CN112030045B

CN112030045B - Hypoeutectic aluminum-silicon alloy and preparation method thereof

Info

Publication number: CN112030045B
Application number: CN202010861184.6A
Authority: CN
Inventors: 郭劲; 王金国; 管志平; 闫瑞芳; 秦榕; 董中强; 王冠一
Original assignee: Jilin University
Current assignee: Jilin University
Priority date: 2020-08-25
Filing date: 2020-08-25
Publication date: 2022-04-26
Anticipated expiration: 2040-08-25
Also published as: CN112030045A

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 property and the thermal conductivity of the existing hypoeutectic aluminum-silicon alloy is solved. The hypoeutectic aluminum-silicon alloy is prepared by 91.3 wt% of Al, 8 wt% of Si, 0.6 wt% of Mg and 0.1 wt% of Cu, pure Al and Al-Si intermediate alloy are adopted to smelt raw aluminum liquid in a resistance furnace, Al-Cu intermediate alloy and pure Mg are added for alloying, then modification and blowing deslagging are carried out, finally pouring is carried out, and T6 heat treatment is carried out. The hypoeutectic aluminum-silicon alloy has high thermal conductivity, high electrical conductivity and high toughness; the preparation method has simple process and high production efficiency.

Description

Hypoeutectic aluminum-silicon alloy and preparation method thereof

Technical Field

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

Background

Aluminum silicon alloy (Al-Si alloy) is a forged and cast alloy containing aluminum and silicon as main components, generally containing 11 wt% of silicon, and small amounts of copper, iron and nickel added to improve strength, and having a density of about 2.6-2.7g/cm³The thermal conductivity is about 101-126W/(m DEG C.), the Young modulus is 71.0GPa, the impact value is about 7-8.5J, and the fatigue limit is +/-45 MPa.

The Al-Si alloy has light weight, good heat conductivity, certain strength, hardness and corrosion resistance, so that the Al-Si alloy is widely applied to important industries such as aviation, traffic, construction, automobile and the like, is also used for manufacturing low-medium-strength castings with complex shapes, such as cover plates, motor shells, brackets and the like, and is also used as brazing solder.

The Al-Si alloy is a typical eutectic alloy, with no intermediate compounds being produced. However, in hypoeutectic aluminum-silicon alloy, eutectic silicon is in a thick needle shape and seriously cracks a matrix, so that the mechanical properties and the like of the eutectic silicon are reduced, and the requirement of practical application cannot be met. With the development of the 5G technology, the power consumption of signal transmission is greatly increased, and for components such as a base station radiator, the current aluminum-silicon alloy can not meet the requirements of the industry gradually, and higher requirements are put forward on the thermal conductivity.

Disclosure of Invention

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

In order to achieve the purpose, the invention adopts the following technical scheme:

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

The invention also provides a preparation method of the hypoeutectic aluminum-silicon alloy, which 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.

Preferably, the purity of the pure Al is more than or equal to 99.8 percent, the purity of the Al-Si alloy is 24.4 percent, the purity of the Al-Cu alloy is 50 percent, the purity of the pure Mg is more than or equal to 99.8 percent, and the purity of the Al-Sr alloy is 10 percent.

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

Preferably, the process of step two is as follows: 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.

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

Preferably, in the fourth step, the process of blowing to remove slag is as follows: and introducing high-purity argon into the alloy liquid after the deterioration, blowing for 2min, skimming, and standing for 2 min.

Preferably, 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.

Preferably, in the fourth step, the process of T6 processing is as follows: and (3) performing solid solution treatment on the cast product obtained after casting at 535 ℃ for 4h within 5s, putting the cast product into 25 ℃ water for water quenching, aging at 170 ℃ for 3h, taking out, and cooling to 25 ℃ in air.

Compared with the prior art, the invention has the advantages that:

according to the preparation method of the hypoeutectic aluminum-silicon alloy, the hypoeutectic aluminum-silicon alloy is subjected to modification treatment, so that eutectic silicon is refined, mutual staggered connection is reduced, eutectic silicon is broken or even spheroidized through heat treatment, an electronic channel is greatly increased, and the heat conduction and conductivity and the toughness of the aluminum-silicon alloy are improved. Through experimental detection: compared with unmodified aluminum-silicon alloy, the hypoeutectic aluminum-silicon alloy has the advantages that the thermal conductivity and the electric conductivity are respectively improved from 145.91W/(m.K) and 33.43 percent IACS to 169.00W/(m.K) and 40.22 percent IACS; the yield strength, the tensile strength and the elongation are respectively improved from 131.5MPa, 217.5MPa and 3.02 percent to 250.46MPa, 311.3MPa and 7.8 percent.

The preparation method of the hypoeutectic aluminum-silicon alloy has simple process, only needs to strictly prepare the alloy components, can realize the improvement of the alloy performance by T6 treatment in the casting state through one-time modification, simplifies the process flow and improves the production efficiency.

The preparation method of the hypoeutectic aluminum-silicon alloy does not need large equipment in other casting modes, does not need to use noble metal, reduces the production cost and improves the economic benefit.

Drawings

In order to more clearly illustrate the technical solutions in the embodiments of the present invention, the drawings needed to be used in the embodiments will be briefly described below, and it is obvious that the drawings in the following description are only some embodiments of the present invention, and it is obvious for those skilled in the art to obtain other drawings without creative efforts.

FIG. 1 is a graph showing mechanical tensile strength curves of aluminum-silicon alloys prepared in example 1 of the present invention and comparative example 1;

fig. 2 is a graph showing the change in thermal and electrical conductivity of the aluminum-silicon alloy prepared in example 1 of the present invention and the aluminum-silicon alloy prepared in comparative example 1.

Detailed Description

For a further understanding of the invention, preferred embodiments of the invention are described below in conjunction with the detailed description, but it is to be understood that the description is intended to further illustrate the features and advantages of the invention and not to limit the claims to the invention.

The hypoeutectic aluminum-silicon alloy consists of 91.3 wt% of Al, 8 wt% of Si, 0.6 wt% of Mg and 0.1 wt% of Cu.

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

step two, preheating pure Al, Al-Si alloy, Al-Cu alloy and pure Mg to 200 ℃, adding the pure Al and the Al-Si alloy into a resistance furnace, heating to 780 ℃ for smelting and uniformly stirring to obtain raw aluminum liquid, cooling to 750 ℃, adding the Al-Cu alloy into the raw aluminum liquid for smelting and uniformly stirring, keeping the temperature for 5min, adding the pure Mg for smelting and uniformly stirring to obtain alloy liquid.

Step three, preheating the Al-Sr alloy to 200 ℃, adding the Al-Sr alloy into the alloy liquid, smelting and uniformly stirring, and then preserving heat for 15min to obtain modified alloy liquid;

step four, introducing high-purity argon into the alloy liquid after modification, blowing for 2min, skimming (a skimming ladle needs to be coated with a zinc oxide coating and preheated), and standing for 2min to obtain the alloy liquid after blowing and deslagging;

step five, pouring the alloy liquid subjected to air blowing and deslagging into a mold preheated to 200 ℃, and naturally cooling to obtain a casting;

and step six, after solid solution is carried out on the casting for 4 hours at 535 ℃, the casting is put into a water tank at the normal temperature of 25 ℃ for water quenching within 5 seconds, then the casting is taken out after aging is carried out for 3 hours at 170 ℃, and air cooling is carried out until the room temperature is 25 ℃ to obtain the hypoeutectic aluminum-silicon alloy.

In the technical scheme, the purity of pure Al is more than or equal to 99.8 percent, the purity of Al-Si alloy is 24.4 percent, the purity of Al-Cu alloy is 50 percent, the purity of pure Mg is more than or equal to 99.8 percent, and the purity of Al-Sr alloy is 10 percent. Pure Al, Al-Si alloys, Al-Cu alloys, pure Mg and Al-Sr alloys are commercially available. Pure Al, the mass percentage of the chemical components of Fe is less than 0.1002%, Si is less than 0.0030%, Cu is less than 0.003%, Sn is less than 0.001%, Ti is less than 0.001%, and the rest is: and Al. The Al-Si alloy comprises the following chemical components in percentage by mass: 24.4%, Fe < 0.09%, Ti < 0.002%, P < 0.0015%, the balance: and Al. The Al-Cu alloy comprises the following chemical components in percentage by mass: 50%, Ti < 0.05%, V < 0.05%, B < 0.02%, balance: and Al. Pure Mg, the mass percentage of the chemical components of the pure Mg is less than 0.004%, Si is less than 0.005, Cu is less than 0.003, Al is less than 0.006, and the rest is: and Mg. The Al-Sr alloy comprises the following chemical components in percentage by mass Sr: 9.98%, Fe < 0.18%, Ca <0.007, Cu <0.003, balance: and Al.

The terms used in the present invention generally have 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 solution of the present invention, the present invention will be further described in detail with reference to the following embodiments.

In the following examples, various procedures and methods not described in detail are conventional methods well known in the art. Materials, reagents, devices, instruments, apparatuses and the like used in the following examples are commercially available unless otherwise specified.

Example 1

step one, adding 786g of pure Al and 393gAl-Si alloy preheated to 200 ℃ into a graphite crucible of a resistance furnace, heating to 780 ℃ and smelting to obtain primary aluminum liquid;

step two, after the temperature of the raw aluminum liquid is reduced to 750 ℃, adding 2.4g of Al-Cu alloy preheated to 200 ℃ into the raw aluminum liquid for smelting and uniformly stirring, keeping the temperature for 5min, adding 8.7g of pure Mg (20% of burning loss) preheated to 200 ℃ for smelting and uniformly stirring to obtain alloy liquid;

adding 9.6g of Al-Sr alloy (9.98% of Sr, 0.18% of Fe, 0.007% of Ca, 0.003% of Cu and the balance of Al) into a crucible, preheating to 200 ℃, adding the alloy into the alloy liquid, stirring until the alloy liquid is completely melted and uniform, and preserving heat for 15min to obtain the alloy liquid after modification;

step four, introducing high-purity argon into the alloy liquid, blowing for 2min, skimming, and standing for 2min to obtain alloy liquid after deslagging;

step five, pouring the alloy liquid after deslagging into a mold preheated to 200 ℃ in advance, and naturally cooling to obtain a casting;

Comparative example 1

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

step three, introducing high-purity argon into the alloy liquid, blowing for 2min, skimming, and standing for 2min to obtain alloy liquid after deslagging;

and step four, pouring the alloy liquid after deslagging into a mold preheated to 200 ℃ in advance, and naturally cooling to obtain a casting, namely the aluminum-silicon alloy.

The alloys of example 1 and comparative example 1 were examined. The mechanical tensile curve is shown in fig. 1, and the change curve of the thermal conductivity and the electrical conductivity is shown in fig. 2. Through detection, the heat conductivity of the as-cast sample (comparative example 1) without Sr addition is 145.91W/(m.K), the electric conductivity is 33.43 percent IACS, the yield strength is 131.5Mpa, the tensile strength is 217.5Mpa, and the elongation is 3.02 percent; the sample (example 1) with the 0.08Sr + T6 heat treatment had a thermal conductivity of 169.00W/(m · K), an electrical conductivity of 40.22% IACS, an improvement of 15.83% and 20.31% respectively, a yield strength of 250.46Mpa, a tensile strength of 311.3Mpa, and an elongation of 7.8%, an improvement of 89.0%, 43.13% and 158.28% respectively.

It should be understood that the above embodiments are only examples for clarity of illustration and are not intended to limit the embodiments. Other variations and modifications will be apparent to persons skilled in the art in light of the above description. And are neither necessary nor exhaustive of all embodiments. And obvious variations or modifications of the invention may be made without departing from the spirit or scope of the invention.

Claims

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;

step four, performing air blowing deslagging, pouring and T6 treatment on the alloy liquid after modification to obtain hypoeutectic aluminum-silicon alloy;

in the fourth step, the casting process comprises the following steps: pouring the alloy liquid subjected to air blowing and deslagging into a mold preheated to 200 ℃, and naturally cooling;

in the fourth step, the process of T6 processing is as follows: 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.

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

3. The method of claim 2, 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 2, wherein prior to step two, pure Al, Al-Si alloys, Al-Cu alloys and pure Mg are preheated to 200 ℃.

5. The method for producing a hypoeutectic aluminum-silicon alloy according to claim 2, 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 2, 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 2, 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.