CN112030045A - Hypoeutectic aluminum-silicon alloy and preparation method thereof - Google Patents

Abstract

The invention relates to a hypoeutectic aluminum-silicon alloy and a preparation method thereof, belonging to the technical field of alloys. The technical problem of how to improve the mechanical properties and thermal conductivity of the existing hypoeutectic Al-Si alloys is solved. The hypoeutectic Al-Si alloy of the present invention is composed of 91.3wt% Al, 8wt% Si, 0.6wt% Mg and 0.1wt% Cu, which adopts pure Al and Al-Si master alloy to smelt raw material in a resistance furnace The aluminum liquid is then added with Al-Cu master alloy and pure Mg for alloying, and then undergoes modification and air blowing to remove slag. Finally, it is poured and prepared by T6 heat treatment. The hypoeutectic aluminum-silicon alloy has high thermal conductivity, high electrical conductivity and high strength and toughness; the preparation method has simple process and high production efficiency.

Description

A kind of hypoeutectic aluminum-silicon alloy and preparation method thereof

technical field

The invention belongs to the technical field of alloys, and in particular relates to a hypoeutectic aluminum-silicon alloy and a preparation method thereof.

Background technique

Aluminum silicon alloy (Al-Si alloy) is a forging and casting alloy mainly composed of aluminum and silicon. Generally, the silicon content is 11wt%. At the same time, a small amount of copper, iron and nickel are added to improve the strength and density. It is about 2.6-2.7g/cm ³ , the thermal conductivity is about 101-126W/(m·°C), the Young's modulus is 71.0GPa, the impact value is about 7-8.5J, and the fatigue limit is ±45MPa.

Due to its light weight, good thermal conductivity, and certain strength, hardness and corrosion resistance, Al-Si alloys are widely used in important industries such as aviation, transportation, construction, and automobiles. Castings, such as cover plates, motor housings, brackets, etc., are also used as brazing solders.

Al-Si alloy is a typical eutectic alloy without intermediate compounds. However, in the hypoeutectic Al-Si alloy, the eutectic silicon is in the form of coarse needles, which severely splits the matrix, which reduces its mechanical properties and cannot meet the needs of practical applications. And with the development of 5G technology, the power consumption of signal transmission has increased significantly. For components such as base station radiators, the current aluminum-silicon alloys have gradually been unable to meet the needs of the industry, and higher requirements have been placed on thermal conductivity.

SUMMARY OF THE INVENTION

In view of this, in order to improve the mechanical properties and thermal conductivity of the existing hypoeutectic aluminum-silicon alloy, the present invention provides a hypoeutectic aluminum-silicon alloy and a preparation method thereof.

In order to achieve the above object, the present invention adopts the following technical solutions:

The invention provides a hypoeutectic aluminum-silicon alloy, which is composed of 91.3wt% Al, 8wt% Si, 0.6wt% Mg and 0.1wt% Cu.

The present invention also provides a method for preparing the above-mentioned hypoeutectic aluminum-silicon alloy, comprising the following steps:

Step 1. Weigh pure Al, Al-Si alloy, Al-Cu alloy, pure Mg and Al-Sr alloy according to the composition, and the addition amount of Sr is 0.08% of the alloy liquid mass;

Step 2, smelting pure Al, Al-Si alloy, Al-Cu alloy and pure Mg to obtain alloy liquid;

Step 3, adding Al-Sr alloy to the alloy liquid, smelting and stirring evenly, and keeping the temperature for 15 minutes to obtain a deteriorated alloy liquid;

Step 4: After the alloy liquid is subjected to air blowing and slag removal, pouring, and T6 treatment in sequence, a hypoeutectic aluminum-silicon alloy is obtained.

Preferably, the purity of pure Al is ≥99.8%, the purity of Al-Si alloy is 24.4%, the purity of Al-Cu alloy is 50%, the purity of pure Mg is ≥99.8%, and the purity of Al-Sr alloy is 10% %.

Preferably, before the second step, pure Al, Al-Si alloy, Al-Cu alloy and pure Mg are preheated to 200°C.

Preferably, the process of the second step is as follows: adding pure Al and Al-Si alloy to the resistance furnace, heating up to 780°C for smelting and stirring evenly to obtain primary aluminum liquid, cooling to 750°C, adding to the primary aluminum liquid Add Al-Cu alloy for smelting and stir evenly, after holding for 5 minutes, add pure Mg for smelting and stir evenly to obtain alloy liquid.

Preferably, before the third step, the Al-Sr alloy is preheated to 200°C.

Preferably, in the fourth step, the process of blowing air to remove slag is as follows: introducing high-purity argon gas into the deteriorated alloy liquid, blowing air for 2 minutes, skimming the slag, and resting for 2 minutes.

Preferably, in the fourth step, the pouring process is as follows: pouring the alloy liquid after blowing and removing slag into a mold preheated to 200° C. and cooling naturally.

Preferably, in the fourth step, the process of T6 treatment is as follows: the casting obtained after casting is put into water at 25°C within 5s after solid solution at 535°C for 4h, and then aged at 170°C for 3 hours, taken out, and cooled in air. to 25°C.

Compared with the prior art, the advantages of the present invention are:

The preparation method of the hypoeutectic aluminum-silicon alloy of the present invention refines the eutectic silicon and reduces the staggered connection by modifying the hypoeutectic aluminum-silicon alloy, and then fuses the eutectic silicon or even spheroidizes the eutectic silicon through heat treatment, which greatly increases the The electronic channel can improve the thermal conductivity and the strength and toughness of the aluminum-silicon alloy. Experiments show that the hypoeutectic aluminum-silicon alloy of the present invention has thermal conductivity and electrical conductivity increased from 145.91W/(m·K) and 33.43%IACS to 169.00W/(m·K, respectively, compared with the unmodified aluminum-silicon alloy. ), 40.22% IACS; yield strength, tensile strength and elongation increased from 131.5Mpa, 217.5Mpa and 3.02% to 250.46Mpa, 311.3Mpa and 7.8%, respectively.

The preparation method of the hypoeutectic aluminum-silicon alloy of the present invention is simple in process, only needs to strictly match the alloy components, and the alloy performance can be improved in the as-cast state and T6 treatment after one-time metamorphism, which simplifies the process flow and improves the production efficiency.

The preparation method of the hypoeutectic aluminum-silicon alloy of the present invention does not need large-scale equipment of other casting methods, does not need to use precious metals, reduces the production cost and improves the economic benefit.

Description of drawings

In order to illustrate the technical solutions in the embodiments of the present invention more clearly, the following briefly introduces the accompanying drawings used in the embodiments. Obviously, the drawings in the following description are only some embodiments of the present invention. For those of ordinary skill in the art, other drawings can also be obtained from these drawings without any creative effort.

Fig. 1 is the mechanical tensile curve diagram of the aluminum-silicon alloy prepared in Example 1 of the present invention and Comparative Example 1;

FIG. 2 is the change curve of thermal conductivity and electrical conductivity of the aluminum-silicon alloys prepared in Example 1 and Comparative Example 1 of the present invention.

Detailed ways

In order to further understand the present invention, the preferred embodiments of the present invention are described below in conjunction with specific embodiments, but it should be understood that these descriptions are only for further illustrating the features and advantages of the present invention rather than limiting the patent requirements of the present invention.

The hypoeutectic Al-Si alloy of the present invention is composed of 91.3wt% Al, 8wt% Si, 0.6wt% Mg and 0.1wt% Cu.

The preparation method of the hypoeutectic aluminum-silicon alloy of the present invention comprises the following steps:

Step 1. Weigh pure Al, Al-Si alloy, Al-Cu alloy, pure Mg and Al-Sr alloy according to the composition, and the addition amount of Sr is 0.08% of the alloy liquid mass;

Step 2: Preheat pure Al, Al-Si alloy, Al-Cu alloy and pure Mg to 200 °C, add pure Al and Al-Si alloy to the resistance furnace, heat up to 780 °C for smelting and stir evenly to obtain the original The aluminum liquid is cooled to 750°C, and Al-Cu alloy is added to the primary aluminum liquid for smelting and stirring. After holding for 5 minutes, pure Mg is added for melting and stirring to obtain an alloy liquid.

Step 3: Preheating the Al-Sr alloy to 200° C. and adding it to the alloy liquid, smelting and stirring evenly, and keeping the temperature for 15 minutes to obtain the deteriorated alloy liquid;

Step 4: Pour high-purity argon gas into the deteriorated alloy liquid, and after blowing for 2 minutes, skim the slag (the slag skimming spoon needs to be coated with zinc oxide and preheated), and stand still for 2 minutes to obtain a alloy liquid;

Step 5, pouring the alloy liquid after blowing and removing slag into a mold preheated to 200°C, and cooling naturally to obtain a casting;

Step 6: After solid solution at 535°C for 4 hours, the casting is put into a water tank at room temperature and 25°C for water quenching within 5s, then aged at 170°C for 3 hours, taken out, and air-cooled to room temperature of 25°C to obtain a hypoeutectic aluminum-silicon alloy.

In the above technical solution, the purity of pure Al is ≥99.8%, the purity of Al-Si alloy is 24.4%, the purity of Al-Cu alloy is 50%, the purity of pure Mg is ≥99.8%, and the purity of Al-Sr alloy is 10%. . Pure Al, Al-Si alloys, Al-Cu alloys, pure Mg and Al-Sr alloys are all commercially available. Pure Al, the mass percentage of its chemical composition Fe<0.1002%, Si<0.0030%, Cu<0.003%, Sn<0.001%, Ti<0.001%, balance: Al. Al-Si alloy, the mass percentage of its chemical composition Si: 24.4%, Fe<0.09%, Ti<0.002%, P<0.0015%, balance: Al. Al-Cu alloy, the mass percentage of its chemical composition is Cu: 50%, Ti < 0.05%, V < 0.05%, B < 0.02, balance: Al. Pure Mg, the mass percentage of its chemical composition Fe<0.004%, Si<0.005, Cu<0.003, Al<0.006, balance: Mg. Al-Sr alloy, the mass percentage of its chemical composition is Sr: 9.98%, Fe<0.18%, Ca<0.007, Cu<0.003, balance: Al.

Terms used in the present invention generally have the meanings commonly understood by those of ordinary skill in the art, unless otherwise specified.

In order to make those skilled in the art better understand the technical solutions of the present invention, the present invention will be further described in detail below with reference to the embodiments.

In the following examples, various procedures and methods not described in detail are conventional methods well known in the art. The materials, reagents, devices, instruments, equipment, etc. used in the following examples can be obtained from commercial sources unless otherwise specified.

Example 1

The preparation method of hypoeutectic aluminum-silicon alloy comprises the following steps:

Step 1. Add 786g of pure Al and 393g of Al-Si alloy preheated to 200°C into the graphite crucible of the resistance furnace, and heat up to 780°C for smelting to obtain primary aluminum liquid;

Step 2: After cooling the primary aluminum liquid to 750°C, add 2.4g of Al-Cu alloy preheated to 200°C to the primary aluminum liquid for smelting and stirring, and after holding for 5 minutes, add 8.7g pure Mg (preheated to 200°C) 20% burning loss) smelting and stirring to obtain alloy liquid;

Step 3. Add 9.6g of Al-Sr alloy (Sr: 9.98%, Fe<0.18%, Ca<0.007, Cu<0.003, balance: Al) into the crucible and preheat to 200°C, then add it to the alloy liquid After stirring until all melted and uniform, keep the temperature for 15 minutes to obtain the alloy liquid after metamorphism;

Step 4: Passing the alloy liquid into high-purity argon gas for blowing for 2 minutes, skimming the slag, and letting it stand for 2 minutes to obtain the alloy liquid after the slag removal;

Step 5, pouring the alloy liquid after slag removal into a mold preheated to 200°C in advance, and cooling naturally to obtain a casting;

Step 6: After solid solution at 535°C for 4 hours, the casting is put into a water tank at room temperature and 25°C for water quenching within 5s, then aged at 170°C for 3 hours, taken out, and air-cooled to room temperature of 25°C to obtain a hypoeutectic aluminum-silicon alloy.

Comparative Example 1

The preparation method of aluminum-silicon alloy comprises the following steps:

Step 1. Add 786g of pure Al and 393g of Al-Si alloy preheated to 200°C into the graphite crucible of the resistance furnace, and heat up to 780°C for smelting to obtain primary aluminum liquid;

Step 2: After cooling the primary aluminum liquid to 750°C, add 2.4g of Al-Cu alloy preheated to 200°C to the primary aluminum liquid for smelting and stirring, and after holding for 5 minutes, add 8.7g pure Mg (preheated to 200°C) 20% burning loss) smelting and stirring to obtain alloy liquid;

Step 3: Passing the alloy liquid into high-purity argon gas for blowing for 2 minutes, skimming the slag, and letting it stand for 2 minutes to obtain the alloy liquid after the slag removal;

Step 4: Pour the alloy liquid after slag removal into a mold preheated to 200° C. in advance, and cool it naturally to obtain a casting, which is an aluminum-silicon alloy.

The alloys of Example 1 and Comparative Example 1 were tested. The mechanical tensile curve is shown in Figure 1, and the change curve of thermal conductivity and electrical conductivity is shown in Figure 2. After testing, the thermal conductivity of the as-cast sample modified without Sr (Comparative Example 1) was 145.91W/(m·K), the electrical conductivity was 33.43%IACS, the yield strength was 131.5Mpa, the tensile strength was 217.5Mpa, and the elongation was 3.02. %; the thermal conductivity of the sample (Example 1) with 0.08Sr+T6 heat treatment added is 169.00W/(m·K), the electrical conductivity is 40.22%IACS, which are increased by 15.83% and 20.31% respectively, and the yield strength is 250.46Mpa , the tensile strength is 311.3Mpa, and the elongation is 7.8%, which are increased by 89.0%, 43.13% and 158.28% respectively.

Obviously, the above-mentioned embodiments are only examples for clear description, and are not intended to limit the embodiments. For those of ordinary skill in the art, changes or modifications in other different forms can also be made on the basis of the above description. It is not necessary and cannot be exhaustive to exhaust all embodiments here. However, the obvious changes or changes derived from this are still within the protection scope of the present invention.

Claims (9)

1. A hypoeutectic aluminium silicon alloy, characterised by consisting of 91.3 wt% Al, 8 wt% Si, 0.6 wt% Mg and 0.1 wt% Cu.

2. Method for the preparation of a hypoeutectic aluminium silicon alloy according to claim 1, characterized in that it comprises the following steps:

step one, weighing pure Al, Al-Si alloy, Al-Cu alloy, pure Mg and Al-Sr alloy according to the components, wherein the addition amount of Sr is 0.08 percent of the mass of the alloy liquid;

step two, smelting pure Al, Al-Si alloy, Al-Cu alloy and pure Mg to obtain alloy liquid;

step three, adding Al-Sr alloy into the alloy liquid, smelting and uniformly stirring, and then preserving heat for 15min to obtain modified alloy liquid;

and step four, sequentially carrying out air blowing deslagging, pouring and T6 treatment on the alloy liquid after modification to obtain the hypoeutectic aluminum-silicon alloy.

3. The method of claim 1, wherein the purity of pure Al is not less than 99.8%, the purity of Al-Si alloy is 24.4%, the purity of Al-Cu alloy is 50%, the purity of pure Mg is not less than 99.8%, and the purity of Al-Sr alloy is 10%.

4. The method of producing a hypoeutectic aluminum-silicon alloy according to claim 1, wherein pure Al, Al-Si alloys, Al-Cu alloys and pure Mg are preheated to 200 ℃ before the second step.

5. The method for producing a hypoeutectic aluminum-silicon alloy according to claim 1, wherein the process of step two is: adding pure Al and Al-Si alloy into a resistance furnace, heating to 780 ℃ for smelting and uniformly stirring to obtain primary aluminum liquid, cooling to 750 ℃, adding Al-Cu alloy into the primary aluminum liquid for smelting and uniformly stirring, preserving heat for 5min, adding pure Mg for smelting and uniformly stirring to obtain alloy liquid.

6. The method of producing a hypoeutectic aluminum-silicon alloy according to claim 1, wherein prior to step three, the Al-Sr alloy is preheated to 200 ℃.

7. The method for preparing a hypoeutectic aluminum-silicon alloy according to claim 1, wherein in the fourth step, the process of blowing and deslagging comprises the following steps: and introducing high-purity argon into the alloy liquid after the deterioration, blowing for 2min, skimming, and standing for 2 min.

8. The method for preparing a hypoeutectic aluminum-silicon alloy according to claim 1, wherein in the fourth step, the casting process is as follows: and pouring the alloy liquid subjected to air blowing and deslagging into a mold preheated to 200 ℃, and naturally cooling.

9. The method for preparing a hypoeutectic aluminum-silicon alloy according to claim 1, wherein in the fourth step, the T6 treatment process comprises the following steps: and (3) performing solid solution treatment on the cast at 535 ℃ for 4h, then adding the cast into 25 ℃ water for 5s for water quenching, aging at 170 ℃ for 3h, taking out, and cooling to 25 ℃ in air.

Images