Nickel-lanthanum intermediate alloy for high-temperature alloy and preparation method of nickel-lanthanum intermediate alloy

Abstract

The invention discloses a nickel-lanthanum intermediate alloy for a high-temperature alloy. The nickel-lanthanum intermediate alloy consists of the following elements in percentage by mass: 5-32% of La, not more than 0.1% of Fe, not more than 0.1% of C, not more than 0.05% of O and the balance of Ni, the invention further discloses a preparation method of the nickel-lanthanum intermediate alloy for the high-temperature alloy, and the method comprises the following steps: step 1, putting a lanthanum block into the bottom of a crucible, uniformly laying a layer of carbon powder, loading a nickel block, vacuumizing, filling argon to reduce oxygen, and starting smelting to obtain a melt; and 2, cooling the melt to obtain a nickel-lanthanum intermediate alloy ingot, taking out the nickel-lanthanum intermediate alloy ingot, and crushing the nickel-lanthanum intermediate alloy ingot to obtain the nickel-lanthanum intermediate alloy for the high-temperature alloy. According to the nickel-lanthanum intermediate alloy, by limiting the component content, the nickel-based intermediate alloy with the La element mass fraction of 5%-32% is formed, the melting point is closer to that of high-temperature alloy matrix nickel, oxidation is not likely to happen, the high-temperature alloy smelting requirement can be met, and the nickel-lanthanum intermediate alloy is suitable for the technical field of alloy preparation.

Description

Technical Field

[0001] The present invention belongs to the technical field of alloy preparation, and in particular relates to a nickel-lanthanum master alloy for high-temperature alloys and a preparation method thereof. Background Art

[0002] Both GH5188 and GH3230 high-temperature alloys exhibit excellent high-temperature strength and oxidation resistance, and are widely used in high-temperature, corrosion-resistant components such as combustion chambers and tail nozzles in aircraft engines, as well as heat exchangers in the nuclear power industry. Both high-temperature alloys incorporate the element La, which effectively improves their hot workability and high-temperature creep resistance.

[0003] Currently, high-temperature alloy smelting is mainly carried out by directly adding elemental metal lanthanum. However, due to the activity and low melting point of lanthanum (920°C), it is extremely easy to oxidize and volatilize, which not only affects the effective addition of lanthanum, but also easily introduces impurities during the smelting of high-temperature alloys, thereby affecting the composition and properties of the alloy.

[0004] Therefore, in order to avoid the above problems, it is urgent to develop a nickel-lanthanum intermediate alloy that is not easily oxidized and volatilized and can meet the requirements of high-temperature alloy smelting and a preparation method thereof. Summary of the Invention

[0005] The technical problem to be solved by the present invention is to address the shortcomings of the above-mentioned prior art and provide a nickel-lanthanum master alloy for high-temperature alloys. By limiting the content of each component, the nickel-lanthanum master alloy forms a Ni-based master alloy with a lanthanum mass fraction of 5% to 32%. Compared with elemental lanthanum, the nickel-lanthanum master alloy is less susceptible to oxidation, easier to store and transport, and less likely to introduce inclusions during smelting. Furthermore, the nickel-lanthanum master alloy has a significantly higher melting point, closer to the melting point of the nickel or cobalt in the high-temperature alloy matrix, meeting the requirements of high-temperature alloy smelting and solving the problem of easy introduction of impurities and volatility when adding elemental lanthanum during the high-temperature alloy smelting process.

[0006] To solve the above technical problems, the technical solution adopted by the present invention is: a nickel-lanthanum master alloy for high-temperature alloys, characterized in that the nickel-lanthanum master alloy is composed of the following elements in mass fractions: La 5% to 32%, Fe not more than 0.1%, C not more than 0.1%, O not more than 0.05%, and the balance is Ni.

[0007] The present invention forms a nickel-lanthanum master alloy using Ni as a matrix and La, an element having good hot workability and high-temperature creep resistance. By limiting the content of each component, the melting point of the lanthanum element is increased from 920°C to 1270°C to 1400°C, which is closer to the melting points of nickel (1455°C) and cobalt (1493°C) in the high-temperature alloy matrix. This effectively avoids metallurgical problems such as easy burning and volatilization of the lanthanum element during the smelting process of the high-temperature alloy, and solves the problem of easy oxidation caused by the excessive activity of lanthanum and the introduction of impurities during smelting.

[0008] The above-mentioned nickel-lanthanum master alloy for high-temperature alloys is characterized in that the nickel-lanthanum master alloy is composed of the following elements in mass fraction: La 25% to 32%, Fe not more than 0.1%, C not more than 0.05%, O not more than 0.01%, and the balance is Ni.

[0009] In addition, the present invention also discloses a method for preparing a nickel-lanthanum master alloy for high-temperature alloys, characterized in that the method comprises the following steps:

[0010] Step 1: Place the lanthanum block at the bottom of the crucible, then evenly spread a layer of carbon powder and add the nickel block. Then, vacuum and fill with argon to reduce oxygen, and then start smelting to obtain a melt.

[0011] Step 2: Cool the melt obtained in step 1 to obtain a nickel-lanthanum intermediate alloy ingot, take it out and crush it to obtain a nickel-lanthanum intermediate alloy for high-temperature alloy.

[0012] The present invention places a highly active, low-melting-point (920°C) lanthanum block at the bottom of the furnace, tops it with a layer of carbon powder, and then adds a nickel block on top. This effectively prevents the rapid volatilization of lanthanum into the furnace during the smelting process, ensuring the stability of the alloy composition. The small amount of carbon powder added reduces lanthanum oxide produced by oxidation due to excessive activity, ensuring the purity of the final nickel-lanthanum intermediate alloy.

[0013] The aforementioned method for preparing a nickel-lanthanum master alloy for high-temperature alloys is characterized in that the carbon powder in step 1 has a purity greater than 99%, a particle size of 100-500 mesh, and a weight of 0.02-0.07% of the lanthanum block. The lanthanum block and nickel block both have a purity greater than 99.9%, and each block is 50-100 mm in size. By strictly controlling the purity and specifications of the carbon powder, lanthanum block, and nickel block, the present invention ensures the purity of the nickel-lanthanum master alloy while controlling the melting rate of the raw materials during smelting and preventing excessive melting times due to overly large nickel blocks. Furthermore, the addition of carbon powder is intended to reduce lanthanum oxide, which has oxidized due to its high activity, to metallic lanthanum during the smelting process.

[0014] The above-mentioned method for preparing a nickel-lanthanum master alloy for high-temperature alloys is characterized in that the vacuum melting in step 1 adopts a method of providing 1×10 -2 Pa or less vacuum environment melting equipment, the vacuum melting is vacuum induction melting or vacuum suspension melting, the vacuum melting process is: vacuum to 1 × 10 -3 Pa~6×10 -3Pa, then close the vacuum valve, and then fill with argon gas with a volume purity of more than 99.9999% to -60kPa~-10kPa, then start smelting, the smelting power is stabilized at 85kW~200kW, the smelting temperature is 1700℃~2000℃, and the smelting time after melting is 5min~20min; the number of vacuum smelting is 1 time~3 times. The present invention fully reduces the oxygen partial pressure in the furnace by evacuating to the above-mentioned high vacuum degree and filling with high-purity argon gas, on the one hand, avoiding the introduction of gaseous impurity elements (O, N, etc.) into the melt during the smelting process, and on the other hand, under high temperature and low oxygen partial pressure, more effectively reduces lanthanum oxide to metallic lanthanum through carbon powder. Selecting the appropriate smelting temperature, smelting time and smelting number can ensure that Ni and La are fully diffused and uniform, ensure that the alloy components are evenly distributed, and avoid excessively high smelting temperature or excessively long smelting time, which leads to La volatilization and unstable composition control.

[0015] The above-mentioned method for preparing a nickel-lanthanum master alloy for high-temperature alloys is characterized in that the cooling in step 2 is performed after the smelting is completed, and the ingot is cooled in the furnace for 50 to 80 minutes to form an alloy ingot, and the size after the crushing is 50 to 100 mm. The present invention obtains a nickel-lanthanum master alloy ingot through a reasonable cooling time and crushes it into a suitable size for direct use in high-temperature alloy smelting.

[0016] Compared with the prior art, the present invention has the following advantages:

[0017] 1. By limiting the content of each component, the present invention forms a Ni-based master alloy with a lanthanum mass fraction of 5% to 32%. Compared with elemental lanthanum, the melting point is significantly improved and closer to the melting points of nickel and cobalt in the high-temperature alloy matrix. It can effectively avoid metallurgical problems such as easy burning and volatilization of elemental lanthanum during the smelting process of the high-temperature alloy, and solve the problem of easy oxidation caused by excessive lanthanum activity and the introduction of impurities during smelting.

[0018] 2. The present invention takes into account that metallic lanthanum is inevitably oxidized to produce lanthanum oxide due to its high activity. In order to avoid the introduction of oxide inclusions into the nickel-lanthanum intermediate alloy, the design is to reduce lanthanum oxide to lanthanum by adding carbon powder. However, since the reduction process needs to be carried out at high temperature (≥1700°C) and low oxygen partial pressure, conventional melting equipment cannot achieve this. Therefore, the present invention can provide 1×10 -2 The smelting process is carried out in a vacuum environment below Pa in a smelting device, which can fully meet the production conditions of carbon reduction of lanthanum oxide and obtain high-purity nickel-lanthanum master alloy.

[0019] 3. The preparation method of the nickel-lanthanum master alloy proposed in the present invention is simple and can be used for large-scale industrial production.

[0020] The technical solution of the present invention is further described in detail below through the accompanying drawings and embodiments. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] Figure 1 This is a microscopic image of the nickel-lanthanum master alloy for high-temperature alloys prepared in Example 1 of the present invention.

[0022] Figure 2 This is the distribution diagram of Ni element in the nickel-lanthanum master alloy for high-temperature alloy prepared in Example 1 of the present invention.

[0023] Figure 3 This is the distribution diagram of La element in the nickel-lanthanum master alloy for high-temperature alloy prepared in Example 1 of the present invention. DETAILED DESCRIPTION

[0024] Example 1

[0025] The nickel-lanthanum master alloy for high-temperature alloys of this embodiment is composed of the following elements in mass fractions: 25% La, and the balance Ni and unavoidable impurities.

[0026] The preparation method of this embodiment comprises the following steps:

[0027] Step 1: Place a lanthanum block with a size of 50mm to 100mm and a purity greater than 99% at the bottom of the crucible, then evenly spread a layer of carbon powder with a mass purity of 99% and a particle size of 300 mesh, which is 0.05% of the weight of the lanthanum block, and then load a nickel block with a size of 50mm to 100mm and a purity greater than 99.9%, and then evacuate to 6×10 -3 Pa~1×10 -3 Pa range, then close the vacuum valve, fill with argon gas with a volume purity of more than 99.9999% to a range of -60kPa to -10kPa, then start melting, the melting power is stabilized at 150kW, the melting temperature is 1800℃, the melting time after melting is 15min, the number of vacuum melting is 2, and a melt is obtained;

[0028] Step 2: Cool the melt obtained in step 1 in a furnace to obtain a nickel-lanthanum master alloy ingot, which is then taken out and crushed into nickel-lanthanum master alloys for high-temperature alloys with a size of 50 mm to 100 mm.

[0029] The nickel-lanthanum master alloy for high-temperature alloy obtained in this example was subjected to element detection, and the results are shown in Table 1.

[0030] Table 1

[0031] element La Fe C O Mass fraction (%) 25.15 0.07 0.008 0.004

[0032] As shown in Table 1, the nickel-lanthanum master alloy for high-temperature alloys obtained in this embodiment has a low content of impurity elements, which can avoid affecting the performance of downstream high-temperature alloy materials.

[0033] The nickel-lanthanum master alloy for high-temperature alloy obtained in this embodiment was subjected to microstructure and energy spectrum analysis. Figures 1 to 3 As shown, the nickel and La elements are evenly distributed in the nickel-lanthanum master alloy for high-temperature alloy obtained in this embodiment without segregation.

[0034] Example 2

[0035] The nickel-lanthanum master alloy for high-temperature alloys of this embodiment is composed of the following elements in mass fractions: 5% La, and the balance being Ni and unavoidable impurities.

[0036] The preparation method of this embodiment comprises the following steps:

[0037] Step 1: Place a lanthanum block with a size of 50mm to 100mm and a purity greater than 99% at the bottom of the crucible, then evenly spread a layer of carbon powder with a mass purity of 99% and a particle size of 100 mesh, which is 0.02% of the weight of the lanthanum block, and then load a nickel block with a size of 50mm to 100mm and a purity greater than 99.9%, and then evacuate to 6×10 -3 Pa~1×10 -3 Pa range, then close the vacuum valve, fill with argon gas with a volume purity of more than 99.9999% to a range of -60kPa to -10kPa, then start melting, the melting power is stabilized at 200kW, the melting temperature is 1900℃, the melting time after melting is 20min, the number of vacuum melting is 3 times, and a melt is obtained;

[0038] Step 2: Cool the melt obtained in step 1 in a furnace to obtain a nickel-lanthanum master alloy ingot, which is then taken out and crushed into nickel-lanthanum master alloys for high-temperature alloys with a size of 50 mm to 100 mm.

[0039] The nickel-lanthanum master alloy for high-temperature alloy obtained in this example was subjected to elemental analysis. The results are shown in Table 2.

[0040] Table 2

[0041] element La Fe C O Mass fraction (%) 4.98 0.1 0.1 0.05

[0042] As shown in Table 2, the nickel-lanthanum master alloy for high-temperature alloys obtained in this embodiment has a low content of impurity elements, which can avoid affecting the performance of downstream high-temperature alloy materials.

[0043] Example 3

[0044] The nickel-lanthanum master alloy for high-temperature alloys of this embodiment is composed of the following elements in mass fractions: 20% La, and the balance Ni and unavoidable impurities.

[0045] The preparation method of this embodiment comprises the following steps:

[0046] Step 1: Place a lanthanum block with a size of 50mm to 100mm and a purity greater than 99% at the bottom of the crucible, then evenly spread a layer of carbon powder with a mass purity of 99% and a particle size of 500 mesh, which is 0.07% of the weight of the lanthanum block, and then load a nickel block with a size of 50mm to 100mm and a purity greater than 99.9%, and then evacuate to 6×10 -3 Pa~1×10 -3 Pa range, then close the vacuum valve, fill with argon gas with a volume purity of more than 99.9999% to a range of -60kPa to -10kPa, then start melting, the melting power is stabilized at 100kW, the melting temperature is 1700℃, the melting time after melting is 10min, the number of vacuum melting is 1 time, and a melt is obtained;

[0047] Step 2: Cool the melt obtained in step 1 in a furnace to obtain a nickel-lanthanum master alloy ingot, which is then taken out and crushed into nickel-lanthanum master alloys for high-temperature alloys with a size of 50 mm to 100 mm.

[0048] The nickel-lanthanum master alloy for high-temperature alloy obtained in this example was subjected to elemental analysis. The results are shown in Table 3.

[0049] Table 3

[0050] element La Fe C O Mass fraction (%) 20.03 0.06 0.07 0.01

[0051] As shown in Table 3, the nickel-lanthanum master alloy for high-temperature alloys obtained in this embodiment has a low content of impurity elements, which can avoid affecting the performance of downstream high-temperature alloy materials.

[0052] Example 4

[0053] The nickel-lanthanum master alloy for high-temperature alloys of this embodiment is composed of the following elements in mass fractions: 32% La, and the balance being Ni and unavoidable impurities.

[0054] The preparation method of this embodiment comprises the following steps:

[0055] Step 1: Place a lanthanum block with a size of 50mm to 100mm and a purity greater than 99% at the bottom of the crucible, then evenly spread a layer of carbon powder with a mass purity of 99% and a particle size of 300 mesh, which is 0.05% of the weight of the lanthanum block, and then load a nickel block with a size of 50mm to 100mm and a purity greater than 99.9%, and then evacuate to 6×10 -3 Pa~1×10 -3 Pa range, then close the vacuum valve, fill with argon gas with a volume purity of more than 99.9999% to a range of -60kPa to -10kPa, then start melting, the melting power is stabilized at 150kW, the melting temperature is 2000℃, the melting time after melting is 5min, the number of vacuum melting is 2 times, and a melt is obtained;

[0056] Step 2: Cool the melt obtained in step 1 in a furnace to obtain a nickel-lanthanum master alloy ingot, which is then taken out and crushed into nickel-lanthanum master alloys for high-temperature alloys with a size of 50 mm to 100 mm.

[0057] The nickel-lanthanum master alloy for high-temperature alloy obtained in this example was subjected to elemental analysis. The results are shown in Table 4.

[0058] Table 4

[0059] element La Fe C O Mass fraction (%) 31.96 0.1 0.05 0.01

[0060] As shown in Table 4, the nickel-lanthanum master alloy has a low content of impurity elements, which can avoid affecting the performance of downstream high-temperature alloy materials.

[0061] The above description is only a preferred embodiment of the present invention and does not limit the present invention in any way. Any simple modification, change and equivalent variation made to the above embodiment based on the technical essence of the present invention shall still fall within the scope of protection of the technical solution of the present invention.

Claims

1. A nickel-lanthanum master alloy for high-temperature alloys, characterized in that: The nickel-lanthanum master alloy consists of the following elements in mass fractions: Composition: La 5% to 32%, Fe not more than 0.1%, C not more than 0.1%, O not more than 0.05%, and the balance is Ni.

2. The nickel-lanthanum master alloy for high-temperature alloy according to claim 1, characterized in that: The nickel-lanthanum master alloy is composed of the following elements in mass fractions: La 25% to 32%, Fe not more than 0.1%, C not more than 0.05%, O not more than 0.01%, and the balance being Ni.

3. A method for preparing a nickel-lanthanum master alloy for high-temperature alloys as claimed in claim 1 or 2, characterized in that: The method comprises the following steps: Step 1: Place the lanthanum block at the bottom of the crucible, then evenly spread a layer of carbon powder and add the nickel block, then evacuate and fill with argon to reduce oxygen, and then start vacuum melting to obtain a melt; Step 2: Cool the melt obtained in step 1 to obtain a nickel-lanthanum intermediate alloy ingot, take it out and crush it to obtain a nickel-lanthanum intermediate alloy for high-temperature alloy.

4. The method according to claim 3, characterized in that The mass purity of the carbon powder in step 1 is greater than 99%, the particle size is 100 mesh to 500 mesh, and its weight is 0.02% to 0.07% of the lanthanum block. The mass purity of the lanthanum block and the nickel block are both greater than 99.9%, and the size of the lanthanum block and the nickel block are both 50 mm to 100 mm.

5. The method for preparing a nickel-lanthanum master alloy for high-temperature alloy according to claim 3, characterized in that: The vacuum melting in step 1 is carried out using 1×10 -2 Pa or less vacuum environment melting equipment, the vacuum melting is vacuum induction melting or vacuum suspension melting, the vacuum melting process is: vacuum to 1 × 10 -3 Pa~6×10 -3 Pa, then close the vacuum valve, and then fill with argon with a volume purity of more than 99.9999% to -60kPa~-10kPa, and then start smelting, the melting power is stabilized at 85kW~200kW, the melting temperature is 1700℃~2000℃, and the melting time after melting is 5min~20min; the number of vacuum melting is 1 to 3 times.

6. The method according to claim 3, characterized in that The cooling in step 2 is to cool the ingot in the furnace for 50 to 80 minutes after the smelting is completed to form an alloy ingot. The size of the ingot after crushing is 50 to 100 mm.

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