CN114214534A

CN114214534A - Modified aluminum alloy and preparation method thereof

Info

Publication number: CN114214534A
Application number: CN202111614261.9A
Authority: CN
Inventors: 方瑛; 答建成
Original assignee: Shanghai Yaohong Technology Co ltd
Current assignee: Shanghai Yaohong Technology Co ltd
Priority date: 2021-12-27
Filing date: 2021-12-27
Publication date: 2022-03-22
Also published as: WO2023125262A1

Abstract

The invention provides a modified aluminum alloy and a preparation method thereof. The preparation method comprises the following steps: step S1, providing an aluminum alloy melt; step S2, providing a modifier; step S3, adding the modifier into the aluminum alloy melt and smelting to obtain a modified aluminum alloy, wherein the modifier is a combination of rare earth aluminum alloy, aluminum strontium intermediate alloy, aluminum titanium or aluminum titanium boron intermediate alloy, or the modifier is a combination of composite rare earth aluminum alloy, aluminum titanium or aluminum titanium boron intermediate alloy, the composite rare earth aluminum alloy contains strontium, titanium or titanium boron and rare earth metal, and the rare earth metal in the rare earth aluminum alloy and the composite rare earth aluminum alloy is any one or more of lanthanum, cerium and yttrium.

Description

Modified aluminum alloy and preparation method thereof

Technical Field

The invention relates to the technical field of alloy materials and preparation, in particular to a modified aluminum alloy and a preparation method thereof.

Background

It is well known that aluminum alloys have many excellent properties and are used in the mechanical manufacturing industry in a very wide range of applications, particularly as the weight of industrial materials (e.g., automotive industry) is reduced, the use of aluminum alloys is increasing.

The cast aluminum alloy is an aluminum alloy obtained by filling a casting mold with molten metal to form parts blanks in various shapes. The high-strength steel has the advantages of low density, high specific strength, good corrosion resistance and casting manufacturability, small limitation of part structural design and the like. However, the mechanical properties such as strength, yield strength and elongation of the cast aluminum alloy commonly used in the market are not high enough, which makes the reduction and thinning of the cast aluminum alloy parts have a bottleneck. The cast aluminum alloy mainly consists of alpha-Al dendrites, eutectic silicon and Mg2Si equilibrium phase. However, under the as-cast condition, the coarse α -Al dendrites and the flaky and massive eutectic silicon seriously deteriorate the mechanical properties, especially the plasticity and the tensile strength, and limit the application in the actual industrial production.

Therefore, it is highly desirable to provide a composite rare earth alloy for modifying aluminum alloy and a method for preparing the same, which can further improve the mechanical properties of cast aluminum alloy and improve the modification and refinement effects.

Disclosure of Invention

In view of this, the present invention provides a modified aluminum alloy capable of further improving the mechanical properties of cast aluminum alloy and improving the modification and refinement effects, and a preparation method thereof.

In order to solve the technical problems, the invention adopts the following technical scheme:

the preparation method of the modified aluminum alloy according to the embodiment of the first aspect of the invention comprises the following steps:

step S1, providing an aluminum alloy melt;

step S2, providing a modifier;

step S3, adding the modifier into the aluminum alloy melt and smelting the mixture in an inert gas atmosphere to obtain modified aluminum alloy,

wherein the modifier is the combination of rare earth aluminum alloy, aluminum strontium intermediate alloy, aluminum titanium or aluminum titanium boron intermediate alloy, or the combination of composite rare earth aluminum alloy, aluminum titanium or aluminum titanium boron intermediate alloy,

the composite rare earth aluminum alloy contains strontium, titanium or titanium boron and rare earth metal,

the rare earth aluminum alloy and the rare earth metal in the composite rare earth aluminum alloy are any one or more of lanthanum, cerium and yttrium.

Further, the preparation of the rare earth aluminum alloy comprises the following steps:

adding the rare earth metal or the intermediate alloy containing the rare earth metal into the aluminum melt under inert atmosphere, heating and stirring until the mixture is completely melted;

after the materials are completely melted, continuously preserving the heat for 10 to 20 minutes to homogenize the materials;

refining the homogenized melt;

and standing for a preset time after refining, and pouring to obtain the rare earth aluminum alloy.

According to some embodiments of the invention, the modifier is a combination of a rare earth aluminum alloy, an aluminum strontium intermediate alloy, an aluminum titanium or an aluminum titanium boron intermediate alloy, wherein the aluminum strontium intermediate alloy is added spaced apart from the aluminum titanium or aluminum titanium boron intermediate alloy, and the rare earth aluminum alloy is added first, or with the first party, or in the aluminum strontium intermediate alloy and the aluminum titanium or aluminum titanium boron intermediate alloy.

Further, the step S3 includes:

step S301, adding the rare earth aluminum alloy into the aluminum alloy melt and smelting to obtain a first uniform mixed melt;

step S302, adding the aluminum-strontium intermediate alloy into the first uniformly mixed melt and continuously smelting to obtain a second uniformly mixed melt;

step S303, adding the aluminum-titanium or aluminum-titanium-boron intermediate alloy into the second uniformly mixed melt and continuously smelting to obtain the modified aluminum alloy.

According to other embodiments of the present invention, the modifier is a combination of a composite rare earth aluminum alloy, aluminum titanium or an aluminum titanium boron intermediate alloy, and the step S3 includes:

step S310, adding the composite rare earth aluminum alloy into the aluminum alloy melt and smelting to obtain a fourth uniform mixed melt;

step S320, adding the aluminum-titanium or aluminum-titanium-boron intermediate alloy into the fourth uniformly mixed melt and continuously smelting to obtain the modified aluminum alloy.

Further, the preparation of the composite rare earth aluminum alloy comprises the following steps:

step S311, providing an aluminum alloy melt;

step S312, providing an aluminum-strontium intermediate alloy, an aluminum-titanium or aluminum-titanium-boron intermediate alloy and a rare earth aluminum alloy, wherein the rare earth metal in the rare earth aluminum alloy is one or more selected from lanthanum, cerium and yttrium;

and step S313, adding the aluminum-strontium intermediate alloy, the aluminum-titanium or the aluminum-titanium-boron intermediate alloy into the aluminum alloy melt in an inert gas atmosphere, and smelting to obtain the modified aluminum alloy.

Further, in step S313, the al-sr intermediate alloy and the al-ti or al-ti-b intermediate alloy are added separately, and the rare earth aluminum alloy is added before the al-sr intermediate alloy and the al-ti or al-ti-b intermediate alloy, or together with the first addition, or added in the gap between the al-sr intermediate alloy and the al-ti or al-ti-b intermediate alloy.

Further, in step S313, the rare earth aluminum alloy, the aluminum-strontium intermediate alloy, the aluminum-titanium or the aluminum-titanium-boron intermediate alloy are sequentially added into the aluminum melt at intervals.

Further, the modifier accounts for 0.4-0.6 wt% of the total amount of the modified aluminum alloy, and the rare earth metal: strontium: the mass ratio of the total amount of titanium or titanium boron is 1 (0.1-1.2): (0.1-1.2).

Further, refining the modifier prior to adding it to the aluminum melt, the refining comprising:

blowing the refining agent through inert gas and keeping for 3-10 minutes, adding deslagging agent and stirring for 5-10 minutes, and removing the surface scum.

Furthermore, the addition amount of the refining agent accounts for 0.1-0.3% of the mass of the added melt, and the addition amount of the slag removing agent accounts for 0.1-0.3% of the mass of the added melt;

the refining agent comprises the following components in percentage by mass:

10-15 parts of potassium chloride, 15-25 parts of sodium chloride, 8-15 parts of calcium fluoride, 15-25 parts of sodium carbonate, 8-12 parts of sodium sulfate, 10-20 parts of sodium fluoroaluminate and 8-12 parts of hexachloroethane;

the slag remover comprises the following components in percentage by mass:

25-30 parts of sodium chloride, 25-30 parts of potassium chloride, 5-10 parts of sodium carbonate, 5-10 parts of sodium sulfate, 1-5 parts of sodium fluoroaluminate, 5-10 parts of sodium fluosilicate, 5-10 parts of calcium fluoride, 1-5 parts of potassium nitrate and 5-10 parts of potassium fluosilicate.

Further, the density of the melt was measured before and during the refining, when the density of the melt was less than 2.65g/cm³If so, carrying out the refining treatment;

when the melt density is more than or equal to 2.65g/cm³I.e., not performing the refining process or terminating the refining process.

The modified aluminum alloy according to the second aspect of the present invention is produced by the production method according to any one of the above embodiments.

The technical scheme of the invention at least has one of the following beneficial effects:

according to the preparation method of the modified aluminum alloy, the rare earth metal is introduced, so that the mutual poisoning effect between the modifier and the refiner is greatly overcome, the addition amounts of the modifier and the refiner can be increased, and the modification and refinement effects can be improved;

furthermore, the invention enables the aluminum-strontium intermediate alloy (i.e. modifier) and the aluminum-titanium alloy or the aluminum-titanium-boron alloy (i.e. refiner) to be added at intervals by reasonably adjusting the process, and the rare earth metal is added before the latter is added, so that the mutual poisoning between the modifier and the refiner can be further effectively avoided, and the modification and refinement effects can be further improved;

further, the rare earth aluminum alloy, the aluminum-strontium intermediate alloy, the aluminum-titanium alloy or the aluminum-titanium-boron alloy are alloyed in advance to obtain the composite rare earth aluminum alloy, and the aluminum alloy is modified by the composite rare earth aluminum alloy, so that the modification effect is further improved;

furthermore, the melt in each stage is refined to remove impurities, so that the mechanical property of the final aluminum alloy product is further improved.

Drawings

FIG. 1 is a metallographic structure image of an aluminum alloy before modification;

FIG. 2 is a metallographic structure image of a modified aluminum alloy obtained in example 1 of the present invention.

Detailed Description

In order to make the objects, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions of the present invention will be clearly and completely described below with reference to the embodiments of the present invention. It is to be understood that the embodiments described are only a few embodiments of the present invention, and not all embodiments. All other embodiments, which can be derived by a person skilled in the art from the described embodiments of the invention, are within the scope of the invention.

Unless defined otherwise, technical or scientific terms used herein shall have the ordinary meaning as understood by one of ordinary skill in the art to which this invention belongs. The use of "first," "second," and similar terms in the present application do not denote any order, quantity, or importance, but rather the terms are used to distinguish one element from another. Also, the use of the terms "a" or "an" and the like do not denote a limitation of quantity, but rather denote the presence of at least one.

The method for producing the modified aluminum alloy according to the embodiment of the invention will be described first in detail.

The preparation method of the modified aluminum alloy comprises the following steps:

step S1, providing an aluminum alloy melt.

That is, an aluminum alloy melt is first prepared.

Here, it should be noted that a commercially available high-purity aluminum alloy ingot may be directly heated and melted to prepare an aluminum alloy melt, or the aluminum alloy ingot may be further purified. The purification treatment may, for example, comprise the following steps:

step S11, providing an aluminum alloy ingot;

step S12, removing an oxide scale layer on the surface of the aluminum alloy ingot;

step S13, cleaning and drying the aluminum alloy ingot with the oxide scale layer removed;

step S14, smelting the dried aluminum alloy ingot to obtain an initial melt;

and step S15, refining the initial melt to obtain the aluminum alloy melt.

That is, for the aluminum alloy ingot, the scale layer on the surface thereof is first removed, thereafter, cleaning is performed to remove surface floating chips, and after drying, melting is performed, and the melt is refined. Details regarding the specific refining process will be described later.

After the above purification treatment, undesired impurities such as Fe, oxides, etc. can be removed therefrom. Is favorable for further improving the modification and refinement of the rare earth alloy.

It should be noted that, regarding Fe and its oxide, it can be removed by adding manganese or aluminum-manganese alloy to form surface scum, for example.

The modified matrix, i.e., the aluminum alloy melt, may be, for example, an aluminum-magnesium alloy, an aluminum-silicon-magnesium alloy, or the like, and the present invention is not particularly limited thereto.

Step S2, providing a modifier.

That is, there are two embodiments as follows:

the first implementation mode comprises the following steps:

the modifier is a combination of rare earth aluminum alloy, aluminum-strontium intermediate alloy, aluminum-titanium or aluminum-titanium-boron intermediate alloy.

Wherein the aluminum-strontium intermediate alloy is a modifier, and the aluminum-titanium intermediate alloy or the aluminum-titanium-boron intermediate alloy is a refiner. That is, conventional modifiers and refiners may be used.

Further, the modifier and/or the refiner can be made of commercially available materials, or can be made by weighing the corresponding metals strontium, titanium & boron, respectively, and melting the metals in an aluminum melt to form a uniform alloy.

In addition, rare earth aluminum alloys have been further introduced in addition to conventional modifiers and refiners to overcome the limitations of mechanical properties due to the "poisoning" reaction between the modifier and the refiner. As the rare earth metal in the rare earth aluminum alloy, a group IIIB element having an electronic structure intervening therebetween may be selected in consideration of strontium in the modifier and titanium and boron in the refiner. Considering stability, resources and the like, it is preferable to use yttrium, one or more of lanthanum and cerium in lanthanide metals. The rare earth aluminum alloy may be one or more of commercially available Al-10Ce, Al-20La, Al-10La and Al-20Y, Al-10Y.

In addition, the rare earth aluminum alloy can be prepared by self, and can be prepared by the following method:

adding the rare earth metal or the intermediate alloy containing the rare earth metal into the aluminum melt under inert atmosphere, and stirring the mixture to be completely molten while heating the mixture;

refining the homogenized melt;

The aluminum melt may be a commercially available high-purity aluminum ingot, and the corresponding treatment is performed by referring to the purification treatment of the aluminum alloy ingot, which is not described herein again.

In addition, for the commercial aluminum strontium intermediate alloy, aluminum titanium intermediate alloy or aluminum titanium boron intermediate alloy, rare earth aluminum alloy, respectively, the descaling, ultrasonic cleaning and refining treatment can be sequentially carried out. Thereby, the undesirable impurities and oxides can be further removed, and the refining and modification effects of the composite rare earth alloy as a product can be improved.

The second embodiment:

the modifier is a combination of a composite rare earth aluminum alloy, aluminum titanium or an aluminum titanium boron intermediate alloy.

The rare earth aluminum alloy can be prepared by smelting and refining the rare earth aluminum alloy, the modifier, the refiner and the aluminum melt.

For example, the preparation of the composite rare earth aluminum alloy may include:

step S311, providing an aluminum melt;

and step S313, adding the aluminum-strontium intermediate alloy, the aluminum-titanium or the aluminum-titanium-boron intermediate alloy into the aluminum melt in an inert gas atmosphere, and smelting to obtain the composite rare earth alloy for modifying the aluminum alloy.

In step S313, the al-sr intermediate alloy and the al-ti or al-ti-b intermediate alloy are added at a distance, and the rare earth aluminum alloy is added before the al-sr intermediate alloy and the al-ti or al-ti-b intermediate alloy, or together with the first addition, or in a gap between the al-sr intermediate alloy and the al-ti or al-ti-b intermediate alloy.

Preferably, in step S313, the rare earth aluminum alloy, the aluminum strontium intermediate alloy, the aluminum titanium or the aluminum titanium boron intermediate alloy are sequentially added into the aluminum melt at intervals.

And step S3, adding the modifier into the aluminum alloy melt and smelting in an inert gas atmosphere to obtain the modified aluminum alloy.

That is, after preparing the aluminum alloy melt and the modifier, adding the modifier into the aluminum alloy melt under the inert gas atmosphere for further smelting to obtain the modified aluminum alloy.

According to the preparation method of the modified aluminum alloy, the rare earth metal is introduced into the modifier, so that the mutual poisoning effect between the modifier and the refiner is greatly overcome, the addition amounts of the modifier and the refiner can be increased, and the modification and refinement effects can be improved.

In addition, the inventors of the present invention have repeatedly studied and found that by adjusting the order of adding the modifying agent, the refining agent, and the rare earth aluminum alloy, the mutual poisoning between the modifying agent and the refining agent can be further effectively avoided, which is advantageous for further improving the modifying and refining effects.

The two combined modifiers were melted as follows.

Aiming at the combination that the modifier is rare earth aluminum alloy, aluminum-strontium intermediate alloy, aluminum-titanium or aluminum-titanium-boron intermediate alloy:

specifically, each of the rare earth aluminum alloy, the aluminum strontium intermediate alloy, the aluminum titanium or aluminum titanium boron intermediate alloy, and the pretreatment thereof may refer to the above step S2.

In the case of this combination, wherein the aluminum strontium master alloy is added spaced apart from the aluminum titanium or aluminum titanium boron master alloy, the rare earth aluminum alloy is added first, or with the first addition, or in the aluminum strontium master alloy and the aluminum titanium or aluminum titanium boron master alloy.

Further preferably, the step S3 may specifically include:

That is, by adding the rare earth aluminum alloy and smelting, and then sequentially adding the aluminum-strontium intermediate alloy serving as the modifier and the aluminum-titanium intermediate alloy or the aluminum-titanium-boron intermediate alloy serving as the refiner at intervals on the basis, the poisoning effect of strontium and boron can be better solved, and the modified aluminum alloy which is more refined and uniform and has higher mechanical property can be obtained.

In addition, for the combination of the modifier being a composite rare earth aluminum alloy, aluminum titanium or an aluminum titanium boron intermediate alloy, the step S3 includes:

That is, when the rare earth aluminum alloy, the modifier, the refiner and the aluminum are melted in advance to prepare the composite rare earth aluminum alloy, the rare earth aluminum alloy can be added to the aluminum melt at one time for preparation. Of course, considering that abnormal growth of crystal grains is likely to occur in the case of high-temperature melting, which is not favorable for improving the mechanical properties, it is preferable that a refiner, i.e., an aluminum-titanium intermediate alloy or an aluminum-titanium-boron intermediate alloy, be further added to control the grain growth in the case where the composite rare earth aluminum alloy is completely melted and uniformly mixed with the aluminum alloy.

The addition amount of the modifier is designed according to the use requirement and the content of each effective component in the intermediate alloy. As an example, for example, in the case of incorporation by a composite rare earth alloy in which the rare earth element contained is strontium to titanium or titanium boron in a mass ratio of 1 (0.05 to 1.2) to (0.0001 to 1), the modifier preferably accounts for 0.4 to 0.6 wt% of the total amount of the modified aluminum alloy.

Further, the refining in any one of the above steps, i.e., the refining in the purification process of the aluminum melt, the refining in the preparation process of the rare earth aluminum alloy, and the refining of each melt in the composite rare earth aluminum alloy, can be performed in the following manner:

Furthermore, the adding amount of the refining agent accounts for 0.1-0.3% of the mass of the added melt, and the adding amount of the slag removing agent accounts for 0.1-0.3% of the mass of the added melt;

the refining agent comprises the following components in percentage by mass:

the slag remover comprises the following components in percentage by mass:

Further, the density of the melt was measured when the density of the melt was less than 2.65g/cm³If so, carrying out the refining treatment; when the melt density is more than or equal to 2.65g/cm³I.e., not performing the refining process or terminating the refining process.

The production process according to the present invention is further illustrated in detail by the following specific examples.

Example 1

Aluminum alloy: adopts aluminum silicon magnesium alloy (A356) (purchased from Shandong Chuanfeng Shanxi aluminum)

High purity aluminum ingot (purchased from medium aluminum group, composition: Al (99.99%), Fe < 0.1%, impurity < 0.05%)

Refining agent:

the components: 15 parts of potassium chloride, 20 parts of sodium chloride, 210 parts of CaF, 320 parts of Na2CO, 410 parts of Na2SO, 615 parts of Na3AlF and 610 parts of C2 Cl.

Deslagging agent:

the components: 25 parts of sodium chloride, 25 parts of potassium chloride, 5 parts of sodium carbonate, 5 parts of sodium sulfate, 5 parts of sodium fluoroaluminate, 10 parts of sodium fluosilicate, 10 parts of calcium fluoride, 5 parts of potassium nitrate and 10 parts of potassium fluosilicate.

1) Preparation of an aluminium alloy melt

Melting: firstly, preheated Al-Si-Mg alloy A356 is added into a smelting furnace with a temperature rise in advance, and is heated and melted into molten aluminum within the range of 760 ℃.

Degassing and deslagging: after melting into molten aluminum, nitrogen (or argon) was introduced, and then a refining agent (0.3 wt% refining agent) was blown into the molten aluminum, with the period of 15 minutes.

Standing: and (4) standing the molten aluminum in the step S3 for 10 minutes, controlling the temperature to be 760 ℃, and fishing out slag impurities on the surface layer of the molten aluminum.

During the period, the chemical composition is measured and the hydrogen amount is estimated by taking a sample of the aluminum water which is standing:

estimating the hydrogen content by a density method, wherein the density requirement is as follows: greater than or equal to 2.65g/cm 3. The greater the density (closer to 2.7g/cm3), the lower the hydrogen content therein.

2) Preparation of high-purity rare earth aluminum alloy

2.1) preparation of high-purity aluminum melt

Pretreatment: and (4) cleaning the oxide skin and the surface layer on the surface of the high-purity aluminum ingot by using a grinding wheel machine.

Ultrasonic cleaning: and (4) putting the pretreated high-purity aluminum ingot into a cleaning agent for ultrasonic treatment.

Drying: and (3) placing the high-purity aluminum ingot subjected to ultrasonic cleaning into a baking oven furnace, and baking for 30-60 minutes at the temperature of 60-100 ℃.

Smelting: and putting the dried high-purity aluminum into a preheated crucible, and heating and melting at 760 and 800 ℃.

Refining treatment: and refining after the high-purity aluminum is melted. Specifically, the method comprises the following steps: and refining the molten high-purity aluminum by using an Ar + graphite automatic degassing stirring rod. Blowing Ar into the melt for refining at 740-760 ℃ for 5-10 min, wherein the refining dose is 0.1-0.3%, and keeping the temperature for 3-5 min. And standing for 10-20 minutes, and adding 0.1-0.3% of deslagging agent into the mixture to uniformly disperse the deslagging agent, and removing the surface scum.

Standing: standing for 8-15 minutes at 740-760 ℃ after slagging off.

2.2) smelting and processing of rare earth aluminum alloy: adjusting the temperature of the high-purity aluminum obtained in the step 1) to 780-820 ℃, heating to completely melt the high-purity aluminum, and adding a rare earth aluminum lanthanum alloy (purchased from Baotou rare earth research institute, components: al-10La, Fe < 0.05). Heating at 780-820 ℃ under the protection of argon atmosphere to completely melt the alloy.

Stirring and heat preservation: stirring the melted melt for 3-5 min to homogenize the melt, and maintaining the temperature of the melt at 760-780 ℃ for 10-20 min.

Refining treatment: the whole process is carried out under the protection of argon atmosphere, and refining treatment is carried out after the rare earth aluminum lanthanum alloy is melted. And introducing an Ar + graphite automatic degassing stirring rod to refine the molten graphite. Blowing Ar into the molten aluminum for refining at 760-780 ℃ for 5-10 minutes, wherein the blowing amount of the melt is 0.1-0.3%, and the melt is kept for 3-5 minutes, and no boiling bubbles can exist on the upper surface of the molten aluminum in the refining process. Removing scum on the surface of the melt: and (3) putting 0.1-0.3% of deslagging agent into the mixture for 15-20 minutes, uniformly dispersing, and removing the scum on the surface.

Standing: standing for 10-15 minutes at 720-730 ℃ after slagging off.

Casting: and (3) quickly casting the melt in a mould to ensure that all components are uniform. The process adopts full water cooling to cool the device.

3) Refining treatment of Al-Sr intermediate alloy and Al-Ti-B intermediate alloy

3.1) aluminum-strontium master alloy: purchased from nan tong ang shen metals materials ltd, ingredients: al-10Sr, Fe < 0.05.

Pretreatment: and (3) cleaning the oxide skin and the surface layer of the aluminum-strontium intermediate alloy by using a grinding wheel machine.

Ultrasonic cleaning: and (3) putting the pretreated aluminum-strontium intermediate alloy into an ultrasonic cleaning tank for ultrasonic treatment.

Drying: and (3) putting the cleaned aluminum-strontium intermediate alloy into an oven furnace, and baking for 30-60 minutes at the temperature of 60-100 ℃.

Smelting: the aluminum-strontium intermediate alloy is put into a preheated crucible to be melted at 760-780 ℃.

Refining treatment: and refining after the aluminum-strontium intermediate alloy is melted. And introducing an Ar + graphite automatic degassing stirring rod to refine the molten high-purity aluminum. Blowing Ar into the molten aluminum for refining at the temperature of 730-750 ℃ for 5-10 minutes, wherein the blowing refining dose is 0.1-0.3 percent of the melt, and keeping the melt for 3-5 minutes, and no boiling bubbles can be formed on the upper surface of the molten aluminum in the refining process.

Removing surface scum: and (3) putting 0.1-0.3% of deslagging agent into the mixture for 15-20 minutes, uniformly dispersing, and removing the scum on the surface.

Standing: standing for 8-15 minutes at 740-760 ℃ after slagging off.

3.2) aluminum titanium boron intermediate alloy: from Nantong Angshen Metal materials Co., Ltd (composition and content: Ti: 5%, B: 1%, remainder: Al)

The aluminum titanium boron intermediate alloy as the refiner was treated in the same manner as described above.

4) Preparation of composite rare earth alloy

Respectively preparing an aluminum melt, a rare earth aluminum alloy, an aluminum strontium intermediate alloy and an aluminum titanium boron intermediate alloy through the steps of 1) to 3), and then carrying out mixed smelting on the aluminum melt, the rare earth aluminum alloy, the aluminum strontium intermediate alloy and the aluminum titanium boron intermediate alloy to obtain the composite rare earth alloy serving as a product.

In this embodiment, as the order of addition, the rare earth aluminum alloy is added to the aluminum melt, followed by the aluminum-strontium alloy, and finally the aluminum-titanium alloy. The method comprises the following specific steps:

step 1, batching: weighing the obtained high-purity aluminum, the aluminum-titanium-boron intermediate alloy, the aluminum-strontium intermediate alloy and the rare earth aluminum alloy according to the required mass percentage, and then preheating.

Based on 100 parts of total weight, high-purity aluminum: 4.8 parts of aluminum-titanium-boron intermediate alloy: 0.2 part of aluminum-strontium intermediate alloy: 60 parts of rare earth aluminum alloy: 35 parts of (A).

Step 2, adding and melting rare earth aluminum alloy: for the aluminum melt, firstly heating the rare earth aluminum alloy to 780-820 ℃ to soften the aluminum alloy before melting, then controlling the overall temperature of the aluminum melt to 760-780 ℃, and adding the rare earth aluminum alloy into the aluminum melt for heat preservation.

The whole process adopts argon atmosphere protection to melt rare earth aluminum alloy.

And 3, after the rare earth aluminum alloy is completely melted, controlling the temperature to be 750-770 ℃, and stirring for 5-10 minutes.

The whole process adopts argon atmosphere for protection, and the stirring rod adopts graphite material and is preheated to 400-plus-500 ℃ before stirring.

That is, after the rare earth aluminum alloy is completely melted, the temperature is slightly lowered, and it is possible to prevent subsequent grain coarsening and the like due to overheating.

And 4, performing heat preservation treatment on the melted melt at 740-760 ℃ for 5-20 minutes. In this stage, an alloying reaction occurs.

And 5, refining: after the heat preservation is finished, refining, degassing and deslagging are carried out. Blowing 0.3% of refining agent into the melt through argon, and controlling the ventilation time to be 3-8 minutes; then, the mixture was further added to 0.2% of a slag remover, stirred for 5 minutes, allowed to stand and removed of slag and impurities on the surface layer of the melt. The whole process adopts argon atmosphere protection.

The aluminum melt was sampled before and during refining and its density was measured to estimate the hydrogen content. The measurement method used a density method (comparing with the theoretical value of aluminum of 2.70g/cm 3), and the closer the measured sample is to 2.7g/cm3, the lower the internal hydrogen content of aluminum. Normally, the concentration of the active carbon can not reach 2.7g/cm 3; the density test of the sample is about equal to 2.65g/cm3, namely, the vacuum treatment is needed in the process of estimating the hydrogen content, and if the hydrogen content is not qualified, the refining is further carried out, namely, the refining agent is repeatedly added, and the deslagging agent is refined again.

Step 6, standing: and standing the melt which is added with the rare earth aluminum alloy and refined for 3-5 minutes, and controlling the temperature at 740-760 ℃.

And 7, adding and melting an aluminum-strontium intermediate alloy: and (3) adding the refined aluminum-strontium intermediate alloy into the melt obtained in the step (6), and controlling the temperature to be 780-820 ℃ so that the aluminum-strontium intermediate alloy is completely melted. The whole process adopts argon atmosphere protection to melt the aluminum-strontium intermediate alloy.

And 8, after the aluminum-strontium intermediate alloy is melted, controlling the temperature to be 740-760 ℃, and stirring for 3-8 minutes to realize homogenization. The whole process adopts argon atmosphere for protection, the stirring rod adopts graphite material, and the stirring rod is preheated to 400-plus-500 ℃ before stirring.

And 9, performing heat preservation treatment at 725-750 ℃. The heat preservation time is controlled to be 15-30 minutes.

Step 10, refining, degassing and deslagging: after the heat preservation of the melt is finished, blowing argon gas into the melt, and then blowing 0.3% of refining agent into the aluminum-rare earth composite melt, wherein the ventilation time is controlled to be 5-10 minutes; adding 0.2% of slag skimming agent into the aluminum melt, stirring for 5 minutes and fishing out slag and impurities on the surface layer of the aluminum-rare earth composite melt. The whole process adopts argon atmosphere protection.

The aluminum melt was sampled before and during refining to determine the hydrogen content. (hydrogen content required: 2.65g/cm or more³(ii) a ) And (3) vacuumizing in the hydrogen measuring process, and further refining if the hydrogen content is unqualified, namely, repeatedly adding a refining agent and a deslagging agent for refining again.

Step 11, adding an aluminum-titanium-boron intermediate alloy: and (3) adding an aluminum-titanium-boron intermediate alloy into the melt treated in the step (10), heating to completely melt the aluminum-titanium-boron intermediate alloy, and uniformly stirring for 3-5 minutes to homogenize the aluminum-titanium-boron intermediate alloy.

Step 12, heat preservation: after stirring, the melt is kept at the temperature of 715-725 ℃ for 8-12 minutes.

Step 13, refining, degassing and deslagging: after the heat preservation of the melt is finished, blowing argon gas into the melt, and then blowing 0.3% of refining agent into the aluminum-rare earth composite melt, wherein the ventilation time is controlled to be 5-10 minutes; adding 0.2% of slag skimming agent into the aluminum melt, stirring for 5 minutes and fishing out slag and impurities on the surface layer of the aluminum-rare earth composite melt. The whole process adopts argon atmosphere protection.

The aluminum melt was sampled before and during refining to determine the hydrogen content. (hydrogen content required: 2.65g/cm or more³(ii) a ) And (3) vacuumizing in the hydrogen measuring process, and if the hydrogen content is unqualified, further refining, namely repeatedly adding a refining agent and a deslagging agent, and refining again until the hydrogen content is qualified.

Step 14, casting: the mold was preheated at 300 ℃ to 400 ℃. And (3) controlling the temperature of the composite rare earth alloy melt obtained in the step (13) to be 715-725 ℃ for casting.

Preferably, during casting, oxides on the surface layer of the composite rare earth alloy melt are filtered by a filter screen of glass fibers; and filtering the surface layer of the aluminum-rare earth composite melt before each casting, and then casting.

Preferably, the cooling control of the cast mould is that the aluminum rare earth composite melt cast into the mould is cooled in a water cooling mode, the solidification speed of the aluminum melt is controlled at 50-100 ℃/s in the cooling process, and the solidification mode is sequentially solidified.

The composite rare earth aluminum alloy obtained in the above embodiment, wherein the rare earth metal: strontium: the mass ratio of the titanium or the titanium boron is 1 (0.1-1.2): (0.1-1.2). That is, the content of the modifier and the refiner can be increased and the modifier and the refiner can sufficiently function.

5) Preparation of modified aluminum alloy

In this embodiment, the modifier is a combination of a composite rare earth aluminum alloy and a refiner. Specifically, the production of the composite rare earth aluminum alloy refers to the above 4).

The aluminum titanium boron intermediate alloy as the refiner refers to 3.2) above.

After obtaining the composite rare earth aluminum alloy and the refined refiner respectively, mixing the aluminum alloy: compounding rare earth aluminum alloy: the mass ratio of the refiner is 99.4: 0.4: 0.2 of the above aluminum-silicon-magnesium alloy, composite rare earth aluminum alloy, and aluminum-titanium-boron intermediate alloy.

Among these, it is preferable that the aluminum alloy is refined after removing the oxide layer.

Thereafter, melting was performed as follows.

Mixing: according to the proportion, when the temperature of the aluminum-silicon-magnesium alloy melt after the treatment of the 1) is controlled to be 740 +/-5 ℃, the composite rare earth aluminum alloy obtained in the 4) is firstly added.

Stirring: stirring the melt which is added with the composite rare earth aluminum alloy and melted by a graphite stirrer, wherein uniform stirring is required in the stirring process, and the stirring is continuously carried out for 8 minutes;

and (3) heat preservation: after stirring, controlling the temperature at 735 ℃ and keeping the temperature for 20 minutes;

refining: after the heat preservation is finished, argon is introduced, then a slag remover is blown into the molten aluminum, and the ventilation time is controlled to be 15 minutes;

adding a refiner: adding 0.2% of aluminum-titanium-boron intermediate alloy into refined molten aluminum, and continuously refining after the intermediate alloy is melted and stirred;

and (3) heat preservation and standing: after refining is finished, after the molten aluminum flows into a heat preservation pool, when the temperature is controlled to be 710 +/-3 ℃, standing for 10 +/-2 minutes, and removing slag and impurities on the surface layer of the molten aluminum;

casting: and when the preheating mould is at the temperature of 250-400 ℃, casting the refined modified aluminum alloy with the temperature controlled at 700 +/-5 into the mould, and cooling to obtain the modified aluminum alloy.

Fig. 1 shows the metallographic structure of an aluminum alloy before modification, and fig. 2 shows the metallographic structure after modification. As can be seen from fig. 1 and 2, the metallographic structure of the aluminum alloy before modification (fig. 1) shows that the coarse primary α -Al phase is in the form of dendrite structure, and the diameter, length, and dendrite spacing of the secondary dendrites are relatively large. The metallographic structure of the improved aluminum alloy has a large amount of rosette alpha-Al phase and round spherical alpha-Al phase, the primary alpha-Al phase is obviously refined, and the number of dendritic crystals is reduced. That is, after modification, the crystal grains are sufficiently refined and the microstructure is uniform.

In addition, the mechanical properties of the a356 aluminum alloy after modification were evaluated. The evaluation results (described as example 1) are shown in table 1 below. For comparison, the results of the tests on the unmodified A356 aluminum alloy (before modification) are also shown.

Meanwhile, except for using the aluminum-strontium alloy as the modifier (referred to as comparative example 1) instead of the composite rare earth aluminum alloy of the present example, the aluminum-strontium alloy is directly prepared by using the rare earth aluminum alloy (referred to as comparative example 1, 2), and the aluminum-strontium alloy is referred to as comparative example 2), and the test results of the modified a356 aluminum alloy are also shown.

TABLE 1A 356 aluminum alloy and modified mechanical Property test results

Mechanical Properties	Before modification	Comparative example 1	Comparative example 2	Example 1
					Tensile strength (MPa)	130±3.5	180±5.1	175±5.5	220±5
Yield strength (MPa)	65±5.5	82±4.2	80±4.2	108±6
					Elongation (%)	3±0.25	6.6±0.45	8.6±0.35	20±0.6

As can be seen from table 1, by using the composite rare earth aluminum alloy of the present example, the elongation, yield strength, and tensile strength were greatly improved, and the comprehensive mechanical properties were greatly improved. Further, the overall mechanical properties can be further improved as compared with those of conventional modifiers or modifications using only rare earth alloys.

Example 2

In this example, the same as example 1 was conducted except that an aluminum-strontium master alloy was added together with a rare earth aluminum alloy in the preparation of a composite rare earth aluminum alloy, as compared with example 1.

In the following, only the parts involved in the preparation of the composite rare earth alloy are described as follows:

4) preparation of composite rare earth alloy

Taking 100 parts as an example, high-purity aluminum: 4.8 parts of aluminum-titanium-boron intermediate alloy: 0.2 part of aluminum-strontium intermediate alloy: 60 parts of rare earth aluminum alloy: 35 portions of

Step 2, adding and melting rare earth aluminum alloy and aluminum-strontium intermediate alloy: and (3) controlling the temperature of the aluminum melt to be 760-780 ℃, and adding the rare earth alloy material and the aluminum-strontium intermediate alloy into the aluminum melt.

The whole process adopts argon atmosphere protection, and the rare earth aluminum alloy is melted when the temperature is controlled to be 780-820 ℃.

And 3, after the rare earth aluminum alloy and aluminum-strontium intermediate alloy is completely melted, controlling the temperature to be 750-770 ℃, and stirring for 5-10 minutes. The whole process adopts argon atmosphere for protection, the stirring rod adopts graphite material, and the stirring rod is preheated to 400-plus-500 ℃ before stirring.

And 4, performing heat preservation treatment on the melted melt at 740-760 ℃ for 5-20 minutes.

The aluminum melt was sampled before and during refining to estimate the hydrogen content. (required melt density: 2.65g/cm or more)³. ) And (3) vacuumizing in the hydrogen measuring process, and further refining if the hydrogen content is unqualified, namely, repeatedly adding a refining agent and a deslagging agent for refining again.

Thereafter, an aluminum-titanium-boron intermediate alloy is further added to the alloy and melted. The specific steps can be referred to in example 1, and detailed description thereof is omitted here.

In addition, the experimental result shows that the composite rare earth aluminum alloy obtained according to the embodiment can also effectively improve the mechanical strength of the aluminum alloy and realize better refining and modification effects. The detailed data thereof is omitted here.

Example 3

In this example, the same as example 1, except that instead of using a composite rare earth aluminum alloy, a rare earth aluminum alloy, an aluminum strontium alloy, and an aluminum titanium boron alloy were sequentially added at intervals.

Hereinafter, only the differences involved in the preparation of the modified aluminum alloy of the above-described step 5) will be described.

In this embodiment, the modifier is a combination of a rare earth aluminum alloy, an aluminum strontium alloy, and an aluminum titanium boron alloy. Specifically, the sources and treatments of rare earth aluminum alloys, aluminum strontium alloys, and aluminum titanium boron alloys are referenced above in example 1.

After obtaining the rare earth aluminum alloy and the refined refiner respectively, mixing the following components in parts by weight: rare earth aluminum alloy: aluminum-strontium master alloy: the mass ratio of the aluminum-titanium-boron alloy is (99.4-99.6): (0.3-0.5): (0.1-0.3) to (0.1-0.3) preparing the above Al-Si-Mg alloy, rare earth aluminum alloy, Al-Sr intermediate alloy, and Al-Ti-B intermediate alloy.

Thereafter, melting was performed as follows.

Mixing: according to the proportion, when the temperature is controlled to be 740 +/-5 ℃ in the treated aluminum-silicon-magnesium alloy melt, the rare earth aluminum alloy is firstly added.

adding an aluminum-strontium intermediate alloy: adding the aluminum-strontium intermediate alloy after refining, and refining and preserving heat (the refining and preserving heat steps are referred to above);

adding a refiner: adding 0.2% of aluminum-titanium-boron intermediate alloy into refined molten aluminum, melting and stirring the molten aluminum, and continuously refining and preserving heat (the refining and preserving heat steps are referred to above);

removing slag: after the heat preservation is finished, standing for 10 +/-2 minutes, and removing slag and impurities on the surface layer of the molten aluminum;

casting: and when the preheating mould is at the temperature of 250-400 ℃, casting the refined modified aluminum alloy with the temperature controlled at 700 +/-5 into the mould, and cooling to obtain the modified aluminum alloy. In addition, the experimental result shows that the modified aluminum alloy obtained according to the embodiment can also effectively improve the mechanical strength of the aluminum alloy and realize better refining and modification effects. The detailed data thereof is omitted here.

While the foregoing is directed to the preferred embodiment of the present invention, it will be understood by those skilled in the art that various changes and modifications may be made without departing from the spirit and scope of the invention as defined in the appended claims.

Claims

1. The preparation method of the modified aluminum alloy is characterized by comprising the following steps:

step S1, providing an aluminum alloy melt;

step S2, providing a modifier;

2. The method according to claim 1, wherein the preparation of the rare earth aluminum alloy comprises the steps of:

refining the homogenized melt;

3. The method of claim 2, wherein the modifier is a combination of a rare earth aluminum alloy, an aluminum strontium intermediate alloy, an aluminum titanium or an aluminum titanium boron intermediate alloy, wherein the aluminum strontium intermediate alloy is added spaced apart from the aluminum titanium or the aluminum titanium boron intermediate alloy, and the rare earth aluminum alloy is added first, or together with the first addition, or in the gap between the aluminum strontium intermediate alloy and the aluminum titanium or the aluminum titanium boron intermediate alloy.

4. The method for preparing a composite material according to claim 3, wherein the step S3 includes:

5. The preparation method according to claim 1, wherein the modifier is a composite rare earth aluminum alloy, aluminum titanium or a combination of aluminum titanium boron intermediate alloys, and the step S3 includes:

6. The method according to claim 5, wherein the preparing of the composite rare earth aluminum alloy includes:

step S311, providing the aluminum melt;

7. The method according to claim 6, wherein in step S313, the Al-Sr intermediate alloy is added in a spaced relation to the Al-Ti or Al-Ti-B intermediate alloy, and the rare earth aluminum alloy is added before the Al-Sr intermediate alloy and the Al-Ti or Al-Ti-B intermediate alloy, or together with the first-added one, or in a gap between the Al-Sr intermediate alloy and the Al-Ti or Al-Ti-B intermediate alloy.

8. The preparation method according to claim 7, wherein in step S313, the rare earth aluminum alloy, the aluminum-strontium intermediate alloy, the aluminum-titanium or the aluminum-titanium-boron intermediate alloy are sequentially added into the aluminum melt at intervals.

9. The production method according to claim 1, wherein the modifier accounts for 0.4 to 0.6 wt% of the total amount of the modified aluminum alloy, and the rare earth metal: strontium: the mass ratio of the total amount of titanium or titanium boron is 1 (0.1-1.2): (0.1-1.2).

10. The method of claim 1, wherein the modifier is refined prior to being added to the aluminum melt, the refining comprising:

11. The preparation method of the alloy material according to claim 10, wherein the addition amount of the refining agent accounts for 0.1-0.3% of the mass of the added melt, and the addition amount of the slag removing agent accounts for 0.1-0.3% of the mass of the added melt;

the refining agent comprises the following components in percentage by mass:

the slag remover comprises the following components in percentage by mass:

12. The method of claim 11, wherein the melt is tested for density before and during refining when the melt has a density of less than 2.65g/cm³If so, carrying out the refining treatment;

13. A modified aluminum alloy characterized by being produced by the production method according to any one of claims 1 to 12.