Low-cost high-toughness corrosion-resistant casting medium-entropy alloy

Abstract

The invention belongs to the technical field of metal materials, and relates to a low-cost high-toughness corrosion-resistant casting medium-entropy alloy, the chemical formula of the alloy is FexCrNiAl < 0.37 > Ti < 0.37 >, and the value range of x is 3-6. The material is prepared through the processes of burdening, smelting, remelting, cooling curing and the like. The medium-entropy alloy provided by the invention has higher strength and better plasticity, and can meet the use requirements under complex stress conditions. And the stainless steel has excellent corrosion resistance, can show corrosion resistance comparable with that of stainless steel, and is suitable for corrosive environments such as ocean and chemical engineering. In addition, a complicated heat treatment process is not needed for secondary treatment, so that the operation steps are simplified, and the cost is reduced. And on the premise of ensuring the performance, a large amount of Fe element with relatively low price is used, so that the raw material cost of the alloy is greatly reduced, and popularization and application in the industrial field are facilitated.

Description

Technical Field

[0001] The present invention belongs to the technical field of metal materials, and in particular relates to a low-cost, high-strength, tough, and corrosion-resistant casting medium-entropy alloy. Background Art

[0002] In modern industry, traditional steel, thanks to its widespread availability and mature manufacturing processes, has become one of the most widely used structural materials, occupying a crucial position in numerous industries, including machinery manufacturing, construction, and transportation. However, due to its inherent material properties, traditional steel struggles to achieve a perfect balance of strength, ductility, and corrosion resistance. In demanding environments, such as deep-sea high-pressure, high-temperature, and highly corrosive environments, traditional steel is unable to simultaneously meet the demands for high strength, high ductility, and excellent corrosion resistance, significantly limiting the development and innovation of related industries.

[0003] In recent years, high-entropy alloys (HEAs) have become a research hotspot in materials science due to their exceptional mechanical properties and corrosion resistance. Unlike traditional alloys, which are primarily composed of a single primary element, HEAs are composed of multiple primary elements in equimolar or near-equimolar ratios. Their unique compositional design equips them with exceptional overall performance and demonstrates significant potential for application in high-end fields such as aerospace and energy. However, HEAs typically contain multiple expensive rare metal elements, resulting in high raw material costs, a key obstacle to their large-scale industrial application.

[0004] Medium-entropy alloys (MEAs), as an emerging alloy material, have an elemental composition intermediate between high-entropy alloys and traditional alloys, combining some of the advantages of both and showing promising performance potential. However, research on MEAs is still in its developmental stages, particularly within a specific composition range, where research into composition design and performance optimization is insufficient. Existing technologies have yet to fully explore how to optimize the strength, ductility, and corrosion resistance of MEAs by rationally balancing the types and proportions of elements. Consequently, MEAs have not been effectively explored in their practical applications. Summary of the Invention

[0005] The purpose of the present invention is to develop a low-cost, high-strength, tough, and corrosion-resistant cast medium-entropy alloy, aiming to solve the problem that existing materials are difficult to strike a balance between high strength, high plasticity, and corrosion resistance, while reducing the raw material cost of the alloy. By designing a cast medium-entropy alloy with a specific composition range, it can significantly improve the corrosion resistance while maintaining good mechanical properties, and the cost is effectively controlled, making it suitable for a variety of industrial application scenarios.

[0006] To achieve the above object, the present invention is implemented according to the following technical solutions:

[0007] A low-cost, high-strength, tough, and corrosion-resistant casting medium-entropy alloy with the chemical formula Fe x CrNiAl 0.37 Ti 0.37 , where the value of x ranges from 3 to 6.

[0008] Preferably, the microstructure of the low-cost, high-strength, tough, and corrosion-resistant cast medium-entropy alloy consists of a dual phase of FCC and BCC.

[0009] Preferably, the low-cost, high-strength, tough, and corrosion-resistant cast medium-entropy alloy is prepared by the following steps:

[0010] S1, ingredients: according to the molar ratio of each element in the chemical formula of the low-cost, high-strength, tough, and corrosion-resistant cast medium-entropy alloy, respectively weigh the metal raw materials of Fe, Cr, Ni, Al, and Ti, and mix them to obtain a well-proportioned raw material;

[0011] S2, smelting: the raw materials with good proportions are smelted in an arc melting furnace under a high-purity argon protection environment;

[0012] S3, remelting: After the raw materials with the right proportions are completely melted and the composition is uniform, multiple remelting operations are performed to obtain an alloy melt;

[0013] S4, cooling and solidification: injecting the alloy melt into the preheated mold for cooling and solidification to obtain an alloy ingot.

[0014] Preferably, in step S1, the purity of the metal raw materials of Fe, Cr, Ni, Al and Ti is greater than 99.9%.

[0015] Preferably, in step S2, the purity of the argon in the high-purity argon protection environment is greater than 99.99%.

[0016] Preferably, in step S3, the remelting is performed at least 4 times.

[0017] Preferably, the yield strength of the low-cost, high-strength, tough, and corrosion-resistant cast medium-entropy alloy is above 656 MPa, the tensile strength is above 1088 MPa, and the plasticity is above 5.2%.

[0018] Preferably, the low-cost, high-strength, tough, and corrosion-resistant cast medium-entropy alloy is subjected to a potentiodynamic polarization test in a 3.5wt% NaCl aqueous solution with a saturated calomel electrode as a reference electrode and Pt as a counter electrode. The scanning potential range is from -0.8V to 1.4V, and the scanning rate is 1mV / s. Its pitting potential is not less than 0.15V, and its self-corrosion potential is not less than -0.26V.

[0019] The working principle of this invention: By adjusting the chemical composition of the alloy, a cast medium-entropy alloy is designed. This alloy utilizes the interactions between different elements and the characteristics of the phase structure to achieve comprehensive optimization of high strength, high plasticity, and corrosion resistance. In terms of mechanical properties, the synergistic effect of the FCC (face-centered cubic) and BCC (body-centered cubic) dual-phase structure is utilized to enhance the strength and plasticity of the alloy through heterogeneous deformation-induced (HDI) back stress strengthening and phase transformation-induced plasticity (TRIP) effects. In terms of corrosion resistance, the rational combination of alloying elements forms a stable passivation film, enhancing the alloy's corrosion resistance.

[0020] Beneficial effects of the present invention:

[0021] 1. Excellent mechanical properties: Compared with traditional steel materials, the medium entropy alloy of the present invention has higher strength and better plasticity. x CrNiAl 0.37 Ti 0.37 (x=3, 4, 5, 6) The yield strength reaches 982MPa, 923MPa, 732MPa, and 656MPa respectively, the tensile strength can reach 1231MPa, 1218MPa, 1088MPa, and 1134MPa respectively, and the plasticity can reach 5.2%, 8.0%, 14.7%, and 18.8% respectively, which can meet the use requirements under complex stress conditions.

[0022] 2. Outstanding corrosion resistance: In a 3.5wt% NaCl aqueous solution, the medium-entropy alloy of the present invention exhibits corrosion resistance comparable to that of stainless steel, has a high self-corrosion potential and a high pitting potential, can effectively resist localized corrosion forms such as pitting corrosion, and is suitable for corrosive environments such as marine and chemical industries.

[0023] 3. Simple molding process: The medium-entropy alloy of the present invention can obtain excellent mechanical properties and corrosion resistance through a simple casting process, and does not require complex heat treatment process for further processing, which simplifies the operation steps, reduces costs, and reduces waste or high-energy consumption links, thereby reducing environmental impact.

[0024] 4. Cost reduction: By adjusting the composition of the alloy, while ensuring performance, a large amount of relatively low-priced Fe element is used, so that the Fe atomic content reaches up to 70at%, which greatly reduces the raw material cost of the alloy and is conducive to the promotion and application of the alloy in the industrial field. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] Figure 1 XRD comparison patterns of low-cost, high-strength, tough, and corrosion-resistant cast medium-entropy alloys in Examples 1-4 of the present invention;

[0026] Figure 2This is a SEM comparison of the low-cost, high-strength, tough, and corrosion-resistant cast medium-entropy alloys in Examples 1-4 of the present invention;

[0027] Figure 3 This is a comparison chart of stress-strain curves of low-cost, high-strength, tough, and corrosion-resistant cast medium-entropy alloys in Examples 1-4 of the present invention;

[0028] Figure 4 This is a comparison chart of Tafel curves of low-cost, high-strength, tough, and corrosion-resistant cast medium-entropy alloys in Examples 1-4 of the present invention;

[0029] Figure 5 1 is a comparison chart of the yield strength, self-corrosion potential and cost of the low-cost, high-strength, tough, and corrosion-resistant cast medium-entropy alloy in Example 4 of the present invention and typical high-entropy alloys in the prior art. DETAILED DESCRIPTION

[0030] The present invention will be further described below with reference to specific embodiments. The illustrative embodiments and descriptions of the present invention are intended to explain the present invention but are not intended to limit the present invention.

[0031] All raw materials of the present invention are not particularly limited in their sources and can be purchased from the market or prepared according to conventional methods well known to those skilled in the art.

[0032] The devices used in the present invention are not particularly limited and can be devices commonly used in the art.

[0033] Example 1:

[0034] This embodiment proposes a low-cost, high-strength, tough, and corrosion-resistant cast medium-entropy alloy, the chemical formula of which is Fe3CrNiAl 0.37 Ti 0.37 , the microstructure is composed of FCC and BCC dual phases.

[0035] The preparation process of the above-mentioned low-cost, high-strength, tough, and corrosion-resistant casting medium-entropy alloy is as follows:

[0036] Using Fe, Cr, Ni, Al and Ti raw materials with purity greater than 99.9wt%, according to the chemical formula Fe3CrNiAl 0.37 Ti 0.37 The alloy was prepared by adjusting the molar ratio of the elements in the alloy. The alloy was melted in an arc melting furnace under a high-purity argon atmosphere (>99.99%) to produce an approximately 50g alloy ingot. To ensure uniform composition, the ingot was flipped and remelted at least four times. The ingot was then cut into dogbone tensile specimens with a gauge length of 10mm for tensile testing and rectangular specimens measuring 3×6×9mm for microstructural observation and corrosion testing.

[0037] Example 2:

[0038] The only difference between this embodiment and embodiment 1 is that the chemical formula of the low-cost, high-strength, and corrosion-resistant casting medium entropy alloy in this embodiment is Fe4CrNiAl 0.37 Ti 0.37 .

[0039] Example 3:

[0040] The only difference between this embodiment and embodiment 1 is that the chemical formula of the low-cost, high-strength, and corrosion-resistant casting medium entropy alloy in this embodiment is Fe5CrNiAl 0.37 Ti 0.37 .

[0041] Example 4:

[0042] The only difference between this embodiment and embodiment 1 is that the chemical formula of the low-cost, high-strength, and corrosion-resistant casting medium-entropy alloy in this embodiment is Fe6CrNiAl 0.37 Ti 0.37 .

[0043] Specifically, the samples in Examples 1-4 were analyzed and tested as follows:

[0044] 1. XRD analysis: The alloy was subjected to phase analysis using an Empyrean X-ray diffractometer with a Cu target and phase identification was performed using MDI Jade 6.0 software. It was determined that the alloy consisted of a dual phase of FCC and BCC.

[0045] 2. Mechanical properties test: Tensile tests were performed on dog-bone specimens using a UTM5105 universal testing machine at a speed of 0.5 mm / min. The test was repeated at least four times to ensure the reliability of the results.

[0046] 3. Corrosion resistance test: A CHI600 electrochemical workstation was used to perform potentiodynamic polarization tests in a 3.5 wt% NaCl aqueous solution with a saturated calomel electrode (SCE) as the reference electrode, Pt as the counter electrode, and a polished rectangular specimen as the working electrode. The scanning potential range was from -0.8 V to 1.4 V, and the scanning rate was 1 mV / s. The test was repeated at least three times to ensure the reliability of the results.

[0047] The results of mechanical property tests show that in the products of Examples 1-4, the yield strength reaches 982MPa, 923MPa, 732MPa, and 656MPa or more, respectively; the tensile strength reaches 1231MPa, 1218MPa, 1088MPa, and 1134MPa or more, respectively; and the plasticity reaches 5.2%, 8.0%, 14.7%, and 18.8% or more, respectively, all of which can meet the use requirements under complex stress conditions.

[0048] The corrosion resistance test results show that in the products of Examples 1-4, Fe3CrNiAl 0.37 Ti 0.37 The pitting potential of Fe4CrNiAl is 0.17V, the self-corrosion potential is -0.252V, 0.37 Ti 0.37 The pitting potential of Fe5CrNiAl is 0.816V, the self-corrosion potential is -0.129V, 0.37 Ti 0.37 The pitting potential of Fe6CrNiAl is 0.622V, the self-corrosion potential is -0.241V, 0.37 Ti 0.37 The pitting potential is 0.648V and the self-corrosion potential is -0.240V. It can be seen that the above products have excellent corrosion resistance.

[0049] Figures 1 to 5 The comparative results of the correlation analysis of the relevant products in Examples 1-4 are given in FIG. 4 , wherein:

[0050] Figure 1 XRD comparison patterns of low-cost, high-strength, tough, and corrosion-resistant cast medium-entropy alloys in Examples 1-4 of the present invention; Figure 2 This is a SEM comparison of the low-cost, high-strength, tough, and corrosion-resistant cast medium-entropy alloys in Examples 1-4 of the present invention; Figure 3 This is a comparison chart of stress-strain curves of low-cost, high-strength, tough, and corrosion-resistant cast medium-entropy alloys in Examples 1-4 of the present invention. Figure 4 This is a comparison chart of the Tafel curves of the low-cost, high-strength, tough, and corrosion-resistant cast medium-entropy alloys in Examples 1-4 of the present invention. Figure 5 1 is a comparison chart of the yield strength, self-corrosion potential and cost of the low-cost, high-strength, tough, and corrosion-resistant cast medium-entropy alloy in Example 4 of the present invention and typical high-entropy alloys in the prior art.

[0051] Figures 1-2 Fe3 in the formula refers to Fe3CrNiAl 0.37 Ti 0.37 , Fe4 refers to Fe4CrNiAl 0.37 Ti 0.37 , Fe5 refers to Fe5CrNiAl 0.37 Ti 0.37 , Fe6 refers to Fe6CrNiAl 0.37 Ti 0.37 , Figure 5 This Work refers to Fe6CrNiAl 0.37 Ti 0.37 .

[0052] Through the above comparison, it can be seen that compared with traditional steel materials, the medium entropy alloy of the present invention has higher strength and better plasticity, and can meet the use requirements under complex stress conditions. It also has outstanding corrosion resistance, which can show corrosion resistance comparable to that of stainless steel, has a higher self-corrosion potential and a higher pitting potential, can effectively resist local corrosion forms such as pitting corrosion, and is suitable for corrosive environments such as marine and chemical industries. In addition, the present application only requires a simple casting process to obtain excellent mechanical properties and corrosion resistance, and does not require a complex heat treatment process for re-processing, which simplifies the operation steps, reduces costs, and reduces waste or high-energy consumption links, reducing environmental impact. By adjusting the composition of the alloy, while ensuring performance, a large amount of relatively low-priced Fe elements are used, so that the atomic content of Fe reaches up to 70at%, which greatly reduces the raw material cost of the alloy, which is conducive to promotion and application in the industrial field.

[0053] 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 low-cost, high-strength, tough, and corrosion-resistant cast medium-entropy alloy, characterized in that: The chemical formula of the low-cost, high-strength, and corrosion-resistant casting medium entropy alloy is Fe x CrNiAl 0.37 Ti 0.37 , where the value of x ranges from 3 to 6.

2. A low-cost, high-strength, high-toughness, corrosion-resistant cast medium-entropy alloy according to claim 1, characterized in that: The microstructure of the low-cost, high-strength, tough, and corrosion-resistant cast medium-entropy alloy consists of a dual phase of FCC and BCC.

3. A low-cost, high-strength, high-toughness, corrosion-resistant cast medium-entropy alloy according to claim 1 or 2, characterized in that: The low-cost, high-strength, tough, and corrosion-resistant cast medium-entropy alloy is prepared by the following steps: S1, ingredients: according to the molar ratio of each element in the chemical formula of the low-cost, high-strength, tough, and corrosion-resistant cast medium-entropy alloy, respectively weigh the metal raw materials of Fe, Cr, Ni, Al, and Ti, and mix them to obtain a well-proportioned raw material; S2, smelting: the raw materials with good proportions are smelted in an arc melting furnace under a high-purity argon protection environment; S3, remelting: After the raw materials with the right proportions are completely melted and the composition is uniform, multiple remelting operations are performed to obtain an alloy melt; S4, cooling and solidification: injecting the alloy melt into the preheated mold for cooling and solidification to obtain an alloy ingot.

4. A low-cost, high-strength, high-toughness, corrosion-resistant cast medium-entropy alloy according to claim 3, characterized in that: In step S1, the purity of the metal raw materials of Fe, Cr, Ni, Al and Ti is greater than 99.9%.

5. The low-cost, high-strength, high-toughness, corrosion-resistant cast medium-entropy alloy according to claim 3, characterized in that: In step S2, the purity of the argon in the high-purity argon protection environment is greater than 99.99%.

6. A low-cost, high-strength, high-toughness, corrosion-resistant cast medium-entropy alloy according to claim 3, characterized in that: In step S3, the remelting is performed at least 4 times.

7. A low-cost, high-strength, high-toughness, corrosion-resistant cast medium-entropy alloy according to claim 1 or 2, characterized in that: The low-cost, high-strength, tough, and corrosion-resistant cast medium-entropy alloy has a yield strength of more than 656 MPa, a tensile strength of more than 1088 MPa, and a plasticity of more than 5.2%.

8. A low-cost, high-strength, high-toughness, corrosion-resistant cast medium-entropy alloy according to claim 1 or 2, characterized in that: The low-cost, high-strength, tough, and corrosion-resistant cast medium-entropy alloy was subjected to a potentiodynamic polarization test in a 3.5wt% NaCl aqueous solution using a saturated calomel electrode as a reference electrode and Pt as a counter electrode. The scanning potential range was from -0.8V to 1.4V, and the scanning rate was 1mV / s. The pitting potential was not less than 0.15V, and the self-corrosion potential was not less than -0.26V.

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