CN111349821A - Low-silicon low-iron high-fluidity high-thermal-conductivity die-casting aluminum alloy and preparation method thereof - Google Patents

Low-silicon low-iron high-fluidity high-thermal-conductivity die-casting aluminum alloy and preparation method thereof Download PDF

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CN111349821A
CN111349821A CN202010188329.0A CN202010188329A CN111349821A CN 111349821 A CN111349821 A CN 111349821A CN 202010188329 A CN202010188329 A CN 202010188329A CN 111349821 A CN111349821 A CN 111349821A
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die
alloy
low
aluminum alloy
casting
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李远发
李法兵
李国强
宋卓能
陈善荣
刘志翔
赖福宏
朱杰
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Jiafeng Industrial Technology Huizhou Co ltd
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    • CCHEMISTRY; METALLURGY
    • C22METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
    • C22CALLOYS
    • C22C21/00Alloys based on aluminium
    • BPERFORMING OPERATIONS; TRANSPORTING
    • B22CASTING; POWDER METALLURGY
    • B22DCASTING OF METALS; CASTING OF OTHER SUBSTANCES BY THE SAME PROCESSES OR DEVICES
    • B22D17/00Pressure die casting or injection die casting, i.e. casting in which the metal is forced into a mould under high pressure
    • CCHEMISTRY; METALLURGY
    • C22METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
    • C22CALLOYS
    • C22C1/00Making alloys
    • C22C1/02Making alloys by melting
    • C22C1/026Alloys based on aluminium
    • CCHEMISTRY; METALLURGY
    • C22METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
    • C22CALLOYS
    • C22C1/00Making alloys
    • C22C1/02Making alloys by melting
    • C22C1/03Making alloys by melting using master alloys
    • CCHEMISTRY; METALLURGY
    • C22METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
    • C22CALLOYS
    • C22C1/00Making alloys
    • C22C1/06Making alloys with the use of special agents for refining or deoxidising
    • CCHEMISTRY; METALLURGY
    • C22METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
    • C22CALLOYS
    • C22C21/00Alloys based on aluminium
    • C22C21/02Alloys based on aluminium with silicon as the next major constituent

Abstract

The invention discloses a low-silicon low-iron high-fluidity high-heat-conductivity die-casting aluminum alloy and a preparation method thereof. The die-casting aluminum alloy comprises the following components in percentage by mass: 0.05-1.5% of Si, 0.05-0.2% of Fe, 0.05-1.5% of Mn, 0.05-0.7% of Mg, 0.05-5.0% of RE, 0.005-0.3% of Sr, 0.01-0.5% of Ti, 0.001-0.1% of B, and the balance of Al and inevitable impurity elements. The die-casting aluminum alloy ensures high die-casting fluidity of the die-casting aluminum alloy by reducing the contents of Si and Fe and replacing Si with rare earth elements, and prevents die sticking tendency during die-casting by replacing Fe with Mn; in addition, Sr, Ti and B elements are adopted for carrying out rechecking modification treatment, so that the microstructure of the die-casting aluminum alloy is improved, and the heat conductivity coefficient and the strength are improved.

Description

Low-silicon low-iron high-fluidity high-thermal-conductivity die-casting aluminum alloy and preparation method thereof
Technical Field
The invention relates to the technical field of aluminum alloy materials, in particular to a low-silicon low-iron high-fluidity high-heat-conductivity die-casting aluminum alloy and a preparation method thereof.
Background
At present, the fields of 3C products, automotive communication electronics, and the like are under increasing pressure to reduce weight. Meanwhile, some parts often have higher requirements on the heat conductivity of materials (especially heat dissipation devices) so as to ensure and improve the service life and the working stability of products.
The aluminum alloy has good comprehensive performance, and has the advantages of small density, high strength, good electric and thermal conductivity, simple processing and the like, and better meets the requirements of product structure and heat dissipation, thereby being widely applied to the fields of automobiles, electronics, communication and the like. Pure aluminum has a high thermal conductivity at room temperature of about 238W/(m.K), and wrought aluminum alloys such as 6063 also have thermal conductivities as high as 209W/(m.K). Along with the increase of alloy elements, the thermal conductivity of the aluminum alloy is gradually reduced, and the influence of different elements on the thermal conductivity of the alloy is greatly different. This is mainly determined by the free electron thermal conductivity mechanism of the metal, and the thermal conductivity of aluminum alloys is related to the degree of lattice distortion, defects, impurities, phase composition and distribution in the structure.
Compared with forging forming, the die-casting forming has lower production cost, and as a high-speed and high-pressure near-net forming process, the die-casting forming has the characteristics of high production efficiency, high dimensional precision, excellent mechanical property, capability of forming thin-wall deep-cavity castings with complex shapes and clear outlines and the like, and is particularly suitable for integrated design and integrated forming of heat-conducting and heat-dissipating devices.
However, at present, eutectic or near-eutectic aluminum-silicon alloys with the Si content of about 12 percent are the most main die-casting aluminum alloys, the higher Si content ensures better melt fluidity, and the alloy is suitable for die-casting production of thin-wall shell type communication, electronic and traffic field parts, and meanwhile, the aluminum-silicon alloys all have a certain Fe content, so that the continuous production and demoulding are convenient. Si is dissolved in an aluminum matrix in a solid solution mode, so that the heat conductivity coefficient of the aluminum alloy is obviously reduced, the mechanical property of the aluminum alloy is obviously reduced due to the increase of the Fe content, an Al9Fe2Si phase is easily formed in the aluminum alloy by the Si and the Fe, and the heat conductivity coefficient is reduced, so that the heat conductivity coefficient of the eutectic die-casting aluminum-silicon alloy is generally not more than 150W/(m.K).
Therefore, there is a need to develop a high thermal conductive aluminum alloy material having high fluidity characteristics and suitable for die casting.
Disclosure of Invention
The invention aims to provide a high-heat-conduction die-casting aluminum alloy with low silicon, low iron and high fluidity, aiming at the defects or shortcomings in the prior art. The die-casting aluminum alloy ensures high die-casting fluidity of the die-casting aluminum alloy by reducing the contents of Si and Fe and replacing Si with rare earth elements, and prevents die sticking tendency during die-casting by replacing Fe with Mn; in addition, Sr, Ti and B elements are adopted for carrying out rechecking modification treatment, so that the microstructure of the die-casting aluminum alloy is improved, and the heat conductivity coefficient and the strength are improved.
The invention also aims to provide a preparation method for preparing the low-silicon low-iron high-fluidity high-thermal-conductivity die-casting aluminum alloy.
The purpose of the invention is realized by the following technical scheme.
A low-silicon low-iron high-fluidity high-thermal-conductivity die-casting aluminum alloy comprises the following components in percentage by mass:
0.05-1.5% of Si, 0.05-0.2% of Fe, 0.05-1.5% of Mn, 0.05-0.7% of Mg, 0.05-5.0% of RE, 0.005-0.3% of Sr, 0.01-0.5% of Ti, 0.001-0.1% of B, and the balance of Al and inevitable impurity elements.
In a preferred embodiment, the low-silicon low-iron high-fluidity high-thermal-conductivity die-casting aluminum alloy comprises the following components in percentage by mass:
0.05-0.3% of Si, 0.05-0.08% of Fe, 0.05-0.09% of Mn, 0.05-0.1% of Mg, 0.05-1.0% of RE, 0.005-0.009% of Sr, 0.01-0.05% of Ti0.002-0.01% of B, and the balance of Al and inevitable impurity elements.
In a preferred embodiment, the low-silicon low-iron high-fluidity high-thermal-conductivity die-casting aluminum alloy comprises the following components in percentage by mass:
0.45-1.5% of Si, 0.15-0.2% of Fe, 1.0-1.5% of Mn, 0.6-0.7% of Mg, 2.0-5.0% of RE, 0.1-0.3% of Sr, 0.2-0.5% of Ti, 0.04-0.1% of B, and the balance of Al and inevitable impurity elements.
In a preferred embodiment, the RE is one or more of La, Ce and Sm.
In a more preferred embodiment, the RE is La.
In a preferred embodiment, the mass ratio of Si to RE is between 0.3 and 3.5.
In a preferred embodiment, the mass ratio of the Fe to the Mn is between 0.1 and 1.0.
In a preferred embodiment, the ratio of the mass of B to the total mass of Sr and Ti is between 0.13 and 01.5.
The method for preparing the low-silicon low-iron high-fluidity high-thermal-conductivity die-casting aluminum alloy comprises the following steps of:
(1) preparing raw materials: preparing Al ingot, Mg ingot, Al-Ti-B alloy, Al-Sr alloy, Al-RE alloy, Al-Fe alloy, Al-Mn alloy and Al-Si alloy raw materials in a quantitative manner according to the mass percentage;
(2) melting: after the Al ingot is melted, heating to 730-750 ℃, adding the Al-RE alloy, the Al-Fe alloy, the Al-Mn alloy and the Al-Si alloy in batches, melting, and uniformly stirring to obtain a melt I; cooling to 700 ℃, adding the Mg ingot, and melting to obtain a melt II;
(3) refining: heating the melt II to 710-730 ℃, adding a refining agent in batches, and fully and uniformly stirring to obtain a melt III; then introducing argon, and refining for 5-30 min to obtain a melt IV;
(4) modification treatment: heating the melt IV to 710-730 ℃, adding the Al-Ti-B alloy and the Al-Sr alloy, and carrying out composite modification for 0.5-1 h to obtain a melt V; standing for 0.5-1.5 h to obtain a melt VI;
(5) die casting: and cooling the melt VI to 700-710 ℃, fishing out the floating slag on the surface, and casting into ingots to obtain the low-silicon low-iron high-fluidity high-heat-conductivity die-casting aluminum alloy.
In a preferred embodiment, in the step (3), the addition amount of the refining agent is 0.5-2% by mass of the melt II.
In a preferred embodiment, Fe, Mn and Si may also be added in the form of pure metals.
Compared with the prior art, the invention has the following advantages and beneficial effects:
the aluminum alloy of the invention has high thermal conductivity and good mechanical property while containing low Si content and Fe content, wherein the thermal conductivity reaches more than 202W/(m.K), the yield strength reaches more than 135MPa, and the elongation reaches more than 5.6%; the aluminum alloy has low Si and Fe contents, high die casting flowability and high die casting fluidity, and the die casting flow length of the aluminum alloy reaches over 689mm at 700-710 ℃, the injection specific pressure of 30MPa and the filling speed of 2.8 m/s.
Drawings
FIG. 1 is a microstructure diagram of the aluminum alloy of example 4;
FIG. 2 is a microstructure diagram of an aluminum alloy of comparative example 1;
FIG. 3 is a microstructure view of an aluminum alloy of comparative example 2;
FIG. 4 is a microstructure view of an aluminum alloy of comparative example 3;
fig. 5 is a microstructure view of the aluminum alloy of comparative example 4.
Detailed Description
The technical solutions of the present invention are further described in detail with reference to specific examples, which are provided for the purpose of making the disclosure of the present invention more thorough and complete, and the scope of protection and the implementation of the present invention are not limited thereto. Also, unless defined otherwise, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention belongs. The terminology used in the description of the invention herein is for the purpose of describing particular embodiments only and is not intended to be limiting of the invention. In the specific examples, unless otherwise specified, the technical means used are in accordance with the conventional means employed by those skilled in the art of the present invention.
The invention relates to a low-silicon low-iron high-fluidity high-heat-conductivity die-casting aluminum alloy which comprises the following components in percentage by mass:
0.05-1.5% of Si, 0.05-0.2% of Fe, 0.05-1.5% of Mn, 0.05-0.7% of Mg, 0.05-5.0% of RE, 0.005-0.3% of Sr, 0.01-0.5% of Ti, 0.001-0.1% of B, and the balance of Al and inevitable impurity elements.
The die-casting aluminum alloy ensures high fluidity of the die-casting aluminum alloy by reducing the contents of Si and Fe and replacing Si with rare earth elements, and prevents die sticking tendency during die-casting by replacing Fe with Mn; in addition, Sr, Ti and B elements are adopted for carrying out rechecking modification treatment, so that the microstructure of the die-casting aluminum alloy is improved, and the heat conductivity coefficient and the strength are improved. Thus, the aluminum alloy has high thermal conductivity and strength under the condition of low Si and Fe contents, and simultaneously has die-casting performance and high die-casting fluidity.
In a preferred embodiment, the composition comprises the following components in percentage by mass:
0.05-0.3% of Si, 0.05-0.08% of Fe, 0.05-0.09% of Mn, 0.05-0.1% of Mg, 0.05-1.0% of RE, 0.005-0.009% of Sr, 0.01-0.05% of Ti0.002-0.01% of B, and the balance of Al and inevitable impurity elements.
In a preferred embodiment, the composition comprises the following components in percentage by mass:
0.45-1.5% of Si, 0.15-0.2% of Fe, 1.0-1.5% of Mn, 0.6-0.7% of Mg, 2.0-5.0% of RE, 0.1-0.3% of Sr, 0.2-0.5% of Ti, 0.04-0.1% of B, and the balance of Al and inevitable impurity elements.
In a preferred embodiment, the RE is one or more of La, Ce and Sm.
In a preferred embodiment, RE is La.
In a preferred embodiment, the mass ratio of Si to RE is between 0.3 and 3.5.
In a preferred embodiment, the mass ratio of the Fe to the Mn is between 0.1 and 1.0.
In a preferred embodiment, the ratio of the mass of B to the total mass of Sr and Ti is between 0.13 and 01.5.
In the specific embodiment, the raw materials used are as follows:
al ingot: the purity is 99.5%. Mg ingot: the purity is 99.5%.
The alloy types specifically adopted are as follows:
Al-Ti-B alloy: al-5Ti-B alloy. Al-Sr alloy: al-10Sr alloy. Al-La alloy: al-20La alloy. Al-Fe alloy: al-20Fe alloy. Al-Mn alloy: al-10Mn alloy. Al-Si alloy: al-20Si alloy.
The following is a detailed description with reference to specific examples.
Example 1
The low-silicon low-iron high-fluidity high-thermal-conductivity die-casting aluminum alloy comprises the following components in percentage by mass:
0.2% of Si, 0.07% of Fe, 0.07% of Mn, 0.08% of Mg, 0.06% of La, 0.007% of Sr, 0.02% of Ti0.004% of B, and the balance of Al and inevitable impurity elements.
The method for preparing the low-silicon low-iron high-fluidity high-thermal-conductivity die-casting aluminum alloy comprises the following steps of:
(1) preparing raw materials: preparing Al ingot, Mg ingot, Al-Ti-B alloy, Al-Sr alloy, Al-La alloy, Al-Fe alloy, Al-Mn alloy and Al-Si alloy raw materials in a quantitative manner according to the mass percentage;
(2) melting: drying the crucible and each raw material for 24 hours, then using, charging Al ingots along with a furnace, and setting the furnace temperature at 750 ℃;
melting the Al ingot, removing floating slag on the surface, heating to 750 ℃, adding the Al-La alloy, the Al-Fe alloy, the Al-Mn alloy and the Al-Si alloy in batches, slowly immersing the Al-La alloy, the Al-Fe alloy, the Al-Mn alloy and the Al-Si alloy into molten aluminum by using a strainer for bearing, slowly moving the Al-Mn alloy and the Al-Si alloy until the intermediate alloy is completely melted, and uniformly stirring after melting to obtain a melt I; cooling to 700 ℃, adding the Mg ingot, melting, and fishing out floating slag on the surface to obtain a melt II;
(3) refining: heating the melt II to 710 ℃, adding a refining agent in batches (the addition amount of the refining agent is 1.0 percent in mass percent of the melt II), and fully and uniformly stirring to obtain a melt III;
then introducing argon, fully preheating an air pipe before degassing, brushing a coating, extending the air pipe into the middle lower part of the melt, slowly moving the air pipe to enable all parts of the melt to be uniform, preferably blowing small bubbles out of the gas flow on the liquid level, and refining for 5-30 min to obtain a melt IV;
(4) modification treatment: removing floating slag and a refining agent on the surface, heating the melt IV to 730 ℃, adding the Al-Ti-B alloy and the Al-Sr alloy, and carrying out composite modification treatment for 1h to obtain a melt V;
standing for 1.5h to obtain a melt VI;
(5) die casting: and (3) cooling the melt VI to 710 ℃, fishing out the surface scum, and then carrying out die-casting under the injection specific pressure of 30MPa and the filling speed of 2.8m/s, wherein the temperature of a die-casting die is 300 ℃, so as to obtain the die-casting formed low-silicon low-iron high-fluidity high-heat-conductivity die-casting aluminum alloy.
Example 2
The low-silicon low-iron high-fluidity high-thermal-conductivity die-casting aluminum alloy comprises the following components in percentage by mass:
0.06% of Si, 0.05% of Fe, 0.05% of Mn, 0.05% of Mg, 0.1% of La, 0.005% of Sr, 0.01% of Ti0.002% of B, and the balance of Al and inevitable impurity elements.
The method for preparing the low-silicon low-iron high-fluidity high-thermal-conductivity die-casting aluminum alloy comprises the following steps of:
(1) preparing raw materials: preparing Al ingot, Mg ingot, Al-Ti-B alloy, Al-Sr alloy, Al-La alloy, Al-Fe alloy, Al-Mn alloy and Al-Si alloy raw materials in a quantitative manner according to the mass percentage;
(2) melting: drying the crucible and each raw material for 24 hours, then using, charging Al ingots along with a furnace, and setting the furnace temperature at 750 ℃;
melting the Al ingot, removing floating slag on the surface, heating to 750 ℃, adding the Al-La alloy, the Al-Fe alloy, the Al-Mn alloy and the Al-Si alloy in batches, slowly immersing the Al-La alloy, the Al-Fe alloy, the Al-Mn alloy and the Al-Si alloy into molten aluminum by using a strainer for bearing, slowly moving the Al-Mn alloy and the Al-Si alloy until the intermediate alloy is completely melted, and uniformly stirring after melting to obtain a melt I; cooling to 700 ℃, adding the Mg ingot, melting, and fishing out floating slag on the surface to obtain a melt II;
(3) refining: heating the melt II to 720 ℃, adding a refining agent in batches (the addition amount of the refining agent is 1.5 percent in mass percent of the melt II), and fully and uniformly stirring to obtain a melt III;
then introducing argon, fully preheating an air pipe before degassing, brushing a coating, extending the air pipe into the middle lower part of the melt, slowly moving the air pipe to enable all parts of the melt to be uniform, preferably blowing small bubbles out of the gas flow on the liquid level, and refining for 5-30 min to obtain a melt IV;
(4) modification treatment: removing floating slag and a refining agent on the surface, heating the melt IV to 730 ℃, adding the Al-Ti-B alloy and the Al-Sr alloy, and carrying out composite modification treatment for 1h to obtain a melt V;
then standing for 1.0h to obtain a melt VI;
(5) die casting: and (3) cooling the melt VI to 700 ℃, fishing out the surface scum, and then carrying out die-casting under the injection specific pressure of 30MPa and the filling speed of 2.8m/s, wherein the temperature of a die-casting die is 300 ℃, so as to obtain the die-casting formed low-silicon low-iron high-fluidity high-heat-conductivity die-casting aluminum alloy.
Example 3
The low-silicon low-iron high-fluidity high-thermal-conductivity die-casting aluminum alloy comprises the following components in percentage by mass:
1.0% of Si, 0.15% of Fe, 1.2% of Mn, 0.6% of Mg, 2.0% of La, 0.1% of Sr, 0.2% of Ti, 0.04% of B, and the balance of Al and inevitable impurity elements.
The method for preparing the low-silicon low-iron high-fluidity high-thermal-conductivity die-casting aluminum alloy comprises the following steps of:
(1) preparing raw materials: preparing Al ingot, Mg ingot, Al-Ti-B alloy, Al-Sr alloy, Al-La alloy, Al-Fe alloy, Al-Mn alloy and Al-Si alloy raw materials in a quantitative manner according to the mass percentage;
(2) melting: drying the crucible and each raw material for 24 hours, then using, charging Al ingots along with a furnace, and setting the furnace temperature at 750 ℃;
melting the Al ingot, removing floating slag on the surface, heating to 730 ℃, adding the Al-La alloy, the Al-Fe alloy, the Al-Mn alloy and the Al-Si alloy in batches, slowly immersing the Al ingot in the middle of molten aluminum by using a colander for slowly moving until the intermediate alloy is completely melted, and uniformly stirring after melting to obtain a melt I; cooling to 700 ℃, adding the Mg ingot, melting, and fishing out floating slag on the surface to obtain a melt II;
(3) refining: heating the melt II to 720 ℃, adding a refining agent in batches (the addition amount of the refining agent is 2 percent by mass of the melt II), and fully and uniformly stirring to obtain a melt III;
then introducing argon, fully preheating an air pipe before degassing, brushing a coating, extending the air pipe into the middle lower part of the melt, slowly moving the air pipe to enable all parts of the melt to be uniform, preferably blowing small bubbles out of the gas flow on the liquid level, and refining for 5-30 min to obtain a melt IV;
(4) modification treatment: removing floating slag and a refining agent on the surface, keeping the temperature of the melt IV at 720 ℃, adding the Al-Ti-B alloy and the Al-Sr alloy, and carrying out composite modification treatment for 0.5h to obtain a melt V;
then standing for 1.0h to obtain a melt VI;
(5) die casting: and (3) cooling the melt VI to 700 ℃, fishing out the surface scum, and then carrying out die-casting under the injection specific pressure of 30MPa and the filling speed of 2.8m/s, wherein the temperature of a die-casting die is 300 ℃, so as to obtain the die-casting formed low-silicon low-iron high-fluidity high-heat-conductivity die-casting aluminum alloy.
Example 4
The low-silicon low-iron high-fluidity high-thermal-conductivity die-casting aluminum alloy comprises the following components in percentage by mass:
1.5% of Si, 0.19% of Fe, 1.5% of Mn, 0.6% of Mg, 4.0% of La, 0.2% of Sr, 0.4% of Ti, 0.08% of B, and the balance of Al and inevitable impurity elements.
The method for preparing the low-silicon low-iron high-fluidity high-thermal-conductivity die-casting aluminum alloy comprises the following steps of:
(1) preparing raw materials: preparing Al ingot, Mg ingot, Al-Ti-B alloy, Al-Sr alloy, Al-La alloy, Al-Fe alloy, Al-Mn alloy and Al-Si alloy raw materials in a quantitative manner according to the mass percentage;
(2) melting: drying the crucible and each raw material for 24 hours, then using, charging Al ingots along with a furnace, and setting the furnace temperature at 750 ℃;
melting the Al ingot, removing floating slag on the surface, heating to 750 ℃, adding the Al-La alloy, the Al-Fe alloy, the Al-Mn alloy and the Al-Si alloy in batches, slowly immersing the Al-La alloy, the Al-Fe alloy, the Al-Mn alloy and the Al-Si alloy into molten aluminum by using a strainer for bearing, slowly moving the Al-Mn alloy and the Al-Si alloy until the intermediate alloy is completely melted, and uniformly stirring after melting to obtain a melt I; cooling to 700 ℃, adding the Mg ingot, melting, and fishing out floating slag on the surface to obtain a melt II;
(3) refining: heating the melt II to 730 ℃, adding a refining agent in batches (the addition amount of the refining agent is 0.5 percent in mass percent of the melt II), and fully and uniformly stirring to obtain a melt III;
then introducing argon, fully preheating an air pipe before degassing, brushing a coating, extending the air pipe into the middle lower part of the melt, slowly moving the air pipe to enable all parts of the melt to be uniform, preferably blowing small bubbles out of the gas flow on the liquid level, and refining for 5-30 min to obtain a melt IV;
(4) modification treatment: removing floating slag and a refining agent on the surface, keeping the temperature of the melt IV at 730 ℃, adding the Al-Ti-B alloy and the Al-Sr alloy, and performing composite modification for 1h to obtain a melt V;
then standing for 0.5h to obtain a melt VI;
(5) die casting: and (3) cooling the melt VI to 710 ℃, fishing out the surface scum, and then carrying out die-casting under the injection specific pressure of 30MPa and the filling speed of 2.8m/s, wherein the temperature of a die-casting die is 300 ℃, so as to obtain the die-casting formed low-silicon low-iron high-fluidity high-heat-conductivity die-casting aluminum alloy.
Comparative example 1
The die-casting aluminum alloy of the comparative example comprises the following components in percentage by mass:
2.0% of Si, 0.6% of Fe, 0.05% of Mn, 0.9% of Mg, 0.1% of La, 0.005% of Sr, 0.01% of Ti, 0.002% of B, and the balance of Al and inevitable impurity elements.
A die-cast aluminum alloy die-cast according to this comparative example was prepared by the method of example 2.
Comparative example 2
The die-casting aluminum alloy of the comparative example comprises the following components in percentage by mass:
3.06% of Si, 0.8% of Fe, 0.05% of Mn, 1.2% of Mg, 0.1% of La, 0.005% of Sr, 0.01% of Ti, 0.002% of B, and the balance of Al and inevitable impurity elements.
A die-cast aluminum alloy die-cast according to this comparative example was prepared by the method of example 2.
Comparative example 3
The die-casting aluminum alloy of the comparative example comprises the following components in percentage by mass:
8.2% of Si, 1.0% of Fe, 0.05% of Mn, 1.5% of Mg, 0.1% of La, 0.005% of Sr, 0.01% of Ti, 0.002% of B, and the balance of Al and inevitable impurity elements.
A die-cast aluminum alloy die-cast according to this comparative example was prepared by the method of example 2.
Comparative example 4
The die-cast aluminum alloy of this comparative example was the ADC12 aluminum alloy.
After melting the ADC12 aluminum alloy of this comparative example, the temperature was lowered to 700 ℃, and a die casting test was performed at a pressure injection specific pressure of 30MPa and a filling speed of 2.8m/s, wherein the temperature of the die casting mold was 300 ℃.
Performance testing
1. Microstructure observation
The microstructure of the die-cast aluminum alloys of examples 1 to 4 and comparative examples 1 to 3 is observed by an electron microscope, and corresponding electron microscope scanning images are shown in fig. 1 to 5, wherein fig. 1 is the microstructure electron microscope scanning image of the die-cast aluminum alloy of example 4, and the microstructure observation results of examples 1 to 3 are shown in fig. 1, and it can be seen from fig. 1 that the microstructure obtained after die-casting the aluminum alloys of examples 1 to 4 has a precipitation strengthening phase of 2 to 4 μm and an ultrafine discontinuous lamellar network skeleton structure except for α -Al matrix, and the special microstructure not only ensures the ultrahigh thermal conductivity of the aluminum alloy, but also can maintain the better fluidity and strength characteristics of the aluminum alloy, and has an extremely important practical value.
Fig. 2 is an electron microscope scanning image of the microstructure of the die-cast aluminum alloy of comparative example 1, and it can be seen from fig. 2 that the die-cast aluminum alloy of comparative example 1 has a significant effect of refining the grains of the composite modifier, and the characteristic microstructure can satisfy the basic fluidity and the better strength characteristic of the aluminum alloy, but makes the aluminum alloy have a lower thermal conductivity and a lower practicability.
Fig. 3 is a scanning electron microscope image of the microstructure of the die-cast aluminum alloy of comparative example 2, and it can be seen from fig. 3 that the grain refining effect of the composite modifier in the die-cast aluminum alloy of comparative example 2 is significant, and the characteristic microstructure can satisfy the better fluidity and strength characteristics of the aluminum alloy, but makes the aluminum alloy have lower thermal conductivity and low practicability.
Fig. 4 is a scanning electron microscope image of the microstructure of the die-cast aluminum alloy of the comparative example 3, and it can be seen from fig. 4 that the composite modifier in the die-cast aluminum alloy of the comparative example 3 has a significant grain refinement effect, and the flaky silicon phase is finely fragmented, and the characteristic microstructure can satisfy the better fluidity and strength characteristics of the aluminum alloy, but makes the aluminum alloy have lower thermal conductivity and low practicability.
Fig. 5 is an electron microscope scanning image of the microstructure of the die-cast aluminum alloy of comparative example 4, and fig. 5 shows that the die-cast aluminum alloy of comparative example 4 has no morphological feature of precipitation of the flaky eutectic silicon phase with the deterioration effect, no precipitation of the strengthening phase and no existence of the ultrafine lamellar discontinuous network skeleton structure, and can satisfy the good fluidity and strength characteristics of the aluminum alloy, but has little contribution to the thermal conductivity of the aluminum alloy and low practicability.
From the above observation, the aluminum alloy of the embodiments 1 to 4 has the microstructure characteristics significantly different from those of the conventional aluminum alloy and the high-silicon high-iron alloy under the compatibility of the low-silicon low-iron alloy, and the microstructure characteristics show that the aluminum alloy of the embodiments 1 to 4 has the ultrahigh heat conductivity while maintaining the good fluidity and strength characteristics. The aluminum alloy of the invention has high heat conductivity coefficient, good die casting performance and good mechanical property while containing low Si content and Fe content.
2. Die casting flowability test
The flow length of the die casting was tested and the test results are shown in table 1.
TABLE 1 die casting fluidity test results of die casting aluminum alloys of examples 1 to 4 and comparative examples 1 to 3
The test results in table 1 show that the die casting fluidity of the die casting aluminum alloys of examples 1 to 4 is generally better than that of comparative examples 1 to 4, and the die casting fluidity of examples 3 and 4 can reach 782mm and 809mm, which indicates that the die casting aluminum alloy of the invention has die casting performance under low Si and Fe contents and high die casting fluidity. Moreover, as can be seen from comparison between examples 1 to 4 and comparative examples 1 to 3, the die-casting aluminum alloy of the present invention has a reduced Si content, and the rare earth element is used in place of the Si element, so that the die-casting fluidity of the aluminum alloy can be effectively ensured during die-casting.
3. Mechanical property test of alloy
Mechanical property tests were performed on the die-cast aluminum alloys of examples 1 to 4 and comparative examples 1 to 3, and the test results are shown in table 2.
TABLE 2 mechanical property test results of the die-cast aluminum alloys of examples 1 to 4 and comparative examples 1 to 3
The test results in table 2 show that examples 1 to 4 still maintain good mechanical properties, which indicates that the die-casting aluminum alloy of the present invention still maintains excellent mechanical properties through compatibility of the components under low Si and Fe contents, and has high practical application value.
4. Thermal conductivity test
The die-cast aluminum alloys of examples 1 to 4 and comparative examples 1 to 3 were subjected to a thermal conductivity test (thermal diffusivity and thermal conductivity were measured by flash method in reference to the standard GB/T22588-2008, 25 ℃), and the test results are shown in table 3.
TABLE 3 Heat conductivity coefficient test results of the die-cast aluminum alloys of examples 1 to 4 and comparative examples 1 to 3
The test results in table 3 show that the heat conductivity of the die-casting aluminum alloys of examples 1 to 4 is much higher than that of comparative examples 1 to 4, and the heat conductivity of examples 1 to 4 reaches 202W/(m.k) or more, and has an ultrahigh heat conductivity, which indicates that the die-casting aluminum alloy of the present invention has good heat conductivity at low Si and Fe contents.
5. Die-casting die-bonding observation
The die-cast aluminum alloys of examples 1 to 4 and comparative examples 1 to 3 were observed for sticking when the samples were taken out after die-casting was completed and the die-casting was opened, and the results of the observation are shown in table 4.
TABLE 4 die-casting sticking observation results of die-casting aluminum alloys of examples 1 to 4 and comparative examples 1 to 3
As can be seen from the test results in Table 4, the die-casting aluminum alloys of examples 1 to 4 did not suffer from die sticking during die-casting and demolding, and the demolding specimens were intact. Moreover, as can be seen from comparison between examples 1 to 4 and comparative examples 1 to 3, the die-casting aluminum alloy of the present invention has a reduced Fe content, and the Mn element is used instead of the Fe element, so that the die-casting aluminum alloy still has a good die-sticking prevention effect during die-casting, and has good die-casting performance.
The test results show that the die-casting aluminum alloy has low Si content and Fe content, has die-casting performance and high die-casting fluidity, and is suitable for die-casting molding; and the die-casting aluminum alloy still has high heat conductivity coefficient and good mechanical property, which shows that the die-casting aluminum alloy has good practical application value.
It will be evident to those skilled in the art that the invention is not limited to the details of the foregoing illustrative embodiments, such as the incorporation of La, Ti, Sr, Fe, Mn, Si, B, etc. in the form of alloys such as Al-La alloys, Al-Ti-B alloys, Al-Sr alloys, Al-Fe alloys, Al-Mn alloys, Al-Si alloys, etc., in alternative embodiments, in the form of other possible alloys or materials, and that the present invention may be embodied in other specific forms without departing from the spirit or essential characteristics thereof. The present embodiments are therefore to be considered in all respects as illustrative and not restrictive, the scope of the invention being indicated by the appended claims rather than by the foregoing description, and all changes which come within the meaning and range of equivalency of the claims are therefore intended to be embraced therein.
Furthermore, it should be understood that although the present description refers to embodiments, not every embodiment may include only a single embodiment, and such description is for clarity only, and those skilled in the art should make the description as a whole, and the embodiments may be appropriately combined, changed, replaced, or modified to form other embodiments understood by those skilled in the art.

Claims (10)

1. The die-casting aluminum alloy with low silicon, low iron and high fluidity and high heat conductivity is characterized by comprising the following components in percentage by mass:
0.05-1.5% of Si, 0.05-0.2% of Fe, 0.05-1.5% of Mn, 0.05-0.7% of Mg, 0.05-5.0% of RE, 0.005-0.3% of Sr, 0.01-0.5% of Ti, 0.001-0.1% of B, and the balance of Al and inevitable impurity elements.
2. The die-casting aluminum alloy with low silicon, low iron and high fluidity and high thermal conductivity as claimed in claim 1, which comprises the following components in percentage by mass:
0.05-0.3% of Si, 0.05-0.08% of Fe, 0.05-0.09% of Mn, 0.05-0.1% of Mg, 0.05-1.0% of RE, 0.005-0.009% of Sr0.01-0.05% of Ti, 0.002-0.01% of B, and the balance of Al and inevitable impurity elements.
3. The die-casting aluminum alloy with low silicon, low iron and high fluidity and high thermal conductivity as claimed in claim 1, which comprises the following components in percentage by mass:
0.45-1.5% of Si, 0.15-0.2% of Fe, 1.0-1.5% of Mn, 0.6-0.7% of Mg, 2.0-5.0% of RE, 0.1-0.3% of Sr, 0.2-0.5% of Ti, 0.04-0.1% of B, and the balance of Al and inevitable impurity elements.
4. The die-casting aluminum alloy with low silicon, low iron and high fluidity and high thermal conductivity as claimed in any one of claims 1 to 3, wherein RE is more than one of La, Ce and Sm.
5. The die-casting aluminum alloy with low silicon, low iron and high fluidity and high thermal conductivity as claimed in any one of claims 1 to 3, wherein RE is La.
6. A low-Si low-Fe high-fluidity high-thermal-conductivity die-cast aluminum alloy according to any one of claims 1 to 3, wherein the mass ratio of Si to RE is 0.3 to 3.5.
7. A low-silicon low-iron high-fluidity high-thermal-conductivity die-cast aluminum alloy according to any one of claims 1 to 3, wherein the mass ratio of Fe to Mn is between 0.1 and 1.0.
8. A die-cast aluminum alloy with low silicon, low iron and high fluidity and high thermal conductivity as claimed in any one of claims 1 to 3, wherein the ratio of the mass of B to the total mass of Sr and Ti is between 0.13 and 01.5.
9. The method for preparing the low-silicon low-iron high-fluidity high-thermal-conductivity die-casting aluminum alloy according to any one of claims 1 to 8, which is characterized by comprising the following steps of:
(1) preparing raw materials: preparing Al ingot, Mg ingot, Al-Ti-B alloy, Al-Sr alloy, Al-RE alloy, Al-Fe alloy, Al-Mn alloy and Al-Si alloy raw materials in a quantitative manner according to the mass percentage;
(2) melting: after the Al ingot is melted, heating to 730-750 ℃, adding the Al-RE alloy, the Al-Fe alloy, the Al-Mn alloy and the Al-Si alloy in batches, melting, and uniformly stirring to obtain a melt I; cooling to 700 ℃, adding the Mg ingot, and melting to obtain a melt II;
(3) refining: heating the melt II to 710-730 ℃, adding a refining agent in batches, and fully and uniformly stirring to obtain a melt III; then introducing argon, and refining for 5-30 min to obtain a melt IV;
(4) modification treatment: heating the melt IV to 710-730 ℃, adding the Al-Ti-B alloy and the Al-Sr alloy, and carrying out composite modification for 0.5-1 h to obtain a melt V; standing for 0.5-1.5 h to obtain a melt VI;
(5) pouring: and cooling the melt VI to 700-710 ℃, fishing out the floating slag on the surface, and casting into ingots to obtain the low-silicon low-iron high-fluidity high-heat-conductivity die-casting aluminum alloy.
10. The method according to claim 9, wherein in the step (3), the refining agent is added in an amount of 0.5 to 2% by mass based on the mass of the melt II.
CN202010188329.0A 2020-03-17 2020-03-17 Low-silicon low-iron high-fluidity high-thermal-conductivity die-casting aluminum alloy and preparation method thereof Pending CN111349821A (en)

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CN111690844A (en) * 2020-07-08 2020-09-22 沈阳航空航天大学 Eutectic Al-Fe-Mn-Si-Mg die casting alloy and preparation method and application thereof
CN111690843A (en) * 2020-07-08 2020-09-22 沈阳航空航天大学 High Fe content Al-Fe-Mn alloy for kitchen ware and its making method
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CN111690844A (en) * 2020-07-08 2020-09-22 沈阳航空航天大学 Eutectic Al-Fe-Mn-Si-Mg die casting alloy and preparation method and application thereof
CN111690843A (en) * 2020-07-08 2020-09-22 沈阳航空航天大学 High Fe content Al-Fe-Mn alloy for kitchen ware and its making method
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