A preparation method of corrosion-resistant iron-aluminum alloy

Abstract

The present invention provides a method for preparing a corrosion-resistant iron-aluminum alloy, which relates to the technical field of anti-corrosion treatment of industrial metal consumables. The method mixes raw materials Si, Al, and Fe particles to obtain a mixed material; places the mixed material in a vacuum melting furnace and performs venting operations; before melting the alloy, repeatedly melts the Ti ingot to remove oxygen; after melting the Ti ingot, melts the mixed material again to obtain an alloy product; grinds and electro-polishes the obtained alloy product, and then performs a preheating treatment on it. After slowly cooling down, a corrosion-resistant FeAl alloy is obtained; during the preheating treatment, a successive oxygen reduction and dehumidification device is connected to the gas circuit to purify the protective gas. After the preheating treatment, the FeAl alloy added with Si has an electrochemical corrosion resistance 40 times that of the unheat-treated FeAl alloy, which can ensure that the FeAl alloy is not easily corroded in a humid environment and is beneficial to expanding its scope of use.

Description

Technical Field

[0001] The present invention relates to the technical field of anti-corrosion treatment of industrial metal consumables, and particularly relates to a method for preparing an anti-corrosion iron-aluminum (FeAl) alloy. Background Art

[0002] The FeAl alloy is mainly composed of iron (Fe) and aluminum (Al), and has a very high resistivity, low density, high hardness, good wear resistance, and good anti-vibration and impact resistance. The soft magnetic alloy device made of the FeAl alloy has the characteristics of small eddy current loss and light weight. However, the FeAl alloy itself also has many defects, which are mainly manifested in the fact that it is very easy to produce failure phenomena caused by electrochemical reaction corrosion when used in a humid environment. As a protective element, Al is added to iron to form an oxide layer during the oxidation process. However, in a humid environment, the FeAl alloy product itself is prone to form a primary battery reaction due to the addition of Al, resulting in a worse anti-electrochemical corrosion ability, which greatly limits its actual use range. Therefore, it is very necessary to explore the improvement of the corrosion resistance of the FeAl alloy.

[0003] Adding alloying elements is a common method to improve the anti-electrochemical corrosion ability of metals and their alloys. In the invention patent "A Method for Improving the Oxidation Resistance of Iron by a Self-Generated Non-Metal Oxide Composite Film" (Patent No. ZL201911044881.6), it involves adding a small amount of Si element to prepare an FeSi alloy. In this patent, with the help of a preheating treatment process, a SiO2 protective film is formed on the surface of the low-alloyed Fe-Si alloy to improve the high-temperature oxidation resistance and anti-electrochemical corrosion ability of the alloy. It is known that when the Fe-Si binary alloy is subjected to high-temperature preheating treatment, a stable and dense single-layer protective SiO2 adhesion film can be formed on the substrate surface, which can significantly improve the oxidation resistance of the alloy. However, the heat treatment conditions of this invention patent are relatively harsh, mainly manifested in that the required heat treatment temperature needs to be above 800 °C and the heat treatment time needs to be 24 h to ensure that the generated protective film is dense and uniform, resulting in too high energy consumption in the production process and being not conducive to large-scale preparation. In addition, this invention patent does not involve the anti-electrochemical corrosion ability of the SiO2 adhesion film in an electrochemical solution. This is because the average thickness of the SiO2 protective layer is only about 10 nm, which is not conducive to improving the anti-electrochemical corrosion ability. The reason for the relatively thin thickness of the SiO2 protective layer is related to the relatively slow self-diffusion rate of Si, making it difficult to generate a thicker protective layer. Therefore, considering the strong self-diffusion ability of Al, the research on improving the corrosion resistance of the FeAl alloy is extremely necessary. Summary of the Invention

[0004] The object of the present invention is to solve the problem that the heat treatment conditions in the prior art are relatively harsh, and the required heat treatment temperature needs to be above 800 °C and the heat treatment time needs to be 24 h to ensure that the generated protective film is dense and uniform, resulting in too high production costs, and a preparation method of a corrosion-resistant FeAl alloy is proposed.

[0005] In order to achieve the above object, the present invention adopts the following technical solutions:

[0006] A preparation method of a corrosion-resistant iron-aluminum alloy, comprising the following steps:

[0007] Step 1: Mix the raw materials Si, Al and Fe particles to obtain a mixed material;

[0008] Step 2: Place the mixed material obtained in Step 1 in a vacuum melting furnace, use a Ti ingot as a standard deoxidation sample, and perform a venting operation to make the entire melting process an argon protection environment;

[0009] Step 3: Before melting the alloy, first repeatedly melt and deoxidize the Ti ingot; after melting the Ti ingot, then melt the mixed material to obtain an alloy product;

[0010] Step 4: Grind the alloy product obtained in Step 3, then wash, polish, wash again, and finally dry it to obtain a processed alloy;

[0011] Step 5: Place the alloy processed in Step 4 in a tube furnace, introduce a protective atmosphere for preheating treatment, and slowly cool down after the preheating treatment is completed to obtain a corrosion-resistant FeAl alloy; during the preheating treatment process, connect a successive oxygen reduction and dehumidification device to the gas path to purify the hydrogen.

[0012] Preferably, in the mixed material described in Step 1, the mass fraction of Si is 0-1.0 wt%, the mass fraction of Al is 1.0 wt%, and the mass fraction of iron is 98.0-100.0 wt%.

[0013] Preferably, in the mixed material described in Step 1, the mass fraction of Si is 1.0 wt%, the mass fraction of Al is 1.0 wt%, and the mass fraction of iron is 98.0 wt%.

[0014] Preferably, the venting operation in Step 2 is specifically: evacuate the furnace body to a low vacuum of 10 -1 Pa, introduce high-purity argon, and perform the gas washing operation more than 5 times to make the oxygen concentration reach the lowest, evacuate to a high vacuum environment of 10 -4 Pa to exhaust all the oxygen in the melting furnace, and finally introduce argon to the equilibrium atmospheric pressure to make the entire melting process an argon protection environment.

[0015] Preferably, in step three, the mixed material is smelted, and each sample is smelted 2-4 times on each side, 30s-1min each time.

[0016] Preferably, in step four, the alloy product is mechanically polished successively with sandpaper of 400-7000 mesh; the electrolyte used for polishing is a mixed solution of perchloric acid and acetic acid. A Zhaoxin constant current source is adopted, the output current is 0.5-2A, the voltage is 3-5V. The FeAlSi alloy sample is placed at the anode, and iron sheets are placed on the left and right sides as the cathode. A preset current is passed through, and the polishing time is 1-2min.

[0017] Preferably, in step five, the temperature of the preheating treatment is 500°C-800°C, and the heat treatment furnace is kept warm for 60min-1440min.

[0018] Preferably, the protective atmosphere in step five is hydrogen generated by a hydrogen generator, or a mixed gas composed of this hydrogen and commercial high-purity argon.

[0019] Preferably, the cooling rate in step five is set to 1-2°C / min, and the cooling speed is 5-8°C / min.

[0020] Preferably, the sequential oxygen reduction and dehumidification device is a 3+5 oxygen reduction and dehumidification device, which consists of a first heating device, a second heating device, a third heating device, a first silica gel drying device, a second silica gel drying device, a first molecular sieve drying device, a second molecular sieve drying device and a phosphorus pentoxide drying device. The protective atmosphere in the hydrogen generator passes through the first heating device to heat the residual oxygen to react with hydrogen to generate water, and then successively passes through the first silica gel drying device and the first molecular sieve drying device for oxygen reduction and dehumidification, and then enters the second heating device for secondary heating to make the residual oxygen react with hydrogen to generate water again, and then successively passes through the second silica gel drying device, the second molecular sieve drying device and the phosphorus pentoxide drying device for oxygen reduction and dehumidification, and then enters the third heating device with two layers of oil-free graphite particles at the front end for reheating to make the residual oxygen or water molecules react with the graphite particles to generate carbon monoxide for oxygen reduction again.

[0021] Advantages of the present invention

[0022] The present invention provides a method for preparing a corrosion-resistant FeAl alloy. In this method, a small amount of non-metallic Si element is added to the FeAl alloy to form a ternary iron alloy. Preheating treatment is carried out in a protective atmosphere. During this process, alloying elements Al and Si segregate towards the alloy surface, forming a double-layer protective film of Al2O3 (thick) / SiO2 (thin) covering the surface of the FeAlSi ternary alloy. The SiO2 film hinders the diffusion of O into the alloy interior, inhibits the internal oxidation of Al in the alloy, thereby facilitating the further segregation of Al and forming a thicker and more stable Al2O3 protective layer, significantly improving the overall electrochemical corrosion resistance of the FeAl alloy. Compared with the prior art, for the alloy involved in the present invention after preheating treatment, the lattice distortion of Fe - Al is conducive to the diffusion of Si, so the time and temperature requirements for forming the SiO2 film are greatly reduced.

[0023] Research shows that the protective film formed by segregating Si to the metal surface in the binary Fe - Si alloy is relatively thin because Si has a weak affinity for O. During the preheating treatment process, Si does not undergo internal oxidation and has a low requirement for the oxygen partial pressure. The oxygen partial pressure in the annealing atmosphere of hydrogen can be as high as 1×10 -2 -10×10 -2 Pa. However, due to the weak self-diffusion ability of Si, the formed protective film is very thin. Therefore, although this protective film has strong antioxidant ability, its electrochemical corrosion resistance is poor. Compared with Si, Al has a very strong affinity for O. According to physical chemistry knowledge, at 500 - 800 °C, the equilibrium oxygen partial pressure for reacting with Al is at least 10 orders of magnitude lower than that of Si. Therefore, it can be known that during the preheating treatment process of the binary Fe - Al alloy, Al is very likely to undergo internal oxidation. This internal oxidation phenomenon significantly reduces the effective concentration of Al inside the FeAl alloy, ultimately making the amount of Al segregating to the surface scarce, and thus the protective film formed by segregating Al to the metal surface in the binary Fe - Al alloy is also very thin. In addition, the internal oxidation of the Al element during the heat treatment process will cause the enrichment of Al2O3 inside the alloy, which will generate stress concentration, resulting in a decrease in the plasticity of the alloy and an increase in brittleness. In an extreme case, when a large amount of Al2O3 exists, cracks will occur in the matrix of the FeAl alloy. Based on this, the present invention proposes that adding a small amount of Si to the Fe - Al alloy to form a SiO2 protective film on the surface of the ternary alloy can hinder the internal diffusion of O, reduce the O concentration inside the alloy, greatly inhibit the internal oxidation of Al, and facilitate the diffusion of Al to the surface to form a thicker Al2O3 protective film, and its protective effect is significantly enhanced. After the pretreatment process of the alloy of the present invention, the thicker Al2O3 protective film has a stronger electrochemical corrosion resistance effect, which can play a better strengthening role in improving the protection performance while saving costs.

[0024] In the present invention, when introducing a protective gas during the preheating treatment, the 3+5 oxygen reduction and dehumidification device is connected to the gas path, greatly reducing the oxygen concentration in hydrogen, thereby effectively reducing the oxygen concentration inside the alloy and avoiding the decrease in the Al concentration caused by internal oxidation in the alloy. It should be noted that if the sequential oxygen reduction and dehumidification device is not used, the oxygen concentration in the protective atmosphere will be maintained at a relatively high level. Even with a SiO2 protective layer, the oxygen concentration in the alloy cannot be effectively reduced, and thus the internal oxidation of Al in the alloy cannot be avoided.

[0025] The anti-corrosion FeAl alloy proposed by the present invention significantly enhances the anti-electrochemical corrosion ability of the FeAl alloy material, can ensure that FeAl material products are not easily corroded in a humid environment, expand the applicable range of the alloy, and extend the quality guarantee time of the alloy. The materials used are abundant in the earth's reserves, inexpensive and easily available, the operation process is simple and easy to repeat, the required conditions are simple and easy to achieve, and the manufacturing process meets environmental protection requirements, being green and pollution-free, which is of great significance to the development of modern metal material technology. Brief Description of the Drawings

[0026] Figure 1 High-magnification surface morphology diagram and EDS diagram of the heat-treated Fe-Al-Si alloy in Example 3;

[0027] Figure 2 EDS concentration depth acquisition diagram of the heat-treated Fe-Al-Si alloy in Example 3 of the present invention;

[0028] Figure 3 TEM cross-section characterization diagram and EDS analysis diagram of the heat-treated Fe-Al-Si alloy in Example 3 of the present invention;

[0029] Figure 4 Potentiodynamic polarization curves of the Fe-Al-Si alloys obtained in Comparative Examples 1-2 and Examples 1-3 of the present invention;

[0030] Figure 5 Surface morphology diagrams of the corroded Fe-Al-Si alloys obtained in Comparative Examples 1-2 and Examples 1-3 of the present invention;

[0031] Figure 6 Cross-section TEM and EDS diagrams of the heat-treated alloy obtained in Comparative Example 4 of the present invention;

[0032] Figure 7 EDS concentration depth distribution diagrams of Fe, Al, and O on the cross-section of Comparative Example 4 of the present invention;

[0033] Figure 8 Surface morphology diagram of the corroded alloy in Comparative Example 3 of the present invention;

[0034] Figure 9Surface morphology diagram after corrosion for Comparative Example 4 of the present invention;

[0035] Figure 10 Cross-sectional TEM and EDS diagrams after heat treatment obtained in Comparative Example 6 of the present invention;

[0036] Figure 11 EDS concentration depth distribution diagrams of Fe, Si, and O on the cross-section of Comparative Example 6 of the present invention;

[0037] Figure 12 Surface morphology diagram after corrosion for Comparative Example 6 of the present invention;

[0038] Figure 13 Surface morphology diagram after corrosion for Comparative Example 5 of the present invention;

[0039] Figure 14 Structural schematic diagram of the 3+5 oxygen-reducing and dehumidifying device in the present invention.

[0040] Figure 14 In it, 1, the first heating device; 2, the second heating device; 3, the third heating device; 4, oil-free graphite particles; 5, the first silica gel drying device with color change; 6, the second silica gel drying device with color change; 7, the first molecular sieve drying device; 8, the second molecular sieve drying device; 9, the phosphorus pentoxide drying device; 10, the tail gas discharge device; 11, the hydrogen generator; 12, the quartz boat; 13, the sample. Detailed implementation manners

[0041] A preparation method of a corrosion-resistant iron-aluminum alloy, comprising the following steps:

[0042] Step 1: Mix the raw materials Si, Al, and Fe particles to obtain a mixed material; in the mixed material, the mass fraction of Si is 0-1.0 wt%, the mass fraction of Al is 1.0 wt%, and the mass fraction of iron is 98.0-100.0 wt%. Preferably, the mass fraction of Si is 1.0 wt%, the mass fraction of Al is 1.0 wt%, and the mass fraction of iron is 98.0 wt%; both the raw materials Si and Al are in small particle form with a purity of 99.99%. Avoid using powdery raw materials to prevent dust aggregation during the melting process, which affects the alloy performance; avoid using massive raw materials to prevent uneven alloy melting;

[0043] Step 2: Place the mixed material from Step 1 in a vacuum melting furnace, use a Ti ingot as a standard deoxidation sample, and perform the venting operation. The specific operation is as follows: Pump the inside of the furnace to a low vacuum of 10 -1 Pa, introduce high-purity argon gas, and perform the gas washing operation repeatedly for more than 5 times to make the oxygen concentration reach the lowest. Then pump it to a high vacuum environment of 10 -4 Pa to exhaust all the oxygen in the melting furnace. Finally, introduce argon gas to the equilibrium atmospheric pressure to make the entire melting process in an argon gas protection environment;

[0044] Step 3: Before melting the alloy, first repeatedly melt the Ti ingot, preferably for more than 30 s each time, to remove oxygen; after melting the Ti ingot, then melt the mixed materials. During the melting of the mixture, turn on the electromagnetic stirring of the melting furnace, or manually turn over the iron mixture with a metal spoon in the melting furnace. After each turnover, the Ti ingot needs to be remelted to remove the oxygen that escapes due to the movement of the metal spoon. Preferably, each side of each sample is melted 2 - 4 times, 30 s - 1 min each time, to obtain the alloy product;

[0045] Step 4: Grind the alloy product obtained in Step 3, preferably by mechanical grinding with 400 - 7000 - mesh sandpaper, then put it into acetone and alcohol for ultrasonic cleaning to remove impurities; then carry out polishing. The electrolyte used for polishing is preferably a mixed solution of perchloric acid and acetic acid. Use a Zhaoxin constant - current source, with an output current of 0.5 - 2 A and a voltage of 3 - 5 V. Place the FeAlSi alloy sample at the anode, and place iron sheets on the left and right sides as the cathode, pass in the preset current, and the polishing time is 1 - 2 min; ultrasonically clean the electrolytically polished alloy with ethanol and deionized water again, and finally use a hair dryer to blow - dry it with cold air to obtain the treated alloy;

[0046] Step 5: Put the alloy treated in Step 4 into a tube furnace, and introduce a protective atmosphere for pre - heat treatment. The protective atmosphere can be hydrogen generated by a hydrogen generator, or a mixture of this hydrogen and commercial high - purity argon, and the hydrogen ratio is not less than 10%. The gas flow rate is preferably 280 - 320 cm 3 / min. The temperature of the pre - heat treatment is preferably 500°C - 800°C, more preferably 800°C. The heat treatment furnace is preferably kept warm for 60 min - 1440 min, more preferably 1440 min. After the pre - heat treatment is completed, slowly cool it down. Preferably, program - controlled temperature slow - down to 200°C and then cool it down to room temperature with the furnace. The cooling rate is preferably set at 1 - 2°C / min, and the cooling speed is preferably 5 - 8°C / min to obtain the corrosion - resistant FeAl alloy; during the pre - heat treatment process, connect a sequential oxygen - reduction and dehumidification device to the gas path to purify the protective gas.

[0047] According to the present invention, the sequential oxygen reduction and dehumidification device is a 3+5 oxygen reduction and dehumidification device (3-stage heating for oxygen reduction + 5-stage drying for dehumidification), which consists of a first heating device 1, a second heating device 2, a third heating device 3, a first silica gel drying device 5, a second silica gel drying device 6, a first molecular sieve drying device 7, a second molecular sieve drying device 8, and a phosphorus pentoxide drying device 9. Since the H2 gas generated by the hydrogen generator 11 contains a relatively high concentration of O2 and H2O, its purity does not meet the requirements of the present invention. It is difficult to reduce the concentrations of O2 and H2O to the required levels simultaneously by means of the commonly used copper heating oxygen removal method or the water removal methods using silica gel, molecular sieve, or phosphorus pentoxide. Therefore, the present invention uses a self-assembled 3+5 oxygen reduction and dehumidification device to simultaneously reduce water and oxygen in the protective atmosphere. The basic idea is that in each of the three heating processes, the residual oxygen can react with hydrogen to reduce the oxygen concentration. After the first two heating processes, drying can absorb as much water as possible to reduce the H2O equilibrium concentration. When heating for the last time, the residual O2 and H2O can react with C to generate CO, thereby further reducing the O2 and H2O equilibrium concentrations;

[0048] The hydrogen protective atmosphere generated in the hydrogen generator 11 passes through a quartz tube and is heated by the first heating device 1 at a temperature of 450°C, so that the residual oxygen reacts with H2 as much as possible to become H2O. Then it passes through the first silica gel drying device 5 and the first molecular sieve drying device 7 in sequence for dehumidification, and then enters the second heating device 2 for secondary heating at a temperature of 450°C to further make the residual oxygen react with H2 as much as possible to become H2O. Then it passes through the second silica gel drying device 6, the second molecular sieve drying device 8, and the phosphorus pentoxide drying device 9 in sequence for dehumidification, so as to reduce the residual oxygen and water concentrations in the hydrogen as much as possible. Then the protective atmosphere is introduced into the third heating device 3 to make the residual oxygen or water molecules react with graphite particles to generate carbon monoxide, achieving the purpose of oxygen reduction and dehumidification and further reducing the equilibrium O2 partial pressure and H2O partial pressure. Finally, it is discharged through the tail gas discharge device 10.

[0049] The third heating device 3 is a preheating treatment furnace, which is internally provided with more than two layers of quartz boats 12. The quartz boats 12 are provided with oil-free graphite particles 4, and there is also a sample 13. The sample 13 is placed in the quartz boat 12, and the oil-free graphite particles 4 are placed in front of the sample 13. The quartz boats 12 containing the oil-free graphite particles 4 are provided with more than two layers, aiming to increase the contact area between the graphite particles and the gas to make the reaction sufficient. The oil-free graphite particles 4 are obtained by subjecting commercial graphite particles to degreasing treatment in a vacuum box furnace at 1300°C for 8 hours. During the heat preservation process, high-purity argon gas needs to be continuously introduced.

[0050] According to thermodynamics knowledge, the reason for choosing the heating temperature at 450°C is that at this temperature, the conversion rate and reaction rate of the reaction of O2 and H2 to form H2O are both relatively high. It should be noted that the three heating and oxygen-reducing and dehumidifying devices are all indispensable, otherwise the concentrations of O2 and H2O cannot be reduced to the levels required by the present invention. The dehumidifying devices, including silica gel, molecular sieve, phosphorus pentoxide and oil-free graphite particles, are also indispensable. Only by fully removing moisture can the equilibrium oxygen concentration in hydrogen be effectively reduced. The structures of the first heating device 1, the second heating device 2, the third heating device 3, the first silica gel drying device 5, the second silica gel drying device 6, the first molecular sieve drying device 7, the second molecular sieve drying device 8, and the phosphorus pentoxide drying device 9 are not particularly limited, and they can be assembled using devices well-known in the art.

[0051] Next, the technical solutions in the embodiments of the present invention will be clearly and completely described in conjunction with the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments.

[0052] Comparative Example 1

[0053] The preparation method of the pure iron control group includes the following steps:

[0054] Step 1: Weigh pure Fe grains with a purity of 99.99%.

[0055] Step 2: Place the materials required for melting in the groove in the vacuum melting furnace, and use a titanium (Ti) ingot as a standard deoxidation sample; then perform the venting operation, pump the inside of the furnace to a low vacuum of 10 -1 Pa, introduce high-purity argon gas, and perform the gas washing operation repeatedly for more than 5 times to make the oxygen concentration reach the lowest, pump to a high vacuum environment of 10 -4 Pa to exhaust all the oxygen in the melting furnace, and finally introduce argon gas to the equilibrium atmospheric pressure to make the whole melting process in an argon gas protection environment;

[0056] Step 3: Before melting, first melt the Ti ingot repeatedly for more than 30 s each time for deoxidation. After melting the Ti ingot, then melt the materials. Each sample is melted 2-4 times on each side for 30 s each time to obtain pure iron products;

[0057] Step 4: Grind the melted alloy ingot with sandpaper, then put the pure iron ingot into acetone and alcohol in turn for ultrasonic cleaning to remove impurities. Subsequently, put the alloy into the electrolyte for electrolytic polishing, ultrasonically clean the electrolytically polished alloy with ethanol and deionized water again, and finally use a hair dryer to blow dry it with cold air.

[0058] Comparative Example 2

[0059] A method for preparing an FeAl alloy includes the following steps:

[0060] Step 1: Mix Si with a mass fraction of 1.0 wt% and a purity of 99.99%, Al with a mass fraction of 1.0 wt% and a purity of 99.99%, and pure Fe grains with a mass fraction of 98.0 wt% and a purity of 99.99%.

[0061] Step 2: Place the materials required for smelting in the groove of a vacuum melting furnace, and use a Ti ingot as a standard deoxidization sample; then perform the venting operation, pump the inside of the furnace to a low vacuum of 10 -1 Pa, introduce high-purity argon gas, and perform the gas washing operation repeatedly for more than 5 times to minimize the oxygen concentration, and then pump it to a high vacuum of 10 -4 Pa to exhaust all the oxygen in the melting furnace. Finally, introduce argon gas to the equilibrium atmospheric pressure to ensure that the entire smelting process is protected by an argon gas environment.

[0062] Step 3: Before smelting the alloy, first smelt the Ti ingot repeatedly for more than 30 s each time to remove oxygen; after smelting the Ti ingot, then smelt the mixed materials. Each sample is smelted 2 - 4 times on each side for 30 s each time to obtain an alloy product with uniform composition and excellent performance.

[0063] Step 4: Polish the smelted alloy ingot with sandpaper, then ultrasonically clean the alloy ingot in acetone and alcohol in sequence to remove impurities; then put the alloy into the electrolyte for electrolytic polishing, ultrasonically clean the electrolytically polished alloy with ethanol and deionized water, and finally use a hair dryer to blow dry it with cold air to obtain the FeAl alloy.

[0064] Example 1

[0065] A method for preparing a novel corrosion-resistant FeAl alloy, comprising the following steps:

[0066] Step 1: Mix Si with a mass fraction of 1.0 wt% and a purity of 99.99% and Al with a mass fraction of 1.0 wt% and a purity of 99.99% with pure Fe grains with a mass fraction of 98.0 wt% and a purity of 99.99%.

[0067] Step 2: Place the materials required for smelting in the groove of a vacuum melting furnace, and use a Ti ingot as a standard deoxidization sample; then perform the venting operation, pump the inside of the furnace to a low vacuum of 10 -1 Pa, introduce high-purity argon gas, and perform the gas washing operation repeatedly for more than 5 times to minimize the oxygen concentration, and then pump it to a high vacuum of 10 -4 Pa to exhaust all the oxygen in the melting furnace. Finally, introduce argon gas to the equilibrium atmospheric pressure to ensure that the entire smelting process is protected by an argon gas environment.

[0068] Step 3: Before melting the alloy, first repeatedly melt the Ti ingot for more than 30 s each time to remove oxygen. After melting the Ti ingot, then melt the mixed materials. Each sample is melted 2 - 4 times on each side, 30 s each time, to obtain an alloy product with uniform composition and excellent performance;

[0069] Step 4: Sand the alloy ingot obtained by melting, and then ultrasonically clean the alloy ingot in acetone and alcohol in sequence to remove impurities. Subsequently, put the alloy into the electrolyte for electrolytic polishing, ultrasonically clean the electrolytically polished alloy with ethanol and deionized water again, and finally use a hair dryer to blow dry it with cold air;

[0070] Step 5: Preheat the treated alloy in a tube furnace with pure H2 gas flowing through. The heat treatment temperature is 800 °C; keep it warm in the heat treatment furnace for 60 min, and program - control the temperature to slowly cool down to 200 °C and then cool it in the furnace to room temperature. The temperature - decreasing rate of the program - controlled temperature is set to 1 °C / min to obtain a corrosion - resistant FeAl alloy. During the whole pre - heat treatment process, H2 gas generated by a hydrogen generator is introduced, and the gas flow rate is 300 cm 3 / min. Connect a 3 + 5 oxygen - reducing and dehumidifying device to the gas path to provide oxygen - reducing and dehumidifying treatment for the H2 gas.

[0071] Example 2

[0072] A preparation method of a new type of corrosion - resistant FeAl alloy, comprising the following steps:

[0073] Step 1: Mix Si with a mass fraction of 1.0 wt% and a purity of 99.99%, Al with a mass fraction of 1.0 wt% and a purity of 99.99%, and pure Fe particles with a mass fraction of 98.0 wt% and a purity of 99.99%;

[0074] Step 2: Place the materials required for melting in the groove of a vacuum melting furnace, and use the Ti ingot as a standard oxygen - removing sample; then perform the air - venting operation. Pump the inside of the furnace body to a low vacuum of 10 -1 Pa, introduce high - purity argon gas, and repeatedly perform the gas - washing operation more than 5 times to make the oxygen concentration reach the lowest. Pump it to a high vacuum environment of 10 -4 Pa to exhaust all the oxygen in the melting furnace. Finally, introduce argon gas to the equilibrium atmospheric pressure to make the whole melting process in an argon - protected environment;

[0075] Step 3: Before melting the alloy, first repeatedly melt the Ti ingot for more than 30 s each time to remove oxygen. After melting the Ti ingot, then melt the mixed materials. Each sample is melted 2 - 4 times on each side, 30 s each time, to obtain an alloy product with uniform composition and excellent performance;

[0076] Step 4: Polish the alloy ingot obtained by melting with sandpaper, then ultrasonically clean the alloy ingot successively in acetone and alcohol to remove impurities. Subsequently, put the alloy into the electrolyte for electrolytic polishing, ultrasonically clean the electrolytically polished alloy with ethanol and deionized water again, and finally blow-dry it with a hair dryer using cold air;

[0077] Step 5: Preheat-treat the processed alloy in a tube furnace with pure H2 gas flowing through. The heat treatment temperature is 800 °C; keep it warm in the heat treatment furnace for 720 min, and program-control the temperature to slowly cool down to 200 °C and then cool it in the furnace to room temperature. The programmed temperature reduction rate is set to 1 °C / min to obtain the corrosion-resistant FeAl alloy. During the whole preheat-treatment process, H2 gas generated by a hydrogen generator is introduced, and the gas flow rate is 300 cm 3 / min. Connect a 3+5 oxygen-reducing and dehumidifying device to the gas path to provide oxygen-reducing and dehumidifying treatment for the H2 gas.

[0078] Example 3

[0079] A preparation method of a new type of corrosion-resistant FeAl alloy, comprising the following steps:

[0080] Step 1: Mix Si with a mass fraction of 1.0 wt% and a purity of 99.99% and Al with a mass fraction of 1.0 wt% and a purity of 99.99% with pure Fe particles with a mass fraction of 98.0 wt% and a purity of 99.99%;

[0081] Step 2: Place the materials required for melting in the groove of a vacuum melting furnace, and use a Ti ingot as a standard deoxidation sample; then perform the air venting operation, pump the inside of the furnace body to a low vacuum of 10 -1 Pa, introduce high-purity argon gas, and perform the gas washing operation more than 5 times repeatedly to make the oxygen concentration reach the lowest, and pump it to a high vacuum environment of 10 -4 Pa to exhaust all the oxygen in the melting furnace. Finally, introduce argon gas to the equilibrium atmospheric pressure to make the whole melting process be in an argon gas protection environment;

[0082] Step 3: Before melting the alloy, first melt the Ti ingot repeatedly for more than 30 s each time to remove oxygen. After melting the Ti ingot, then melt the mixed materials. Each sample is melted 2 - 4 times on each side, 30 s each time, to obtain an alloy product with uniform composition and excellent performance;

[0083] Step 4: Polish the alloy ingot obtained by melting with sandpaper, then ultrasonically clean the alloy ingot successively in acetone and alcohol to remove impurities. Subsequently, put the alloy into the electrolyte for electrolytic polishing, ultrasonically clean the electrolytically polished alloy with ethanol and deionized water again, and finally blow-dry it with a hair dryer using cold air;

[0084] Step 5: Preheat the processed alloy in a tube furnace with pure H2 gas flowing through. The heat treatment temperature is 800 °C; keep it in the heat treatment furnace for 1440 min, and program the temperature control to slowly cool down to 200 °C and then cool with the furnace to room temperature. The temperature reduction rate of the programmed temperature control is set to 1 °C / min to obtain the corrosion-resistant FeAl alloy. During the whole preheating process, H2 gas generated by a hydrogen generator is introduced, and the gas flow rate is 300 cm 3 / min. Connect a 3+5 oxygen reduction and dehumidification device to the gas path to provide oxygen reduction and dehumidification treatment for the H2 gas.

[0085] Comparative Example 3

[0086] The Fe-Al binary alloy used for comparison with a new method for preparing a corrosion-resistant FeAl alloy includes the following steps:

[0087] Step 1: Mix Al with a mass fraction of 1.0 wt% and a purity of 99.99% with pure Fe grains with a mass fraction of 99.0 wt% and a purity of 99.99%.

[0088] Step 2: Place the materials required for melting in the groove of a vacuum melting furnace, and use a Ti ingot as a standard deoxidation sample; then perform the venting operation, pump the inside of the furnace body to a low vacuum of 10 -1 Pa, introduce high-purity argon gas, and perform the gas washing operation more than 5 times repeatedly to make the oxygen concentration reach the lowest, and pump it to a high vacuum environment of 10 -4 Pa to exhaust all the oxygen in the melting furnace. Finally, introduce argon gas to the equilibrium atmospheric pressure to make the whole melting process an argon gas protection environment;

[0089] Step 3: Before melting the alloy, first melt the Ti ingot repeatedly for more than 30 s each time for deoxidation. After melting the Ti ingot, then melt the mixed materials. Each sample is melted 2-4 times on each side, 30 s each time, to obtain an alloy product with uniform composition and excellent performance;

[0090] Step 4: Grind the melted alloy ingot with sandpaper, then put the alloy ingot into acetone and alcohol in turn for ultrasonic cleaning to remove impurities. Subsequently, put the alloy into the electrolyte for electrolytic polishing, and then ultrasonically clean the electrolytically polished alloy with ethanol and deionized water, and finally use a hair dryer to blow dry it with cold air.

[0091] Comparative Example 4

[0092] The Fe-Al binary alloy used for comparison with a new method for preparing a corrosion-resistant FeAl alloy includes the following steps:

[0093] Step 1: Mix Al with a mass fraction of 1.0 wt% and a purity of 99.99% with pure Fe grains with a mass fraction of 99.0 wt% and a purity of 99.99%.

[0094] Step 2: Place the materials required for melting in the groove inside the vacuum melting furnace, and use a Ti ingot as the standard deoxidization sample; then perform the venting operation, evacuate the furnace body to a low vacuum of 10 -1 Pa, introduce high-purity argon gas, and perform the gas washing operation repeatedly for more than 5 times to minimize the oxygen concentration, and then evacuate to a high vacuum of 10 -4 Pa to exhaust all the oxygen in the melting furnace. Finally, introduce argon gas to the equilibrium atmospheric pressure to ensure that the melting process is under an argon gas protection environment throughout;

[0095] Step 3: Before melting the alloy, first melt the Ti ingot repeatedly for more than 30 s each time to remove oxygen. After melting the Ti ingot, then melt the mixed materials. Each sample is melted 2 - 4 times on each side for 30 s each time to obtain an alloy product with uniform composition and excellent properties;

[0096] Step 4: Grind the melted alloy ingot with sandpaper, then place the alloy ingot in acetone and alcohol in sequence for ultrasonic cleaning to remove impurities. Subsequently, put the alloy into the electrolyte for electrolytic polishing, then ultrasonically clean the electrolytically polished alloy with ethanol and deionized water, and finally use a hair dryer to blow dry it with cold air;

[0097] Step 5: Preheat the treated alloy in a tubular furnace with pure H2 gas flowing through it. The heat treatment temperature is 800 °C; keep it in the heat treatment furnace for 1440 min, and program control the temperature to slowly cool down to 200 °C and then cool it in the furnace to room temperature. The temperature reduction rate of the program control is set at 1 °C / min to provide deoxidization and dehumidification treatment for the H2 gas. During the preheat treatment process, H2 gas generated by a hydrogen generator is introduced throughout, and the gas flow rate is 300 cm 3 / min, and connect the 3 + 5 deoxidization and dehumidification device to the gas path.

[0098] Comparative Example 5

[0099] The Fe - Si binary alloy used for comparison with a new method for preparing an anti - corrosion FeAl alloy includes the following steps:

[0100] Step 1: Mix Si with a mass fraction of 2.0 wt% and a purity of 99.99% with pure Fe grains with a mass fraction of 98.0 wt% and a purity of 99.99%;

[0101] Step 2: Place the materials required for melting in the groove inside the vacuum melting furnace, and use a Ti ingot as the standard deoxidization sample; then perform the venting operation, evacuate the furnace body to a low vacuum of 10 -1 Pa, introduce high - purity argon gas, and perform the gas washing operation repeatedly for more than 5 times to minimize the oxygen concentration, and then evacuate to a high vacuum of 10 -4 Pa to exhaust all the oxygen in the melting furnace. Finally, introduce argon gas to the equilibrium atmospheric pressure to ensure that the melting process is under an argon gas protection environment throughout;

[0102] Step 3: Before melting the alloy, first repeatedly melt the Ti ingot for more than 30 s each time to remove oxygen. After melting the Ti ingot, then melt the mixed materials. Each sample is melted 2 - 4 times on each side for 30 s each time to obtain an alloy product with uniform composition and excellent properties;

[0103] Step 4: Sandpaper the alloy ingot obtained by melting, then ultrasonically clean the alloy ingot in acetone and alcohol in sequence to remove impurities. Subsequently, put the alloy into the electrolyte for electrolytic polishing, ultrasonically clean the electrolytically polished alloy with ethanol and deionized water, and finally use a hair dryer to blow dry with cold air.

[0104] Comparative Example 6

[0105] The Fe - Si binary alloy used for comparison with a new anti - corrosion FeAl alloy preparation method includes the following steps:

[0106] Step 1: Mix Si with a mass fraction of 2.0 wt% and a purity of 99.99% and pure Fe grains with a mass fraction of 98.0 wt% and a purity of 99.99%;

[0107] Step 2: Place the materials required for melting in the groove of a vacuum melting furnace, and use the Ti ingot as a standard deoxidation sample; then perform the venting operation, pump the inside of the furnace to a low vacuum of 10 -1 Pa, introduce high - purity argon gas, and repeatedly perform the gas washing operation more than 5 times to make the oxygen concentration reach the lowest, then pump to a high vacuum environment of 10 -4 Pa to exhaust all the oxygen in the melting furnace, and finally introduce argon gas to the equilibrium atmospheric pressure to make the whole melting process in an argon - protected environment;

[0108] Step 3: Before melting the alloy, first repeatedly melt the Ti ingot for more than 30 s each time to remove oxygen. After melting the Ti ingot, then melt the mixed materials. Each sample is melted 2 - 4 times on each side for 30 s each time to obtain an alloy product with uniform composition and excellent properties;

[0109] Step 4: Sandpaper the alloy ingot obtained by melting, then ultrasonically clean the alloy ingot in acetone and alcohol in sequence to remove impurities. Subsequently, put the alloy into the electrolyte for electrolytic polishing, ultrasonically clean the electrolytically polished alloy with ethanol and deionized water, and finally use a hair dryer to blow dry with cold air;

[0110] Step 5: Preheat the processed alloy in a tube furnace with pure H2 gas flowing through it. The heat treatment temperature is 800 °C; keep it insulated in the heat treatment furnace for 1440 min, and then program the temperature to slowly decrease to 200 °C and then cool it to room temperature with the furnace. The temperature decrease rate of the programmed temperature control is set to 1 °C / min. During the whole preheating process, H2 gas generated by the hydrogen generator is introduced, and the gas flow rate is 300 cm 3 / min. Connect the 3+5 oxygen reduction and dehumidification device to the gas path to provide oxygen reduction and dehumidification treatment for the H2 gas.

[0111] In the present invention, experimental analysis is carried out on the above-mentioned embodiments and comparative examples, and the following conclusions are obtained:

[0112] Refer to Figure 1 , which is the high-magnification surface morphology diagram and EDS diagram of Example 3. Among them, Figures 1a and 1b represent the morphology diagrams at different magnifications, and Figures 1c, 1d, 1e, and 1f represent the EDS diagrams of Al, Si, O, and Fe elements respectively. It can be seen from the figure that the surface protective layer of Example 3 is dense and the distributions of Al, Si, O, and Fe elements are uniform.

[0113] Refer to Figure 2 , which is the EDS concentration depth acquisition image of the Fe-Al-Si alloy after heat treatment in Example 3. From the curves of the element contents of Fe, Si, Al, and O changing with the concentration on the cross-section of Example 3, the acquisition area is Figure 2 , it can be found that as the depth increases, the concentrations of Al and O gradually increase, but the Fe concentration gradually decreases from a lower level to a negligible level. When the depth reaches around 15 nm, the contents of Al and O rapidly rise from 0 to the highest, while other elements can hardly be detected, and the high-content Al-O layer lasts for about 100 nm. As the depth further increases, an enrichment area of Si starts to be detected after the Al-O layer. After that, as the depth increases, the Fe content starts to increase sharply, indicating that this part is the matrix area of Example 3. This shows that a SiO2 transition layer is generated on the surface of Example 3 during the heat treatment. Outside the SiO2 transition layer is the Al2O3 protective layer. That is to say, a self-generated Al2O3 / SiO2 composite passivation film is formed on the surface of Example 3.

[0114] Refer to Figure 3, Cross-sectional characterization and EDS analysis diagrams of the heat-treated Fe-Al-Si alloy in Example 3 using a transmission electron microscope. Among them, 3a represents the transmission electron microscope image of the cross-section of Example 3, 3b represents the high-resolution transmission electron microscope image of the cross-section of Example 3, 3c represents the TEM image and EDS image of Example 3, and (3d - 3g) represent the EDS spectra of Fe, O, Al, and Si in Example 3, respectively. From the transmission electron microscope image of the cross-section, it can be found that there is a uniform Al2O3 protective film covering the surface layer of Example 3, and almost no internal oxidation of Al is detected in the matrix. This indicates that the doping of Si not only successfully inhibits the internal oxidation of Al but also significantly increases the thickness of the surface Al2O3 protective film. The EDS image also shows that the surface layer is a dense and relatively thick Al2O3 protective film, and a thin SiO2 transition layer with a thickness of about 10 nm is formed between the Al2O3 and the matrix. This further proves that a self-generated Al2O3 / SiO2 composite passivation film is formed on the surface of Example 3.

[0115] See Figure 4 , The potentiodynamic polarization curves of Comparative Examples 1 - 2 and Examples 1 - 3, where each curve represents the potentiodynamic polarization curve, and the corrosion current (I corr ) can be obtained by extrapolation method, as shown in Table 1. The corrosion currents of Comparative Examples 1 - 2, Examples 1 - 3, and Comparative Examples 3 - 6 are 35.9 μA / cm -2 , 32.3 μA / cm -2 , 11.3 μA / cm -2 , 23.1 μA / cm -2 , 2.0 μA / cm -2 , 79.6 μA / cm -2 , 9.8 μA / cm -2 , 29.6 μA / cm -2 , 33.8 μA / cm -2 . The corrosion potentials (E corr)They are -0.86V, -0.82V, -0.81V, -0.78V, -0.75V, -0.81V, -0.87V, -0.85V, -0.92V respectively. Compared with Comparative Example 1 and Comparative Example 2, the corrosion current of Example 3 decreased by one order of magnitude. Among them, Example 3 has strong corrosion resistance, and its anti-electrochemical corrosion ability has increased by more than one order of magnitude. Moreover, with the increase of the heat treatment temperature, its corrosion resistance shows an increasing trend. This is because with the increase of the heat treatment time, the thickness and compactness of the surface protective film are also enhanced. Compared with Comparative Example 3, the corrosion current of Example 3 is only 1 / 40 of it, indicating that under the pre-heat treatment conditions, the anti-electrochemical corrosion ability of the FeAl alloy after adding Si is 40 times higher than that of the FeAl alloy without pre-heat treatment. It should be noted here that Comparative Example 3 and Comparative Example 4 are Fe-Al binary alloys before and after heat treatment respectively. After forming the Al2O3 protective film through pre-heat treatment, its electrochemical corrosion current is only 1 / 8 of that of the sample without pre-heat treatment, and the improvement of its anti-corrosion ability is far from that of Example 3. In addition, Comparative Example 5 and 6 are Fe-Si binary alloys before and after pre-heat treatment respectively. After forming the SiO2 protective film through heat treatment, its electrochemical corrosion performance has decreased slightly, which further illustrates the excellent anti-electrochemical corrosion performance of the Al2O3 / SiO2 composite passivation film generated in Example 3 of the present invention.

[0116] Table 1 shows the corrosion current data of the FeAl alloys obtained in Comparative Examples 1-2, Examples 1-3 and Comparative Examples 3-6 of the present invention

[0117] Table 1

[0118]

[0119] Refer to Figure 5 FIG. 5 shows the surface morphology diagrams after corrosion of Comparative Examples 1-2 and Examples 1-3, where 5a represents Comparative Example 1, 5b represents Comparative Example 2, 5c represents Example 1, 5d represents Example 2, and 5e represents Example 3. It can be found from the figure that the corrosion of Comparative Example 1 is the most serious, and severe pitting corrosion areas appear on the surface. The surface after corrosion of Comparative Example 2 is less corroded than that of pure Fe, but there is also relatively serious corrosion. No obvious corrosion was found on the surface of Example 1, but it was found that slight cracks began to appear on its surface after corrosion. This is because the heat treatment time of Example 1 is short, and the thickness of the surface oxide film is thin, and the surface oxide film begins to crack after corrosion. However, no obvious corrosion areas were found on the surfaces of Example 2 and Example 3, indicating that Example 2 and Example 3 have excellent anti-electrochemical corrosion performance. This also shows that a higher heat treatment time is beneficial to the growth of the oxide film.

[0120] Refer to Figure 6Cross-sectional TEM and EDS diagrams of Comparative Example 4, where 6a represents the TEM image of Comparative Example 4 after heat treatment, and 6(b-d) represent the EDS spectra of Al, Fe, and O, respectively. We found the phenomenon of enrichment of Al and O in the matrix in its cross section, which will lead to a decrease in the mechanical properties of the material, and cracks and stress concentration will occur during use, resulting in the failure of the material. The SiO2 protective layer in Comparative Example 3 can protect the internal matrix metal and promote the segregation of Al to the surface to avoid enrichment in the matrix.

[0121] See Figure 7 EDS concentration-depth distribution diagrams of Fe, Al, and O on the cross section of Comparative Example 4. The concentration-depth curves show that enrichment regions of Al and O appear near the surface, and there is no Fe in this part of the enrichment region, indicating that a thin Al2O3 protective layer about 10 nm thick was formed on the surface of Comparative Example 4 during pre-heat treatment. The formation of the Al2O3 protective layer originated from the outward diffusion of Al. It should be noted that even inside the matrix, the signal of O was detected, indicating that part of O diffused into the interior of the alloy matrix of Comparative Example 4, but its content was inconsistent with any stoichiometric iron oxide, indicating that part of O diffused into the matrix interior and caused oxidation of the matrix, that is, the Al2O3 protective layer cannot provide complete protection for the matrix like the SiO2 and Al2O3 double protective layers in Example 2 and Example 3.

[0122] See Figure 8 and Figure 9 Surface morphology diagrams of Comparative Examples 3-4 after corrosion. Comparative Example 4 has less corrosion than Comparative Example 3, and no serious corrosion points were found. Its corrosion is uniform corrosion on the surface. Although the Al2O3 protective layer formed during heat treatment plays a protective role for the matrix, the improvement of the electrochemical corrosion resistance of the alloy is very limited.

[0123] See Figure 10 Cross-sectional TEM and EDS diagrams of Comparative Example 6 after heat treatment, where 10a represents the transmission electron microscope image of the cross section of Comparative Example 6, 10b represents the high-resolution transmission electron microscope image of the cross section of Comparative Example 6, 10c represents the TEM image and EDS image of Comparative Example 6, and (10d-10g) represent the EDS spectra of Fe, O, Si, and Pt in Comparative Example 6, respectively. It can be seen that a SiO2 protective layer was formed on the surface of the Fe matrix, and the cross-sectional thickness of the protective layer can be seen to be uniform, about 10 nm.

[0124] See Figure 11 EDS concentration-depth distribution diagrams of Fe, Si, and O on the cross section of Comparative Example 6. After the formation of the SiO2 protective layer on the surface, the outward diffusion process of iron ions will be hindered by the SiO2 protective layer, but this cannot improve its electrochemical corrosion resistance.

[0125] See Figure 12 and Figure 13 are the surface morphology diagrams after corrosion of Comparative Example 6 and Comparative Example 5 respectively. It can be seen from the figures that the corrosion degrees of Comparative Example 5 and Comparative Example 6, which represent before and after heat treatment respectively, are relatively serious, and there are a large number of corrosion products. This also indicates that the SiO2 single-layer film formed by heat treatment has poor anti-electrochemical corrosion performance. Therefore, it also shows the excellent anti-electrochemical corrosion effect of the self-generated Al2O3 / SiO2 composite passivation film in this patent compared with the SiO2 single-layer film.

[0126] The above is only a preferred specific embodiment of the present invention, but the protection scope of the present invention is not limited thereto. Any person skilled in the art within the technical scope disclosed by the present invention, according to the technical solution and inventive concept of the present invention, making equivalent substitutions or changes, should be covered within the protection scope of the present invention.

Claims

1. A preparation method of a corrosion-resistant iron-aluminum alloy, characterized in that, It includes the following steps: Step 1: Mix raw materials Si, Al and Fe particles to obtain a mixed material; Step 2: Place the mixed material from Step 1 into a vacuum melting furnace, use a Ti ingot as a standard deoxidation sample, conduct venting operations to ensure an argon gas protection environment throughout the melting process; Step 3: Before melting the alloy, first repeatedly melt and deoxidize the Ti ingot; After melting the Ti ingot, then melt the mixed material to obtain an alloy product; Step 4: Grind the alloy product obtained in Step 3, then clean, polish, clean again, and finally dry it to obtain a processed alloy; Step 5: Place the alloy processed in Step 4 into a tube furnace, introduce a protective atmosphere for preheating treatment. After the preheating treatment ends, slowly cool it down. Program-controlled temperature reduction is carried out slowly until it reaches 200 °C and then it is cooled with the furnace to room temperature. The cooling rate is set at 1-2 °C / min, and the cooling speed is 5-8 °C / min to obtain a corrosion-resistant FeAl alloy; during the preheating treatment process, a sequential oxygen reduction and dehumidification device is connected to the gas path to purify the protective gas. In the mixed material described in Step 1, the mass fraction of Si is 1.0 wt%, the mass fraction of Al is 1.0 wt%, and the mass fraction of iron is 98.0 wt%; The temperature of the preheating treatment in Step 5 is 500 °C - 800 °C, and the heat treatment furnace is kept warm for 60 min - 1440 min; The protective atmosphere described in Step 5 is hydrogen generated by a hydrogen generator or a mixture of this hydrogen and commercial high-purity argon; The sequential oxygen reduction and dehumidification device is a 3+5 oxygen reduction and dehumidification device, which consists of a first heating device, a second heating device, a third heating device, a first silica gel drying device, a second silica gel drying device, a first molecular sieve drying device, a second molecular sieve drying device, and a phosphorus pentoxide drying device. The protective atmosphere in the hydrogen generator passes through the first heating device to heat it so that the residual oxygen reacts with hydrogen to form water, and then successively passes through the first silica gel drying device and the first molecular sieve drying device for oxygen reduction and dehumidification. Then it enters the second heating device to make the residual oxygen react with hydrogen to form water again, and then successively passes through the second silica gel drying device, the second molecular sieve drying device, and the phosphorus pentoxide drying device for dehumidification. Then it enters the third heating device for three times of heating so that the residual oxygen or water molecules further react with graphite particles to form carbon monoxide to achieve the purpose of further oxygen reduction and dehumidification.

2. The preparation method of a corrosion-resistant iron-aluminum alloy according to claim 1, characterized in that, The specific operation of the second-step deflation is as follows: The inside of the furnace body is pumped to a low vacuum of 10 -1 Pa, high-purity argon gas is introduced, and the gas washing operation is repeated more than 5 times to minimize the oxygen concentration. Then it is pumped to a high vacuum environment of 10 -4 Pa to exhaust all the oxygen in the melting furnace. Finally, argon gas is introduced until the atmospheric pressure is balanced, so that the whole melting process is under the protection of argon gas environment.

3. The preparation method of an anti-corrosion iron-aluminum alloy according to claim 1, characterized in that In Step 3, when melting the mixed material, each sample is melted 2-4 times on each side, and each time is 30 s - 1 min.

4. The preparation method of an anti-corrosion iron-aluminum alloy according to claim 1, characterized in that, In Step 4, the alloy product is mechanically polished with sandpaper of 400 - 7000 mesh in sequence; the electrolyte used for polishing is a mixed solution of perchloric acid and acetic acid. A Zhaoxin constant current source is adopted, the output current is 0.5 - 2 A, the voltage is 3 - 5 V. The FeAlSi alloy sample is placed at the anode, and iron sheets are placed on the left and right sides as cathodes. A preset current is passed through, and the polishing time is 1 - 2 min.

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