CN108165842B - A kind of semisolid pressure casting high thermal conductivity aluminium alloy and its pressure casting method - Google Patents

Abstract

A kind of semisolid pressure casting high thermal conductivity aluminium alloy and its pressure casting method, the ingredient and mass percent of the aluminium alloy are as follows: Si 6.6~7.4%, Mg 0.15~0.25%, Ti 0.03~0.05%, Cr 0.05~0.1%, Yb 0.01~0.02%, Te 0.01~0.03%, Be 0.05~0.1%, Fe≤0.15%, surplus are Al and inevitable other impurity elements.Pressure casting method includes ingredient, smelting aluminium alloy liquid, prepares semi solid slurry, semisolid pressure casting and solid-solution and aging heat treatment.The present invention passes through the content of optimization Si, Mg main alloying element, refinement α-Al crystal grain, rotten richness Fe phase and common reciever, enable aluminum alloy to that there is high thermal conductivity, high intensity and excellent Semi-solid Thixo-Casting performance, it is suitable for the various components more demanding to heat dissipation performance of semisolid pressure casting, such as wireless communication base station shell, heat-radiating substrate, electronic equipment casing, electrical heating disc.

Description

A semi-solid die-casting high thermal conductivity aluminum alloy and its die-casting method

technical field

The invention belongs to the technical field of aluminum alloy die-casting, and in particular relates to a semi-solid die-casting aluminum alloy with high thermal conductivity and a die-casting method thereof.

Background technique

Aluminum alloy has the characteristics of light weight, good strength and toughness, corrosion resistance and unique metallic luster, and is widely used in electronic appliances, communication equipment, lighting devices, power tools, new energy vehicles and other fields, such as smart phones, notebook computers, tablet computers Shells of electronic products, heat dissipation backplanes and lampshades of LED lights, heat dissipation substrates, filters and cabinet shells of wireless communication base stations, heating plates of rice cookers, induction cookers, water heaters, power battery shells of new energy vehicles, control power supply boxes, drive Motor housing, etc. With the continuous increase of the power of various heating devices, in order to meet the heat dissipation requirements of the heating devices, the thermal conductivity of aluminum alloys is also required to be higher and higher.

Semi-solid die-casting is a technology for die-casting a semi-solid slurry composed of spherical solid phase grains suspended in a liquid phase. Since the semi-solid slurry is different from the solid-liquid mixed slurry formed by the solidification of traditional dendrites, semi-solid die-casting The technology has the following advantages: (1) Due to the good fluidity of the semi-solid slurry, semi-solid die-casting can form various parts with complex shapes; (2) Since the viscosity of the semi-solid slurry is higher than that of liquid metal, the semi-solid die-casting Die-casting can avoid metal splashing and gas entrapment during filling, and semi-solid die-castings can be heat-treated to further improve their mechanical properties; (3) Since the temperature of semi-solid slurry is lower than that of liquid metal, the filling temperature of semi-solid die-casting is low , can reduce the thermal shock to the die-casting mold and improve the service life of the die-casting mold; (4) Since the semi-solid slurry already has some solid phase grains, the solidification shrinkage rate of the semi-solid die-casting is small, which can avoid shrinkage cavity, looseness, Various parts with thinner wall thickness, denser structure and higher mechanical properties can be obtained by eliminating defects such as sticking mold.

The unique technical advantages of semi-solid die-casting are very suitable for the production of various aluminum alloy cooling parts in the fields of electronic appliances, communication equipment, lighting devices, electric tools, and new energy vehicles. However, the existing semi-solid die-casting aluminum alloys are mainly Al-Si cast aluminum alloys such as A356 and ADC12. These grades of cast aluminum alloys have good casting fluidity and machinability due to their high content of Si. , but the thermal conductivity is generally poor. For example, the highest thermal conductivity of A356 cast aluminum alloy is only 120W/(m·K), while the highest thermal conductivity of ADC12 cast aluminum alloy is only 100W/(m·K). It is difficult for alloys to meet the rapid heat dissipation function requirements of various heat-generating devices.

Typical grades of Al-Mg-Si aluminum alloys commonly used in the field of deformed aluminum alloy processing are 6061, 6063, etc. These grades of wrought aluminum alloys have good thermal conductivity because the Si content is usually less than 0.8%, and the Mg content is usually less than 1.2%, and their thermal conductivity is usually higher than 180W/(m K). Up to 185W/(m·K), while the thermal conductivity of 6063 aluminum alloy can reach 190W/(m·K). Although these grades of deformed aluminum alloys have good thermal conductivity, due to the low content of Si, the casting fluidity of these grades of deformed aluminum alloys is very poor, which cannot meet the process requirements of semi-solid die-casting, and is only suitable for extrusion, Plastic processing methods such as rolling and forging.

Contents of the invention

The object of the present invention is to address the above problems and deficiencies, and provide a semi-solid die-casting high thermal conductivity aluminum alloy and a die-casting method that can meet the production needs of various semi-solid die-casting aluminum alloy parts for radiators.

Technical scheme of the present invention is realized like this:

The semi-solid die-casting high thermal conductivity aluminum alloy of the present invention is characterized in that: the aluminum alloy is made by semi-solid die-casting technology, and is composed of the following components in mass percentage: Si 6.6-7.4%, Mg 0.15-0.25%, Ti 0.03 ～0.05%, Cr 0.05～0.1%, Yb 0.01～0.02%, Te 0.01～0.03%, Be 0.05～0.1%, Fe ≤0.15%, the balance is Al and other unavoidable impurity elements, among which Cr and Yb The mass ratio of the impurity element is 5:1, and the single content of other impurity elements is less than 0.05%, and the total content is less than 0.15%.

The die-casting method of the semi-solid die-casting high thermal conductivity aluminum alloy of the present invention is characterized in that it comprises the following steps:

The first step: according to the composition mass percentage of the aluminum alloy, Al10Ti alloy, Al5Cr1Yb alloy, Al5Te alloy, Al5Be alloy and aluminum ingot with a purity of 99.7%, 99.9% instant silicon and 99.95% magnesium ingot are selected as raw materials for batching;

The second step: heating and melting the aluminum ingot at 700-750°C, and then adding 6.6-7.4% of instant silicon, 0.15-0.25% of magnesium ingot, 0.3-0.5% of Al10Ti alloy, 1-2% of the total weight of raw materials Al5Cr1Yb alloy, 0.2-0.6% Al5Te alloy and 1-2% Al5Be alloy are stirred and melted into aluminum alloy liquid;

Step 3: After refining and degassing and removing slag from the aluminum alloy liquid, the aluminum alloy liquid is prepared at a temperature of 620～640℃ aluminum alloy semi-solid slurry;

Step 4: In the mold cavity, the temperature is 100-150 °C, the injection speed is 0.5-1 m/s, the injection specific pressure is 60-80 MPa, the boost pressure is 90-120 MPa and the pressure holding time is 4-6 Under the condition of seconds, the aluminum alloy semi-solid slurry is semi-solid die-casted into aluminum alloy;

Step 5: Solid solution treat the semi-solid die-cast aluminum alloy at 520-530°C for 12-14 hours, after water quenching, aging treatment at 175-185°C for 6-8 hours, and obtain a semi-solid die-casting aluminum alloy after cooling in the furnace. Thermally conductive aluminum alloy, the thermal conductivity of the semi-solid die-casting high thermally conductive aluminum alloy is greater than 160W/(m·K), the tensile strength is greater than 260MPa, and the elongation is greater than 8%.

Compared with the prior art, the present invention has the following advantages:

(1) The present invention improves the thermal conductivity of the semi-solid die-casting aluminum alloy by reducing the content of Si and Mg, and further improves the semi-solid die-casting aluminum alloy by refining the spheroidized α-Al grains, refining the metamorphic iron-rich phase and the eutectic Si phase. The fluidity, strength and plasticity of die-casting aluminum alloy make semi-solid die-casting aluminum alloy have high thermal conductivity, high strength and excellent semi-solid die-casting performance;

(2) The present invention obtains an aluminum alloy semi-solid slurry with an average grain diameter of less than 50 microns and an average grain sphericity greater than 0.8 by optimizing the preparation process of the aluminum alloy semi-solid slurry and the semi-solid die-casting process, thereby further improving the performance of the aluminum alloy semi-solid slurry. Excellent semi-solid die-casting performance, meeting the semi-solid die-casting requirements of radiator parts with complex shapes;

(3) The thermal conductivity of the semi-solid die-casting high thermal conductivity aluminum alloy of the present invention is greater than 160W/(m·K), the tensile strength is greater than 260MPa, and the elongation is greater than 8%. It has the advantages of good thermal conductivity, high strength and good plasticity, It is suitable for semi-solid die-casting of various aluminum alloy parts that require high heat dissipation performance, such as electronic product casings, wireless communication base station casings, electrical heating plates, power battery casings for new energy vehicles, etc.

Detailed ways

The significance of composition and the reason for limiting the content range of the semi-solid die-casting aluminum alloy with high thermal conductivity in the present invention will be described below.

The semi-solid die-casting high thermal conductivity aluminum alloy of the present invention is composed of the following components in mass percentage: Si 6.6-7.4%, Mg 0.15-0.25%, Ti 0.03-0.05%, Cr 0.05-0.1%, Yb 0.01-0.02% , Te 0.01～0.03%, Be 0.05～0.1%, Fe ≤0.15%, the balance is Al and other unavoidable impurity elements, wherein, the mass ratio of Cr to Yb is 5:1, and the individual content of other impurity elements is less than 0.05 %, the total amount is less than 0.15%.

Si can form Al+Si eutectic liquid phase with Al in aluminum alloy, improve the die-casting fluidity of aluminum alloy, and can also improve the strength and machinability of aluminum alloy at the same time. The higher the Si content, the more the eutectic liquid phase, and the better the die-casting fluidity of the aluminum alloy, but the thermal conductivity and plasticity of the aluminum alloy will gradually decrease. When the Si content is less than 6.6%, the fluidity of the aluminum alloy cannot meet the process requirements of semi-solid die-casting, and when the Si content exceeds 7.4%, the thermal conductivity of the aluminum alloy will decrease significantly, and the thermal conductivity cannot reach the required 160 W /(m·K). Therefore, in order to ensure that the aluminum alloy has sufficient die-casting fluidity and thermal conductivity, the Si content is selected at 6.6-7.4%.

Mg can form Mg ₂ Si strengthening phase with Si in semi-solid die-casting aluminum alloy to enhance the strength of semi-solid die-casting aluminum alloy. The higher the Mg content, the higher the strength of semi-solid die-casting aluminum alloy, but the thermal conductivity will gradually decrease. The Mg content is less than 0.15%, the strength of the semi-solid die-casting aluminum alloy cannot reach 260MPa, and the Mg content exceeds 0.25%, which will lead to a significant decrease in the thermal conductivity of the aluminum alloy, and the thermal conductivity cannot reach the required 160 W/(m· K). Therefore, in order to ensure the strength and thermal conductivity of the semi-solid die-casting aluminum alloy, the Mg content is selected at 0.15-0.25%.

Ti mainly plays the role of refining α-Al grains in the semi-solid die-casting aluminum alloy, improving the uniformity of the structure and composition of the aluminum alloy, and improving the fluidity, strength and plasticity of the semi-solid die-casting aluminum alloy. Ti content is less than 0.03%, the effect of grain refinement is not obvious. The higher the Ti content, the better the grain refinement effect, but when the Ti content exceeds 0.05%, it will also lead to a significant decrease in the thermal conductivity of the aluminum alloy. Therefore, the Ti content is selected at 0.03-0.05%.

Cr and Yb are added to the semi-solid die-casting aluminum alloy in the form of Al5Cr1Yb alloy, and the main function is to refine and modify the Fe-rich phase. Fe is an unavoidable impurity element in aluminum alloys. In aluminum alloys, it is usually distributed in the aluminum alloy matrix in the form of coarse acicular Fe-rich phases. The coarse acicular Fe-rich phases will severely split the aluminum alloy matrix, which is the cause of traditional cast aluminum alloys. The main reason for low strength, especially low plasticity. The inventors have found through a large number of experimental studies that the addition of Cr element or Yb element alone can inhibit the growth of the coarse acicular Fe-rich phase, but neither can completely eliminate the coarse acicular Fe-rich phase. The study found that when 0.05-0.1% of Cr elements and 0.01-0.02% of Yb elements are added in combination, and the mass ratio of Cr to Yb is 5:1, the Fe-rich phase can be refined and modified through the interaction of Cr and Yb. , can completely inhibit the growth of the Fe-rich phase in the needle-like direction, transform the Fe-rich phase from coarse needle-like to fine and uniform granular, eliminate the influence of Fe-rich relative to the strength and plasticity of the aluminum alloy, and significantly improve the strength of the semi-solid die-casting aluminum alloy and plasticity. When the content of Cr element is less than 0.05%, or the content of Yb element is less than 0.01%, or the mass ratio of Cr to Yb is not 5:1, the coarse acicular Fe-rich phase cannot be completely eliminated. Therefore, the addition amount of Al5Cr1Yb alloy is selected to be 1-2%, and the aluminum alloy contains 0.05-0.1% Cr and 0.01-0.02% Yb.

The main function of Te in semi-solid die-casting aluminum alloy is to refine the modified eutectic Si phase and improve the fluidity, strength and plasticity of semi-solid die-casting aluminum alloy. The eutectic Si phase in aluminum alloy is usually distributed in the aluminum alloy matrix in the form of coarse flakes. This coarse flake eutectic Si phase will severely split the aluminum alloy matrix, which leads to the low strength of the traditional Al-Si cast aluminum alloy. Especially the important reason for low plasticity. In the prior art, Na or Sr elements are usually added to refine and modify the eutectic Si phase, but the refining and modifying effect of Na is unstable, and it is easy to cause the problem of "sodium embrittlement". It will cause the aluminum alloy melt to get gas. The inventor found after a large number of experimental studies that the Te element is an effective refinement and modification element of the eutectic Si phase of the semi-solid die-casting aluminum alloy of the present invention, which can avoid the poor stability, "sodium brittleness", gas absorption, etc. of the traditional Na and Sr elements. question. Adding 0.01-0.03% Te element can change the form of eutectic Si in semi-solid die-casting aluminum alloy from coarse sheet to fine and uniform granular or fibrous, which can significantly improve the fluidity, strength and plasticity of semi-solid die-casting aluminum alloy. .

The main function of Be in semi-solid die-casting aluminum alloy is to promote the spheroidization of α-Al grains. The higher the sphericity of α-Al grains, the better the fluidity of aluminum alloy semi-solid slurry, and the more suitable for semi-solid die-casting. The traditional method of preparing aluminum alloy semi-solid slurry mainly obtains α-Al grains with higher sphericity by increasing the stirring speed or prolonging the stirring time. The inventors have found through a large number of experimental studies that the Be element is a surface active element, adding 0.05-0.1% of the Be element can significantly promote the spheroidization process of the semi-solid die-casting aluminum alloy α-Al grains of the present invention. Under the preparation process conditions, the semi-solid die-casting aluminum alloy can obtain α-Al grains with higher sphericity, and the fluidity of the semi-solid die-casting aluminum alloy can be significantly improved.

The die-casting method of the semi-solid die-casting high thermal conductivity aluminum alloy according to the present invention and the reasons for limiting the process parameters will be described below.

The die-casting method of semi-solid die-casting high thermal conductivity aluminum alloy according to the present invention is characterized in that it comprises the following steps:

The first step: according to the composition mass percentage of the aluminum alloy, select aluminum ingots with a purity of 99.7%, instant silicon with a purity of 99.9%, magnesium ingots with a value of 99.95%, Al10Ti alloys, Al5Cr1Yb alloys, Al5Te alloys and Al5Be alloys as raw materials for batching;

Step 2: Heat and melt the aluminum ingot at 700-750°C, add 6.6-7.4% of instant silicon, 0.15-0.25% of magnesium ingot, 0.3-0.5% of Al10Ti alloy, 1-2% of the total weight of raw materials Al5Cr1Yb alloy, 0.2-0.6% Al5Te alloy and 1-2% Al5Be alloy are stirred and melted into aluminum alloy liquid;

The higher the purity of the aluminum alloy, the better the thermal conductivity. Fe, Cu, Zn, Ni, Li, Mn, Zr, Sr, Sc, Er, Sn, Pb and other elements are common impurity elements in aluminum ingots, instant silicon, and magnesium ingots. These impurity elements will not only deteriorate The mechanical properties of aluminum alloy, more importantly, will reduce the thermal conductivity of aluminum alloy. Therefore, these impurity elements must be strictly controlled. The present invention can control the content of the impurity element Fe below 0.15% by selecting aluminum ingots with a purity of 99.7%, instant silicon with a purity of 99.9%, and magnesium ingots with a purity of 99.95% as the main raw materials. Cu, Zn, Ni, Li, Mn, The single content of Zr, Sr, Sc, Er, Sn, Pb and other impurity elements is less than 0.05%, and the total content is less than 0.15%, which ensures high thermal conductivity and excellent mechanical properties of semi-solid die-casting aluminum alloy;

Step 3: After refining and degassing and removing slag from the aluminum alloy liquid, the aluminum alloy liquid is prepared at a temperature of 620～640℃ aluminum alloy semi-solid slurry;

The smaller the α-Al grain size and the higher the sphericity in the aluminum alloy semi-solid slurry, the better the fluidity of the aluminum alloy semi-solid slurry, which is more conducive to semi-solid die-casting. Therefore, obtaining semi-solid slurry of α-Al grain aluminum alloy with fine size and high sphericity is an important condition for semi-solid die-casting. The inventor found through a large number of experimental studies that under the conditions of ultrasonic vibration frequency of 40-50 Hz and vibration time of 20-30 seconds, the semi-solid die-casting aluminum alloy of the present invention can obtain α - Al grain aluminum alloy semi-solid slurry, which has excellent fluidity and is very suitable for semi-solid die-casting;

Step 4: In the mold cavity, the temperature is 100-150 °C, the injection speed is 0.5-1 m/s, the injection specific pressure is 60-80 MPa, the boost pressure is 90-120 MPa and the pressure holding time is 4-6 Under the condition of seconds, the aluminum alloy semi-solid slurry is semi-solid die-casted into aluminum alloy;

The semi-solid slurry is composed of spherical α-Al grains and eutectic liquid phase. This structure is different from the solid-liquid mixed slurry formed by the solidification of traditional dendrites, which determines the process parameters of semi-solid die-casting and traditional liquid die-casting. There are big differences. The inventor has systematically studied the die-casting process of the semi-solid die-casting aluminum alloy of the present invention and found that when the mold cavity temperature is 100-150°C, the injection speed is 0.5-1 m/s, and the injection specific pressure is 60-80 MPa, the increase Under the conditions of pressing pressure of 90-120MPa and holding time of 4-6 seconds, the aluminum alloy semi-solid slurry is semi-solid die-casted into aluminum alloy, which can avoid splashing during the filling process and get involved in gas and inclusions, and meet various requirements. Die-casting requirements for radiator parts with complex shapes and dense structures;

Step 5: Solution treat the semi-solid die-casting aluminum alloy at 520-530°C for 12-14 hours, after water quenching, aging treatment at 175-185°C for 6-8 hours, and obtain semi-solid die-casting high thermal conductivity aluminum after cooling in the furnace alloy.

The microstructure of semi-solid die-casting aluminum alloys is composed of spherical grains and eutectic phases, which is different from the dendritic solidification structure of traditional die-casting aluminum alloys. There are big differences. The inventors systematically studied the solution aging process of the semi-solid die-casting aluminum alloy of the present invention and found that solution treatment at 520-530°C for 12-14 hours, after water quenching, aging treatment at 175-185°C for 6-8 hours, followed by After the furnace is cooled, the semi-solid die-casting aluminum alloy can obtain the desired thermal conductivity and mechanical properties, that is, the thermal conductivity is greater than 160 W/(m K), the tensile strength is greater than 260MPa, and the elongation is greater than 8%. If the solution aging process is not within the above matching range, the semi-solid die-casting aluminum alloy cannot achieve the desired thermal conductivity and mechanical properties.

The technical solution of the present invention will be further described below in conjunction with specific examples and comparative examples, so as to better understand the technical solution of the present invention.

Example 1:

The semi-solid die-casting high thermal conductivity aluminum alloy is composed of the following mass percentages: Si 6.6%, Mg 0.15%, Ti0.03%, Cr 0.05%, Yb 0.01%, Te 0.01%, Be 0.05%, Fe ≤0.15%, and the rest The amount is Al and other unavoidable impurity elements, the individual content of other impurity elements is less than 0.05%, and the total amount is less than 0.15%. The die-casting method of the semi-solid die-casting high thermal conductivity aluminum alloy comprises the following steps:

The first step: according to the composition mass percentage of the aluminum alloy, Al10Ti alloy, Al5Cr1Yb alloy, Al5Te alloy, Al5Be alloy and aluminum ingot with a purity of 99.7%, 99.9% instant silicon and 99.95% magnesium ingot are selected as raw materials for batching;

The second step: heating and melting the aluminum ingot at 750°C, and then adding 6.6% of instant silicon, 0.15% of magnesium ingot, 0.3% of Al10Ti alloy, 1% of Al5Cr1Yb alloy, 0.2% of Al5Te alloy and 1% Al5Be alloy, stirred and melted into aluminum alloy liquid;

Step 3: Use hexachloroethane accounting for 0.5% of the total weight of the raw materials to refine the aluminum alloy liquid for degassing and deslagging, and prepare the aluminum alloy liquid under the condition that the ultrasonic vibration frequency is 40 Hz and the ultrasonic vibration time is 30 seconds. Aluminum alloy semi-solid slurry at a temperature of 640°C;

Step 4: Under the conditions of mold cavity temperature of 100°C, injection speed of 1 m/s, injection specific pressure of 80 MPa, boost pressure of 120 MPa and holding time of 6 seconds, the aluminum alloy semi-solid slurry The material is semi-solid die-cast into aluminum alloy;

Step 5: The semi-solid die-cast aluminum alloy is solution treated at 530°C for 12 hours, after water quenching, it is aged at 175°C for 8 hours, and the semi-solid die-cast aluminum alloy with high thermal conductivity is obtained after cooling in the furnace.

Example 2:

The semi-solid die-casting high thermal conductivity aluminum alloy is composed of the following mass percentages: 7% Si, 0.25% Mg, 0.04% Ti, 0.1% Cr, 0.02% Yb, 0.02% Te, 0.09% Be, Fe ≤0.15%, and the rest The amount is Al and other unavoidable impurity elements, the individual content of other impurity elements is less than 0.05%, and the total amount is less than 0.15%. The die-casting method of the semi-solid die-casting high thermal conductivity aluminum alloy comprises the following steps:

The first step: according to the composition mass percentage of the aluminum alloy, Al10Ti alloy, Al5Cr1Yb alloy, Al5Te alloy, Al5Be alloy and aluminum ingot with a purity of 99.7%, 99.9% instant silicon and 99.95% magnesium ingot are selected as raw materials for batching;

The second step: heating and melting the aluminum ingot at 725°C, and then adding 7% of the total weight of the raw material to the instant silicon, 0.25% of the magnesium ingot, 0.4% of the Al10Ti alloy, 2% of the Al5Cr1Yb alloy, 0.4% of the Al5Te alloy and 1.8% Al5Be alloy, stirred and melted into aluminum alloy liquid;

Step 3: Use hexachloroethane accounting for 0.5% of the total weight of the raw materials to refine the aluminum alloy liquid for degassing and deslagging, and prepare the aluminum alloy liquid under the condition that the ultrasonic vibration frequency is 45 Hz and the ultrasonic vibration time is 25 seconds. Aluminum alloy semi-solid slurry at a temperature of 630°C;

Step 4: Under the conditions of mold cavity temperature of 125°C, injection speed of 0.7 m/s, injection specific pressure of 70 MPa, boost pressure of 100 MPa and holding time of 5 seconds, the aluminum alloy semi-solid slurry The material is semi-solid die-cast into aluminum alloy;

Step 5: The semi-solid die-cast aluminum alloy is solution treated at 525°C for 13 hours, after water quenching, aged at 185°C for 6 hours, and then cooled in a furnace to obtain a semi-solid die-cast aluminum alloy with high thermal conductivity.

Example 3:

The semi-solid die-casting high thermal conductivity aluminum alloy is composed of the following mass percentages: Si 7.4%, Mg 0.2%, Ti0.05%, Cr 0.075%, Yb 0.015%, Te 0.03%, Be 0.1%, Fe ≤0.15%, and the rest The amount is Al and other unavoidable impurity elements, the individual content of other impurity elements is less than 0.05%, and the total amount is less than 0.15%. The die-casting method of the semi-solid die-casting high thermal conductivity aluminum alloy comprises the following steps:

The first step: according to the composition mass percentage of the aluminum alloy, Al10Ti alloy, Al5Cr1Yb alloy, Al5Te alloy, Al5Be alloy and aluminum ingot with a purity of 99.7%, 99.9% instant silicon and 99.95% magnesium ingot are selected as raw materials for batching;

The second step: heating and melting the aluminum ingot at 700°C, and then adding 7.4% of instant silicon, 0.2% of magnesium ingot, 0.5% of Al10Ti alloy, 1.5% of Al5Cr1Yb alloy, 0.6% of Al5Te alloy and 2% Al5Be alloy, stirred and melted into aluminum alloy liquid;

Step 3: Use hexachloroethane accounting for 0.5% of the total weight of raw materials to refine the aluminum alloy liquid to degas and remove slag, and prepare the aluminum alloy liquid under the conditions of ultrasonic vibration frequency of 50 Hz and ultrasonic vibration time of 20 seconds. Aluminum alloy semi-solid slurry at a temperature of 620°C;

Step 4: Under the conditions of mold cavity temperature of 150°C, injection speed of 0.5 m/s, injection specific pressure of 60 MPa, boost pressure of 90 MPa and holding time of 6 seconds, the aluminum alloy semi-solid slurry The material is semi-solid die-cast into aluminum alloy;

Step 5: The semi-solid die-cast aluminum alloy is solution treated at 520°C for 14 hours, after water quenching, aged at 180°C for 7 hours, and then cooled in the furnace to obtain a semi-solid die-cast aluminum alloy with high thermal conductivity.

Comparative example 1:

The semi-solid die-casting high thermal conductivity aluminum alloy is composed of the following mass percentages: Si 7%, Mg 0.25%, Ti0.04%, Te 0.02%, Be 0.09%, Fe ≤0.15%, the balance is Al and unavoidable others Impurity elements, the individual content of other impurity elements is less than 0.05%, and the total content is less than 0.15%. The die-casting method of the semi-solid die-casting high thermal conductivity aluminum alloy comprises the following steps:

The first step: according to the composition mass percentage of the aluminum alloy, Al10Ti alloy, Al5Te alloy, Al5Be alloy and aluminum ingot with a purity of 99.7%, 99.9% instant silicon and 99.95% magnesium ingot are selected as raw materials for batching;

The second step: heating and melting the aluminum ingot at 725°C, and then adding 7% of instant silicon, 0.25% of magnesium ingot, 0.4% of Al10Ti alloy, 0.4% of Al5Te alloy and 1.8% of the total weight of the raw materials Al5Be alloy, Stir and melt into aluminum alloy liquid;

Step 3: Use hexachloroethane accounting for 0.5% of the total weight of the raw materials to refine the aluminum alloy liquid for degassing and slag removal, and prepare the aluminum alloy liquid under the condition that the ultrasonic vibration frequency is 45 Hz and the ultrasonic vibration time is 25 seconds. Aluminum alloy semi-solid slurry at a temperature of 630°C;

Step 4: Under the conditions of mold cavity temperature of 125°C, injection speed of 0.7 m/s, injection specific pressure of 70 MPa, boost pressure of 100 MPa and holding time of 5 seconds, the aluminum alloy semi-solid slurry The material is semi-solid die-cast into aluminum alloy;

Step 5: The semi-solid die-cast aluminum alloy is solution treated at 525°C for 13 hours, after water quenching, aged at 185°C for 6 hours, and then cooled in a furnace to obtain a semi-solid die-cast aluminum alloy with high thermal conductivity.

Comparative example 2:

The semi-solid die-casting high thermal conductivity aluminum alloy is composed of the following mass percentages: Si 7%, Mg 0.25%, Ti0.04%, Cr 0.1%, Yb 0.02%, Be 0.09%, Fe ≤0.15%, the balance is Al and Unavoidable other impurity elements, the individual content of other impurity elements is less than 0.05%, and the total amount is less than 0.15%. The die-casting method of the semi-solid die-casting high thermal conductivity aluminum alloy comprises the following steps:

The first step: according to the composition mass percentage of the aluminum alloy, Al10Ti alloy, Al5Cr1Yb alloy, Al5Be alloy and aluminum ingot with a purity of 99.7%, 99.9% instant silicon and 99.95% magnesium ingot are selected as raw materials for batching;

The second step: heating and melting the aluminum ingot at 725°C, and then adding 7% of instant silicon, 0.25% of magnesium ingot, 0.4% of Al10Ti alloy, 2% of Al5Cr1Yb alloy and 1.8% of the total weight of the raw materials Al5Be alloy, Stir and melt into aluminum alloy liquid;

Step 3: Use hexachloroethane accounting for 0.5% of the total weight of the raw materials to refine the aluminum alloy liquid for degassing and slag removal, and prepare the aluminum alloy liquid under the condition that the ultrasonic vibration frequency is 45 Hz and the ultrasonic vibration time is 25 seconds. Aluminum alloy semi-solid slurry at a temperature of 630°C;

Step 4: Under the conditions of mold cavity temperature of 125°C, injection speed of 0.7 m/s, injection specific pressure of 70 MPa, boost pressure of 100 MPa and holding time of 5 seconds, the aluminum alloy semi-solid slurry The material is semi-solid die-cast into aluminum alloy;

Step 5: The semi-solid die-cast aluminum alloy is solution treated at 525°C for 13 hours, after water quenching, aged at 185°C for 6 hours, and then cooled in a furnace to obtain a semi-solid die-cast aluminum alloy with high thermal conductivity.

Comparative example 3:

The semi-solid die-casting high thermal conductivity aluminum alloy is composed of the following mass percentages: Si 7%, Mg 0.25%, Ti0.04%, Cr 0.1%, Yb 0.02%, Te 0.02%, Fe ≤0.15%, and the balance is Al and Unavoidable other impurity elements, the individual content of other impurity elements is less than 0.05%, and the total amount is less than 0.15%. The die-casting method of the semi-solid die-casting high thermal conductivity aluminum alloy comprises the following steps:

The first step: according to the composition mass percentage of aluminum alloy, Al10Ti alloy, Al5Cr1Yb alloy, Al5Te alloy and aluminum ingot with a purity of 99.7%, 99.9% instant silicon and 99.95% magnesium ingot are selected as raw materials for batching;

The second step: heating and melting the aluminum ingot at 725°C, and then adding 7% of instant silicon, 0.25% of magnesium ingot, 0.4% of Al10Ti alloy, 2% of Al5Cr1Yb alloy and 0.4% of the total weight of the raw materials Al5Te alloy, Stir and melt into aluminum alloy liquid;

Step 3: Use hexachloroethane accounting for 0.5% of the total weight of the raw materials to refine the aluminum alloy liquid for degassing and slag removal, and prepare the aluminum alloy liquid under the condition that the ultrasonic vibration frequency is 45 Hz and the ultrasonic vibration time is 25 seconds. Aluminum alloy semi-solid slurry at a temperature of 630°C;

Step 4: Under the conditions of mold cavity temperature of 125°C, injection speed of 0.7 m/s, injection specific pressure of 70 MPa, boost pressure of 100 MPa and holding time of 5 seconds, the aluminum alloy semi-solid slurry The material is semi-solid die-cast into aluminum alloy;

Step 5: The semi-solid die-cast aluminum alloy is solution treated at 525°C for 13 hours, after water quenching, aged at 185°C for 6 hours, and then cooled in a furnace to obtain a semi-solid die-cast aluminum alloy with high thermal conductivity.

According to the national standard GMN/T16865-2013 of the People's Republic of China, the semi-solid die-casting aluminum alloys of the examples and comparative examples were processed into standard tensile samples, and stretched at room temperature on a DNS500 type electronic tensile testing machine, and the tensile rate was 2 mm/min, the tensile mechanical properties are shown in Table 1. Samples were taken from the semi-solid die-casting aluminum alloys of Examples and Comparative Examples, and the thermal conductivity of the aluminum alloys was measured on a QETRUD thermal conductivity meter. The test results are shown in Table 1. Samples were taken on the semi-solid die-casting aluminum alloys of Examples and Comparative Examples. After the samples were ground, polished and corroded, the average diameter of the α-Al crystal grains was analyzed and measured by the equal-area diameter method under the OLYMPUS metallographic microscope. The equivalent roundness method was used to analyze and measure the average sphericity of α-Al grains, and the test results are shown in Table 1.

It can be seen from Table 1 that the thermal conductivity of the semi-solid die-casting aluminum alloys of Examples 1-3 of the present invention is greater than 160 W/(m K), the tensile strength is greater than 260 MPa, the elongation is greater than 8%, and the α-Al grains The average diameter of the α-Al grains is less than 50 microns, and the average sphericity of the α-Al grains is greater than 0.8. For the semi-solid die-casting high thermal conductivity aluminum alloy of Comparative Example 1, the tensile strength of the semi-solid die-casting high thermal conductivity aluminum alloy is 223.7MPa and the elongation is 4.5% because no Al5Cr1Yb alloy is added to refine and modify the Fe-rich phase. In the semi-solid die-casting high thermal conductivity aluminum alloy of Comparative Example 2, since no Te element was added to refine and modify the eutectic Si phase, the semi-solid die-casting high thermal conductivity aluminum alloy had a tensile strength of 235.6 MPa and an elongation of 3.9%. For the semi-solid die-casting high thermal conductivity aluminum alloy of Comparative Example 3, since no Be element is added, the average grain diameter of the semi-solid die-cast high thermal conductivity aluminum alloy is 45 microns, and the average grain sphericity is 0.67. By comparison, it can be seen that the present invention promotes the spheroidization of α-Al grains by compounding Cr and Yb elements to refine and modify the Fe-rich phase, Te element to refine and modify the eutectic Si phase and Be element, which can significantly provide semi-solid die-casting Strength, plasticity and semi-solid die-casting properties of high thermal conductivity aluminum alloys.

The present invention is described by the embodiment, but does not constitute limitation to the present invention, with reference to the description of the present invention, other changes of the disclosed embodiment, if it is easy for those skilled in the art to imagine, such changes should belong to Within the scope defined by the claims of the present invention.

Claims (1)

1. a kind of pressure casting method of semisolid pressure casting high thermal conductivity aluminium alloy, it is characterised in that the following steps are included:

Step 1: according to the ingredient percent of aluminium alloy, select Al10Ti alloy, Al5Cr1Yb alloy, Al5Te alloy, Aluminium ingot, 99.9% instant silicon and 99.95% magnesium ingot that Al5Be alloy and purity are 99.7% are matched as raw material Material；

Step 2: melt aluminium ingots in 700~750 DEG C of heating, be then added account for raw material total weight be 6.6~7.4% it is instant Silicon, 0.15~0.25% magnesium ingot, 0.3~0.5% Al10Ti alloy, 1~2% Al5Cr1Yb alloy, 0.2~0.6% Al5Te alloy and 1~2% Al5Be alloy, stirring be fused into aluminum alloy melt；

Step 3:, using ultrasonic activation method, being 40 in ultrasonic frequency vibratory after carrying out refining degasification slagging-off to aluminum alloy melt ~50 hertz, the ultrasonic activation time be under the conditions of 20~30 seconds, it is 620~640 DEG C of aluminium that aluminum alloy melt, which is prepared into temperature, Alloy semi-solid slurry；

Step 4: mold cavity temperature is 100~150 DEG C, injection speed is 0.5~1 meter per second, injection ratio pressure be 60~ Under the conditions of 80MPa, boost pressure are 90~120MPa and the dwell time is 4~6 seconds, by aluminium alloy semi-solid slurry semisolid pressure Cast aluminium alloy；

Step 5: by semisolid pressure casting at aluminium alloy 520~530 DEG C solution treatment 12~14 hours, after water quenching, 175 ~185 DEG C ageing treatment 6~8 hours, semisolid pressure casting high thermal conductivity aluminium alloy is obtained after furnace cooling, which leads Hot aluminium alloy is by following mass percent at being grouped as: Si 6.6~7.4%, Mg 0.15~0.25%, Ti 0.03~ 0.05%, Cr 0.05~0.1%, Yb 0.01~0.02%, Te 0.01~0.03%, Be 0.05~0.1%, Fe≤ 0.15%, surplus is Al and inevitable other impurity elements, wherein the mass ratio of Cr and Yb is 5:1, other impurity elements Single content is less than 0.05%, and for total amount less than 0.15%, the thermal coefficient of the semisolid pressure casting high thermal conductivity aluminium alloy is greater than 160W/ (mK), tensile strength is greater than 260MPa, and elongation is greater than 8%.