Semi-solid die-casting high-strength and high-conductivity aluminum alloy and die-casting method thereof

Abstract

The invention discloses a semi-solid die-casting high-strength and high-conductivity aluminum alloy and a die-casting method thereof, and relates to the technical field of semi-solid die-casting aluminum alloys, and the aluminum alloy comprises the following components in parts by weight: 3.86 to 4.32 percent of silicon, 0.24 to 0.32 percent of magnesium, 0.35 to 0.45 percent of copper, 0.42 to 0.56 percent of manganese, 0.26 to 0.38 percent of iron, 0.07 to 0.09 percent of zinc, 0.30 to 0.40 percent of molybdenum, 0.18 to 0.22 percent of strontium, 0.05 to 010 percent of yttrium, 0.03 to 0.05 percent of scandium and the balance of aluminum. The die casting method of the aluminum alloy comprises the steps of raw material smelting, degassing, stirring vibration, die casting, heat treatment and the like. The problems that an existing aluminum alloy is poor in casting fluidity, and a semi-solid die-casting aluminum alloy with high strength and high thermal conductivity cannot be obtained are solved, the tensile strength of the semi-solid die-casting aluminum alloy obtained through the formula and the technology is not lower than 314 MPa, the yield strength is not lower than 263 MPa, the thermal conductivity is not lower than 182 W / (m.K), and the service life of the semi-solid die-casting aluminum alloy is prolonged. And the requirements and application of high-strength and high-thermal-conductivity aluminum alloy parts required in the fields of communication, automobiles, electronic appliances and the like are met.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of semi-solid die-casting aluminum alloy, in particular to a semi-solid die-casting high-strength and high-conductivity aluminum alloy and a die-casting method thereof. BACKGROUND

[0002] The semi-solid die-casting forming process refers to that a liquid metal is subjected to strong stirring in a solidification process, so that a dendritic network skeleton formed by ordinary casting is broken to form a dispersed granular structure, thereby a semi-solid metal liquid is prepared, and then the semi-solid metal liquid is die-cast into a bad material or a casting. Compared with ordinary casting, the semi-solid die-casting has a small solidification shrinkage, and can avoid defects such as shrinkage holes and porosity, so that various types of parts with thinner wall thickness, denser structure and higher mechanical properties can be prepared.

[0003] With the development of the communication field and the 3C field, the miniaturization, integration and energy density of electronic components are continuously improved, and higher requirements are put forward for the heat dissipation capacity of heat dissipation structural parts. Currently, the semi-solid die-casting forming aluminum alloys that can be applied in batches only include 356, 357, 319s, ADC12 and A380, and the thermal conductivity of these aluminum alloys is less than 150 W / m·K, which cannot meet the current product heat dissipation performance requirements. However, aluminum alloys with good thermal conductivity, such as 6061 and 6063, cannot meet the process requirements of semi-solid die-casting due to their poor casting fluidity, and are only suitable for plastic processing methods such as extrusion, rolling and forging. Therefore, it is necessary to develop new types of aluminum alloys for semi-solid die-casting forming process, which can improve the thermal conductivity and meet the heat dissipation performance requirements on the basis of meeting the mechanical properties. SUMMARY

[0004] In view of the problems in the prior art, the main purpose of the present application is to provide a semi-solid die-casting high-strength and high-conductivity aluminum alloy and a die-casting method thereof, which aims to solve the problems that the casting fluidity of the existing aluminum alloy is poor, the mechanical strength and thermal conductivity of the semi-solid die-casting aluminum alloy material obtained cannot be considered, and the high level cannot be achieved.

[0005] In order to achieve the above-mentioned purpose, a semi-solid die-casting high-strength and high-conductivity aluminum alloy disclosed by the present application comprises the following element components in terms of mass percentage:

[0006] Silicon 3.86-4.32%, magnesium 0.24-0.32%, copper 0.35-0.45%, manganese 0.42-0.56%, iron 0.26-0.38%, zinc 0.07-0.09%, molybdenum 0.30-0.40%, strontium 0.18-0.22%, yttrium 0.05-0.10%, scandium 0.03-0.05%. The balance is aluminum and inevitable impurities. The inevitable impurities include calcium (Ca), lead (Pb), vanadium (V), sodium (Na), bismuth (Bi), antimony (Sb), beryllium (Be), etc. The inevitable impurities are not excluded because they are inevitably mixed from raw materials or the surrounding environment in a typical manufacturing process. Since these impurities are known to those skilled in the art during the manufacturing process, all details thereof are not specifically mentioned in the present specification. Since the above-mentioned impurity element components can adversely affect the flowability, mechanical strength, and particularly thermal conductivity of the aluminum alloy, the total amount of the impurity elements is preferably controlled to be 0.05% or less, and more preferably, the total amount of the impurity elements is controlled to be 0.01% or less.

[0007] In the aluminum alloy formulation of the present application, when the content of silicon is within [3.86%, 4.32%], the flowability of the aluminum alloy satisfies the semi-solid die casting requirement, and can form Mg2Si strengthening phase with magnesium element, which is uniformly distributed in the α-Al matrix structure, and helps to improve the mechanical properties of the aluminum alloy. If the addition amount of silicon is less than 3.86%, it is difficult to ensure that the molten metal has sufficient strength and flowability; if the addition amount of silicon exceeds 4.32%, the ductility and thermal conductivity are deteriorated, therefore, in the present application, the addition amount of silicon element is preferably 3.86-4.32%.

[0008] In the aluminum alloy formulation of the present application, when the content of copper is within [0.35%, 0.45%], it can form a solid solution with aluminum, and the precipitated Al2Cu phase is dispersedly distributed on the grain boundary of the aluminum alloy, which is a strengthening phase, and can improve the strength and toughness of the aluminum alloy. If the addition amount of copper is less than 0.35%, the mechanical strength of the aluminum alloy is not sufficiently improved; if the addition amount of copper exceeds 0.45%, the ductility and thermal conductivity are reduced. Therefore, in the present application, the addition amount of copper element is preferably 0.35-0.45%.

[0009] In the aluminum alloy formula of the present application, when the content of iron is within [0.26%, 0.38%], the sticking of the aluminum alloy to the mold can be effectively prevented, and the strength of the alloy during pressure casting can be improved. When the addition amount of iron is less than 0.26%, the anti-sticking effect on the mold cannot be achieved; when the addition amount of iron exceeds 0.38%, coarse needle-shaped Al-Fe-Si rich Fe phases are formed, which can seriously cut the aluminum alloy matrix, resulting in low strength and plasticity of the pressure-cast aluminum alloy, and can also have a great negative impact on the ductility and thermal conductivity of the aluminum alloy. Therefore, in the present application, the addition amount of iron is preferably 0.26-0.38%.

[0010] In the aluminum alloy formula of the present application, when the content of magnesium is within [0.24%, 0.32%], it can form stable Mg2Si compounds with silicon, which can greatly improve the mechanical properties of the aluminum alloy material, and the modification treatment of strontium element can improve the morphology of the strengthening phase, further improving the mechanical properties of the alloy. When the content of magnesium is less than 0.24%, the strengthening effect of magnesium on the aluminum alloy material is insufficient, and the performance improvement is poor; when the content of copper exceeds 0.32%, the solubility of magnesium element in the aluminum alloy is limited, and the precipitation speed is not ideal. Adding too much magnesium can form excess phases between the grains, which can reduce the strength at the grain boundary, thereby causing the aluminum alloy to become brittle and the plasticity to be greatly reduced. In addition, when the content of magnesium is within the above range, it can combine with zinc to form MgZn2 strengthening phases, which are uniformly dispersed at the grain boundaries of the aluminum alloy, and the grain boundaries of the aluminum alloy can be improved, which can ensure the strength and toughness of the pressure-cast aluminum alloy. Therefore, in the present application, the addition amount of magnesium is preferably 0.24-0.32%.

[0011] In the aluminum alloy formula of the present application, when the content of manganese is within [0.42%, 0.56%], it can be dissolved into the aluminum alloy matrix to strengthen the aluminum alloy matrix, and can also inhibit the grain growth of primary Si and alpha-Al, so that the primary Si content is dispersed between the grains to play a role of dispersion strengthening, thereby improving the strength and toughness of the aluminum alloy material. If the content of manganese is less than 0.42%, the performance of the aluminum alloy will not meet the expectation; if the content of manganese is higher than 0.56%, the thermal conductivity and plasticity of the aluminum alloy material can be affected. Therefore, in the present application, the addition amount of manganese is preferably 0.42-0.56%.

[0012] In the aluminum alloy formula of the present application, when the content of zinc is within [0.07%, 0.09%], it can be effectively dissolved in alpha-Al to form a solid solution, play a role in strengthening the mechanical properties of the aluminum alloy, and also can improve the mechanical processing performance of the aluminum alloy and improve the flow forming property of the die-casting aluminum alloy. If the addition amount of zinc element is less than 0.07%, the improvement effect of alloy strength is insufficient; if the addition amount of zinc element exceeds 0.09%, the thermal conductivity of the alloy may be reduced. Therefore, in the present application, the addition amount of zinc element is preferably 0.07-0.09%.

[0013] In the aluminum alloy formula of the present application, when the content of strontium is within [0.18%, 0.22%], it can effectively improve the thermal conductivity and flowability of the aluminum alloy, the addition of strontium element can refine the alpha dendrite and eutectic silicon in the aluminum alloy, and at the same time improve the morphology of the overall organization; if the addition amount of strontium element is less than 0.18%, it is difficult to obtain the effect of improving flowability and thermal conductivity; if the strontium element is excessively added, more than 0.22%, it is easy to cause over modification and aggravate the tendency of hydrogen absorption, and the degassing of the molten metal becomes difficult, which may form brittle Al-Sr compounds. Therefore, in the present application, the addition amount of strontium element is preferably 0.18-0.22%.

[0014] In the aluminum alloy formula of the present application, when the content of molybdenum is within [0.30%, 0.40%], it can generate Mo3Al8 strengthening phase with the matrix Al in the aluminum alloy, and under the synergistic effect of strontium and molybdenum, an aluminum alloy with high strength and good thermal conductivity can be obtained. If the addition amount of molybdenum in the system is less than 0.30%, it will be difficult for the aluminum alloy to achieve the expected effect; if it is higher than 0.40%, it will increase the production cost, and may adversely affect the plasticity and toughness of the aluminum alloy material. Therefore, in the present application, the addition amount of molybdenum element is preferably 0.30-0.40%.

[0015] In the aluminum alloy formula of the present application, when the contents of yttrium and scandium as rare earth elements are controlled within [0.05%, 0.10%] and [0.03%, 0.05%] respectively, it can increase the composition undercooling during the casting of the aluminum alloy, refine the grains, reduce the secondary intergranular spacing, reduce the gas and inclusions in the alloy, and make the inclusions tend to spheroidization, which is beneficial to obtain an aluminum alloy semi-solid slurry with an average grain diameter of less than 50 microns and an average sphericity of the grains of greater than 0.86. In addition, the addition of the above two elements can also reduce the surface tension of the melt, increase the flowability, be beneficial to the die-casting forming, and improve the preparation efficiency of the alloy process. If the contents of yttrium and scandium are too low, they cannot play a good modification effect; naturally, the contents of yttrium and scandium should not be too high, otherwise the production cost will be increased, and more likely the thermal conductivity and mechanical properties will be reduced.

[0016] Another object of the present application is to provide a preparation and die casting process of a semi-solid die casting high-strength and high-conductivity aluminum alloy, and the specific steps are as follows:

[0017] According to the component composition of the semi-solid die casting aluminum alloy, aluminum ingots with a purity of 99.8%, silicon ingots with a purity of 99.9%, iron wires with a purity of 99.9%, magnesium ingots with a purity of 99.95%, zinc ingots with a purity of 99.95%, electrolytic copper with a purity of 99.99%, aluminum-manganese alloy, aluminum-molybdenum alloy, aluminum-strontium alloy, aluminum-yttrium alloy, and aluminum-scandium alloy are selected. The aluminum ingots are first melted at 790±5℃, and then the silicon ingots and iron wires are added to the melt for melting. After the above raw materials are completely melted, the melt temperature is lowered to 740-760℃, and then the magnesium ingots and zinc ingots are added to the melt for melting. After the melting is completed, the melt temperature is finally lowered to 720-740℃, and the remaining intermediate alloy raw materials are added to the melt for melting, and stirring to obtain an aluminum alloy molten liquid.

[0018] Subsequently, the aluminum alloy molten liquid is first deslagged, and then argon is blown into the aluminum alloy molten liquid under the stirring of a graphite rotor to remove gas. During this period, the rotating speed of the graphite rotor is 400 rpm, and the argon flow rate is controlled at 15 L / min. After degassing, the aluminum alloy molten liquid is left to stand for 30 min.

[0019] After that, the aluminum alloy molten liquid is prepared into an aluminum alloy semi-solid slurry with a temperature of 605-625℃ under the condition of stirring and vibration. Specifically, the aluminum alloy molten liquid is first mechanically stirred for 30-40 seconds, and the mechanical stirring speed is set to 700-800 revolutions per minute. Then, the aluminum alloy molten liquid is ultrasonically vibrated for 20-30 seconds, and the ultrasonic vibration frequency is 30-40 kHz. Through the above stirring and vibration, an α-Al grain aluminum alloy semi-solid slurry with an average diameter of less than 50 microns and an average sphericity of greater than 0.86 can be obtained. This aluminum alloy semi-solid slurry has excellent fluidity and is very suitable for semi-solid die casting forming. It is worth noting that the α-Al grain aluminum alloy semi-solid slurry with small size and high sphericity is an important condition for subsequent semi-solid die casting.

[0020] The obtained aluminum alloy semi-solid slurry is transferred to the die casting machine pressure chamber for injection forming, and the die casting temperature is set to 265-275℃, the injection speed is 0.3-0.4 m / s, the injection specific pressure is 60-80 MPa, the solidification pressure holding pressure is 120-140 MPa, and the solidification pressure holding time is 20-30 s, to obtain a semi-solid die casting aluminum alloy crude product. Through the above die casting process, the aluminum alloy semi-solid slurry can be semi-solid die cast into an aluminum alloy, which can meet the forming of various complex-shaped parts, avoid the generation of splashes and the inclusion of gas and inclusions during the filling process, and ensure the quality and performance of the aluminum alloy parts.

[0021] The semi-solid die-casting aluminum alloy crude product is heated for the first time to 505-525℃ for 8 hours, then air-cooled, and cooled to 60-100℃; heated for the second time to 230-250℃ for 4 hours, then air-cooled, and cooled to 60-100℃; heated for the third time to 475-495℃ for 6 hours, then air-cooled, and cooled to 60-100℃, and finally heated to 175-195℃ for 3 hours, and air-cooled to room temperature, to obtain the semi-solid die-casting aluminum alloy of the present application. The above heat treatment process can obtain the desired mechanical strength and thermal conductivity. If the semi-solid die-casting process and the heat treatment aging process are not within the above matching range, the semi-solid die-casting aluminum alloy cannot achieve the desired performance.

[0022] The present application has the following beneficial effects:

[0023] The semi-solid die-casting aluminum alloy of the present application adjusts and optimizes the formula, takes aluminum, silicon, copper, magnesium, and manganese as the main alloying elements, adds zinc, iron, strontium, molybdenum, yttrium, and scandium elements, and controls the amount of each element, so that they cooperate with each other to improve the fluidity during the alloy preparation process, thereby meeting the semi-solid die-casting requirements, and the formed Al2Cu, Mg2Si, MgZn2, Mo3Al8, and other strengthening phases can be uniformly distributed in the α-Al matrix structure and the grain boundary. The added rare earth elements yttrium and scandium can purify the alloy melt and refine the grain. The present application also improves the degassing process, semi-solid slurry forming process, die-casting process, and heat treatment process, increases the fluidity of the melt, improves the casting performance, and effectively improves the mechanical properties and thermal conductivity of the aluminum alloy. Ultimately, the semi-solid die-casting aluminum alloy has high mechanical strength and excellent thermal conductivity. In summary, the semi-solid die-casting aluminum alloy obtained by using the formula and process disclosed in the present application has a tensile strength of not less than 314MPa, a yield strength of not less than 263MPa, and a thermal conductivity of not less than 182W / (m·K), which meets the needs and applications of high-strength and high-thermal-conductivity aluminum alloy parts in the fields of communication, automobiles, electronics, and electrical appliances. DETAILED DESCRIPTION

[0024] The specific embodiments of the present application will be further described below in conjunction with examples, which are only used to more clearly illustrate the technical solutions of the present application and cannot be used to limit the protection scope of the present application.

[0025] Example 1

[0026] The present application discloses a semi-solid die-casting aluminum alloy, and the content of each component is shown in the following table:

[0027] Silicon 3.86%, Magnesium 0.24%, Copper 0.35%, Manganese 0.42%, Iron 0.26%, Zinc 0.07%, Molybdenum 0.30%, Strontium 0.18%, Yttrium 0.05%, Scandium 0.03%, the balance being Aluminum and inevitable impurities.

[0028] The preparation and the die casting process of the semi-solid die casting aluminum alloy of the present example are as follows:

[0029] According to the component composition of the semi-solid die casting aluminum alloy, aluminum ingot with purity of 99.8%, silicon ingot with purity of 99.9%, iron wire with purity of 99.9%, magnesium ingot with purity of 99.95%, zinc ingot with purity of 99.95%, electrolytic copper with purity of 99.99%, aluminum-manganese alloy, aluminum-molybdenum alloy, aluminum-strontium alloy, aluminum-yttrium alloy and aluminum-scandium alloy are selected. The aluminum ingot is first melted at 785℃, then the silicon ingot and the iron wire are added to the melt for melting. After the above raw materials are completely melted, the melt temperature is lowered to 740℃, then the magnesium ingot and the zinc ingot are added to the melt for melting. After the melting is completed, finally the melt temperature is lowered to 720℃, and the remaining intermediate alloy raw materials are added to the melt for melting. After uniform stirring, the aluminum alloy molten liquid is obtained.

[0030] Subsequently, the aluminum alloy molten liquid is first deslagged, then argon is blown into the aluminum alloy molten liquid under the stirring of the graphite rotor for degassing. During the process, the rotating speed of the graphite rotor is 400 rpm, and the argon flow is controlled at 15 L / min. After degassing, the aluminum alloy molten liquid is left for 30 min.

[0031] Then, the aluminum alloy molten liquid is prepared into aluminum alloy semi-solid slurry with a temperature of 605℃ under the condition of stirring and vibration. Specifically, the aluminum alloy molten liquid is first mechanically stirred for 30 seconds, and the mechanical stirring speed is set at 700 revolutions per minute. Then, the aluminum alloy molten liquid is ultrasonically vibrated for 20 seconds, and the ultrasonic vibration frequency is 30 kHz.

[0032] The obtained aluminum alloy semi-solid slurry is transferred to the die casting machine pressure chamber for injection forming. The die casting temperature is set at 265℃, the injection speed is 0.3 m / s, the injection specific pressure is 60 MPa, the solidification holding pressure is 120 MPa, and the solidification holding time is 20 s. The semi-solid die casting aluminum alloy crude product is obtained.

[0033] The semi-solid die casting aluminum alloy crude product is first heated to 505℃ and kept for 8 hours, then air-cooled, and cooled to 65±5℃; secondly heated to 230℃ and kept for 4 hours, then air-cooled, and cooled to 65±5℃; thirdly heated to 475℃ and kept for 6 hours, then air-cooled, and cooled to 65±5℃; finally heated to 175℃ and kept for 3 hours, and air-cooled to room temperature in the furnace. Thus, the semi-solid die casting aluminum alloy of the present example 1, numbered YL01, is obtained.

[0034] Example 2

[0035] The embodiment 2 of the present application discloses a semi-solid die-casting aluminum alloy, the content of each component of the aluminum alloy is expressed by mass percentage as follows:

[0036] Silicon 3.98%, magnesium 0.26%, copper 0.38%, manganese 0.45%, iron 0.28%, zinc 0.07%, molybdenum 0.32%, strontium 0.19%, yttrium 0.06%, scandium 0.03%, and the balance of aluminum and inevitable impurities.

[0037] The preparation and die-casting process of the semi-solid die-casting aluminum alloy of the embodiment are as follows:

[0038] According to the component composition of the semi-solid die-casting aluminum alloy, aluminum ingots with a purity of 99.8%, silicon ingots with a purity of 99.9%, iron wires with a purity of 99.9%, magnesium ingots with a purity of 99.95%, zinc ingots with a purity of 99.95%, electrolytic copper with a purity of 99.99%, aluminum-manganese alloy, aluminum-molybdenum alloy, aluminum-strontium alloy, aluminum-yttrium alloy and aluminum-scandium alloy are selected, the aluminum ingots are first melted at 785 ℃, then the silicon ingots and the iron wires are added to the melt for melting, after the above raw materials are completely melted, the melt temperature is lowered to 745 ℃, the magnesium ingots and the zinc ingots are then added to the melt for melting, after the melting is completed, finally, the melt temperature is lowered to 725 ℃, and the remaining intermediate alloy raw materials are added to the melt for melting, and the aluminum alloy melt is obtained after uniform stirring.

[0039] Subsequently, the aluminum alloy melt is first slagged, and then argon is blown into the aluminum alloy melt under the stirring of a graphite rotor for degassing, during which the rotating speed of the graphite rotor is 400 rpm, and the argon flow is controlled at 15 L / min, and the aluminum alloy melt is placed for 30 min after degassing.

[0040] Then, the aluminum alloy melt is prepared into an aluminum alloy semi-solid slurry with a temperature of 610 ℃ under the condition of stirring and vibration. Specifically, the aluminum alloy melt is first mechanically stirred for 30 seconds, and the mechanical stirring speed is set to 700 revolutions / minute, and then the aluminum alloy melt is ultrasonically vibrated for 20 seconds, and the ultrasonic vibration frequency is 30 kHz.

[0041] The obtained aluminum alloy semi-solid slurry is transferred to the pressure chamber of a die-casting machine for injection forming, the die-casting temperature is set to 265 ℃, the injection speed is 0.3 m / s, the injection specific pressure is 65 MPa, the solidification pressure holding pressure is 125 MPa, and the solidification pressure holding time is 20 s, and a semi-solid die-casting aluminum alloy crude product is obtained.

[0042] The semi-solid die-casting aluminum alloy crude product is heated to 510℃ for the first time, kept for 8 hours, then air-cooled, and cooled to 70±5℃; heated to 235℃ for the second time, kept for 4 hours, then air-cooled, and cooled to 70±5℃; heated to 480℃ for the third time, kept for 6 hours, then air-cooled, and cooled to 70±5℃, finally heated to 180℃, kept for 3 hours, and air-cooled to room temperature in the furnace, to obtain the semi-solid die-casting aluminum alloy of Example 2, numbered YL02.

[0043] Example 3

[0044] The semi-solid die-casting aluminum alloy of Example 3 disclosed in the present application has the following content of each component in mass percentage:

[0045] Silicon 4.12%, magnesium 0.28%, copper 0.40%, manganese 0.49%, iron 0.32%, zinc 0.08%, molybdenum 0.35%, strontium 0.20%, yttrium 0.08%, scandium 0.04%, and the balance of aluminum and inevitable impurities.

[0046] The preparation and die-casting process of the semi-solid die-casting aluminum alloy of the present example are as follows:

[0047] According to the component composition of the semi-solid die-casting aluminum alloy, aluminum ingots with a purity of 99.8%, silicon ingots with a purity of 99.9%, iron wires with a purity of 99.9%, magnesium ingots with a purity of 99.95%, zinc ingots with a purity of 99.95%, electrolytic copper with a purity of 99.99%, aluminum-manganese alloy, aluminum-molybdenum alloy, aluminum-strontium alloy, aluminum-yttrium alloy, and aluminum-scandium alloy are selected. The aluminum ingots are first melted at 790℃, then the silicon ingots and iron wires are added to the melt for melting. After the above raw materials are completely melted, the melt temperature is lowered to 750℃, and the magnesium ingots and zinc ingots are added to the melt for melting. After melting is completed, the melt temperature is finally lowered to 730℃, and the remaining intermediate alloy raw materials are added to the melt for melting, and stirred uniformly to obtain an aluminum alloy molten liquid.

[0048] Subsequently, the aluminum alloy molten liquid is first deslagged, and then argon is blown into the aluminum alloy molten liquid under the stirring of a graphite rotor for degassing. During this period, the rotating speed of the graphite rotor is 400 rpm, and the argon flow rate is controlled at 15 L / min. After degassing, the aluminum alloy molten liquid is left to stand for 30 min.

[0049] After that, the aluminum alloy molten liquid is prepared into an aluminum alloy semi-solid slurry with a temperature of 615℃ under the condition of stirring vibration. Specifically, the aluminum alloy molten liquid is first mechanically stirred for 35 seconds, and the mechanical stirring speed is set at 800 revolutions / minute. Then, the aluminum alloy molten liquid is ultrasonically vibrated for 25 seconds, and the ultrasonic vibration frequency is 35 kHz.

[0050] The obtained semi-solid slurry of aluminum alloy is transferred into the compression chamber of the die casting machine for injection forming, and the die casting temperature is set to 270℃, the injection speed is 0.3m / s, the injection specific pressure is 70MPa, the solidification pressure holding pressure is 130MPa, and the solidification pressure holding time is 25s, to obtain a semi-solid die casting aluminum alloy crude product.

[0051] The semi-solid die casting aluminum alloy crude product is heated to 515℃ for the first time, kept for 8 hours, and then air-cooled to 80±5℃; heated to 240℃ for the second time, kept for 4 hours, and then air-cooled to 80±5℃; heated to 485℃ for the third time, kept for 6 hours, and then air-cooled to 80±5℃; and finally heated to 185℃, kept for 3 hours, and air-cooled to room temperature in the furnace, to obtain the semi-solid die casting aluminum alloy of the example, numbered YL03.

[0052] Example 4

[0053] The example 4 discloses a semi-solid die casting aluminum alloy, and the content of each component is shown as follows in percentage by mass:

[0054] Silicon 4.21%, magnesium 0.30%, copper 0.42%, manganese 0.54%, iron 0.35%, zinc 0.08%, molybdenum 0.38%, strontium 0.21%, yttrium 0.08%, scandium 0.04%, and the balance of aluminum and inevitable impurities.

[0055] The preparation and die casting process of the semi-solid die casting aluminum alloy of the example are as follows:

[0056] According to the composition of the semi-solid die casting aluminum alloy, aluminum ingots with a purity of 99.8%, silicon ingots with a purity of 99.9%, iron wires with a purity of 99.9%, magnesium ingots with a purity of 99.95%, zinc ingots with a purity of 99.95%, electrolytic copper with a purity of 99.99%, aluminum-manganese alloy, aluminum-molybdenum alloy, aluminum-strontium alloy, aluminum-yttrium alloy, and aluminum-scandium alloy are selected, the aluminum ingots are first melted at 790℃, then the silicon ingots and iron wires are added to the melt for melting, after the above raw materials are completely melted, the melt temperature is lowered to 755℃, the magnesium ingots and zinc ingots are added to the melt for melting, after the melting is completed, the melt temperature is finally lowered to 735℃, and the remaining intermediate alloy raw materials are added to the melt for melting, and the melt is stirred uniformly to obtain an aluminum alloy molten liquid.

[0057] Subsequently, the aluminum alloy molten liquid is first slagged, and then argon is blown into the aluminum alloy molten liquid under the stirring of a graphite rotor, during which the rotating speed of the graphite rotor is 400rpm, and the argon flow is controlled to be 15L / min, and after degassing, the aluminum alloy molten liquid is placed for 30min.

[0058] Then the aluminum alloy melt is prepared into an aluminum alloy semi-solid slurry with a temperature of 620℃ under the condition of stirring vibration. Specifically, the aluminum alloy melt is subjected to mechanical stirring for 35 seconds, with a mechanical stirring speed of 800 rpm, and then subjected to ultrasonic vibration for 25 seconds, with an ultrasonic vibration frequency of 35 kHz.

[0059] The obtained aluminum alloy semi-solid slurry is transferred into a die casting machine pressure chamber for injection forming, with a die casting temperature of 270℃, an injection speed of 0.4 m / s, an injection specific pressure of 75 MPa, a solidification pressure holding pressure of 135 MPa, and a solidification pressure holding time of 30 s, to obtain a semi-solid die casting aluminum alloy crude product.

[0060] The semi-solid die casting aluminum alloy crude product is first heated to 520℃ and kept for 8 hours, and then air-cooled to 90±5℃; secondly heated to 245℃ and kept for 4 hours, and then air-cooled to 90±5℃; thirdly heated to 490℃ and kept for 6 hours, and then air-cooled to 90±5℃; and finally heated to 190℃ and kept for 3 hours, and then air-cooled to room temperature to obtain the semi-solid die casting aluminum alloy of the present embodiment, numbered YL04.

[0061] Example 5

[0062] The present embodiment 5 discloses a semi-solid die casting aluminum alloy, the content of each component of the aluminum alloy is expressed as follows in mass percentage:

[0063] Silicon 4.32%, magnesium 0.32%, copper 0.45%, manganese 0.56%, iron 0.38%, zinc 0.09%, molybdenum 0.40%, strontium 0.22%, yttrium 0-10%, scandium 0.05%, and the balance being aluminum and unavoidable impurities.

[0064] The preparation and die casting process of the semi-solid die casting aluminum alloy of the present embodiment are as follows:

[0065] According to the composition of the semi-solid die casting aluminum alloy, aluminum ingots with a purity of 99.8%, silicon ingots with a purity of 99.9%, iron wires with a purity of 99.9%, magnesium ingots with a purity of 99.95%, zinc ingots with a purity of 99.95%, electrolytic copper with a purity of 99.99%, aluminum-manganese alloy, aluminum-molybdenum alloy, aluminum-strontium alloy, aluminum-yttrium alloy, and aluminum-scandium alloy are selected. The aluminum ingots are first melted at 795℃, and then the silicon ingots and iron wires are added to the melt for melting. After the above raw materials are completely melted, the melt temperature is lowered to 760℃, and then the magnesium ingots and zinc ingots are added to the melt for melting. After the melting is completed, the melt temperature is finally lowered to 740℃, and the remaining intermediate alloy raw materials are added to the melt for melting, and the melt is stirred uniformly to obtain an aluminum alloy melt.

[0066] Subsequently, the aluminum alloy molten liquid is first subjected to slagging, and then argon is blown into the aluminum alloy molten liquid under stirring of the graphite rotor to remove gas, during which the rotating speed of the graphite rotor is 400 rpm, and the argon flow rate is controlled to be 15 L / min. After degassing, the aluminum alloy molten liquid is allowed to stand for 30 min.

[0067] Afterwards, the aluminum alloy molten liquid is prepared into an aluminum alloy semi-solid slurry with a temperature of 625℃ under the condition of stirring vibration. Specifically, the aluminum alloy molten liquid is first subjected to mechanical stirring for 40 seconds, and the rotating speed of the mechanical stirring is set to be 800 rpm. Then, the aluminum alloy molten liquid is subjected to ultrasonic vibration for 30 seconds, and the ultrasonic vibration frequency is 40 kHz.

[0068] The obtained aluminum alloy semi-solid slurry is transferred into the compression chamber of a die casting machine for injection forming, and the die casting temperature is set to be 275℃, the injection speed is set to be 0.4 m / s, the injection specific pressure is set to be 80 MPa, the solidification pressure holding pressure is set to be 140 MPa, and the solidification pressure holding time is set to be 30 s. Thus, a semi-solid die casting aluminum alloy crude product is obtained.

[0069] The semi-solid die casting aluminum alloy crude product is first heated to 525℃ and kept for 8 hours, and then air-cooled to 95±5℃. Then, the semi-solid die casting aluminum alloy crude product is second heated to 250℃ and kept for 4 hours, and then air-cooled to 95±5℃. Then, the semi-solid die casting aluminum alloy crude product is third heated to 95℃ and kept for 6 hours, and then air-cooled to 95±5℃. Finally, the semi-solid die casting aluminum alloy crude product is heated to 195℃ and kept for 3 hours, and then air-cooled to room temperature. Thus, a semi-solid die casting aluminum alloy of the present application, numbered YL05, is obtained.

[0070] The present application also sets the following comparative example groups. The semi-solid die casting aluminum alloys of these comparative examples contain element composition contents that are not within the protection scope of the present application, or the die casting processes are not within the protection scope of the present application, or the heat treatment processes are not within the protection scope of the present application.

[0071] Comparative Example 1

[0072] Comparative Example 1 discloses a semi-solid die casting aluminum alloy. Compared with Example 5, only the content of silicon element is different. The content of silicon element in the semi-solid die casting aluminum alloy of Comparative Example 1 is 5.0%.

[0073] The semi-solid die casting aluminum alloy obtained in Comparative Example 1 is numbered D-YL01.

[0074] Comparative Example 2

[0075] Comparative Example 2 discloses a semi-solid die casting aluminum alloy. Compared with Example 5, only the content of magnesium element is different. The content of magnesium element in the semi-solid die casting aluminum alloy of Comparative Example 2 is 0.6%.

[0076] The semi-solid die casting aluminum alloy obtained in Comparative Example 2 is numbered D-YL02.

[0077] Comparative Example 3

[0078] Comparative Example 3 discloses a semi-solid die casting aluminum alloy, compared with Example 1, only the content of copper element is different, the content of copper element of the semi-solid die casting aluminum alloy of Comparative Example 3 is 0.1%.

[0079] The semi-solid die casting aluminum alloy prepared in Comparative Example 3 is numbered as D-YL03.

[0080] Comparative Example 4

[0081] Comparative Example 4 discloses a semi-solid die casting aluminum alloy, compared with Example 1, only the content of manganese element is different, the content of manganese element of the semi-solid die casting aluminum alloy of Comparative Example 4 is 0.1%.

[0082] The semi-solid die casting aluminum alloy prepared in Comparative Example 4 is numbered as D-YL04.

[0083] Comparative Example 5

[0084] Comparative Example 5 discloses a semi-solid die casting aluminum alloy, compared with Example 1, only the content of iron element is different, the content of iron element of the semi-solid die casting aluminum alloy of Comparative Example 5 is 0.1%.

[0085] The semi-solid die casting aluminum alloy prepared in Comparative Example 5 is numbered as D-YL05.

[0086] Comparative Example 6

[0087] Comparative Example 6 discloses a semi-solid die casting aluminum alloy, compared with Example 1, only the content of zinc element is different, the content of zinc element of the semi-solid die casting aluminum alloy of Comparative Example 6 is 0.

[0088] The semi-solid die casting aluminum alloy prepared in Comparative Example 6 is numbered as D-YL06.

[0089] Comparative Example 7

[0090] Comparative Example 7 discloses a semi-solid die casting aluminum alloy, compared with Example 1, only the content of molybdenum element is different, the content of molybdenum element of the semi-solid die casting aluminum alloy of Comparative Example 7 is 0.

[0091] The semi-solid die casting aluminum alloy prepared in Comparative Example 7 is numbered as D-YL07.

[0092] Comparative Example 8

[0093] Comparative Example 8 discloses a semi-solid die casting aluminum alloy, compared with Example 1, only the content of strontium element is different, the content of strontium element of the semi-solid die casting aluminum alloy of Comparative Example 8 is 0.

[0094] The semi-solid die casting aluminum alloy prepared in Comparative Example 8 is numbered as D-YL08.

[0095] Comparative Example 9

[0096] Comparative Example 9 discloses a semi-solid die casting aluminum alloy, compared with Example 1, only the content of yttrium element is different, the content of yttrium element of the semi-solid die casting aluminum alloy of Comparative Example 9 is 0.

[0097] The semi-solid die casting aluminum alloy prepared in Comparative Example 9 is numbered as D-YL10.

[0098] Comparative Example 10

[0099] Comparative Example 10 discloses a semi-solid die casting aluminum alloy, compared with Example 1, only the content of scandium element is different, the content of scandium element of the semi-solid die casting aluminum alloy of Comparative Example 10 is 0.

[0100] The semi-solid die casting aluminum alloy prepared in Comparative Example 10 is numbered as D-YL11.

[0101] Comparative Example 11

[0102] Comparative Example 11 discloses a semi-solid die casting aluminum alloy, compared with Example 3, only the die casting process is different, the die casting process of the aluminum alloy semi-solid slurry of Comparative Example 11 is: the die casting temperature is 250℃, the injection speed is 1m / s, the injection specific pressure is 90MPa, the solidification pressure-keeping pressure is 160MPa, and the solidification pressure-keeping time is 15s.

[0103] The semi-solid die casting aluminum alloy prepared in Comparative Example 11 is numbered as D-YL12.

[0104] Comparative Example 12

[0105] Comparative Example 12 discloses a semi-solid die casting aluminum alloy, compared with Example 3, only the heat treatment process is different, the heat treatment process of the semi-solid die casting aluminum alloy crude product of Comparative Example 12 is:

[0106] The semi-solid die casting aluminum alloy crude product is first solid solution treated at a temperature of 545℃ for 6h, and then water quenched, and then aged at a temperature of 205℃ for 3h.

[0107] The semi-solid die casting aluminum alloy prepared in Comparative Example 12 is numbered as D-YL13.

[0108] Test Example

[0109] The semi-solid die casting aluminum alloys prepared in the examples and comparative examples are subjected to the following performance tests, and the test results are recorded in Table 1 below:

[0110] ①Tensile strength and yield strength: the tensile strength and yield strength test is carried out according to the method disclosed in national standard GB / T 228.1-2010 "Metallic Materials-Tensile Testing-Part 1: Method of Test at Room Temperature".

[0111] ②Thermal conductivity: calculated according to the formula λ = a · p · Cp, wherein a is the thermal diffusivity, measured according to the standard ASTM E1461-01, p is the density, measured according to the method disclosed in the standard GB / T 1423-1996 "Test method for density of precious metals and their alloys", and Cp is the specific heat capacity at constant pressure, measured by a differential scanning calorimeter (DCS).

[0112] Table 1 : Semi-solid die cast aluminum alloy test specimen data for examples and comparative examples

[0113] Subject Tensile strength / MPa Yield strength / MPa Thermal conductivity / W / (m-K) YL01 314 263 185 YL02 321 270 182 YL03 330 289 187 YL04 326 285 186 YL05 317 266 184 D-YL01 249 198 173 D-YL02 265 214 178 D-YL03 270 221 181 D-YL04 261 210 180 D-YL05 262 215 178 D-YL06 258 207 179 D-YL07 254 205 157 D-YL08 263 212 176 D-YL09 275 224 182 D-YL10 278 225 182 D-YL11 246 189 175 D-YL12 229 171 164

[0114] From the recorded and statistical test data in Table 1, it can be seen that the semi-solid die-casting aluminum alloy of the embodiment of the present application has better tensile strength, yield strength and thermal conductivity than the comparative alloy. Specifically, the tensile strength of the semi-solid die-casting aluminum alloy prepared in the embodiment of the present application can reach 314-330 MPa, the yield strength can reach 263-289 MPa, and the thermal conductivity can reach 182-187 W / (m·K). In contrast, the tensile strength (MPa) of the semi-solid die-casting aluminum alloy prepared in the comparative group is in the range of [229, 278], the yield strength (MPa) is in the range of [171, 225], and the thermal conductivity (W / (m·K)) is in the range of [157, 182]. Therefore, from the comparative group, it can be seen that the mechanical properties and thermal conductivity of the semi-solid die-casting aluminum alloy prepared in the present application are affected by the composition of the raw materials, the ratio of the elements and the preparation process. The semi-solid die-casting aluminum alloy prepared by selecting the element composition, ratio of the elements and process parameters within the range has better mechanical properties and thermal conductivity. If the content of each element and the process parameters are not within the protection scope of the present application, or some components deviate from the formula, or the ratio of some element components does not meet the requirements, the mechanical properties and thermal conductivity of the semi-solid die-casting aluminum alloy prepared cannot achieve the expected effect, thereby affecting the performance and application field of the aluminum alloy product.

[0115] The above only describes the preferred embodiments of the present application and is not intended to limit the present application. Although the present application has been described in detail with reference to the foregoing embodiments, those skilled in the art can still modify the technical solutions described in the foregoing embodiments or make equivalent replacements to some technical features. Any modification, equivalent replacement, improvement, etc. made within the spirit and principles of the present application shall be included in the protection scope of the present application.

Claims

1. A semi-solid die-cast high-strength and high-conductivity aluminum alloy, characterized in that: It contains the following ingredients in parts by weight: 3.86-4.32% silicon, 0.24-0.32% magnesium, 0.35-0.45% copper, 0.42-0.56% manganese, 0.26-0.38% iron, 0.07-0.09% zinc, 0.30-0.40% molybdenum, 0.18-0.22% strontium, 0.05-0.10% yttrium, 0.03-0.05% scandium and the balance aluminum.

2. The aluminum alloy according to claim 1, characterized in that The invention comprises the following components in parts by weight: 3.86% silicon, 0.24% magnesium, 0.35% copper, 0.42% manganese, 0.26% iron, 0.07% zinc, 0.30% molybdenum, 0.18% strontium, 0.05% yttrium, 0.03% scandium and the balance aluminum.

3. The aluminum alloy according to claim 1, characterized in that The invention comprises the following components in parts by weight: 3.98% silicon, 0.26% magnesium, 0.38% copper, 0.45% manganese, 0.28% iron, 0.07% zinc, 0.32% molybdenum, 0.19% strontium, 0.06% yttrium, 0.03% scandium and the balance aluminum.

4. The aluminum alloy according to claim 1, characterized in that The invention comprises the following components in parts by weight: 4.12% silicon, 0.28% magnesium, 0.40% copper, 0.49% manganese, 0.32% iron, 0.08% zinc, 0.35% molybdenum, 0.20% strontium, 0.08% yttrium, 0.04% scandium and the balance aluminum.

5. The aluminum alloy according to claim 1, characterized in that The invention comprises the following components in parts by weight: 4.21% silicon, 0.30% magnesium, 0.42% copper, 0.54% manganese, 0.35% iron, 0.08% zinc, 0.38% molybdenum, 0.21% strontium, 0.08% yttrium, 0.04% scandium and the balance aluminum.

6. The aluminum alloy according to claim 1, characterized in that The invention comprises the following components in parts by weight: 4.32% silicon, 0.32% magnesium, 0.45% copper, 0.56% manganese, 0.38% iron, 0.09% zinc, 0.40% molybdenum, 0.22% strontium, 0.10% yttrium, 0.05% scandium and the balance aluminum.

7. A die-casting method of the aluminum alloy according to claim 1, comprising the following steps: Step 1: Select materials and smelt according to the formula; Step 2: The aluminum alloy melt is then deslagging, and then argon is blown into the aluminum alloy melt under stirring by a graphite rotor for degassing. During this period, the speed of the graphite rotor is 400 rpm, and the argon flow rate is controlled at 15 L / min. After degassing, it is allowed to stand for 30 minutes; Step 3: preparing the aluminum alloy melt into an aluminum alloy semi-solid slurry at a temperature of 605-625° C. under stirring and vibration conditions; Step 4: Transfer the obtained semi-solid aluminum alloy slurry to the die-casting machine chamber for injection molding, set the die-casting temperature to 265-275°C, the injection speed to 0.3-0.4 m / s, the injection pressure to 60-80 MPa, the solidification holding pressure to 120-140 MPa, and the solidification holding time to 20-30 s to obtain a semi-solid die-cast aluminum alloy crude product; Step 5: heat treating the semi-solid die-cast aluminum alloy crude product at a temperature of 175-525° C. for 21 hours.

8. The method according to claim 7, characterized in that In the step 1, according to the composition of the semi-solid die-cast aluminum alloy, an aluminum ingot with a purity of 99.8%, a silicon ingot with a purity of 99.9%, an iron wire with a purity of 99.9%, a magnesium ingot with a purity of 99.95%, a zinc ingot with a purity of 99.95%, an electrolytic copper, an aluminum-manganese alloy, an aluminum-molybdenum alloy, an aluminum-strontium alloy, an aluminum-yttrium alloy and an aluminum-scandium alloy are selected, the aluminum ingot is first melted at 790±5°C, and then the silicon ingot and the iron wire are added to the melt to melt. After all the above raw materials are melted, the melt temperature is lowered to 740-760°C, and then the magnesium ingot and the zinc ingot are added to the melt to melt. After the melting is completed, the melt temperature is finally lowered to 720-740°C, and the remaining intermediate alloy raw materials are added to the melt to melt, and stirred evenly to obtain an aluminum alloy melt.

9. The method according to claim 7, characterized in that In the step three, the aluminum alloy melt is first mechanically stirred for 30 to 40 seconds, with the mechanical stirring speed set to 700 to 800 rpm, and then the aluminum alloy melt is ultrasonically vibrated for 20 to 30 seconds, with the ultrasonic vibration frequency being 30 to 40 kHz.

10. The method according to claim 7, characterized in that In the step 5, the semi-solid die-cast aluminum alloy crude product is heated to 505-525°C for the first time, maintained for 8 hours, and then air-cooled to 60-100°C; heated to 230-250°C for the second time, maintained for 4 hours, and then air-cooled to 60-100°C; heated to 475-495°C for the third time, maintained for 6 hours, and then air-cooled to 60-100°C, and finally heated to 175-195°C, maintained for 3 hours, and air-cooled to room temperature with the furnace.