FeCrNiTiAl system high-entropy alloy based on amplitude modulation decomposition and preparation method of FeCrNiTiAl system high-entropy alloy

Abstract

The invention provides a FeCrNiTiAl system high-entropy alloy based on amplitude modulation decomposition, the component of the high-entropy alloy is FeCrNiTixAl (1-x), and x is equal to 0.1 to 0.2. The alloy is composed of a BCCA2 phase and a BCCB2 phase, according to X-ray diffraction, the lattice constants of the two phases are calculated to be # imgabs0 # and # imgabs1 # respectively, diffraction spots under a transmission electron microscope are micro-area spots, and the lattice constants of the two phases are calculated to be # imgabs2 # and # imgabs3 # respectively. Five main elements are adopted in component design, the alloy with excellent performance is prepared, and the requirement of industrial development is better met.

Description

Technical Field

[0001] The present invention belongs to the technical field of alloy casting, and relates to a FeCrNiTiAl-based high-entropy alloy based on spinodal decomposition and a preparation method thereof. Background Art

[0002] Due to problems such as brittleness of materials and difficult processing caused by the formation of intermetallic compounds and complex intermediate phases, traditional alloys are often designed with one or two main elements as the base, and other alloying elements are added on this basis to regulate the structure and properties of the materials. This alloy design method limits the available alloy systems. High-entropy alloys are alloys composed of multiple main elements. Since the solid solution composed of multiple main elements has a high mixing entropy and a more stable structure, FCC or BCC solid solutions with simple structures are often formed, effectively avoiding the formation of brittle precipitates when excessive alloying elements are added to traditional alloys. This makes high-entropy alloys have many excellent properties such as high strength, high temperature strength, oxidation resistance, and corrosion resistance, providing ideas for the design and development of new alloy systems with excellent comprehensive properties. Currently, there are mainly high-entropy alloy systems such as FeCoNiCrMn and FeCoNiCr, and most of them contain expensive strategic element Co. Moreover, when the existing alloy systems obtain high strength and hardness, the sacrifice of plasticity and toughness is serious, and the strength-plasticity matching of the alloys is poor, which greatly limits their engineering applications. Therefore, it is necessary to design alloy systems and compositions with excellent comprehensive properties. On the other hand, the preparation of existing bulk high-entropy alloys mainly uses vacuum arc melting method. Most high-entropy alloys will form coarse as-cast dendritic structures after melting and often need subsequent heat treatment to be used, which greatly increases energy consumption and production cycle. These problems limit the development and engineering applications of high-entropy alloys.

[0003] In summary, the problems existing in the development of current high-entropy alloys are the limitations in alloy composition design. How to achieve the coordinated improvement of strength and plasticity of high-entropy alloys through composition design and process innovation while controlling costs, and break through the bottleneck of preparation efficiency. Summary of the Invention

[0004] Aiming at the problems existing in the prior art, the present invention provides a FeCrNiTiAl-based high-entropy alloy based on spinodal decomposition and a preparation method thereof. By using 5 main elements, a high-entropy alloy with excellent properties is prepared, which has high preparation efficiency, simple process, and better meets the needs of industrial development.

[0005] The present invention is realized through the following technical solutions:

[0006] A FeCrNiTiAl-based high-entropy alloy based on spinodal decomposition, the composition of the FeCrNiTiAl-based high-entropy alloy is FeCrNiTi x Al 1-x, where x = 0.1 to 0.2.

[0007] Preferably, the FeCrNiTiAl high-entropy alloy is composed of BCC_A2 phase and BCC_B2 phase.

[0008] Preferably, the density of the FeCrNiTiAl high-entropy alloy is less than 6.6 g / cm 3 .

[0009] A preparation method of FeCrNiTiAl high-entropy alloy based on spinodal decomposition includes:

[0010] Mixing iron, chromium, nickel, titanium and aluminum elements according to the required components, and under the condition of vacuum pumping and protection of argon atmosphere, through arc melting, after cooling, a FeCrNiTiAl high-entropy alloy with spinodal decomposition is obtained.

[0011] Preferably, the vacuum intensity during vacuum pumping is 6.6×10 -3 Pa, and the vacuum intensity under the protection of argon atmosphere is -0.06 Mpa.

[0012] Preferably, the specific process of arc melting is that the current gradually rises from 0 A to 300 A, the current is maintained between 250 A and 300 A during melting, after melting for 3 minutes, the ingot is flipped and melted again, and melted repeatedly for many times to obtain a FeCrNiTiAl high-entropy alloy with spinodal decomposition.

[0013] Compared with the prior art, the present invention has the following beneficial technical effects:

[0014] In the FeCrNiTiAl high-entropy alloy based on spinodal decomposition of the present invention, the high-entropy alloy composition is FeCrNiTi x Al 1-x , where x = 0.1 to 0.2. The alloy is composed of BCC_A2 phase and BCC_B2 phase. According to X-ray diffraction, the lattice constants of the two phases are respectively and And the diffraction spots under the transmission electron microscope are micro-area spots, and the lattice constants of the two phases are respectively and The alloy of the present invention is an FeCrNiTiAl-based high-entropy alloy, which is different from the previous design concept of using one or two elements as the main elements. Five main elements are adopted in the composition design to prepare an alloy with excellent properties, which better meets the needs of industrial development. Different from high-entropy alloy systems such as FeCoNiCrMn and FeCoNiCr, the FeCrNiTiAl-based high-entropy alloy of the present invention abandons the expensive strategic scarce element Co and instead uses relatively cheap Ti element and Al element. By controlling the percentage content of each element, a high-entropy alloy system with excellent comprehensive properties is designed. The alloy of the present invention has excellent comprehensive mechanical properties by utilizing the spinodal decomposition that occurs under the as-cast cooling conditions during melting and ingot casting. The alloy can be used under the as-cast cooling conditions during melting and ingot casting without subsequent solution aging heat treatment, shortening the alloy preparation production cycle, reducing energy consumption, and having the advantage of low cost.

[0015] Furthermore, the density of the FeCrNiTiAl-based high-entropy alloy of the present invention is less than 6.6 g / cm 3 , the room temperature yield strength is higher than 1500 Mpa, the compressive fracture strength is about 2500 Mpa, the compressive strain is greater than 25%, and the hardness is greater than 500 HV 0.5 , and it is completely oxidation-resistant at 800 °C, 900 °C, and 1000 °C, having great application prospects in the engineering field. Description of the Drawings

[0016] Figure 1 is the optical micrograph of Example 1. Among them, Figure (a) is the metallographic structure under a low-power microscope, and Figure (b) is the metallographic structure under a high-power microscope;

[0017] Figure 2 is the XRD pattern of Examples 1 - 3;

[0018] Figure 3 is the room temperature compressive engineering stress-strain curve of Examples 1 - 3;

[0019] Figure 4 is the spinodal decomposition structure observed under a transmission electron microscope in Example 1;

[0020] Figure 5 is the polarization curve of Examples 1 - 3 in a 3.5 wt% NaCl solution;

[0021] Figure 6 is the high temperature compressive true stress-true strain curve of the cylindrical specimens of Examples 1 - 3. Detailed Embodiments

[0022] The present invention will be further described in detail below in conjunction with specific embodiments, which are explanations of the present invention rather than limitations.

[0023] In order to enable those skilled in the art to better understand the solution of the present invention, the technical solutions in the embodiments of the present invention will be clearly and completely described below 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. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without creative efforts shall fall within the scope of protection of the present invention.

[0024] A FeCrNiTiAl-based high-entropy alloy based on spinodal decomposition, and the composition of the high-entropy alloy is FeCrNiTi x Al 1-x , where x = 0.1 - 0.2.

[0025] Furthermore, the density of the high-entropy alloy is less than 6.6 g / cm 3 .

[0026] The preparation method of the above-mentioned FeCrNiTiAl-based high-entropy alloy based on spinodal decomposition is carried out in a high-vacuum multifunctional arc melting furnace, and includes the following steps:

[0027] The raw materials all adopt pure iron, chromium, nickel, titanium, and aluminum elements with a purity greater than or equal to 99.9%, and are proportioned according to the required components.

[0028] During the melting process, to prevent the alloy from being oxidized, first evacuate the vacuum. When the vacuum gauge indicates 6.6×10 -3 Pa, close the vacuum gauge, and then fill argon for atmosphere protection so that the vacuum pressure gauge indicates -0.06 MPa; then carry out arc melting. The current is slowly increased from 0 A to 300 A. During melting, ensure that the current is between 250 A and 300 A. After melting for about 3 minutes, turn over the ingot and melt it again. Each component alloy sample is melted four times to ensure the uniformity of the final as-cast alloy composition.

[0029] Keep the alloy ingot obtained by the above melting under the same high-purity argon protection state during melting and cool it to room temperature in the melting furnace to obtain the required high-entropy alloy material.

[0030] Example 1

[0031] A preparation method of a FeCrNiTiAl-based high-entropy alloy based on spinodal decomposition, and the components are: FeCrNiTi 0.1 Al 0.9 , and the preparation method is to carry out melting in a non-consumable vacuum arc melting furnace. The specific method is as follows:

[0032] Using pure iron, chromium, nickel, titanium, and aluminum elements with a purity greater than 99 wt.%, proportion them according to the required components, and then melt them in a high-vacuum multi-functional arc melting furnace. When melting, first evacuate the vacuum. When the vacuum gauge indicates 6.6×10 -3 Pa, close the vacuum gauge, and then fill with argon for atmosphere protection until the vacuum pressure gauge indicates -0.06 MPa; then start arc melting, slowly increase the current from 0 A to 300 A, ensure the current is between 250 A and 300 A during melting. After melting for about 3 minutes, flip the ingot and melt again. Each component alloy sample is melted four times to ensure the uniformity of the final as-cast alloy composition.

[0033] Keep the alloy ingot obtained from the above melting under the same high-purity argon protection state during melting and cool it to room temperature in the melting furnace, then the desired high-entropy alloy material is obtained.

[0034] Example 2

[0035] A preparation method of an FeCrNiTiAl-based high-entropy alloy based on spinodal decomposition, with the components: FeCrNiTi 0.15 Al 0.85 , and the preparation method is to melt in a non-consumable vacuum arc melting furnace. The specific method is as follows:

[0036] Using pure iron, chromium, nickel, titanium, and aluminum elements with a purity greater than 99 wt.%, proportion them according to the required components, and then melt them in a high-vacuum multi-functional arc melting furnace. When melting, first evacuate the vacuum. When the vacuum gauge indicates 6.6×10 -3 Pa, close the vacuum gauge, and then fill with argon for atmosphere protection until the vacuum pressure gauge indicates -0.06 MPa; then start arc melting, slowly increase the current from 0 A to 300 A, ensure the current is between 250 A and 300 A during melting. After melting for about 3 minutes, flip the ingot and melt again. Each component alloy sample is melted four times to ensure the uniformity of the final as-cast alloy composition.

[0037] Keep the alloy ingot obtained from the above melting under the same high-purity argon protection state during melting and cool it to room temperature in the melting furnace, then the desired high-entropy alloy material is obtained.

[0038] Example 3

[0039] A preparation method of an FeCrNiTiAl-based high-entropy alloy based on spinodal decomposition, with the components: FeCrNiTi 0.2 Al 0.8 , and the preparation method is to melt in a non-consumable vacuum arc melting furnace. The specific method is as follows:

[0040] Pure iron, chromium, nickel, titanium, and aluminum elements with a purity greater than 99 wt.% are used and proportioned according to the required components, and then melted in a high-vacuum multi-functional arc melting furnace. During melting, first evacuate the vacuum. When the vacuum gauge indicates 6.6×10 -3 Pa, close the vacuum gauge, and then fill argon for atmosphere protection until the vacuum pressure gauge indicates -0.06 MPa; then strike an arc for melting, slowly raise the current from 0 A to 300 A, ensure that the current is between 250 A and 300 A during melting, turn over the ingot and melt again after about 3 min of melting, and melt each component alloy sample four times to ensure the uniformity of the final as-cast alloy composition.

[0041] Under the same high-purity argon protection state during melting, cool the alloy ingot obtained by the above melting in the melting furnace to room temperature, and the desired high-entropy alloy material is obtained.

[0042] Figure 1 is the optical micrograph of Example 1 FeCrNiTi 0.1 Al 0.9 , where Fig. a) is the metallographic structure under a low-power microscope, and Fig. b) is the metallographic structure under a high-power microscope. Figure 2 is Example 1 FeCrNiTi 0.1 Al 0.9 , Example 2 FeCrNiTi 0.15 Al 0.85 , Example 3 FeCrNiTi 0.2 Al 0.8 XRD patterns. Figure 3 is Example 1 FeCrNiTi 0.1 Al 0.9 , Example 2 FeCrNiTi 0.15 Al 0.85 , Example 3 FeCrNiTi 0.2 Al 0.8 room-temperature compression engineering stress-strain curves. Figure 4 is the spinodal decomposition structure observed under a transmission electron microscope in Example 1. It can be seen from the figure that the phase composition of the FeCrNiTi 0.1 Al 0.9 alloy is the BCC_A2 phase and the BCC_B2 phase. The grain size is uniform and fine, and excellent comprehensive mechanical properties are generated due to spinodal decomposition.

[0043] FeCrNiTi 0.1 Al 0.9 , FeCrNiTi 0.15 Al 0.85 , FeCrNiTi 0.2 Al 0.8(Corresponding to Examples 1, 2, and 3 respectively), the main room temperature mechanical property indexes are shown in Table 1;

[0044] Table 1 shows the 0.1 Al 0.9 , 0.15 Al 0.85 , 0.2 Al 0.8 room temperature mechanical properties

[0045]

[0046] index data

[0047] Figure 5 for 0.1 Al 0.9 , 0.15 Al 0.85 , 0.2 Al 0.8 (Corresponding to Examples 1, 2, and 3 respectively) polarization curves in 3.5 wt% NaCl solution.

[0048] The 0.1 Al 0.9 , 0.15 Al 0.85 , 0.2 Al 0.8 room temperature corrosion resistance indexes are shown in Table 2,

[0049] Table 2 shows the 0.1 Al 0.9 , 0.15 Al 0.85 , 0.2 Al 0.8 room temperature corrosion resistance index data

[0050] alloy Example 1 Example 2 Example 3 E (Volts) -0.403 -0.302 -0.498 <![CDATA[I (Amp / cm 2 )]]> <![CDATA[6.196*10 -7 > <![CDATA[4.572*10 -7 > <![CDATA[4.64*10 -7 >

[0051] Figure 6 for 0.1 Al 0.9 , 0.15 Al 0.85 , 0.2 Al 0.8 (Examples 1, 2, and 3 respectively) true stress-true strain curves of cylindrical specimens compressed at 800 °C.

[0052] The0.1 Al 0.9 、FeCrNiTi 0.15 Al 0.85 、FeCrNiTi 0.2 Al 0.8 (Performance indicators at 800 °C for Examples 1, 2, and 3 respectively) are shown in Table 3;

[0053] Table 3 shows the performance indicator data of Examples 1 to 3 at 800 °C

[0054]

[0055]

[0056] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the technical field to which this invention belongs. The terms used in the description of this invention herein are for the purpose of describing specific embodiments only and are not intended to limit the invention. The term "and / or" used herein includes any and all combinations of one or more of the related listed items.

[0057] As described above, it is only a preferred embodiment of this invention and does not impose any form of limitation on this invention; any ordinary technician in this industry can smoothly implement this invention as shown in the accompanying drawings of the specification and as described above; however, any minor changes, modifications, and equivalent variations made by those skilled in this professional field without departing from the technical solution of this invention and using the technical content disclosed above are equivalent embodiments of this invention; at the same time, any equivalent changes, modifications, and variations made to the above embodiments based on the essence of this invention still fall within the protection scope of the technical solution of this invention.

Claims

1. A FeCrNiTiAl-based high-entropy alloy based on modulated decomposition, characterized in that, The composition of the FeCrNiTiAl high-entropy alloy is FeCrNiTi x Al 1-x , where x = 0.1 - 0.

2.

2. A FeCrNiTiAl-based high-entropy alloy based on spinodal decomposition according to claim 1, characterized in that, The FeCrNiTiAl high-entropy alloy is composed of a BCC_A2 phase and a BCC_B2 phase.

3. A FeCrNiTiAl-based high-entropy alloy based on spinodal decomposition according to claim 1, characterized in that, The density of the FeCrNiTiAl-based high-entropy alloy is less than 6.6 g / cm 3 .

4. A preparation method of a FeCrNiTiAl-based high-entropy alloy based on spinodal decomposition according to any one of claims 1-3, characterized in that, Including, Iron, chromium, nickel, titanium, and aluminum elements are proportioned according to the required components. Under the condition of vacuum pumping and protected by an argon atmosphere, through arc melting, after cooling, a spinodal decomposition FeCrNiTiAl high-entropy alloy is obtained.

5. The preparation method of a FeCrNiTiAl-based high-entropy alloy based on spinodal decomposition according to claim 4, characterized in that, The vacuum intensity during vacuum pumping is 6.6×10 -3 Pa, and the vacuum intensity under argon atmosphere protection is -0.06 Mpa.

6. The preparation method of a FeCrNiTiAl-based high-entropy alloy based on spinodal decomposition according to claim 4, characterized in that, The specific process of the arc melting is that the current gradually rises from 0 A to 300 A. During melting, the current is maintained between 250 A and 300 A. After melting for 3 minutes, the ingot is flipped and melted again. After repeated melting for many times, a spinodal decomposition FeCrNiTiAl high-entropy alloy is obtained.

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