CN115838876A - A kind of preparation method of niobium-titanium-aluminum alloy ingot - Google Patents

Abstract

The invention discloses a preparation method of a niobium-titanium-aluminum-based alloy ingot, which comprises the following steps: 1. crushing the niobium-titanium cast ingot to obtain niobium-titanium fragments, and carrying out acid pickling and vacuum annealing treatment to obtain pretreated niobium-titanium fragments; 2. mixing part of the pretreated niobium-titanium scraps with titanium sponge to obtain a mixture A, and mixing the rest of the pretreated niobium-titanium scraps with an aluminum-niobium alloy and other intermediate alloys to obtain a mixture B; 3. distributing and pressing the mixture A serving as an upper layer and a lower layer and the mixture B serving as an intermediate layer to obtain an electrode block; 4. assembling and welding the electrode blocks to obtain an electrode rod; 5. the electrode rod is subjected to three times of vacuum consumable arc melting. According to the invention, niobium-titanium scraps are pretreated, and the design of mixing niobium-titanium scraps with other raw materials and pressing and distributing the materials is combined, so that micro-area segregation and inclusion of Nb element and Al element loss are avoided, the uniformity and content accuracy of alloy components in the niobium-titanium-aluminum-based alloy ingot are improved, and the requirement of industrial production is met.

Description

A kind of preparation method of niobium-titanium-aluminum alloy ingot

technical field

The invention belongs to the technical field of niobium alloy preparation, and in particular relates to a method for preparing a niobium-titanium-aluminum-based alloy ingot.

Background technique

Compared with γ-TiAl alloy, Ti-AlNb alloy has higher strength and better fracture toughness, and its excellent performance meets the urgent requirements of future aero-engines for lightweight high-temperature structural materials with high specific strength and high specific stiffness. It is of great significance to reduce the weight of the aircraft, improve fuel efficiency and high temperature service performance. The mechanical and thermal forming properties of niobium-titanium-aluminum-based alloys are seriously affected by the uniformity of alloy composition and structure, and the content of impurity elements. Therefore, proper raw materials and smelting methods are selected to prepare accurate and pure components, uniform distribution of alloy elements, and dense solidified structure. Ingot casting with low content of interstitial elements O, N, and H is the prerequisite to ensure the mechanical properties of niobium-titanium-aluminum-based alloys. From the smelting of Ti-Al-Nb ternary alloys, in the smelting process of niobium-titanium-aluminum-based alloys, the Al element with low density and low melting point volatilizes greatly during the smelting process. The accuracy and uniformity of alloy composition is difficult to be guaranteed.

Contents of the invention

The technical problem to be solved by the present invention is to provide a method for preparing a niobium-titanium-aluminum-based alloy ingot for the above-mentioned deficiencies in the prior art. In this method, niobium-titanium scraps are used as raw materials and pretreated, combined with mixing niobium-titanium scraps with other raw materials and performing a three-layer cloth design, which reduces the amount of impurity elements introduced and avoids the microscopic contamination of Nb elements during the smelting process. In order to avoid segregation and inclusions in the zone, the aluminum-niobium alloy with a lower melting point is selected as the intermediate alloy added with aluminum and niobium elements, which reduces the loss of Al elements with low density and low melting point during the smelting process, and improves the alloy composition in the niobium-titanium-aluminum-based alloy ingot. Uniformity and content accuracy solve the problem of uneven distribution of alloying elements in niobium-titanium-aluminum-based alloys.

In order to solve the above-mentioned technical problems, the technical solution adopted in the present invention is: a method for preparing a niobium-titanium-aluminum-based alloy ingot, which is characterized in that the method comprises the following steps:

Step 1, crushing the niobium-titanium ingot to obtain niobium-titanium debris, pickling the niobium-titanium debris and then performing vacuum annealing treatment to obtain pretreated niobium-titanium debris;

Step 2: Mix some of the pretreated niobium-titanium scrap obtained in step 1 with sponge titanium to obtain mixture A, and mix the pretreated niobium-titanium scrap obtained in the remaining step 1 with aluminum-niobium alloy and other master alloys to obtain a mixture B;

Step 3, the mixture A obtained in step 2 is used as the upper layer and the lower layer, and the mixture B is used as the middle layer to carry out cloth in a pressing mold, and then press to obtain an electrode block;

Step 4, performing assembly welding on the electrode block obtained in step 3, and repairing welding with a titanium thin plate at the assembly welding position to obtain an electrode rod;

Step 5. Place the electrode rod obtained in step 4 as a consumable electrode in a vacuum consumable electric arc furnace for one smelting to obtain an ingot, and then connect the four ingots with flat ends and place them in a vacuum Two electrodes are assembled and welded in the consumable electric arc furnace, and two secondary ingots are obtained by secondary melting of the two electrodes, and then the two secondary ingots are connected head to tail and placed in a vacuum consumable One electrode is assembled and welded in an electric arc furnace, and one electrode is melted three times to obtain three ingots, that is, niobium-titanium-aluminum-based alloy ingots.

In the present invention, the niobium-titanium scrap is firstly pretreated, and the surface oxide impurities are removed by pickling, combined with vacuum annealing treatment to soften the niobium-titanium scrap so as to have higher ductility, and reduce some gas impurities in the niobium-titanium scrap The content of elements such as O, N, and H, while further removing oil stains on the surface of niobium-titanium debris and adhering cutting fluid and other impurities, to obtain niobium-titanium debris with lower impurity element content, which is conducive to the realization of the subsequent pressing electrode block process Secondly, the present invention adopts niobium-titanium scrap, aluminum-niobium alloy as the raw material of niobium element in the target product niobium-titanium-aluminum alloy ingot, by pretreatment niobium-titanium scrap is divided into two parts, a part is mixed with sponge titanium to obtain mixture A , a part of which is mixed with aluminum-niobium alloy and other intermediate alloys to obtain mixture B, and then the mixture A and mixture B are pressed into electrode blocks to prepare the target product, so that the niobium-containing raw materials are dispersed in various positions of the electrode blocks, and the niobium-titanium-aluminum The distribution uniformity of the niobium element in the ingot of the niobium-based alloy avoids the micro-segregation and inclusion of the Nb element due to the high content, thereby improving the uniformity and content accuracy of the alloy composition in the niobium-titanium-aluminum-based alloy ingot; again, this The invention adopts aluminum-niobium alloy and other intermediate alloys as the raw materials of aluminum elements in the target product niobium-titanium-aluminum-based alloy ingot, and puts all the raw materials of aluminum elements into mixture B, and uses mixture A as The wrapping material is laid on the upper and lower layers, and the mixture B containing aluminum raw materials is wrapped between the upper and lower layers as an intermediate layer, which greatly reduces the volatilization of Al elements with low density and low melting point in the subsequent smelting process, and further improves the niobium titanium aluminum The uniformity and content accuracy of the alloy composition in the base alloy ingot, and at the same time avoiding the edge arc caused by the two master alloys of aluminum-niobium alloy and other master alloys, resulting in uneven alloy composition in the niobium-titanium-aluminum-based alloy ingot, This ensures the smooth progress of the subsequent smelting process.

The above-mentioned method for preparing a niobium-titanium-aluminum-based alloy ingot is characterized in that the particle size of the niobium-titanium debris in step 1 is 1 mm to 3 mm, and the conditions for the vacuum annealing treatment are: the degree of vacuum is less than 5×10 ^-2 MPa, the temperature is 900℃～950℃, and the time is more than 60min. The present invention adopts the scraps produced after processing niobium-titanium ingots, i.e., niobium-titanium scraps, as raw materials for niobium elements, which reduces the preparation cost, and reduces the particle size of the niobium-titanium scraps and other master alloys by controlling the particle size of the niobium-titanium scraps to 1 mm to 3 mm. After mixing, the distribution of each alloy in the electrode block is more uniform, and it is not easy to produce inclusions and composition segregation during the melting process.

The above-mentioned method for preparing a niobium-titanium-aluminum-based alloy ingot is characterized in that the sponge titanium described in step 2 is grade 0 sponge titanium with a particle size of 3 mm to 12.7 mm, and the mixture A is obtained by mixing with a mixer for 3 minutes, The mixture B was obtained by mixing with a mixer for 5 minutes. The 0-grade sponge titanium with a particle size of 3 mm to 12.7 mm used in the present invention has a spongy pore structure and a small volume. After the pressing treatment, the niobium-titanium debris is completely adhered to the surface, and the occurrence of niobium-titanium debris during the smelting process is avoided. The falling of debris causes composition segregation. At the same time, the present invention uses a mixer for mixing treatment, which is beneficial to fully mixing and uniformly mixing the components in the mixture A and the mixture B, and further facilitating the uniform distribution of the elements in the niobium-titanium-aluminum-based alloy ingot.

The above-mentioned method for preparing a niobium-titanium-aluminum-based alloy ingot is characterized in that the mass of the mixture A of the upper layer and the lower layer in step 3 is equal. In the present invention, by controlling the quality of the mixture A of the upper layer and the lower layer to be equal, the mixture B containing aluminum raw materials is fully wrapped between the mixture A of the upper layer and the lower layer, which ensures the wrapping effect and effectively reduces the low density and low melting point in the subsequent smelting process. The volatilization of the Al element improves the uniformity and content accuracy of the alloy composition in the niobium-titanium-aluminum-based alloy ingot.

The above-mentioned method for preparing a niobium-titanium-aluminum-based alloy ingot is characterized in that the welding process described in step 4 is performed by copper electrode plasma arc welding in a vacuum welding box. The invention uses a vacuum-filled argon atmosphere as the welding environment, reduces the oxidation of solder joints during welding, improves the firmness of the solder joints during electrode block welding, uses copper electrode welding torches to completely avoid the problem of tungsten inclusions in titanium alloys, and has a welding heat-affected zone Small size, small welding deformation and high welding quality.

Compared with the prior art, the present invention has the following advantages:

1. The present invention uses niobium-titanium scraps as raw materials. By pretreating the niobium-titanium scraps, it is beneficial to carry out the pressing process and reduce the introduction of impurity elements. In combination, the niobium-titanium scraps are divided into two parts, and respectively combined with titanium sponge , aluminum-niobium alloy and other intermediate alloys, so that the niobium element is evenly distributed, and the three-layer cloth method is used to reduce the volatilization of Al elements with low density and low melting point during the smelting process. Through the common control of the above-mentioned links, Nb The micro-segregation and inclusion of elements and the loss of Al element improve the uniformity and content accuracy of the alloy composition in the niobium-titanium-aluminum-based alloy ingot.

2. The niobium-titanium-aluminum-based alloy ingot prepared by the present invention increases the mass content of the niobium element in the ingot to more than 40% under the premise of ensuring uniform overall composition, and the distribution of each alloy component in the ingot is even and fluctuates relatively Small, no defects such as niobium inclusions, good surface quality, and meet the requirements of industrial production for uniform distribution of components in niobium-titanium-aluminum alloy homogeneous ingots.

3. The present invention adopts niobium-titanium scraps as one of the sources of niobium elements, and selects aluminum-niobium alloy as the source of the remaining niobium elements and some aluminum elements. Because the melting point of aluminum-niobium alloy is low, it is easier to distribute evenly in the smelting process, reducing the The risk of alloy composition segregation, while selecting other master alloys and sponge titanium to supplement other alloy components, ensures the uniform distribution of alloy components in the niobium-titanium-aluminum-based alloy ingot.

4. The present invention further synergistically improves the alloy in the niobium-titanium-aluminum-based alloy ingot by pretreating the niobium-titanium debris, combining with controlling its particle size, and controlling the distribution method of the pressed electrode block, the electrode block welding method and the smelting method. Uniform distribution of components, avoiding metallurgical defects, and improving the surface quality of ingots.

5. The present invention adopts the method of three-layer cloth to prepare the electrode block. By using the mixture of niobium-titanium scrap and sponge titanium as the upper and lower wrapping materials, and the mixture of the aluminum-containing master alloy as the middle layer, it is ensured that the aluminum-containing master alloy is covered. Complete coating reduces the volatilization of Al element during the smelting process, avoids the edge arc caused by the falling of the middle layer, and ensures the smooth progress of the smelting process.

6. The present invention adopts three times of vacuum consumable arc smelting, and the next smelting is carried out by welding ingots of each smelting ingot in a vacuum consumable arc furnace in turn, further avoiding the introduction of impurity elements, and improving the niobium-titanium-aluminum-based alloy The alloy composition of the ingot is uniform, and the process is simple and easy to control.

7. The production process of the present invention is simple, the cost is low, and it is easy to realize industrialized production.

The technical solutions of the present invention will be described in further detail below through examples.

Detailed ways

Example 1

This embodiment includes the following steps:

Step 1. Crushing the niobium-titanium ingots to obtain niobium-titanium chips with a particle size of 1 mm to 3 mm. Pickling the niobium-titanium chips and putting them into a vacuum annealing furnace, heating them under the condition of a vacuum degree of 4.5×10 ^-2 MPa To 900 ℃ ~ 950 ℃ and hold for 70 minutes for vacuum annealing treatment, to obtain pretreated niobium titanium debris;

Step 2. Part of the pretreated niobium-titanium scrap obtained in step 1 and 0-grade sponge titanium with a particle size of 3mm to 12.7mm were mixed with a mixer for 3 minutes to obtain mixture A, and the remaining pretreated niobium-titanium scrap obtained in step 1 Chips, aluminum-niobium alloy and aluminum-molybdenum alloy were mixed with a mixer for 5 minutes to obtain mixture B;

Step 3. Divide the mixture A obtained in step 2 into two parts of equal quality, mixture A ₁ and mixture A _2. First, pour mixture A ₁ into the pressing mold and spread the cloth to form the lower layer, and then pour mixture B into the pressing mold. Spread the cloth in the mold to form the middle layer, then pour the mixture _A2 into the pressing mold and spread the cloth to form the upper layer, and press it with a hydraulic press to obtain electrode blocks with a unit weight of 15 kg, a total of 20 blocks;

Step 4. Divide the 20 electrode blocks obtained in step 3 into 4 groups, use vacuum welding box copper electrode plasma arc welding for group welding, and use titanium thin plate repair welding at the group welding position, and weld every 5 electrode blocks 1 electrode rod was obtained, and a total of 4 electrode rods were obtained; during the assembly welding process, the electrode blocks were put into the vacuum welding box and placed evenly and symmetrically, and the fixture was adjusted and tightened. When it exceeds 3Pa, test the air leakage rate to ensure that the air leakage rate does not exceed 2.5Pa·min ^-1 , then fill it with argon to a pressure of 45kPa and start welding, and the welding current used is 320A~370A, and the welding voltage is 50V~70V;

Step 5. Place the four electrode rods obtained in step 4 as consumable electrodes in a vacuum consumable electric arc furnace for one smelting. A crucible with a diameter of φ220mm is used for one smelting. The smelting flow is 5kA to 9kA, and the smelting voltage is 29V ~ 32V, melting vacuum degree is 1.0Pa ~ 3.0Pa, get 4 primary ingots, then connect the 4 primary ingots with flat head and tail in sequence and place them in a vacuum consumable electric arc furnace for welding to get 2 ingots electrodes, and carry out secondary melting on the two electrodes. The secondary melting uses a crucible with a diameter of φ280mm, the melting flow is 5kA~10kA, the melting voltage is 29V~33V, and the melting vacuum is 0.5Pa~1.6Pa, and two secondary Ingot casting, then two secondary ingots are connected head to tail and placed in a vacuum consumable arc furnace for assembly welding to obtain an electrode, and one electrode is smelted three times, and a crucible with a diameter of φ360mm is used for the third smelting , the smelting flow is 7kA～12kA, the smelting voltage is 33V～36V, the smelting vacuum is 0.3Pa～0.9Pa, after cooling for 1h, three ingots are obtained, that is, the niobium-titanium-aluminum base with the nominal composition of Ti-20Al-28Nb-1Mo alloy ingot.

The niobium-titanium-aluminum-based alloy ingot prepared in this example was flat-headed and skinned, and then the ingot was sawed in the middle and samples were taken from the upper, middle and lower parts of the ingot to detect the chemical composition. The results showed that the niobium-titanium The mass contents of niobium in the upper, middle and lower parts of the aluminum-based alloy ingot are 47.02%, 46.07% and 46.08% respectively, the absolute value of the fluctuation deviation of the composition is less than 1%, and the composition uniformity of each alloy is good. At the same time, after further testing, the niobium-titanium-aluminum-based alloy ingot prepared in this example has no defects such as niobium inclusions, and meets the requirements of large-scale industrial production on the uniformity of alloy composition distribution of the niobium-titanium-aluminum-based alloy ingot.

Example 2

This embodiment includes the following steps:

Step 1. Crushing the niobium-titanium ingots to obtain niobium-titanium chips with a particle size of less than 3mm, pickling the niobium-titanium chips and putting them into a vacuum annealing furnace, and heating ^them to Vacuum annealing at 900°C and holding for 60 minutes to obtain pretreated niobium-titanium scrap;

Step 2. Part of the pretreated niobium-titanium scrap obtained in step 1 and 0-grade sponge titanium with a particle size of 3mm to 12.7mm were mixed with a mixer for 3 minutes to obtain mixture A, and the remaining pretreated niobium-titanium scrap obtained in step 1 Chips, aluminum-niobium alloy and aluminum-molybdenum alloy were mixed with a mixer for 5 minutes to obtain mixture B;

Step 3. Divide the mixture A obtained in step 2 into two parts, namely mixture A ₁ and mixture A ₂ . First, pour mixture A ₁ into the pressing mold and spread the cloth to form the lower layer, and then pour mixture B into the pressing mold to spread The flat cloth forms the middle layer, and then the mixture _A2 is poured into the pressing mold to flatten the cloth to form the upper layer, which is pressed by a hydraulic press to obtain 20 electrode blocks with a single weight of 15 kg;

Step 4. Divide the 20 electrode blocks obtained in step 3 into 4 groups, use vacuum welding box copper electrode plasma arc welding for group welding, and use titanium thin plate repair welding at the group welding position, and weld every 5 electrode blocks 1 electrode rod was obtained, and a total of 4 electrode rods were obtained; during the assembly welding process, the electrode blocks were put into the vacuum welding box and placed evenly and symmetrically, and the fixture was adjusted and tightened. When it exceeds 3Pa, test the air leakage rate to ensure that the air leakage rate does not exceed 2.5Pa·min ^-1 , then fill it with argon to a pressure of 45kPa and start welding, and the welding current used is 320A~370A, and the welding voltage is 50V~70V;

Step 5. Place the four electrode rods obtained in step 4 as consumable electrodes in a vacuum consumable electric arc furnace for one smelting. A crucible with a diameter of φ220mm is used for one smelting. The smelting flow is 5kA to 9kA, and the smelting voltage is 29V ~ 32V, melting vacuum degree is 1.0Pa ~ 3.0Pa, get 4 primary ingots, then connect the 4 primary ingots with flat head and tail in sequence and place them in a vacuum consumable electric arc furnace for welding to get 2 ingots electrodes, and carry out secondary melting on the two electrodes. The secondary melting uses a crucible with a diameter of φ280mm, the melting flow is 5kA~10kA, the melting voltage is 29V~33V, and the melting vacuum is 0.5Pa~1.6Pa, and two secondary Ingot casting, then two secondary ingots are connected head to tail and placed in a vacuum consumable arc furnace for assembly welding to obtain an electrode, and one electrode is smelted three times, and a crucible with a diameter of φ360mm is used for the third smelting , the smelting flow is 7kA~12kA, the smelting voltage is 33V~36V, the smelting vacuum is 0.3Pa~0.9Pa, after cooling for 1h, three ingots are obtained, that is, the niobium titanium aluminum with the nominal composition of Ti-16Al-30Nb-0.5Mo base alloy ingot.

The niobium-titanium-aluminum-based alloy ingot prepared in this example was flat-headed and skinned, and then the ingot was sawed in the middle and samples were taken from the upper, middle and lower parts of the ingot to detect the chemical composition. The results showed that the niobium-titanium The mass contents of niobium in the upper, middle and lower parts of the aluminum-based alloy ingot are 47.56%, 48.01% and 47.92% respectively, the absolute value of the fluctuation deviation of the composition is less than 1%, and the composition uniformity of each alloy is good. At the same time, after further testing, the niobium-titanium-aluminum-based alloy ingot prepared in this example has no defects such as niobium inclusions, and meets the requirements of large-scale industrial production on the uniformity of alloy composition distribution of the niobium-titanium-aluminum-based alloy ingot.

Example 3

This embodiment includes the following steps:

Step 1. Crushing the niobium-titanium ingots to obtain niobium-titanium chips with a particle size of less than 3mm, pickling the niobium-titanium chips and putting them into a vacuum annealing furnace, and heating ^them to Vacuum annealing at 900°C and holding for 60 minutes to obtain pretreated niobium-titanium scrap;

Step 2. Part of the pretreated niobium-titanium scrap obtained in step 1 and 0-grade sponge titanium with a particle size of 3mm to 12.7mm were mixed with a mixer for 3 minutes to obtain mixture A, and the remaining pretreated niobium-titanium scrap obtained in step 1 Chips, aluminum-niobium alloy and aluminum-chromium alloy were mixed with a mixer for 5 minutes to obtain mixture B;

Step 3. Divide the mixture A obtained in step 2 into two parts, namely mixture A ₁ and mixture A ₂ . First, pour mixture A ₁ into the pressing mold and spread the cloth to form the lower layer, and then pour mixture B into the pressing mold to spread The flat cloth forms the middle layer, and then the mixture _A2 is poured into the pressing mold to flatten the cloth to form the upper layer, which is pressed by a hydraulic press to obtain 20 electrode blocks with a single weight of 15 kg;

Step 4. Divide the 20 electrode blocks obtained in step 3 into 4 groups, use vacuum welding box copper electrode plasma arc welding for group welding, and use titanium thin plate repair welding at the group welding position, and weld every 5 electrode blocks 1 electrode rod was obtained, and a total of 4 electrode rods were obtained; during the assembly welding process, the electrode blocks were put into the vacuum welding box and placed evenly and symmetrically, and the fixture was adjusted and tightened. When it exceeds 3Pa, test the air leakage rate to ensure that the air leakage rate does not exceed 2.5Pa·min ^-1 , then fill it with argon to a pressure of 45kPa and start welding, and the welding current used is 320A~370A, and the welding voltage is 50V~70V;

Step 5. Place the four electrode rods obtained in step 4 as consumable electrodes in a vacuum consumable electric arc furnace for one smelting. A crucible with a diameter of φ220mm is used for one smelting. The smelting flow is 5kA to 9kA, and the smelting voltage is 29V ~ 32V, melting vacuum degree is 1.0Pa ~ 3.0Pa, get 4 primary ingots, then connect the 4 primary ingots with flat head and tail in sequence and place them in a vacuum consumable electric arc furnace for welding to get 2 ingots electrodes, and carry out secondary melting on the two electrodes. The secondary melting uses a crucible with a diameter of φ280mm, the melting flow is 5kA~10kA, the melting voltage is 29V~33V, and the melting vacuum is 0.5Pa~1.6Pa, and two secondary Ingot casting, then two secondary ingots are connected head to tail and placed in a vacuum consumable arc furnace for assembly welding to obtain an electrode, and one electrode is smelted three times, and a crucible with a diameter of φ360mm is used for the third smelting , the smelting flow is 7kA~12kA, the smelting voltage is 33V~36V, the smelting vacuum is 0.3Pa~0.9Pa, and after cooling for 1h, three ingots are obtained, that is, the niobium titanium aluminum base with the nominal composition of Ti-13Al-32Nb-2Cr alloy ingot.

The niobium-titanium-aluminum-based alloy ingot prepared in this example was flat-headed and skinned, and then the ingot was sawed in the middle and samples were taken from the upper, middle and lower parts of the ingot to detect the chemical composition. The results showed that the niobium-titanium The mass contents of niobium in the upper, middle and lower parts of the aluminum-based alloy ingot are 49.92%, 49.75% and 49.55% respectively, the absolute value of the fluctuation deviation of the composition is less than 1%, and the composition uniformity of each alloy is good. At the same time, after further testing, the niobium-titanium-aluminum-based alloy ingot prepared in this example has no defects such as niobium inclusions, and meets the requirements of large-scale industrial production on the uniformity of alloy composition distribution of the niobium-titanium-aluminum-based alloy ingot.

The above descriptions are only preferred embodiments of the present invention, and do not limit the present invention in any way. All simple modifications, changes and equivalent changes made to the above embodiments according to the technical essence of the invention still belong to the protection scope of the technical solution of the invention.

Claims (5)

1. A preparation method of a niobium-titanium-aluminum-based alloy ingot is characterized by comprising the following steps:

crushing niobium-titanium cast ingots to obtain niobium-titanium fragments, pickling the niobium-titanium fragments, and then carrying out vacuum annealing treatment to obtain pretreated niobium-titanium fragments;

step two, mixing part of the pretreated niobium-titanium scraps obtained in the step one with titanium sponge to obtain a mixture A, and mixing the rest of the pretreated niobium-titanium scraps obtained in the step one with an aluminum-niobium alloy and other intermediate alloys to obtain a mixture B;

step three, distributing the mixture A obtained in the step two as an upper layer and a lower layer and the mixture B as an intermediate layer in a pressing die, and then pressing to obtain an electrode block;

step four, carrying out assembly welding treatment on the electrode block obtained in the step three, and carrying out repair welding on the assembly welding position by adopting a titanium sheet to obtain an electrode rod;

and step five, placing the electrode rod obtained in the step four as a consumable electrode in a vacuum consumable arc furnace for primary smelting to obtain a primary ingot, then sequentially connecting the head and the tail of 4 primary ingots after flatting the head, placing the ingots in the vacuum consumable arc furnace for assembly welding to obtain 2 electrodes, carrying out secondary smelting on the 2 electrodes to obtain 2 secondary ingots, then connecting the head and the tail of 2 secondary ingots after flatting the head, placing the ingots in the vacuum consumable arc furnace for assembly welding to obtain 1 electrode, and carrying out tertiary smelting on the 1 electrode to obtain a tertiary ingot, namely the niobium-titanium-aluminum-based alloy ingot.

2. The method for preparing the niobium-titanium-aluminum-based alloy ingot according to claim 1, wherein the grain size of the niobium-titanium scrap in the first step is 1mm to 3mm, and the vacuum annealing conditions are as follows: vacuum degree less than 5X 10 ^-2 MPa, the temperature is 900-950 ℃, and the time is more than 60 min.

3. The method for preparing the niobium-titanium-aluminum-based alloy ingot according to claim 1, wherein the titanium sponge in the second step is grade 0 titanium sponge with the particle size of 3mm to 12.7mm, the titanium sponge is mixed by a mixer for 3min to obtain a mixture A, and the mixture is mixed by the mixer for 5min to obtain a mixture B.

4. The method of producing an ingot of niobium-titanium-aluminum-based alloy as claimed in claim 1, wherein the mixture A of the upper and lower layers in step three is equal in mass.

5. The method for preparing the niobium-titanium-aluminum-based alloy ingot according to claim 1, wherein the assembly welding treatment in the fourth step is performed by vacuum welding box copper-electrode plasma arc welding.