A method for improving the divorced eutectic in SuperDyma alloys

Abstract

This invention discloses a method for improving the dimorphic eutectic in SuperDyma alloys. The mass percentages of the components in the alloy are: Al: 11%, Mg: 3%, Si: 0.2%, B: 0.06-0.09%, with the remainder being Zn. First, SuperDyma alloys are obtained by casting using different cooling methods. The alloy liquid cooled using a copper mold exhibits the most uniform solidification structure, with a significant improvement in dimorphic eutectic. By adding B element to the SuperDyma alloy through alloying, the solidification structure is refined, further improving the dimorphic eutectic phenomenon and consequently enhancing the alloy's corrosion resistance.

Description

Technical Field

[0001] This invention belongs to the field of hot-dip galvanized aluminum-magnesium alloys, and specifically relates to a method for improving the segregated eutectic in SuperDyma alloys. Background Technology

[0002] SuperDyma alloy is a highly regarded high-performance alloy whose unique properties make it widely used in various industrial fields. The main components of this alloy include Zn, Al, Mg and Si, and the precise combination of these elements gives SuperDyma its outstanding properties.

[0003] First, SuperDyma alloys are renowned for their exceptional corrosion resistance, a characteristic primarily resulting from the combined protective properties of zinc and the corrosion resistance of aluminum. Therefore, SuperDyma alloys are widely used in applications requiring long-term exposure to harsh corrosive environments, such as marine engineering, chemical equipment, and building structures. Second, SuperDyma alloys possess high strength, making them ideal for manufacturing lightweight products. High strength helps reduce product weight while maintaining structural stability, which is of great significance in fields such as automotive manufacturing, aerospace, and civil engineering.

[0004] However, an important aspect that cannot be ignored when discussing SuperDyma alloys is the divorced eutectic phenomenon in their microstructure. This phenomenon stems from the influence of alloy composition and solidification process. Compositional differences in SuperDyma alloys, as well as variations in temperature gradients and cooling rates during solidification, lead to the formation of crystals of different compositions in different regions. Therefore, the presence of different crystal structures and compositional distributions within the alloy can potentially affect its properties and corrosion resistance.

[0005] The formation of dioecious eutectic is usually caused by the non-uniform distribution of alloy composition and temperature changes during solidification. Therefore, these factors need to be carefully considered and controlled when preparing and applying SuperDyma alloys to meet the needs of different industrial sectors. Summary of the Invention

[0006] The purpose of this section is to outline some aspects of embodiments of the present invention and to briefly describe some preferred embodiments. Simplifications or omissions may be made in this section, as well as in the abstract and title of this application, to avoid obscuring the purpose of these documents; however, such simplifications or omissions should not be construed as limiting the scope of the invention.

[0007] In view of the problems existing in the above and / or prior art, the present invention is proposed.

[0008] Therefore, the purpose of this invention is to overcome the shortcomings of the prior art and provide a method for improving the divorced eutectic in SuperDyma alloys.

[0009] To solve the above-mentioned technical problems, the present invention provides the following technical solution: a method for improving the divorced eutectic in SuperDyma alloys, comprising,

[0010] Weigh out the SuperDyma alloy, Al-B master alloy, Zn ingot, and Mg ingot;

[0011] Place the SuperDyma alloy, Zn ingot, and Mg ingot into a crucible and set the temperature to 700-720℃. After the alloy in the crucible melts, clamp the Al-B and send it into the molten pool. Stir continuously until it melts completely, and then hold it at the temperature for 20-30 minutes.

[0012] Sprinkle a covering agent evenly on the surface of the alloy liquid, reduce the furnace temperature to 500-510℃, and then hold for 10-15 minutes.

[0013] After the heat preservation is completed, the alloy liquid is poured into a copper mold at room temperature to obtain a SuperDyma alloy containing B.

[0014] As a preferred embodiment of the method described in this invention, the B-containing SuperDyma alloy has the following mass percentages: Al: 11%, Mg: 3%, Si: 0.2%, B: 0.03-0.15%, with the remainder being Zn.

[0015] As a preferred embodiment of the method described in this invention, the mass percentage of each component in the B-containing SuperDyma alloy is: Al: 11%, Mg: 3%, Si: 0.2%, B: 0.6-0.09%, with the remainder being Zn.

[0016] As a preferred embodiment of the method described in this invention, the mass percentage of each component in the B-containing SuperDyma alloy is Al: 11%, Mg: 3%, Si: 0.2%, B: 0.09%, and the remainder is Zn.

[0017] As a preferred embodiment of the method described in this invention, the covering agent is a uniformly mixed solid powder containing 35-45% CaCl2, 25-35% KCl and 20-30% NaCl by mass after dehydration treatment.

[0018] In a preferred embodiment of the method described in this invention, the covering agent is composed of 40% CaCl2, 30% KCl and 30% NaCl.

[0019] Beneficial effects of this invention:

[0020] The SuperDyma alloy ingot prepared by the method of the present invention has virtually no heterogeneous divorced eutectic in its solidification structure, and at the same time, the Al / MgZn2 binary eutectic in the alloy becomes finer and more uniform. Tests have shown that the corrosion resistance of the SuperDyma alloy ingot prepared by the present invention is also improved. Attached Figure Description

[0021] To more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings used in the description of the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort. Wherein:

[0022] Figure 1 This is a microstructure diagram of the alloy prepared in Comparative Example 1 of the present invention;

[0023] Figure 2 This is a microstructure diagram of the alloy obtained in Example 1 of the present invention;

[0024] Figure 3 This is a microstructure diagram of the alloy obtained in Example 2 of the present invention;

[0025] Figure 4 This is a microstructure diagram of the alloy obtained in Example 3 of the present invention;

[0026] Figure 5 This is a microstructure diagram of the alloy obtained in Example 4 of the present invention;

[0027] Figure 6 This is a microstructure diagram of the alloy obtained in Example 5 of the present invention;

[0028] Figure 7 This is a microstructure diagram of the alloy obtained in Example 6 of the present invention;

[0029] Figure 8 This is a microstructure diagram of the alloy obtained in Example 7 of the present invention. Detailed Implementation

[0030] To make the above-mentioned objects, features and advantages of the present invention more apparent and understandable, the specific embodiments of the present invention will be described in detail below with reference to the examples in the specification.

[0031] Many specific details are set forth in the following description in order to provide a full understanding of the invention. However, the invention may also be practiced in other ways different from those described herein, and those skilled in the art can make similar extensions without departing from the spirit of the invention. Therefore, the invention is not limited to the specific embodiments disclosed below.

[0032] Secondly, the term "one embodiment" or "embodiment" as used herein refers to a specific feature, structure, or characteristic that may be included in at least one implementation of the present invention. The phrase "in one embodiment" appearing in different places in this specification does not necessarily refer to the same embodiment, nor is it a single or selective embodiment that is mutually exclusive with other embodiments.

[0033] Example 1

[0034] (1) Weigh the SuperDyma alloy: 11% Al, 3% Mg, 0.2% Si, and the remainder is Zn;

[0035] (2) Place the SuperDyma alloy into a crucible and set the temperature to 510°C. Sprinkle a covering agent evenly on the surface of the alloy liquid inside the crucible (the covering agent is a uniformly mixed solid powder with a mass percentage of 40% CaCl2, 30% KCl and 30% NaCl after dehydration treatment), set the temperature to 510°C, and then keep it at that temperature for 15 minutes.

[0036] (3) After the heat preservation is completed, the alloy liquid is poured into a room temperature steel mold, and then the steel mold is immediately placed in water to finally obtain a Zn-11%Al-3%Mg-0.2%Si alloy with a diameter of 10mm.

[0037] The solidification structure of the alloy obtained through the above steps, after being cooled in water from a room temperature steel mold, is as follows: Figure 2 As shown, it can be seen that, with Figure 1 Compared to the solidified structure of the alloy cooled to room temperature in a steel mold, the η-Zn phase still exists and grows around the α-Al dendrites, which is consistent with... Figure 1 In contrast, the bulky η-Zn phase becomes smaller, the diameter of α-Al is reduced, and the dendrites become more compact. The Al / MgZn2 binary eutectic structure is uniform, but some divorced eutectic still exists.

[0038] Example 2

[0039] (1) Weigh the SuperDyma alloy: 11% Al, 3% Mg, 0.2% Si, and the remainder is Zn;

[0040] (2) Place the SuperDyma alloy into a crucible and set the temperature to 510°C. Sprinkle a covering agent evenly on the surface of the alloy liquid inside the crucible (the covering agent is a uniformly mixed solid powder with a mass percentage of 40% CaCl2, 30% KCl and 30% NaCl after dehydration treatment), set the temperature to 510°C, and then keep it at that temperature for 15 minutes.

[0041] (3) After the heat preservation is completed, the alloy liquid is poured into a copper mold at room temperature to obtain a Zn-11%Al-3%Mg-0.2%Si alloy with a diameter of 10mm.

[0042] The solidification structure of the alloy obtained through the above steps and cooled in a copper mold at room temperature is as follows: Figure 3 As shown, it can be seen that, with Figure 1 and Figure 2 Compared to the solidification structure of the alloy shown, the overall structure of each phase is more refined and more uniformly distributed. No η-Zn phase is observed between α-Al dendrites. The ternary eutectic structure of Zn / Al / MgZn2 is refined, the size of the binary eutectic of Al / MgZn2 is reduced, and the separation eutectic structure is improved.

[0043] Example 3

[0044] (1) Weigh the SuperDyma alloy, Al-B alloy, Zn ingot, and Mg ingot according to the mass percentage of each element: 11% Al, 3% Mg, 0.2% Si, 0.03% B, and the remainder is Zn (SuperDyma alloy: 1000g, Zn ingot: 82.8396g, Mg ingot: 3.191424g, Al-3B: 10.96708g);

[0045] (2) Place the SuperDyma alloy, Zn ingot, and Mg ingot into a crucible and set the temperature to 720℃. After the alloy in the crucible melts, clamp Al-B and send it into the molten pool. Stir continuously until it melts completely, and then keep it at the temperature for 30 minutes.

[0046] (3) Sprinkle a covering agent evenly on the surface of the alloy liquid (the covering agent is a solid powder with a mass percentage of 40% CaCl2, 30% KCl and 30% NaCl after dehydration treatment), lower the furnace temperature to 510℃, and then keep it at that temperature for 15 minutes.

[0047] (4) After the heat preservation is completed, the alloy liquid is poured into a copper mold at room temperature to obtain a Zn-11%Al-3%Mg-0.2%Si-0.03%B alloy with a diameter of 10mm.

[0048] The solidification structure of the Zn-11%Al-3%Mg-0.2%Si-0.03%B alloy obtained by the above steps and cooled in a copper mold at room temperature is as follows: Figure 4 As shown, it can be seen that the α-Al dendrites and the Zn / Al / MgZn2 ternary eutectic structures are relatively small, while the Al / MgZn2 binary eutectic is larger and exhibits obvious separation eutectic.

[0049] Example 4

[0050] (1) Weigh the SuperDyma alloy, Al-B alloy, Zn ingot, and Mg ingot according to the mass percentage of each element: 11% Al, 3% Mg, 0.2% Si, 0.06% B, and the remainder is Zn (SuperDyma: 1000g, Zn ingot: 183.4216g, Mg ingot: 7.066224g, Al-3B: 24.28256g);

[0051] (2) Place the SuperDyma alloy, Zn ingot, and Mg ingot into a crucible, set the temperature to 720℃, and after the alloy in the crucible melts, clamp the Al-B alloy and transfer it into the molten pool. Stir continuously until completely melted, and then hold at that temperature for 30 minutes.

[0052] (3) Sprinkle a covering agent evenly on the surface of the alloy liquid (the covering agent is a solid powder with a mass percentage of 40% CaCl2, 30% KCl and 30% NaCl after dehydration treatment), lower the furnace temperature to 510℃, and then keep it at that temperature for 15 minutes.

[0053] (4) After the heat preservation is completed, the alloy liquid is poured into a copper mold at room temperature to obtain a Zn-11%Al-3%Mg-0.2%Si-0.06%B alloy with a diameter of 10mm.

[0054] The solidification structure of the Zn-11%Al-3%Mg-0.2%Si-0.06%B alloy obtained by the above steps and cooled in a copper mold at room temperature is as follows: Figure 5 As shown, it can be seen that there is no obvious divorced eutectic, the α-Al dendrites are relatively long and unevenly distributed, the Zn / Al / MgZn2 ternary eutectic structure is unevenly distributed, and the Al / MgZn2 binary eutectic is relatively large in size and loosely distributed inside the eutectic structure.

[0055] Example 5

[0056] (1) Weigh the SuperDyma alloy, Al-B alloy, Zn ingot, and Mg ingot according to the mass percentage of each element: 11% Al, 3% Mg, 0.2% Si, 0.09% B, and the remainder is Zn (SuperDyma alloy: 1000g, Zn ingot: 308.12112g, Mg ingot: 11.8702g, Al-3B: 40.7911g);

[0057] (2) Place the SuperDyma alloy, Zn ingot, and Mg ingot into a crucible and set the temperature to 720℃. After the alloy in the crucible melts, clamp Al-B and send it into the molten pool. Stir continuously until it melts completely, and then keep it at the temperature for 30 minutes.

[0058] (3) Sprinkle a covering agent evenly on the surface of the alloy liquid (the covering agent is a solid powder with a mass percentage of 40% CaCl2, 30% KCl and 30% NaCl after dehydration treatment), lower the furnace temperature to 510℃, and then keep it at that temperature for 15 minutes.

[0059] (4) After the heat preservation is completed, the alloy liquid is poured into a copper mold at room temperature to obtain a Zn-11%Al-3%Mg-0.2%Si-0.09%B alloy with a diameter of 10mm.

[0060] The solidification structure of the Zn-11%Al-3%Mg-0.2%Si-0.09%B alloy obtained by the above steps and cooled in a copper mold at room temperature is as follows: Figure 6 As shown, with Figure 5 Compared to the solidification structures of the alloys shown, it can be seen that the Zn / Al / MgZn2 ternary eutectic structure is significantly more uniformly distributed, and the Al / MgZn2 binary eutectic structure is more compact with no divergent eutectic phenomena observed. The α-Al dendrites are also shorter and finer.

[0061] Example 6

[0062] (1) Weigh the SuperDyma alloy, Al-B alloy, Zn ingot, and Mg ingot according to the mass percentage of each element: 11% Al, 3% Mg, 0.2% Si, 0.12% B, and the remainder is Zn (SuperDyma: 1000g, Zn ingot: 466.798g, Mg ingot: 17.9828g, Al-3B: 61.796g);

[0063] (2) Place the SuperDyma alloy, Zn ingot, and Mg ingot into a crucible and set the temperature to 720℃. After the alloy in the crucible melts, clamp Al-B and send it into the molten pool. Stir continuously until it melts completely, and then keep it at the temperature for 30 minutes.

[0064] (3) Sprinkle a covering agent evenly on the surface of the alloy liquid (the covering agent is a solid powder with a mass percentage of 40% CaCl2, 30% KCl and 30% NaCl after dehydration treatment), lower the furnace temperature to 510℃, and then keep it at that temperature for 15 minutes.

[0065] (4) After the heat preservation is completed, the alloy liquid is poured into a copper mold at room temperature. After the heat preservation is completed, the alloy liquid is poured into a copper mold at room temperature to obtain a Zn-11%Al-3%Mg-0.2%Si-0.12%B alloy with a diameter of 10mm.

[0066] The solidification structure of the Zn-11%Al-3%Mg-0.2%Si-0.09%B alloy obtained by the above steps and cooled in a copper mold at room temperature is as follows: Figure 7 As shown, with Figure 6 Compared to the solidification structure of the alloy shown, it can be seen that more divorced eutectic structures have appeared, which is consistent with... Figure 4 Compared to the solidification structure of the alloy shown, the divorced eutectic size is smaller.

[0067] Example 7

[0068] (1) Weigh the SuperDyma alloy, Al-B alloy, Zn ingot, and Mg ingot according to the mass percentage of each element: 11% Al, 3% Mg, 0.2% Si, 0.15% B, and the remainder is Zn (SuperDyma alloy: 1000g, Zn ingot: 675.528g, Mg ingot: 26.0244g, Al-3B: 89.4308g);

[0069] (2) Place the SuperDyma alloy, Zn ingot, and Mg ingot into a crucible and set the temperature to 720℃. After the alloy in the crucible melts, clamp Al-B and send it into the molten pool. Stir continuously until it melts completely, and then keep it at the temperature for 30 minutes.

[0070] (3) Sprinkle a covering agent evenly on the surface of the alloy liquid (the covering agent is a solid powder with a mass percentage of 40% CaCl2, 30% KCl and 30% NaCl after dehydration treatment), lower the furnace temperature to 510℃, and then keep it at that temperature for 15 minutes.

[0071] (4) After the heat preservation is completed, the alloy liquid is poured into a copper mold at room temperature. After the heat preservation is completed, the alloy liquid is poured into a copper mold at room temperature to obtain a Zn-11%Al-3%Mg-0.2%Si-0.15%B alloy with a diameter of 10mm.

[0072] The solidification structure of the Zn-11%Al-3%Mg-0.2%Si-0.09%B alloy obtained by the above steps and cooled in a copper mold at room temperature is as follows: Figure 8 As shown, with Figure 6 Compared to the solidification structure of the alloy shown, it can be seen that divorced eutectic still exists, the size of the Al / MgZn2 binary eutectic is reduced, the α-Al dendrites are coarser, and the Zn / Al / MgZn2 ternary eutectic structure is distributed between the α-Al dendrites. Figure 6 The ternary eutectic structure becomes loose.

[0073] Comparative Example 1

[0074] (1) Weigh the SuperDyma alloy: 11% Al, 3% Mg, 0.2% Si, and the remainder is Zn;

[0075] (2) Place the SuperDyma alloy into a crucible, set the temperature to 510℃, and then hold it for 15 minutes;

[0076] (3) After the heat preservation is completed, the alloy liquid is poured into a steel mold at room temperature to obtain a Zn-11%Al-3%Mg-0.2%Si alloy with a diameter of 10mm.

[0077] Figure 1 The microstructure of the alloy prepared in Comparative Example 1 is shown. It was found that in the solidification structure of the alloy cooled at room temperature using a steel mold, the α-Al phase was relatively coarse, and there were blocky or lamellar η-Zn phases between the α-Al dendrites, which grew around the α-Al phase. There were large Al / MgZn2 binary eutectic structures, and some Al / MgZn2 binary eutectic structures were not uniform.

[0078] Comparing alloys cast using different cooling methods revealed that the alloy cast using the fastest cooling copper mold had the finest solidification structure and improved the phenomenon of divorced eutectic. Secondly, by adding boron (B) to the SuperDyma alloy, the divorced eutectic in the solidification structure gradually disappeared with the addition of B, and the binary eutectic structure became more compact, while the ternary eutectic distribution became more uniform. When the B content exceeded 0.09%, divorced eutectic reappeared in the solidification structure of the alloy, and the α-Al dendrites became coarser, while the Zn / Al / MgZn2 ternary eutectic structure became looser.

[0079] It should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and are not intended to limit it. Although the present invention has been described in detail with reference to preferred embodiments, those skilled in the art should understand that modifications or equivalent substitutions can be made to the technical solutions of the present invention without departing from the spirit and scope of the technical solutions of the present invention, and all such modifications or substitutions should be covered within the scope of the present invention.

Claims

1. A method for improving the divorced eutectic in SuperDyma alloys, characterized in that: include, Weigh out the SuperDyma alloy, Al-B master alloy, Zn ingot, and Mg ingot; Place the SuperDyma alloy, Zn ingot, and Mg ingot into a crucible and set the temperature to 700~720℃. After the alloy in the crucible melts, clamp the Al-B and send it into the molten pool. Stir continuously until it melts completely, and then hold it at the temperature for 20~30 minutes. Sprinkle a covering agent evenly on the surface of the alloy liquid, reduce the furnace temperature to 500~510℃, and then hold for 10~15 minutes; After the heat preservation is completed, the alloy liquid is poured into a copper mold at room temperature to obtain a SuperDyma alloy containing B. The B-containing SuperDyma alloy has the following mass percentages: Al: 11%, Mg: 3%, Si: 0.2%, B: 0.03~0.15%, and the remainder is Zn.

2. The method as described in claim 1, characterized in that: The mass percentages of each component in the B-containing SuperDyma alloy are: Al: 11%, Mg: 3%, Si: 0.2%, B: 0.06~0.09%, with the remainder being Zn.

3. The method as described in claim 2, characterized in that: The mass percentages of each component in the B-containing SuperDyma alloy are Al: 11%, Mg: 3%, Si: 0.2%, B: 0.09%, and the remainder is Zn.

4. The method as described in claim 1, characterized in that: The covering agent is a uniformly mixed solid powder containing 35-45% CaCl2, 25-35% KCl and 20-30% NaCl by mass after dehydration treatment.

5. The method as described in claim 4, characterized in that: The covering agent consists of 40% CaCl2, 30% KCl and 30% NaCl.

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