CN114959370A - High-strength high-toughness high-heat-conductivity aluminum alloy suitable for die-casting molding and die-casting preparation method thereof - Google Patents

Abstract

The invention provides a high-strength, high-toughness and high-heat-conductivity aluminum alloy suitable for die-casting molding and a die-casting preparation method thereof, belonging to the technical field of aluminum alloy manufacturing. The invention provides a high-strength, high-toughness and high-heat-conductivity aluminum alloy suitable for die-casting molding, which comprises the following components in percentage by mass: 5.0-7.0% of Ni, 0.3-3.0% of microalloy elements and the balance of Al; the microalloying element comprises one or more of Ce, Si and Cu. The results of the examples show that the thermal conductivity of the high-strength high-toughness high-thermal-conductivity aluminum alloy suitable for die-casting forming can reach 215W/(m.K), the tensile strength and the elongation can reach 259MPa and 25.5%, and the viscosity coefficient is 10s ^‑1 The shear rate can be reduced to 1.11 pas.

Description

A high-strength, tough, high-thermal-conductivity aluminum alloy suitable for die-casting and a die-casting preparation method thereof

technical field

The invention relates to the technical field of aluminum alloy manufacturing, in particular to a high-strength, toughness, and high-thermal-conductivity aluminum alloy suitable for die-casting and a die-casting preparation method thereof.

Background technique

With the development of electronic communication terminals, base stations, new energy vehicle battery modules, etc. towards high power, miniaturization and light weight, the power density of miniaturized electronic equipment is high, and the implementation of effective thermal management is the key to improving its work efficiency and service life. Assure. Due to the pursuit of lightweight thermal management products, high-performance aluminum alloys are one of the most promising thermal management materials, which can meet the requirements of thermal management materials for thermal conductivity and mechanical properties. At present, although commercial deformed aluminum alloys can be processed into thin-walled and complex structural parts by using the "aluminum extrusion/forging + CNC" process to meet the needs of consumer electronics and communication base stations, the production efficiency is low, and the processing process of aluminum The amount of waste discharged is large, and it is difficult to meet the needs of large-scale production capacity. The aluminum alloy structural parts are prepared based on the pressure casting (die casting) method, which has high production efficiency, low production cost, saves materials and post-processing procedures, and can meet the needs of mass production. However, commercial deformed aluminum alloys with both high thermal conductivity and high strength and toughness have small latent heat of solidification and high melt viscosity, making it difficult to adapt to the die-casting process. Materials have become the focus of the industry. How to design and develop an aluminum alloy with good melt fluidity, high thermal conductivity and high strength and toughness has become the key to the preparation of thin-walled and complex-structured aluminum alloy parts by die casting.

Chinese invention patent application CN113106300A discloses a heat-free high thermal conductivity aluminum alloy, a preparation method thereof, and a radiator. The patent controls the Cu content to be 0.5-2.0%, Fe to be 1.0-3.0%, Mg to be 0-0.1%, B to be 0.01-0.1%, RE to be 0.01-0.2%, Ti to be 0.001-0.01%, and the rest to be Al and Inevitable impurities, an aluminum alloy with high thermal conductivity and no heat treatment is obtained through composition optimization, but its mechanical properties are relatively low. The requirements for the mechanical properties of the materials in the assembly and service stages; in addition, the Al-Fe alloys have coarse acicular Al ₃ Fe phases, which are not only prone to hot cracking, but also difficult to meet the requirements of integrated die-casting, and are also extremely unfavorable to the mechanical properties of the alloys. .

Chinese invention patent application CN113265567A discloses a high thermal conductivity, high strength and toughness cast aluminum alloy and a preparation method thereof. The technology controls the composition of the alloy: Si content is 7.0-9.0%, Fe is 0.45-0.85%, Cu is 0.08-0.5%, Mg is 0.3-0.8%, and the rest are Al and inevitable impurities. A high thermal conductivity, high strength and toughness cast aluminum alloy is obtained by adjusting the alloy composition. Functional structural components in the field of computers, etc. However, the thermal conductivity of this alloy system is relatively low, and it is difficult to meet the thermal conductivity requirements of high power density thermal management devices.

Chinese invention patent application CN112962005A discloses a method for preparing a high-strength, tough, and high-thermal-conductivity aluminum alloy suitable for die-casting. This technology plans the content of the alloy as follows: Si content is 0.3-1.2%, Fe is 0-0.3%, Cu is 0-1.0%, Mn is 0-1.0%, Mg is 0.3-1.3%, Cr is 0-0.3% %, Ni is 0-0.2%, Zn is 0-1.0%, Ti is 0-0.1%, and the rest is Al and inevitable impurities. By performing homogenization heat treatment, extrusion deformation, solution quenching, and short-time artificial aging treatment on the alloy, an aluminum alloy that takes into account material strength, elongation and thermal conductivity is finally obtained. Through the scientific combination of deformation system and heat treatment process, the balance of material strength and thermal conductivity is achieved, and finally high-performance aluminum alloy products are obtained. However, when an aluminum alloy is prepared by die-casting with this composition system, the alloy melt has poor fluidity, that is, the aluminum alloy melt has a high viscosity coefficient during the die-casting process, and there are still the following problems: (1) After heat treatment, there are bulges, etc. The problem of poor appearance makes it difficult to meet the product appearance requirements; (2) Elements such as Si, Cu, Mg, Cr, and Mn have high solid solubility in aluminum. It is difficult to meet the high thermal conductivity requirements for aluminum alloys in the industry. Therefore, this technology cannot meet the requirements of die-casting integrated molding.

Some of the above-mentioned patented technologies all involve high-strength and high-thermal-conductivity aluminum alloys. These alloys are difficult to achieve the mutual balance of thermal conductivity, mechanical properties and die-casting flow properties at the same time, so they cannot meet the current requirements for electronic devices and new energy vehicles. The thermal conductivity, toughness, and flow formability requirements of thermal management materials limit the industrial application of these alloys in high-power electronic components.

Therefore, how to provide a die-casting aluminum alloy that can simultaneously achieve a balance between thermal conductivity, mechanical properties and die-casting fluidity has become an urgent technical problem to be solved in the art.

SUMMARY OF THE INVENTION

The purpose of the present invention is to provide a high-strength, toughness, and high-thermal-conductivity aluminum alloy suitable for die-casting and a die-casting preparation method thereof. It has the characteristics of excellent thermal conductivity, and the melt at high temperature has good flow properties.

In order to achieve the above-mentioned purpose of the invention, the present invention provides the following technical solutions:

The invention provides a high-strength, toughness, and high-thermal-conductivity aluminum alloy suitable for die-casting, which, in terms of mass percentage, comprises: 5.0-7.0% of Ni, 0.3-3.0% of microalloying elements and the balance of Al;

The microalloying elements include one or more of Ce, Si and Cu.

Preferably, the mass percentages of Ce, Si and Cu are independently 0.3-1.0%.

The present invention provides a method for preparing a high-strength, high-toughness, and high-thermal-conductivity aluminum alloy suitable for die-casting according to the above technical solution, comprising the following steps:

(1) melting metal Al and Al-Ni master alloy to obtain Al-Ni alloy melt;

(2) adding a master alloy of microalloying elements to the Al-Ni alloy melt obtained in the step (1), and performing microalloy strengthening treatment to obtain a strengthened aluminum alloy melt;

(3) refining and removing slag from the strengthened aluminum alloy melt obtained in the step (2) to obtain a refining aluminum alloy melt;

(4) Performing high pressure casting on the refined aluminum alloy melt obtained in the step (3) to obtain an aluminum alloy with high strength, toughness and high thermal conductivity suitable for die casting.

Preferably, the Al-Ni master alloy in the step (1) is an Al-10Ni master alloy.

Preferably, the melting temperature in the step (1) is 690-720°C.

Preferably, the master alloy of microalloying elements in the step (2) includes one or more of Al-20Ce master alloy, Al-50Cu master alloy and Al-20Si master alloy.

Preferably, the temperature of the microalloy strengthening treatment in the step (2) is 690-720°C.

Preferably, the refining and slag removing method in the step (3) is to sequentially add a refining agent and a slag removing agent to the strengthened aluminum alloy melt.

Preferably, the high-pressure casting method in the step (4) is as follows: firstly, the refined aluminum alloy melt is pressed into the die-casting melt filling chamber, and then pressed into the mold.

Preferably, the injection rate of the injection into the die-casting melt filling chamber is 30-80 cm/s, and the injection rate of the injection into the mold is 200-600 cm/s.

The present invention provides an aluminum alloy with high strength, toughness and high thermal conductivity suitable for die-casting. In terms of mass percentage, it includes: 5.0-7.0% Ni, 0.3-3.0% microalloying elements and the balance of Al; the microalloying The elements include one or more of Ce, Si and Cu. In the high-strength, toughness, and high-thermal-conductivity aluminum alloy suitable for die-casting provided by the present invention, the metallurgical reaction between Ni element and Al element forms an Al ₃ Ni phase with excellent strengthening effect, which effectively improves the mechanical properties of the alloy. Meanwhile, the Al-Ni system has Relatively low eutectic temperature and relatively large latent heat of crystallization are conducive to the flow filling performance of the alloy, which can meet the mass production of integrated die-casting; Ce element can inhibit the growth of the second phase in the aluminum alloy and achieve refinement The effect of microstructure, thereby significantly improving the mechanical properties and thermal conductivity of the alloy, and the low solid solubility of Ce element in aluminum, the effect on the flow properties of aluminum alloy is relatively small; Si element has a good strengthening effect in aluminum alloy. , which can significantly improve the mechanical properties and flow properties of aluminum alloys. By controlling the addition of Si element, the influence on the thermal conductivity of aluminum alloys can be reduced, so that the mutual balance between thermal conductivity and mechanical properties of alloys can be achieved; Cu elements can form Al with Al. ₂ Cu precipitation phase plays a significant role in dispersion strengthening, and Cu element has a certain solid solubility in the aluminum matrix, which can play a role in solid solution strengthening. The scattering effect caused by the movement of free electrons leads to the deterioration of the thermal conductivity of the alloy, so that it can meet the dual requirements of electronic components for thermal conductivity and mechanical properties of thermal management materials; one or more of Ce, Cu and Si elements are used for aluminum alloys. Multi-element microalloy strengthening treatment is carried out to control the microstructure, morphology and distribution of the eutectic alloy. On the premise of ensuring the thermal conductivity of the alloy, the mechanical properties of the Al-Ni alloy are optimized and the melt viscosity of the aluminum alloy is reduced. The effect of relatively coarse grain structure (α-Al+Al ₃ Ni) on the alloy elongation. The results of the examples show that the thermal conductivity of the high-strength, toughness, and high-thermal-conductivity aluminum alloys suitable for die-casting provided by the present invention can reach 215W/(m·K), the tensile strength and elongation are as high as 259MPa and 25.5%, and the viscosity coefficient is 10s ^-1 shear rate can be reduced to 1.11Pa·s.

Description of drawings

Fig. 1 is the optical microstructure of the die-cast A1-5Ni-0.5Ce-1.0Si-1.0Cu alloy prepared in Example 6 of the present invention;

2 is the optical microstructure of the die-cast A356 alloy prepared in Comparative Example 1 of the present invention;

3 is the optical microstructure of the die-cast Al-6Ni eutectic alloy prepared in Comparative Example 2 of the present invention;

4 is a physical diagram of the die-cast aluminum alloys prepared in Examples 3 and 6 of the present invention and the Al-6Ni alloy prepared in Comparative Example 2.

Detailed ways

The invention provides a high-strength, toughness, and high-thermal-conductivity aluminum alloy suitable for die-casting, which, in terms of mass percentage, comprises: 5.0-7.0% of Ni, 0.3-3.0% of microalloying elements and the balance of Al;

The microalloying elements include one or more of Ce, Si and Cu.

In terms of mass percentage, the high-strength, toughness, and high-thermal-conductivity aluminum alloy suitable for die-casting provided by the present invention comprises 5.0-7.0% Ni, preferably 5.5-6.5%, more preferably 6.0%. The invention reduces the influence on the thermal conductivity of the aluminum alloy by adding the transition group element Ni, and utilizes its low solid solubility in the aluminum matrix to reduce the influence on the thermal conductivity of the aluminum alloy; at the same time, the Ni element and the Al element can undergo metallurgical reaction to form Al ₃ with excellent strengthening effect. Ni phase can effectively improve the mechanical properties of the alloy; the Al-Ni system with eutectic composition is selected to improve the flow filling performance of the alloy through its relatively low eutectic temperature and relatively large latent heat of crystallization, which can meet the requirements of die-casting integration mass production.

In terms of mass percentage, the high-strength, toughness, and high-thermal-conductivity aluminum alloy suitable for die-casting provided by the present invention includes 0.3-3.0% of microalloying elements. In the present invention, the microalloying elements include one or more of Ce, Si and Cu, preferably Ce, Si, Cu, Ce and Si, Ce and Cu, Si and Cu, Ce, Si and Cu One; the mass percentages of the Ce, Si and Cu are independently preferably 0.3-1.0%, more preferably 0.4-0.9%, further preferably 0.5-0.8%. In the present invention, the Ce element has high activity, which can inhibit the growth of the second phase in the aluminum alloy and achieve the effect of refining the structure, thereby significantly improving the mechanical properties and thermal conductivity of the alloy, and the solid solubility of Ce element in aluminum Low, it has relatively little influence on the flow properties of aluminum alloys; Si element has a good strengthening effect in aluminum alloys, which can significantly improve the mechanical properties of aluminum alloys. The linear shrinkage rate and volume shrinkage rate of the alloy can be reduced by controlling the addition amount of Si element, which can reduce the influence on the thermal conductivity of the aluminum alloy, so as to achieve a mutual balance between the thermal conductivity and mechanical properties of the alloy; Cu element can form Al ₂ Cu precipitation with Al It plays a significant role in dispersion strengthening, and Cu element has a certain solid solubility in the aluminum matrix, which can play a role in solid solution strengthening. At the same time, by controlling the content of Cu element, the movement of free electrons due to solid solution Cu atoms is reduced. The resulting scattering effect leads to the effect of deteriorating the thermal conductivity of the alloy, making it meet the dual requirements of electronic components for thermal conductivity and mechanical properties of thermal management materials.

In terms of mass percentage, the aluminum alloy with high strength, toughness and high thermal conductivity suitable for die-casting provided by the present invention includes the balance of Al. In the present invention, Al element is used as a matrix element.

In the invention, Ce, Cu and Si elements are used to strengthen the multi-element microalloying treatment of the aluminum alloy, and the microalloying elements are either solid-dissolved in the aluminum matrix, or form a high-quality strengthening precipitation phase, so as to improve the microstructure, morphology and distribution of the eutectic alloy. It can simultaneously improve the thermal conductivity and mechanical properties of the alloy; the addition of microalloying elements can make the Al-Ni near-eutectic melt form a wide semi-solid solidification interval under the liquidus, which will show obvious "shearing" during high pressure casting. "Thin" characteristics, reduce the viscosity, so as to ensure the excellent flow filling performance of the Al-Ni system eutectic alloy; control the microstructure and distribution of the eutectic alloy, and optimize the Al-Ni alloy under the premise of ensuring the thermal conductivity of the alloy. The mechanical properties and melt viscosity of the alloy can be reduced, and the influence of the relatively coarse eutectic structure (α-Al+Al ₃ Ni) on the elongation of the alloy is reduced.

The present invention provides a method for preparing a high-strength, high-toughness, and high-thermal-conductivity aluminum alloy suitable for die-casting according to the above technical solution, comprising the following steps:

(1) melting metal Al and Al-Ni master alloy to obtain Al-Ni alloy melt;

(2) adding a master alloy of microalloying elements to the Al-Ni alloy melt obtained in the step (1), and performing microalloy strengthening treatment to obtain a strengthened aluminum alloy melt;

(3) refining and removing slag from the strengthened aluminum alloy melt obtained in the step (2) to obtain a refining aluminum alloy melt;

(4) Performing high pressure casting on the refined aluminum alloy melt obtained in the step (3) to obtain an aluminum alloy with high strength, toughness and high thermal conductivity suitable for die casting.

In the present invention, metal Al and Al-Ni intermediate alloy are melted to obtain Al-Ni alloy melt.

In the present invention, the metal Al is preferably industrial pure Al; the Al-Ni master alloy is preferably an Al-10Ni master alloy. The present invention has no particular limitation on the specific sources of the industrial pure Al and Al-Ni master alloys, and commercially available products well known to those skilled in the art may be used. The present invention does not have a special limitation on the specific dosage of the industrial pure Al and the Al-Ni intermediate alloy, as long as the content of the Ni element can meet the requirements.

In the present invention, the melting method is preferably to first melt metal Al, and then add Al-Ni master alloy to melt; the melting temperature is preferably 690-720°C, more preferably 700-710°C. In the present invention, the melting is preferably carried out under stirring conditions. In the present invention, the melting time and stirring speed are not particularly limited, as long as each component can be mixed uniformly. In the present invention, the melting temperature is controlled within the above-mentioned range, so that it can be fully melted and mixed, and at the same time, the burning loss can be reduced.

After the melting is completed, the present invention preferably allows the melted product to stand to obtain an Al-Ni alloy melt. In the present invention, the standing time is preferably 5 to 30 minutes, more preferably 15 to 25 minutes, and even more preferably 20 minutes. In the present invention, the impurities in the melt can be floated on the surface of the melt by static treatment, thereby reducing the impurities.

After the Al-Ni alloy melt is obtained, the present invention adds a master alloy of microalloying elements to the Al-Ni alloy melt, and performs microalloy strengthening treatment to obtain a strengthened aluminum alloy melt.

In the present invention, the master alloy of microalloying elements preferably includes one or more of Al-20Ce master alloy, Al-50Cu master alloy and Al-20Si master alloy. The present invention does not specifically limit the specific source of the master alloy of the micro-alloying elements, and can use commercially available products well known to those skilled in the art or prepare them by themselves.

In the present invention, the temperature of the microalloy strengthening treatment is preferably 690-720°C, more preferably 700-710°C; the microalloy strengthening treatment time is preferably 2-20 minutes, more preferably 5-15 minutes. In the present invention, the microalloy strengthening treatment is preferably carried out under stirring conditions. The present invention does not have a special limitation on the stirring speed, as long as each component can be uniformly mixed. In the present invention, the parameters of the microalloy strengthening treatment are controlled within the above-mentioned range, so that the mixture can be fully mixed and the burning loss can be reduced at the same time.

After the microalloying strengthening treatment is finished, the present invention preferably allows the product of the microalloying strengthening treatment to stand to obtain a strengthened aluminum alloy melt. In the present invention, the standing time is preferably 5 to 30 minutes, more preferably 10 to 25 minutes, and even more preferably 15 to 20 minutes. In the present invention, the impurities in the melt can be floated on the surface of the melt by static treatment, thereby reducing the impurities.

After the strengthened aluminum alloy melt is obtained, the present invention performs refining and slag removal on the strengthened aluminum alloy melt to obtain a refined aluminum alloy melt.

In the present invention, the refining and slag removal method is preferably that a refining agent and a slag remover are sequentially added to the strengthened aluminum alloy melt. In the present invention, the refining agent is preferably a chloride salt, more preferably C ₂ Cl ₆ ; the slag removing agent is preferably a fluoride, more preferably potassium fluoroborate. In the present invention, the refining and slag removal time is preferably 10-30 min. The present invention does not specifically limit the specific amounts of the refining agent and the slag remover, which can be determined according to the technical common sense of those skilled in the art. In the present invention, impurities such as oxygen in the aluminum alloy can be removed by refining and removing slag from the aluminum alloy melt.

After the refining and slag removal is completed, in the present invention, preferably, the product of the refining and slag removal is allowed to stand and slag in sequence to obtain a refined aluminum alloy melt. In the present invention, the standing time is preferably 5-30 minutes, more preferably 10-20 minutes; the temperature of the slag removal is preferably 650-700°C, more preferably 660-690°C. The present invention does not specifically limit the specific operation of the slag removal, as long as the scum can be removed.

After the refined aluminum alloy melt is obtained, the present invention performs high pressure casting on the refined aluminum alloy melt to obtain an aluminum alloy with high strength, toughness and high thermal conductivity suitable for die casting.

In the present invention, the high-pressure casting molding is preferably performed in a cold-chamber die-casting machine. The present invention does not specifically limit the specific model of the cold chamber die casting machine, and a commercially available product well known to those skilled in the art may be used.

In the present invention, the high-pressure casting method is preferably as follows: firstly, the refined aluminum alloy melt is pressed into the die-casting melt filling chamber, and then pressed into the mold. In the present invention, the mold is preferably a preheating mold; the temperature of the mold is preferably 200-300°C, more preferably 250°C. In the present invention, the injection rate of the press-into the die-casting melt filling chamber is preferably 30-80 cm/s, more preferably 40-70 cm/s, further preferably 50-60 cm/s; The injection rate is preferably 200 to 600 cm/s, more preferably 300 to 500 cm/s, and even more preferably 400 cm/s. In the present invention, the mechanical properties of the aluminum alloy can be further improved by controlling the parameters of the high-pressure casting to be within the above range.

The preparation method provided by the invention is simple, the addition amount is easy to control, and no pollutants are discharged. Low cost and excellent comprehensive performance.

The technical solutions of the present invention will be clearly and completely described below with reference to the embodiments of the present invention. Obviously, the described embodiments are only some, but not all, embodiments of the present invention. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative efforts shall fall within the protection scope of the present invention.

Example 1

A high-strength, tough, and high-thermal-conductivity aluminum alloy suitable for die-casting, in terms of mass percentage, the composition is: 6.0% of Ni, 0.5% of Ce and the balance of Al;

The preparation method of the high-strength, toughness, and high-thermal-conductivity aluminum alloy suitable for die-casting is composed of the following steps:

(1) melting industrial pure Al, then adding Al-10Ni master alloy, stirring for 20min, and then standing for 20min to obtain Al-Ni alloy melt; the melting temperature is 700°C;

(2) adding Al-20Ce master alloy to the Al-Ni alloy melt obtained in the step (1), stirring for 5 minutes to carry out microalloy strengthening treatment, and then standing for 15 minutes to obtain a strengthened aluminum alloy melt; the microalloying The temperature of strengthening treatment is 700℃;

(3) adding a refining agent and a slag removing agent to the strengthened aluminum alloy melt obtained in the step (2) successively to carry out refining and removing slag, and after removing the slag, a refining aluminum alloy melt is obtained; the refining agent is C ₂ Cl ₆ , the slag removal agent is potassium fluoroborate; the temperature of the refining and slag removal is 690°C, and the time of the refining and slag removal is 20min;

(4) injecting the refined aluminum alloy melt obtained in the step (3) into a cold chamber die casting machine, then press it into the die casting melt filling chamber, and then press it into a mold with a preheating temperature of 250° C. to obtain a suitable High strength, toughness and high thermal conductivity aluminum alloy formed by die casting; the injection rate of the injection into the die-casting melt filling chamber is 50cm/s; the injection rate of the injection into the mold is 400cm/s; the mold is the wall thickness 5-inch mobile phone backplane mold less than 1mm.

The high-strength, toughness, and high-thermal-conductivity aluminum alloy suitable for die-casting prepared in Example 1 is a die-cast Al-6Ni-0.5Ce alloy. The mechanical and thermal conductivity of the high-strength, toughness, and high thermal conductivity aluminum alloy suitable for die-casting prepared in Example 1 was carried out. Performance test, the test results show that the thermal conductivity of the die-cast A1-6Ni-0.5Ce alloy is 223W/(m·K); the yield strength is 145MPa, the tensile strength is 228MPa, and the elongation is 27%. Compared with Comparative Example 2, the thermal conductivity is increased by about 3.7%, the tensile strength is increased by about 11%, and the elongation is increased by 8.0%. The melt viscosity test was carried out in the liquid state of the alloy. The test results showed that the viscosity value of the melt was 1.15Pa s (@645℃) at a rotational speed of 10s ^-1 . Compared with the comparative example 2, the melt viscosity of the alloy melt was Viscosity values decreased by 3.4%. It is explained that the technical scheme of the present invention can improve the thermal conductivity, mechanical properties and flow forming ability of the aluminum alloy.

Example 2

A high-strength, tough, and high-thermal-conductivity aluminum alloy suitable for die-casting, in terms of mass percentage, the composition is: 6.0% of Ni, 0.5% of Cu and the balance of Al;

The preparation method of the high-strength, toughness, and high-thermal-conductivity aluminum alloy suitable for die-casting is composed of the following steps:

(1) melting industrial pure Al, then adding Al-10Ni master alloy, stirring for 20min, and then standing for 20min to obtain Al-Ni alloy melt; the melting temperature is 700°C;

(2) adding Al-50Cu master alloy to the Al-Ni alloy melt obtained in the step (1), stirring for 5 minutes to carry out microalloy strengthening treatment, and then standing for 15 minutes to obtain a strengthened aluminum alloy melt; the microalloying The temperature of strengthening treatment is 700℃;

(3) adding a refining agent and a slag removing agent to the strengthened aluminum alloy melt obtained in the step (2) successively to carry out refining and removing slag, and after removing the slag, a refining aluminum alloy melt is obtained; the refining agent is C ₂ Cl ₆ , the slag removal agent is potassium fluoroborate; the temperature of the refining and slag removal is 690°C, and the time of the refining and slag removal is 20min;

(4) injecting the refined aluminum alloy melt obtained in the step (3) into a cold chamber die casting machine, then press it into the die casting melt filling chamber, and then press it into a mold with a preheating temperature of 250° C. to obtain a suitable High strength, toughness and high thermal conductivity aluminum alloy formed by die casting; the injection rate of the injection into the die-casting melt filling chamber is 50cm/s; the injection rate of the injection into the mold is 400cm/s; the mold is the wall thickness 5-inch mobile phone backplane mold less than 1mm.

The high-strength, toughness, and high-thermal-conductivity aluminum alloy suitable for die-casting prepared in Example 2 is a die-cast A1-6Ni-0.5Cu alloy, and the mechanical and thermal conductivity of the high-strength, toughness, and high thermal conductivity aluminum alloy suitable for die-casting prepared in Example 2 is carried out. Performance test, the test results show that the thermal conductivity of the die-cast A1-6Ni-0.5Cu alloy is 216W/(m·K); the yield strength is 152MPa, the tensile strength is 234MPa, and the elongation is 26.5%. Compared with Comparative Example 2, although the increase in thermal conductivity is lower, the increase in tensile strength is about 14%, and the elongation is increased by 6%. The melt viscosity test was carried out in the liquid state of the alloy. The test results showed that the viscosity value of the melt was 1.21Pa s (@645℃) at a rotational speed of 10s ^-1 . Compared with the comparative example 1, the melt viscosity of the alloy melt was Viscosity values decreased by 3.2%. It is explained that the technical scheme of the present invention can improve the mechanical properties and flow forming ability of the aluminum alloy.

Example 3

A high-strength, tough, and high-thermal-conductivity aluminum alloy suitable for die-casting, in terms of mass percentage, the composition is: 6.0% of Ni, 0.5% of Si and the balance of Al;

The preparation method of the high-strength, toughness, and high-thermal-conductivity aluminum alloy suitable for die-casting is composed of the following steps:

(1) melting industrial pure Al, then adding Al-10Ni master alloy, stirring for 20min, and then standing for 20min to obtain Al-Ni alloy melt; the melting temperature is 710°C;

(2) adding Al-20Si master alloy to the Al-Ni alloy melt obtained in the step (1), stirring for 5 minutes to carry out microalloy strengthening treatment, and then standing for 15 minutes to obtain a strengthened aluminum alloy melt; the microalloying The temperature of strengthening treatment is 710℃;

(3) adding a refining agent and a slag removing agent to the strengthened aluminum alloy melt obtained in the step (2) successively to carry out refining and removing slag, and after removing the slag, a refining aluminum alloy melt is obtained; the refining agent is C ₂ Cl ₆ , the slag removal agent is potassium fluoroborate; the temperature of the refining and slag removal is 690°C, and the time of the refining and slag removal is 30min;

(4) injecting the refined aluminum alloy melt obtained in the step (3) into a cold chamber die casting machine, then press it into the die casting melt filling chamber, and then press it into a mold with a preheating temperature of 250° C. to obtain a suitable High strength, toughness and high thermal conductivity aluminum alloy formed by die casting; the injection rate of the injection into the die-casting melt filling chamber is 50cm/s; the injection rate of the injection into the mold is 400cm/s; the mold is the wall thickness 5-inch mobile phone backplane mold less than 1mm.

The high-strength, toughness, and high thermal conductivity aluminum alloy suitable for die-casting prepared in Example 3 is an Al-6Ni-0.5Si alloy in the die-cast state. Performance test, the test results show that the thermal conductivity of the die-cast A1-6Ni-0.5Si alloy is 220W/(m·K); the yield strength is 148MPa, the tensile strength is 227MPa, and the elongation is 27.5%. Compared with Comparative Example 2, the thermal conductivity is increased by 2.3%, the tensile strength is increased by about 11%, and the elongation is increased by 10%. The melt viscosity test was carried out in the liquid state of the alloy. The test results showed that the viscosity value of the melt was 1.08Pa s (@645℃) at a rotational speed of 10s ^-1 . Compared with the comparative example 2, the melt viscosity of the alloy melt was Viscosity values decreased by 9%. It shows that the technical solution of the present invention can improve the thermal conductivity, mechanical properties and flow forming ability of the aluminum alloy, and the alloy parts obtained by die casting have good surface quality and few surface defects.

Example 4

A high-strength, tough, and high-thermal-conductivity aluminum alloy suitable for die-casting, in terms of mass percentage, the composition is: 6.0% Ni, 0.5% Ce, 0.3% Si, 1.0% Cu and the balance of Al;

The preparation method of the high-strength, toughness, and high-thermal-conductivity aluminum alloy suitable for die-casting is composed of the following steps:

(1) melting industrial pure Al, then adding Al-10Ni master alloy, stirring for 20min, then standing for 20min to obtain Al-Ni alloy melt; the melting temperature is 720°C;

(2) Add Al-20Ce master alloy, Al-50Cu master alloy and Al-20Si master alloy to the Al-Ni alloy melt obtained in the step (1) in turn, stir for 10min to carry out microalloy strengthening treatment, and then let stand 20min to obtain a strengthened aluminum alloy melt; the temperature of the microalloy strengthening treatment is 720°C;

(3) adding a refining agent and a slag removing agent to the strengthened aluminum alloy melt obtained in the step (2) successively to carry out refining and removing slag, and after removing the slag, a refining aluminum alloy melt is obtained; the refining agent is C ₂ Cl ₆ , the slag removal agent is potassium fluoroborate; the temperature of the refining and slag removal is 690°C, and the time of the refining and slag removal is 30min;

(4) injecting the refined aluminum alloy melt obtained in the step (3) into a cold chamber die casting machine, then press it into the die casting melt filling chamber, and then press it into a mold with a preheating temperature of 250° C. to obtain a suitable High strength, toughness and high thermal conductivity aluminum alloy formed by die casting; the injection rate of the injection into the die-casting melt filling chamber is 50cm/s; the injection rate of the injection into the mold is 400cm/s; the mold is the wall thickness 5-inch mobile phone backplane mold less than 1mm.

The high-strength, toughness, and high-thermal-conductivity aluminum alloy suitable for die-casting prepared in Example 4 is a die-cast A1-7Ni-0.5Ce-0.3Si-1.0Cu alloy. The mechanical and thermal properties of the aluminum alloy were tested. The test results showed that the thermal conductivity of the die-cast A1-7Ni-0.5Ce-0.3Si-1.0Cu alloy was 210W/(m K); the yield strength was 165MPa, and the tensile strength was 255MPa , the elongation is 26.0%. Compared with Comparative Example 2, although the thermal conductivity is reduced by 2.3%, the tensile strength is greatly improved by about 24%, and the elongation is increased by 4%. The melt viscosity test was carried out in the liquid state of the alloy. The test results showed that the viscosity value of the melt was 1.12Pa s (@645℃) at a rotational speed of 10s ^-1 . Viscosity values decreased by 5.9%. It is explained that the technical scheme of the present invention can improve the thermal conductivity, mechanical properties and flow forming ability of the aluminum alloy.

Example 5

A high-strength, tough, and high-thermal-conductivity aluminum alloy suitable for die-casting, in terms of mass percentage, the composition is: 6.0% of Ni, 0.5% of Ce, 1.0% of Si, 0.3% of Cu and the balance of Al;

The preparation method of the high-strength, toughness, and high-thermal-conductivity aluminum alloy suitable for die-casting is composed of the following steps:

(1) melting industrial pure Al, then adding Al-10Ni master alloy, stirring for 20min, and then standing for 20min to obtain Al-Ni alloy melt; the melting temperature is 710°C;

(2) Add Al-20Ce master alloy, Al-50Cu master alloy and Al-20Si master alloy to the Al-Ni alloy melt obtained in the step (1) in turn, stir for 15min to carry out microalloy strengthening treatment, and then let stand 30min to obtain a strengthened aluminum alloy melt; the temperature of the microalloy strengthening treatment is 710°C;

(3) adding a refining agent and a slag remover to the strengthened aluminum alloy melt obtained in the step (2) successively for refining and removing slag, and then cooling to 690° C. for slag removal to obtain a refining aluminum alloy melt; the refining The agent is C ₂ Cl ₆ , and the slag removing agent is potassium fluoroborate; the time for refining and removing slag is 20min;

(4) injecting the refined aluminum alloy melt obtained in the step (3) into a cold chamber die casting machine, then press it into the die casting melt filling chamber, and then press it into a mold with a preheating temperature of 250° C. to obtain a suitable High strength, toughness and high thermal conductivity aluminum alloy formed by die casting; the injection rate of the injection into the die-casting melt filling chamber is 50cm/s; the injection rate of the injection into the mold is 400cm/s; the mold is the wall thickness 5-inch mobile phone backplane mold less than 1mm.

The high-strength, toughness, and high-thermal-conductivity aluminum alloy suitable for die-casting prepared in Example 5 is a die-cast A1-6Ni-0.5Ce-1.0Si-0.3Cu alloy. The mechanical and thermal conductivity properties of the aluminum alloy were tested. The test results showed that the thermal conductivity of the die-cast A1-6Ni-0.5Ce-1.0Si-0.3Cu alloy was 212W/(m·K); the yield strength was 162MPa, and the tensile strength was 248MPa. , the elongation is 26.5%. Compared with Comparative Example 2, although the thermal conductivity is reduced by 1.4%, the tensile strength is increased by about 21%, and the elongation is increased by 6%. The melt viscosity test was carried out in the liquid state of the alloy. The test results showed that the viscosity value of the melt was 1.09Pa s (@645℃) at a rotational speed of 10s ^-1 . Compared with the comparative example 2, the melt viscosity of the alloy melt was Viscosity values decreased by 8.4%. It is explained that the technical scheme of the present invention can improve the thermal conductivity, mechanical properties and flow forming ability of the aluminum alloy.

Example 6

A high-strength, tough, and high-thermal-conductivity aluminum alloy suitable for die-casting, in terms of mass percentage, the composition is: 5.0% Ni, 0.5% Ce, 1.0% Si, 1.0% Cu and the balance of Al;

The preparation method of the high-strength, toughness, and high-thermal-conductivity aluminum alloy suitable for die-casting is composed of the following steps:

(1) Melting industrial pure Al, then adding Al-10Ni master alloy, stirring for 15min, then standing for 20min to obtain Al-Ni alloy melt; the melting temperature is 720°C;

(2) Add Al-20Ce master alloy, Al-50Cu master alloy and Al-20Si master alloy to the Al-Ni alloy melt obtained in the step (1) in turn, stir for 20min to carry out microalloy strengthening treatment, and then let stand 30min to obtain a strengthened aluminum alloy melt; the temperature of the microalloy strengthening treatment is 720°C;

(3) adding a refining agent and a slag remover to the strengthened aluminum alloy melt obtained in the step (2) successively for refining and removing slag, and then cooling to 690° C. for slag removal to obtain a refining aluminum alloy melt; the refining The agent is C ₂ Cl ₆ , and the slag removing agent is potassium fluoroborate; the time for refining and removing slag is 20min;

(4) injecting the refined aluminum alloy melt obtained in the step (3) into a cold chamber die casting machine, then press it into the die casting melt filling chamber, and then press it into a mold with a preheating temperature of 250° C. to obtain a suitable High strength, toughness and high thermal conductivity aluminum alloy formed by die casting; the injection rate of the injection into the die-casting melt filling chamber is 50cm/s; the injection rate of the injection into the mold is 400cm/s; the mold is the wall thickness 5-inch mobile phone backplane mold less than 1mm.

The high-strength, toughness, and high-thermal-conductivity aluminum alloy suitable for die-casting prepared in Example 6 is a die-cast A1-5Ni-0.5Ce-1.0Si-1.0Cu alloy. The mechanical and thermal conductivity properties of the aluminum alloy were tested. The test results showed that the thermal conductivity of the die-cast A1-5Ni-0.5Ce-1.0Si-1.0Cu alloy was 215W/(m K); the yield strength was 165MPa, and the tensile strength was 259MPa , the elongation is 25.5%. Compared with Comparative Example 2, although the thermal conductivity does not change, the tensile strength is increased by about 26%, and the elongation is increased by 2%. The melt viscosity test was carried out in the liquid state of the alloy. The test results showed that the viscosity value of the melt was 1.11Pa·s (@645℃) at a rotational speed of 10s ^-1 . Compared with the comparative example 2, the melt viscosity of the alloy melt was Viscosity values decreased by 6.7%. It shows that the technical scheme of the present invention can improve the thermal conductivity, mechanical properties and flow forming ability of the aluminum alloy, and the alloy parts obtained by die casting have fewer surface defects.

Comparative Example 1

Commercial A356 aluminum alloy, the composition by mass percentage is: Si: 7.0%, Mg: 0.35%, Fe: 0.1%, and the rest is Al;

The preparation method of the commercial A356 alloy is as follows:

(1) Melt the weighed A356 alloy at a melting temperature of 720° C. After all melting, manually stir for 10 minutes to make the composition uniform, and leave it to stand for 30 minutes to obtain an aluminum alloy melt;

(2) adding refining agent and slag remover successively to the aluminum alloy melt obtained in the step (1), carrying out refining treatment, leaving standstill for 10 min, and then cooling to 690° C. and then removing slag to obtain refined aluminum alloy melt;

(3) injecting the refined aluminum alloy melt obtained in the step (3) into a cold chamber die casting machine, then pressing it into the die casting melt filling chamber, and then pressing it into a mold with a preheating temperature of 250° C. to obtain a commercial A356 aluminum alloy; the injection rate of the injection into the die-casting melt filling chamber is 50cm/s; the injection rate of the injection into the mold is 400cm/s; the mold is a 5-inch mobile phone back with a wall thickness of less than 1mm plate mold.

The commercial A356 aluminum alloy prepared in Comparative Example 1 is a die-cast A356 aluminum alloy. The mechanical and thermal conductivity tests of the commercial A356 aluminum alloy prepared in Comparative Example 1 show that the thermal conductivity of the commercial A356 aluminum alloy is 125W/(m ·K); the yield strength is 155MPa, the tensile strength is 215MPa and the elongation is 8%. The melt viscosity test was carried out in the liquid state of the alloy, and the test results showed that the melt viscosity value was 1.25Pa·s (@645℃) at the rotational speed of 10s ^-1 .

Comparative Example 2

A1-6Ni alloy, the composition by mass percentage is: Ni: 6.0%, and the rest is Al;

The preparation method of the A1-6Ni alloy is as follows:

(1) melting industrial pure Al, then adding Al-10Ni master alloy, stirring for 20min, and then standing for 20min to obtain Al-Ni alloy melt; the melting temperature is 700°C;

(2) adding a refining agent and a slag remover to the Al-Ni alloy melt obtained in the step (1) successively for refining and removing slag, and then cooling to 690° C. for slag removal to obtain a refining aluminum alloy melt; the The refining agent is C ₂ Cl ₆ , and the slag removing agent is potassium fluoroborate; the refining and slag removing time is 20 minutes;

(3) injecting the refined aluminum alloy melt obtained in the step (2) into a cold chamber die casting machine, then press it into the die casting melt filling chamber, and then press it into a mold with a preheating temperature of 250° C. to obtain a suitable High strength, toughness and high thermal conductivity aluminum alloy formed by die casting; the injection rate of the injection into the die-casting melt filling chamber is 50cm/s; the injection rate of the injection into the mold is 400cm/s; the mold is the wall thickness 5-inch mobile phone backplane mold less than 1mm.

The A1-6Ni alloy prepared in Comparative Example 2 is a die-cast A1-6Ni eutectic alloy. The die-cast A1-6Ni eutectic alloy prepared in Comparative Example 2 was tested for mechanical and thermal conductivity. The test results showed that the die-cast A1-6Ni eutectic alloy was The thermal conductivity of the eutectic alloy is 215W/(m·K); the yield strength is 130MPa, the tensile strength is 205MPa, and the elongation is 25%. The melt viscosity test was carried out in the liquid state of the alloy, and the test results showed that the viscosity value of the melt was 1.19 Pa·s (@645°C) at a rotational speed of 10s ^-1 . It is worth noting that although the A1-6Ni alloy prepared in Comparative Example 2 is used for die casting, there are obvious defects on the surface of the casting.

The properties of the aluminum alloys prepared in Examples 1-6 and Comparative Examples 1-2 are shown in Table 1:

Table 1 Properties of the aluminum alloys prepared in Examples 1-6 and Comparative Examples 1-2

The improvement range of the performance of the aluminum alloys prepared in Examples 1 to 6 relative to the comparative example is shown in Table 2:

It can be seen from the records in Table 1 and Table 2 that the technical solution of the present invention can greatly improve the mechanical properties of the aluminum alloy and reduce the viscosity of the aluminum alloy under the condition that the variation range of the thermal conductivity of the aluminum alloy is small; It can be seen from the data records in Example 2 that Cu element has a good strengthening effect on the Al-Ni alloy, significantly improves the mechanical properties of the alloy, and slightly improves its thermal conductivity, but it helps the flow forming ability of the aluminum alloy. low effect.

The optical microstructure of the die-cast A1-5Ni-0.5Ce-1.0Si-1.0Cu alloy prepared in Example 6 is shown in FIG. 1 . It can be seen from Figure 1 that the α-Al (white) grains in the microstructure are uniformly distributed, and there are granular second phases (black) in the size range of 1 to 10 μm. The uniformly distributed Al grains have high thermal conductivity to them. Advantageously, the uniformly distributed precipitation phase components are Ni and Si, and their dispersion distribution is favorable for improving the strength and toughness of the alloy, and the blocking effect of hot electron and phonon transmission in the granular second opposing material is small.

The optical microstructure of the die-cast A356 alloy prepared in Comparative Example 1 is shown in FIG. 2 . It can be seen from Figure 2 that the phase of the die-cast A356 alloy is mainly composed of primary α-Al phase and eutectic Si phase, and the eutectic Si phase mainly exists in the form of discrete laths; combined with the Al-Si binary phase diagram As well as the principle of non-equilibrium solidification, part of Si exists in the form of solid solution in α-Al. Therefore, Si in the form of solid solution and second phase affects the thermal conductivity of the alloy, hinders the movement of heat-transfer electrons and phonons, and reduces die casting. Thermal conductivity of as-state alloys.

Figure 3 shows the optical microstructure of the die-cast Al-6Ni eutectic alloy prepared in Comparative Example 2. It can be seen from Figure 3 that the α-Al grains (white) have better dispersion uniformity, and the grain size is smaller than that in Figure 1. The decrease in grain size means that the number of grain boundaries increases, and the grain boundaries are more sensitive to hot electrons and phonons. Transmission has a certain hindering effect. Furthermore, the α-Al grains in Fig. 3 are obviously dendritic, and their sphericity is not as good as that in Fig. 1. The dendritic grains are unfavorable for the low viscosity of the melt in the semi-solid state. Figure 3 shows no precipitation of the granular second phase, so the tensile strength and elongation are low.

Figure 4 shows the physical images of the die-cast aluminum alloys prepared in Examples 3 and 6 and the Al-6Ni alloy prepared in Comparative Example 2. In Figure 4, (a) is the Al-6Ni- alloy prepared in Example 3. 0.5Si alloy, (b) is the Al-5Ni-0.5Ce-1.0Si-1.0Cu alloy prepared in Example 6, (c) is the Al-6Ni alloy prepared in Comparative Example 2, and the average wall thickness of the alloy is 0.8 mm. It can be seen from Figure 4 that the Al-6Ni-0.5Si alloy parts prepared in Example 3 have a smooth surface and no obvious hot cracks, and the Al-5Ni-0.5Ce-1.0Si-1.0Cu alloy prepared in Example 6 has a smooth surface and is hot. The cracks are very few and inconspicuous, and will not significantly affect the appearance and properties of the alloy. The surface of the Al-6Ni alloy prepared in Comparative Example 2 is smooth but has obvious hot cracks (marked by arrows in the figure). It can be seen that the aluminum alloy provided by the present invention has a lower viscosity coefficient of the alloy melt at the die-casting temperature, which is favorable for its forming and defect avoidance.

The above are only the preferred embodiments of the present invention. It should be pointed out that for those skilled in the art, without departing from the principles of the present invention, several improvements and modifications can be made. It should be regarded as the protection scope of the present invention.

Claims (10)

1. A high-strength, high-toughness and high-heat-conductivity aluminum alloy suitable for die-casting molding comprises the following components in percentage by mass: 5.0-7.0% of Ni, 0.3-3.0% of microalloy elements and the balance of Al;

the microalloying element comprises one or more of Ce, Si and Cu.

2. The high-strength high-toughness high-thermal-conductivity aluminum alloy suitable for die-casting according to claim 1, wherein the mass percentages of Ce, Si and Cu are independently 0.3-1.0%.

3. The preparation method of the high-strength high-toughness high-heat-conductivity aluminum alloy suitable for die-casting molding according to any one of claims 1 to 2, comprising the following steps:

(1) melting metal Al and Al-Ni intermediate alloy to obtain Al-Ni alloy melt;

(2) adding an intermediate alloy of micro-alloy elements into the Al-Ni alloy melt obtained in the step (1), and performing micro-alloy strengthening treatment to obtain a strengthened aluminum alloy melt;

(3) refining and deslagging the reinforced aluminum alloy melt obtained in the step (2) to obtain a refined aluminum alloy melt;

(4) and (4) carrying out high-pressure casting molding on the refined aluminum alloy melt obtained in the step (3) to obtain the high-strength high-toughness high-heat-conductivity aluminum alloy suitable for pressure casting molding.

4. The production method according to claim 3, wherein the Al-Ni master alloy in the step (1) is an Al-10Ni master alloy.

5. The method according to claim 3, wherein the melting temperature in the step (1) is 690 to 720 ℃.

6. The preparation method of claim 3, wherein the master alloy of the microalloying element in the step (2) comprises one or more of Al-20Ce master alloy, Al-50Cu master alloy and Al-20Si master alloy.

7. The preparation method according to claim 3, wherein the temperature of the microalloy strengthening treatment in the step (2) is 690-720 ℃.

8. The manufacturing method according to claim 3, characterized in that the refining deslagging in the step (3) is performed by sequentially adding a refining agent and a deslagging agent to the strengthened aluminum alloy melt.

9. The production method according to claim 3, wherein the high-pressure casting molding in the step (4) is performed by: the refined aluminum alloy melt is firstly pressed into a die-casting melt filling chamber and then pressed into a die.

10. A production method according to claim 9, wherein the injection rate of said pressing into the die-casting melt filling chamber is 30 to 80cm/s, and the injection rate of said pressing into the die is 200 to 600 cm/s.

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