Modification method for improving oxidation resistance of high-entropy alloy

Abstract

The invention discloses a modification method for improving oxidation resistance of a high-entropy alloy. The modification method comprises the following steps: S1, carrying out solution treatment and oil cooling on an as-cast high-entropy alloy; s2, the high-entropy alloy subjected to oil cooling is cut, surface oxide skin is removed, and a metal sample is obtained; and S3, the metal sample is subjected to large-deformation cold rolling treatment. According to the method, dendritic structures in the as-cast alloy are eliminated through solution treatment, then the solid-solution-state high-entropy alloy is subjected to multi-pass rolling, the total deformation is 60%-90%, and the oxidation resistance of the high-entropy alloy can be greatly improved. The method is reasonable in design and easy to operate, and the oxidation resistance of the high-entropy alloy is well improved.

Description

Technical Field

[0001] This invention relates to the field of high-temperature metal materials technology, and more specifically to a modification method for improving the oxidation resistance of high-entropy alloys. Technical Background

[0002] With the rapid development of various fields, the performance requirements for high-temperature resistant metal materials are becoming increasingly stringent, prompting continuous progress in the new high-temperature alloy industry in recent years. The concept of high-entropy alloys has provided extremely broad ideas for metal material design. High-entropy alloys are solid solution phases composed of five or more main elements, with each element's content ranging from 5% to 35%. High-entropy alloys have simple and stable structures, mostly consisting of FCC and BCC phases. High-entropy alloys possess superior properties unmatched by traditional metal materials. Due to their four major effects, high-entropy alloys easily yield thermally stable solid solution phases and nanostructures, giving them excellent phase stability at high temperatures. Therefore, high-entropy alloys show great potential in high-temperature applications.

[0003] In recent years, significant progress has been made in the research of high-entropy alloys. A large number of publications have focused on the development of novel alloy systems or on improving the oxidation resistance of existing high-entropy alloy systems through methods such as deformation heat treatment. The unique multi-principal-equal atomic ratio composition of high-entropy alloys leads to competitive oxidation of elements during oxidation, often forming complex and diverse oxide phases. These oxide phases typically lack continuity and protection.

[0004] Therefore, there is an urgent need for a modification method to improve the oxidation resistance of high-entropy alloys, so as to make them suitable for high-temperature fields such as aerospace. Summary of the Invention

[0005] The present invention aims to at least solve one of the technical problems existing in the prior art, and to provide a new technical solution for a modification method to improve the oxidation resistance of high-entropy alloys.

[0006] To achieve the above-mentioned objectives, the technical solution provided by this invention is as follows:

[0007] In one aspect, this invention provides a modification method for improving the oxidation resistance of high-entropy alloys, comprising the following steps:

[0008] S1. The as-cast high-entropy alloy is solution-treated and oil-cooled; the atomic percentage composition of the high-entropy alloy is: Al: 3.0-10.0%, Co: 12.0-17.0%, Cr: 5.0-17.0%, Cu: 4.0-12.0%, Fe: 28.0-35.0%, Ni: 24.5-30.5%, Ti: 0.1-5.0%.

[0009] S2. Cut the oil-cooled solid high-entropy alloy and remove the surface oxide layer to obtain a metal sample.

[0010] S3. The metal sample is subjected to multi-pass rolling at room temperature.

[0011] In step S1, the solution treatment temperature is 900–1200°C.

[0012] In step S1, the solution treatment time is 20 to 26 hours.

[0013] In step S1, the cooling method for the solution treatment is vegetable oil cooling.

[0014] In step S2, the thickness of the high-entropy alloy after cutting is 5mm to 10mm, and the length and width are both 10mm to 30mm.

[0015] In step S3, the rolling equipment for the metal sample is a 180 experimental rolling mill with a two-roll speed of 1.5 r / min.

[0016] In step S3, the rolling of the metal sample is carried out at room temperature.

[0017] In step S3, the speed of the two rollers remains unchanged, and the rolling rate is consistent with the previous rolling rate.

[0018] In step S3, the total number of rolling passes is 1 to 10.

[0019] In step S3, the single rolling reduction rate is 5% to 30%.

[0020] In step S3, the total reduction rate is 60%–90%.

[0021] Prior to step S1, the method further includes:

[0022] The high-purity elemental raw materials are placed in a melting furnace according to the specified ratio and then melted and cast to obtain the high-entropy alloy.

[0023] This invention modifies high-entropy alloys, and experimental results show that under the same oxidation conditions, it exhibits a significant improvement in oxidation resistance, which has important engineering application value in practical high-temperature applications.

[0024] The advantages and beneficial effects of this invention are as follows:

[0025] 1. This invention is based on the principle of heat treatment, which involves solution treatment of cast high-entropy alloys to eliminate dendritic structures and oxygen atom diffusion channels.

[0026] 2. The metal sample is subjected to multiple cold rolling processes to refine the grains, thereby effectively improving the oxidation resistance of the high-entropy alloy.

[0027] 3. The modification method described in this invention has simple equipment operation, low cost, safe operating environment, and can realize mass production. Attached Figure Description

[0028] Figure 1 This is a continuous oxidation curve of the as-cast high-entropy alloy in Example 1 at a high temperature of 800℃;

[0029] Figure 2 This is a SEM image of the surface morphology of the as-cast high-entropy alloy of Example 1 after high-temperature oxidation at 800℃;

[0030] Figure 3 This is a SEM image of the cross-sectional morphology of the as-cast high-entropy alloy of Example 1 after high-temperature oxidation at 800℃;

[0031] Figure 4 The image shows the EDS elemental distribution of the cross-sectional oxidation products of the as-cast high-entropy alloy after oxidation at 800℃ in Example 1.

[0032] Figure 5 This is a continuous oxidation curve of the solid solution high-entropy alloy in Example 2 at a high temperature of 800℃;

[0033] Figure 6 This is a SEM image of the surface morphology of the solid solution high-entropy alloy of Example 2 after high-temperature oxidation at 800℃;

[0034] Figure 7 This is a SEM image of the cross-sectional morphology of the solid solution high-entropy alloy of Example 2 after high-temperature oxidation at 800℃;

[0035] Figure 8 The image shows the EDS elemental distribution of the cross-sectional oxidation products of the solid solution high-entropy alloy after high-temperature oxidation at 800℃ in Example 2.

[0036] Figure 9 This is a continuous oxidation curve of the rolled high-entropy alloy in Example 3 at a high temperature of 800℃;

[0037] Figure 10 This is a SEM image of the surface morphology of the rolled high-entropy alloy of Example 3 after high-temperature oxidation at 800℃;

[0038] Figure 11 This is a SEM image of the cross-sectional morphology of the rolled high-entropy alloy of Example 3 after high-temperature oxidation at 800℃;

[0039] Figure 12 The image shows the EDS elemental distribution of the cross-sectional oxidation products of the rolled and cast high-entropy alloy in Example 3 after high-temperature oxidation at 800℃.

[0040] Figure 13The XRD patterns of the oxide films of high-entropy alloys in different states after oxidation at 800°C are shown in the examples. Detailed Implementation

[0041] To make the invention more apparent and understandable, preferred embodiments are described in detail below with reference to the accompanying drawings.

[0042] The present invention describes a modification method for improving the oxidation resistance of high-entropy alloys. In the embodiments, high-entropy alloys in three states—cast, solution-treated, and rolled—were subjected to high-temperature oxidation tests to better compare the improvement in their oxidation resistance.

[0043] The modification method for improving the oxidation resistance of high-entropy alloys in this invention includes the following steps:

[0044] (1) Charging: According to the designed composition, the required high-purity elemental raw materials are placed into the furnace mold of the smelting furnace. This process should strictly follow the material ratio to ensure that the sample composition is consistent with the design;

[0045] (2) Melting: After placing the materials to be melted, close and inspect the furnace body to ensure it is sealed. Then, draw a vacuum and begin alloy melting. During the melting process, the alloy ingot is turned over and melted 5 times to ensure uniform composition.

[0046] (3) Casting: After melting, the sample can be cast directly under vacuum conditions in the furnace. After casting, the sample is allowed to cool naturally before being taken to obtain a cast high-entropy alloy;

[0047] (4) Sample pretreatment: Heat the metal sample to 900-1200℃ for solid solution treatment for 20-26h, cut the sample into rectangular blocks with a length and width of 10mm-20mm and a thickness of 10mm-30mm, grind the cut sample to remove the surface oxide layer, and a solid solution high entropy alloy can be obtained.

[0048] (5) Sample rolling: The processed samples are rolled with small deformations at different reduction rates of 5% to 30%. The rolling equipment is a 180 experimental rolling mill with a maximum rolling pressure of 700 kN.

[0049] Example 1:

[0050] A modification method for improving the oxidation resistance of high-entropy alloys is as follows:

[0051] Step 1: Weigh the high-purity elemental raw materials precisely according to the proportion, and weigh out a clean raw material with a total mass of 500.00±0.02g;

[0052] Step 2: Place the cleaned high-purity metal raw material into the working station inside the electric arc melting furnace, and evacuate the vacuum to less than 6.0 × 10⁻⁶. -4Pa, stop evacuating, and fill the vacuum chamber with high-purity argon gas with a purity of 99.999%;

[0053] Step 3: Then begin alloy smelting. Place the alloys into the workstations of the smelting furnace. During the smelting process, the alloy ingots are turned over and smelted 5 times to ensure uniform composition.

[0054] Step 4: After melting is complete, pour the melted alloy into a mold to obtain a high-entropy alloy casting plate, and remove it after cooling to room temperature.

[0055] The mass of the as-cast high-entropy alloy increased to 1.2621 mg / cm³ after continuous oxidation at 800℃ for 100 h. 2 ,like Figure 1 As shown. Meanwhile, as Figure 2 , 3 As shown, the oxide film of the as-cast high-entropy alloy is relatively dense and thick. Figure 4 The EDS elemental distribution results of the cross-sectional oxide film show that after high-temperature oxidation at 800℃, the as-cast high-entropy alloy can form a typical double-layer oxide structure, resulting in a continuous and dense inner oxide film enriched in Al and Cr elements, while O elements are mostly enriched in the surface layer. Combined with... Figure 13 XRD diffraction analysis revealed that the oxide film formed by the as-cast high-entropy alloy was mainly composed of Fe-rich spinel oxide and Al2O3.

[0056] Example 2:

[0057] A modification method for improving the oxidation resistance of high-entropy alloys is as follows:

[0058] Step 1: Weigh the high-purity elemental raw materials precisely according to the proportion, and weigh out a clean raw material with a total mass of 500.00±0.02g;

[0059] Step 2: Place the cleaned high-purity metal raw material into the working station inside the electric arc melting furnace, and evacuate the vacuum to less than 6.0 × 10⁻⁶. -4 Pa, stop evacuating, and fill the vacuum chamber with high-purity argon gas with a purity of 99.999%;

[0060] Step 3: Then begin alloy smelting. Place the alloys into the workstations of the smelting furnace. During the smelting process, the alloy ingots are turned over and smelted 5 times to ensure uniform composition.

[0061] Step 4: After melting is complete, pour the melted alloy into a mold to obtain a high-entropy alloy casting plate, and remove it after cooling to room temperature.

[0062] Step 5: The cast plate is solution treated at 900-1200℃ for 20-26 hours and then oil cooled.

[0063] The obtained solid solution high-entropy alloy increased in mass to 2.0029 mg / cm³ after continuous oxidation at 800℃ for 100 h. 2 ,like Figure 5 As shown. Meanwhile, as Figure 6 , 7 As shown, the oxide film of the solid-solution high-entropy alloy is uniform and dense, but relatively thick. From... Figure 8 The EDS elemental distribution results of the cross-sectional oxide film show that, even after oxidation at 800℃, the solid solution-state high-entropy alloy oxide film still exhibits elemental stratification. Combined with... Figure 13 XRD diffraction analysis revealed that the oxide film formed by the solid solution high entropy alloy after oxidation at 800℃ is mainly composed of Fe3O4.

[0064] Example 3:

[0065] A modification method for improving the oxidation resistance of high-entropy alloys is as follows:

[0066] Step 1: Weigh the high-purity elemental raw materials precisely according to the proportion, and weigh out a clean raw material with a total mass of 500.00±0.02g;

[0067] Step 2: Place the cleaned high-purity metal raw material into the working station inside the electric arc melting furnace, and evacuate the vacuum to less than 6.0 × 10⁻⁶. -4 Pa, stop evacuating, and fill the vacuum chamber with high-purity argon gas with a purity of 99.999%;

[0068] Step 3: Then begin alloy smelting. Place the alloys into the workstations of the smelting furnace. During the smelting process, the alloy ingots are turned over and smelted 5 times to ensure uniform composition.

[0069] Step 4: After melting is complete, pour the melted alloy into a mold to obtain a high-entropy alloy casting plate, and remove it after cooling to room temperature.

[0070] Step 5: The cast plate is solution treated at 900-1200℃ for 20-26 hours and then oil cooled.

[0071] Step 6: Perform multi-pass rolling on the solution-treated sheet at room temperature, with a single rolling reduction of 5%–30% and a total reduction of 60%–90%.

[0072] The mass of the rolled high-entropy alloy increased by 0.1875 mg / cm³ after continuous oxidation at 800℃ for 100 h. 2 ,like Figure 9 As shown. Meanwhile, as Figure 10 , 11 As shown, the oxide film of this high-entropy alloy is uniform and dense in thickness, and the oxide film is thin, indicating excellent oxidation resistance. From... Figure 12 The EDS elemental distribution results of the cross-sectional oxide film show that after high-temperature oxidation at 800℃, the high-entropy alloy oxide film of this invention is dominated by Al, forming a continuous and dense oxide film enriched in Al, which effectively prevents the continuous inward diffusion of O atoms. Combined with... Figure 13 XRD diffraction pattern analysis shows that the oxide film formed by the high entropy alloy after oxidation at 800℃ is mainly composed of Al2O3.

[0073] In summary, this invention significantly improves the oxidation resistance of high-entropy alloys through solution treatment and rolling. After high-temperature oxidation, the rolled high-entropy alloy forms a continuous and dense protective oxide film, primarily composed of dense Al₂O₃, which inhibits the diffusion of O atoms and metal elements. The continuous oxidation weight gain of the cast high-entropy alloy within 100 hours is 1.2621 mg / cm³. 2 The continuous weight gain of the solid solution high-entropy alloy within 100 hours of oxidation was 2.0029 mg / cm³. 2 The continuous weight gain of the rolled high-entropy alloy within 100 hours of oxidation was 0.1875 mg / cm³. 2 In the embodiments of this application, the modified method for improving the oxidation resistance of high-entropy alloys produces rolled high-entropy alloys with significantly improved oxidation resistance, making them suitable for high-temperature applications such as aerospace and offering excellent benefits for industrial mass production.

Claims

1. A modification method for improving the oxidation resistance of high-entropy alloys, characterized in that, Includes the following steps: S1. The high-entropy alloy is subjected to solution treatment and oil cooling. The atomic percentage composition of the high-entropy alloy is: Al: 3.0-10.0%, Co: 12.0-17.0%, Cr: 5.0-17.0%, Cu: 4.0-12.0%, Fe: 28.0-35.0%, Ni: 24.5-30.5%, Ti: 0.1-5.0%. S2. Cut the oil-cooled solid high-entropy alloy and remove the surface oxide layer to obtain a metal sample; S3. The metal sample is subjected to multi-pass rolling at room temperature.

2. The modification method for improving the oxidation resistance of high-entropy alloys according to claim 1, characterized in that, The solution treatment temperature in step S1 is 900-1200℃, the solution treatment time is 20-26h, and the cooling method is vegetable oil cooling.

3. The modification method for improving the oxidation resistance of high-entropy alloys according to claim 1, characterized in that, In step S2, the thickness of the solid solution high entropy alloy after cutting is 5mm to 10mm, and the length and width of the solid solution high entropy alloy after cutting are both 10mm to 30mm.

4. The modification method for improving the oxidation resistance of high-entropy alloys according to claim 1, characterized in that, The rolling equipment for the metal sample in step S3 is a 180 experimental rolling mill with a two-roll speed of 1.5 r / min.

5. The modification method for improving the oxidation resistance of high-entropy alloys according to claim 1, characterized in that, In step S3, the metal sample is rolled at room temperature. The speed of the two rolls remains constant, the rolling rate is consistent with the previous rolling rate, the total number of rolling passes is 1 to 10, the single rolling reduction rate is 5% to 30%, and the total reduction rate is 60% to 90%.

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