0028] Example 1 A preparation process for a high-strength and high-toughness die-cast aluminum alloy with high thermal and electrical conductivity is disclosed. The formulation of the high-strength and high-toughness die-cast aluminum alloy is shown in Table 1, and the steps are as follows: (1) Melting of aluminum alloy According to the formula in Table 1, 95% Al99.80 aluminum ingots and other raw materials except for Mg, Sr, and Be are directly fed into the resistance furnace or reverberatory furnace according to the theoretically calculated feed amounts. Silicon is replaced with Si22O2, while copper, manganese, and other elements are added as intermediate alloys.

[0029] After all the above raw materials are melted, the melt is heated to 850℃ and held for 60 minutes to fully alloy.

[0030] Add the remaining 5% of Al99.80 aluminum ingots, adjust the temperature of the alloy melt to 720℃, and uniformly spray 1.5‰ of the melt weight of STJ-A7 sodium-free refining agent into the alloy melt for 10 minutes. Remove the surface slag from the furnace. Immerse the Mg9980 and Be and Sr master alloys, which have been preheated to above 350℃, into the melt for melting. Refine with nitrogen or argon gas of 99.999% purity or higher to ensure that the hydrogen content of the melt is ≤0.12mL / 100g Al, and cast the alloy melt into aluminum ingots for remelting.

[0031] (2) Solidification and shaping The alloy melt obtained in step 1 is directly adjusted to a casting temperature of 660-720℃, and the cooling rate during the solidification process of the casting is controlled to reach 200-500℃ / s to obtain the casting. (3) Heat treatment of components: The obtained castings are subjected to graded aging vacuum heat treatment. The castings are heated from room temperature to 130°C within 30 minutes and held for 8 hours. Then, the castings are heated from 130°C to 200°C within 30 minutes and held for 3 hours to obtain high strength and toughness die-cast aluminum alloy.

[0032] Typical metallographic structure of vacuum die-cast specimens of high-strength and high-toughness die-cast aluminum alloy prepared in Example 1, through... Figure 1 It can be seen that all Mg elements are dissolved in α(Al) in the form of Mg₂Si, resulting in solid solution strengthening; through Figure 2 It can be seen that the fine AlSiMnFe(TiVCr) phase, Al2Si2Sr phase, and Mg3Sb2 phase are dispersed at the micro-nano scale, which not only form a second phase reinforcement but also ensure the elongation.

[0033] Examples 2-6 The only difference from Example 1 is the element content, as shown in Table 1.

[0034] Comparative Example 1 The only difference from Example 1 is that it does not contain Be, as shown in Table 1.

[0035] Comparative Example 2 The only difference from Example 1 is that the elemental formula is the same as A380, as detailed in Table 1.

[0036] Comparative Example 3 The only difference from Example 1 is that the elemental formulation is different, and the contents of Sr and Sb are both greater than 0.005%, as detailed in Table 1.

[0037] Comparative Example 4 The only difference from Example 1 is that step (3) is different. The casting is heated from room temperature to 110°C within 30 minutes, held for 8 hours, and then heated from 110°C to 200°C within 30 minutes, held for 3 hours, to obtain a high-strength and tough die-cast aluminum alloy.

[0038] Comparative Example 5 The only difference from Example 1 is that step (3) is different. The casting is heated from room temperature to 130°C within 30 minutes, held for 8 hours, and then heated from 130°C to 260°C within 30 minutes and held for 3 hours to obtain a high-strength and tough die-cast aluminum alloy.

[0039] Comparative Example 6 The only difference from Example 1 is that the Be content is 0.006%.

[0040] The high-strength and high-toughness die-cast aluminum alloys prepared in the examples and comparative examples were used to prepare vacuum die-cast specimens: The mechanical properties of the tested examples and comparative examples at room temperature and 200℃ were determined using GB / T228.1-2021 Metallic materials, tensile testing—Part 1: Test method at room temperature and GB / T 4338-2006 Metallic materials, high temperature tensile testing method. The results are shown in Table 1.

[0041] The thermal conductivity and electrical conductivity of aluminum and aluminum alloys were tested using the eddy current test method of GB / T12966-2022. The results are shown in Table 1.

[0042] The Al2MgO4 content of the remelted components of the examples and comparative examples was tested using the PoDFA method, and the results are shown in Table 1.

[0043] Table 1. Elemental formulations and performance parameters of the examples and comparative examples.

[0044] The single-cast specimens prepared in Examples 1-6 exhibit the following characteristics at room temperature: tensile strength 380-450 MPa, yield strength 250-350 MPa, elongation 3-8%, Brinell hardness ≥105 HB, electrical conductivity ≥19 MS / m, and thermal conductivity ≥140 W / m·K. At 200℃: tensile strength 280-350 MPa, yield strength 220-290 MPa, and elongation 5-10%.

[0045] Compared to the sample without Be, the Al2MgO4 inclusion defect in the alloy increased by 5 times. The inclusions disrupted the alloy and formed stress concentration, resulting in a significant decrease in the elongation of the sample by about 40% and a decrease in tensile strength by about 7%. Due to the low electrical conductivity of the inclusions themselves and the scattering of electrons, the thermal conductivity and electrical conductivity also decreased slightly.

[0046] Comparative Example 2 is the A380 alloy. Although it has a higher Cu content, its mechanical properties and thermal and electrical conductivity are significantly reduced due to the low Mg content in the alloy, the small effect of solid solution strengthening and aging strengthening, and the influence of coarse needle-like eutectic silicon and AlSiFeMn phase.

[0047] In Comparative Example 3, the contents of Sr and Sb were both ≥0.005%, because Sr and Sb preferentially formed AlMgSrSb compounds, which weakened the modification of eutectic silicon and the dispersion strengthening effect of Al2Si2Sr phase and Mg3Sb2 phase, resulting in reduced performance.

[0048] The heat treatment temperature of Comparative Example 4 decreased because the temperature of the first-stage aging was low, resulting in insufficient aging precipitation and a slight reduction in various properties.

[0049] In Comparative Example 5, the heat treatment temperature increased because the second-stage aging temperature was high, causing the precipitated phase to aggregate and grow, resulting in reduced mechanical properties and slightly higher thermal and electrical conductivity.

[0050] In Comparative Example 6, the Be content was 0.006%. Although the Be content was increased, the performance improvement was not significant. Because Be is a valuable element and a substance with a certain degree of toxicity, higher addition amounts should be avoided as much as possible when increasing the content does not have a noticeable effect.

[0051] The above description is only a preferred embodiment of the present invention. It should be noted that for those skilled in the art, several modifications and improvements can be made without departing from the inventive concept, and these all fall within the protection scope of the present invention.

Claims

1. A high-strength and high-toughness die-cast aluminum alloy with high thermal and electrical conductivity, characterized in that, By weight, its formula includes the following elements in the following amounts: Si 7.5-10.5%, Mg 0.5-1.6%, Cu 0.5-1.0%, Mn 0.2-0.6%, Zn 0.01-0.2%, Fe 0.06-0.3%, Cr 0.001-0.1%, Ti 0.001-0.2%, Zr 0.001-0.2%, Sr 0.001-0.06%, Sb 0.001-0.3%, B 0.001-0.03%, La 0.01-0.2%, Ce 0.001-0.2%, Be The high-strength and high-toughness die-cast aluminum alloy has the following properties: 0.001-0.005%, P≤0.0015%, other individual elements≤0.05%, total other impurity elements≤0.15%, the remainder being Al, and the content of Sr and Sb cannot be ≥0.005% simultaneously. The single-cast specimens prepared from this high-strength and high-toughness die-cast aluminum alloy exhibit the following properties at room temperature: tensile strength 380-450 MPa, yield strength 250-350 MPa, elongation 3-8%, Brinell hardness ≥105 HB, electrical conductivity ≥19 MS / m, thermal conductivity ≥140 W / m·K; at 200℃: tensile strength 280-350 MPa, yield strength 220-290 MPa, elongation 5-10%.

2. The high-strength and high-toughness die-cast aluminum alloy according to claim 1, characterized in that, By weight, its formula includes the following elements in the following amounts: Si 7.8-10.3%, Mg 0.55-1.52%, Cu 0.55-0.96%, Mn 0.23-0.55%, Zn 0.01-0.2%, Fe 0.10-0.28%, Cr 0.003-0.07%, Ti 0.01-0.17%, Zr 0.002-0.12%, Sr 0.001-0.06%, Sb 0.001-0.25%, B 0.003-0.03%, La 0.01-0.15%, Ce 0.011-0.16%, Be 0.0015-0.005%, P≤0.0015%, other single elements≤0.05%, total of other impurity elements≤0.15%, the remainder is Al, and the content of Sr and Sb cannot be ≥0.005% at the same time.

3. The high-strength and high-toughness die-cast aluminum alloy according to claim 1, characterized in that, The high-strength and high-toughness die-cast aluminum alloy is composed of α (Al) phase, eutectic Si phase, Mg2Si phase, dispersed granular AlSiMnFe(TiVCr) phase, and Al5Cu2Mg8Si6 phase, and also contains one or more of Al7Cu2Mn phase, Al11RE3 phase, Al2Si2Sr phase, Mg3Sb2 phase, and Al2Cu phase.

4. A preparation process for a high-strength and high-toughness die-cast aluminum alloy as described in any one of claims 1-3, characterized in that, The steps are as follows: (1) Aluminum alloy melt smelting: According to the formula, 90-95% of Al99.80 aluminum ingots and other raw materials except Mg, Sr and Be are directly put into an electric resistance furnace or reverberatory furnace for melting. The melt is heated to 800-850℃ and held for 30-60 minutes. Then the remaining Al99.80 aluminum ingots are added. The temperature of the alloy melt is adjusted to 720-740℃. Sodium-free refining agent is sprayed in for melt refining and slag removal. Mg9980 and Be and Sr intermediate alloys are immersed in the melt for melting and refined with nitrogen or argon to obtain the alloy melt, which is then cast into aluminum ingots for remelting. (2) Remelt the aluminum ingot obtained in step (1), or directly adjust the alloy melt obtained in step (1) to the casting temperature of 660℃-720℃; control the cooling rate of 200-500℃ / s in the temperature range of 540℃-610℃ during the solidification process of the casting to obtain the casting. (3) Heat treatment of components: The obtained castings are subjected to graded aging vacuum heat treatment. The castings are heated from room temperature to 120-150℃ within 20-40 minutes and held for 5-10 hours. Then, the castings are heated from 120-150℃ to 180-250℃ within 20-40 minutes and held for 1-3 hours to obtain high strength and toughness die-cast aluminum alloy.

5. The preparation process according to claim 4, characterized in that, The sodium-free refining agent is STJ-A7 at 1-2‰ of the melt weight.

6. The preparation process according to claim 4, characterized in that, The purity of the nitrogen or argon gas is ≥99.999%, and the hydrogen content of the refined melt is ≤0.12ml / 100g Al.

7. The preparation process according to claim 4, characterized in that, Solidification is carried out under vacuum conditions or the ingate speed is controlled to be <1m / s.

8. The application of a high-strength and high-toughness die-cast aluminum alloy as described in any one of claims 1-3 or a high-strength and high-toughness die-cast aluminum alloy obtained by the preparation process according to claims 4-7 in the preparation of heat dissipation structural components.

Images