Quaternary medium-entropy alloy of FCC (fluid catalytic cracking) matrix and preparation method of quaternary medium-entropy alloy

Abstract

The invention discloses a quaternary medium-entropy alloy of an FCC (Fluid Catalytic Cracking) matrix and a preparation method of the quaternary medium-entropy alloy, the molecular formula of the quaternary medium-entropy alloy of the FCC matrix is Six (CrFeNi) 100-x, and x is equal to 0, 3, 6 or 9. By adding the Si element, the strength and plasticity of the alloy are remarkably improved, the preparation process is optimized, the production efficiency is improved, and the comprehensive performance of the alloy is improved. The preparation method saves raw materials, reduces cost, is environment-friendly and has a wide application prospect.

Description

Technical Field

[0001] This application relates to the field of metallic materials technology, and in particular to a quaternary medium-entropy alloy with an FCC matrix and its preparation method. Background Technology

[0002] Medium-entropy alloys are a new type of alloy material composed of three to four elements in equiatomic or near-equiatomic ratios. They possess excellent properties such as high strength, high hardness, good wear resistance, and corrosion resistance. However, the large number of alloying elements often leads to higher economic costs. Although most single-phase FCC-structured medium-entropy alloys exhibit excellent ductility and fracture toughness, their low room-temperature strength limits their application as structural materials.

[0003] Therefore, providing a medium-entropy alloy with a certain strength at room temperature has become a technical problem that urgently needs to be solved in this field. Summary of the Invention

[0004] To address the problems of existing technologies, this application provides a quaternary medium-entropy alloy with an FCC matrix and its preparation method. The technical solution is as follows: In a first aspect, a quaternary medium-entropy alloy with an FCC matrix is ​​provided, wherein the molecular formula of the quaternary medium-entropy alloy with the FCC matrix is ​​Si. x (CrFeNi) 100-x , where x = 0-9.

[0005] Furthermore, x is 0, 3, 6, or 9.

[0006] Secondly, a method for preparing a quaternary medium-entropy alloy with an FCC matrix is ​​provided, comprising the following steps: Pretreated Si, Cr, Fe and Ni are smelted under vacuum and argon protection to obtain an alloy liquid. The alloy liquid is cooled to form an alloy ingot. The alloy ingot is repeatedly smelted and cooled until the components in the alloy ingot are uniformly mixed.

[0007] Furthermore, the atomic percentages of Si, Cr, Fe and Ni are Si = (0-9)%, Cr + Fe + Ni = (91-100)%, and Cr: Fe: Ni = 1:1:1.

[0008] Furthermore, the atomic ratio of Si, Cr, Fe, and Ni is as follows: Si=0%, Cr+Fe+Ni=100%, and Cr:Fe:Ni=1:1:1; Si=3%, Cr+Fe+Ni=97%, and Cr:Fe:Ni=1:1:1; Si=6%, Cr+Fe+Ni=94%, and Cr:Fe:Ni=1:1:1; Si=9%, Cr+Fe+Ni=91%, and Cr:Fe:Ni=1:1:1.

[0009] Furthermore, the vacuum degree of the vacuum condition is 1.0 × 10⁻⁶. -3 MPa.

[0010] Furthermore, the alloy ingot is repeatedly melted and cooled 3-6 times until all components in the alloy ingot are evenly mixed.

[0011] Furthermore, the pretreatment method involves ultrasonically cleaning the Si, Cr, Fe, and Ni raw materials with ethanol for 15 minutes.

[0012] Furthermore, the smelting method is electric arc melting.

[0013] Furthermore, the molecular formula of the quaternary medium-entropy alloy of the FCC matrix is ​​Si. x (CrFeNi) 100-x , where x = 0-9.

[0014] The beneficial effects of the technical solution provided in this application are: the molecular formula of the quaternary medium-entropy alloy of the FCC matrix in this application is Si. x (CrFeNi) 100-x Where x = 0, 3, 6, or 9. This application significantly improves the strength and plasticity of the alloy by adding Si, optimizes the preparation process, increases production efficiency, and improves the overall performance of the alloy. The preparation method saves raw materials, reduces costs, is environmentally friendly, and has broad application prospects. Attached Figure Description

[0015] To more clearly illustrate the technical solutions in the embodiments of this application, the accompanying drawings used in the description of the embodiments will be briefly introduced below. Obviously, the accompanying drawings described below are only some embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0016] Figure 1 The Si prepared in the embodiments of this application x (CrFeNi) 100-x Room temperature quasi-static tensile stress-strain curves of medium-entropy alloys; Figure 2 The Si prepared in the embodiments of this application x (CrFeNi) 100-x Vickers hardness chart of medium-entropy alloys; Figure 3 The Si prepared in the embodiments of this application x (CrFeNi)100-x X-ray diffraction pattern of medium-entropy alloy; Figure 4 The Si prepared in the embodiments of this application x (CrFeNi) 100-x Optical micrograph of a medium-entropy alloy; Figure 5 The Si prepared in the embodiments of this application x (CrFeNi) 100-x Scanning micrograph of a medium-entropy alloy; Figure 6 The tensile fracture morphology of the CrFeNi medium-entropy alloy prepared in the embodiments of this application is shown. Figure 7 The Si prepared in the embodiments of this application x (CrFeNi) 100-x Tensile fracture morphology of medium-entropy alloys. Detailed Implementation

[0017] To make the objectives, technical solutions, and advantages of this application clearer, the embodiments of this application will be described in further detail below with reference to the accompanying drawings.

[0018] The main reasons why it is difficult to achieve both strength and plasticity in medium-entropy alloys are as follows: ① Limited solid solution strengthening: Traditional medium-entropy alloys mainly rely on solid solution strengthening to improve strength, but its effect is limited. ② Hindered dislocation movement: The complex chemical composition and multi-principal element effect of medium-entropy alloys hinder dislocation movement, thus causing a decrease in plasticity. ③ Lack of effective strengthening mechanisms: Traditional medium-entropy alloys lack effective strengthening mechanisms while improving both strength and plasticity.

[0019] To improve the strength of entropy alloys in single-phase FCC structures, solid solution strengthening and other mechanisms are typically employed. This application attempts to increase the Si element. Si atoms dissolved in the matrix cause lattice distortion, increasing the resistance to dislocation movement and improving the alloy's strength and hardness. Appropriate control of the Si content can optimize the alloy's phase structure, forming intermetallic compounds and enhancing overall performance. However, how to control the Si content to achieve a strong-ductility balance in a Si-containing FCC matrix remains a challenge.

[0020] (1) Ingredient design Adding Si: Si significantly improves the strength of the FCC matrix through multiple mechanisms, including solid solution strengthening, formation of nanoprecipitates, grain boundary strengthening, and enhanced work hardening ability. Its advantage lies in maintaining a certain level of plasticity and toughness while improving strength, as well as high-temperature performance and phase stability. Therefore, Si is an important alloying element for optimizing the alloy properties of the FCC matrix. In this application, the Si content is controlled between 0-9 at.%. Other elements: Cr, Fe, Ni, etc., as the main constituent elements of medium-entropy alloys, provide solid solution strengthening and ensure the stability of the alloy.

[0021] (2) Preparation process 2.1 SiO medium-entropy alloy Pretreatment: Place the Cr, Fe and Ni bulk raw materials in a beaker, add ethanol and ultrasonically clean for 15 min, then blow dry.

[0022] Smelting: Smelting is carried out using a DHL-400 high-vacuum non-consumable arc melting furnace. The arc melting temperature is extremely high, allowing for precise metal purification and flexible production of various high-quality alloys. Furthermore, it is environmentally friendly and efficient under vacuum conditions. Cleaned Cr, Fe, and Ni (all with a purity ≥ 99.99%) are added to the furnace in an atomic percentage ratio of Cr + Fe + Ni = 100%, with a Cr:Fe:Ni ratio of 1:1:1. The melting is carried out under a vacuum of 1.0 × 10⁻⁶. -3 Arc melting is performed under MPa and argon protection. After melting, the alloy is cooled to 200℃ to form an alloy ingot. The alloy ingot is melted and cooled repeatedly 3-6 times to ensure that the components in the alloy are mixed uniformly. Finally, it is melted again into a liquid alloy and poured into a 10×10×3mm... 3 In the dimensional mold, a cast SiO medium-entropy alloy plate is obtained.

[0023] 2.2 Si3 medium-entropy alloy Pretreatment: Place the bulk raw materials of Si, Cr, Fe and Ni in a beaker, add ethanol and ultrasonically clean for 15 min, and then blow dry.

[0024] Smelting: Smelting is carried out using a DHL-400 high-vacuum non-consumable arc melting furnace. The arc melting temperature is extremely high, allowing for precise metal purification and flexible production of various high-quality alloys. Furthermore, it is environmentally friendly and efficient under vacuum conditions. Cleaned Si, Cr, Fe, and Ni (all with a purity ≥ 99.99%) are added to the furnace in an atomic percentage ratio of Si = 3%, Cr + Fe + Ni = 97%, and Cr:Fe:Ni = 1:1:1. The process is carried out under a vacuum of 1.0 × 10⁻⁶. -3 Arc melting is performed under MPa and argon protection. After melting, the alloy is cooled to 200℃ to form an alloy ingot. The alloy ingot is melted and cooled repeatedly 3-6 times to ensure that the components in the alloy are mixed uniformly. Finally, it is melted again into a liquid alloy and poured into a 10×10×3mm...3 In the dimensional mold, a cast Si3 medium-entropy alloy plate is obtained.

[0025] 2.3 Si6 medium-entropy alloy Pretreatment: Place the bulk raw materials of Si, Cr, Fe and Ni in a beaker, add ethanol and ultrasonically clean for 15 min, and then blow dry.

[0026] Smelting: Smelting is carried out using a DHL-400 high-vacuum non-consumable arc melting furnace. The arc melting temperature is extremely high, allowing for precise metal purification and flexible production of various high-quality alloys. Furthermore, it is environmentally friendly and efficient under vacuum conditions. Cleaned Si, Cr, Fe, and Ni (all with a purity ≥ 99.99%) are added to the furnace at an atomic percentage of Si = 6%, Cr + Fe + Ni = 94%, and Cr:Fe:Ni = 1:1:1. The process is carried out under a vacuum of 1.0 × 10⁻⁶. -3 Arc melting is performed under MPa and argon protection. After melting, the alloy is cooled to 200℃ to form an alloy ingot. The alloy ingot is melted and cooled repeatedly 3-6 times to ensure that the components in the alloy are mixed uniformly. Finally, it is melted again into a liquid alloy and poured into a 10×10×3mm... 3 In the dimensional mold, a cast Si6 medium-entropy alloy plate is obtained.

[0027] 2.4 Si9 medium-entropy alloy Pretreatment: Place the bulk raw materials of Si, Cr, Fe and Ni in a beaker, add ethanol and ultrasonically clean for 15 min, and then blow dry.

[0028] Smelting: Smelting is carried out using a DHL-400 high-vacuum non-consumable arc melting furnace. The arc melting temperature is extremely high, allowing for precise metal purification and flexible production of various high-quality alloys. Furthermore, it is environmentally friendly and efficient under vacuum conditions. Cleaned Si, Cr, Fe, and Ni (all with a purity ≥ 99.99%) are added to the furnace with an atomic percentage of Si = 9%, Cr + Fe + Ni = 91%, and Cr:Fe:Ni = 1:1:1. The process is carried out under a vacuum of 1.0 × 10⁻⁶. -3 Arc melting is performed under MPa and argon protection. After melting, the alloy is cooled to 200℃ to form an alloy ingot. The alloy ingot is melted and cooled repeatedly 3-6 times to ensure that the components in the alloy are mixed uniformly. Finally, it is melted again into a liquid alloy and poured into a 10×10×3mm... 3 In the dimensional mold, a cast Si9 medium-entropy alloy plate is obtained.

[0029] (3) Sample testing The four types of as-cast plates of medium-entropy alloys were subjected to physicochemical tests, and the results are as follows: Figure 1-7 As shown.

[0030] The yield strength and tensile strength of four alloy plates were tested using a CMT4305 microcomputer-controlled universal testing machine. The results are as follows: Figure 1 As shown, the yield strength and tensile strength of the alloy gradually increase with the increase of Si content, rising from 172 MPa and 339 MPa for Si0 to 351 MPa and 505 MPa for Si9. However, with the change in Si content, the elongation after fracture first increases and then decreases, decreasing from 44.4% for Si0 to 16.8% for Si9. Overall, the Si6 alloy exhibits the best balance between strength and ductility.

[0031] The four alloy plates were tested using a Wilson VH1102 Vickers hardness tester. The results are as follows: Figure 2 As shown, Si x (CrFeNi) 100-x The hardness of the medium-entropy alloy gradually increases with increasing Si content. Specifically, from Si0 to Si3, the hardness value increases by 37.8 HV, an increase of 14.1%; from Si3 to Si6, the hardness value increases by 31.6 HV, an increase of 14.2%; and from Si6 to Si9, the hardness value increases by 31.6 HV, an increase of 23.0%. The alloy reaches its maximum hardness at Si9.

[0032] Figure 3 The results were obtained by testing four alloy plates using a SMARTLAB X-ray diffractometer (XRD). Figure 3 In the analysis, Si0, Si3, and Si6 alloys exhibit a single-phase FCC structure, while diffraction peaks of silicides were detected in the Si9 alloy, indicating a two-phase FCC + silicide structure. Based on Jade software analysis, it is inferred that the silicides in Si9 are most likely Ni3Si2.

[0033] Figure 4 The results are obtained by examining the three alloy plates using an optical microscope (OM, model DMI300M). Figure 4 In the images, (a) and (b) represent Si3, (c) and (d) represent Si6, and (e) and (f) represent Si9. The microstructure of the Si-containing alloys exhibits color contrast differences caused by phase structure or elemental distribution, with the darker areas displaying typical columnar dendritic structures. Furthermore, the dendritic morphology becomes increasingly clear with increasing Si content. XRD analysis reveals that the Si3 and Si6 alloys have a single-phase FCC structure; therefore, the dark phase (dendritic phase) and light phase (interdendritic phase) differ only in elemental composition. The Si9 alloy contains a small amount of silicides, but the quantity is too small to be observed.

[0034] Figure 5These are the test results of three alloy plates using a cold field emission scanning electron microscope (SEM, Merlin Compact, model JSM-6610LV). Figure 5 In the images, (a), (b), and (c) represent Si3, (d), (e), and (f) represent Si6, and (g), (h), and (i) represent Si9. The Si3 alloy, aside from pitting corrosion caused by the corrosive liquid, does not exhibit significant phase separation contrast, further confirming the single-phase FCC structure of the Si3 medium-entropy alloy. The Si6 alloy, besides pitting corrosion caused by the corrosive liquid, shows a tendency towards phase separation. The magnified SEM image of the area within the blue box further confirms the single-phase structure of the Si6 medium-entropy alloy. Combined with XRD structural analysis, the Si6 medium-entropy alloy is an FCC single-phase structure with relatively obvious phase structure contrast. The Si9 alloy exhibits significant phase separation contrast. Combined with XRD structural analysis, the Si9 medium-entropy alloy is an FCC + silicide two-phase structure with obvious phase structure contrast.

[0035] Figure 6 and Figure 7 The results are from a cold field emission scanning electron microscope (SEM, Merlin Compact, model JSM-6610LV). Figure 6 (a) and (b) are Si0. Figure 7 (a) and (b) are Si6, (c) and (d) are Si6, and (e) and (f) are Si9. The results show that all Si x (CrFeNi) 100-x Medium-entropy alloys all exhibited ductile fracture, with numerous dimples on the fracture surface. Longitudinal comparison showed that the dimple width gradually decreased with increasing Si content, indicating that the alloy's resistance to instability and its plasticity decreased with increasing Si content. The presence of cleavage steps in Si9 indicated that the material did not undergo sufficient plastic deformation during fracture, meaning it has low toughness and a tendency towards brittle fracture. Analysis suggests that the brittle fracture is due to the formation of silicides. Therefore, in existing Si-containing Si... x (CrFeNi) 100-x Among medium-entropy alloys, Si3 medium-entropy alloys have the best plasticity.

[0036] This application improves the work hardening ability of materials by adding silicon (Si) to enhance dislocation interactions. Si can form fine intermetallic compounds or silicides with other elements, and the precipitated phases can pin dislocations, hindering dislocation movement and thus increasing strength. The addition of Si can regulate the phase stability of the FCC matrix, suppressing the formation of other phases (such as BCC or σ phase) and preventing the generation of brittle phases. This invention achieves a good balance between strength and ductility by controlling the Si content to 6 at.%.

[0037] The vacuum arc melting process used in this application is a mature metal processing method that is simple to operate and easy to industrialize. Through reasonable composition design and process optimization, complex processing steps are avoided, thus improving production efficiency.

[0038] The quaternary medium-entropy alloy with an FCC matrix in this application exhibits excellent wear resistance and corrosion resistance: due to the multi-principal element effect of the medium-entropy alloy and the addition of Si, the alloy possesses superior wear resistance and corrosion resistance, making it suitable for engineering applications in harsh environments. The strengthening phase formed through aging treatment maintains stability at high temperatures, giving the alloy good high-temperature strength and creep resistance.

[0039] This application reduces the use of precious metals and lowers raw material costs by adding Si to a Co-free CrFeNi matrix. Through rational composition design and process optimization, material waste is reduced and resource utilization is improved.

[0040] The manufacturing process used does not require the use of harmful chemicals, reducing environmental pollution, energy consumption, and raw material usage, which aligns with the concepts of green manufacturing and sustainable development.

[0041] It is suitable for manufacturing high-temperature and high-strength components such as aircraft engine blades and rocket engine casings; wear-resistant components such as engine cylinder blocks and gearbox gears; corrosion-resistant components such as nuclear reactor structural materials and fuel cell bipolar plates; and other components such as medical devices and sports equipment.

[0042] The above are merely preferred embodiments of this application and are not intended to limit this application. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of this application should be included within the protection scope of this application.

Claims

1. A quaternary medium-entropy alloy of FCC matrix, characterized in that, The molecular formula of the quaternary medium-entropy alloy of the FCC matrix is Si x (CrFeNi) 100-x where x = 0-9.

2. The quaternary medium-entropy alloy of the FCC matrix according to claim 1, characterized in that, The x is 0, 3, 6 or 9.

3. A method of producing a quaternary medium-entropy alloy of FCC matrix, characterized in that, The method comprises the following steps: The pre-processed Si, Cr, Fe and Ni are smelted under vacuum and argon protection to obtain an alloy liquid, the alloy liquid is cooled to form an alloy ingot, and the alloy ingot is repeatedly smelted and cooled until the components in the alloy ingot are uniformly mixed.

4. The production method according to claim 3, characterized by, The atomic percentage of the Si, Cr, Fe and Ni is Si=(0-9)%, Cr+Fe+Ni=(91-100)%, and Cr:Fe:Ni=1:1:

1.

5. The preparation method according to claim 4, characterized in that, The atomic ratio of the Si, Cr, Fe and Ni is: Si=0%, Cr+Fe+Ni=100%, and Cr:Fe:Ni=1:1:1; Si=3%, Cr+Fe+Ni=97%, and Cr:Fe:Ni=1:1:1; Si=6%, Cr+Fe+Ni=94%, and Cr:Fe:Ni=1:1:1; Si=9%, Cr+Fe+Ni=91%, and Cr:Fe:Ni=1:1:

1.

6. The preparation method according to claim 3, characterized in that, The vacuum degree of the vacuum condition is 1.0 x 10 - 3 Mpa.

7. The preparation method according to claim 3, characterized in that, The alloy ingot is repeatedly smelted and cooled 3-6 times until the components in the alloy ingot are uniformly mixed.

8. The preparation method according to claim 3, characterized in that, The pre-processing method is to ultrasonically clean the Si, Cr, Fe and Ni raw materials with ethanol for 15 min.

9. The preparation method according to claim 3, characterized in that, The smelting method is arc smelting.

10. The preparation method according to claim 3, characterized in that, The molecular formula of the quaternary medium-entropy alloy of the FCC matrix is Si x (CrFeNi) 100-x where x = 0-9.

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