Titanium-aluminum alloy and method for manufacturing the same

Abstract

The method belongs to the field of titanium alloy, and particularly relates to a titanium-aluminum alloy and a preparation method thereof. The method comprises the following steps: uniformly mixing titanium oxide, a reducing agent and in-situ slagging agent (aluminum-calcium alloy particles), a slagging agent and potassium chlorate in a mass ratio of 1:(0.92-1.69):(0-0.78):(0.2-0.68) to obtain a mixture; initiating an in-situ composite thermal reduction reaction by taking a part of the mixture to obtain a high-temperature molten pool, the upper layer of the molten pool being a reduction slag and the lower layer being a titanium-aluminum alloy melt; then continuously and uniformly adding the remaining material into the high-temperature molten pool after being pressed into balls to react, so that the temperature of the high-temperature molten pool is maintained at 1400-1600 DEG C; and separating the slag and the gold while the composite thermal reduction reaction is being carried out, until the reaction is completed, without refining, to directly obtain the titanium-aluminum alloy. The method does not need secondary refining, and the titanium-aluminum alloy ingot can be obtained after cooling and slag removal, so that the production process can be effectively shortened, the synthesis cost can be reduced, and the product quality is relatively high.

Description

Technical Field

[0001] This invention belongs to the field of titanium alloys, and specifically relates to a titanium-aluminum alloy and its preparation method. Background Technology

[0002] Titanium alloys are characterized by high strength, low density, good high-temperature performance, good corrosion resistance, and good biocompatibility. They are one of the best lightweight high-temperature structural materials in terms of comprehensive performance and are widely used in aerospace, marine engineering, automotive industry, biomedicine and other fields.

[0003] Currently, the main methods for preparing titanium-aluminum alloys include powder metallurgy, electrodeposition, and aluminothermic reduction. (1) Powder metallurgy Powder metallurgy is a process that uses titanium and aluminum powders to form titanium-aluminum alloys through a series of forming and sintering processes, such as mixing, pressing, and vacuum high-temperature sintering. It has advantages such as near-net-shape forming, high processing efficiency, low cost, and no segregation.

[0004] Chinese invention patent CN 106191493 B, with an authorization announcement date of January 12, 2018, discloses a method for preparing powder metallurgy titanium alloys. This method uses TiH2 powder, Ti powder, and other alloying elements as raw materials, mixes them uniformly, presses them into shape, heats them under high vacuum to decompose TiH2, sintersulates them in a hydrogen atmosphere, removes hydrogen under vacuum, and cools to obtain the powder metallurgy titanium alloy. This method can purify the powder surface, improve alloy purity, and promote densification; however, the process cycle is relatively long, and incomplete dehydrogenation can easily affect the material properties.

[0005] The preparation of titanium-aluminum alloys by powder metallurgy has the disadvantages of complex processes and high costs.

[0006] (2) Electrodeposition method Chinese invention patent CN 113913882 B, with an authorization announcement date of April 11, 2023, discloses a method for preparing titanium-aluminum alloys by low-temperature electrodeposition using titanium oxide as a raw material. The method first dissolves anhydrous AlCl3 in ethylene carbonate, then adds TiCl4 and stirs evenly to prepare a carbon solvated ionic liquid. The solvated ionic liquid is then used as an electrolyte to form an electrolytic cell system, and electrodeposition is performed using a three-electrode system. The anode is titanium oxide. After electrodeposition, the cathode is removed, cleaned to remove the electrolyte adhering to the surface, and dried to obtain an aluminum-titanium alloy on the cathode surface.

[0007] Electrodeposition has the advantage of low energy consumption, but related methods are still in the laboratory stage and suffer from high costs and immature technology.

[0008] (3) Aluminothermic reduction method The aluminothermic reduction method involves adding a slag-forming agent to titanium oxides, which are then aluminothermally reduced to obtain a high-temperature slag-metal mixture. The slag and metal are then separated to prepare titanium-aluminum alloy ingots. This method has advantages such as high production efficiency and low energy consumption, and can effectively reduce the production cost of titanium alloys. Therefore, the aluminothermic reduction method is one of the most promising industrial production methods.

[0009] Chinese invention patent CN 104120304 B, with an authorization announcement date of April 6, 2016, discloses a method for preparing titanium-aluminum alloy based on aluminothermic self-propagating spray deep reduction. The method involves obtaining a high-temperature melt through an aluminothermic reduction reaction, separating the melt by heat preservation smelting, refining the slag layer by secondary slag washing, and then refining the high-temperature alloy melt through deep reduction. Finally, the high-temperature melt is cooled to room temperature to remove the upper smelting slag to obtain the titanium-aluminum alloy.

[0010] Chinese invention patent CN 105154716 B, with an authorization announcement date of March 8, 2017, discloses a method and apparatus for preparing titanium-aluminum alloy. The method improves the gold slag separation effect by carrying out an aluminothermic reduction reaction in a hypergravity system environment, thereby preparing a high-performance titanium-aluminum alloy.

[0011] Chinese invention patent CN 107151752 B, with an authorization announcement date of October 23, 2018, discloses a method for preparing titanium alloys based on aluminothermic self-propagating gradient reduction and slag washing refining. The method uses a gradient feeding method to carry out aluminothermic self-propagating reaction to obtain a high-temperature melt, which is then subjected to gradient reduction smelting. After the feeding is completed, the melt is held at a certain temperature for further melting and separation. Then, the high-temperature melt is subjected to slag washing refining, and finally, the slag is removed to obtain the titanium alloy.

[0012] In the aluminothermic reduction process for preparing titanium-aluminum alloys, incomplete aluminothermic reduction results in a large amount of low-valence titanium oxides in the slag, increasing the slag melting point and viscosity. Simultaneously, the rapid heating and cooling during the aluminothermic reduction reaction leads to a short slag-metal separation time, making it difficult for the added slag-forming agent to completely combine with the generated alumina inclusions to form a low-melting-point slag phase, thus resulting in residual alumina inclusions in the titanium-aluminum alloy. These two factors lead to technical challenges in the aluminothermic preparation of titanium-aluminum alloys, including high inclusion content and low titanium recovery. Existing technologies often require deep reduction of the slag-metal mixture obtained from aluminothermic reduction to improve titanium recovery, reduce titanium oxides in the slag to improve its physicochemical properties, and further increase titanium yield. Secondary smelting, separation, and refining are also necessary to effectively remove inclusions and improve alloy purity. This complicates the titanium-aluminum alloy preparation process, reduces production efficiency, and increases energy consumption. Summary of the Invention

[0013] The first objective of this invention is to provide a method for preparing titanium-aluminum alloys, which solves the problems of complex process flow and low production efficiency in the existing aluminothermic reduction method for preparing titanium-aluminum alloys.

[0014] The second objective of this invention is to provide a titanium-aluminum alloy prepared by the above method, so as to solve the problem that inclusions are difficult to remove quickly and effectively in the preparation of titanium-aluminum alloys based on the aluminothermic reduction method.

[0015] To achieve the above objectives, the technical solution of the titanium-aluminum alloy preparation method of the present invention is as follows: A method for preparing a titanium-aluminum alloy includes the following steps: (1) Titanium oxide, reducing agent and in-situ slag-forming agent aluminum-calcium alloy particles, slag-forming agent and potassium chlorate in a mass ratio of 1:(0.92~1.69):(0~0.78):(0.2~0.68) are mixed evenly to obtain a mixture. (2) Take a portion of the mixed materials to initiate an in-situ composite thermal reduction reaction to obtain a high-temperature molten pool. The upper layer of the molten pool is a reducing slag and the lower layer is a titanium-aluminum alloy melt. Then, the remaining materials are pressed into balls and continuously and uniformly added to the high-temperature molten pool for reaction, so that the temperature of the high-temperature molten pool is maintained at 1400~1600℃. While reacting, the composite thermal reduction is carried out to obtain a slag-gold mixed melt for slag-gold separation until the reaction is completed. Without refining, titanium-aluminum alloy is directly obtained.

[0016] This invention is an improved version that utilizes aluminum-calcium alloy particles as a reducing agent and in-situ slag-forming agent. Through aluminum-calcium composite thermal reduction and in-situ slag formation, it directly achieves heat preservation and enhanced gold-slag separation, realizing the complete reduction of low-valent titanium oxides. This reduces oxide inclusions in the alloy and lowers the melting point of the slag, facilitating gold-slag separation. This method eliminates the need for secondary refining; titanium-aluminum alloy ingots can be obtained directly after cooling and slag removal. It effectively shortens the production process, reduces synthesis costs, and produces high-quality products.

[0017] Preferably, in step (2), a portion of the mixture accounts for 10-20% of the total mass of the mixture, and the remaining material is pressed into pellets with a diameter of 1-3 cm under a pressure of 5-20 MPa. Compared with loose powder, the advantages of pressing into pellets are: stable combustion, continuous heat conduction, and easy stable control of the reaction process and molten pool temperature; at the same time, the slag phase is fully melted, the viscosity is low, the slag-forming reaction is complete, the melt fluidity is good, which is conducive to the rapid and complete separation of slag and gold.

[0018] More preferably, in step (2), the high-temperature molten pool is maintained at 1400~1600℃ for 5~8 minutes. The temperature of the high-temperature molten pool can be controlled by the feeding rate. Maintaining the temperature within the above range allows small inclusions sufficient time to float, resulting in good slag-gold separation and high alloy purity. If the maintenance time is too short, inclusions will not have enough time to float, leading to gas retention and porosity, resulting in high alloy porosity and numerous inclusions. During gold-slag separation, no control is required to achieve natural gold-slag separation.

[0019] Preferably, the mass content of Ca in the aluminum-calcium alloy particles is 10-56%; the slag-forming agent in step (1) is CaO; the mass ratio of titanium oxide, aluminum-calcium alloy particles, CaO and potassium chlorate is 1:(0.92-1.69):(0-0.55):(0.2-0.54). Controlling the Ca content in the aluminum-calcium alloy to the above range and using the above preferred ratio has the following advantages: CaO completely combines with the generated alumina inclusions to form low-melting-point calcium aluminate, completely eliminating alumina inclusions in the alloy; utilizing the strong reducing properties of calcium to completely reduce titanium oxide, lowering the slag melting point while increasing titanium yield; and optimizing the slag physicochemical properties by adding a certain amount of slag-forming agent, strengthening slag-metal separation, and minimizing the calcium content in the aluminum-calcium alloy to reduce production costs.

[0020] More preferably, the titanium oxide is titanium dioxide, rutile, high-titanium slag, or a mixture thereof; the particle size is 0.1 mm ≤ titanium oxide ≤ 2 mm; the particle size is 0.5 mm ≤ aluminum-calcium alloy ≤ 3 mm; the particle size is 0.01 mm ≤ slag-forming agent ≤ 2 mm; and the particle size is 0.1 mm ≤ potassium chlorate ≤ 2 mm. Titanium oxides such as titanium dioxide, rutile, and high-titanium slag are low-cost and readily available raw materials; at the same time, using raw materials with the above-mentioned particle sizes is beneficial for efficient and uniform mixing of the components.

[0021] Preferably, the raw materials, except for potassium chlorate, are ball-milled, mixed, and preheated. After preheating, they are mixed evenly with potassium chlorate to obtain the mixture. This method prepares the material for a subsequent rapid in-situ composite thermal reduction reaction.

[0022] More preferably, the preheating temperature is 50~80℃ and the time is 30~60 min. Under this preheating condition, the temperature of the raw materials can reach internal and external equilibrium, improving the stability and consistency of the reaction.

[0023] Preferably, during ball milling, the rotation speed is 200-320 r / min, the material-to-ball ratio is (3-6):1, and the milling time is 3-6 h. This ball milling method can quickly achieve homogenization of the components and improve the consistency of the thermal reduction reaction.

[0024] A titanium-aluminum alloy prepared using the above method.

[0025] The titanium-aluminum alloy provided by this invention has lower production costs, lower inclusion content, and higher product quality compared to titanium-aluminum alloys prepared by existing aluminothermic self-propagating methods. Taking the produced TiAl35 alloy as an example, its Vickers hardness reaches 445HV, yield strength reaches 466MPa, fracture strength reaches 547MPa, and Young's modulus reaches 154 GPa.

[0026] Preferably, the titanium-aluminum alloy contains 20-55% Al, 0.01-0.08% Ca, and 0.005-0.03% O. Maintaining the Ca and O content at low levels will not affect the various properties of the titanium-aluminum alloy.

[0027] Compared with the prior art, the present invention achieves the following beneficial effects: 1. In the traditional aluminothermic reduction method for preparing titanium alloys, an excess of aluminum is generally added to ensure sufficient reduction. Otherwise, insufficient reduction will result in the formation of low-valence titanium oxides, which not only increases slag viscosity and reduces slag-metal separation efficiency but also significantly reduces the titanium yield. However, adding excess aluminum causes the reduced titanium to combine with aluminum to form various intermediate compound phases, making it difficult to precisely control the alloy composition. By using an aluminum-calcium based alloy as a reducing agent and adjusting the Al content in the alloy particles, the Al content in the prepared titanium-aluminum alloy can be controlled, solving the problem of difficult composition control in the aluminothermic reduction method for preparing titanium-aluminum alloys.

[0028] 2. By using in-situ slag formation in the aluminum-calcium composite thermal reduction process, the technical problem of not being able to completely remove alumina inclusions by simply adding an external slag-forming agent in the traditional aluminothermic method is overcome. Furthermore, by designing and controlling the composition of aluminum-calcium alloy particles and optimizing the ratio of in-situ slag and slag-forming agent, the composition and physicochemical properties of the reduction slag are controlled, and the heat preservation effect is directly enhanced to improve the gold slag separation effect. The operation process is simple, the product contains fewer inclusions, and the performance is excellent.

[0029] 3. This method achieves complete reduction of low-valent titanium oxides by designing the calcium content in aluminum-calcium alloy particles, reducing low-valent titanium oxide inclusions in the alloy and improving product quality; at the same time, it reduces low-valent titanium oxide inclusions in the alloy and slag, lowers the melting point and viscosity of the slag, and facilitates gold-slag separation. Attached Figure Description

[0030] Figure 1 Metallographic image of the titanium-aluminum alloy prepared in Example 2 of this invention; Figure 2 Metallographic image of the titanium-aluminum alloy prepared in Example 3 of this invention; Figure 3 Metallographic image of the titanium-aluminum alloy prepared for Comparative Example 1. Detailed Implementation

[0031] (a) Preferred embodiments of the titanium-aluminum alloy and its preparation method of the present invention.

[0032] This invention aims to provide a method for preparing titanium alloys that features a short process flow, high production efficiency, low energy consumption, and high product quality. Unlike existing aluminothermic reduction methods that use aluminum as the main reducing agent, this method uses aluminum-calcium alloy particles as both a reducing agent and an in-situ slag-forming agent. By designing the calcium content in the aluminum-calcium alloy particles, the composition of inclusions can be controlled, reducing inclusions. Combined with optimized slag-forming agent ratios, the composition of the reduction slag can be controlled, improving slag formation and gold-slag separation. Furthermore, by controlling the temperature and holding time of the high-temperature molten pool during the thermal reduction process, no secondary refining is required after the thermal reduction reaction, resulting in a highly efficient low-inclusion titanium-aluminum alloy.

[0033] This method is for the in-situ composite thermal reduction of metals to prepare titanium-aluminum alloys. The raw materials are titanium oxide, aluminum-calcium alloy particles, slag-forming agent and potassium chlorate. The mass ratio of titanium oxide, aluminum-calcium alloy particles, slag-forming agent and potassium chlorate can be 1:(0.92~1.69):(0~0.78):(0.2~0.68). Among them, the amount of aluminum-calcium alloy particles is sufficient to completely reduce the titanium oxide, serving as the sole reducing agent. The amount of slag-forming agent is sufficient to combine with the slag formed in-situ by the aluminum-calcium composite thermal reduction to form a slag phase with low melting point, low density and low viscosity, which is conducive to rapid separation of slag and metal.

[0034] Regarding raw materials, the particle size of titanium oxide is 0.1 mm ≤ 2 mm; the particle size of aluminum-calcium alloy is 0.5 mm ≤ 3 mm; the particle size of slagging agent is 0.01 mm ≤ 2 mm; and the particle size of potassium chlorate is 0.1 mm ≤ 2 mm. In the following examples, the particle size of titanium oxide is controlled to be 0.1 mm ≤ 2 mm; the particle size of aluminum-calcium alloy is 0.5 mm ≤ 3 mm; the particle size of slagging agent is 0.01 mm ≤ 0.5 mm; and the particle size of potassium chlorate is 0.1 mm ≤ 1 mm.

[0035] Specifically, the preparation method of the above-mentioned titanium-aluminum alloy adopts the following steps: (1) The dried titanium oxide and slag-forming agent are mixed in proportion and then mixed evenly with aluminum-calcium alloy particles.

[0036] Titanium oxide is a raw material for titanium dioxide, such as titanium dioxide, rutile, high-titanium slag, or mixtures thereof. The slag-forming agent is calcium oxide.

[0037] The aluminum-calcium alloy granules are composed of Al and Ca, with the mass fraction of Ca ranging from 10% to 56%, such as AlCa10, AlCa30, AlCa56, etc.

[0038] The drying temperature is 125~200℃, and the drying time is 10~16 h.

[0039] The uniform mixing here can be achieved by stirring or by ball milling. Ball milling is preferred. The optimal ball milling conditions are: rotation speed of 200~320 r / min, material-to-ball ratio of (3~6):1, and ball milling time of 3~6 h.

[0040] (2) The mixture obtained in step (1) is preheated, and an appropriate amount of potassium chlorate is added and mixed evenly. Then, a portion of the material (accounting for 10%-20% of the total material) is taken out and added to the graphite reactor to initiate a rapid in-situ composite thermal reduction reaction to obtain a high-temperature molten pool. The upper layer of the molten pool is a reducing slag and the lower layer is a titanium-aluminum alloy melt. Then, the remaining material (pressed into balls with a diameter of 1-3 cm under a pressure of 5-20 MPa) is continuously and evenly added to the molten pool to react and keep the temperature of the molten pool basically unchanged. While reacting, the composite thermal reduction is carried out to obtain a slag-gold mixture melt for slag-gold separation until the reaction ends. Finally, after cooling and slag removal, a titanium-aluminum alloy ingot is obtained.

[0041] In this step, the preheating temperature is 50~80℃, and the time is 30~60 minutes. All raw materials except potassium chlorate are preheated (to prevent spontaneous combustion or explosion during preheating) before being mixed thoroughly with potassium chlorate. Preheating provides a certain amount of heat to the reaction system, which is beneficial for a stable reaction.

[0042] Maintain the temperature of the high-temperature molten pool at 1400~1600℃ for 5~8 minutes.

[0043] The titanium-aluminum alloy obtained by the above method can be a TiAl35-65 alloy, which contains, in addition to Ti and Al, small amounts of impurity elements such as Ca, Fe, C, N, H, and O.

[0044] The typical mass composition of the above-mentioned titanium-aluminum alloy is as follows: Al 23.0~52.0%, Ca 0.01~0.08%, Fe 0.08~0.15%, C 0.006~0.010%, N 0.03~0.05%, H 0.008~0.01%, O 0.005~0.03%, with the balance being Ti. In the above-mentioned titanium-aluminum alloy, Fe, C, N, H, and O are impurities carried from the raw materials. The resulting titanium-aluminum alloy has significant advantages such as fewer inclusions and better mechanical properties.

[0045] The preferred embodiments described above will be illustrated below with specific examples.

[0046] Example 1 The method for preparing the titanium-aluminum alloy in this embodiment utilizes AlCa10 alloy particles to prepare TiAl35 (atomic ratio) alloy, and specifically adopts the following steps: (1) Place rutile, slag-forming agent calcium oxide and potassium chlorate in a drying oven for drying at 120°C for 10 hours.

[0047] (2) Rutile, aluminum-calcium alloy particles (Al: Ca=1:0.11) and slag-forming agent CaO were mixed in a mass ratio of 1:0.92:0.55. Then, mixing balls were added to the ball mill for ball milling and mixing. The material-to-ball ratio was 3:1, the rotation speed was 200 r / min, and the ball milling time was 3 h.

[0048] (3) Preheat the mixture to 50°C for 30 min.

[0049] (4) Add an appropriate amount of potassium chlorate (the mass ratio of titanium oxide to potassium chlorate is 1:0.54) to the mixture and mix evenly. Place the mixture in a ball mill mixer and mix for 30 min to obtain the mixture.

[0050] (5) Take out a portion of the material (accounting for 20% of the total material) and add it to the graphite reactor to initiate a rapid in-situ composite thermal reduction reaction to obtain a high-temperature molten pool (1400℃). The upper layer of the molten pool is a reducing slag and the lower layer is a titanium-aluminum alloy melt. Then, the remaining material, which has been pre-pressed into balls (pressure 5MPa, ball diameter 1cm), is continuously and uniformly added to the molten pool to react and keep the temperature of the molten pool basically unchanged (maintaining time 5 min). While reacting, the composite thermal reduction is carried out to obtain a slag-gold mixed melt for slag-gold separation until the reaction ends. Finally, after cooling and slag removal, a titanium-aluminum alloy ingot is obtained.

[0051] The titanium-aluminum alloy prepared in this embodiment is composed of the following components by mass fraction: Al 23.20%, Ca 0.08%, Fe 0.08%, C 0.009%, N 0.042%, H 0.008%, O 0.025%, and Ti as the balance.

[0052] Example 2 The method for preparing the titanium-aluminum alloy in this embodiment utilizes AlCa30 alloy particles to prepare TiAl45 (atomic ratio) alloy, specifically employing the following steps: (1) Place rutile, slag-forming agent calcium oxide and potassium chlorate in a drying oven for drying at 120°C for 12 hours.

[0053] (2) Rutile, aluminum-calcium alloy particles (Al: Ca=1:0.43), and slag-forming agent CaO were mixed in a mass ratio of 1:1.05:0.04. Then, mixing balls were added to the ball mill for ball milling and mixing. The material-to-ball ratio was 4:1, the rotation speed was 240 r / min, and the ball milling time was 4 h.

[0054] (3) Preheat the mixture to 60°C for 40 min.

[0055] (4) Add an appropriate amount of potassium chlorate to the mixture and mix evenly (the mass ratio of titanium oxide to potassium chlorate is 1:0.34). Place the mixture in a ball mill mixer and mix for 40 min to obtain the mixture.

[0056] (5) Take out a portion of the material (accounting for 15% of the total material) and add it to the graphite reactor to initiate a rapid in-situ composite thermal reduction reaction to obtain a high-temperature molten pool (1450℃). The upper layer of the molten pool is a reducing slag and the lower layer is a titanium-aluminum alloy melt. Then, the remaining material, which has been pre-pressed into balls (pressure 10MPa, ball diameter 2cm), is continuously and uniformly added to the molten pool to react and keep the temperature of the molten pool basically unchanged (maintaining time 6 min). While reacting, the composite thermal reduction is carried out to obtain a slag-gold mixed melt for slag-gold separation until the reaction ends. Finally, after cooling and slag removal, a titanium-aluminum alloy ingot is obtained.

[0057] The titanium-aluminum alloy prepared in this embodiment is composed of the following components by mass fraction: Al 31.35%, Ca 0.07%, Fe 0.13%, C 0.006%, N 0.036%, H 0.009%, O 0.026%, and Ti as the balance.

[0058] Example 3 The method for preparing the titanium-aluminum alloy in this embodiment utilizes AlCa56 alloy particles to prepare TiAl55 (atomic ratio) alloy, specifically employing the following steps: (1) Place rutile and potassium chlorate in a drying oven and dry them at 120°C for 14 hours.

[0059] (2) Rutile and aluminum-calcium alloy particles (Al:Ca=1:1.27) were mixed in a mass ratio of 1:1.42, and then mixed by adding mixing balls on a ball mill. The material-to-ball ratio was 5:1, the rotation speed was 280 r / min, and the ball milling time was 5 h.

[0060] (3) Preheat the mixture to 70°C for 50 min.

[0061] (4) Add an appropriate amount of potassium chlorate to the mixture and mix evenly (the mass ratio of titanium oxide to potassium chlorate is 1:0.28). Place the mixture in a ball mill mixer and mix for 50 min to obtain the mixture.

[0062] (5) Take out a portion of the material (accounting for 12% of the total material) and add it to the graphite reactor to initiate a rapid in-situ composite thermal reduction reaction to obtain a high-temperature molten pool (1500℃). The upper layer of the molten pool is a reducing slag and the lower layer is a titanium-aluminum alloy melt. Then, the remaining material, which has been pre-pressed into balls (pressure 12MPa, ball diameter 2cm), is continuously and uniformly added to the molten pool to react and keep the temperature of the molten pool basically unchanged (maintaining time 7 min). While reacting, the composite thermal reduction is carried out to obtain a slag-gold mixed melt for slag-gold separation until the reaction ends. Finally, after cooling and slag removal, a titanium-aluminum alloy ingot is obtained.

[0063] The titanium-aluminum alloy prepared in this embodiment is composed of the following components by mass fraction: Al 40.16%, Ca 0.08%, Fe 0.12%, C 0.008%, N 0.042%, H 0.005%, O 0.022%, and Ti as the balance.

[0064] Example 4 The method for preparing the titanium-aluminum alloy in this embodiment utilizes AlCa56 alloy particles to prepare TiAl65 (atomic ratio) alloy, specifically employing the following steps: (1) Place rutile and potassium chlorate in a drying oven and dry them at 120°C for 16 hours.

[0065] (2) Rutile and aluminum-calcium alloy particles (Al: Ca=1:2.33) were mixed in a mass ratio of 1:1.69, and then mixed by adding mixing balls in a ball mill. The material-to-ball ratio was 6:1, the rotation speed was 320 r / min, and the ball milling time was 6 h.

[0066] (3) Preheat the mixture to 80°C for 60 min.

[0067] (4) Add an appropriate amount of potassium chlorate to the mixture and mix evenly (the mass ratio of titanium oxide to potassium chlorate is 1:0.20). Place the mixture in a ball mill mixer and mix for 60 min to obtain the mixture.

[0068] (5) Take out a portion of the material (accounting for 10% of the total material) and add it to the graphite reactor to initiate a rapid in-situ composite thermal reduction reaction to obtain a high-temperature molten pool (1400℃). The upper layer of the molten pool is a reducing slag and the lower layer is a titanium-aluminum alloy melt. Then, the remaining material that has been pre-pressed into balls (pressure 20MPa, ball diameter 3cm) is continuously and uniformly added to the molten pool to react and keep the temperature of the molten pool basically unchanged (maintaining time 8 min). While reacting, the composite thermal reduction is carried out to obtain a slag-gold mixed melt for slag-gold separation until the reaction ends. Finally, after cooling and slag removal, a titanium-aluminum alloy ingot is obtained.

[0069] The titanium-aluminum alloy prepared in this embodiment is composed of the following components by mass fraction: Al 51.20%, Ca 0.01%, Fe 0.15%, C 0.010%, N 0.05%, H 0.005%, O 0.005%, and Ti as the balance.

[0070] (ii) Comparative Example Comparative Example 1 The preparation method of the titanium-aluminum alloy in this comparative example does not use aluminum-calcium alloy particles. The mass ratio of rutile, aluminum powder, slag-forming agent calcium oxide and potassium chlorate is 1:1.16:0.78:0.68. The contents not mentioned are exactly the same as in Example 3.

[0071] The titanium-aluminum alloy prepared in this comparative example is composed of the following components by mass fraction: Al 45.63%, Fe 0.28%, C 0.07%, N 0.07%, H 0.006%, O 0.68%, and Ti as the balance.

[0072] (III) Experimental Examples Inclusions in the alloy in Experiment Example 1 Metallographic analysis was performed on the TiAl alloys of Examples 2, 3, and 1, and the results are as follows: Figure 1 , Figure 2 , Figure 3 As shown.

[0073] As shown in the figure, the TiAl alloy prepared by the aluminothermic reduction method in the comparative example contains a large number of inclusions, and the inclusion particles are relatively large. In contrast, the inclusion content in the TiAl alloys prepared in Examples 2 and 3 is significantly reduced. The inclusion size in the alloy prepared in Example 2 is smaller, while the TiAl alloy prepared in Example 3 has virtually no inclusions.

[0074] Experimental Example 2 Under the same experimental conditions, the hardness and mechanical properties of the titanium-aluminum alloys in each embodiment and comparative example were tested, and the results are shown in Table 1. The relevant standards for the tests are as follows: Vickers hardness test according to GB / T 4340.1-2009 Metallic materials - Vickers hardness test - Part 1: Test method; mechanical property test according to GB / T 228.1-2021 Metallic materials - Tensile test - Part 1: Room temperature test method.

[0075] Table 1. Performance test results of titanium-aluminum alloys in each embodiment and comparative example. As shown in Table 1, the TiAl alloy prepared by this method has a hardness of 445~471HV, a yield strength of 461~482MPa, a fracture strength of 547~592MPa, a Young's modulus of 153~159MPa, and a titanium recovery rate of 91.5~95.8%. All of these indicators are superior to those of the traditional aluminothermic reduction method in the comparative example.

[0076] In summary, this method has the advantages of good gold slag separation effect, high metal recovery rate, high product quality, and high production efficiency. It can effectively solve the problem of ineffective removal of inclusions in the preparation of titanium-aluminum alloys by the aluminothermic method. At the same time, this method can effectively reduce the production cost of titanium-aluminum alloys and is suitable for large-scale industrial production.

[0077] Finally, it should be noted that the above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art can still modify the technical solutions described in the foregoing embodiments or make equivalent substitutions for some of the technical features. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A method for preparing a titanium-aluminum alloy, characterized in that, Includes the following steps: (1) Titanium oxide, reducing agent and in-situ slag-forming agent aluminum-calcium alloy particles, slag-forming agent and potassium chlorate in a mass ratio of 1:(0.92~1.69):(0~0.78):(0.2~0.68) are mixed evenly to obtain a mixture. (2) Take a portion of the mixed materials to initiate an in-situ composite thermal reduction reaction to obtain a high-temperature molten pool. The upper layer of the molten pool is a reducing slag and the lower layer is a titanium-aluminum alloy melt. Then, the remaining materials are pressed into balls and continuously and uniformly added to the high-temperature molten pool for reaction, so that the temperature of the high-temperature molten pool is maintained at 1400~1600℃. While reacting, the composite thermal reduction is carried out to obtain a slag-gold mixed melt for slag-gold separation until the reaction is completed. Without refining, titanium-aluminum alloy is directly obtained.

2. The method for preparing the titanium-aluminum alloy as described in claim 1, characterized in that, In step (2), a portion of the mixture accounts for 10-20% of the total mass of the mixture, and the remaining materials are pressed into balls with a diameter of 1-3 cm by a pressure of 5-20 MPa.

3. The method for preparing the titanium-aluminum alloy as described in claim 2, characterized in that, Step (2) The high-temperature molten pool is maintained at 1400~1600℃ for 5~8 minutes.

4. The method for preparing the titanium-aluminum alloy as described in claim 1, characterized in that, The mass content of Ca in the aluminum-calcium alloy particles is 10~56%; the slag-forming agent in step (1) is CaO; the mass ratio of titanium oxide, aluminum-calcium alloy particles, CaO and potassium chlorate is 1:(0.92~1.69):(0~0.55):(0.2~0.54).

5. The method for preparing the titanium-aluminum alloy as described in claim 4, characterized in that, The titanium oxide is titanium dioxide, rutile, high-titanium slag, or a mixture thereof; 0.1 mm ≤ titanium oxide particle size ≤ 2 mm; 0.5 mm ≤ aluminum-calcium alloy particle size ≤ 3 mm; 0.01 mm ≤ slag-forming agent particle size ≤ 2 mm; 0.1 mm ≤ potassium chlorate particle size ≤ 2 mm.

6. The method for preparing the titanium-aluminum alloy as described in claim 1, characterized in that, The raw materials, except for potassium chlorate, are ball-milled, mixed, and preheated. After preheating, they are mixed evenly with potassium chlorate to obtain the mixture.

7. The method for preparing the titanium-aluminum alloy as described in claim 6, characterized in that, The preheating temperature is 50~80℃ and the time is 30~60 min.

8. The method for preparing the titanium-aluminum alloy as described in claim 6, characterized in that, During ball milling, the rotation speed is 200~320 r / min, the material-to-ball ratio is (3~6):1, and the ball milling time is 3~6h.

9. A titanium-aluminum alloy prepared by any one of claims 1 to 8.

10. The titanium-aluminum alloy as described in claim 9, characterized in that, The titanium-aluminum alloy contains 20-55% Al, 0.01-0.08% Ca, and 0.005-0.03% O.

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