Method for rapidly improving local toughness of amorphous alloy die-cast product

Abstract

The application provides a method for rapidly improving local toughness of an amorphous alloy die-casting product, comprising the following steps: selecting a position to be toughened on the amorphous alloy die-casting product which needs to be improved; performing transient heating by electrifying the position to be toughened; and spraying dry ice on the electrified heating position to rapidly reduce the electrified heating position to below room temperature. The technical method in the application is used for toughening the weak part of a structure product with a large length-width ratio, and further, once there is a more serious defect after the toughening treatment, the defect can be found in time, so that the defective product can be picked out.

Description

Technical Field

[0001] This invention belongs to the field of metal processing technology, and specifically relates to a method for rapidly improving the local toughness of amorphous alloy die-cast products. Background Technology

[0002] Bulk amorphous alloys possess a microstructure characterized by short-range order and long-range disorder, thus exhibiting macroscopic properties distinct from traditional crystalline alloys, such as excellent formability, high hardness, and high strength. Bulk amorphous alloys are currently in mass production applications in smartphones, laptops, sporting goods, medical devices, and automobiles, primarily used to fabricate complex structural components with high-precision dimensional requirements. The mainstream forming process for bulk amorphous alloys is die casting. Die casting produces amorphous parts with near-net-shape characteristics, offering unparalleled advantages in fabricating structural components with multiple high-precision requirements.

[0003] Bulk amorphous alloys are particularly advantageous in the fabrication of long, strip-shaped structural components. For example, the long, strip-shaped hinge structures used in smartphones and laptops are made from bulk amorphous alloys. These components are not only dimensionally stable, deformation-free, and high-strength, but also meet the assembly requirements of dozens of precise dimensions on a single structural component. The biggest defects in the actual manufacturing process of long, strip-shaped amorphous structural components come from porosity and impurities generated during die casting. This is because if the product size is too large, it will cause slight differences in the cooling rate of the amorphous alloy in different locations within the mold cavity, resulting in slight variations in the properties of the amorphous alloy in each part. If defects in amorphous alloy structural components occur in critical locations, such as areas with assembly holes or assembly pillars, it can lead to the overall failure of the product.

[0004] In the prior art, X-ray machines are often used to detect defects such as pores and impurities. However, the detection test can only help determine whether the defect exists. It does not help with how to improve the defect. Moreover, if the resolution of the defect is lower than the resolution of the detection equipment, the defect cannot be detected at all. Summary of the Invention

[0005] The purpose of this invention is to provide a method for rapidly improving the local toughness of amorphous alloy die-cast products, aiming to solve the technical problem of critical location failure caused by defects such as porosity and impurities in existing amorphous alloy structural parts. On the one hand, the technical method of this invention targets the weaker parts of structural parts with a large aspect ratio for toughening treatment. On the other hand, after toughening treatment, any serious defects can be detected in time, allowing defective products to be rejected.

[0006] To achieve the above-mentioned objectives, the technical solution adopted by this invention is as follows: The present invention provides a method for rapidly improving the local toughness of amorphous alloy die-cast products, applicable to elongated amorphous alloy die-cast products with an aspect ratio in the range of 2.5:1 to 15:1.

[0007] The specific method includes the following steps: S01, Select the toughening location on the amorphous alloy die-cast product that needs improvement; S02, an electrode is clamped at each end of the position to be toughened, and the distance between the two electrodes is in the range of 5mm to 15mm; S03, a high-voltage direct current is applied between the two electrodes to raise the temperature of the area to be toughened from room temperature to 0.92T within 8-500 milliseconds. g ~0.95T g Within the range, the T g The temperature is the glass transition temperature of the amorphous alloy. After heating to the set temperature, the power is immediately cut off. S04, dry ice is sprayed onto the electrically heated position, causing the electrically heated position to rapidly drop below room temperature.

[0008] In the method for rapidly improving the local toughness of amorphous alloy die-cast products provided by this invention, a motor is clamped at each end of the area to be toughened. Then, a high-voltage current is used for instantaneous heating, followed by instantaneous cooling upon power cut-off. Through this rapid heating and cooling process, the free volume of the amorphous material at the local location of the product increases, thereby improving the local toughness of the product. The 0.92T mentioned in the technical solution of this invention... g ~0.95T g The temperature range refers to the temperature within 92% to 95% of the glass transition temperature of the amorphous alloy material, not exceeding T. g This is to avoid generating excessively high temperatures, which could cause the material to soften and deform the product.

[0009] Preferably, the amorphous alloy is a zirconium-based amorphous alloy, and the atomic percentage of zirconium in the alloy is greater than or equal to 55%. The method in this invention is suitable for zirconium-based amorphous materials, which have good formability and can produce products with unidirectionally large dimensions.

[0010] Preferably, in step S02, the difference between the maximum and minimum cross-sectional areas of the die-cast product between the two clamped electrodes does not exceed 30%. The area between the two clamped electrodes is the location to be toughened. To ensure uniform heating of this area, the cross-sectional or longitudinal section of the product at this location should not have significant differences, guaranteeing uniform heating when current flows. If the difference between the maximum and minimum cross-sections exceeds 30%, it will lead to uneven heating in the toughening area, failing to achieve the toughening effect and potentially causing burn-out of that section of the product.

[0011] Preferably, in step S02, the clamped electrode is a copper electrode, and its shape is adapted to the surface of the clamped amorphous alloy die-cast product, so that the copper electrode fits snugly against the surface of the clamped product. The electrode material is copper, and its shape allows for close contact with the product surface, which reduces the adverse effects of electrode resistance and contact resistance.

[0012] Preferably, in S03, the voltage of the high-voltage direct current is 180V~400V, and more preferably 240V~380V.

[0013] Preferably, in S03, a high-voltage DC power supply is used to provide high-voltage DC power, and the time accuracy of the high-voltage DC power supply is controlled to be ±0.1 milliseconds, and the processing time is further preferably 120~220 milliseconds.

[0014] Preferably, in step S04, dry ice is sprayed on both sides of the electrically heated position, thereby rapidly cooling the heated position to below room temperature through double-sided cooling. Compared to traditional high-pressure gas cooling, the use of bidirectional dry ice spraying allows for faster cooling of amorphous products.

[0015] Preferably, the amorphous alloy die-cast product is degreased and ultrasonically cleaned before improvement.

[0016] Preferably, the toughness of the improved toughening location is increased by 10% to 40%.

[0017] Preferably, the method is also used to determine whether the amorphous alloy die-cast product has defects. The determination method is as follows: if the toughened area after improvement is black or dark brown, it is determined to be defective. For products with defects such as pores or impurities in the heating area, the resistance at that location is significantly increased due to the presence of defects. During heating, the product will change color due to high-temperature oxidation at that location, and products with defects in that location can be visually selected.

[0018] The present invention provides a method for rapidly improving the local toughness of amorphous alloy die-cast products. This method can not only toughen the weaker parts of structural parts with a large aspect ratio, but also promptly detect serious defects after toughening treatment, allowing defective products to be rejected. Attached Figure Description

[0019] Figure 1 Metallographic test image (50x magnification) of the location where no change was observed after improvement in Example 1. Figure 2 The image shows a metallographic test pattern (50x magnification) of the blackened area after improvement in Example 1. Detailed Implementation

[0020] To make the objectives, technical solutions, and technical effects of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention are described clearly and completely. The embodiments described below are some embodiments of the present invention, but not all embodiments. All other embodiments obtained by those skilled in the art in conjunction with the embodiments of the present invention without creative effort are within the scope of protection of the present invention. Where specific conditions are not specified in the embodiments, conventional conditions or conditions recommended by the manufacturer shall be followed; where the manufacturers of reagents or instruments are not specified, they are all conventional products that can be purchased commercially.

[0021] Unless the context explicitly uses it otherwise, the singular form of a word should be understood as including the plural form of the word. The terms “comprising” or “having” are intended to specify the presence of a feature, quantity, step, operation, element, part, or combination thereof, but are not intended to exclude the presence or possible addition of one or more other features, quantities, steps, operations, elements, parts, or combinations thereof.

[0022] Example 1 The amorphous alloy die-casting product used in this embodiment of the invention has a Zr composition. 62 Cu 18 Al 10 Ni8Nb 1.5 Y 0.5 The subscript numbers for each element indicate the atomic percentage of that element within the alloy. The amorphous master alloy of the above components was die-cast into a strip-shaped part with a length of 100 mm, a width of 10 mm, and a thickness of 0.3 mm, with an aspect ratio of 10:1. For ease of testing and comparison, the strip-shaped part used in this embodiment is a uniform strip-shaped part.

[0023] In other embodiments, amorphous parts with dimensions of 150 mm in length, 10 mm in width, and 0.3 mm in thickness; 150 mm in length, 15 mm in width, and 0.5 mm in thickness; 100 mm in length, 20 mm in width, and 0.3 mm in thickness; and 100 mm in length, 40 mm in width, and 0.3 mm in thickness were also used, achieving the same technical effects as the embodiments described above. It has been verified that amorphous parts with aspect ratios in the range of 2.5:1 to 15:1 can achieve satisfactory results, especially in thin-walled parts, where they can effectively toughen relatively weak areas.

[0024] The elongated amorphous part in this embodiment is processed as follows: S01, the obtained amorphous alloy die-cast product (long strip-shaped part) is degreased and ultrasonically cleaned to remove surface dirt, and a fixed position is selected as the toughening position to be improved. The length of the toughening position is about 10mm.

[0025] S02, clamp a copper electrode at each end of the selected toughening position, with a distance of about 10mm between the two electrodes. The shape of the copper electrode is adapted to the surface of the amorphous alloy die-cast product being clamped, so that the copper electrode fits the surface of the product being clamped. Then connect the copper electrode to a DC high-voltage power supply.

[0026] The high-voltage DC power supply provides high-voltage DC power. The time accuracy of the high-voltage DC power supply is ±0.1 milliseconds, and the voltage control accuracy is ±0.1V.

[0027] S03, with the power supply set to 265V and the timer set to 140 milliseconds, power was applied and then immediately cut off after heating. At this point, the temperature of the area to be toughened, measured by an infrared thermometer, had reached 460℃ (for this amorphous T). g The temperature is 490℃.

[0028] S04: Dry ice is simultaneously sprayed on both sides of the electrically heated area, causing the temperature of the heated area to rapidly drop below room temperature. Spraying is stopped once the temperature reaches room temperature, as measured by an infrared thermometer.

[0029] S05, the treated amorphous alloy die-cast products are subjected to impact toughness testing, and the test method refers to "GB / T 229-2020 Metallic Materials Charpy Pendulum Impact Test Method".

[0030] S06, products whose toughening areas are black or dark brown after improvement are judged as defective products.

[0031] In this embodiment, a total of 12 samples were improved. Among them, 2 samples showed blackening in the treated areas and were identified as defective products. The untreated amorphous alloy die-cast products were subjected to pendulum tests using the same method, and the test results were compared with those of the treated samples. The test results are shown in the table below.

[0032] Unprocessed #1 - 102.4 Unprocessed #2 - 112.5 Unprocessed #3 - 89.5 Unprocessed #4 - 102.3 Unprocessed #5 - 106.4 Example 1-1# No change 131.5 Example 1-2# No change 121.6 Examples 1-3# No change 135.4 Examples 1-4# No change 141.1 Examples 1-5# No change 123.5 Examples 1-6# No change 149.4 Examples 1-7# black 72.3 Examples 1-8# No change 120.9 Examples 1-9# No change 123.2 Examples 1-10# black 68.5 Example 1-11# No change 132.7 Examples 1-12# No change 124.9 Meanwhile, metallographic tests were also conducted on the areas of the products that showed no change after treatment and the blackened products. Figure 1 Metallographic test results (50x) for products with no change, attached. Figure 2 The results are shown in the metallographic test of the blackened areas (Examples 1-10#). The metallographic test results show that the blackened products have significantly more pores at the test locations than the products where there was no change after improvement. This is because for products with defects such as pores or impurities at the heating location, the resistance at that location increases significantly due to the presence of these defects. During heating, this location undergoes high-temperature oxidation, resulting in discoloration.

[0033] The test results from the embodiments also show that the toughening improvement achieved by the methods described in the embodiments can achieve significant improvement. Example

[0034] In this embodiment, the remaining steps are the same as in Embodiment 1, except that in S03, the power supply is set to 380V and the time is 220 milliseconds. After heating, the power is immediately cut off. At this time, the temperature of the toughening location measured by an infrared thermometer has reached 465℃ (the amorphous T). g The temperature is 490℃.

[0035] Twelve untreated products and twelve treated products were taken from each sample for impact toughness testing. The test results are shown in the table below.

[0036] 1 102.8 130.6 2 131.2 129.4 3 80.2 121.6 4 130.0 154.0 5 105.1 121.0 6 132.4 161.6 7 111.0 123.4 8 112.1 136.2 9 81.3 167.2 10 134.9 131.8 11 95.9 137.9 12 132.4 172.3 The test results from the embodiments also show that the toughening improvement achieved by the methods described in the embodiments can achieve significant improvement.

[0037] As can be seen from the embodiments provided by this invention, the toughness of zirconium-based amorphous products is significantly improved by the process method provided in this invention. The method for improving amorphous toughness provided in this invention is particularly suitable for localized toughening of products with complex structures, without damaging the product surface or causing deformation or other appearance and structural defects. Furthermore, after treatment by the method of this invention, internal pores and heterogeneous point defects in the product appear black or dark brown, allowing for the rapid identification of internally defective products. The amorphous alloy toughening method provided in this invention is simple, efficient, and suitable for large-scale performance improvement and product testing of zirconium-based amorphous products.

[0038] The embodiments described above are merely illustrative of several implementations of the present invention, and while the descriptions are specific and detailed, they should not be construed as limiting the scope of the present invention. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of the present invention, and these modifications and improvements all fall within the scope of protection of the present invention. Therefore, the scope of protection of this patent should be determined by the appended claims.

Claims

1. A method for rapidly improving the local toughness of amorphous alloy die-cast products, characterized in that, The amorphous alloy die-cast product is a long strip-shaped part with an aspect ratio in the range of 2.5:1 to 15:1; The method includes the following steps: S01, Select the toughening location on the amorphous alloy die-cast product that needs improvement; S02, an electrode is clamped at each end of the position to be toughened, and the distance between the two electrodes is in the range of 5mm to 15mm; S03, a high-voltage direct current is applied between the two electrodes to raise the temperature of the location to be toughened from room temperature to 0.92T within 8-500 milliseconds. g ~0.95T g Within the range, the T g The temperature is the glass transition temperature of the amorphous alloy. After heating to the set temperature, the power is immediately cut off. S04, dry ice is sprayed onto the electrically heated position, causing the electrically heated position to rapidly drop below room temperature.

2. The method for rapidly improving the local toughness of amorphous alloy die-cast products according to claim 1, characterized in that, The amorphous alloy is a zirconium-based amorphous alloy, with a zirconium atomic percentage of greater than or equal to 55%.

3. The method for rapidly improving the local toughness of amorphous alloy die-cast products according to claim 1, characterized in that, In S02, the difference between the maximum and minimum cross-sectional areas of the die-cast product between the two clamped electrodes does not exceed 30%.

4. The method for rapidly improving the local toughness of amorphous alloy die-cast products according to claim 1, characterized in that, In S02, the clamped electrode is a copper electrode, and its shape is adapted to the surface of the clamped amorphous alloy die-cast product, so that the copper electrode is in contact with the surface of the clamped product.

5. The method for rapidly improving the local toughness of amorphous alloy die-cast products according to claim 1, characterized in that, In S03, the voltage of the high-voltage direct current is 180V~400V.

6. The method for rapidly improving the local toughness of amorphous alloy die-cast products according to claim 5, characterized in that, In S03, a high-voltage DC power supply is used to provide high-voltage DC power, and the time accuracy of the high-voltage DC power supply is controlled to be ±0.1 milliseconds.

7. The method for rapidly improving the local toughness of amorphous alloy die-cast products according to claim 1, characterized in that, In S04, dry ice is sprayed on both sides of the electrically heated position to cool both sides of the electrically heated position and thus rapidly drop it below room temperature.

8. The method for rapidly improving the local toughness of amorphous alloy die-cast products according to claim 1, characterized in that, The amorphous alloy die-cast products were degreased and ultrasonically cleaned before improvement.

9. The method for rapidly improving the local toughness of amorphous alloy die-cast products according to claim 1, characterized in that, The toughness of the toughening area improved by 10% to 40%.

10. The method for rapidly improving the local toughness of amorphous alloy die-cast products according to any one of claims 1-9, characterized in that, The method is also used to determine whether the amorphous alloy die-cast product has defects. The determination method is as follows: if the toughened area after improvement is black or dark brown, it is determined to be defective.

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