A method for extracting CuTi2 phase

Abstract

This invention relates to the field of metallurgical technology, specifically to a method for extracting the CuTi2 phase. The method comprises the following steps: (a) immersing a Cu-Ti alloy comprising both CuTi and CuTi2 phases in an acid solution, reacting for 2-4 hours, and then washing; (b) immersing the washed Cu-Ti alloy in the acid solution, reacting for 2-4 hours, and then washing; (c) repeating step (b) at least 4 times. The acid solution is prepared by mixing the following components in parts by mass: 0.5-2 parts of 40% hydrofluoric acid, 2-5 parts of 68% nitric acid, 1-3 parts of 37% hydrochloric acid, and 90-98 parts of water. This method can extract the CuTi2 phase.

Description

Technical Field

[0001] This invention relates to the field of metallurgical technology, and more specifically, to a method for extracting the CuTi2 phase. Background Technology

[0002] Cu-Ti alloys exhibit excellent wear resistance, antibacterial properties, and corrosion resistance, making them promising candidates for applications in the biomedical field. Cu-Ti alloys consist of a primary CuTi phase, a primary CuTi2 phase, and a eutectic structure (CuTi + CuTi2). The CuTi2 phase exhibits high hardness and brittleness, typically functioning as a fine second phase to enhance the alloy's strength and wear resistance. However, when the CuTi2 phase appears as coarse grains, it can lead to crack formation and propagation under sustained stress, resulting in material fracture. The microstructure of CuTi2 directly impacts performance, including grain size, growth behavior, and growth mechanism. Therefore, understanding this information about CuTi2 is crucial for further optimizing the performance of Cu-Ti alloys. A common method for characterizing grain size is to statistically analyze it in a two-dimensional plane and calculate the average value. However, the spatial morphology of CuTi2 is not perfectly symmetrical in every spatial direction, leading to uncontrollable errors in this two-dimensional statistical method. Furthermore, growth behavior and mechanisms are also limited by the surrounding microstructure and cannot be fully revealed.

[0003] Therefore, obtaining the three-dimensional morphology of CuTi2 can more accurately determine its spatial dimensions, growth behavior, and growth mechanism, allowing for direct control of the microstructure of CuTi2 from the preparation parameters. This leads to the acquisition of Cu-Ti alloys that meet specific functional and performance requirements, saving subsequent processing costs, which is of great significance.

[0004] Existing techniques use sulfuric acid, hydrogen peroxide solution, or ferric chloride solution to corrode the Cu solid solution in Cu-Ti alloys, retaining the Cu-Ti intermetallic compounds. Alternatively, a mixture of nitric acid and hydrofluoric acid is used to corrode the Ti solid solution in Cu-Ti alloys, retaining the Cu-Ti intermetallic compounds. The key to successful corrosion is the significant difference in corrosion properties between the Cu solid solution (or Ti solid solution) and the Cu-Ti intermetallic compounds. The corrosive solution corrodes rapidly in the Cu solid solution (or Ti solid solution), but reacts very slowly or almost not at all with the Cu-Ti intermetallic compounds. However, the corrosion properties of the Cu-Ti intermetallic compounds are not significantly different. Therefore, extracting a single Cu-Ti intermetallic compound from a Cu-Ti alloy composed of multiple compounds is difficult. No method for extracting a single compound from an alloy composed of multiple Cu-Ti intermetallic compounds has been reported in the prior art.

[0005] In view of this, the present invention is hereby proposed. Summary of the Invention

[0006] The purpose of this invention is to provide a method for extracting the CuTi2 phase, which can extract the CuTi2 phase, overcome the limitations of two-dimensional tissue observation, and realize the analysis of the growth behavior, growth mechanism and quantification of three-dimensional size of CuTi2.

[0007] In order to achieve the above-mentioned objectives of the present invention, the following technical solution is adopted:

[0008] This invention provides a method for extracting the CuTi2 phase, comprising the following steps:

[0009] (a) Immerse the Cu-Ti alloy, whose phase composition includes CuTi phase and CuTi2 phase, in acid solution, react for 2-4 hours, and then wash.

[0010] (b) Immerse the washed Cu-Ti alloy in the acid solution and react for 2-4 hours.

[0011] washing;

[0012] (c) Repeat step (b) at least 4 times;

[0013] The acid solution is prepared by mixing the following components in parts by mass: 0.5 to 2 parts of hydrofluoric acid with a mass fraction of 40%, 2 to 5 parts of nitric acid with a mass fraction of 68%, 1 to 3 parts of hydrochloric acid with a mass fraction of 37%, and 90 to 98 parts of water.

[0014] Further, the acid solution is prepared by mixing the following components in parts by mass: 0.6 to 1.7 parts of hydrofluoric acid with a mass fraction of 40%, 2.8 to 4.2 parts of nitric acid with a mass fraction of 68%, 1.2 to 2.4 parts of hydrochloric acid with a mass fraction of 37%, and 91.7 to 95.4 parts of water.

[0015] Furthermore, each washing cycle is followed by a drying step.

[0016] Furthermore, the washing method includes ultrasonic water washing.

[0017] Furthermore, the washing time for each wash is 10 to 60 minutes.

[0018] Furthermore, after the final washing, the washing liquid is filtered using filter paper with a pore size of 10–15 μm to obtain a filtrate.

[0019] Furthermore, the filtration process further includes a step of drying the filtrate.

[0020] Furthermore, the Cu-Ti alloy is composed of 39.85% to 55.06% Cu and 44.94% to 60.15% Ti by mass percentage.

[0021] Furthermore, in step (a), the Cu-Ti alloy is ground and polished before being immersed in the acid solution.

[0022] Furthermore, the grinding method includes: grinding the Cu-Ti alloy sequentially with 400-grit sandpaper, 800-grit sandpaper, 1200-grit sandpaper, 1500-grit sandpaper and 2000-grit sandpaper; the polishing method includes: polishing with diamond polishing paste.

[0023] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0024] (1) The extraction method provided by the present invention can extract CuTi2 phase, or CuTi2 intermetallic compound, which overcomes the limitations of two-dimensional tissue observation and realizes the observation and analysis of CuTi2 growth behavior, growth mechanism and quantification of three-dimensional size.

[0025] (2) The extraction method of CuTi2 phase provided by the present invention is simple to operate and solves the problem that CuTi phase and CuTi2 phase cannot be extracted separately because their corrosion properties are similar in most corrosive solutions. Attached Figure Description

[0026] To more clearly illustrate the specific embodiments of the present invention or the technical solutions in the prior art, the drawings used in the description of the specific embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of the present invention. For those skilled in the art, other drawings can be obtained from these drawings without creative effort.

[0027] Figure 1 A scanning electron microscope image of the CuTi2 phase obtained in Example 1 of this invention;

[0028] Figure 2 A scanning electron microscope image of the CuTi2 phase obtained in Example 2 of this invention;

[0029] Figure 3 A scanning electron microscope image of the CuTi2 phase obtained in Example 3 of this invention;

[0030] Figure 4 Scanning electron microscope image of the alloy obtained in Comparative Example 1 provided for the present invention;

[0031] Figure 5 Scanning electron microscope image of the alloy obtained in Comparative Example 2 provided for the present invention;

[0032] Figure 6 Scanning electron microscope image of the alloy obtained in Comparative Example 3 provided for the present invention;

[0033] Figure 7 Scanning electron microscope image of the alloy obtained in Comparative Example 4 provided for the present invention;

[0034] Figure 8 Scanning electron microscope image of the alloy obtained in Comparative Example 5 provided for this invention. Detailed Implementation

[0035] The technical solution of the present invention will be clearly and completely described below with reference to the accompanying drawings and specific embodiments. However, those skilled in the art will understand that the embodiments described below are some embodiments of the present invention, but not all embodiments, and are only used to illustrate the present invention, and should not be regarded as limiting the scope of the present invention. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art 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.

[0036] Unless otherwise specified, in this invention, terms such as "first aspect," "second aspect," "third aspect," and "fourth aspect" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or quantity, nor should they be construed as implicitly indicating the importance or quantity of the indicated technical features. Moreover, terms such as "first," "second," "third," and "fourth" serve only as a non-exhaustive enumeration and should be understood not to constitute a closed limitation on quantity.

[0037] Unless otherwise specified, the terms "comprising" and "including" as used in this invention can be open-ended or closed-ended. For example, "comprising" and "including" can mean that other components not listed may also be included, or that only the listed components may be included.

[0038] Unless otherwise specified, in this invention, "one or more" or "at least one" refers to any one, any two, or any two or more of the listed items. "Several" refers to any two or more.

[0039] This invention provides a method for extracting the CuTi2 phase, specifically a method for extracting the three-dimensional morphology of CuTi2, wherein the CuTi2 phase is the primary CuTi2 phase in Cu-Ti alloys. The extraction method includes the following steps:

[0040] (a) Immerse the Cu-Ti alloy, whose phase composition includes CuTi phase and CuTi2 phase, in an acid solution and react for 2–4 hours, then wash. The reaction time in step (a) includes, but is not limited to, any one of 2 hours, 2.5 hours, 3 hours, 3.5 hours, or 4 hours, or a range between any two. Immersion refers to soaking in an acid solution.

[0041] (b) Immerse the washed Cu-Ti alloy in acid solution and react for 2–4 hours, then wash. The reaction time in step (b) includes, but is not limited to, any one of 2 hours, 2.5 hours, 3 hours, 3.5 hours, or 4 hours, or a range between any two. It is understood that in the second and subsequent immersion processes, there is no need to change the acid solution; the acid solution used for the first immersion can be reused.

[0042] (c) Repeat step (b) at least 4 times. The number of times step (b) is repeated is at least 4 times, for example, 5 times, 6 times, 7 times, or 8 times.

[0043] The acid solution is prepared by mixing the following components in parts by mass: 0.5 to 2 parts of hydrofluoric acid (40% by mass), 2 to 5 parts of nitric acid (68% by mass), 1 to 3 parts of hydrochloric acid (37% by mass), and 90 to 98 parts of water. The mass fractions of hydrofluoric acid include, but are not limited to, any one of the following values ​​or any range between two: 0.5 parts, 0.8 parts, 1 part, 1.2 parts, 1.3 parts, 1.5 parts, 1.8 parts, and 2 parts; the mass fractions of nitric acid include, but are not limited to, any one of the following values ​​or any range between two: 2 parts, 2.5 parts, 3 parts, 3.5 parts, 4 parts, 4.5 parts, and 5 parts; the mass fractions of hydrochloric acid include, but are not limited to, any one of the following values ​​or any range between two: 1 part, 1.2 parts, 1.3 parts, 1.5 parts, 1.8 parts, 2 parts, 2.3 parts, 2.5 parts, 2.8 parts, and 3 parts; and the mass fractions of water include, but are not limited to, any one of the following values ​​or any range between two: 90 parts, 91 parts, 92 parts, 93 parts, 94 parts, 95 parts, 96 parts, 97 parts, and 98 parts.

[0044] In the aforementioned acid solution, the CuTi2 phase in the Cu-Ti alloy exhibits strong corrosion resistance and hardly reacts with the acid solution within 2–4 hours. However, the CuTi phase has poor corrosion resistance in this acid solution and is largely corroded away after being immersed in the corrosive solution for 2 hours. Therefore, the almost unreacted primary CuTi2 phase is completely exposed due to the corrosion of the surrounding CuTi phase.

[0045] The purpose of washing after each acid immersion is to remove corrosion products from the surface of the Cu-Ti alloy. Because the corrosion products generated after a period of reaction will cover the entire surface of the Cu-Ti alloy, preventing direct contact with the acid and causing the reaction to stop, the washing, reaction, and washing process needs to be repeated multiple times.

[0046] The material obtained after multiple corrosion reactions, when observed under a scanning electron microscope, is a separate CuTi2 phase, or CuTi2 compound.

[0047] The method for extracting CuTi2 phase provided by this invention overcomes the limitations of two-dimensional tissue observation and enables the analysis of CuTi2 growth behavior, growth mechanism and quantification of three-dimensional size.

[0048] The CuTi2 phase extraction method provided by this invention is simple to operate and solves the problem that CuTi and CuTi2 phases cannot be extracted separately because their corrosive properties are similar in most corrosive solutions.

[0049] In some specific embodiments, in order to further improve the extraction efficiency, the acid solution is prepared by mixing the following components in parts by mass: 0.6 to 1.7 parts of hydrofluoric acid with a mass fraction of 40%, 2.8 to 4.2 parts of nitric acid with a mass fraction of 68%, 1.2 to 2.4 parts of hydrochloric acid with a mass fraction of 37%, and 91.7 to 95.4 parts of water.

[0050] In some specific embodiments, the water includes deionized water.

[0051] In some specific embodiments, a drying step is also included after each washing. Drying can prevent residual water or other detergents on the Cu-Ti alloy surface from entering the acid solution and causing changes in the acid concentration.

[0052] In some specific implementations, after each washing, filtration and drying are performed sequentially.

[0053] In some specific embodiments, the washing method for each wash includes ultrasonic water washing. That is, ultrasonic cleaning is performed using deionized water.

[0054] In some specific embodiments, the washing time for each wash is 10 to 60 minutes, including but not limited to any one of 10 minutes, 20 minutes, 30 minutes, 40 minutes, 50 minutes, and 60 minutes, or any range between two of them.

[0055] In some specific embodiments, after the final wash, the washing liquid obtained after the final wash is filtered using filter paper with a pore size of 10–15 μm to obtain a filtrate. This filtrate contains a CuTi2 phase.

[0056] It is understandable that the filter paper with a pore size of 10-15μm mentioned above refers to a filter paper with a pore size specification of 10-15μm.

[0057] In some specific embodiments, the filtration process further includes a step of drying the filtrate to obtain the CuTi2 phase. The drying temperature can be any commonly used drying temperature, for example, 80–100°C, but is not limited thereto.

[0058] In some specific embodiments, the Cu-Ti alloy comprises 39.85% to 55.06% Cu and 44.94% to 60.15% Ti by mass percentage. The mass percentage of Cu includes, but is not limited to, any one of 39.85%, 40%, 43%, 45%, 48%, 50%, 53%, and 55.06%, or a range between any two. The mass percentage of Ti includes, but is not limited to, any one of 44.94%, 45%, 48%, 50%, 53%, 55%, 58%, 60%, and 60.15%, or a range between any two. It is understood that the sum of the mass percentages of Cu and Ti is 100%.

[0059] In some specific embodiments, in step (a), the Cu-Ti alloy is ground and polished before immersion in the acid solution. Grinding and polishing remove the oxide scale generated during processing, ensuring that the sample used is a Cu-Ti alloy, guaranteeing successful extraction of the CuTi2 phase, and improving extraction efficiency.

[0060] In some specific embodiments, the polishing method includes: sequentially polishing the Cu-Ti alloy with 400-grit sandpaper, 800-grit sandpaper, 1200-grit sandpaper, 1500-grit sandpaper, and 2000-grit sandpaper.

[0061] In some specific embodiments, the polishing process includes polishing with diamond polishing paste.

[0062] In some specific embodiments, in step (a), the Cu-Ti alloy comprises a blocky Cu-Ti alloy with a length, width, and height of 4–6 mm, 4–6 mm, and 2–4 mm, respectively. The extraction of the CuTi2 phase is preferably performed using a cubic Cu-Ti alloy. That is, the shape of the Cu-Ti alloy includes cubic shapes, such as cuboids. However, it is not limited to this, and other shapes of Cu-Ti alloys can also be used.

[0063] The embodiments of the present invention will be described in detail below with reference to examples. However, those skilled in the art will understand that the following examples are for illustrative purposes only and should not be considered as limiting the scope of the invention. Unless otherwise specified in the examples, conventional conditions or conditions recommended by the manufacturer are followed. Reagents or instruments whose manufacturers are not specified are all commercially available conventional products.

[0064] Example 1

[0065] The CuTi2 phase extraction method provided in this embodiment includes the following steps:

[0066] (1) Take a cubic Cu-Ti alloy with a length × width × height of 5mm × 5mm × 3mm. The Cu-Ti alloy is composed of 54% Cu and 46% Ti by mass percentage. The Cu-Ti alloy includes CuTi phase and CuTi2 phase. The surfaces of the Cu-Ti alloy are polished sequentially with 400 grit sandpaper, 800 grit sandpaper, 1200 grit sandpaper, 1500 grit sandpaper and 2000 grit sandpaper, and polished with 0.25μm diamond polishing paste. Then, it is ultrasonically cleaned with deionized water and dried.

[0067] (2) The polished Cu-Ti alloy obtained in step (1) is immersed in an acid solution, which is prepared by mixing the following components in parts by mass: 1.2 parts of hydrofluoric acid (40% by mass), 3.5 parts of nitric acid (68% by mass), 1.8 parts of hydrochloric acid (37% by mass), and 93.5 parts of deionized water. After immersion and reaction for 2 hours, the Cu-Ti alloy is removed and ultrasonically cleaned with deionized water for 10 minutes to remove corrosion products on the surface of the metal block, and then dried.

[0068] (3) The dried Cu-Ti alloy obtained in step (2) was further immersed in acid solution. After reacting for 2 hours, it was removed, ultrasonically cleaned with deionized water for 10 minutes, and then dried. The immersion-ultrasonic water washing-drying steps were repeated 4 times. After the last water washing, the water washing solution was filtered with filter paper with a pore size of 10-15 μm to obtain the filtrate. The filtrate was then dried to obtain the CuTi2 phase. The CuTi2 phase was observed under a scanning electron microscope. Figure 1 As shown, it can be seen that it is a separate CuTi2 phase, and its three-dimensional morphology can be observed.

[0069] Example 2

[0070] The CuTi2 phase extraction method provided in this embodiment includes the following steps:

[0071] (1) Take a cubic Cu-Ti alloy with a length × width × height of 5mm × 5mm × 3mm. The Cu-Ti alloy is composed of 54% Cu and 46% Ti by mass percentage. The Cu-Ti alloy includes CuTi phase and CuTi2 phase. The surfaces of the Cu-Ti alloy are polished sequentially with 400 grit sandpaper, 800 grit sandpaper, 1200 grit sandpaper, 1500 grit sandpaper and 2000 grit sandpaper, and polished with 0.25μm diamond polishing paste. Then, it is ultrasonically cleaned with deionized water and dried.

[0072] (2) The polished Cu-Ti alloy obtained in step (1) was immersed in an acid solution, which was prepared by mixing the following components in parts by mass: 1.7 parts of hydrofluoric acid (40% by mass), 4.2 parts of nitric acid (68% by mass), 2.4 parts of hydrochloric acid (37% by mass), and 91.7 parts of deionized water. After immersion and reaction for 2 hours, the Cu-Ti alloy was removed and ultrasonically cleaned with deionized water for 10 minutes to remove corrosion products on the surface of the metal block, and then dried.

[0073] (3) The dried Cu-Ti alloy obtained in step (2) was further immersed in acid solution. After reacting for 2 hours, it was removed, ultrasonically cleaned with deionized water for 10 minutes, and then dried. The immersion-ultrasonic water washing-drying steps were repeated 4 times. After the last water washing, the water washing solution was filtered with filter paper with a pore size of 10-15 μm to obtain the filtrate. The filtrate was then dried to obtain the CuTi2 phase. The CuTi2 phase was observed under a scanning electron microscope. Figure 2 As shown, it can be seen that it is a separate CuTi2 phase, and its three-dimensional morphology can be observed.

[0074] Example 3

[0075] The CuTi2 phase extraction method provided in this embodiment includes the following steps:

[0076] (1) Take a cubic Cu-Ti alloy with a length × width × height of 5mm × 5mm × 3mm. The Cu-Ti alloy is composed of 52.5% Cu and 47.5% Ti by mass percentage. The Cu-Ti alloy includes CuTi phase and CuTi2 phase. The surfaces of the Cu-Ti alloy are polished with 400 grit sandpaper, 800 grit sandpaper, 1200 grit sandpaper, 1500 grit sandpaper and 2000 grit sandpaper in sequence, and polished with 0.25μm diamond polishing paste. Then, it is ultrasonically cleaned with deionized water and dried.

[0077] (2) The polished Cu-Ti alloy obtained in step (1) was immersed in an acid solution, which was prepared by mixing the following components in parts by mass: 0.6 parts of hydrofluoric acid (40% by mass), 2.8 parts of nitric acid (68% by mass), 1.2 parts of hydrochloric acid (37% by mass), and 95.4 parts of deionized water. After immersion and reaction for 2 hours, the Cu-Ti alloy was removed and ultrasonically cleaned with deionized water for 10 minutes to remove corrosion products on the surface of the metal block, and then dried.

[0078] (3) The dried Cu-Ti alloy obtained in step (2) was further immersed in acid solution for 2 hours. After that, it was taken out, ultrasonically cleaned with deionized water for 20 minutes, and then dried. The immersion-ultrasonic water washing-drying steps were repeated 4 times. After the last water washing, the water washing solution was filtered with filter paper with a pore size of 10-15 μm to obtain the filtrate. The filtrate was then dried to obtain the CuTi2 phase. The CuTi2 phase was observed under a scanning electron microscope. Figure 3 As shown, it can be seen that it is a separate CuTi2 phase, and its three-dimensional morphology can be observed.

[0079] Example 4

[0080] The extraction method of CuTi2 phase provided in this embodiment is basically the same as that in Example 1. The difference is that the chemical composition of the Cu-Ti alloy used in step (1) is different. The Cu-Ti alloy used in this embodiment is composed of 52% Cu and 48% Ti by mass percentage.

[0081] Example 5

[0082] The extraction method of CuTi2 phase provided in this embodiment is basically the same as that in Example 1. The difference is that the steps of soaking-ultrasonic washing-drying are repeated 5 times in step (3).

[0083] Example 6

[0084] The extraction method of CuTi2 phase provided in this embodiment is basically the same as that in Example 1, except that the soaking time is 4 hours each time, that is, the reaction time is 4 hours each time.

[0085] Comparative Example 1

[0086] The extraction method of CuTi2 phase provided in this comparative example is basically the same as that in Example 1, except that the hydrofluoric acid in the acid solution is replaced with an equal mass of nitric acid. That is, the acid solution is prepared by mixing the following components in parts by mass: 4.7 parts of nitric acid with a mass fraction of 68%, 1.8 parts of hydrochloric acid with a mass fraction of 37%, and 93.5 parts of deionized water.

[0087] The scanning electron microscope image of the alloy finally obtained in this comparative example is as follows: Figure 4As shown, the Cu-Ti alloy exhibits good corrosion resistance in the acid solution of this comparative example. Only a small number of corrosion pits appeared on the surface of the Cu-Ti alloy, and a large amount of CuTi phase was not corroded away. Therefore, the CuTi2 phase could not be extracted.

[0088] Comparative Example 2

[0089] The extraction method of CuTi2 phase provided in this comparative example is basically the same as that in Example 1, except that the nitric acid in the acid solution is replaced with an equal mass of hydrochloric acid. That is, the acid solution is prepared by mixing the following components in parts by mass: 1.2 parts of hydrofluoric acid with a mass fraction of 40%, 5.3 parts of hydrochloric acid with a mass fraction of 37%, and 93.5 parts of deionized water.

[0090] The scanning electron microscope image of the alloy finally obtained in this comparative example is as follows: Figure 5 As shown, the corrosiveness of the etching solution is insufficient to completely remove the CuTi phase. A mixture of unreacted CuTi phase and corrosion products remains around the CuTi2 phase, so the CuTi2 phase cannot be extracted separately.

[0091] Comparative Example 3

[0092] The extraction method of CuTi2 phase provided in this comparative example is basically the same as that in Example 1, except that the hydrochloric acid in the acid solution is replaced with an equal mass of hydrofluoric acid. That is, the acid solution is prepared by mixing the following components in parts by mass: 3 parts of hydrofluoric acid with a mass fraction of 40%, 3.5 parts of nitric acid with a mass fraction of 68%, and 93.5 parts of deionized water.

[0093] The scanning electron microscope image of the alloy finally obtained in this comparative example is as follows: Figure 6 As shown, the Cu-Ti alloy exhibits good corrosion resistance in the acid solution of this comparative example. Only a small number of corrosion pits appeared on the surface of the Cu-Ti alloy, and differential corrosion between the CuTi phase and CuTi2 phase could not be achieved, thus failing to obtain a separate CuTi2 phase.

[0094] Comparative Example 4

[0095] The extraction method for the CuTi2 phase provided in this comparative example is basically the same as that in Example 1, except that the acid solution is prepared by mixing the following components in parts by mass: 5 parts of hydrofluoric acid (40% by mass), 8 parts of nitric acid (68% by mass), 5 parts of hydrochloric acid (37% by mass), and 82 parts of deionized water. The scanning electron microscope image of the alloy finally obtained in this comparative example is shown below. Figure 7 As shown, it can be seen that due to the excessive acid concentration, the CuTi2 phase, which was originally resistant to corrosion, also began to be corroded, losing its selective corrosion effect.

[0096] Comparative Example 5

[0097] The extraction method of CuTi2 phase provided in this comparative example is basically the same as that in Example 1, except that the soaking time is 8 hours each time, that is, the reaction time is 8 hours each time.

[0098] The scanning electron microscope image of the alloy finally obtained in this comparative example is as follows: Figure 8 As shown, due to the excessively long corrosion time, more corrosion products are generated, and these products accumulate on the surface of the alloy, affecting subsequent corrosion. The large amount of corrosion products formed may be due to secondary corrosion, resulting in a large number of water-insoluble corrosion products that cannot be washed away, thus making it impossible to obtain a separate CuTi2 phase.

[0099] Although the present invention has been illustrated and described with specific embodiments, it should be understood that the above embodiments are only used to illustrate the technical solutions of the present invention, and not to limit them; those skilled in the art should understand that modifications can be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some or all of the technical features therein, without departing from the spirit and scope of the present invention; and these modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention; therefore, this means that all such substitutions and modifications that fall within the scope of the present invention are included in the appended claims.

Claims

1. A method for extracting the CuTi2 phase, characterized in that, Includes the following steps: (a) Immerse the Cu-Ti alloy, whose phase composition includes CuTi phase and CuTi2 phase, in acid solution, react for 2-4 hours, and then wash. (b) Immerse the washed Cu-Ti alloy in the acid solution and react for 2-4 hours, then wash. (c) Repeat step (b) at least 4 times; The acid solution is prepared by mixing the following components in parts by mass: 0.5 to 2 parts of hydrofluoric acid with a mass fraction of 40%, 2 to 5 parts of nitric acid with a mass fraction of 68%, 1 to 3 parts of hydrochloric acid with a mass fraction of 37%, and 90 to 98 parts of water.

2. The method for extracting the CuTi2 phase according to claim 1, characterized in that, The acid solution is prepared by mixing the following components in parts by mass: 0.6 to 1.7 parts of hydrofluoric acid with a mass fraction of 40%, 2.8 to 4.2 parts of nitric acid with a mass fraction of 68%, 1.2 to 2.4 parts of hydrochloric acid with a mass fraction of 37%, and 91.7 to 95.4 parts of water.

3. The method for extracting the CuTi2 phase according to claim 1, characterized in that, Each washing cycle is followed by a drying step.

4. The method for extracting the CuTi2 phase according to claim 1, characterized in that, The washing method includes ultrasonic water washing.

5. The method for extracting the CuTi2 phase according to claim 1, characterized in that, Each wash session lasts 10 to 60 minutes.

6. The method for extracting the CuTi2 phase according to claim 1, characterized in that, After the final washing, the washing liquid is filtered using filter paper with a pore size of 10–15 μm to obtain the filtrate.

7. The method for extracting the CuTi2 phase according to claim 6, characterized in that, The filtration process also includes a step of drying the filtrate.

8. The method for extracting the CuTi2 phase according to claim 1, characterized in that, The Cu-Ti alloy consists of 39.85% to 55.06% Cu and 44.94% to 60.15% Ti by mass percentage.

9. The method for extracting the CuTi2 phase according to claim 1, characterized in that, In step (a), the Cu-Ti alloy is ground and polished before being immersed in the acid solution.

10. The method for extracting the CuTi2 phase according to claim 9, characterized in that, The polishing method includes: sequentially polishing the Cu-Ti alloy with 400-grit sandpaper, 800-grit sandpaper, 1200-grit sandpaper, 1500-grit sandpaper, and 2000-grit sandpaper; The polishing method includes polishing with diamond polishing paste.

Images