Preparation method of Al-Zr-B intermediate alloy, refiner and application of refiner

Abstract

The invention discloses a preparation method of an Al-Zr-B intermediate alloy, a refiner and application of the refiner. The method comprises the following steps: heating and melting a pure aluminum ingot to form molten aluminum; when the temperature of the molten aluminum rises to 750-900 DEG C, Al-B intermediate alloy is added, and molten metal is formed through stirring and melting; zrO2 is added into the molten metal, heat preservation is conducted for 30-120 min at the temperature of 750-900 DEG C, and alloy liquid is formed through stirring; and after the alloy liquid is subjected to degassing and slagging-off, the alloy liquid is solidified, and the Al-Zr-B intermediate alloy is obtained. According to the preparation method of the Al-Zr-B intermediate alloy, the refiner and the application of the Al-Zr-B intermediate alloy, the adding sequence of alloy elements is optimized, so that the agglomeration phenomenon of ZrB2 is avoided; alB2 and AlB12 are dissolved through an aluminothermic reduction reaction, and fine ZrB2 particles which are evenly distributed are generated.

Description

Technical Field

[0001] The invention belongs to the technical field of alloy materials, and in particular relates to a preparation method of an Al-Zr-B master alloy, a refiner and application thereof. Background Art

[0002] For aluminum alloys, grain refinement can improve the strength of the material without reducing its plasticity and toughness. Therefore, various methods are usually used to obtain aluminum alloy castings with fine grains when casting aluminum alloys. Among them, the method of adding grain refiners is simple, effective, and easy to operate. It is currently the most widely used in industrial production.

[0003] Al-Ti-B master alloy is a widely used aluminum alloy refiner. However, in 7 series aluminum alloys, the Ti in the refiner will react with Zr, Cr, V and other elements in the aluminum alloy, and its refinement effect will be weakened, which is the "poisoning effect". To solve this problem, Al-Zr-B master alloy came into being.

[0004] When Al-Zr-B master alloy is added to aluminum alloy melt as a refiner, the ZrB2 surface will first adsorb the ZrAl3 layer, and then ZrAl3 will play a heterogeneous nucleation role on α-Al. Therefore, the size and distribution of ZrB2 determine the grain refinement ability of Al-Zr-B master alloy. However, the Al-Zr-B master alloy prepared in the prior art has a poor refinement effect, which easily leads to the coarsening of the grain size of the ingot.

[0005] Therefore, it is necessary to provide a new solution to the above technical problems. Summary of the invention

[0006] The object of the present invention is to provide a preparation method of an Al-Zr-B master alloy, a refiner and application thereof, which can effectively prevent the agglomeration of ZrB2 and improve the grain refinement effect.

[0007] To achieve the above purpose, the technical solution provided by the present invention is as follows:

[0008] In a first aspect, the present invention provides a method for preparing an Al-Zr-B master alloy, comprising:

[0009] The pure aluminum ingot is heated and melted to form aluminum liquid; when the temperature of the aluminum liquid rises to 750-900° C., an Al-B intermediate alloy is added, and the mixture is stirred and melted to form a metal liquid; ZrO2 is added to the metal liquid, and the mixture is kept at 750-900° C. for 30-120 minutes, and stirred to form an alloy liquid; the alloy liquid is degassed and slag-stripped, and then the alloy liquid is solidified to obtain an Al-Zr-B intermediate alloy.

[0010] In one or more embodiments, the content of Zr in the Al-Zr-B master alloy is 1-12 wt.%.

[0011] In one or more embodiments, the content of B in the Al-Zr-B master alloy is 1 to 3 wt.%.

[0012] In one or more embodiments, the mass ratio of Zr to B in the Al-Zr-B master alloy is (1-12):1.

[0013] In one or more embodiments, the mass ratio of Zr to B in the Al-Zr-B master alloy is (5-10):1.

[0014] In one or more embodiments, the ZrO2 undergoes a thermite reaction in the molten metal.

[0015] In one or more embodiments, Zr and B in the Al-Zr-B master alloy form uniformly distributed ZrB2 grains.

[0016] In a second aspect, the present invention provides a refiner, comprising the Al-Zr-B master alloy prepared by the aforementioned method.

[0017] In a third aspect, the present invention provides a method for applying the aforementioned refiner, comprising:

[0018] Aluminum or aluminum alloy is heated and melted to form a melt; the refiner is added to the melt, stirred and melted to form a mixed melt, and cast to obtain an ingot.

[0019] In one or more embodiments, the amount of the refiner added is such that the mass of Zr accounts for 0.05-0.1% of the total mass of the mixed melt.

[0020] Compared with the prior art, the preparation method, refiner and application of the Al-Zr-B master alloy provided by the present invention optimize the addition sequence of alloy elements to avoid the agglomeration of ZrB2; the AlB2 and AlB 12 , generating small and evenly distributed ZrB2 particles. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the prior art descriptions are briefly introduced below. Obviously, the drawings described below are only some embodiments recorded in the present invention, and for ordinary technicians in this field, other drawings can be obtained based on these drawings without creative work.

[0022] Figure 1Flow chart of a method for preparing an Al-Zr-B master alloy according to an embodiment of the present invention;

[0023] Figure 2 This is a morphology diagram of ZrB2 in the Al-Zr-B master alloy prepared in Example 1 of the present invention;

[0024] Figure 3 This is a grain morphology diagram of the 1××× aluminum alloy anode coated in Example 1 of the present invention;

[0025] Figure 4 This is a grain morphology diagram of the 1××× aluminum alloy anode coated in Example 2 of the present invention;

[0026] Figure 5 This is a grain morphology diagram of the 1××× aluminum alloy anode coated in Example 3 of the present invention;

[0027] Figure 6 This is a morphology diagram of ZrB2 in the Al-Zr-B master alloy prepared in Comparative Example 1 of the present invention;

[0028] Figure 7 This is a grain morphology diagram of the 1××× aluminum alloy anode after coating in Comparative Example 1 of the present invention;

[0029] Figure 8 This is a grain morphology diagram of the 1××× aluminum alloy anode after coating in Comparative Example 2 of the present invention;

[0030] Fig. 9 This is a grain morphology diagram of the 1××× aluminum alloy anode after coating in Comparative Example 3 of the present invention. DETAILED DESCRIPTION

[0031] In order to enable those skilled in the art to better understand the technical solutions in the present invention, the technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work should fall within the scope of protection of the present invention.

[0032] It should be noted that in the following description, the "%" indicating the amount is a weight basis unless otherwise specified. Unless otherwise specified, all numbers used in this specification and claims to indicate characteristic dimensions, quantities and physical properties should be understood to be modified by the term "about" in all cases. Therefore, unless otherwise specified, the numerical parameters listed in the above specification and the attached claims are approximate values, and those skilled in the art can use the teachings disclosed herein to seek to obtain the desired properties and appropriately change these approximate values. The use of numerical ranges expressed as endpoints includes all numbers within the range and any range within the range, for example, 1 to 5 includes 1, 1.2, 1.4, 1.55, 2, 2.75, 3, 3.80, 4 and 5, etc.

[0033] The invention is proposed based on an in-depth analysis of existing aluminum alloy grain refinement technology. It is well known that grain refinement of aluminum alloys can significantly improve the mechanical properties of materials while maintaining their excellent plasticity and toughness. However, in actual production, the existing Al-Ti-B master alloy refiner has a reduced refinement effect in certain specific aluminum alloys (such as 7 series aluminum alloys) due to the "poisoning effect". To solve this problem, Al-Zr-B master alloy was developed as an alternative, but the existing preparation method still has the defects of ZrB2 agglomeration and uneven distribution, which directly leads to unsatisfactory grain refinement effect and limits the wide application of the refiner.

[0034] The inventors studied the formation mechanism and distribution law of ZrB2 particles in the prior art and found that the generation process and reaction conditions of ZrB2 directly determine the nucleation ability of the refiner. The existing preparation method is prone to agglomeration of ZrB2 particles due to improper reaction control, which in turn affects the refinement effect. In the prior art, when preparing Al-Zr-B master alloys, the B element is generally in the form of AlB2 and AlB 12 After adding Zr source, Zr will exist in AlB2 and AlB 12 A ZrB2 ring is formed around the particles, leading to aggregation.

[0035] In view of these problems, the present invention proposes a method for preparing an Al-Zr-B master alloy based on optimized reaction conditions and process steps. The method ensures that ZrB2 particles are small and evenly distributed when generated in aluminum liquid through reasonable raw material selection and process control, thereby improving the grain refining ability of the alloy.

[0036] The implementation ideas of the present invention mainly revolve around the following core points: first, the order of adding alloy elements is optimized to avoid the agglomeration of ZrB2; second, the aluminothermic reduction reaction is utilized to not only efficiently generate ZrB2 particles, but also the heat generated during the reaction process is utilized to improve the reaction efficiency and reduce energy consumption; finally, through appropriate temperature control and stirring means, the uniform distribution of ZrB2 particles is further ensured.

[0037] Please refer to Figure 1 FIG. 1 is a process flow chart of a method for preparing an Al-Zr-B master alloy in an embodiment of the present invention. The method for preparing an Al-Zr-B master alloy specifically comprises the following steps:

[0038] S101: heating and melting the pure aluminum ingot to form aluminum liquid.

[0039] It should be noted that the melting of aluminum ingots provides a liquid carrier for the subsequent addition of other alloying elements and chemical reactions. Specifically, the melting point of aluminum is about 660°C, but in order to ensure that the aluminum is completely melted and has good fluidity and reactivity, the temperature of the aluminum liquid is usually raised to between 750°C and 900°C, which can provide higher energy for subsequent reactions, thereby accelerating the dissolution and reaction of other substances. In actual operation, the melting of aluminum ingots can be carried out in an industrial melting furnace. Using an efficient electric furnace or induction furnace can accurately control the temperature and ensure the stability of the melting process.

[0040] The aluminum liquid provides a reaction carrier for the Al-B master alloy and ZrO2 added later. The use of pure aluminum ingots can ensure that the aluminum liquid has a high purity and avoid the interference of impurities in subsequent reactions. The formation of aluminum liquid is not only a change in physical state, but more importantly, it provides a suitable reaction medium for subsequent chemical reactions.

[0041] S102: When the temperature of the aluminum liquid rises to 750-900° C., add Al—B master alloy, stir and melt to form a molten metal.

[0042] In step S102, the B element is introduced into the melt by adding Al-B master alloy to form AlB2 or AlB 12 It exists in the form of ZrB2 particles, laying the foundation for the subsequent generation of ZrB2 particles. When the aluminum liquid is heated to 750-900℃, it has enough thermal energy to make the Al-B master alloy melt quickly and evenly disperse in the aluminum liquid.

[0043] Al-B master alloy is the main source of B element. Usually, in industrial production, Al-B master alloys with different B contents (such as 3% or 5% B-containing alloys) can be used to make the proportion according to the needs of the target alloy. At this time, the stirring operation can promote the Al-B master alloy to be fully mixed with the aluminum liquid, so that the B element is in the form of AlB2 or AlB12 The form of is evenly distributed in the aluminum liquid.

[0044] The specific implementation method of stirring can be determined according to the equipment and process requirements, and mechanical stirring or electromagnetic stirring can be used. Mechanical stirring can be performed by a stirring paddle with a high temperature resistant coating, and the stirring speed and time are adjusted according to parameters such as the temperature and viscosity of the melt to ensure the stirring effect. Electromagnetic stirring circulates the aluminum liquid through eddy currents generated by electromagnetic induction, without direct contact with the metal liquid, which can reduce oxidation and contamination of the metal.

[0045] S103: adding ZrO2 to the molten metal, keeping the temperature at 750-900°C for 30-120 minutes, and stirring to form an alloy liquid.

[0046] As the source of Zr, ZrO2 undergoes aluminothermic reduction reaction with aluminum in the melt in high-temperature molten metal, releasing a large amount of heat and raising the temperature of the melt. The aluminothermic reaction raises the melt temperature, thereby dissolving AlB2 and AlB 12 , forming a uniform Al-B metal solution. Through this process, Zr reacts with B to generate fine and evenly distributed ZrB2 particles, thereby increasing the number density of ZrB2 in the Al-Zr-B alloy. This reaction not only reduces Zr, but also generates fine and evenly distributed ZrB2 particles. These particles play a role in grain refinement in aluminum alloys through heterogeneous nucleation.

[0047] At high temperatures, the addition of ZrO2 is prone to local overheating or uneven distribution, so stirring can ensure that ZrO2 is evenly diffused throughout the molten metal, avoid particle aggregation, and promote the uniform generation of ZrB2 particles. The stirring method can be mechanical stirring or electromagnetic stirring, depending on the process equipment.

[0048] ZrO2 is usually added in powder form and gradually added to the molten metal through a conveying device to avoid drastic temperature changes or incomplete reaction caused by adding it all at once. For example, pre-dried ZrO2 powder can be slowly added to the melt through an aluminum pipe, while keeping the temperature of the molten metal within a suitable range and stirring to ensure the uniformity of the reaction.

[0049] S104: After degassing and slagging the alloy liquid, the alloy liquid is solidified to obtain an Al-Zr-B master alloy.

[0050] In aluminum alloy melt, gases (especially hydrogen) are easily dissolved, and these gases will form pores during the solidification process, affecting the density and mechanical properties of the alloy. Therefore, through degassing treatment, such as blowing argon or nitrogen into the melt, the bubbles will take away the dissolved gas during the rising process, which can effectively reduce the gas content in the alloy.

[0051] During the smelting process, oxides and other impurities are inevitably produced, which will form a slag layer on the surface of the melt. Through the slag removal operation, these impurities can be effectively removed to prevent them from mixing into the alloy during the solidification process and affecting the purity and quality of the alloy.

[0052] In an exemplary embodiment, the content of Zr in the Al-Zr-B master alloy is preferably 1-12 wt.%, the content of B is preferably 1-3 wt.%, and the mass ratio of Zr to B is preferably (1-12): 1. More preferably, the mass ratio of Zr to B in the Al-Zr-B master alloy is (5-10): 1.

[0053] The main function of Zr is to react with B to generate ZrB2 particles, which refine the grains in the aluminum alloy through heterogeneous nucleation. When the Zr content is too low, the number of ZrB2 particles generated is insufficient, and it is difficult to form enough nucleation points, resulting in poor grain refinement. When the Zr content is too high, the number density of ZrB2 particles is too large, and the particles may aggregate, which is not conducive to grain refinement and increases material costs. Therefore, controlling the Zr content between 1 and 12 wt.% can ensure sufficient refinement effect while avoiding ZrB2 particle aggregation.

[0054] Too low a B content will limit the reaction between Zr and B, resulting in insufficient ZrB2 particle formation; while too high a B content may result in AlB2 or AlB 12 Excessive generation of ZrB2 affects the overall performance of the alloy and the uniform distribution of ZrB2. Therefore, the content of B is preferably 1-3wt.%, which can ensure sufficient generation of ZrB2 and avoid the formation of unnecessary by-products.

[0055] The main purpose of designing the mass ratio of Zr to B is to ensure a reasonable reaction ratio between Zr and B, so as to generate an appropriate amount of uniformly distributed ZrB2 particles. A too low mass ratio (i.e., too little Zr relative to B) will result in insufficient ZrB2 generation and inability to fully refine the grains; while a too high mass ratio (i.e., too much Zr relative to B) may result in too many ZrB2 particles and agglomeration.

[0056] The present invention also provides a refiner, which comprises the Al-Zr-B master alloy prepared by the above method.

[0057] The present invention also provides an application method of the above-mentioned refiner, which specifically comprises: heating aluminum or aluminum alloy to melt to form a melt; adding the refiner to the melt, stirring and melting to form a mixed melt, and casting to obtain an ingot. The amount of the refiner added is such that the mass of Zr accounts for 0.05-0.1% of the total mass of the mixed melt.

[0058] The present invention will be further described below in conjunction with specific embodiments.

[0059] Example 1

[0060] Al-Zr-B master alloy composition: Zr 5%, B 1%, and the balance is Al.

[0061] Preparation process:

[0062] (1) Place pure aluminum ingots in a melting furnace and heat until completely melted;

[0063] (2) After the temperature rises to 750°C, add Al-B master alloy and stir the molten metal;

[0064] (3) Weighing ZrO2 powder according to the mass ratio of Al-Zr-B master alloy, heating and drying after ball milling to remove moisture, then adding the powder to the molten metal through the aluminum alloy tube at a uniform adding rate, stirring the molten metal at the same time, and keeping the temperature at 750°C for 120 minutes to make it undergo aluminothermic reduction reaction to form an alloy liquid;

[0065] (4) Degassing and slag removal are performed to solidify the molten alloy liquid, and then deformation is performed to form Al-Zr-B alloy wire.

[0066] After the Al-Zr-B master alloy is prepared, it is added to 1××× aluminum alloy as a refining agent to obtain 1××× aluminum alloy ingot, wherein the added amount of the Al-Zr-B master alloy is that the mass of Zr accounts for 0.06% of the total mass of the mixed melt.

[0067] Figure 2 This is the morphology of ZrB2 in the Al-Zr-B master alloy prepared in Example 1. It can be seen that ZrB2 has not agglomerated. Figure 3 This is the grain morphology of the 1××× aluminum alloy after anode coating in Example 1.

[0068] Example 2

[0069] Al-Zr-B master alloy composition: Zr 5%, B 1%, and the balance is Al.

[0070] Preparation process:

[0071] (1) Place pure aluminum ingots in a melting furnace and heat until completely melted;

[0072] (2) After the temperature rises to 750°C, add Al-B master alloy and stir the molten metal;

[0073] (3) Weighing ZrO2 powder according to the mass ratio of Al-Zr-B master alloy, heating and drying after ball milling to remove moisture, then adding the powder to the molten metal through the aluminum alloy tube at a uniform adding rate, stirring the molten metal at the same time, and keeping the temperature at 800°C for 120 minutes to make it undergo aluminothermic reduction reaction to form an alloy liquid;

[0074] (4) Degassing and slag removal are performed to solidify the molten alloy liquid, and then deformation is performed to form Al-Zr-B alloy wire.

[0075] After the Al-Zr-B master alloy is prepared, it is added to 1××× aluminum alloy as a refining agent to obtain 1××× aluminum alloy ingot, wherein the added amount of the Al-Zr-B master alloy is that the mass of Zr accounts for 0.06% of the total mass of the mixed melt.

[0076] Figure 4 This is the grain morphology of the 1××× aluminum alloy after anode coating in Example 2.

[0077] Example 3

[0078] Al-Zr-B master alloy composition: Zr 9.5%, B 1%, and the balance is Al.

[0079] Preparation process:

[0080] (1) Place pure aluminum ingots in a melting furnace and heat until completely melted;

[0081] (2) After the temperature rises to 750°C, add Al-B master alloy and stir the molten metal;

[0082] (3) Weighing ZrO2 powder according to the mass ratio of Al-Zr-B master alloy, heating and drying after ball milling to remove moisture, then adding the powder to the molten metal through the aluminum alloy tube at a uniform adding rate, stirring the molten metal at the same time, and keeping the temperature at 800°C for 120 minutes to make it undergo aluminothermic reduction reaction to form an alloy liquid;

[0083] (4) Degassing and slag removal are performed to solidify the molten alloy liquid, and then deformation is performed to form Al-Zr-B alloy wire.

[0084] After the Al-Zr-B master alloy is prepared, it is added to 1××× aluminum alloy as a refining agent to obtain 1××× aluminum alloy ingot, wherein the added amount of the Al-Zr-B master alloy is that the mass of Zr accounts for 0.06% of the total mass of the mixed melt.

[0085] Figure 5 This is the grain morphology of the 1××× aluminum alloy after anode coating in Example 2.

[0086] Comparative Example 1

[0087] Compared with Example 1, the ZrO2 powder is replaced by Al-Zr intermediate alloy, and the other conditions are the same as those of Example 1.

[0088] Figure 6 This is the morphology of ZrB2 in the Al-Zr-B master alloy prepared in Comparative Example 1. It can be seen that a ZrB2 ring is formed and the agglomeration phenomenon is serious. Figure 7 This is the grain morphology of the 1××× aluminum alloy anode after coating in Comparative Example 1.

[0089] Comparative Example 2

[0090] Compared with Example 1, when preparing the Al-Zr-B master alloy, the Al-B master alloy and the ZrO2 powder are added simultaneously, and the other conditions are the same as those in Example 1.

[0091] Figure 8 This is the grain morphology of the 1××× aluminum alloy anode after coating in Comparative Example 2.

[0092] Comparative Example 3

[0093] Compared with Example 1, when preparing the Al-Zr-B master alloy, ZrO2 powder is added first, and then the Al-B master alloy is added after stirring. Other conditions are the same as those in Example 1.

[0094] Fig. 9 This is the grain morphology of the 1××× aluminum alloy anode after coating in Comparative Example 3.

[0095] Table 1 Comparison of grain refining ability of Al-Zr-B master alloy on 1××× aluminum alloy

[0096] Average grain size of 1××× alloy Example 1 110um Example 2 96um Example 3 85um Comparative Example 1 280um Comparative Example 2 198um Comparative Example 3 220um

[0097] Table 1 is a comparison table of the grain refining ability of the Al-Zr-B master alloys prepared in the examples and comparative examples to the 1××× alloy. It can be seen from Table 1 that the grain refining ability of the Al-Zr-B master alloy prepared by the method of the present invention is enhanced.

[0098] It will be apparent to those skilled in the art that the invention is not limited to the details of the exemplary embodiments described above and that the invention can be implemented in other specific forms without departing from the spirit or essential features of the invention. Therefore, the embodiments should be considered exemplary and non-limiting in all respects, and the scope of the invention is defined by the appended claims rather than the foregoing description, and it is intended that all variations falling within the meaning and scope of the equivalent elements of the claims be included in the invention. Any reference numeral in a claim should not be considered as limiting the claim to which it relates.

[0099] In addition, it should be understood that although the present specification is described according to implementation modes, not every implementation mode contains only one independent technical solution. This description of the specification is only for the sake of clarity. Those skilled in the art should regard the specification as a whole. The technical solutions in each embodiment may also be appropriately combined to form other implementation modes that can be understood by those skilled in the art.

Claims

1. A method for preparing an Al-Zr-B master alloy, characterized in that: include: The pure aluminum ingot is heated and melted to form aluminum liquid; When the temperature of the aluminum liquid rises to 750-900° C., adding Al-B master alloy, stirring and melting to form a metal liquid; Adding ZrO2 to the molten metal, keeping the temperature at 750-900°C for 30-120 minutes, and stirring to form an alloy liquid; After degassing and slagging the alloy liquid, the alloy liquid is solidified to obtain an Al-Zr-B intermediate alloy.

2. The method for preparing the Al-Zr-B master alloy according to claim 1, characterized in that: The content of Zr in the Al-Zr-B master alloy is 1-12 wt.%.

3. The method for preparing the Al-Zr-B master alloy according to claim 1, characterized in that: The content of B in the Al-Zr-B master alloy is 1-3 wt.%.

4. The method for preparing the Al-Zr-B master alloy according to claim 1, characterized in that: The mass ratio of Zr to B in the Al-Zr-B master alloy is (1-12):

1.

5. The method for preparing the Al-Zr-B master alloy according to claim 4, characterized in that: The mass ratio of Zr to B in the Al-Zr-B master alloy is (5-10):

1.

6. The method for preparing the Al-Zr-B master alloy according to claim 1, characterized in that: The ZrO2 undergoes a thermite reaction in the molten metal.

7. The method for preparing the Al-Zr-B master alloy according to claim 1, characterized in that: Zr and B in the Al-Zr-B master alloy form uniformly distributed ZrB2 grains.

8. A refiner comprising the Al-Zr-B master alloy prepared by the method according to any one of claims 1 to 7.

9. A method for applying the refiner according to claim 8, characterized in that: include: heating and melting aluminum or aluminum alloy to form a melt; The refiner is added into the melt, stirred and melted to form a mixed melt, and then cast to obtain an ingot.

10. The method for applying a refiner according to claim 9, characterized in that: The amount of the refiner added is such that the mass of Zr accounts for 0.05-0.1% of the total mass of the mixed melt.

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