Interstitial carbon induced light high-strength FCC / B2 eutectic multi-principal-element alloy and preparation method thereof

Abstract

The invention provides an interstitial carbon induced light high-strength FCC / B2 eutectic multi-principal-element alloy and a preparation method thereof, and relates to the technical field of novel metal materials. The interstitial carbon induced light high-strength FCC / B2 eutectic multi-principal-element alloy is prepared from the following components in percentage by mole: 17 to 18 at.% of Al, 10 to 13 at.% of Cr, 34 to 37 at.% of Fe, 34 to 37 at.% of Ni, 0.4 to 3.8 at.% of C, 0 to 0.15 at.% of N, 0 to 0.04 at.% of B and 0 to 0.04 at.% of Mn. A small amount or medium amount of carbon element is added into the FCC / B2 multi-principal-element alloy with hypereutectic components, and the eutectic multi-principal-element alloy with abundant microstructures is designed and prepared by utilizing interstitial carbon induced eutectic transformation. The alloy provided by the invention does not contain Co element with relatively high raw material cost, and the density is 1t; 7.2 g / cm < 3 > and the specific strength gt; and the elongation rate can reach 21.3% at most, so that the contradiction among low cost, light weight and high mechanical property of the eutectic multi-principal element alloy is solved.

Description

Technical Field

[0001] The present invention belongs to the technical field of novel metal materials, and relates to an interstitial carbon-induced lightweight and high-strength FCC / B2 eutectic multi-principal alloy and a preparation method thereof. Background Art

[0002] With the rapid development of the commercial aerospace industry, there is an urgent need to develop low-cost, lightweight, high-performance alloys to significantly reduce rocket manufacturing costs and fuel consumption. As a new branch of multi-principal alloys, eutectic multi-principal alloys have the advantages of both eutectic alloys and multi-principal alloys, and are the new multi-principal alloy system with the greatest potential for industrial application. Based on the pseudo-binary NiAl / (Co, Cr, Fe) eutectic framework, researchers have obtained a large number of eutectic multi-principal alloys with FCC / B2 two-phase structures, showing a relatively excellent combination of strength and plasticity. However, this type of alloy contains a large amount of Co element, and the price of Co raw materials reaches 18864-22370 USD / mt, which greatly increases the manufacturing cost of the alloy.

[0003] Recently, researchers are trying to develop Co-free Al-Cr-Fe-Ni eutectic multi-principal alloys to reduce the cost of industrial production. However, the strength and plasticity of most Co-free eutectic multi-principal alloys reported so far have not met expectations, because the lack of Co reduces the strain hardening ability of the material. In addition, Co-free Al-Cr-Fe-Ni based eutectic multi-principal alloys must contain a high proportion of Ni in a limited composition space, usually more than 40 at.%, such as AlCrFe 1.5 Ni 2.6 CrFeNi 2.2 Al 0.8 and AlCrFeNi 3 Alloy. This requirement makes lightweighting difficult. If lightweight Al or Cr is used to replace Ni, according to its phase selection criteria, the alloy will obtain a hypereutectic structure containing a large amount of primary B2 phase after solidification, which will significantly reduce its plasticity. This seems to have created an irreconcilable contradiction between low cost, lightweight and high performance. Therefore, how to expand the composition space of Al-Cr-Fe-Ni based eutectic multi-principal alloys and enhance their strength-plasticity synergy remains a huge challenge.

[0004] In order to solve the above contradiction, researchers have tried to introduce carbon elements into Al-Cr-Fe-Ni based multi-principal alloys with low Ni content for composition optimization. For example, the patent CN 118600301 A has been published. High-density carbides are introduced by adding a large amount of carbon elements, thereby achieving an improvement in alloy strength. However, the addition of a large amount of carbon elements causes the alloy composition to deviate seriously from the eutectic point. Therefore, the Al-Cr-Fe-Ni based multi-principal alloy obtained by this patent does not have a eutectic structure, thus losing its advantages in castability and strong plasticity. In comparison, this patent does not start from the perspective of carbides, but focuses on the role of interstitial carbon elements. By adding a small / medium amount of carbon elements, the eutectic transformation induced by interstitial carbon is used to achieve the transformation of FCC and B2 phases from hypereutectic to complete eutectic morphology, and a FCC / B2 multi-principal alloy with eutectic composition is prepared, which solves the long-standing problem of coordinated optimization of cost, density and mechanical properties of eutectic multi-principal alloys, and effectively promotes its practical application in rocket shell materials in the commercial aerospace field. Summary of the invention

[0005] The purpose of the present invention is to overcome the shortcomings of the above-mentioned prior art and to provide an interstitial carbon induced lightweight and high-strength FCC / B2 eutectic multi-principal component alloy and a preparation method thereof, aiming to solve the contradiction between low cost, light weight and high mechanical properties of FCC / B2 eutectic multi-principal component alloys in the prior art.

[0006] In order to achieve the above object, the present invention adopts the following technical solutions: A method for preparing an interstitial carbon-induced lightweight and high-strength FCC / B2 eutectic multi-principal alloy comprises the following steps: Step 1, weigh the corresponding alloy according to the set composition, Al: 17-18 at.%, Cr: 10-13 at.%, Fe: 34-37 at.%, Ni: 34-37 at.%, C: 0.4-3.8 at.%, N: 0-0.15 at.%, B: 0-0.04 at.%, Mn: 0-0.04 at.%; Step 2, arc melting the weighed alloy in a melting furnace to obtain a molten alloy; Step 3, pouring the molten alloy, the arc gun current used in the pouring process is 220-250A, to obtain a light and high-strength FCC / B2 eutectic multi-principal alloy; As the carbon content increases, the alloy structure changes from FCC / B2 hypereutectic to FCC / B2 complete eutectic, and then to FCC / B2 dual-phase dendrite and FCC / Cr 7 C 3 Eutectic, and finally transformed into B2 single-phase dendrite and FCC / Cr 7 C 3Eutectic.

[0007] A further improvement of the present invention is: Preferably, in step 2, during the arc melting process, the Ti ingot is first melted at a current of 150-170A, and then the alloy raw material is melted multiple times at a current of 210-230A.

[0008] Preferably, when the carbon content is 0.4-0.84 at.%, the pouring current is 220-230A; when the carbon content is ≥0.85 at.%, the pouring current is 230-250A.

[0009] Preferably, electromagnetic stirring is introduced during the smelting process.

[0010] An interstitial carbon-induced lightweight and high-strength FCC / B2 eutectic multi-principal alloy prepared by any of the above preparation methods, comprising, in molar percentage: Al: 17-18 at.%, Cr: 10-13 at.%, Fe: 34-37 at.%, Ni: 34-37 at.%, C: 0.4-3.8 at.%, N: 0-0.15 at.%, B: 0-0.04 at.%, Mn: 0-0.04 at.%; As the carbon content increases, the alloy structure changes from FCC / B2 hypereutectic to FCC / B2 complete eutectic, and then to FCC / B2 dual-phase dendrite and FCC / Cr 7 C 3 Eutectic, and finally transformed into B2 single-phase dendrite and FCC / Cr 7 C 3 Eutectic.

[0011] Preferably, in terms of molar percentage, it includes Al: 17-18 at.%, Cr: 11-12 at.%, Fe: 34-36 at.%, Ni: 35-37 at.%, C: 0.4-0.84 at.%, N: 0-0.1 at.%, B: 0-0.03 at.%, Mn: 0-0.02 at.%; The eutectic structure of the lightweight and high-strength FCC / B2 eutectic multi-principal alloy consists of FCC and B2 eutectic sheet layers.

[0012] Preferably, in terms of molar percentage, it includes Al: 17-18 at.%, Cr: 10-12 at.%, Fe: 34-36 at.%, Ni: 35-37 at.%, C: 2.93-3.73 at.%, N: 0-0.1 at.%, B: 0-0.03 at.%, Mn: 0-0.02 at.%; The eutectic structure of the lightweight and high-strength FCC / B2 eutectic multi-principal alloy is a dual-phase dendrite of FCC and B2, and the FCC dendrites and B2 dendrites are separated by FCC / Cr 7 C 3 The eutectic regions are separated.

[0013] Preferably, in terms of molar percentage, it includes Al: 17-18 at.%, Cr: 10-12 at.%, Fe: 34-36 at.%, Ni: 35-37 at.%, C: 3.74-3.8 at.%, N: 0-0.1 at.%, B: 0-0.03 at.%, Mn: 0-0.02 at.%; The microstructure of the lightweight and high-strength FCC / B2 eutectic multi-principal alloy is composed of B2 dendrites and FCC / Cr 7 C 3 Eutectic composition.

[0014] Preferably, the room temperature specific strength of the eutectic multi-principal alloy is >165 MPa cm -3 g -1 The maximum elongation at break is 21.3%, and the alloy density is <7.2 g / cm 3 .

[0015] Preferably, the structure of the FCC / B2 eutectic multi-principal alloy includes regular eutectic, dual-phase dendrite and carbide eutectic, the regular eutectic structure includes well-arranged lamellar eutectic and radial eutectic located on both sides of the lamellar eutectic, the dual-phase dendrite includes FCC dendrite and B2 dendrite, and the carbide eutectic is composed of FCC matrix and Cr 7 C 3 Carbide composition.

[0016] Compared with the prior art, the present invention has the following beneficial effects: 1. The present invention provides a method for preparing an interstitial carbon-induced lightweight high-strength FCC / B2 eutectic multi-principal alloy. When the multi-principal alloy is weighed and configured, the following molar percentage components are configured: Al: 17-18 at.%, Cr: 10-13 at.%, Fe: 34-37 at.%, Ni: 34-37 at.%, C: 0.4-3.8 at.%, N: 0-0.15 at.%, B: 0-0.04 at.%, Mn: 0-0.04 at.%. The present invention can transform a low-density Al-Cr-Fe-Ni-based hypereutectic alloy with a low Ni content into a complete eutectic alloy by adding an appropriate amount of carbon elements, thereby expanding the composition space of low-density eutectic multi-principal alloys. In addition, compared with the existing carbon-alloyed multi-principal alloy, the present invention removes some strong carbide-forming elements, such as Ti, V, etc., when designing the alloy composition, avoiding the formation of MC primary carbides, so that the carbon element exists in the form of interstitial carbon atoms. The present invention innovatively utilizes interstitial carbon atoms to effectively regulate the lattice mismatch between the FCC and B2 phases, thereby promoting the transformation from hypereutectic to eutectic and then to dual-phase dendrite structure, overcoming the shortcomings of high density and high cost of traditional FCC / B2 eutectic multi-principal component alloys.

[0017] 2. Taking into account the micro-uniformity of the eutectic solidification structure, the present invention accurately controls the size of the arc gun current according to the carbon content, which not only improves the casting quality of the alloy, but also effectively avoids the non-uniformity of the eutectic morphology and size in different regions of the ingot. In the present invention, when the carbon content is ≥0.85 at.%, the dendrite structure formed during solidification will hinder the flow of the melt, resulting in a decrease in fluidity. Therefore, it is necessary to increase the current to 230-250A to increase the flow rate of the melt and prevent the melt from forming faults during local solidification; eutectic alloys with a carbon content in the range of 0.4-0.84 at.% have better fluidity because they directly form eutectic sheet laminar structures. At this time, excessive pouring current will cause the melt to overheat and produce defects such as pores and gas inclusions. Therefore, a current of 220-230A is used for pouring during the pouring process.

[0018] 3. The eutectic multi-principal alloy obtained by the eutectic regulation of interstitial carbon in the present invention has excellent mechanical properties. Among them, the alloy with a carbon content of 0.43 at.% has a completely eutectic structure of FCC+B2, and the strength and plasticity are simultaneously improved through interstitial carbon solid solution strengthening and KS semi-coherent phase interface. Its performance and cost combination is better than almost all FCC / B2 eutectic multi-principal alloys at present; the alloy with a carbon content of 3.34 at.% exhibits a multi-level structure composed of FCC+B2 two-phase dendrites and carbide eutectics. Through the hindering effect of high-density carbides on dislocations and the strengthening of the alloy by the Orowan mechanism, its yield strength and tensile strength are extremely high. Most of the interstitial carbon-induced lightweight and high-strength FCC / B2 eutectic multi-principal alloys of the present invention have excellent casting performance, with a room temperature tensile strength exceeding or approaching 1200 MPa, and a maximum elongation at break of 21.3%. Large barrel sections can be quickly manufactured using ring welding and cold rolling forming technology. Compared with 304L stainless steel, the alloy in the present invention is 9% lighter, and the room temperature yield strength is increased by more than 2.5 times. In addition, the cost is reduced by 15-60% compared with the same type of eutectic multi-principal alloy. It meets the urgent needs of commercial aerospace for low-cost, low-density, high-performance materials, and has become a core competitor for the next generation of commercial aerospace rocket shell materials. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] Figure 1 Backscattered electron images of the multi-principal alloy provided for Example 1 and Comparative Example 1. Wherein, (a) is a low-magnification backscattered electron image of the alloy of Example 1; (b) is a high-magnification backscattered electron image of the alloy of Example 1; (c) is a low-magnification backscattered electron image of the alloy of Comparative Example 1; (d) is a high-magnification backscattered electron image of the alloy of Comparative Example 1.

[0020] Figure 2 Uniaxial tensile curves of the multi-principal component alloys provided in Example 1 and Comparative Example 1 at room temperature.

[0021] Figure 3 The specific tensile strength and raw material cost of the alloy of Example 1 are compared with other typical FCC / B2 eutectic multi-principal alloys.

[0022] Figure 4 The backscattered electron images of the multi-principal alloy provided in Example 2. Among them, (a) is a low-magnification backscattered electron image of the alloy in Example 2; (b) is a high-magnification backscattered electron image of the alloy in Example 2.

[0023] Figure 5 This is the uniaxial tensile curve of the multi-principal component alloy provided in Example 2 at room temperature.

[0024] Figure 6Backscattered electron images of the multi-principal element alloy provided for Example 3. Among them, (a) is the low-magnification backscattered electron image of the alloy in Example 3; (b) is the high-magnification backscattered electron image of the alloy in Example 3.

[0025] Figure 7 Uniaxial tensile curve of the multi-principal element alloy provided for Example 3 at room temperature.

[0026] Figure 8 Backscattered electron images of the multi-principal element alloy provided for Example 4. Among them, (a) is the low-magnification backscattered electron image of the alloy in Example 4; (b) is the high-magnification backscattered electron image of the alloy in Example 4.

[0027] Fig. 9 Uniaxial tensile curve of the multi-principal element alloy provided for Example 4 at room temperature. Detailed implementation manners

[0028] The technical solutions of the present invention will be further described in detail below in conjunction with the accompanying drawings and specific implementation manners: To enable those skilled in the art to understand the features and effects of the present invention, the following terms and phrases mentioned in the specification and claims will be generally described and defined. Unless otherwise specified, all technical and scientific terms used herein shall have the ordinary meaning understood by those skilled in the art for the present invention. In case of conflict, the definition in this specification shall prevail.

[0029] In this article, unless otherwise specified, "comprising", "including", "containing", "having" or similar terms cover the meanings of "consisting of" and "consisting essentially of". For example, "A comprises a" covers the meanings of "A comprises a and others" and "A consists only of a".

[0030] The present invention will be further described below in conjunction with specific embodiments. It should be understood that these embodiments are only used to illustrate the present invention and not to limit the scope of the present invention. In addition, it should be understood that after reading the content taught by the present invention, those skilled in the art can make various changes or modifications to the present invention, and these equivalent forms also fall within the scope defined by the appended claims of this application.

[0031] Conventional instrument equipment in the art is used in the following embodiments. For the experimental methods without specific conditions noted in the following embodiments, they are usually carried out under conventional conditions or according to the conditions recommended by the manufacturer. Various raw materials are used in the following embodiments. Unless otherwise stated, commercially available products are used, and their specifications are conventional specifications in the art. In the specification of the present invention and the following embodiments, unless otherwise specified, "%" represents weight percentage, "parts" represents weight parts, and the ratio represents weight ratio.

[0032] The first aspect of the present invention discloses a method for preparing an interstitial carbon-induced lightweight and high-strength FCC / B2 eutectic multi-principal alloy, comprising the following steps: First, the alloy composition is converted from atomic percentage to mass percentage. Based on the total mass of 40 g of the ingot, an analytical balance is used to accurately weigh metal elements such as Ni, Fe, Cr, Al and Fe-C intermediate alloy raw materials, and the weighing error of each raw material is within ±0.01 g. After that, all materials are placed in a copper crucible in an arc melting furnace. After argon circulation and gas washing, multiple smelting is carried out under the protection of high-purity argon. Finally, a water-cooled copper mold casting process is used to pour the alloy melt into a copper mold to obtain a size of 70×10×5 mm. 3 Plate-shaped cast specimens.

[0033] In some embodiments of the present invention, the elements Ni, Fe, Cr, Al, etc. are added using industrial-grade high-purity raw materials with a purity of ≥99.95 wt.%, and the carbon element is introduced in the form of Fe-C master alloy (carbon content 5-8 wt.%, the balance is Fe), which can achieve precise control of the carbon content. All raw materials must be ultrasonically cleaned and dried with anhydrous ethanol before smelting to remove surface impurities and ensure the stability of the final material structure and performance.

[0034] In some embodiments of the present invention, the smelting furnace is a non-consumable vacuum arc furnace.

[0035] In certain embodiments of the present invention, the raw materials are first placed in a vacuum arc melting furnace. Then, a mechanical pump is used to reduce the vacuum degree in the furnace to 3×10 0 Pa, and then use a molecular pump to further reduce the vacuum degree to 3×10 -3 After that, high-purity argon is filled to -0.05 MPa, and vacuum is drawn again to completely remove the oxygen in the furnace chamber. This process needs to be repeated twice to ensure the purity of the atmosphere.

[0036] In some embodiments of the present invention, before smelting the raw material, high-purity argon is again filled to -0.05 MPa as a protective gas. First, the Ti ingot is smelted at a current of 150-170 A for 10 minutes to further remove excess oxygen. Then, the raw material is continuously smelted at a current of 210-230 A for at least 5 times, and an electromagnetic stirring current of 1 A is turned on to promote the flow of the melt. Each smelting time is 5 minutes to enhance the uniformity of the composition.

[0037] In some embodiments of the present invention, the arc gun current is set to 220-250 A during the casting process, so that the alloy ingot quickly flows into the copper mold after melting, thereby ensuring the uniformity of the microstructure at different positions of the ingot.

[0038] Preferably, when the carbon content is 0.4-0.84 at.%, the pouring current is 220-230A.

[0039] Preferably, when the carbon content is ≥0.85 at.%, the pouring current is 230-250A.

[0040] The second aspect of the present invention discloses an interstitial carbon-induced lightweight high-strength FCC / B2 eutectic multi-principal alloy, which is composed of the following components in molar percentage: Al: 17-18 at.%, Cr: 10-13 at.%, Fe: 34-37 at.%, Ni: 34-37 at.%, C: 0.4-3.8 at.%, N: 0-0.15 at.%, B: 0-0.04 at.%, Mn: 0-0.04 at.%.

[0041] In some embodiments of the present invention, the interstitial carbon induced lightweight high-strength FCC / B2 eutectic multi-principal alloy consists of the following components in molar percentage: Al: 17-18 at.%, Cr: 11-12 at.%, Fe: 34-36 at.%, Ni: 35-37 at.%, C: 0.4-0.84 at.%, N: 0-0.1 at.%, B: 0-0.03 at.%, Mn: 0-0.02 at.%. Within this composition range, controlling the C content to 0.4-0.84 at.%, and the Al content to 17-18 at.%, can generate the target eutectic structure, which is composed of fine FCC+B2 eutectic crystal layers, thus giving the alloy excellent strength-plasticity combination, making it suitable for use as a rocket shell material.

[0042] In some embodiments of the present invention, the interstitial carbon induced lightweight high-strength FCC / B2 eutectic multi-principal alloy consists of the following components in molar percentage: Al: 17-18 at.%, Cr: 10-12 at.%, Fe: 34-36 at.%, Ni: 35-37 at.%, C: 2.93-3.73 at.%, N: 0-0.1 at.%, B: 0-0.03 at.%, Mn: 0-0.02 at.%. Within this composition range, controlling C to 2.93-3.73 at.% can form dual-phase dendrites of FCC and B2, and the FCC and B2 dendrites are separated by FCC / Cr between the dendrites. 7 C 3 The multi-layer structure makes the alloy stronger and less ductile, making it suitable for high stress bearing parts related to the aerospace field.

[0043] In some embodiments of the present invention, the interstitial carbon induced lightweight high-strength FCC / B2 eutectic multi-principal alloy consists of the following components in molar percentage: Al: 17-18 at.%, Cr: 10-12 at.%, Fe: 34-36 at.%, Ni: 35-37 at.%, C: 3.74-3.8 at.%, N: 0-0.1 at.%, B: 0-0.03 at.%, Mn: 0-0.02 at.%. The control of this composition range can induce the transformation of the eutectic structure to generate a B2 dendrite and FCC / Cr 7 C 3 The mixed phase structure composed of eutectic carbides has the lowest plasticity but the highest strength and is suitable for manufacturing cutting tools or wear-resistant parts.

[0044] The following is a further description with reference to specific embodiments.

[0045] Example 1 An interstitial carbon-induced light-weight high-strength FCC / B2 eutectic multi-principal alloy, comprising the following components in molar percentages: Al: 17 at.%, Cr: 12 at.%, Fe: 34.54 at.%, Ni: 36 at.%, C: 0.43 at.%, B: 0.01 at.%, Mn: 0.02 at.%; The carbide-reinforced FCC / B2 dual-phase multi-principal alloy is prepared according to the following steps: 1. Ingredients: Convert the molar percentage of the elements to mass percentage, based on the total mass of 40 g of the alloy ingot, accurately weigh the raw materials of each element with an analytical balance and control the error within ±0.01 g. Among them, Ni, Fe, Cr, Al, Ti and other elements are all industrial-grade high-purity raw materials with a purity of ≥99.95 wt.%, and carbon is added through Fe-C master alloy (carbon content 5-8wt.%).

[0046] 2. Melting: Put the weighed raw materials such as Ni, Fe, Cr, Al, Fe-C alloy into the copper crucible of the non-consumable vacuum arc furnace, and evacuate the cavity of the arc melting furnace to 3×10 -3 Pa, and then high-purity argon was filled to -0.05 MPa as a protective gas, and this step was repeated twice to exclude oxygen; then the Ti ingot was melted with a current set to 170 A to further remove excess oxygen; the raw material was melted continuously for 5 times with a current set to 220 A, each melting time was 5 minutes, and at the same time, a 1A electromagnetic stirring current was turned on to promote melt flow.

[0047] 3. Pouring: Place the obtained alloy round ingot on top of the copper mold, adjust the arc gun current to 220 A to quickly melt the alloy and allow the alloy melt to quickly flow into the copper mold. After the alloy ingot cools, take out the copper mold to obtain a 70×10×5 mm 3 Plate-shaped cast multi-principal alloy sample.

[0048] Comparative Example 1 Al: 17 at.%, Cr: 12 at.%, Fe: 34.96 at.%, Ni: 36 at.%, B: 0.02 at.%, Mn: 0.02at.%.

[0049] The preparation method is the same as Example 1.

[0050] Figure 1 The microstructure pictures are of the interstitial carbon induced lightweight and high-strength FCC / B2 eutectic multi-principal element alloy of Example 1 and the alloy of Comparative Example 1. The microstructure of the alloy of Example 1 is a regular eutectic composed of FCC and B2 phases, including well-arranged lamellar eutectics and radial eutectics located on both sides of the lamellar eutectics. No carbide phase was observed in the entire microstructure, confirming that carbon mainly exists in the form of interstitial carbon atoms. In addition, the eutectic structure of the alloy is extremely uniform, and no primary phase was found. In contrast, the alloy in Comparative Example 1 has a typical hypereutectic structure, which is composed of relatively coarse B2 primary dendrites and irregular eutectics between dendrites. This organizational feature is not conducive to improving the plasticity of the alloy. Figure 2 The tensile engineering stress-strain curves at room temperature for the interstitial carbon-induced lightweight high-strength FCC / B2 eutectic multi-principal alloy of Example 1 and the alloy of Comparative Example 1. The carbon element in the alloy of Example 1 can be dissolved in the lattice of the FCC phase in the form of interstitial carbon, thereby inducing solid solution strengthening. In addition, the large amount of KS eutectic interfaces in the alloy of Example 1 can introduce significant interface strengthening and back stress strengthening effects, giving the alloy excellent mechanical properties. It can be seen that the yield strength of the alloy of Example 1 is 536 MPa, the tensile strength is 1211 MPa, and the elongation is as high as 21.3%. In addition, the density of the alloy is only 7.19 g / cm 3 The yield strength of the alloy without carbon in Comparative Example 1 is 506 MPa, the tensile strength is 1190 MPa, and the elongation at break is severely reduced to 13.9%.

[0051] Figure 3 The specific tensile strength and raw material cost of the alloy of Example 1 are compared with other typical FCC / B2 eutectic multi-principal alloys. It can be seen that the specific tensile strength of the alloy of Example 1 is as high as 168 MPa cm -3 g -1, and also has a low raw material cost of 8.83 USD / Kg. Therefore, this low-cost, lightweight and high-strength carbon alloyed FCC / B2 eutectic multi-principal alloy has broad industrial application prospects.

[0052] Example 2 A light-weight and high-strength FCC / B2 eutectic multi-principal alloy induced by interstitial carbon, the preparation method of the multi-principal alloy is the same as the preparation method of Example 1, except that the pouring current is 230A, and the amount of raw materials is weighed according to the following molar percentage components: Al: 17 at.%, Cr: 12 at.%, Fe: 34 at.%, Ni: 36 at.%, C: 0.85 at.%, N: 0.1 at.%, B: 0.03 at.%, Mn: 0.02 at.%.

[0053] The preparation method is the same as Example 1.

[0054] The microstructure of the alloy of Example 2 is as follows Figure 4 As shown in Figure 2, it can be seen that the alloy of Example 2 has a mixed microstructure composed of regular eutectic and abnormal eutectic. In addition, it can be observed from the high-magnification image that the Cr 7 C 3 Carbides. These carbides weaken the bonding strength of the eutectic boundaries, resulting in a decrease in the alloy's work hardening ability and ductility. Figure 5 The tensile engineering stress-strain curve of the alloy of Example 2 shows that its yield strength is 566 MPa, the tensile strength is 1153 MPa, and the elongation at break is 17.0%. The tensile strength and elongation of Example 2 are lower than those of Example 1, indicating that the formation of abnormal eutectic and interface carbides is not conducive to the continuous deformation of the alloy. Therefore, in order to prepare a multi-principal alloy with regular eutectic and excellent comprehensive mechanical properties, the content of carbon element needs to be carefully controlled below 0.85 at%.

[0055] Example 3 A light-weight and high-strength FCC / B2 eutectic multi-principal alloy induced by interstitial carbon, the preparation method of the multi-principal alloy is the same as the preparation method of Example 1, except that the pouring current is 250A, and the amount of raw materials is weighed according to the following molar percentage components: Al: 17 at.%, Cr: 10 at.%, Fe: 34.64 at.%, Ni: 35 at.%, C: 3.34 at.%, B: 0.01 at.%, Mn: 0.01 at.%.

[0056] Figure 6The microstructure image of the interstitial carbon-induced lightweight high-strength FCC / B2 eutectic multi-principal alloy obtained in Example 3. It can be seen that the alloy in Example 3 has a more complex microstructure, which is mainly composed of dual-phase dendrites of FCC and B2, and the FCC and B2 dendrites are separated by Cr between the dendrites. 7 C 3 The carbide eutectic regions are separated to form a multi-level eutectic microstructure. Figure 7 The tensile engineering stress-strain curve of the alloy obtained in Example 3. Due to the significant strengthening effect of high-density carbides, the yield strength and tensile strength of the alloy in Example 3 reached 608 MPa and 1285 MPa respectively, and the elongation at break was maintained at 12.1%. The density of the alloy is only 7.15 g / cm 3 , with a specific tensile strength of up to 179 MPa cm -3 g -1 , further demonstrating the effectiveness of the interstitial carbon induced lightweight and high-strength FCC / B2 eutectic multi-principal component alloy design strategy.

[0057] Example 4 A light-weight and high-strength FCC / B2 eutectic multi-principal alloy induced by interstitial carbon, the preparation method of the multi-principal alloy is the same as the preparation method of Example 1, except that the pouring current is 240A, and the amount of raw materials is weighed according to the following molar percentage components: Al: 17 at.%, Cr: 10 at.%, Fe: 34.24 at.%, Ni: 35 at.%, C: 3.74 at.%, B: 0.01 at.%, Mn: 0.01 at.%.

[0058] Figure 8 The microstructure image of the interstitial carbon-induced lightweight high-strength FCC / B2 eutectic multi-principal alloy obtained in Example 4. It can be found that the alloy in Example 4 is composed of B2 primary phase and FCC / Cr 7 C 3 Eutectic phase composition. Among them, the B2 phase still shows a typical dendrite morphology, while the FCC dendrite disappears, and the eutectic carbides are distributed in the FCC matrix in the form of rods. Fig. 9 This is the tensile engineering stress-strain curve of the multi-principal alloy obtained in Example 4. The yield strength and tensile strength of the alloy are as high as 678 MPa and 1322 MPa respectively, and the elongation is 8.6%.

[0059] Embodiment 5-10 The raw materials corresponding to each element in the alloy component are weighed according to the molar percentage of the element, and the preparation method is the same as that in Example 1.

[0060] The compositions and room temperature tensile mechanical properties of Examples 5-10 are shown in Table 1.

[0061] Table 1 Composition and tensile mechanical property data of lightweight and high-strength FCC / B2 eutectic multi-principal element alloys induced by interstitial carbon in Examples 5-10

[0062] It can be seen from Table 1 that the present invention removes strong carbide-forming elements such as Ti and V, fundamentally inhibits the precipitation of primary carbides, and promotes the existence of carbon elements in the form of interstitial carbon atoms in the initial stage of solidification. By utilizing the difference in the solubility of interstitial carbon in the FCC and B2 phases, the lattice misfit between the FCC and B2 phases can be effectively regulated, thereby affecting the nucleation and growth modes of the eutectic. Based on this, by precisely regulating the principal element ratio, carbon content, and pouring current in the multi-principal element FCC / B2 dual-phase system, a lightweight, high-strength, and low-cost eutectic multi-principal element alloy has been successfully designed and prepared. This interstitial-carbon-induced eutectic microstructure design strategy breaks through the composition design constraints of traditional FCC / B2 multi-principal element alloys and opens up a new paradigm for the synergistic optimization of cost-density-performance in new eutectic alloy systems.

[0063] The above are only the preferred embodiments of the present invention and are not intended to limit the present invention. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principles of the present invention shall be included within the protection scope of the present invention.

Claims

1. A method for preparing a light-weight and high-strength FCC / B2 eutectic multi-principal alloy induced by interstitial carbon, characterized in that: The following steps are involved: Step 1, according to the set composition, Al: 17-18 at.%, Cr: 10-13 at.%, Fe: 34-37 at.%, Ni: 34-37 at.%, C: 0.4-3.8 at.%, N: 0-0.15 at.%, B: 0-0.04 at.%, Mn: 0-0.04 at.%, weigh the corresponding alloy raw materials; Step 2, arc melting the weighed alloy raw materials in a melting furnace to obtain a molten alloy; Step 3, pouring the molten alloy, the arc gun current used in the pouring process is 220-250A, to obtain a light and high-strength FCC / B2 eutectic multi-principal alloy; With the increase of carbon content, the alloy structure changes from FCC / B2 hypereutectic to FCC / B2 complete eutectic, then to FCC / B2 two-phase dendrite and FCC / Cr7C3 eutectic, and finally to B2 single-phase dendrite and FCC / Cr7C3 eutectic.

2. The method for preparing a light-weight and high-strength FCC / B2 eutectic multi-principal alloy induced by interstitial carbon according to claim 1, characterized in that: In step 2, during the arc melting process, the Ti ingot is first melted at a current of 150-170A, and then the alloy raw material is melted multiple times at a current of 210-230A.

3. The method for preparing a light-weight and high-strength FCC / B2 eutectic multi-principal alloy induced by interstitial carbon according to claim 1, characterized in that: When the carbon content is 0.4-0.84 at.%, the pouring current is 220-230A; when the carbon content is ≥0.85 at.%, the pouring current is 230-250A.

4. The method for preparing a light-weight and high-strength FCC / B2 eutectic multi-principal alloy induced by interstitial carbon according to claim 1, characterized in that: In step 2, electromagnetic stirring is introduced during the smelting process.

5. An interstitial carbon-induced lightweight high-strength FCC / B2 eutectic multi-principal alloy prepared by the preparation method according to any one of claims 1 to 4, characterized in that: In mole percentage, include: Al: 17-18 at.%, Cr: 10-13 at.%, Fe: 34-37 at.%, Ni: 34-37 at.%, C: 0.4-3.8 at.%, N: 0-0.15 at.%, B: 0-0.04 at.%, Mn: 0-0.04at.%; With the increase of carbon content, the alloy structure changes from FCC / B2 hypereutectic to FCC / B2 complete eutectic, then to FCC / B2 two-phase dendrite and FCC / Cr7C3 eutectic, and finally to B2 single-phase dendrite and FCC / Cr7C3 eutectic.

6. The interstitial carbon induced lightweight high-strength FCC / B2 eutectic multi-principal alloy according to claim 5, characterized in that: In terms of mole percentage, it includes Al: 17-18 at.%, Cr: 11-12 at.%, Fe: 34-36 at.%, Ni: 35-37 at.%, C: 0.4-0.84 at.%, N: 0-0.1 at.%, B: 0-0.03 at.%, Mn: 0-0.02 at.%; The eutectic structure of the lightweight and high-strength FCC / B2 eutectic multi-principal alloy consists of FCC and B2 eutectic sheet layers.

7. The interstitial carbon induced lightweight high-strength FCC / B2 eutectic multi-principal alloy according to claim 5, characterized in that: In terms of mole percentage, it includes Al: 17-18 at.%, Cr: 10-12 at.%, Fe: 34-36 at.%, Ni: 35-37 at.%, C: 2.93-3.73 at.%, N: 0-0.1 at.%, B: 0-0.03 at.%, Mn: 0-0.02 at.%; The eutectic structure of the lightweight and high-strength FCC / B2 eutectic multi-principal alloy presents a two-phase dendrite morphology of FCC and B2, and the FCC dendrites and B2 dendrites are separated by the FCC / Cr7C3 eutectic region between the dendrites.

8. The interstitial carbon induced lightweight high-strength FCC / B2 eutectic multi-principal alloy according to claim 5, characterized in that: In terms of mole percentage, it includes Al: 17-18 at.%, Cr: 10-12 at.%, Fe: 34-36 at.%, Ni: 35-37 at.%, C: 3.74-3.8 at.%, N: 0-0.1 at.%, B: 0-0.03 at.%, Mn: 0-0.02 at.%; The microstructure of the lightweight and high-strength FCC / B2 eutectic multi-principal alloy consists of B2 dendrites and FCC / Cr7C3 eutectics.

9. The interstitial carbon induced lightweight high-strength FCC / B2 eutectic multi-principal alloy according to claim 5, characterized in that: The room temperature specific strength of the eutectic multi-principal alloy is >165 MPa cm -3 g -1 , the maximum elongation at break is 21.3%, and the alloy density is <7.2 g / cm 3 .

10. The interstitial carbon induced lightweight high-strength FCC / B2 eutectic multi-principal alloy according to claim 5, characterized in that: The microstructure of the FCC / B2 eutectic multi-principal alloy includes regular eutectics, dual-phase dendrites and carbide eutectics. The regular eutectic structure includes well-arranged lamellar eutectics and radial eutectics located on both sides of the lamellar eutectics. The dual-phase dendrites include FCC dendrites and B2 dendrites. The carbide eutectics are composed of FCC matrix and Cr7C3 carbide.

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