High-entropy alloy with high mechanical property and high corrosion resistance and preparation method thereof

Abstract

The invention relates to the technical field of high-entropy alloys, and discloses a high-entropy alloy with high mechanical property and high corrosion resistance and a preparation method thereof, the high-entropy alloy comprises Fe, Cr, Ni, Al and Si, the atomic ratio of Fe to Cr to Ni to Al to Si is 2: x: 1: 0.2: 0.3, and x is more than or equal to 1.22 and less than or equal to 1.26. Elementary substances corresponding to corresponding elements in the high-entropy alloy are used as raw materials, and the high-entropy alloy is obtained through smelting. The high-entropy alloy has excellent mechanical properties and corrosion resistance and is low in cost, no expensive Co element is added, Fe and Cr elements with relatively low cost are added, and the production cost is reduced.

Description

Technical Field

[0001] The present invention relates to the technical field of high entropy alloys, and in particular to a high entropy alloy with high mechanical properties and high corrosion resistance and a preparation method thereof. Background Art

[0002] High-entropy alloys (HEAs), as an emerging class of alloy materials, feature multiple principal elements and complex compositions. They possess unique properties such as high entropy effect, lattice distortion effect, diffusion hysteresis effect, and cocktail effect. They exhibit excellent overall performance, including superior mechanical properties and corrosion resistance, and hold broad application prospects in aerospace, energy, automotive, and other fields. However, most conventional HEAs, such as CoCrFeNiAl, contain the expensive element Co, which limits their large-scale engineering applications.

[0003] In recent years, researchers have been committed to developing Co-free or low-Co high-entropy alloy systems to reduce costs and expand their applications. At the same time, the comprehensive performance of existing high-entropy alloys in terms of mechanical properties and corrosion resistance remains a hot topic of research, with significant room for optimization.

[0004] However, there are still some problems, such as the small improvement in mechanical properties and corrosion resistance, complex processing technology and high production costs.

[0005] Therefore, there is an urgent need for a high entropy alloy with high mechanical properties and high corrosion resistance and a preparation method thereof to solve the above technical problems. Summary of the Invention

[0006] The purpose of the present invention is to overcome the existing technical problems and provide a high entropy alloy with high mechanical properties and high corrosion resistance and a preparation method thereof.

[0007] To achieve the above object, the present invention is implemented according to the following technical solutions:

[0008] A high-entropy alloy with high mechanical properties and high corrosion resistance, the high-entropy alloy comprising Fe, Cr, Ni, Al, and Si, wherein the atomic ratio of Fe, Cr, Ni, Al, and Si is 2:x:1:0.2:0.3, wherein 1.22≤x≤1.26.

[0009] The high entropy alloy of the present invention is simply represented by Fe2Cr according to the chemical formula and atomic ratio. x NiAl 0.2 Si 0.3 The high entropy alloy of the present invention has a heterogeneous microstructure, including an FCC phase and a BCC phase.

[0010] A method for preparing a high-entropy alloy with high mechanical properties and high corrosion resistance, using simple substances corresponding to corresponding elements in the high-entropy alloy as raw materials, and obtaining the high-entropy alloy through smelting.

[0011] Preferably, the purity of Fe, Cr, Ni, Al and Si is greater than 99.9%.

[0012] Preferably, the smelting is carried out in a vacuum arc furnace.

[0013] Preferably, the smelting environment is an ultra-low pressure vacuum and is filled with argon.

[0014] Preferably, the preparation method comprises the following steps:

[0015] S1, weigh the corresponding metal elements as raw materials according to the atomic ratio of Fe, Cr, Ni, Al, and Si of 2:x:1:0.2:0.3, where 1.22≤x≤1.26;

[0016] S2, placing the raw materials weighed in step S1 into a vacuum arc furnace and melting them in an ultra-low pressure vacuum atmosphere filled with argon; using an electromagnetic stirring device during the melting process, and repeating the melting multiple times; after the melting is completed, cooling with the furnace to obtain the desired high entropy alloy.

[0017] Preferably, in step S2, the smelting temperature is 2500° C. and the smelting time is 5 minutes.

[0018] The present invention aims to provide a high iron-chromium heterostructure high-entropy alloy with high mechanical properties and high corrosion resistance. By regulating the atomic ratio of the Cr element, a high-entropy alloy with excellent performance is obtained without adding the expensive Co element and without complicated processing steps.

[0019] The high entropy alloy of the present invention is a high iron-chromium heterostructure high entropy alloy with high mechanical properties and high corrosion resistance, which is abbreviated as Fe2Cr according to the chemical formula and atomic ratio. x NiAl 0.2 Si 0.3 , where x ranges from 1.22 to 1.26. This high-entropy alloy is prepared by melting in a vacuum arc furnace. Repeated melting and casting processes produce a heterogeneous microstructure consisting of FCC and BCC phases. By adjusting the Cr content, the ratio of FCC to BCC phases in the alloy can be varied, thereby optimizing the alloy's mechanical properties and corrosion resistance.

[0020] Among the many high entropy alloy systems, the high iron-chromium cobalt-free heterostructure high entropy alloy Fe2Cr x NiAl 0.2 Si 0.3(x = 1.22 to 1.26) exhibits unique advantages. Its compositional design is ingenious. Under the dominance of Fe and Cr, adjusting the Cr content optimizes the alloy's phase structure and properties, enhancing its mechanical properties and corrosion resistance, allowing it to maintain good performance in a variety of environments. Furthermore, this alloy is formed by casting, eliminating the need for complex processing, saving time and energy, and reducing production costs, offering new insights into the development of cost-effective high-entropy alloys.

[0021] Beneficial effects:

[0022] 1. High entropy alloy Fe2Cr of the present invention x NiAl 0.2 Si 0.3 It has excellent mechanical properties and corrosion resistance. When x=1.24, the ultimate tensile strength of the high-entropy alloy reaches 1160MPa, and the tensile plasticity is close to 6%. The corrosion resistance of the high-entropy alloy of the present invention has exceeded that of 304 stainless steel, among which x=1.24 and x=1.26 have the best corrosion resistance; a dense passivation film can be formed on the alloy surface, which effectively improves the corrosion resistance.

[0023] 2. High entropy alloy Fe2Cr of the present invention x NiAl 0.2 Si 0.3 The cost is low, and the expensive Co element is not added, but the relatively low-cost Fe and Cr elements are added, thereby reducing the production cost.

[0024] 3. High entropy alloy Fe2Cr of the present invention x NiAl 0.2 Si 0.3 The process is simple and good performance can be obtained in the cast state without the need for complicated processing procedures, saving time and energy. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] Figure 1 XRD patterns of the high entropy alloys obtained in Example 1, Example 2, and Example 3 of the present invention;

[0026] Figure 2 The SEM backscatter images of the high entropy alloys obtained in Examples 1, 2, and 3 of the present invention are as follows;

[0027] Figure 3 Graphs showing typical tensile stress-strain curves of high entropy alloys obtained in Examples 1, 2, and 3 of the present invention;

[0028] Figure 4 These are Tafel plots of the high entropy alloys obtained in Examples 1, 2, and 3 of the present invention. DETAILED DESCRIPTION

[0029] The present invention will be further described in detail below with reference to specific embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not intended to limit the present invention.

[0030] There is no particular limitation on the purity of all raw materials in the present invention. The present invention preferably uses industrial purity or conventional purity used in the art.

[0031] The devices used in the present invention are not particularly limited and can be devices commonly used in the art.

[0032] Example 1:

[0033] A high entropy alloy with high mechanical properties and high corrosion resistance, the high entropy alloy comprising Fe, Cr, Ni, Al, and Si, wherein the atomic ratio of Fe, Cr, Ni, Al, and Si is 2:1.22:1:0.2:0.3, and the chemical formula is abbreviated as Fe2Cr according to the atomic ratio. 1.22 NiAl 0.2 Si 0.3 .

[0034] A method for preparing a high-entropy alloy with high mechanical properties and high corrosion resistance comprises the following steps:

[0035] S1, raw material preparation and proportion: select Fe, Cr, Ni, Al, Si metal raw materials with purity greater than 99.9%, according to Fe2Cr 1.22 NiAl 0.2 Si 0.3 The composition ratio is accurately proportioned, the mass of each raw material is calculated to ensure that the ratio is accurate, and a total of 40g of metal raw materials are weighed as raw materials for preparing high entropy alloys.

[0036] S2, smelting process: 40g of high entropy alloy raw materials and a high-purity titanium ingot were placed in different crucibles in the vacuum arc furnace. After placing the raw materials, the furnace door was closed and vacuum was started using a mechanical pump and a molecular pump. When the pressure in the furnace was lower than 3×10 -3 Pa, stop vacuuming, and then introduce high-purity argon into the furnace to make the pressure in the furnace chamber reach 0.05MPa; before smelting, the air tightness of the device must be checked by melting titanium ingots. Only when the air tightness is good can the alloy be smelted; an electromagnetic stirring device is used during smelting to homogenize the alloy; the alloy needs to be smelted five times, each smelting temperature is 2500℃, and the duration is 5min. After each smelting, the alloy ingot should be turned over to ensure a more uniform smelting effect;

[0037] Finally, the required Fe2Cr is obtained 1.22 NiAl 0.2 Si 0.3 Alloy ingots.

[0038] Sample processing:

[0039] The samples of the required size were cut from the obtained alloy ingot by wire cutting process, and one part was processed into the size of 3×6×8mm. 3 The block specimens were used for subsequent corrosion performance tests and microstructure characterization; the other part was processed into dog-bone tensile specimens with a gauge length of 10 mm, a width of 2 mm, and a thickness of 1.5 mm for mechanical performance tests.

[0040] Performance:

[0041] Mechanical properties: such as Figure 3 As shown, the ultimate tensile strength of the high-entropy alloy of this example reaches 1026 MPa, and the tensile plasticity is approximately 11%. The tensile stress-strain curve exhibits a typical dimple-shaped fracture morphology, indicating the alloy's good toughness. This is due to the synergistic effect of the FCC and BCC phases within the alloy. The plasticity of the FCC phase complements the strengthening effect of the BCC phase, enabling the alloy to maintain a certain degree of plastic deformation capacity even when subjected to high tensile stress.

[0042] Corrosion resistance: Figure 4 As shown, the high entropy alloy of this embodiment was electrochemically tested in a 3.5wt.% NaCl solution, and its self-corrosion potential was -0.134V and the corrosion current density was 8.687×10 -8 A / cm 2 , with a pitting potential of 0.453 V. Compared to 304 stainless steel, its corrosion resistance is significantly improved. This is because the high Cr content in the alloy forms a dense Cr2O3 oxide film on the surface, which effectively blocks chloride ion corrosion and improves the alloy's corrosion resistance.

[0043] Example 2

[0044] A high entropy alloy with high mechanical properties and high corrosion resistance, the high entropy alloy comprising Fe, Cr, Ni, Al, and Si, wherein the atomic ratio of Fe, Cr, Ni, Al, and Si is 2:1.24:1:0.2:0.3, and the chemical formula is abbreviated as Fe2Cr according to the atomic ratio. 1.24 NiAl 0.2 Si 0.3 .

[0045] A method for preparing a high entropy alloy with high mechanical properties and high corrosion resistance, the specific steps are the same as in Example 1, and finally Fe2Cr 1.24 NiAl 0.2 Si 0.3 Alloy ingots.

[0046] Sample processing:

[0047] The alloy ingots were processed into block specimens and tensile specimens of the same standard size as in Example 1.

[0048] Performance:

[0049] Mechanical properties: such as Figure 3 As shown, the ultimate tensile strength of the high-entropy alloy of this example reaches 1160 MPa, and the tensile plasticity is close to 6%. Its tensile stress-strain curve shows that the alloy achieves high strength while still maintaining a certain degree of plasticity. This is due to the optimization of the alloy's internal heterogeneous structure, which has a more rational distribution of FCC and BCC phases and enhanced synergy between the phases. This effectively hinders dislocation movement when the alloy is subjected to tensile stress, thereby improving strength while also retaining a certain degree of plasticity.

[0050] Corrosion resistance: Figure 4 As shown, the high entropy alloy of this embodiment was tested in the same 3.5wt.% NaCl solution, and its self-corrosion potential was -0.118V and the corrosion current density was 1.743×10 -7 A / cm 2 , the pitting potential is 0.721 V. Among the three alloys, its corrosion resistance is the best, which is mainly attributed to the further increase of Cr element content, which makes the passivation film on the alloy surface denser and more resistant to chloride ions, thereby effectively delaying the occurrence of corrosion.

[0051] Example 3

[0052] A high entropy alloy with high mechanical properties and high corrosion resistance, the high entropy alloy comprising Fe, Cr, Ni, Al, and Si, wherein the atomic ratio of Fe, Cr, Ni, Al, and Si is 2:1.26:1:0.2:0.3, and the chemical formula is abbreviated as Fe2Cr according to the atomic ratio 1.26 NiAl 0.2 Si 0.3 .

[0053] A method for preparing a high entropy alloy with high mechanical properties and high corrosion resistance, the specific steps are the same as in Example 1, and finally Fe2Cr 1.26 NiAl 0.2 Si 0.3 Alloy ingots.

[0054] Sample processing: The alloy ingots were processed into block specimens and tensile specimens of the same standard size as in Example 1.

[0055] Performance:

[0056] Mechanical properties: such as Figure 3As shown, the ultimate tensile strength of the high entropy alloy of this embodiment is 1115MPa; the tensile plasticity is about 3%. Although its strength is slightly lower than that of Fe2Cr 1.24 NiAl 0.2 Si 0.3 The alloy still exhibits a high strength level. However, as the Cr content increases further, the BCC phase ratio increases, resulting in a decrease in the plasticity of the alloy.

[0057] Corrosion resistance: Figure 4 As shown in the electrochemical test results of the high entropy alloy of this embodiment in 3.5wt.% NaCl solution, its self-corrosion potential is -0.119V and the corrosion current density is 1.487×10 -7 A / cm 2 , the pitting potential is 0.726V. Its corrosion resistance is similar to that of Fe2Cr 1.24 NiAl 0.2 Si 0.3 Alloys are similar, both better than Fe2Cr 1.22 NiAl 0.2 Si 0.3 This shows that increasing the Cr content appropriately can help improve the corrosion resistance of the alloy, but excessive Cr may cause changes in the alloy microstructure, affecting the further improvement of its corrosion resistance.

[0058] like Figure 1 As shown, the XRD patterns of the high entropy alloys obtained in Examples 1, 2 and 3 of the present invention are shown; the curve corresponding to Cr1.22 in the figure is the curve corresponding to Fe2Cr prepared in Example 1. 1.22 NiAl 0.2 Si 0.3 , the curve corresponding to Cr1.24 is the Fe2Cr prepared in Example 2 1.24 NiAl 0.2 Si 0.3 The curve corresponding to Cr1.26 is the Fe2Cr prepared in Example 3. 1.26 NiAl 0.2 Si 0.3 .

[0059] like Figure 2 As shown, the SEM backscattered images of the high entropy alloys obtained in Example 1, Example 2, and Example 3 of the present invention are shown; Cr1.22 in (a), (b), and (c) represents the Fe2Cr prepared in Example 1. 1.22 NiAl 0.2 Si 0.3 ; Cr1.24 in Figure (d), (e), and (f) represents Fe2Cr prepared in Example 2 1.24NiAl 0.2 Si 0.3 ; Cr1.26 in Figure (g), (h), and (l) represents Fe2Cr prepared in Example 3 1.26 NiAl 0.2 Si 0.3 ;

[0060] like Figure 3 As shown in the figure, the typical tensile stress-strain curves of the high entropy alloys obtained in Examples 1, 2 and 3 of the present invention are shown; the curve corresponding to Cr1.22 in the figure is the curve corresponding to Fe2Cr prepared in Example 1. 1.22 NiAl 0.2 Si 0.3 , the curve corresponding to Cr1.24 is the Fe2Cr prepared in Example 2 1.24 NiAl 0.2 Si 0.3 The curve corresponding to Cr1.26 is the Fe2Cr prepared in Example 3. 1.26 NiAl 0.2 Si 0.3 .

[0061] like Figure 4 The following are Tafel plots of high entropy alloys obtained in Example 1, Example 2, and Example 3 of the present invention. The curve corresponding to Cr1.22 in the figure is the Fe2Cr prepared in Example 1. 1.22 NiAl 0.2 Si 0.3 , the curve corresponding to Cr1.24 is the Fe2Cr prepared in Example 2 1.24 NiAl 0.2 Si 0.3 The curve corresponding to Cr1.26 is the Fe2Cr prepared in Example 3. 1.26 NiAl 0.2 Si 0.3 .

[0062] The technical solution of the present invention is not limited to the above-mentioned specific embodiments. Any technical variations made according to the technical solution of the present invention fall within the protection scope of the present invention.

Claims

1. A high entropy alloy with high mechanical properties and high corrosion resistance, characterized by: The high entropy alloy comprises Fe, Cr, Ni, Al, and Si, wherein the atomic ratio of Fe, Cr, Ni, Al, and Si is 2:x:1:0.2:0.3, wherein 1.22≤x≤1.

26.

2. The method for preparing a high entropy alloy having high mechanical properties and high corrosion resistance according to claim 1, characterized in that: The high entropy alloy is obtained by smelting the single substances corresponding to the corresponding elements in the high entropy alloy as raw materials.

3. The method for preparing a high entropy alloy having high mechanical properties and high corrosion resistance according to claim 2, characterized in that: The purity of Fe, Cr, Ni, Al and Si is greater than 99.9%.

4. The method for preparing a high entropy alloy having high mechanical properties and high corrosion resistance according to claim 2, wherein: The smelting adopts a vacuum arc furnace.

5. The method for preparing a high entropy alloy having high mechanical properties and high corrosion resistance according to claim 2, wherein: The smelting environment is ultra-low pressure vacuum and filled with argon.

6. The method for preparing a high entropy alloy having high mechanical properties and high corrosion resistance according to claim 2, wherein: The following steps are involved: S1, weigh the corresponding metal elements as raw materials according to the atomic ratio of Fe, Cr, Ni, Al, and Si of 2:x:1:0.2:0.3, where 1.22≤x≤1.26; S2, placing the raw materials weighed in step S1 into a vacuum arc furnace and melting them in an ultra-low pressure vacuum atmosphere filled with argon; using an electromagnetic stirring device during the melting process, and repeating the melting multiple times; after the melting is completed, cooling with the furnace to obtain the desired high entropy alloy.

7. The method for preparing a high entropy alloy having high mechanical properties and high corrosion resistance according to claim 6, characterized in that: In step S2, the smelting temperature is 2500° C. and the smelting time is 5 minutes.

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