Low-oxygen low-nitrogen aluminum-niobium intermediate alloy and preparation method thereof

Abstract

The invention provides a low-oxygen low-nitrogen aluminum-niobium intermediate alloy and a preparation method thereof, and belongs to the technical field of intermediate alloys. The preparation method of the low-oxygen low-nitrogen aluminum-niobium intermediate alloy comprises the following steps that a niobium source, an aluminum source and an oxidizing agent are mixed, then charging is conducted under the argon and vibration conditions, and a mixture is obtained; and the mixture is sequentially subjected to a thermit reaction and cooling under the vibration condition, and the low-oxygen low-nitrogen aluminum-niobium intermediate alloy is obtained. According to the method, charging is carried out under the argon and vibration conditions, air remaining in gaps of mixture particles can be eliminated, introduction of oxygen and nitrogen in the thermit reaction process is reduced, and therefore the oxygen and nitrogen content of the aluminum-niobium intermediate alloy is reduced; and the thermit reaction and cooling are carried out under the vibration condition, so that thick dendritic crystals formed in the alloy solidification process can be crushed, the purpose of grain refinement is achieved, fine grain strengthening is achieved, and the obdurability of the aluminum-niobium intermediate alloy is improved.

Description

Technical Field

[0001] The present invention belongs to the technical field of master alloys, and in particular relates to a low-oxygen and low-nitrogen aluminum-niobium master alloy and a preparation method thereof. Background Art

[0002] Aluminum-niobium alloy is a refractory master alloy formed by refractory metal niobium and metal aluminum. It has a high melting point, low density, good high-temperature strength and excellent creep resistance. It is mainly used in aerospace, shipbuilding and ocean industries.

[0003] Due to the high melting point of aluminum-niobium alloys, they are typically prepared using the aluminothermic method. However, since the raw materials used are granular or powdered, air trapped between the raw material particles results in high oxygen and nitrogen content in the alloy ingots. Furthermore, oxygen and nitrogen can cause colored oxide or nitride films to form within the alloy ingots, leading to cracking and poor toughness of the aluminum-niobium alloy. Therefore, improving the preparation method to reduce the oxygen and nitrogen content and improve toughness in aluminum-niobium master alloys has become a pressing technical challenge in this field. Summary of the Invention

[0004] The present invention aims to provide a low-oxygen and low-nitrogen aluminum-niobium master alloy and a preparation method thereof. The aluminum-niobium master alloy prepared by the preparation method provided by the present invention is low in oxygen and nitrogen and has excellent strength and toughness.

[0005] In order to achieve the above-mentioned object of the invention, the present invention provides the following technical solutions:

[0006] The present invention provides a method for preparing a low-oxygen and low-nitrogen aluminum-niobium master alloy, comprising the following steps:

[0007] (1) mixing a niobium source, an aluminum source, and an oxidant, and then charging the mixture under argon gas and vibration conditions to obtain a mixture;

[0008] (2) subjecting the mixture obtained in step (1) to a thermite reaction and cooling in sequence under vibration conditions to obtain a low-oxygen and low-nitrogen aluminum-niobium master alloy.

[0009] Preferably, the D of the niobium source and the aluminum source in step (1) 50 Independently 1 to 2 mm.

[0010] Preferably, in step (1), the mass ratio of the niobium source, the aluminum source and the oxidant is (5-5.5): (4.5-5): (1-1.2).

[0011] Preferably, the argon gas in step (1) is bottom-blown argon gas; the flow rate of the argon gas is 7 to 12 L / min.

[0012] Preferably, the frequencies of the vibration in step (1) and the vibration in step (2) are independently 150 to 200 Hz.

[0013] Preferably, in step (1), the material is added to the molten pool in batches, and the height of each batch of material added to the molten pool is not greater than 15 cm.

[0014] Preferably, the time for introducing argon gas after the first batch of materials are added to the molten pool is 3 to 5 minutes, the time for introducing argon gas after the second batch of materials are added to the molten pool is 6 to 10 minutes, and the time for introducing argon gas after the third batch of materials are added to the molten pool is 12 to 20 minutes. As the number of batches increases, the time for introducing argon gas increases exponentially until the loading is completed.

[0015] Preferably, the molten pool is made of magnesia bricks, and the material of the bottom of the molten pool is porous magnesia bricks, the pore size of the porous magnesia bricks is ≤0.1 mm, and the thickness of the porous magnesia bricks is ≥10 cm.

[0016] Preferably, the molten pool is placed on a vibration platform, an opening is provided at the center of the vibration platform, and the argon passing device is connected to the molten pool through the opening.

[0017] The present invention also provides a low-oxygen and low-nitrogen aluminum-niobium master alloy prepared by the preparation method described in the above technical solution, wherein the oxygen content of the low-oxygen and low-nitrogen aluminum-niobium master alloy is ≤0.012wt%, and the nitrogen content is ≤0.013wt%.

[0018] The present invention provides a method for preparing a low-oxygen, low-nitrogen aluminum-niobium master alloy, comprising the following steps: mixing a niobium source, an aluminum source, and an oxidant, then charging the mixture under argon and vibration conditions to obtain a mixture; and sequentially subjecting the mixture to a thermite reaction and cooling under vibration conditions to obtain a low-oxygen, low-nitrogen aluminum-niobium master alloy. The charging process under argon and vibration conditions removes air trapped between particles in the mixture, reduces the introduction of oxygen and nitrogen during the thermite reaction, and thus reduces the oxygen and nitrogen content of the aluminum-niobium master alloy. The thermite reaction and cooling process under vibration conditions facilitates the breakdown of coarse dendrites formed during solidification, achieving grain refinement and grain strengthening, thereby increasing the strength and toughness of the aluminum-niobium master alloy. Experimental results show that the aluminum-niobium master alloy prepared by the preparation method has an oxygen content of ≤0.012 wt%, a nitrogen content of ≤0.013 wt%, a yield strength of 346.3 to 368.3 MPa, a tensile strength of 486.7 to 526.3 MPa, and an elongation of 8.2 to 8.9%. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] Figure 1 This is a schematic diagram of the structure of the molten pool used in the embodiment. In the figure, 1 is the furnace hood, 2 is the porous magnesia brick, 3 is the vibration platform, 4 is the magnesia brick, 5 is magnesia sand, 6 is the motor, 7 is the regulating coil bracket, 8 is the gas flow regulating valve, and 9 is the magnesia brick. DETAILED DESCRIPTION

[0020] The present invention provides a method for preparing a low-oxygen and low-nitrogen aluminum-niobium master alloy, comprising the following steps:

[0021] (1) mixing a niobium source, an aluminum source, and an oxidant, and then charging the mixture under argon gas and vibration conditions to obtain a mixture;

[0022] (2) subjecting the mixture obtained in step (1) to a thermite reaction and cooling in sequence under vibration conditions to obtain a low-oxygen and low-nitrogen aluminum-niobium master alloy.

[0023] The present invention has no particular limitation on the sources of the raw materials, and commercially available products known to those skilled in the art may be used.

[0024] The present invention mixes a niobium source, an aluminum source and an oxidant, and then charges the mixture under argon gas and vibration conditions to obtain a mixed material.

[0025] In the present invention, the niobium source is preferably niobium pentoxide; the D of the niobium source is 50 Preferably, the thickness of the niobium source is 1 to 2 mm; the purity of the niobium source is preferably ≥ 99.95%. As an embodiment, the D 50 The thickness may be 1 mm, 1.3 mm, 1.5 mm or 1.8 mm; the purity of the niobium source may be 99.95%, 99.96%, 99.97%, 99.98% or 99.99%.

[0026] In the present invention, the aluminum source is preferably aluminum particles; the D of the aluminum source is 50 Preferably, the aluminum source has a purity of ≥99.95%. 50 It can be 1 mm, 1.3 mm, 1.5 mm or 1.8 mm; the purity of the aluminum source can be 99.95%, 99.96%, 99.97%, 99.98% or 99.99%.

[0027] In the present invention, the oxidant is preferably potassium chlorate. In the present invention, the potassium chlorate provides heat for the smelting process by reacting with aluminum particles, making the reaction more thorough.

[0028] In the present invention, the mass ratio of the niobium source, the aluminum source, and the oxidant is preferably (5-5.5): (4.5-5): (1-1.2). As an embodiment, the mass ratio of the niobium source, the aluminum source, and the oxidant can be (5.22-5.24): (4.71-4.74): (1-1.1).

[0029] In the present invention, the niobium source, aluminum source and oxidant are preferably dried before use. The present invention has no particular limitation on the drying operation, and drying to a constant weight is sufficient.

[0030] The present invention has no special limitation on the operation of mixing the niobium source, the aluminum source and the oxidant, and the technical scheme for preparing the mixed material well known to those skilled in the art can be adopted.

[0031] As an embodiment, the niobium source, the aluminum source and the oxidant may be mixed manually; the number of manual mixing is not less than 6 times.

[0032] In the present invention, the argon gas is preferably bottom-blown argon gas; the argon gas flow rate is preferably 7 to 12 L / min. In one embodiment, the argon gas flow rate can be 8 L / min, 9 L / min, 10 L / min, or 11 L / min. Limiting the argon gas flow rate to the aforementioned range can further reduce the oxygen and nitrogen content of the aluminum-niobium master alloy.

[0033] In the present invention, the vibration frequency is preferably 150-200 Hz. As an embodiment, the vibration frequency can be 160 Hz, 170 Hz, 180 Hz, or 190 Hz. Limiting the vibration frequency to the above range can further reduce the oxygen and nitrogen content of the aluminum-niobium master alloy.

[0034] In the present invention, the charge is preferably added to the molten pool in batches, and the height of each batch of material added to the molten pool is preferably no more than 15 cm. As an embodiment, the height of each batch of material added to the molten pool can be 5 cm or 10 cm.

[0035] The present invention has no special limitation on the number of times of batching, which can be selected according to the actual material required, as long as the height of each batch of materials added to the molten pool is no more than 15 cm.

[0036] In the present invention, the time for introducing argon gas after the first batch of materials is added to the molten pool is preferably 3 to 5 minutes, the time for introducing argon gas after the second batch of materials is added to the molten pool is preferably 6 to 10 minutes, and the time for introducing argon gas after the third batch of materials is added to the molten pool is preferably 12 to 20 minutes. As the number of batches increases, the time for introducing argon gas is doubled until the loading is completed. In the present invention, introducing argon gas after adding materials in batches can make the materials more fully purified and avoid the materials being too thick, which makes it difficult for argon gas to flow and leads to poor purification effect.

[0037] In the present invention, the molten pool is preferably constructed of magnesia bricks; the bottom of the molten pool is preferably constructed of porous magnesia bricks; the pore size of the porous magnesia bricks is preferably ≤0.1 mm; and the thickness of the porous magnesia bricks is preferably ≥10 cm. In the present invention, limiting the pore size of the porous magnesia bricks to the aforementioned range ensures that argon gas continuously and stably enters the molten pool to purify the material and prevents leakage of raw materials from the molten pool.

[0038] The structural diagram of the molten pool provided by the present invention is as follows Figure 1 shown.

[0039] like Figure 1 As shown, the molten pool is placed on a vibration platform; an opening is provided at the center of the vibration platform, and the argon passing device is connected to the molten pool through the opening.

[0040] like Figure 1 As shown, the argon transmission device includes an argon gas transmission pipeline; the argon gas transmission pipeline is arranged at the opening; the argon gas transmission pipeline is fixed by an adjusting coil bracket; the argon gas transmission pipeline is provided with a gas flow regulating valve near the opening; the gas flow regulating valve is connected to the argon gas nozzle; the argon gas nozzle is tightly connected to the porous magnesia brick.

[0041] like Figure 1 As shown, a furnace hood is provided outside the molten pool.

[0042] In one embodiment of the present invention, the furnace hood and the molten pool are sealed with magnesia sand to isolate the air.

[0043] like Figure 1 As shown, a triangular magnesia brick is provided on the upper portion of the molten pool. In the present invention, the triangular magnesia brick can make the alloy liquid generated by thermite reaction flow smoothly into the molten pool.

[0044] The present invention can further reduce the oxygen and nitrogen content of the aluminum-niobium master alloy and improve the strength and toughness of the aluminum-niobium master alloy by arranging the structure of the molten pool.

[0045] In the present invention, the vibration platform is preferably a lost foam casting vibration platform; the excitation force of the vibration platform is preferably 70 to 80 kN. As an embodiment, the excitation force of the vibration platform can be 72 kN, 74 kN, 75 kN, 76 kN or 78 kN.

[0046] The present invention has no special limitation on the specific size of the vibration platform, which can be adjusted according to actual needs.

[0047] As an embodiment, the size of the vibration platform may be 1.5m*1.5m; the load capacity of the vibration platform may be ≥2 tons.

[0048] After obtaining the mixture, the present invention sequentially conducts a thermite reaction and cooling under vibration conditions to produce a low-oxygen, low-nitrogen aluminum-niobium master alloy. Continuous vibration during the thermite reaction and cooling promotes rapid escape of gases from the furnace, reduces porosity defects within the alloy ingot, and lowers the gas impurity content of the alloy ingot. It also breaks up coarse columnar crystals formed at the edge of the molten pool due to excessively rapid cooling, forming scattered crystal nuclei, promoting the formation of equiaxed crystals, and improving the strength and toughness of the aluminum-niobium master alloy ingot.

[0049] In the present invention, the vibration frequency is preferably 150-200 Hz. As an embodiment, the vibration frequency can be 160 Hz, 170 Hz, 180 Hz, or 190 Hz. Limiting the vibration frequency to the above range can further improve the toughness of the aluminum-niobium master alloy.

[0050] In the present invention, the temperature of the thermite reaction is preferably 2050-2550° C. As an embodiment, the temperature of the thermite reaction can be 2100° C., 2150° C., 2200° C., 2300° C., or 2500° C. The present invention does not specifically limit the time of the thermite reaction and can be adjusted according to actual needs.

[0051] As an embodiment, the thermite reaction time may be 50s, 55s or 60s.

[0052] In the present invention, the thermite reaction is preferably ignited by a magnesium rod. The present invention has no particular limitation on the operation of igniting the thermite reaction by a magnesium rod, and any operation well known to those skilled in the art can be used.

[0053] The present invention has no special limitation on the cooling operation, and any cooling method well known to those skilled in the art may be used.

[0054] The present invention performs charging under argon and vibration conditions, which can eliminate air remaining in the gaps between the mixed material particles, reduce the introduction of oxygen and nitrogen during the thermite reaction, and thus reduce the oxygen and nitrogen content of the aluminum-niobium master alloy. Performing the thermite reaction and cooling under vibration conditions helps to break up coarse dendrites formed during the solidification process of the alloy, achieves the purpose of grain refinement, realizes fine grain strengthening, and thus improves the strength and toughness of the aluminum-niobium master alloy.

[0055] Compared with the vacuum aluminothermic method, the present invention prepares a low-oxygen and low-nitrogen aluminum-niobium master alloy through an off-furnace aluminothermic method, which has simple procedures, low equipment investment, and a wide range of applications. During the charging process, argon treatment is performed to remove air remaining in the gaps between raw material particles, significantly reducing the oxygen and nitrogen impurity content inside the alloy ingot, and obtaining a higher-purity aluminum-niobium master alloy ingot. During the charging and aluminothermic reaction, vibration treatment is performed to fully remove air remaining in the gaps between raw material particles and reduce the oxygen and nitrogen content in the material. Coarse dendrites formed due to an excessively fast cooling rate are broken, the grains are refined, and the strength and toughness of the aluminum-niobium master alloy are improved.

[0056] The aluminum-niobium master alloy prepared by the method of the present invention has low oxygen and nitrogen impurity contents, and the alloy ingots discharged from the furnace are relatively complete without the presence of colored films. The strength and toughness of the alloy are improved, and the alloy has great industrial value.

[0057] The present invention also provides a low-oxygen and low-nitrogen aluminum-niobium master alloy prepared by the preparation method described in the above technical solution, wherein the oxygen content of the low-oxygen and low-nitrogen aluminum-niobium master alloy is ≤0.012wt%, and the nitrogen content is ≤0.013wt%.

[0058] The following will be combined with the embodiments of the present invention to clearly and completely describe the technical solutions of the present invention. Obviously, the embodiments described are only some of the embodiments of the present invention, not all of them. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of the present invention.

[0059] The structural diagram of the molten pool used in the embodiment is as follows Figure 1 As shown in the figure, 1 is a furnace cover, 2 is a porous magnesia brick, 3 is a vibration platform, 4 is a magnesia brick, 5 is magnesia sand, 6 is a motor, 7 is a regulating coil bracket, 8 is a gas flow regulating valve, and 9 is a magnesia brick;

[0060] The molten pool is made of magnesia bricks; the material of the bottom of the molten pool is porous magnesia bricks; the pore size of the porous magnesia bricks is 0.1 mm; the thickness of the porous magnesia bricks is 10 cm;

[0061] like Figure 1 As shown, the molten pool is placed on a vibration platform; an opening is provided at the center of the vibration platform, and the argon supply device is connected to the molten pool through the opening;

[0062] like Figure 1 As shown, the argon delivery device is provided with an argon gas delivery pipeline; the argon gas delivery pipeline is provided at the opening; the argon gas delivery pipeline is fixed by an adjusting coil bracket; a gas flow regulating valve is provided near the opening of the argon gas delivery pipeline; the gas flow regulating valve is connected to the argon gas nozzle; the argon gas nozzle is tightly connected to the porous magnesia brick;

[0063] like Figure 1 As shown, a furnace cover is provided outside the molten pool; the furnace cover and the molten pool are sealed with magnesia sand to isolate the air;

[0064] A triangular magnesia brick is provided on the upper part of the molten pool;

[0065] The vibration platform is a lost foam casting vibration platform;

[0066] The exciting force of the vibration platform is 75KN;

[0067] The size of the vibration platform is 1.5m*1.5m; the bearing capacity of the vibration platform is ≥2 tons.

[0068] Example 1

[0069] A method for preparing a low-oxygen and low-nitrogen aluminum-niobium master alloy comprises the following steps:

[0070] (1) Weigh 47.2 kg of niobium pentoxide, 42.7 kg of aluminum particles, and 9 kg of potassium chlorate and dry them in different drying kilns for 6 hours at a drying temperature of 110°C. Then mix them on a clean mixing tray for 6 times to obtain a mixed material. 50 1mm; the purity of niobium pentoxide is 99.95%; the D 50 The thickness is 1mm; the purity of the aluminum source is 99.95%;

[0071] (2) Turn on the vibration platform and argon gas, pour the mixed material into the molten pool, stop feeding when the feeding height reaches 12 cm, wait for the material surface to be flat, and keep flowing argon gas for 3 minutes; then carry out the second feeding, stop feeding when the feeding height reaches 12 cm, stop feeding, wait for the material surface to be flat, and keep flowing argon gas for 6 minutes; then carry out the third feeding, stop feeding when the feeding height reaches 12 cm, stop feeding, wait for the material surface to be flat, and keep flowing argon gas for 12 minutes; finally, pour all the remaining materials into the built molten pool, wait for the material surface to be flat, and keep flowing argon gas for 24 minutes; turn off the argon gas to obtain a mixed material; wherein, the argon gas is bottom-blown argon gas; the argon gas flow rate is 10 L / min; the frequency of the vibration is 200 Hz;

[0072] (3) igniting the mixture obtained in step (2) by using a magnesium rod, and subjecting the mixture to a thermite reaction and furnace cooling in sequence under vibration conditions to obtain a low-oxygen and low-nitrogen aluminum-niobium master alloy; wherein the thermite reaction temperature is 2500° C., the time is 50 seconds, and the vibration frequency is 200 Hz.

[0073] The composition analysis of the upper region 1 and the lower region 2 of the low-oxygen and low-nitrogen aluminum-niobium master alloy prepared in Example 1 was performed, and the results are shown in Table 1.

[0074] Table 1 Composition of the low-oxygen and low-nitrogen aluminum-niobium master alloy prepared in Example 1 (wt%)

[0075] serial number Nb Fe Si C O N Al 1 59.55 0.08 0.11 0.022 0.008 0.010 margin 2 60.46 0.09 0.10 0.013 0.010 0.013 margin

[0076] As shown in Table 1, after the argon flow and vibration treatment, the oxygen content in the low-oxygen and low-nitrogen aluminum-niobium master alloy is about 0.01 wt%, and the nitrogen content is about 0.01 wt%.

[0077] The center of the low-oxygen and low-nitrogen aluminum-niobium master alloy prepared in Example 1 was sampled and subjected to a tensile test using an AGS-XD50KN universal tensile testing machine. The tensile test was conducted at room temperature with a strain rate of 1*10 -3 s -1 , the mechanical properties data are shown in Table 2.

[0078] Table 2 Mechanical properties of the low oxygen and low nitrogen aluminum-niobium master alloy prepared in Example 1

[0079] serial number Yield strength / MPa Tensile strength / MPa Elongation / % 1 340 511 9.8 2 365 548 7.2 3 342 520 7.5 average value 349 526.3 8.2

[0080] As shown in Table 2, the average yield strength of the low-oxygen and low-nitrogen aluminum-niobium master alloy is 349 MPa, the average tensile strength is 526.3 MPa, and the average elongation is 8.2%.

[0081] Example 2

[0082] A method for preparing a low-oxygen and low-nitrogen aluminum-niobium master alloy comprises the following steps:

[0083] (1) Weigh 60 kg of niobium pentoxide, 54.2 kg of aluminum particles, and 11.5 kg of potassium chlorate and dry them in different drying kilns for 6 hours at a drying temperature of 110°C. Then mix them on a clean mixing tray for 6 times to obtain a mixed material. 50 1mm; the purity of niobium pentoxide is 99.95%; the D 50 The thickness is 1mm; the purity of the aluminum source is 99.95%;

[0084] (2) Turn on the vibration platform and argon gas, pour the mixed material into the molten pool, stop feeding when the feeding height reaches 15 cm, wait for the material surface to be flat, and keep flowing argon gas for 3 minutes; then carry out the second feeding, stop feeding when the feeding height reaches 15 cm, stop feeding, wait for the material surface to be flat, and keep flowing argon gas for 6 minutes; then carry out the third feeding, stop feeding when the feeding height reaches 15 cm, stop feeding, wait for the material surface to be flat, and keep flowing argon gas for 12 minutes; finally, pour all the remaining materials into the built molten pool, wait for the material surface to be flat, and keep flowing argon gas for 24 minutes; turn off the argon gas to obtain a mixed material; wherein, the argon gas is bottom-blown argon gas; the argon gas flow rate is 12 L / min; the frequency of the vibration is 200 Hz;

[0085] (3) igniting the mixture obtained in step (2) by using a magnesium rod, and subjecting the mixture to a thermite reaction and furnace cooling in sequence under vibration conditions to obtain a low-oxygen and low-nitrogen aluminum-niobium master alloy; wherein the temperature of the thermite reaction is 2500° C., the time is 55 seconds, and the vibration frequency is 200 Hz.

[0086] The composition analysis of the upper region 1 and the lower region 2 of the low-oxygen and low-nitrogen aluminum-niobium master alloy prepared in Example 2 was performed. The results are shown in Table 3.

[0087] Table 3 Composition / wt% of the low-oxygen and low-nitrogen aluminum-niobium master alloy prepared in Example 2

[0088] serial number Nb Fe Si C O N Al 1 60.12 0.07 0.10 0.022 0.010 0.009 margin 2 60.55 0.08 0.10 0.024 0.012 0.013 margin

[0089] As shown in Table 3, after increasing the feed amount, the oxygen content in the low-oxygen and low-nitrogen aluminum-niobium master alloy is up to 0.012 wt %, and the nitrogen content is up to 0.013 wt %, which are not much different from the oxygen and nitrogen contents in Example 1.

[0090] The center of the low-oxygen and low-nitrogen aluminum-niobium master alloy prepared in Example 2 was sampled and subjected to a tensile test using an AGS-XD50KN universal tensile testing machine. The tensile test was conducted at room temperature with a strain rate of 1*10 -3 s -1 , the mechanical properties data are shown in Table 4.

[0091] Table 4 Mechanical properties data of low oxygen and low nitrogen aluminum-niobium master alloy prepared in Example 2

[0092] serial number Yield strength / MPa Tensile strength / MPa Elongation / % 1 356 498 9.2 2 350 502 9.0 3 333 470 8.1 average value 346.3 490 8.8

[0093] As shown in Table 4, the average yield strength of the low-oxygen and low-nitrogen aluminum-niobium master alloy is 346.3 MPa, the average tensile strength is 490 MPa, and the average elongation is 8.8%.

[0094] Example 3

[0095] A method for preparing a low-oxygen and low-nitrogen aluminum-niobium master alloy comprises the following steps:

[0096] (1) Weigh 72.0 kg of niobium pentoxide, 65.0 kg of aluminum particles, and 13.8 kg of potassium chlorate and dry them in different drying kilns for 6 hours at a drying temperature of 110°C. Then mix them on a clean mixing tray for 6 times to obtain a mixed material. 50 1mm; the purity of niobium pentoxide is 99.95%; the D 50 The thickness is 1mm; the purity of the aluminum source is 99.95%;

[0097] (2) Turn on the vibration platform and argon, pour the mixed material into the molten pool, stop adding when the feeding height reaches 15 cm, wait for the material surface to be flat, and keep passing argon for 3 minutes; then carry out the second feeding, stop adding when the feeding height reaches 15 cm, stop adding, wait for the material surface to be flat, and keep passing argon for 6 minutes; then carry out the third feeding, stop adding when the feeding height reaches 15 cm, stop adding, wait for the material surface to be flat, and keep passing argon for 12 minutes; then carry out the fourth feeding, stop adding when the feeding height reaches 15 cm, stop adding, wait for the material surface to be flat, and keep passing argon for 24 minutes; finally, pour all the remaining materials into the built molten pool, wait for the material surface to be flat, and keep passing argon for 48 minutes; turn off the argon to obtain a mixed material; wherein, the argon is bottom-blown argon; the argon flow rate is 12 L / min; the frequency of the vibration is 200 Hz;

[0098] (3) igniting the mixture obtained in step (2) by using a magnesium rod, and subjecting the mixture to a thermite reaction and furnace cooling in sequence under vibration conditions to obtain a low-oxygen and low-nitrogen aluminum-niobium master alloy; wherein the thermite reaction temperature is 2500° C., the time is 60 seconds, and the vibration frequency is 200 Hz.

[0099] The composition analysis of the upper region 1 and the lower region 2 of the low-oxygen and low-nitrogen aluminum-niobium master alloy prepared in Example 3 was performed. The results are shown in Table 5.

[0100] Table 5 Composition / wt% of the low-oxygen and low-nitrogen aluminum-niobium master alloy prepared in Example 3

[0101] serial number Nb Fe Si C O N Al 1 60.87 0.06 0.11 0.018 0.011 0.010 margin 2 60.41 0.08 0.10 0.020 0.012 0.012 margin

[0102] As shown in Table 5, after the feed amount is further increased, the oxygen content and nitrogen content in the low-oxygen and low-nitrogen aluminum-niobium master alloy are up to 0.012 wt %, and are not much different from those in Example 2.

[0103] The center of the low-oxygen and low-nitrogen aluminum-niobium master alloy prepared in Example 3 was sampled and subjected to a tensile test using an AGS-XD50KN universal tensile testing machine. The tensile test was conducted at room temperature with a strain rate of 1*10 -3 s -1 , the mechanical properties data are shown in Table 6.

[0104] Table 6 Mechanical properties of the low oxygen and low nitrogen aluminum-niobium master alloy prepared in Example 3

[0105]

[0106]

[0107] As shown in Table 6, the average yield strength of the low-oxygen and low-nitrogen aluminum-niobium master alloy is 368.3 MPa, the average tensile strength is 486.7 MPa, and the average elongation is 8.9%.

[0108] Comparative Example 1

[0109] The difference from Example 1 is that the vibration treatment and argon gas in step (2) are omitted, and other conditions remain unchanged.

[0110] The components of the upper region 1 and the lower region 2 of the aluminum-niobium master alloy prepared in Comparative Example 1 were analyzed, and the results are shown in Table 7.

[0111] Table 7 Composition / wt% of the aluminum-niobium master alloy prepared in Comparative Example 1

[0112] serial number Nb Fe Si C O N Al 1 59.22 0.07 0.12 0.023 0.038 0.024 margin 2 59.86 0.08 0.11 0.020 0.042 0.026 margin

[0113] As shown in Table 7, without the argon vibration treatment during the feeding process, the oxygen content in the aluminum-niobium master alloy reached 0.042 wt %, and the nitrogen content reached 0.026 wt %, which were significantly higher than those in Example 1.

[0114] The center of the aluminum-niobium master alloy prepared in Comparative Example 1 was sampled and subjected to a tensile test using an AGS-XD50KN universal tensile testing machine. The tensile test was conducted at room temperature with a strain rate of 1*10 -3 s -1 , the mechanical properties data are shown in Table 8.

[0115] Table 8 Mechanical properties of the aluminum-niobium master alloy prepared in Comparative Example 1

[0116] serial number Yield strength / MPa Tensile strength / MPa Elongation / % 1 280 410 6.5 2 305 423 7.3 3 313 442 7.1 average value 299.3 425 7.0

[0117] As shown in Table 8, the average yield strength, average tensile strength, and average elongation of the aluminum-niobium master alloy are 299.3 MPa, 425 MPa, and 7.0%, respectively. Comparing Example 1 with Example 1 shows that argon-assisted vibration treatment can significantly improve the toughness of the aluminum-niobium master alloy.

[0118] Comparative Example 2

[0119] The difference from Example 2 is that the vibration treatment and argon gas in step (2) are omitted, and other conditions remain unchanged.

[0120] The components of the upper region 1 and the lower region 2 of the aluminum-niobium master alloy prepared in Comparative Example 2 were analyzed, and the results are shown in Table 9.

[0121] Table 9 Composition / wt% of the aluminum-niobium master alloy prepared in Comparative Example 2

[0122] serial number Nb Fe Si C O N Al 1 59.58 0.08 0.10 0.023 0.041 0.028 margin 2 60.23 0.08 0.11 0.020 0.050 0.035 margin

[0123] As can be seen from Table 9, after increasing the feed rate, the oxygen content in the aluminum-niobium master alloy reaches a maximum of 0.050 wt%, and the nitrogen content reaches a maximum of 0.035 wt%, which are significantly higher than the oxygen and nitrogen contents in Example 2; and higher than the oxygen and nitrogen contents in Comparative Example 1. This is mainly because as the feed rate increases, the air in the gaps between the materials increases, and the oxygen and nitrogen content introduced during the reaction process increases accordingly. This further confirms that the greater the feed rate, the more significant the oxygen and nitrogen reduction effects of the present invention.

[0124] The center of the aluminum-niobium master alloy prepared in Comparative Example 2 was sampled and subjected to a tensile test using an AGS-XD50KN universal tensile testing machine. The tensile test was conducted at room temperature with a strain rate of 1*10 -3 s -1 , the mechanical properties data are shown in Table 10.

[0125] Table 10 Mechanical properties data of aluminum-niobium master alloy prepared in comparative example 2

[0126] serial number Yield strength / MPa Tensile strength / MPa Elongation / % 1 320 480 8.6 2 333 465 8.2 3 350 488 7.2 average value 334.3 477.7 8.0

[0127] As shown in Table 10, the average yield strength, average tensile strength, and average elongation of the aluminum-niobium master alloy are 334.3 MPa, 477.7 MPa, and 8.0%, respectively. Comparing Example 2 with Example 2 shows that argon-assisted vibration treatment can improve the toughness of the aluminum-niobium master alloy.

[0128] Comparative Example 3

[0129] The difference from Example 2 is that the vibration treatment in step (2) is omitted, and other conditions remain unchanged.

[0130] The components of the upper region 1 and the lower region 2 of the aluminum-niobium master alloy prepared in Comparative Example 3 were analyzed, and the results are shown in Table 11.

[0131] Table 11 Composition / wt% of the aluminum-niobium master alloy prepared in Comparative Example 3

[0132] serial number Nb Fe Si C O N Al 1 60.12 0.07 0.10 0.022 0.030 0.016 margin 2 59.92 0.06 0.09 0.026 0.032 0.020 margin

[0133] As shown in Table 11, without vibration treatment, the oxygen content in the aluminum-niobium master alloy reaches a maximum of 0.032 wt%, and the nitrogen content reaches a maximum of 0.020 wt%, which are slightly higher than the oxygen and nitrogen contents in Example 2 and lower than the oxygen and nitrogen contents in Comparative Example 2. This indicates that the oxygen and nitrogen reduction effects of argon treatment alone are not as good as those of argon plus vibration treatment.

[0134] The center of the aluminum-niobium master alloy prepared in Comparative Example 3 was sampled and subjected to a tensile test using an AGS-XD50KN universal tensile testing machine. The tensile test was conducted at room temperature with a strain rate of 1*10 -3 s -1 , the mechanical properties data are shown in Table 12.

[0135] Table 12 Mechanical properties of the aluminum-niobium master alloy prepared in Comparative Example 3

[0136] serial number Yield strength / MPa Tensile strength / MPa Elongation / % 1 320 488 8.2 2 315 475 7.3 3 310 473 8.1 average value 315 478.7 7.9

[0137] As shown in Table 12, the average yield strength of the aluminum-niobium master alloy is 315 MPa, the average tensile strength is 478.7 MPa, and the average elongation is 7.9%. Comparative Example 3 and Example 2 show that the strengthening effect of the aluminum-niobium master alloy by argon treatment alone is not as good as that by argon treatment plus vibration.

[0138] It can be seen from the examples and comparative examples that the aluminum-niobium master alloy prepared by the preparation method provided by the present invention is low in oxygen and nitrogen and has excellent strength and toughness.

[0139] The above is only a preferred embodiment of the present invention. It should be pointed out that for ordinary technicians in this technical field, several improvements and modifications can be made without departing from the principles of the present invention. These improvements and modifications should also be regarded as within the scope of protection of the present invention.

Claims

1. A method for preparing a low-oxygen and low-nitrogen aluminum-niobium master alloy, comprising the following steps: (1) mixing a niobium source, an aluminum source, and an oxidant, and then charging the mixture under argon gas and vibration conditions to obtain a mixture; (2) subjecting the mixture obtained in step (1) to a thermite reaction and cooling in sequence under vibration conditions to obtain a low-oxygen and low-nitrogen aluminum-niobium master alloy.

2. The preparation method according to claim 1, characterized in that In the step (1), the D of the niobium source and the aluminum source 50 Independently 1 to 2 mm.

3. The preparation method according to claim 1, characterized in that In the step (1), the mass ratio of the niobium source, the aluminum source and the oxidant is (5-5.5): (4.5-5): (1-1.2).

4. The preparation method according to claim 1, characterized in that The argon gas in step (1) is bottom-blown argon gas; the flow rate of the argon gas is 7 to 12 L / min.

5. The preparation method according to claim 1, characterized in that The frequencies of the vibration in step (1) and the vibration in step (2) are independently 150 to 200 Hz.

6. The preparation method according to claim 1, characterized in that In the step (1), the materials are added to the molten pool in batches, and the height of each batch of materials added to the molten pool is no more than 15 cm.

7. The preparation method according to claim 6, characterized in that After the first batch of materials are added to the molten pool, the argon gas introduction time is 3 to 5 minutes, after the second batch of materials are added to the molten pool, the argon gas introduction time is 6 to 10 minutes, and after the third batch of materials are added to the molten pool, the argon gas introduction time is 12 to 20 minutes. As the batches increase, the argon gas introduction time increases exponentially until the loading is completed.

8. The preparation method according to claim 6, characterized in that The molten pool is made of magnesia bricks, and the material of the bottom of the molten pool is porous magnesia bricks. The pore size of the porous magnesia bricks is ≤0.1mm, and the thickness of the porous magnesia bricks is ≥10cm.

9. The preparation method according to claim 6 or 8, characterized in that: The molten pool is placed on a vibration platform, an opening is provided at the center of the vibration platform, and the argon passing device is connected to the molten pool through the opening.

10. The low-oxygen and low-nitrogen aluminum-niobium master alloy prepared by the preparation method according to any one of claims 1 to 9, wherein the oxygen content of the low-oxygen and low-nitrogen aluminum-niobium master alloy is ≤0.012 wt%, and the nitrogen content is ≤0.013 wt%.

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