Preparation method of low-oxygen low-nitrogen nickel-niobium intermediate alloy

Abstract

The invention discloses a preparation method of a low-oxygen low-nitrogen nickel-niobium intermediate alloy, and belongs to the technical field of niobium-based alloy metallurgy. Comprising the following steps that 1, smelting preparation is conducted, specifically, a high-purity nickel raw material and a high-purity niobium raw material are selected, the purity of the nickel raw material is not lower than 99.99%, the purity of the niobium raw material is not lower than 99.9%, the raw materials are pretreated, the raw materials are heated to a certain temperature in a vacuum environment and subjected to heat preservation for a certain time, gas and impurities adsorbed on the surfaces of the raw materials are removed, and smelting is conducted; the nickel raw material is heated to 800-900 DEG C under the condition that the vacuum degree is not lower than 1 * 10 Pa, heat preservation is carried out for 2-3 hours, the niobium raw material is heated to 1000-1100 DEG C under the condition of the same vacuum degree, and heat preservation is carried out for 3-4 hours; according to the method, the content of oxygen and nitrogen in the nickel-niobium intermediate alloy can be effectively reduced, the mechanical property and corrosion resistance of the nickel-niobium intermediate alloy are improved, and the method has high practical value.

Description

Technical Field

[0001] The invention relates to the technical field of niobium-based alloy metallurgy, and in particular to a method for preparing a low-oxygen and low-nitrogen nickel-niobium master alloy. Background Art

[0002] Nickel-niobium master alloys are widely used in modern industry, especially in high-end fields such as aerospace, electronics, etc. In these fields, there are extremely strict requirements for the purity and impurity content of materials. Among them, oxygen and nitrogen, as impurity elements, will seriously affect the performance of nickel-niobium master alloys if their content is too high. Traditional preparation methods often make it difficult to effectively control the content of oxygen and nitrogen, resulting in the performance of the prepared alloys unable to meet the requirements of high-end applications. For example, high oxygen content may form oxide inclusions inside the alloy, reducing the mechanical properties and corrosion resistance of the alloy; high nitrogen content may affect the crystal structure and phase stability of the alloy, thereby affecting its performance under special conditions of high temperature and high pressure. Summary of the invention

[0003] The object of the present invention is to provide a method for preparing a low-oxygen and low-nitrogen nickel-niobium master alloy to solve the problems raised in the above background technology.

[0004] By adopting the above technical solution, the contents of oxygen and nitrogen in the nickel-niobium master alloy can be effectively reduced, and the mechanical properties and corrosion resistance of the nickel-niobium master alloy can be improved.

[0005] In view of the above problems, the technical solution proposed by the present invention is: A method for preparing a low-oxygen and low-nitrogen nickel-niobium master alloy comprises the following steps: Step 1: Smelting preparation: Select high-purity nickel and niobium raw materials, where the purity of the nickel raw material is not less than 99.99%, and the purity of the niobium raw material is not less than 99.9%. Pre-treat the raw materials, heat the raw materials to a certain temperature in a vacuum environment and keep them warm for a certain period of time to remove the gas and impurities adsorbed on the surface of the raw materials. The nickel raw material is heated to 800-900°C under a vacuum degree of not less than 1×10⁻³Pa and kept warm for 2-3 hours. The niobium raw material is heated to 1000-1100°C under the same vacuum degree conditions and kept warm for 3-4 hours. Step 2, smelting: the nickel raw material and niobium raw material in step 1 are placed in a vacuum induction melting furnace at a melting temperature of 1600-1700°C, and high-purity argon gas is introduced into the furnace as a protective gas. The purity of the argon gas is not less than 99.999%, and the flow rate is controlled at 20-30 L / min. During the smelting process, electromagnetic stirring is used to stir the liquid metal at a stirring frequency of 20-30 Hz; Step 3, refining treatment: after the alloy melt is smelted in step 2, add appropriate amounts of deoxidizer and denitrifier to the melt, the amount of deoxidizer added is 0.5% to 1% of the total mass of the alloy, and the amount of denitrifier added is 0.3% to 0.8% of the total mass of the alloy. During the refining process, the temperature is maintained at 1650 to 1750 ° C for 30 to 45 minutes, and high-purity argon is continuously introduced, and the flow rate is adjusted to 15 to 20 L / min; Step 4: Casting: After refining, the alloy melt is injected into a mold preheated to 800-900°C by bottom casting. The casting speed is controlled at 2-3 kg / s. During the casting process, a gas protection cover is set around the mold, and high-purity argon gas is continuously introduced into the protection cover to ensure that the casting environment is in a low-oxygen and low-nitrogen state.

[0006] As a preferred technical solution of the present invention, in step 1, after selecting high-purity nickel raw materials and niobium raw materials, each batch of raw materials is subjected to component analysis and quality inspection to detect the types and contents of trace elements therein, and qualified nickel raw materials and niobium raw materials are screened out.

[0007] Among them, by testing the nickel raw materials and niobium raw materials, it is ensured that the purity of the nickel raw materials is not less than 99.99%, and the purity of the niobium raw materials is not less than 99.9%. The types and contents of trace elements inside them are also tested to ensure that the detected trace elements and contents will not affect the performance of the alloy.

[0008] As a preferred technical solution of the present invention, the qualified nickel raw material and niobium raw material are cut, cleaned and dried.

[0009] Among them, when cutting the nickel raw materials and niobium raw materials that have passed the inspection, special cutting equipment is needed to avoid introducing new impurities. The nickel raw materials and niobium raw materials are cleaned with ethanol with a purity higher than 99.9% to remove oil and dust on the surface. After cleaning, they are placed in a drying oven for drying at a drying temperature of 80 to 120°C and a drying time of 2 to 4 hours.

[0010] As a preferred technical solution of the present invention, in step 2, part of the nickel raw material is evenly laid on the furnace bottom to form a bottom layer, and then the niobium raw material is evenly distributed on the nickel raw material, and finally the remaining nickel raw material is laid on the upper end of the niobium raw material.

[0011] Among them, the nickel raw material is first melted in the bottom layer to form a molten pool to wrap the niobium raw material and promote the alloy reaction.

[0012] As a preferred technical solution of the present invention, in step three, the deoxidizer is a calcium silicon alloy, and the denitrifier is a titanium aluminum zirconium alloy.

[0013] Among them, calcium silicon alloy is in a vacuum degree of 5×10⁻ 4Pa and kept warm for 1 to 2 hours. The titanium aluminum zirconium alloy was heated to 600 to 700°C under the same vacuum degree and kept warm for 1.5 to 2.5 hours. The calcium silicon alloy and the titanium aluminum zirconium alloy were heated to a certain temperature in a vacuum environment and kept warm for a period of time to remove the gas adsorbed on the surface and the possible low melting point impurities.

[0014] As a preferred technical solution of the present invention, in step three, a ceramic skimming tool is regularly used to remove scum generated on the surface of the melt.

[0015] Among them, slag is an impurity product generated by the reaction with deoxidizer and denitrifier during the refining process.

[0016] As a preferred technical solution of the present invention, in step four, the inner surface of the mold is coated with a high-temperature anti-stick coating.

[0017] Among them, the high-temperature anti-stick coating is a mixture of high-temperature resistant ceramic materials and organic binders. The mold is first sandblasted to increase the surface roughness, and then the coating material is evenly sprayed on the inner surface of the mold and dried and cured at 200-300°C.

[0018] Compared with the prior art, the invention has the following beneficial effects: the preparation method of the low-oxygen and low-nitrogen nickel-niobium intermediate alloy can ensure that no additional impurities that affect the alloy performance are introduced by detecting the types and contents of trace elements in the nickel raw material and the niobium raw material, so that users can be convenient to screen the raw materials; by cutting the large blocks of nickel raw material and niobium raw material that have passed the inspection into suitable sizes, subsequent pretreatment and smelting operations are convenient; by carrying out the cutting process in a clean environment and using special cutting equipment, the introduction of new impurities can be avoided; by washing the cut raw materials with ethanol, oil and dust on the surface thereof can be removed; by first laying a part of the nickel raw material, then laying the niobium raw material, and finally laying the remaining part of the nickel raw material, it is beneficial for the nickel to melt first to form a molten pool in the early stage of smelting, so as to better wrap the niobium raw material and promote the alloying reaction; by setting the titanium-aluminum-zirconium alloy, the three metals of titanium, aluminum and zirconium have a strong affinity for nitrogen in a high-temperature melt environment. They can react with nitrogen atoms in the alloy melt to form stable nitrides, thereby achieving the purpose of denitrification. By coating with a high-temperature anti-stick coating, the alloy melt can be prevented from sticking to the mold, ensuring the surface quality of the alloy after casting, and also facilitating demolding operations. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] Figure 1 This is a block diagram of a method for preparing a low-oxygen and low-nitrogen nickel-niobium master alloy disclosed in an embodiment of the present invention. DETAILED DESCRIPTION

[0020] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0021] For example, see Figure 1 The present invention provides a technical solution: a method for preparing a low-oxygen and low-nitrogen nickel-niobium master alloy, comprising the following steps: Step 1: Smelting preparation: Select high-purity nickel and niobium raw materials, where the purity of the nickel raw material is not less than 99.99%, and the purity of the niobium raw material is not less than 99.9%. Pre-treat the raw materials, heat the raw materials to a certain temperature in a vacuum environment and keep them warm for a certain period of time to remove the gas and impurities adsorbed on the surface of the raw materials. The nickel raw material is heated to 800-900°C under a vacuum degree of not less than 1×10⁻³Pa and kept warm for 2-3 hours. The niobium raw material is heated to 1000-1100°C under the same vacuum degree conditions and kept warm for 3-4 hours. Step 2, smelting: the nickel raw material and niobium raw material in step 1 are placed in a vacuum induction melting furnace at a melting temperature of 1600-1700°C, and high-purity argon gas is introduced into the furnace as a protective gas. The purity of the argon gas is not less than 99.999%, and the flow rate is controlled at 20-30 L / min. During the smelting process, electromagnetic stirring is used to stir the liquid metal at a stirring frequency of 20-30 Hz; Step 3, refining treatment: after the alloy melt is smelted in step 2, add appropriate amounts of deoxidizer and denitrifier to the melt, the amount of deoxidizer added is 0.5% to 1% of the total mass of the alloy, and the amount of denitrifier added is 0.3% to 0.8% of the total mass of the alloy. During the refining process, the temperature is maintained at 1650 to 1750 ° C for 30 to 45 minutes, and high-purity argon is continuously introduced, and the flow rate is adjusted to 15 to 20 L / min; Step 4: Casting: After refining, the alloy melt is injected into a mold preheated to 800-900°C by bottom casting. The casting speed is controlled at 2-3 kg / s. During the casting process, a gas protection cover is set around the mold, and high-purity argon gas is continuously introduced into the protection cover to ensure that the casting environment is in a low-oxygen and low-nitrogen state.

[0022] In one embodiment of the present invention, after selecting high-purity nickel raw materials and niobium raw materials in step one, component analysis and quality inspection are performed on each batch of raw materials to detect the types and contents of trace elements therein, and qualified nickel raw materials and niobium raw materials are screened out. By detecting the types and contents of trace elements in the nickel raw materials and niobium raw materials, it can be ensured that no additional impurities that affect the properties of the alloy are introduced, so that users can conveniently screen the raw materials.

[0023] According to an embodiment of the present invention, the qualified nickel raw materials and niobium raw materials are further cut, cleaned and dried. By cutting the qualified bulk nickel raw materials and niobium raw materials into suitable sizes, subsequent pretreatment and smelting operations are facilitated. By carrying out the cutting process in a clean environment and using special cutting equipment, the introduction of new impurities can be avoided. By cleaning the cut raw materials with ethanol, oil and dust on their surfaces can be removed.

[0024] According to an embodiment of the present invention, further, in step 2, part of the nickel raw material is first evenly laid on the bottom of the furnace to form a bottom layer, and then the niobium raw material is evenly distributed on the nickel raw material, and finally the remaining nickel raw material is laid on the upper end of the niobium raw material. By first laying part of the nickel raw material, then laying the niobium raw material, and finally laying the remaining part of the nickel raw material, it is beneficial for the nickel to melt first to form a molten pool in the early stage of smelting, so as to better wrap the niobium raw material and promote the alloying reaction.

[0025] In one embodiment of the present invention, further, in step 3, the deoxidizer is a calcium silicon alloy, and the denitrifier is a titanium aluminum zirconium alloy. By setting the calcium silicon alloy, when the calcium silicon alloy is added to the high-temperature alloy melt, calcium and silicon will chemically react with the oxygen in the alloy, so that the oxygen in the alloy is fixed in the form of oxides, thereby achieving the purpose of deoxidation. By setting the titanium aluminum zirconium alloy, the three metals of titanium, aluminum, and zirconium have a strong affinity for nitrogen in a high-temperature melt environment. They can react with nitrogen atoms in the alloy melt to form stable nitrides, thereby achieving the purpose of denitrification.

[0026] According to an embodiment of the present invention, further, in step three, a ceramic skimming tool is regularly used to remove scum generated on the surface of the melt.

[0027] According to an embodiment of the present invention, further, in step four, the inner surface of the mold is coated with a high-temperature anti-stick coating. By coating the high-temperature anti-stick coating, the alloy melt can be prevented from sticking to the mold, thereby ensuring the surface quality of the alloy after casting and facilitating the demolding operation.

[0028] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0029] Example 2, raw material preparation: select a nickel raw material with a purity of 99.992% and a niobium raw material with a purity of 99.93%, use a spectrometer to conduct a comprehensive test on the raw materials to ensure that in addition to the main components meet the requirements, the content of other trace elements is at an extremely low level, for the nickel raw material, the iron content is controlled below 5ppm, the carbon content is below 3ppm, and the sulfur content is below 2ppm, for the niobium raw material, the iron content is controlled below 8ppm, the carbon content is below 5ppm, and the sulfur content is below 3ppm, the raw material cutting and cleaning, the nickel raw material is cut into cubes with a side length of 5-8cm, and the niobium raw material is cut into cylinders with a diameter of 3-6cm and a height of 5-10cm. The cut raw materials are ultrasonically cleaned in ethanol with a purity of 99.95% for 30 minutes, and then dried in a vacuum drying oven at 100°C for 3 hours.

[0030] Melting process: first lay a 3cm thick layer of nickel raw material on the bottom of the vacuum induction melting furnace, then evenly place the niobium raw material cylinders on the nickel layer, with a spacing of 2 to 3cm between each cylinder, and finally cover it with a 4cm thick layer of nickel raw material. The loading process is carried out in a clean room protected by high-purity argon gas. The oxygen content in the clean room is controlled below 1ppm and the humidity is less than 1%. At the beginning of smelting, the smelting furnace is started with a power of 50kW, and the temperature is raised at a rate of 10℃ / min. When the temperature reaches 1200℃, the power is adjusted to 80kW and the temperature continues to rise. When the temperature approaches 1600℃, the power is fine-tuned between 100 and 110kW according to temperature feedback to maintain the melting temperature at 1620℃. At the same time, argon gas with a purity of 99.9995% is introduced at a flow rate of 22L / min.

[0031] Refining treatment: Calcium silicon alloy is placed in a vacuum of 3×10⁻ 4 Pa and kept warm for 1.5 hours. The titanium aluminum zirconium alloy was heated to 650°C under the same vacuum degree and kept warm for 2 hours. The pretreated calcium silicon alloy and titanium aluminum zirconium alloy were stored in a sealed container filled with high-purity argon before use. During the refining process, the temperature was maintained at 1680°C for 35 minutes. Electromagnetic stirring was adopted with a frequency of 22 Hz. A ceramic skimmer was used to remove the scum on the surface of the melt every 10 minutes.

[0032] Casting: The mold is preheated to 850°C, and a coating material composed of 70% boron nitride and 30% silicone binder is used. The mold is sandblasted to a surface roughness Ra of 6-8μm, and then the coating material is evenly sprayed with a coating thickness of 0.2-0.3mm. It is dried and cured at 250°C for 2 hours. The liquid level is monitored in real time by a high-precision liquid level sensor. When the liquid level reaches 80% of the mold height, the casting speed is adjusted from 2.2kg / s to 1.8kg / s. After casting, an insulating riser is set on the top of the mold, and the riser is filled with a heating covering agent. The heating temperature can reach 1200°C and lasts for 30 minutes, providing good shrinkage compensation conditions for the alloy melt.

[0033] After testing, the obtained nickel-niobium master alloy had an oxygen content of 38 ppm and a nitrogen content of 22 ppm.

[0034] Example 3, raw material preparation: A nickel raw material with a purity of 99.998% and a niobium raw material with a purity of 99.95% were selected, and the raw materials were deeply analyzed by inductively coupled plasma mass spectrometry to ensure that the total amount of impurity elements in the nickel raw material did not exceed 20 ppm, and the total amount of impurity elements in the niobium raw material did not exceed 50 ppm. For key impurities that may affect the properties of the alloy, the phosphorus content in the nickel raw material was controlled to be below 1 ppm, and the boron content was below 0.5 ppm. The phosphorus content in the niobium raw material was controlled to be below 2 ppm, and the boron content was below 1 ppm. The nickel raw material was cut into a plate with a thickness of 3 to 5 cm, and the niobium raw material was cut into a cube with a side length of 4 to 6 cm. The cut raw materials were washed twice with ethanol with a purity of 99.98%, soaked for 20 minutes each time, and then dried in a vacuum drying oven at 90° C. for 2.5 hours.

[0035] Melting process: a 2.5cm thick nickel plate is laid flat on the bottom of the vacuum induction melting furnace, and then niobium cubes are placed on the nickel plate in a staggered manner to form two layers of niobium raw material layers. There is a gap of 1 to 2cm between each layer of niobium cubes, and finally covered with a 3.5cm thick nickel plate. The loading process is carried out in a clean room protected by high-purity argon gas. The purity of argon gas in the clean room is 99.999%, and the oxygen content is less than 0.5ppm. The melting furnace is started, and the initial power is set to 40kW. The temperature is raised to 1100℃ at a rate of 8℃ / min, and then the power is adjusted to 70kW, and the temperature continues to rise. When the temperature approaches 1650℃, the power is controlled at 90-100kW to stabilize the melting temperature at 1680℃. At the same time, argon gas with a purity of 99.9998% is introduced at a flow rate of 28L / min.

[0036] Refining treatment: Calcium silicon alloy is heated to 2×10⁻ 4Pa and kept warm for 1.8 hours. The titanium aluminum zirconium alloy was heated to 680°C under the same vacuum degree and kept warm for 2.2 hours. The treated additives were transferred to the melting furnace feeding device under argon protection. During refining, the temperature was maintained at 1720°C for 40 minutes. Electromagnetic stirring was adopted with a frequency of 28 Hz. The slag skimming operation was performed every 8 minutes. The surface of the ceramic slag skimming tool was coated with a layer of graphite to reduce contamination of the melt.

[0037] Casting: The mold is preheated to 880°C, and the coating material is 80% yttria-stabilized zirconium oxide and 20% organic zirconate binder. After the mold is polished, the surface roughness Ra reaches 5-7μm. The coating material is evenly sprayed, and the coating thickness is about 0.25mm. It is dried and cured at 280°C for 1.5 hours. Using the liquid level sensor and automatic control system, when the liquid level reaches 75% of the mold height, the casting speed begins to be linearly reduced from 2.8kg / s to 2.0kg / s. After the casting is completed, the pressure-feeding method is used to apply a pressure of 0.3MPa to the mold through an external pressure device for 5 minutes to ensure the density of the alloy ingot.

[0038] After testing, the obtained nickel-niobium master alloy had an oxygen content of 32 ppm and a nitrogen content of 18 ppm.

[0039] Example 4, raw material preparation: select a nickel raw material with a purity of 99.996% and a niobium raw material with a purity of 99.94%, use atomic absorption spectroscopy and X-ray fluorescence spectroscopy to detect the raw materials, ensure that the copper content in the nickel raw material is less than 3ppm, the manganese content is less than 2ppm, the copper content in the niobium raw material is less than 5ppm, and the manganese content is less than 3ppm. At the same time, confirm again that the purity of the main components meets the requirements, cut the nickel raw material into strips with a length of 10 to 15cm, a width of 3 to 5cm, and a thickness of 2 to 3cm, and cut the niobium raw material into strips of similar size. The cut raw materials are soaked and cleaned in ethanol for 35 minutes, and then dried in a vacuum drying oven at 110°C for 3.5 hours.

[0040] Melting process: First place a layer of nickel strips at the bottom of the vacuum induction melting furnace to form a bottom layer with a thickness of about 3cm, then arrange the niobium strips on the nickel layer in a crisscross manner, and then cover it with a layer of nickel strips with a thickness of about 3.5cm. The loading process is carried out in a clean room protected by high-purity argon gas. The purity of the argon gas in the clean room is 99.9992%, the oxygen content is less than 0.3ppm, and the humidity is less than 0.5%. When the melting begins, it starts with a power of 45kW, and the temperature rises to 1150℃ at a rate of 9℃ / minute. Then increase the power to 75kW and continue to heat up. When it approaches 1680℃, stabilize the power at 95-105kW, keep the melting temperature at 1690℃, and introduce argon gas with a purity of 99.9996% at a flow rate of 26L / min.

[0041] Refining treatment: Calcium silicon alloy is heated to 4×10⁻ 4 Pa and kept warm for 1.2 hours. The titanium aluminum zirconium alloy was heated to 620°C under the same vacuum degree and kept warm for 1.8 hours. The pretreated additives were stored in a sealed container in an argon atmosphere and briefly preheated to 200-300°C before being added to the melt. In the refining stage, the temperature was maintained at 1700°C for 38 minutes. Electromagnetic stirring was used with a frequency of 25Hz to ensure uniform stirring of the melt. A ceramic skimmer was used for slag removal every 12 minutes to remove the scum on the surface of the melt.

[0042] Casting: The mold is preheated to 820°C, and a composite coating consisting of 60% boron nitride, 30% yttria-stabilized zirconia and 10% organosilane binder is used. The mold is pretreated and the surface roughness Ra is 7-9μm. The coating is evenly sprayed on the inner surface of the mold with a coating thickness of 0.22mm. It is dried and cured at 220°C for 2.5 hours. The casting process is controlled in real time by a high-precision liquid level monitoring system. When the liquid level reaches 82% of the mold height, the casting speed is adjusted from 2.5kg / s to 2.1kg / s. After casting, a heat-insulating riser and a pressurized shrinkage-feeding combination are set on the top of the mold. The heat-insulating riser is filled with high-efficiency heating and insulation materials, which can raise the temperature to above 1000°C within 10 minutes. At the same time, an external pressure device applies a pressure of 0.4MPa for 3 minutes to reduce shrinkage defects.

[0043] After testing, the obtained nickel-niobium master alloy had an oxygen content of 35 ppm and a nitrogen content of 20 ppm.

Claims

1. A method for preparing a low-oxygen and low-nitrogen nickel-niobium master alloy, characterized in that: The following steps are involved: Step 1: Smelting preparation: Select high-purity nickel and niobium raw materials, where the purity of the nickel raw material is not less than 99.99%, and the purity of the niobium raw material is not less than 99.9%. Pre-treat the raw materials, heat the raw materials to a certain temperature in a vacuum environment and keep them warm for a certain period of time to remove the gas and impurities adsorbed on the surface of the raw materials. The nickel raw material is heated to 800-900°C under a vacuum degree of not less than 1×10⁻³Pa and kept warm for 2-3 hours. The niobium raw material is heated to 1000-1100°C under the same vacuum degree conditions and kept warm for 3-4 hours. Step 2, smelting: the nickel raw material and niobium raw material in step 1 are placed in a vacuum induction melting furnace at a melting temperature of 1600-1700°C, and high-purity argon gas is introduced into the furnace as a protective gas. The purity of the argon gas is not less than 99.999%, and the flow rate is controlled at 20-30 L / min. During the smelting process, electromagnetic stirring is used to stir the liquid metal at a stirring frequency of 20-30 Hz; Step 3, refining treatment: after the alloy melt is smelted in step 2, add appropriate amounts of deoxidizer and denitrifier to the melt, the amount of deoxidizer added is 0.5% to 1% of the total mass of the alloy, and the amount of denitrifier added is 0.3% to 0.8% of the total mass of the alloy. During the refining process, the temperature is maintained at 1650 to 1750 ° C for 30 to 45 minutes, and high-purity argon is continuously introduced, and the flow rate is adjusted to 15 to 20 L / min; Step 4: Casting: After refining, the alloy melt is injected into a mold preheated to 800-900°C by bottom casting. The casting speed is controlled at 2-3 kg / s. During the casting process, a gas protection cover is set around the mold, and high-purity argon gas is continuously introduced into the protection cover to ensure that the casting environment is in a low-oxygen and low-nitrogen state.

2. The method for preparing a low-oxygen and low-nitrogen nickel-niobium master alloy according to claim 1, characterized in that: In the step 1, after selecting high-purity nickel raw materials and niobium raw materials, each batch of raw materials is subjected to component analysis and quality inspection to detect the types and contents of trace elements therein, and qualified nickel raw materials and niobium raw materials are screened out.

3. The method for preparing a low-oxygen and low-nitrogen nickel-niobium master alloy according to claim 2, characterized in that: The qualified nickel raw material and niobium raw material are cut, cleaned and dried.

4. The method for preparing a low-oxygen and low-nitrogen nickel-niobium master alloy according to claim 1, characterized in that: In the step 2, part of the nickel raw material is evenly laid on the furnace bottom to form a bottom layer, and then the niobium raw material is evenly distributed on the nickel raw material, and finally the remaining nickel raw material is laid on the upper end of the niobium raw material.

5. The method for preparing a low-oxygen and low-nitrogen nickel-niobium master alloy according to claim 1, characterized in that: In the step three, the deoxidizer is a calcium silicon alloy, and the denitrifier is a titanium aluminum zirconium alloy.

6. The method for preparing a low-oxygen and low-nitrogen nickel-niobium master alloy according to claim 1, characterized in that: In the step 3, a ceramic skimming tool is used regularly to remove scum generated on the surface of the melt.

7. The method for preparing a low-oxygen and low-nitrogen nickel-niobium master alloy according to claim 1, characterized in that: In the step 4, the inner surface of the mold is coated with a high-temperature anti-stick coating.

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