A low-density carbide-reinforced FCC / B2 dual-phase high-entropy alloy and its preparation method

Abstract

This invention provides a low-density carbide-reinforced FCC / B2 dual-phase high-entropy alloy and its preparation method, belonging to the field of novel metallic materials technology. The low-density carbide-reinforced FCC / B2 dual-phase high-entropy alloy is composed of the following molar percentage components: Al: 14-17 at.%, Cr: 9-12 at.%, Fe: 32-36 at.%, Ni: 34-38 at.%, Ti: 0-0.6 at.%, V: 0-0.1 at.%, Mn: 0-0.02 at.%, Zr: 0-0.04 at.%, B: 0-0.05 at.%, C: 2-4 at.%; 0 ≤ Ti / C ≤ 0.3. The low-density carbide-reinforced FCC / B2 high-entropy alloy of this invention possesses both good room-temperature tensile strength and plasticity, and its density can reach as low as 7.15 g / cm³. 3 This technology overcomes the shortcomings of existing technologies, meets the demand for lightweight and high-performance metal structural materials, and provides a new alloying composition option for FCC / B2 dual-phase high-entropy alloys.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of new metal materials, and relates to a low-density carbide-reinforced FCC / B2 dual-phase high-entropy alloy and a preparation method thereof. BACKGROUND

[0002] Metal materials are required to have low density, low cost, oxidation resistance, high strength and other properties in the fields of aerospace, etc. In traditional alloys, the design method of one or two elements as main elements seriously limits the number of available alloy systems, making the development of traditional alloy systems saturated, and it is difficult to meet the increasing actual needs of the aerospace field for the performance of metal materials. In recent years, the design concept of high-entropy alloy / multi-main element alloy has opened up a huge, undeveloped alloy composition field, providing a large number of new alloy systems for development. Among them, the design of dual-phase high-entropy alloys with soft and hard phases is one of the effective strategies to realize good matching of room temperature / high temperature strength and plasticity. The newly developed FCC(face-centered cubic) / B2(order-centered cubic) dual-phase high-entropy alloy has excellent room temperature mechanical properties, good casting performance, simple preparation process and other advantages, and is very friendly to engineering application, and is an alloy type with application potential.

[0003] However, the strengthening phase type of the existing FCC / B2 dual-phase high-entropy alloy is relatively single. Existing studies have shown that, for example, AlCoCrFeNi 2.1 high-entropy alloy, Fe 37 Ni 36 Cr 10 Al 17 high-entropy alloy, the room temperature tensile strength under the as-cast state is not more than 1200 MPa. The mechanical properties of the FCC / B2 dual-phase high-entropy alloy are still difficult to meet the requirements of high-strength and high-toughness structural materials. Even though the introduction of dislocations or induced recrystallization through deformation heat treatment can effectively strengthen and toughen the alloy, such a method is only suitable for simple shape components such as pipes, plates and rods, and it is difficult to realize the strengthening and toughening of complex components. Therefore, obtaining a directly cast high-entropy alloy with excellent room temperature mechanical properties is still a challenge.

[0004] In order to solve the problem of insufficient room temperature tensile strength of the as-cast FCC / B2 dual-phase high-entropy alloy, many studies promote the formation of high-density precipitated strengthening phases through alloying elements to improve the room temperature strength of the FCC / B2 cast high-entropy alloy. As for the current alloying method, most of the alloying elements are limited to transition metal elements such as Nb, Mo and W, which have high cost and greatly increase the density of the alloy, thereby limiting the application of the FCC / B2 dual-phase high-entropy alloy. Therefore, the current alloying method still has certain limitations, and it is urgent to develop a new type of light high-strength FCC / B2 dual-phase high-entropy alloy. SUMMARY

[0005] The purpose of this invention is to overcome the shortcomings of the prior art and provide a low-density carbide-reinforced FCC / B2 dual-phase high-entropy alloy and its preparation method, so as to address the problem of insufficient strength of as-cast FCC / B2 high-entropy alloys in the prior art and solve the problem that current alloying methods are difficult to achieve lightweighting.

[0006] To achieve the above objectives, the present invention employs the following technical solution:

[0007] A low-density carbide-reinforced FCC / B2 dual-phase high-entropy alloy, comprising, by molar percentage:

[0008] Al: 14-17at.%, Cr: 9-12at.%, Fe: 32-36at.%, Ni: 34-38at.%, Ti: 0-0.6at.%, V: 0-0 .1at.%, Mn: 0-0.02at.%, Zr: 0-0.04at.%, B: 0-0.05at.%, C: 2-4at.%; 0≤Ti / C≤0.3;

[0009] The FCC / B2 dual-phase high-entropy alloy contains a carbide-reinforced phase.

[0010] A further improvement of the present invention is that:

[0011] Preferably, in mole percentage, it includes:

[0012] Al: 15-17at.%, Cr: 10-12at.%, Fe: 32-35at.%, Ni: 34-36at.%, Ti: 0.2-0.5at.%, V: 0-0.1at .%, Mn: 0-0.01at.%, Zr: 0.01-0.03at.%, B: 0.01-0.05at.%, C: 2.5-4at.%; 0.05≤Ti / C≤0.2.

[0013] Preferably, the dual-phase high-entropy alloy has a room temperature tensile strength ≥1300 MPa, an elongation at break ≥10%, and an alloy density ≤7.2 g / cm³. 3

[0014] Preferably, the FCC / B2 dual-phase high-entropy alloy comprises an FCC phase and a B2 phase, and the carbide-reinforcing phase comprises Cr7C3 and TiC carbides.

[0015] A method for preparing the above-mentioned low-density carbide-reinforced FCC / B2 dual-phase high-entropy alloy includes the following steps:

[0016] According to the target composition, Ni, Fe, Cr, Al, Ti, and Fe-C alloy were weighed, ultrasonically cleaned with anhydrous ethanol, and then placed in a melting furnace for melting under argon atmosphere. After casting and cooling, the as-cast FCC / B2 dual-phase high-entropy alloy was obtained.

[0017] Preferably, the carbon content in the Fe-C alloy is 5 to 10 wt.%.

[0018] Preferably, during the smelting process, Ti ingots are first smelted with a current of 140–160 A; then the raw materials are smelted multiple times with a current of 200–220 A.

[0019] Preferably, the raw material is melted by a current of 200-220A ≥ 5 times, with each melting lasting 5 minutes.

[0020] Preferably, electromagnetic stirring is added during the smelting process.

[0021] Preferably, the casting process is based on copper mold casting, and the arc gun current is 220-240A during casting.

[0022] Compared with the prior art, the present invention has the following beneficial effects:

[0023] This invention provides a low-density carbide-reinforced FCC / B2 dual-phase high-entropy alloy and its preparation method, relating to the field of novel metallic materials technology. The low-density carbide-reinforced FCC / B2 dual-phase high-entropy alloy is composed of the following molar percentage components: Al: 14-17 at.%, Cr: 9-12 at.%, Fe: 32-36 at.%, Ni: 34-38 at.%, Ti: 0-0.6 at.%, V: 0-0.1 at.%, Mn: 0-0.02 at.%, Zr: 0-0.04 at.%, B: 0-0.05 at.%, C: 2-4 at.%; 0 ≤ Ti / C ≤ 0.3. This invention's low-density carbide-reinforced high-entropy alloy exhibits both good room-temperature tensile strength and ductility, with a minimum density of only ~7.15 g / cm³. 3 This alloy meets the demand for lightweight, high-performance metallic structural materials. It also offers the following advantages:

[0024] 1. The low-density carbide-reinforced FCC / B2 dual-phase high-entropy alloy provided by this invention contains a relatively high amount of light Al, which promotes the formation of the B2 phase. This alloy also does not contain high-density, high-cost elements such as Co, Mo, and W, possessing advantages such as low density, low cost, and oxidation resistance. Even though elements such as Mo and W have the effect of promoting grain refinement and solid solution strengthening, this invention achieves a similar or even superior strengthening effect by adding the non-metallic element C. First, C pins grain boundaries by forming dispersed carbide particles, effectively promoting grain refinement. Furthermore, C, as an interstitial atom, forms solid solutions with other elements, often leading to higher lattice distortion, thereby strengthening the alloy. Finally, the addition of C helps improve melt fluidity, increases volume expansion during solidification, and to some extent avoids casting defects, which is beneficial to the stability of the microstructure and mechanical properties of the cast alloy.

[0025] 2. The Cr7C3 carbide formed by the combination of carbon (C) and chromium (Cr) can enhance the strength and hardness of the alloy. However, if too much C is added, coarse primary Cr7C3 carbide phases will form, causing severe embrittlement of the alloy and reducing its strength and ductility. Therefore, the amount of C added in most NiFe-based alloys is usually relatively small. This invention, through compositional control, ensures that when the amount of C added is relatively large, the FCC phase and carbides undergo a eutectic reaction in the liquid phase. This reaction is faster and significantly limits the coarsening of the Cr7C3 carbide. Therefore, the alloy of this invention can form relatively fine eutectic carbides with a size between 100-400 nm, achieving a significant strengthening effect with minimal sacrifice in ductility. This demonstrates the broad compositional and performance control space of the carbide-reinforced FCC / B2 high-entropy alloy of this invention.

[0026] 3. This invention emphasizes the Ti / C ratio because an appropriate amount of Ti and C can form fine TiC particles, which not only effectively strengthen the alloy but also act as heterogeneous nucleation sites for Cr7C3 carbides during solidification, effectively refining the Cr7C3 carbides. This significantly improves the room temperature strength of the alloy while maintaining good plasticity. By controlling a suitable Ti / C ratio (0≤Ti / C≤0.3), finer Cr7C3 and TiC strengthening phases can precipitate in the alloy, and the TiC is coherent with the matrix, thus endowing the alloy with excellent strength and plasticity.

[0027] 4. Most of the cast alloys in this invention have a room temperature tensile strength exceeding 1300 MPa, a fracture elongation exceeding 10%, and a density ≤ 7.2 g / cm³. 3 This new alloy has potential applications in aerospace, nuclear industry and other fields, and is expected to reduce the weight of related components by more than 10%. Attached Figure Description

[0028] Figure 1Secondary electron image of the high-entropy alloy provided in Example 1;

[0029] Figure 2 Uniaxial tensile curves of the high-entropy alloy provided in Example 1 at room temperature;

[0030] Figure 3 Secondary electron images of the high-entropy alloys provided in Example 2 and Comparative Example 2;

[0031] Figure 4 Uniaxial tensile curves of the high-entropy alloys provided in Example 2 and Comparative Example 2 at room temperature;

[0032] Figure 5 Backscattered electron images of the high-entropy alloys provided in Example 3 and Comparative Example 3;

[0033] Figure 6 The uniaxial tensile curves of the high-entropy alloys provided in Example 3 and Comparative Example 3 at room temperature. Detailed Implementation

[0034] To enable those skilled in the art to understand the features and effects of the present invention, the terms and expressions used in the specification and claims are explained and defined in general below. Unless otherwise specified, all technical and scientific terms used herein have the ordinary meaning understood by those skilled in the art regarding the present invention, and in case of conflict, the definitions in this specification shall prevail.

[0035] In this article, unless otherwise specified, “contains,” “includes,” “containing,” “has,” or similar terms cover the meanings of “composed of” and “mainly composed of,” for example, “A contains a” covers the meanings of “A contains a and others” and “A contains only a.”

[0036] The present invention will be further illustrated below with reference to specific embodiments. It should be understood that these embodiments are for illustrative purposes only and are not intended to limit the scope of the invention. Furthermore, it should be understood that after reading the teachings of this invention, those skilled in the art can make various alterations or modifications to the invention, and these equivalent forms also fall within the scope defined by the appended claims.

[0037] The following examples use instruments and equipment conventional in the art. Experimental methods in the following examples, unless otherwise specified, are generally performed under conventional conditions or as recommended by the manufacturer. All raw materials used in the following examples are conventional commercially available products with specifications conventional in the art. In this specification and the following examples, unless otherwise specified, "%" refers to weight percentage, "parts" refers to parts by weight, and "ratio" refers to weight proportion.

[0038] The first aspect of this invention discloses a low-density carbide-reinforced FCC / B2 dual-phase high-entropy alloy, composed of the following components in molar percentage:

[0039] Al: 14-17at.%, Cr: 9-12at.%, Fe: 32-36at.%, Ni: 34-38at.%, Ti: 0-0.6at.%, V: 0-0 .1at.%, Mn: 0-0.02at.%, Zr: 0-0.04at.%, B: 0-0.05at.%, C: 2-4at.%; 0≤Ti / C≤0.3.

[0040] In some embodiments of the present invention, the low-density carbide-reinforced FCC / B2 dual-phase high-entropy alloy is composed of the following components in molar percentage:

[0041] Al: 15-17at.%, Cr: 10-12at.%, Fe: 32-35at.%, Ni: 34-36at.%, Ti: 0.2-0.5at.%, V: 0-0.1at .%, Mn: 0-0.01at.%, Zr: 0.01-0.03at.%, B: 0.01-0.05at.%, C: 2.5-4at.%; 0.05≤Ti / C≤0.2.

[0042] In this process, the modification and refinement of carbide size can be achieved by controlling the Ti / C ratio. A lower Ti / C ratio yields finer TiC particles. Furthermore, increasing the Al and Cr content promotes the formation of the B2 phase, thereby increasing its volume fraction and contributing to improved room-temperature strength.

[0043] A second aspect of the present invention discloses a method for preparing a low-density carbide-reinforced FCC / B2 dual-phase high-entropy alloy, comprising the following steps:

[0044] The molar percentage of each element was converted to a mass percentage. Based on the total mass of a 40g alloy ingot, the mass of each element's corresponding raw material was accurately weighed using an analytical balance. The weighed raw materials, including Ni, Fe, Cr, Al, Ti, and Fe-C master alloys, were placed in a copper crucible in a melting furnace. The furnace was evacuated and repeatedly purged with argon gas. The raw materials were then melted under an argon protective atmosphere. The resulting carbide-reinforced high-entropy alloy circular ingot was placed on a copper mold for casting. After the alloy ingot cooled, the copper mold was removed, yielding an ingot with dimensions of 70×10×5mm. 3 Plate-shaped cast alloy sample.

[0045] In some embodiments of the present invention, the elemental metals such as Ni, Fe, Cr, Al, and Ti are all selected from industrial-grade pure raw materials with a purity of 99.95 wt.% or higher, while the carbon element is added through an Fe-C master alloy (carbon content 5-10 wt.%), which can improve the control precision of the carbon content. The raw materials are ultrasonically cleaned with anhydrous ethanol to remove impurities.

[0046] In some embodiments of the present invention, the weighing error of each raw material is within ±0.01g during the preparation process.

[0047] In some embodiments of the present invention, the smelting furnace is a non-consumable vacuum electric arc furnace.

[0048] In some embodiments of the present invention, after the raw materials are placed in a vacuum arc melting furnace, a mechanical pump is used to evacuate the vacuum to 3 × 10⁻⁶. 0 Below Pa, a molecular pump was then used to continue evacuating the vacuum to 3 × 10⁻⁶ Pa. -3 Below Pa. Then, high-purity argon gas is introduced to -0.05 MPa and vacuum is evacuated again to remove oxygen from the furnace cavity. This step is repeated twice.

[0049] In some embodiments of the present invention, high-purity argon gas is introduced again to -0.05MPa as a protective gas before smelting the raw material. Ti ingots are smelted for 10 minutes at a current of 140-160A to further remove excess oxygen. Then, the raw material is continuously smelted at least 5 times at a current of 200-220A, while an electromagnetic stirring current of 1A is turned on to promote melt flow. Each smelting time is 5 minutes.

[0050] In some embodiments of the present invention, the arc gun current is 220-240A during casting, causing the alloy ingot to melt and flow into the copper mold.

[0051] Example 1

[0052] A low-density carbide-reinforced FCC / B2 dual-phase high-entropy alloy is composed of the following components in molar percentage:

[0053] Al: 16.5at.%, Cr: 11.6at.%, Fe: 33.8at.%, Ni: 34.8at.%, C: 3.3at.%;

[0054] The above-mentioned carbide-reinforced FCC / B2 dual-phase high-entropy alloy was prepared according to the following steps:

[0055] 1. Batching: Convert the molar percentage of elements to mass percentage. Based on the total mass of a 40g alloy ingot, accurately weigh the raw materials of each element using an analytical balance, controlling the error within ±0.01g. Ni, Fe, Cr, Al, and Ti are all selected from industrial-grade pure raw materials with a purity of 99.95wt.% or higher, while C is added through an Fe-C master alloy (carbon content 5-10wt.%). Accordingly, the required mass of high-purity Fe needs to be subtracted from the mass of Fe in the master alloy.

[0056] 2. Melting: Place the weighed raw materials, such as Ni, Fe, Cr, Al, Ti, and Fe-C alloy, into the copper crucible of a non-consumable vacuum arc furnace. Evacuate the furnace chamber to 3×10⁻⁶. -3 The pressure is below -0.05 MPa, then high-purity argon is introduced to -0.05 MPa as a protective gas. This step is repeated twice to remove oxygen. Subsequently, Ti ingots are melted with a current set to 160 A to further remove excess oxygen. The raw material is then continuously melted 5 times with a current set to 220 A, while a 1 A electromagnetic stirring current is turned on to promote melt flow. Each melting cycle lasts 5 minutes to ensure that a uniform alloy round ingot is obtained.

[0057] 3. Casting: Place the obtained carbide-reinforced high-entropy alloy circular ingot above a copper mold, adjust the arc gun current to 230A to melt the alloy and pour it into the copper mold. After the alloy ingot cools, remove the copper mold to obtain a size of 70×10×5mm. 3 Plate-shaped cast high-entropy alloy sample.

[0058] Figure 1 The image shows the microstructure of the carbide-reinforced FCC / B2 dual-phase high-entropy alloy from Example 1, revealing a unique carbide-reinforced multiphase structure. Rod-shaped eutectic Cr7C3 carbides are dispersed within the FCC matrix, while a magnified image of the B2 phase shows high-density nanospherical BCC reinforcing phase particles. This indicates that the addition of carbon introduces high-density carbides to strengthen the FCC phase while retaining the original BCC reinforcing phase, resulting in excellent tensile strength in the alloy. Figure 2 The tensile engineering stress-strain curves of the carbide-reinforced FCC / B2 dual-phase high-entropy alloy in Example 1 are shown at room temperature. It can be seen that the alloy of this invention exhibits excellent yield strength (610 MPa), tensile strength (1264 MPa), and elongation (9.5%).

[0059] Example 2

[0060] A low-density carbide-reinforced FCC / B2 dual-phase high-entropy alloy is prepared using the same method as in Example 1, except that the raw materials are weighed according to the following molar percentages:

[0061] Al: 16.4at.%, Cr: 11.6at.%, Fe: 33.3at.%, Ni: 34.8at.%, Ti: 0.6at.%, C: 3.3at.%; Ti / C=0.18.

[0062] Comparative Example 2

[0063] Al: 16.4at.%, Cr: 11.6at.%, Fe: 32.4at.%, Ni: 34.8at.%, Ti: 1.5at.%, C: 3.3at.%; Ti / C=0.45.

[0064] The preparation method is the same as in Example 1.

[0065] The microstructures of Example 2 and Comparative Example 2 are as follows Figure 3 As shown, the alloy in Example 2 is mainly composed of two phases, FCC and B2, with two mixed carbides of different light and dark contrasts dispersed in the FCC matrix. To further determine the composition of the carbide-reinforcing phases in this alloy, EDS compositional analysis was performed, revealing a Ti-rich TiC phase and a Cr-rich Cr7C3 phase. Furthermore, some Cr7C3 carbides were found attached to the edges of the dark TiC particles, indicating that the pre-solidified TiC particles can serve as heterogeneous nucleation sites for Cr7C3 carbides, promoting carbide refinement and homogenization. In contrast, the alloy in Comparative Example 2 also uses FCC and B2 phases as its matrix, but the TiC particles are larger and continuously distributed at the phase boundaries. This distribution characteristic easily leads to stress concentration during deformation, causing phase boundary embrittlement, which is detrimental to mechanical properties. Figure 4 The tensile engineering stress-strain curves of the carbide-reinforced high-entropy alloys obtained in Example 2 and Comparative Example 2 are shown. The yield strength and tensile strength of the carbide-reinforced high-entropy alloy in Example 2 are 645 MPa and 1303 MPa, respectively, with a fracture elongation of 11.4%, achieving excellent tensile strength and plasticity matching. The yield strength and tensile strength of the alloy in Comparative Example 2 are 607 MPa and 1167 MPa, respectively, while the fracture elongation is reduced to 6.1%. This indicates that when the Ti / C ratio is too high, the large-sized blocky TiC precipitates near the phase boundary significantly impairs the mechanical properties of the alloy. This comparative example fully illustrates the importance of matching the C and Ti contents.

[0066] Example 3

[0067] A low-density carbide-reinforced FCC / B2 dual-phase high-entropy alloy was prepared by melting Ti ingots with a current of 140A; then, the raw materials were melted eight times with a current of 200A; during casting, the arc gun was used for casting at 220A. The remaining unrelated parts were the same as in Example 1. Furthermore, the raw materials were weighed according to the following molar percentage composition:

[0068] Al: 16.4at.%, Cr: 11.6at.%, Fe: 33.2at.%, Ni: 34.6at.%, Ti: 0.48at.%, V: 0.02at.%, C: 3.7at.%; Ti / C=0.13.

[0069] Comparative Example 3

[0070] Al: 16.4at.%, Cr: 11.5at.%, Fe: 31.8at.%, Ni: 34.6at.%, Ti: 1.93at.%, V: 0.07at.%, C: 3.7at.%; Ti / C=0.52.

[0071] The preparation method is the same as in Example 1.

[0072] Figure 5 The images show the microstructures of the carbide-reinforced FCC / B2 dual-phase high-entropy alloys obtained in Example 3 and Comparative Example 3. It can be seen that high-density carbides are distributed within the FCC phase and at the FCC / B2 phase boundary in the alloy of Example 3, forming serrated phase boundaries. The EDS surface mapping reflects the non-uniform distribution of Ti and Cr elements, with Cr being more densely distributed in the FCC phase, indicating that the main carbide type is Cr7C3, while TiC is less abundant and smaller in size. In contrast, due to the smaller amount of V added, its elemental distribution is more uniform overall and it is not enriched in the carbides. In Comparative Example 3, the TiC particle density is significantly increased, and relatively coarse TiC phases are formed in the FCC, B2 phases, and at the FCC / B2 phase boundary. Figure 5 The tensile stress-strain curves of the carbide-reinforced high-entropy alloys obtained in Example 3 and Comparative Example 3 are shown. The as-cast high-entropy alloy in Example 3 exhibits excellent comprehensive mechanical properties, with a yield strength of 656 MPa and a tensile strength of 1338 MPa, and an elongation at break of 10.8%. The alloy has a density of only 7.15 g / cm³. 3 This is lower than almost all as-cast FCC / B2 dual-phase alloys reported to date. The yield strength and tensile strength of the alloy in Comparative Example 3 were 580 MPa and 1050 MPa, respectively, with an elongation of only 4.4%, indicating that this composition is not suitable.

[0073] Example 4

[0074] A low-density carbide-reinforced FCC / B2 dual-phase high-entropy alloy was prepared by melting Ti ingots with a current of 150A; then, the raw materials were melted six times with a current of 210A; during casting, the arc gun was used for casting at 240A. The remaining unrelated parts were the same as in Example 1. Furthermore, the raw materials were weighed according to the following molar percentage composition:

[0075] Al: 17at.%, Cr: 12at.%, Fe: 34.6at.%, Ni: 34at.%, Ti: 0.4at.%, C: 2at.%; Ti / C=0.2.

[0076] Comparative Example 4

[0077] Al: 17at.%, Cr: 12at.%, Fe: 33.5at.%, Ni: 34at.%, Ti: 1.5at.%, C: 2at.%; Ti / C=0.75.

[0078] The preparation method is the same as in Example 1.

[0079] Room temperature tensile tests were conducted on Example 4 and Comparative Example 4. The alloy obtained in Example 4 showed a yield strength of 582 MPa, a tensile strength of 1250 MPa, and maintained good plasticity of 14%. The alloy obtained in Comparative Example 4 had a yield strength of 532 MPa and a tensile strength of 1160 MPa, with a plasticity of only 7%.

[0080] Example 4 and Comparative Example 4 further illustrate the importance of controlling the Ti / C ratio. Without Ti, the carbide in the alloy is a single Cr7C3. Compared to existing technologies, the Cr7C3 in the alloy of this invention solidifies as an FCC / carbide eutectic, thus exhibiting a smaller size and more dispersed distribution, maintaining good plasticity even with high C additions. The addition of Ti promotes the precipitation of TiC carbides. These carbides have a face-centered cubic structure and are semi-coherent with the matrix, effectively suppressing plasticity loss compared to incoherent interfaces. Furthermore, TiC, as a heterogeneous nucleation site, can further refine the Cr7C3 carbide during solidification, thereby enhancing the strong-plastic bonding of the alloy. To prevent excessive coarse TiC from adversely affecting the strong-plasticity of the FCC / B2 dual-phase high-entropy alloy, the Ti / C ratio needs to be controlled below 0.3.

[0081] Examples 5-9

[0082] Weigh the raw materials corresponding to each element in the alloy composition according to the molar percentage of the elements, and prepare the cast alloy ingot; the preparation method is the same as in Example 1.

[0083] The composition and room temperature tensile mechanical properties of Examples 5-9 are shown in Table 1.

[0084] Table 1. Composition and room temperature tensile mechanical properties of carbide-reinforced FCC / B2 dual-phase high-entropy alloys in Examples 5-9

[0085]

[0086]

[0087] As shown in Table 1, this invention achieves a strengthening effect similar to or even superior to that of transition metal strengthening elements by adding carbon to the alloy. Furthermore, the addition of carbon significantly reduces the alloy's density, thereby increasing its specific strength and promoting the development of lightweight engineering. Compared with existing technologies, this invention, while retaining the original FCC / B2 soft-hard two-phase structure, introduces high-density carbides and the interstitial atom strengthening effect of carbon through carbon alloying to strengthen the FCC phase. This reduces the strain distribution difference between the two phases during deformation, thereby improving the alloy strength without sacrificing plasticity.

[0088] Furthermore, controlling the Ti / C ratio not only introduces a finer-sized TiC strengthening phase into the alloy but also facilitates the refinement of Cr7C3 carbides. These multi-level carbide particles strengthen the matrix by hindering dislocation slip, while the smaller particle size prevents continuous crack propagation between carbides, thus achieving a synergistic improvement in the room-temperature strength and plasticity of the FCC / B2 dual-phase high-entropy alloy. The addition of V also helps to further refine the carbides, while the addition of Zr and B can play a role in solid solution strengthening and strengthening phase boundaries, providing a promising prospect for the alloy's application in high-temperature environments.

[0089] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A low-density carbide-reinforced FCC / B2 dual-phase high-entropy alloy, characterized in that, consists of, in terms of mole percentage: Al: 15-17 at.%, Cr: 10-12 at.%, Fe: 32-35 at.%, Ni: 34-36 at.%, Ti: 0.2-0.5 at.%, V: 0-0.1 at.%, Mn: 0-0.01 at.%, Zr: 0.01-0.03 at.%, B: 0.01-0.05 at.%, C: 2.5-4 at.%; 0.05≤Ti / C≤0.2; The FCC / B2 dual-phase high-entropy alloy comprises an FCC phase and a B2 phase, and the carbide strengthening phase comprises Cr7C3 and TiC carbides. The FCC / B2 dual-phase high-entropy alloy comprises an FCC phase and a B2 phase, and the carbide strengthening phase comprises Cr7C3 and TiC carbides. The tensile strength of the dual-phase high-entropy alloy at room temperature is greater than or equal to 1300 MPa, the elongation at break is greater than or equal to 10%, and the alloy density is less than or equal to 7.2 g / cm 3 .

2. The low-density carbide reinforced FCC / B2 dual-phase high-entropy alloy according to claim 1, wherein, The method comprises the following steps:

3. A method for preparing the low-density carbide reinforced FCC / B2 dual-phase high-entropy alloy according to claim 1, characterized in that, According to the target components, Ni, Fe, Cr, Al, Ti, and Fe-C alloy are weighed, ultrasonically cleaned with anhydrous ethanol, and then placed in a smelting furnace for smelting under an argon atmosphere. After pouring and cooling, a cast FCC / B2 dual-phase high-entropy alloy is obtained. The carbon content in the Fe-C alloy is 5-10 wt.%.

4. The method of producing a low-density carbide-reinforced FCC / B2 dual-phase high-entropy alloy according to claim 3, characterized in that, During the smelting process, the Ti ingot is first smelted at a current of 140-160 A; then the raw materials are smelted multiple times at a current of 200-220 A.

5. The method for preparing the low-density carbide-reinforced FCC / B2 dual-phase high-entropy alloy according to claim 3, characterized in that, The number of times of smelting the raw materials at a current of 200-220 A is ≥5, and each smelting lasts for 5 minutes.

6. The method for preparing the low-density carbide-reinforced FCC / B2 dual-phase high-entropy alloy according to claim 3, characterized in that, Electromagnetic stirring is added during the smelting process.

7. The method for preparing the low-density carbide-reinforced FCC / B2 dual-phase high-entropy alloy according to claim 3, characterized in that, The pouring process is based on copper mold pouring, and the arc gun current during pouring is 220-240 A.

8. The method for preparing the low-density carbide-reinforced FCC / B2 dual-phase high-entropy alloy according to claim 3, characterized in that, ​

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