A method for producing an aluminum-tungsten-tantalum ternary master alloy

Abstract

This invention relates to the field of metallic materials technology, specifically to a method for producing an aluminum-tungsten-tantalum ternary master alloy. The method involves mixing tantalum pentoxide, aluminum powder, and potassium chlorate, placing the mixture in a molten pool, igniting it with a magnesium strip, and cooling it to obtain an aluminum-tantalum alloy ingot. After removing the surface alumina from the ingot, the ingot is machined into chips in a glove box for later use. Tungsten trioxide, aluminum powder, and the chipped aluminum-tantalum alloy are then mixed and placed in a vacuum aluminothermic furnace. The furnace is closed, a vacuum is created, and a mixture of magnesium and potassium permanganate is sprayed in. The mixture is ignited to initiate a vacuum aluminothermic reaction. After the reaction occurs, the vacuum level in the furnace is increased, and the furnace is cooled. The furnace is then opened, and the slag is removed to obtain the aluminum-tungsten-tantalum alloy ingot. This invention combines metallothermic reduction with vacuum aluminothermic processes to prepare the aluminum-tungsten-tantalum ternary alloy, producing an aluminum-tungsten-tantalum alloy with high homogeneity and low gaseous impurities. This solves the problems of high melting point, high density, and high gaseous impurity content in traditional aluminothermic reaction production methods.

Description

Technical Field

[0001] This invention relates to the field of metallic materials technology, and in particular to a method for producing an aluminum-tungsten-tantalum ternary master alloy. Background Technology

[0002] Refractory metals are metals with melting points above 2000℃. They include metals such as tungsten, tantalum, niobium, and molybdenum. Refractory metal alloys have high melting points, high strength under high temperature conditions, good corrosion resistance, and strong plasticity. They have a wide operating temperature range (1100~3320℃) and are important high-temperature structural materials for aerospace, such as Ta-25Ti-18Al-6.5W titanium alloy.

[0003] Currently, there are no relevant methods for preparing aluminum-tungsten-tantalum alloys, either domestically or internationally. Tungsten and tantalum alloys are mostly added to titanium alloys in the form of aluminum-tungsten or aluminum-tantalum. Due to the high melting point and density of aluminum-based tungsten and tantalum alloys, production methods are limited. The aluminothermic process is the main production method for aluminum-based refractory metal alloys, which involves mixing one or two metal oxides, aluminum powder, and slagging agents in a specific ratio, and producing alloy ingots through external furnace ignition. However, the alloy ingots produced by this method have a large density difference between aluminum and refractory metals (aluminum: 2.7 g / cm³). 3 Tungsten: 19.35 g / cm³ 3 Tantalum: 16.67 g / cm³ 3 After the aluminothermic reaction occurs, molten aluminum and refractory metals segregate due to their density difference. The segregation of refractory metals within a single ingot ranges from 3-8 wt%, resulting in a high oxygen content in the alloy, which hinders its application in high-end fields. Furthermore, the high melting point of aluminum-based refractory metal alloys prevents their refining in medium-frequency vacuum induction furnaces (crucible temperature limit 1800-1900℃) to reduce impurities and improve alloy quality. Summary of the Invention

[0004] In view of this, the purpose of this invention is to provide a method for producing an aluminum-tungsten-tantalum ternary master alloy. This method can produce a high-quality aluminum-tungsten-tantalum alloy, solving the problems of high inclusion content, high gaseous impurity content, and severe segregation in aluminum-tungsten-tantalum alloys produced by the aluminothermic method.

[0005] By producing aluminum-tantalum alloys using the aluminothermic method, after processing, the aluminum-tantalum alloy chips are mixed uniformly with tungsten and aluminum sources, and then a vacuum aluminothermic reaction occurs in a vacuum aluminothermic furnace. By controlling process parameters, the content of alumina inclusions and gaseous impurities in the alloy is reduced, and the alloy uniformity is improved, thus preparing a high-quality aluminum-tungsten-tantalum ternary master alloy (content: tungsten: 30-35wt%, tantalum: 30-40wt%, aluminum balance, silicon ≤0.15wt%, carbon ≤0.02wt%, oxygen ≤0.04wt%, nitrogen ≤0.02wt%), providing a guarantee for my country's high-end titanium alloy materials.

[0006] To achieve the above objectives, the present invention adopts the following technical solution:

[0007] A method for producing an aluminum-tungsten-tantalum ternary master alloy includes the following steps:

[0008] (1) Tantalum pentoxide, aluminum powder and potassium chlorate are mixed and placed in a molten pool, ignited with magnesium strips, and cooled to obtain aluminum-tantalum alloy ingots. The alloy ingots are then machined into chips in a glove box for later use.

[0009] (2) The aluminum-tantalum alloy chips prepared in step (1) are mixed with tungsten trioxide and aluminum powder and then placed in a vacuum aluminothermic furnace to undergo a vacuum aluminothermic reaction. After the reaction occurs, the vacuum degree in the furnace is increased, the temperature is lowered, and the slag is removed to obtain aluminum-tungsten-tantalum alloy ingots, namely aluminum-tungsten-tantalum ternary intermediate alloy.

[0010] Preferably, the theoretical tantalum content in the aluminum-tantalum alloy is 70wt% to 80wt% to facilitate the processing of aluminum-tantalum alloy shavings. Because aluminum-tantalum alloy has high toughness and viscosity, it cannot be crushed into particles. Therefore, shavings of aluminum-tantalum alloy are mixed with aluminum powder and tungsten trioxide materials through machining to produce aluminum-tungsten-tantalum alloy.

[0011] Furthermore, the mass ratio of aluminum powder to tantalum pentoxide is (0.6–0.8):1, and the mass ratio of potassium chlorate to tantalum pentoxide is 0.4:1. By controlling the proportions and amounts added, the thermal effect per unit furnace charge can be maintained between 720 and 850 kcal / kg, thus ensuring a stable reaction.

[0012] Furthermore, the molten pool material is corundum, which has stable properties and good thermal shock resistance, preventing the introduction of impurity elements such as carbon and silicon due to molten pool material issues.

[0013] Furthermore, the surface of the aluminum-tantalum alloy ingot is subjected to sandblasting treatment for 60-150 minutes to remove surface inclusions, ensure that the aluminum oxide layer on the alloy surface is fully removed, and prevent the aluminum oxide layer from entering the aluminum-tungsten-tantalum alloy.

[0014] Furthermore, argon is used as a protective gas in the glove box. The aluminum-tantalum alloy is machined under argon protection to prevent the alloy from oxidizing and nitriding in the air due to overheating of the cutting tool.

[0015] Furthermore, the particle size of the aluminum-tantalum alloy chips is less than 0.5cm*0.5cm*0.05cm to prevent excessively large particles from affecting the uniformity of mixing and thus the uniformity of the aluminum-tungsten-tantalum alloy; the cutting tool is of grade W2Mo9Cr4VCo8, and the chip turning speed is 0.5-5cm / s to prevent the cutting tool components from entering the aluminum-tantalum alloy chips and introducing Cr, V, and Co impurities due to excessively fast chip turning speed.

[0016] Preferably, in step (2), the mass ratio of tungsten trioxide, aluminum powder and shaving aluminum-tantalum alloy is (7-9):(3-9):(7-12) to ensure the grade of the aluminum-tungsten-tantalum alloy.

[0017] In addition, the crucible in the vacuum aluminothermic furnace is made of copper with a radius of 3 to 6.5 cm. Copper crucibles have a fast heat conduction rate. By controlling the crucible radius to adjust the thickness of the alloy ingot, the metal reduction and alloying in the aluminothermic reaction are completed, and the temperature is rapidly reduced.

[0018] Furthermore, the vacuum aluminothermic reaction is operated as follows:

[0019] Turn off the furnace body and turn on the mechanical pump to evacuate to a vacuum degree of <500Pa. Spray a mixture of magnesium and potassium permanganate, turn on the condenser water at a temperature of 50-70℃, circulate for 5-10 minutes, and then ignite the material to initiate a vacuum aluminothermic reaction.

[0020] It should be noted that vacuuming prevents nitrogen from entering the alloy, and since the reduction process is not yet complete at the start of the reaction, hot water at 50-70℃ is used to prevent the alloy from cooling down rapidly.

[0021] Furthermore, the magnesium powder in the magnesium and potassium permanganate mixture accounts for 70-80 wt% of the total weight, and the powder spraying time is 3-6 seconds. Controlling the ratio of magnesium powder and potassium permanganate and the powder spraying time can ensure successful ignition.

[0022] Preferably, the Roots pump is activated 15-25 seconds after the vacuum aluminothermic reaction occurs to increase the vacuum level to below 50 Pa. After the reaction, the alloy moves towards the bottom of the crucible, and the reduction product, alumina, moves towards the top of the copper crucible. After the upper alumina solidifies, the furnace gas generated during the aluminothermic reaction accumulates between the alumina and the aluminum-tungsten-tantalum alloy, forming a high-pressure region (e.g., Figure 1 This increases the surface tension and hydrostatic pressure of the alloy solution, making it difficult for alumina inclusions in the alloy to separate from the molten alloy. During the 15-25 seconds of the reaction, the upper alumina has not yet solidified. Increasing the vacuum level prevents the alumina layer from solidifying and sealing, disrupts the formation of the high-pressure zone, accelerates the separation of the alloy from the alumina inclusions, and improves the alloy quality.

[0023] Preferably, the cooling operation is as follows: after the vacuum aluminothermic reaction has occurred for 60-75 seconds, the metal thermal reduction and alloying process is basically completed. The cooling water source of the water-cooled copper crucible is replaced, and the cooling water temperature is <20℃. This accelerates the heat exchange rate inside the crucible and prevents element segregation caused by the density difference of tungsten and tantalum moving to the bottom of the alloy melt.

[0024] Compared with the prior art, the beneficial effects of the present invention are:

[0025] This invention combines metallothermic reduction and vacuum aluminothermic processes to prepare aluminum-tungsten-tantalum ternary alloys, producing aluminum-tungsten-tantalum alloys with high uniformity and low gaseous impurities. It solves the problems of high melting point and high density ternary alloy production with alumina inclusions and high gaseous impurity content in traditional aluminothermic reaction production, and provides a new approach for the production of high melting point and high density ternary master alloys. Attached Figure Description

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

[0027] Figure 1 This is a simplified diagram of the materials inside the copper crucible for vacuum aluminothermic reaction.

[0028] Figure 2 This is a multi-point sampling diagram of an aluminum-tungsten-tantalum alloy. Detailed Implementation

[0029] The technical solutions in the embodiments of the present invention will be clearly and completely described below. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of the present invention.

[0030] Unless otherwise stated, the technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application pertains; other experimental methods and technical means not specifically mentioned herein refer to experimental methods and technical means commonly used by one of ordinary skill in the art.

[0031] To better illustrate the content of this application, numerous specific details are provided in the following detailed embodiments. Those skilled in the art should understand that this application can be implemented even without certain specific details. In the embodiments, some methods, means, instruments, and devices well-known to those skilled in the art are not described in detail in order to highlight the main points of this application.

[0032] Without conflict, the technical features disclosed in the embodiments of this application can be combined arbitrarily, and the resulting technical solution belongs to the content disclosed in the embodiments of this application.

[0033] To better understand the present invention, the following embodiments are provided for further detailed description of the present invention, but they should not be construed as limiting the present invention. Any non-essential improvements and adjustments made by those skilled in the art based on the above-described invention are also considered to fall within the protection scope of the present invention.

[0034] Example 1

[0035] A method for producing an aluminum-tungsten-tantalum ternary master alloy includes the following steps:

[0036] 100 kg of tantalum pentoxide, 69 kg of aluminum powder, and 40 kg of potassium chlorate were mixed evenly in proportion and placed in a molten pool made of corundum. The mixture was ignited with magnesium strips and cooled to obtain 121.5 kg of aluminum-tantalum alloy ingot. The alloy ingot was sandblasted for 65 minutes to remove the aluminum oxide layer on the surface of the alloy ingot, and the surface of the alloy ingot had a metallic luster, resulting in 119.4 kg of aluminum-tantalum alloy ingot. The aluminum-tantalum alloy ingot was transferred into a glove box, evacuated, and then purged with argon gas to atmospheric pressure. The cutting tool was W2Mo9Cr4VCo8, and the speed was 1.5 cm / s, resulting in aluminum-tantalum alloy chips with a particle size of 0.4 cm * 0.3 cm * 0.04 cm.

[0037] 40.1 kg of tungsten trioxide, 30.5 kg of aluminum powder, and 46.7 kg of aluminum-tantalum alloy scrap were thoroughly mixed and then placed into a water-cooled crucible in a vacuum aluminothermic furnace. The furnace body was closed, the mechanical pump was turned on, and the furnace pressure was evacuated to 450 Pa. The circulating water was turned on at a temperature of 68°C and circulated for 8 minutes. A mixture of magnesium (75 wt%) and potassium permanganate was sprayed for 4.5 seconds, and the material was ignited to initiate a vacuum aluminothermic reaction. After 20 seconds of reaction, the Roots pump was turned on to bring the vacuum to 35 Pa. After 70 seconds of reaction, the temperature was lowered, the condensate water source was replaced, and the water temperature was 15°C. After 1.5 hours of cooling, the furnace was opened, the slag was removed, and 98.9 kg of aluminum-tungsten-tantalum alloy ingots were obtained.

[0038] For alloy ingots Figure 2 The experimental results from multiple sampling points are shown in the table below:

[0039]

[0040] The table above shows that the segregation of W and Ta elements in the aluminum-tungsten-tantalum alloy is less than 0.8 wt%, and the levels of impurity elements such as oxygen and nitrogen are much lower than those in conventional aluminum-tungsten-tantalum alloys (for example, the oxygen and nitrogen content in Comparative Example 1 is significantly higher than that in the aluminum-tungsten-tantalum alloy of Example 1). The alloy has high purity and good uniformity.

[0041] Example 2

[0042] A method for producing an aluminum-tungsten-tantalum ternary master alloy includes the following steps:

[0043] 100 kg of tantalum pentoxide, 73 kg of aluminum powder, and 40 kg of potassium chlorate were mixed evenly in a certain proportion and placed in a molten pool made of corundum. The mixture was ignited with magnesium strips and cooled to obtain 117.1 kg of aluminum-tantalum alloy ingot. The alloy ingot was sandblasted for 68 minutes to remove the aluminum oxide layer on the surface of the alloy ingot, and the surface of the alloy ingot had a metallic luster, resulting in 114.2 kg of aluminum-tantalum alloy ingot. The aluminum-tantalum alloy ingot was transferred into a glove box, evacuated, and then purged with argon gas to atmospheric pressure. The cutting tool was W2Mo9Cr4VCo8, and the speed was 2.5 cm / s, resulting in aluminum-tantalum alloy chips with a particle size of 0.4 cm * 0.3 cm * 0.03 cm.

[0044] 39.1 kg of tungsten trioxide, 26 g of aluminum powder, and 52.1 kg of aluminum-tantalum alloy scrap were thoroughly mixed and then placed into a water-cooled crucible in a vacuum aluminothermic furnace. The furnace body was closed, the mechanical pump was turned on, and the furnace pressure was evacuated to 400 Pa. The circulating water was turned on at 70 °C and circulated for 5 min. A mixture of magnesium (75 wt%) and potassium permanganate was sprayed for 4.5 s, and the material was ignited to initiate a vacuum aluminothermic reaction. After 19 s of reaction, the Roots pump was turned on to bring the vacuum to 39 Pa. After 70 s of reaction, the temperature was lowered, the condensate water source was replaced, and the water temperature was 18 °C. After 1.6 h of cooling, the furnace was opened, the slag was removed, and 99.1 kg of aluminum-tungsten-tantalum alloy ingots were obtained.

[0045] For alloy ingots Figure 2 The experimental results from multiple sampling points are shown in the table below:

[0046]

[0047] The table above shows that the elements in the aluminum-tungsten-tantalum alloy have good uniformity, low segregation, and the impurity elements oxygen and nitrogen are much lower than in conventional aluminum-tungsten-tantalum alloys, indicating high alloy purity.

[0048] To further demonstrate the beneficial effects of the present invention and to better understand it, the technical features disclosed in the present invention are further illustrated by the following comparative examples, but these should not be construed as limiting the present invention. Other improvements made by those skilled in the art based on the above description of the invention, without inventive effort, are also considered to fall within the protection scope of the present invention.

[0049] Comparative Example 1

[0050] 40.8 kg of tantalum pentoxide, 40.3 kg of tungsten trioxide, 69 kg of aluminum powder, and 16.32 kg of potassium chlorate were mixed evenly in a specific ratio and then placed in a molten pool made of corundum. The mixture was ignited with a magnesium strip, and after cooling, 97.4 kg of aluminum-tungsten-tantalum alloy ingots were obtained.

[0051] For alloy ingots Figure 2 The experimental results from multiple sampling points are shown in the table below:

[0052]

[0053]

[0054] The table above shows that the W element segregation in the aluminum-tungsten-tantalum alloy is about 3.8 wt%, and the Ta element segregation is about 7 wt%. The alloy ingot has severe segregation, and the content of impurity elements oxygen and nitrogen is much higher than that in Example 1, indicating poor alloy purity.

[0055] The above description of the disclosed embodiments enables those skilled in the art to make or use the invention. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the invention. Therefore, the invention is not to be limited to the embodiments shown herein, but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A method for producing an aluminum-tungsten-tantalum ternary master alloy, characterized in that, Includes the following steps: (1) Tantalum pentoxide, aluminum powder and potassium chlorate are mixed and placed in a molten pool, ignited with magnesium strips, and cooled to obtain aluminum-tantalum alloy ingots. The alloy ingots are then machined into chips in a glove box for later use. (2) The aluminum-tantalum alloy shavings prepared in step (1) are mixed with tungsten trioxide and aluminum powder and then loaded into a vacuum aluminothermic furnace to undergo a vacuum aluminothermic reaction. After the reaction occurs, the vacuum degree in the furnace is increased, the temperature is lowered, and the slag is removed to obtain an aluminum-tungsten-tantalum alloy ingot, namely an aluminum-tungsten-tantalum ternary intermediate alloy. In step (2), the mass ratio of tungsten trioxide, aluminum powder and shaving aluminum-tantalum alloy is (7~9):(3~9):(7~12); The vacuum aluminothermic reaction is operated as follows: Turn off the furnace body and turn on the mechanical pump to evacuate to a vacuum degree of <500 Pa. Spray a mixture of magnesium and potassium permanganate, turn on the condenser water at a temperature of 50-70 ℃, circulate for 5-10 minutes, and then ignite the material to induce a vacuum aluminothermic reaction. The Roots pump is turned on 15-25 seconds after the vacuum aluminothermic reaction occurs to increase the vacuum to below 50 Pa. The cooling operation is as follows: after the vacuum aluminothermic reaction has occurred for 60-75 seconds, replace the water source for the water-cooled copper crucible to cool it. The temperature of the cooling water should be <20℃.

2. The method for producing an aluminum-tungsten-tantalum ternary master alloy according to claim 1, characterized in that, The theoretical tantalum content in the aluminum-tantalum alloy ingot is 70 wt%~80 wt%, the mass ratio of aluminum powder to tantalum pentoxide is (0.6~0.8):1, and the mass ratio of potassium chlorate to tantalum pentoxide is 0.4:

1.

3. The method for producing an aluminum-tungsten-tantalum ternary master alloy according to claim 1 or 2, characterized in that, The surface of the aluminum-tantalum alloy ingot is sandblasted for 60-150 minutes.

4. The method for producing an aluminum-tungsten-tantalum ternary master alloy according to claim 3, characterized in that, Argon is used as the protective gas in the glove box, and the particle size of the aluminum-tantalum alloy chips is less than 0.5 cm*0.5 cm*0.05 cm. The cutting tool is of grade W2Mo9Cr4VCo8, and the chip turning speed is 0.5-5 cm / s.

5. The method for producing an aluminum-tungsten-tantalum ternary master alloy according to claim 1, characterized in that, The magnesium powder in the magnesium and potassium permanganate mixture is 70-80 wt% by weight, and the spraying time is 3-6 s.

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