Nickel-copper alloy and preparation method thereof

Abstract

The invention discloses a nickel-copper alloy and a preparation method thereof. The method comprises the following steps: preparing an electrolytic copper plate, a nickel plate and a strengthening phase in proportion; the strengthening phase is put into a smelting furnace to be smelted, and then the electrolytic copper plate and the nickel plate are put into the smelting furnace to be smelted, so that a nickel-copper alloy melt is obtained; adding a reducing agent and a slag former into the nickel-copper alloy melt to purify the nickel-copper alloy melt; inert gas is introduced into the purified nickel-copper alloy melt, and rare earth elements are added into the purified nickel-copper alloy melt; casting the nickel-copper alloy melt added with the rare earth elements to obtain a nickel-copper alloy; and the nickel-copper alloy is subjected to electroslag remelting, and the final nickel-copper alloy is obtained after cooling. The overall performance of the nickel-copper alloy can be improved.

Description

Technical Field

[0001] The present application belongs to the technical field of alloy preparation, and specifically relates to a nickel-copper alloy and a preparation method thereof. Background Art

[0002] Nickel-copper alloys are widely used in aerospace, electronics manufacturing, automotive industry, marine engineering and other fields. However, the existing nickel-copper alloy preparation method usually simply sintered nickel and copper, resulting in the presence of shrinkage, looseness and pores in the prepared nickel-copper alloy, which significantly reduced the strength and corrosion resistance of the nickel-copper alloy. Summary of the invention

[0003] In view of the deficiencies in the prior art, the purpose of the present application is to provide a nickel-copper alloy and a preparation method thereof, which can improve the overall performance of the nickel-copper alloy.

[0004] To achieve the above objectives, this application provides the following technical solutions:

[0005] A method for preparing a nickel-copper alloy comprises: preparing an electrolytic copper plate, a nickel plate and a strengthening phase in proportion; firstly putting the strengthening phase into a smelting furnace for smelting, and then putting the electrolytic copper plate and the nickel plate into the smelting furnace for smelting to obtain a nickel-copper alloy melt; adding a reducing agent and a slag-forming agent into the nickel-copper alloy melt to purify the nickel-copper alloy melt; introducing an inert gas into the purified nickel-copper alloy melt and adding rare earth elements; casting the nickel-copper alloy melt after adding the rare earth elements to obtain a nickel-copper alloy; and electroslag remelting the nickel-copper alloy to obtain a final nickel-copper alloy after cooling.

[0006] Optionally, the strengthening phase includes any one of the following: tin alloy, aluminum alloy and manganese alloy.

[0007] Optionally, the electrolytic copper plate, nickel plate and strengthening phase need to be cleaned and preheated before smelting.

[0008] Optionally, during the smelting process, the temperature of the smelting furnace needs to be controlled to be 200° C. higher than the melting point of the nickel-copper alloy.

[0009] Optionally, the reducing agent includes any one of the following: charcoal, aluminum powder and titanium powder.

[0010] Optionally, the slag-forming agent includes any one of the following: calcium fluoride, magnesium fluoride and lithium fluoride.

[0011] Optionally, the rare earth element includes any one of the following: lanthanum, cerium and neodymium.

[0012] Optionally, vibration casting is adopted for the nickel-copper alloy melt after rare earth elements are added.

[0013] In addition, the present application also provides a nickel-copper alloy, the components of the nickel-copper alloy and the content of each component include: copper: 50-70%, nickel: 20-40%, and strengthening phase: 1-10%.

[0014] In addition, the present application also provides a turbine blade for an engine, wherein the turbine blade is made of the nickel-copper alloy as described above.

[0015] Compared with the prior art, the present invention has the following beneficial effects:

[0016] The present application provides a nickel-copper alloy and a preparation method thereof, which significantly improves the mechanical properties and corrosion resistance of the nickel-copper alloy by optimizing key steps such as raw material ratio, smelting process, purification treatment and electroslag remelting. The nickel-copper alloy prepared by this method is significantly superior to the nickel-copper alloy prepared by the existing method in multiple performance indicators such as tensile strength, elongation, impact toughness, grain size, density, purity, corrosion resistance and oxidation resistance. In particular, the electroslag remelting process further improves the purity and microstructure uniformity of the alloy, reduces pores and inclusions, and makes the final product have higher density and better comprehensive performance, which is suitable for high-demand industrial fields. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Figure 1 It is a schematic flow chart of a method for preparing a nickel-copper alloy provided in one embodiment of the present application;

[0018] Figure 2 It is CuNi provided in another embodiment of the present application 44 Metallographic diagram of M1 nickel-copper alloy;

[0019] Figure 3 It is CuNi provided in another embodiment of the present application 30 Metallographic diagram of Al2 nickel-copper alloy. DETAILED DESCRIPTION

[0020] The specific embodiments of the present application will be described in detail below with reference to the accompanying drawings. Although the specific embodiments of the present application are shown in the accompanying drawings, it should be understood that the present application can be implemented in various forms and should not be limited by the embodiments set forth herein. On the contrary, these embodiments are provided in order to enable a more thorough understanding of the present application and to fully convey the scope of the present application to those skilled in the art.

[0021] It should be noted that certain words are used in the specification and claims to refer to specific components. Those skilled in the art should understand that technicians may use different nouns to refer to the same component. This specification and claims do not use the difference in nouns as a way to distinguish components, but use the difference in the functions of the components as the criterion for distinction. As mentioned throughout the specification and claims, "including" or "comprising" is an open term, so it should be interpreted as "including but not limited to". The subsequent description of the specification is a preferred embodiment of the implementation of the present application, but the description is based on the general principles of the specification and is not used to limit the scope of the present application. The scope of protection of the present application shall be determined by the attached claims.

[0022] To facilitate understanding of the embodiments of the present application, further explanation will be given below using specific embodiments as examples in conjunction with the accompanying drawings, and the various drawings do not constitute a limitation on the embodiments of the present application.

[0023] Figure 1 FIG. 1 is a schematic flow chart of a method for preparing a nickel-copper alloy provided in one embodiment of the present application. Figure 1 As shown, the preparation method comprises the following steps:

[0024] S1: preparing electrolytic copper plates, nickel plates and tin alloys in proportions of 50-70%, 20-40% and 1-10%, and cleaning and preheating the electrolytic copper plates, nickel plates and tin alloys;

[0025] In this step, during the preparation of the nickel-copper alloy, the tin element is easily burned or volatilized under high temperature conditions, which not only causes the loss of the tin element, but also affects the uniform distribution of the tin element in the nickel-copper alloy. In order to solve this problem, the present application adopts the method of adding the tin element in the form of an alloy (specifically, a metal that is not easy to volatilize and can be well combined with tin is alloyed with tin, such as a tin-copper alloy or a tin-lead alloy).

[0026] It should be noted that compared with directly adding tin, the advantages of using tin alloys are: First, protecting the tin element: tin is an element that is easy to burn or volatilize. By pre-making the tin element into a tin alloy, the tin element can be protected from direct exposure to high temperature environment to a certain extent, thereby reducing its burning and volatilization; second, improving the uniformity of composition: the tin alloy is already in a relatively uniform state when added to the main melt, which helps to improve the uniformity of the distribution of tin in the nickel-copper alloy; third, it can simplify the process: compared with directly adding a single tin element, the use of tin alloys can simplify the feeding process and make it easier to control the amount of addition and the composition ratio of the nickel-copper alloy.

[0027] It should also be noted that this step uses electrolytic copper plates and nickel plates instead of directly using copper powder and nickel powder, mainly based on the following considerations:

[0028] First, compared with copper powder and nickel powder, electrolytic copper plates and nickel plates usually have higher purity. Electrolytic copper plates are obtained through electrolytic refining, and the purity can reach more than 99.9%, while nickel plates are also high-purity nickel obtained through a similar refining process. The use of high-purity raw materials can ensure the purity of the final alloy and reduce the impact of impurities, thereby improving the mechanical properties and corrosion resistance of nickel-copper alloys.

[0029] Second, electrolytic copper plates and nickel plates are easier to handle and process than copper powder and nickel powder. The shapes and sizes of electrolytic copper plates and nickel plates are relatively fixed, which is convenient for weighing and adding to the smelting furnace. It is also easier to control the amount added during the smelting process, thereby ensuring the accuracy of the nickel-copper alloy composition.

[0030] In addition, by cleaning the electrolytic copper plate, nickel plate and tin alloy, firstly, surface pollutants such as dust, grease, moisture, etc. can be removed, thereby improving the purity and corrosion resistance of the nickel-copper alloy; secondly, it helps the materials to melt faster and mix evenly during the smelting process (surface pollutants will hinder the melting of materials, prolong the smelting time, and increase energy consumption); thirdly, it can prevent the oxidation of materials (the oxygen elements in the surface pollutants may react with the metal at high temperature to form oxides, which will not only affect the purity of the alloy, but also form defects in the alloy, reducing the mechanical properties and corrosion resistance of the alloy).

[0031] Furthermore, preheating can make the material reach a certain temperature before entering the melting furnace, reducing the temperature difference between the material and the melting furnace, helping to reduce the generation of thermal stress and prevent cracks or other defects in the material during the heating process. If the material is heated directly from room temperature to high temperature, the large temperature difference between the inside and outside will cause greater thermal stress inside the material, which may cause the material to crack or deform. In addition, preheating can make the material at a higher temperature when entering the melting furnace, which helps the material reach the melting temperature faster during the melting process, thereby achieving more uniform melting and mixing, and ensuring uniform distribution of alloy components.

[0032] S2: First, add the tin alloy into the smelting furnace for smelting. When the temperature of the smelting furnace rises to the temperature at which the tin alloy is completely melted (about 200-250°C), continue to heat up. When the furnace temperature reaches a temperature at which the electrolytic copper plate and the nickel plate begin to melt (usually above 1000°C), add the electrolytic copper plate and the nickel plate for smelting to obtain a nickel-copper alloy melt containing tin element.

[0033] In this step, the reason why the tin alloy is first added to the smelting furnace for smelting is that: first, the melting point of the tin alloy is lower than that of the electrolytic copper plate and the nickel plate, and the tin alloy can be melted first at a lower temperature, so that a good liquid environment can be formed, which is conducive to the subsequent addition of higher melting point materials (such as nickel plate and electrolytic copper plate) to dissolve into the molten pool faster, thereby accelerating the entire smelting process; second, when the tin alloy is melted first, it can be used as a "solvent" to promote the mutual dissolution and diffusion between the nickel plate and the electrolytic copper plate, which is conducive to ensuring the uniformity of the final alloy composition, thereby avoiding the situation where local uneven composition leads to insufficient alloying in certain areas; third, the furnace starts to heat up gradually from a low temperature and adds raw materials with different melting points in stages, which helps to alleviate the thermal stress problem caused by rapid heating (if directly heated at high temperature In the case of hot nickel plates and electrolytic copper plates, in a high temperature environment, the outer layer of the nickel plates and electrolytic copper plates may have melted while the inner layer is still in a solid state, which will lead to a large temperature difference between the inside and outside, thereby generating a large thermal stress. Adding tin alloy first to melt it can provide a relatively mild thermal environment for the nickel plates and electrolytic copper plates added later, thereby avoiding local overheating), thereby reducing the probability of internal defects (such as cracks) in the alloy (during the heating process, if the temperature rises too quickly, a significant temperature gradient will be formed inside the raw material, resulting in inconsistent expansion or contraction of different parts. This inconsistency will generate internal stress, which may cause the raw material to crack in severe cases. Adding raw materials with different melting points in stages can make the overall temperature distribution more uniform, reduce the temperature gradient, and thus reduce the internal stress caused by thermal expansion and contraction).

[0034] It should be noted that if a high-melting-point nickel plate or electrolytic copper plate is added at the beginning, the nickel plate or electrolytic copper plate will react with the oxygen in the furnace atmosphere to generate oxides during the heating process to its melting point. In addition, if a low-melting-point tin alloy and a high-melting-point nickel plate or electrolytic copper plate are put in at one time and quickly heated to a high temperature, non-uniform solidification will result, thereby increasing the risk of defects such as central porosity and pores in the nickel-copper alloy. The present application first adds the tin alloy and partially or completely melts it, and then gradually adds the electrolytic copper plate and the nickel plate. First, this oxidation phenomenon can be reduced to a certain extent, because the existing liquid can provide a better protective layer and can cover the newly added solid particles more quickly; second, in the continuous casting process, reasonable temperature control can make the melt cool and crystallize in an orderly manner from the outside to the inside, which helps to form a dense microstructure without obvious defects.

[0035] S3: adding charcoal and calcium fluoride to the nickel-copper alloy melt containing tin element in sequence, and controlling the temperature in the smelting furnace to be 200° C. higher than the melting point of the nickel-copper alloy;

[0036] In this step, the role of charcoal is mainly as a reducing agent. At high temperature, charcoal can react with oxygen in the nickel-copper alloy melt to generate carbon dioxide (CO2) to escape, which helps to reduce oxide inclusions in the nickel-copper alloy melt, thereby improving the purity of the nickel-copper alloy.

[0037] The role of calcium fluoride (CaF2) is mainly reflected in two aspects: first, as a slag-forming agent, calcium fluoride can help form a slag with good fluidity. This slag can absorb and encapsulate non-metallic inclusions and gases in the nickel-copper alloy melt, which helps to purify the nickel-copper alloy melt to improve the purity and density of the nickel-copper alloy; secondly, calcium fluoride can also lower the melting point of the slag, so that the slag maintains good fluidity and stability at a lower temperature, thereby helping to remove harmful impurities in the nickel-copper alloy melt.

[0038] In summary, by adding charcoal and calcium fluoride in this step, the purity of the nickel-copper alloy melt can be improved, oxides and other harmful impurities can be reduced, thereby ensuring that the final nickel-copper alloy has excellent mechanical properties and corrosion resistance.

[0039] It should be noted that in this step, the temperature in the smelting furnace needs to be controlled at 200°C higher than the melting point of the nickel-copper alloy. For example, if the melting point of the nickel-copper alloy is between 1200°C and 1300°C, the temperature in the smelting furnace should be controlled at between 1400°C and 1500°C. The reason for this is that the melting point of the nickel-copper alloy is usually between 1200°C and 1300°C. Controlling the temperature in the smelting furnace at 200°C higher than the melting point of the nickel-copper alloy (i.e., 1400°C to 1500°C) can ensure that all alloy components are completely melted to form a uniform alloy solution, thereby avoiding any unmelted solid particles remaining in the melt.

[0040] It should also be noted that if the temperature in the smelting furnace is controlled to be lower than the melting point of the nickel-copper alloy by 200°C, some alloy components may not be completely melted, and thus remain in the nickel-copper alloy melt, resulting in uneven composition, which ultimately affects the performance of the nickel-copper alloy. Moreover, if the temperature is lower than 200°C, the charcoal will not react fully with the oxygen in the melt, and the oxides in the melt cannot be effectively removed, which affects the purity of the nickel-copper alloy. At the same time, calcium fluoride cannot form a slag with good fluidity, and cannot effectively adsorb and encapsulate non-metallic inclusions and gases in the melt, which will affect the purity and density of the nickel-copper alloy. In addition, since the tin element is easy to volatilize at high temperatures, if the temperature is higher than 200°C, the tin element will volatilize in large quantities, resulting in uneven alloy composition, which will affect the performance of the nickel-copper alloy.

[0041] S4: maintaining the temperature in the smelting furnace higher than the melting point of the nickel-copper alloy by 200° C., and introducing argon gas to help gases (especially hydrogen and oxygen) escape from the smelting furnace to reduce the formation of pores and bubbles, and adding a small amount of lanthanum (La) (accounting for 0.01% to 0.1% of the total weight of the nickel-copper alloy, for example, the total weight of the nickel-copper alloy is 1000 kg, and the amount of lanthanum added is between 100 grams and 1000 grams) 5 minutes before the nickel-copper alloy melt is taken out of the furnace;

[0042] In this step, the alloy melting point refers to the temperature at which the nickel-copper alloy begins to melt. For example, the melting point of the nickel-copper alloy may be between 1200°C and 1300°C, and the temperature in the smelting furnace needs to be increased to between 1400°C and 1500°C, which helps to ensure the fusion and uniform mixing of the alloy solution, and also helps to remove gases and impurities in the melt.

[0043] In addition, on the basis of introducing argon gas into the smelting furnace, the present embodiment further adds an appropriate amount of CuMg alloy. The magnesium (Mg) in the CuMg alloy has a strong deoxidation ability. When the CuMg alloy is added to the nickel-copper alloy melt, the magnesium (Mg) will react with the oxygen in the melt to generate magnesium oxide (MgO). The magnesium oxide will form slag floating on the surface of the melt, which will be removed, thereby further improving the purity of the nickel-copper alloy.

[0044] It should be noted that lanthanum (La), as a rare earth element, has a strong grain refining effect. Lanthanum atoms are preferentially precipitated at the grain boundaries during solidification to form fine second-phase particles. These particles can serve as crystal nuclei, increase the number of crystal nuclei, and thus refine the grains. Refining the grains can improve the strength, plasticity and toughness of the nickel-copper alloy, thereby improving the comprehensive mechanical properties of the nickel-copper alloy. In addition, the addition of lanthanum (La) can also promote the uniform distribution of each component in the nickel-copper alloy, reduce segregation, and make the microstructure of the nickel-copper alloy more uniform. The uniform microstructure can improve the mechanical properties and corrosion resistance of the nickel-copper alloy.

[0045] It should also be noted that the reason why a small amount of lanthanum (La) is added 5 minutes before the nickel-copper alloy melt is discharged from the furnace is that lanthanum (La) is a highly active rare earth element. If it is added too early, it will over-react with other elements in the melt during the smelting process to generate too many compounds, thereby affecting the purity and performance of the nickel-copper alloy. In addition, adding lanthanum 5 minutes before the nickel-copper alloy melt ensures that lanthanum (La) has enough time to be evenly distributed in the nickel-copper alloy melt, thereby maximizing the promotion of grain refinement in the nickel-copper alloy melt, and will not over-react or volatilize due to long-term high temperature.

[0046] S5: Tilt the smelting furnace to allow the nickel-copper alloy melt containing tin to flow into the chute, and start casting when the temperature of the nickel-copper alloy melt in the chute is higher than the melting point of the nickel-copper alloy + 100° C.;

[0047] In this step, it should be ensured that the launder is ready, and the launder should be provided with a liquid level control system to ensure that the composition of the melt in the launder is uniform. In addition, the launder should be sealed with a cover plate and filled with an inert gas (such as argon) for protection to prevent the nickel-copper alloy melt from contacting with air and oxidizing. Further, a guide tube needs to be connected below the launder to ensure that the center of the guide tube, the center of the crystallizer and the center of the pull head are consistent to ensure that the nickel-copper alloy melt flows smoothly in the launder.

[0048] It should be noted that controlling the flow channel temperature to be higher than the melting point of the nickel-copper alloy by +100°C can ensure that the nickel-copper alloy melt has good fluidity, while avoiding melt decomposition caused by too high a temperature or melt solidification caused by too low a temperature.

[0049] S6: Perform downward casting through a crystallizer, and use an electric vibrator or an electromagnetic vibrator as a vibration source to generate periodic vibration for casting, the vibration frequency is 50 times / minute, the downward casting speed is 50-60mm / minute, and the crystallizer is cooled by cooling water, and the cooling water temperature is maintained at room temperature to obtain a nickel-copper alloy.

[0050] In this step, during the vibration process, the nickel-copper alloy melt is subjected to periodic mechanical disturbances, which can interrupt the growing crystals and promote the final nucleus formation, thereby refining the grains, and refining the grains can improve the strength, plasticity and toughness of the nickel-copper alloy, and improve the comprehensive mechanical properties of the nickel-copper alloy. In addition, vibration can also improve the fluidity of the nickel-copper alloy melt, so that the gas and inclusions therein are better discharged, and the discharge of pores and inclusions can improve the density and purity of the nickel-copper alloy, thereby improving the mechanical properties and corrosion resistance of the nickel-copper alloy.

[0051] S7: Saw the riser and the bottom sheet of the nickel-copper alloy, and test the element composition at the same time. Polish the surface of the nickel-copper alloy that passes the test with a polishing device to remove surface defects such as oxide scale;

[0052] S8: After welding, the qualified nickel-copper alloy and the electroslag dummy electrode are placed in an electroslag furnace, and a pre-sintered and dried electroslag slag agent (for example, CaF2 20%-40%, with the remainder being 431 solder, sintered and dried at a temperature of 800 to 1000°C for 1-2h) is placed under the nickel-copper alloy. The power is turned on to form a current loop between the electroslag dummy electrode and the nickel-copper alloy so that the nickel-copper alloy is re-melted. The re-melted nickel-copper alloy is taken out of the electroslag furnace for cooling to form the final nickel-copper alloy.

[0053] In this step, the electroslag slag agent can absorb and remove harmful impurities in the nickel-copper alloy, such as oxides, sulfides, etc., so as to improve the purity of the nickel-copper alloy, and then improve the mechanical properties and corrosion resistance of the nickel-copper alloy. In addition, during the electroslag remelting process, the slag can promote the uniform distribution of each component in the nickel-copper alloy, reduce segregation (segregation refers to the uneven concentration of certain elements in the nickel-copper alloy in different regions, which will affect the performance of the nickel-copper alloy), make the microstructure of the nickel-copper alloy more uniform, thereby improving the mechanical properties and corrosion resistance of the nickel-copper alloy.

[0054] In summary, the nickel-copper alloy ingot is remelted through electroslag remelting. This process can not only remove harmful impurities in the nickel-copper alloy and improve the purity of the nickel-copper alloy, but also promote the uniform distribution of components in the nickel-copper alloy and improve the microstructure, thereby significantly improving the mechanical properties and corrosion resistance of the nickel-copper alloy and ensuring the quality and performance of the final product.

[0055] S9: The nickel-copper alloy after electroslag remelting is subjected to surface treatment and quality inspection again to ensure that the composition and structure of the nickel-copper alloy after electroslag remelting meet the standards.

[0056] In this step, the test items include component analysis and impurity content determination to ensure the consistency and stability of the material. If the test fails, appropriate measures need to be taken to correct or scrap it.

[0057] In another exemplary embodiment, the present application also provides another method for preparing a nickel-copper alloy, the preparation method comprising the following steps:

[0058] S10: electrolytic copper plate, nickel plate and aluminum alloy are prepared in the proportion of 50-70%, 20-40% and 1-10%;

[0059] In this step, the aluminum element is also added in the form of an alloy, for example, an aluminum-aluminum alloy or an aluminum-iron alloy.

[0060] In this step, aluminum can form a strengthening phase in the alloy, and compared with tin alloy, these strengthening phases can further improve the grain boundary strength and intragranular strength of nickel-copper alloy, thereby further improving the overall strength and hardness of nickel-copper alloy. Although tin can also improve the grain boundary strength of nickel-copper alloy, the strengthening effect is relatively weaker than aluminum, and the improvement effect on the overall strength and hardness of nickel-copper alloy is limited. In addition, aluminum can form a stable oxide film (SiO2) at high temperature, which can effectively prevent oxygen from further penetrating into the inside of nickel-copper alloy. Although tin can also form a protective film at high temperature, it has been verified that its stability is not as good as the protective film formed by aluminum.

[0061] S20: firstly adding the aluminum alloy into the smelting furnace for smelting, and when the temperature of the smelting furnace rises to the temperature at which the aluminum alloy is completely melted (about 700-800° C.), the temperature is continued to rise, and when the furnace temperature reaches the temperature at which the electrolytic copper plate and the nickel plate begin to melt (usually above 1000° C.), the electrolytic copper plate and the nickel plate are added for smelting to obtain a nickel-copper alloy melt containing aluminum elements;

[0062] S30: adding aluminum powder and magnesium fluoride to the nickel-copper alloy melt containing aluminum element in sequence, and controlling the temperature in the smelting furnace to be 200° C. higher than the melting point of the nickel-copper alloy;

[0063] In this step, compared with charcoal, aluminum powder reacts with oxygen in the nickel-copper alloy melt at high temperature to generate aluminum oxide (Al2O3), thereby removing oxides in the nickel-copper alloy melt. Compared with charcoal, aluminum powder has a stronger reducing ability and can more thoroughly remove oxides in the nickel-copper alloy melt, thereby improving the purity of the nickel-copper alloy.

[0064] Using magnesium fluoride instead of calcium fluoride as a slag-forming agent can help form a slag with better fluidity, which can absorb and encapsulate non-metallic inclusions and gases in the nickel-copper alloy melt. Compared with calcium fluoride, magnesium fluoride has a lower melting point and better fluidity, and can more effectively remove impurities and gases in the nickel-copper alloy melt, thereby further improving the purity and density of the nickel-copper alloy.

[0065] In addition, as for the temperature setting, the reasons are as mentioned above and will not be repeated here.

[0066] S40: maintaining the temperature in the smelting furnace higher than the melting point of the nickel-copper alloy by 200°C, and introducing argon gas to help gases (especially hydrogen and oxygen) escape from the smelting furnace to reduce the formation of pores and bubbles, and adding a small amount of cerium (Ce) 5 minutes before leaving the furnace (the amount of cerium (Ce) added is between 0.01% and 0.05% of the total weight of the nickel-copper alloy, but the specific amount needs to be determined according to the actual alloy formula and the required performance indicators);

[0067] In this step, compared with lanthanum (La), cerium (Ce) has a stronger grain refining effect, which can further improve the mechanical properties of nickel-copper alloys. In addition, cerium (Ce) can form a more stable and dense oxide film at high temperatures, which can more effectively prevent oxygen from further penetrating into the interior of the nickel-copper alloy and improve the oxidation resistance of the alloy. In contrast, although lanthanum (La) can also form a protective film, its stability is slightly inferior to that of the film formed by cerium (Ce). More importantly, cerium (Ce) is more chemically active than lanthanum (La), which means that cerium (Ce) is more likely to react with other elements during the smelting process to form beneficial compounds or phases, thereby better improving the corrosion resistance and wear resistance of nickel-copper alloys.

[0068] S50: Tilt the smelting furnace to allow the nickel-copper alloy melt containing aluminum elements to flow into the chute, and start casting when the temperature of the nickel-copper alloy melt in the chute is higher than the melting point of the nickel-copper alloy + 100° C.;

[0069] S60: Downward casting is performed through a crystallizer, and an electric vibrator or an electromagnetic vibrator is used as a vibration source to generate periodic vibration for casting, the vibration frequency is 50 times / minute, the downward casting speed is 50-60mm / minute, and the crystallizer is cooled by cooling water, and the cooling water temperature is maintained at room temperature to obtain a nickel-copper alloy.

[0070] S70: Saw the riser and bottom sheet of nickel-copper alloy, and test the element composition at the same time. Polish the surface of the nickel-copper alloy that passes the test with polishing equipment to remove surface defects such as oxide scale;

[0071] S80: After welding the qualified nickel-copper alloy and the electroslag dummy electrode, put them into an electroslag furnace, and place a pre-sintered and dried electroslag slag agent (for example, CaF2: 20%-40%, Al2O3: 10%-20%, and the balance is 431 solder, sintered and dried at a temperature of 800 to 1000°C for 1-2h) under the nickel-copper alloy, turn on the power, and form a current loop between the electroslag dummy electrode and the nickel-copper alloy to re-melt the nickel-copper alloy, and take the re-melted nickel-copper alloy out of the electroslag furnace for cooling to form the final nickel-copper alloy.

[0072] In this step, CaF2 can continue to maintain its advantages of lowering the melting point of slag and improving fluidity, which helps to better absorb and encapsulate non-metallic inclusions and gases in the nickel-copper alloy. Adding an appropriate amount of Al2O3 can further improve the fluidity of the slag, allowing it to maintain good fluidity at a lower temperature, which helps to more effectively remove impurities. In addition, Al2O3 has a strong adsorption capacity and can more effectively absorb and encapsulate harmful impurities such as oxides and sulfides in the nickel-copper alloy, thereby further improving the purity of the nickel-copper alloy.

[0073] S90: The nickel-copper alloy after electroslag remelting is subjected to surface treatment and quality inspection again to ensure that the composition and structure of the nickel-copper alloy after electroslag remelting meet the standards.

[0074] In this step, the test items include component analysis and impurity content determination to ensure the consistency and stability of the material. If the test fails, appropriate measures need to be taken to correct or scrap it.

[0075] In another exemplary embodiment, the present application also provides another method for preparing a nickel-copper alloy, the preparation method comprising the following steps:

[0076] S100: Electrolytic copper plate, nickel plate and manganese alloy are prepared in the proportion of 50-70%, 20-40% and 1-10%;

[0077] In this step, the manganese alloy includes, for example, manganese-iron alloy and manganese-copper alloy. Compared with aluminum alloy, manganese can form a stronger strengthening phase in the nickel-copper alloy, and these strengthening phases can further significantly improve the grain boundary strength and intracrystalline strength of the nickel-copper alloy. Specifically, manganese can form a solid solution in the nickel-copper matrix, thereby increasing the lattice distortion to improve the strength of the nickel-copper alloy; manganese can also form finer precipitated phases, and these finer precipitated phases are distributed at the grain boundaries and within the crystal, hindering the movement of dislocations, and further improving the strength and hardness of the nickel-copper alloy.

[0078] S200: firstly add the manganese alloy into the smelting furnace for smelting, and when the temperature of the smelting furnace rises to the temperature at which the manganese alloy is completely melted (about 1246° C.), continue to heat up, and when the furnace temperature reaches the temperature at which the electrolytic copper plate and the nickel plate begin to melt (usually above 1000° C.), add the electrolytic copper plate and the nickel plate for smelting to obtain a nickel-copper alloy melt containing manganese elements;

[0079] S300: adding titanium powder and lithium fluoride to the nickel-copper alloy melt containing manganese element in sequence, and controlling the temperature in the smelting furnace to be 200° C. higher than the melting point of the nickel-copper alloy;

[0080] In this step, the reducing ability of titanium powder far exceeds that of aluminum powder. It has extremely strong reducing ability at high temperature, which can more thoroughly remove oxides in nickel-copper alloy and improve the purity of nickel-copper alloy. Lithium fluoride has a lower melting point and better fluidity. Using lithium fluoride (LiF) as a slag-forming agent can more effectively form slag and remove non-metallic inclusions and gases in the nickel-copper alloy melt. By using titanium powder and lithium fluoride in combination, titanium powder provides strong reducing ability and lithium fluoride provides high-quality slag-forming performance. The combination of the two can achieve the best purification effect.

[0081] Similarly, regarding the temperature setting, the reasons are as mentioned above and will not be repeated here.

[0082] S400: maintaining the temperature in the smelting furnace higher than the melting point of the nickel-copper alloy by 200° C., and introducing argon gas to help gases (especially hydrogen and oxygen) escape from the smelting furnace to reduce the formation of pores and bubbles, and adding a small amount of neodymium (Nd) accounting for 0.01% to 0.1% of the total weight of the nickel-copper alloy 5 minutes before the nickel-copper alloy melt is taken out of the furnace. For example, if the total weight of the nickel-copper alloy is 1000 kg, the amount of lanthanum added is between 100 grams and 1000 grams);

[0083] In this step, compared with cerium (Ce), neodymium (Nd) has a stronger grain refinement ability, which can further improve the strength, plasticity and toughness of the nickel-copper alloy. Compared with cerium (Ce), neodymium (Nd) can form a more stable and dense oxide film at high temperature, which can more effectively prevent oxygen from further penetrating into the nickel-copper alloy. In addition, neodymium (Nd) has a strong purification effect and can more effectively remove gases and non-metallic inclusions in the alloy melt. Neodymium (Nd) can react with oxygen, sulfur and other elements in the melt to generate stable compounds. These compounds float on the surface of the melt in the form of slag, thereby being removed, improving the purity of the nickel-copper alloy.

[0084] S500: Tilt the smelting furnace to allow the nickel-copper alloy melt containing manganese elements to flow into the chute, and start casting when the temperature of the nickel-copper alloy melt in the chute is higher than the melting point of the nickel-copper alloy + 100°C;

[0085] S600: Downward casting is performed through a crystallizer, and an electric vibrator or an electromagnetic vibrator is used as a vibration source to generate periodic vibration for casting. The vibration frequency is 50 times / minute, the downward casting speed is 50-60mm / minute, and cooling water is used to cool the crystallizer. The cooling water temperature is maintained at room temperature to obtain a nickel-copper alloy.

[0086] S700: Saw the riser and bottom sheet of nickel-copper alloy ingots, and test the element composition at the same time. Polish the surface of the nickel-copper alloy ingots that pass the test with polishing equipment to remove surface defects such as oxide scale;

[0087] S800: After welding the qualified nickel-copper alloy and the electroslag dummy electrode, put them into an electroslag furnace, and place a pre-sintered and dried electroslag slag agent (for example, CaF2: 20%-40%, Al2O3: 10%-20%, CaO: 5%-10%, and the balance is 431 solder) under the nickel-copper alloy. Turn on the power supply to form a current loop between the electroslag dummy electrode and the nickel-copper alloy, so that the nickel-copper alloy is re-melted. The re-melted nickel-copper alloy is taken out of the electroslag furnace for cooling to form the final nickel-copper alloy.

[0088] In this step, compared with using only CaF2 and Al2O3, using CaF2, Al2O3 and CaO as electroslag slag agents can further improve the fluidity, adsorption capacity and thermal stability of the slag, wherein the addition of CaO can effectively reduce the melting point of the slag, improve the fluidity of the slag, make it easier to flow during the smelting process, and better adsorb and wrap harmful impurities in the alloy, such as oxides and sulfides. At the same time, CaO has good thermal stability at high temperatures, which can further improve the purification effect of the slag, ensure the stability and effectiveness of the electroslag remelting process, thereby more effectively removing impurities in the nickel-copper alloy and improving the purity and comprehensive performance of the nickel-copper alloy.

[0089] S900: The nickel-copper alloy after electroslag remelting is subjected to surface treatment and quality inspection again to ensure that the composition and structure of the nickel-copper alloy after electroslag remelting meet the standards.

[0090] In this step, the test items include component analysis and impurity content determination to ensure the consistency and stability of the material. If the test fails, appropriate measures need to be taken to correct or scrap it.

[0091] In another exemplary embodiment, the present application also provides a turbine blade for an engine, wherein the turbine blade is made of the nickel-copper alloy as described above.

[0092] In this embodiment, it is found that the turbine blades prepared using the nickel-copper alloy prepared by the present method have the following advantages over the nickel-copper alloy prepared by the existing method:

[0093] First, it can improve thermal efficiency: since the nickel-copper alloy prepared by this method can work stably at higher temperatures, the turbine blades can operate in a more efficient temperature range.

[0094] Second, it can extend the service life: the nickel-copper alloy prepared by this method has excellent corrosion resistance and oxidation resistance, which can reduce the maintenance requirements of turbine blades and extend the service life of the blades.

[0095] Next, the present application compares the performance of the nickel-copper alloy prepared by the present method with that of the nickel-copper alloy prepared by the prior art. The specific comparison results are shown in Table 1:

[0096] Table 1

[0097]

[0098]

[0099] In Table 1, through the above comparison, it can be seen that the nickel-copper alloy prepared by the present method is significantly superior to the nickel-copper alloy prepared by the existing method in multiple performance indicators, especially in terms of strength, ductility, impact toughness, purity and corrosion resistance. These advantages make the nickel-copper alloy prepared by the present method more suitable for application in high-demand industrial fields.

[0100] In addition, the present application also compares the properties of nickel-copper alloys prepared without using the electroslag remelting process and with using the electroslag remelting process, as shown in Table 2:

[0101] Table 2

[0102]

[0103]

[0104] It can be seen from Table 2 that the nickel-copper alloy prepared by the electroslag remelting process is significantly better than the nickel-copper alloy prepared without the electroslag remelting process in various performance indicators. These advantages make the nickel-copper alloy prepared by the electroslag remelting process more suitable for application in high-demand industrial fields.

[0105] Figure 2 The nickel-copper alloy (CuNi) doped with manganese element is prepared based on the method of the present application. 44 Mn1 alloy as an example) metallographic diagram, Figure 2 In the present invention, the nickel-copper alloy containing manganese prepared by the present method has uniform grain distribution, visible grain boundary cleaning, and no obvious phenomenon of different grain sizes, which indicates that the addition of manganese effectively promotes uniform grain refinement and improves the uniformity of the microstructure of the alloy. In addition, Figure 2 No pores, cracks or looseness were observed in the CuNi 44 Mn1 alloy has a higher density, which reduces the potential stress concentration points; secondly, it can show that CuNi 44 Mn1 alloy has good integrity and reliability; thirdly, it can show that CuNi 44 The microstructure of Mn1 alloy is compact without obvious pores or voids.

[0106] In summary, Figure 2 It can be seen that the CuNi prepared by the method described in this application 44 Mn1 alloy has the characteristics of high density, good integrity and compact structure, and thus has good mechanical properties.

[0107] Figure 3 The nickel-copper alloy (CuNi) doped with aluminum element prepared by the method of the present application 30 Al2 alloy as an example) metallographic diagram, Figure 3 The grain distribution of the nickel-copper alloy containing aluminum prepared by this method is also relatively uniform, the grain boundary cleaning is visible, and there is no obvious phenomenon of different grain sizes, which shows that the addition of aluminum effectively promotes the uniform refinement of grains and improves the uniformity of the microstructure of the alloy. In addition, Figure 3 No obvious pores, cracks or looseness were observed in the CuNi 30 Al2 alloy also has a higher density, reducing potential stress concentration points; secondly, it can show that CuNi 30 Al2 alloy has good integrity and reliability; thirdly, it can show that CuNi 30 The microstructure of Al2 alloy is compact without obvious pores or voids.

[0108] In summary, CuNi 44 Mn1 alloy and CuNi 30 The Al2 alloys all showed good grain uniformity and microstructural compactness, which indicated that the addition of manganese and aluminum elements had a positive effect on the microstructure of this nickel-copper alloy.

[0109] The above are only preferred embodiments of the present application, and are not intended to limit the patent scope of the present application. Any equivalent structure or equivalent process transformation made using the contents of the present application specification and drawings, or directly or indirectly applied in other related technical fields, are also included in the patent protection scope of the present application.

Claims

1. A method for preparing a nickel-copper alloy, characterized in that: The method comprises: Electrolytic copper plate, nickel plate and strengthening phase are provided in a certain proportion; Firstly, the strengthening phase is put into a smelting furnace for smelting, and then the electrolytic copper plate and the nickel plate are put into a smelting furnace for smelting to obtain a nickel-copper alloy melt; Adding a reducing agent and a slag-forming agent into the nickel-copper alloy melt to purify the nickel-copper alloy melt; Passing an inert gas and adding a rare earth element into the purified nickel-copper alloy melt; Casting the nickel-copper alloy melt after adding the rare earth element to obtain the nickel-copper alloy; The nickel-copper alloy is electroslag remelted and cooled to obtain a final nickel-copper alloy.

2. The method for preparing a nickel-copper alloy according to claim 1, characterized in that: The strengthening phase includes any one of the following: tin alloy, aluminum alloy and manganese alloy.

3. The method for preparing a nickel-copper alloy according to claim 1, characterized in that: The electrolytic copper plate, nickel plate and strengthening phase need to be cleaned and preheated before smelting.

4. The method for preparing a nickel-copper alloy according to claim 1, characterized in that: During the smelting process, the temperature of the smelting furnace needs to be controlled to be 200° C. higher than the melting point of the nickel-copper alloy.

5. The method for preparing a nickel-copper alloy according to claim 1, characterized in that: The reducing agent includes any one of the following: charcoal, aluminum powder and titanium powder.

6. The method for preparing a nickel-copper alloy according to claim 1, characterized in that: The slag-forming agent includes any one of the following: calcium fluoride, magnesium fluoride and lithium fluoride.

7. The method for preparing a nickel-copper alloy according to claim 1, characterized in that: The rare earth element includes any one of the following: lanthanum, cerium and neodymium.

8. The method for preparing a nickel-copper alloy according to claim 1, characterized in that: The nickel-copper alloy melt after adding the rare earth element is vibrated and cast.

9. A nickel-copper alloy, characterized in that: The components of the nickel-copper alloy and the content of each component include: Copper: 50-70% Nickel: 20-40% Strengthening phase: 1-10%.

10. A turbine blade for an engine, characterized in that: The turbine blade is made based on the nickel-copper alloy according to claim 9.

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