Carbide-based eutectic medium-entropy alloy and preparation method thereof

Abstract

The chemical component of the carbide-based eutectic medium-entropy alloy is CrFeNi (NbC) x, x is larger than or equal to 0.1 and smaller than or equal to 0.3, the carbide-based eutectic medium-entropy alloy is prepared through a vacuum arc melting method, and after vacuum arc melting, the solidification phase of the carbide-based eutectic medium-entropy alloy is FCC, MC carbide and M7C3 carbide; and when x is equal to 0.1, the solidification structure of the alloy is primary FCC + reticular eutectic FCC / MC + superfine eutectic FCC / M7C3. When x is equal to 0.2-0.3, the solidification structure of the alloy is primary MC + primary FCC + reticular eutectic FCC / MC + superfine eutectic FCC / M7C3; the Vickers hardness of the alloy ranges from 235.6 HV to 287.0 HV, the yield strength of the alloy ranges from 439 MPa to 534 MPa, and the compressive strength (Rpc30) of the alloy under the specified strain (30%) ranges from 1482 MPa to 1607 MPa.

Description

Technical Field

[0001] This invention belongs to the field of multi-principal element alloys, and relates to medium-entropy alloys and their preparation methods, specifically to a carbide-based eutectic medium-entropy alloy and its preparation method. Background Technology

[0002] In recent years, multi-principal element alloy materials have attracted much attention in the materials science community. Among them, medium-entropy alloys have shown great application potential in engineering fields due to their high strength, high hardness, high wear resistance, high corrosion resistance, and excellent high-temperature stability. However, these alloys still have obvious shortcomings: firstly, it is difficult to achieve both high strength and high ductility, making it difficult to meet the stringent requirements for comprehensive mechanical properties in some applications; secondly, because the alloy system contains multiple metallic elements, problems such as poor melt fluidity and component segregation are prone to occur during the smelting process, making the preparation of large-size ingots extremely difficult and severely restricting their industrial application.

[0003] Yu et al. used Al of single-phase FCC 0.2 Using a CoCrFeNi high-entropy alloy as the matrix, the addition of WC, SiC, and TiC particles significantly improved the mechanical properties and wear resistance of the alloy, with the 15 vol.% TiC composite exhibiting the best wear resistance. Gu et al. prepared Fe using arc melting. 49.5 Mn 30 Co 10 Cr 10 X 0.5 In a high-entropy alloy (X=B4C, ZrC and TiC), it was found that carbide ceramic particles can refine the matrix grains and stabilize the FCC phase, thus effectively improving the strength and toughness of the alloy.

[0004] However, the aforementioned existing technical solutions rely on the addition of ceramic particles to enhance performance, and do not start from the perspective of multi-element eutectic microstructure design of eutectic medium-entropy alloys. Therefore, they still cannot fundamentally solve the core technical problem of balancing strength and plasticity and ease of casting in medium-entropy alloys. Summary of the Invention

[0005] To address the shortcomings of existing technologies, the present invention aims to provide a carbide-based eutectic medium-entropy alloy and its preparation method, which exhibits good strength-toughness matching and comprehensive mechanical properties.

[0006] To achieve the above objectives, the present invention employs the following technical solution: A carbide-based eutectic medium-entropy alloy with the general chemical formula CrFeNi(NbC). x In the formula, 0.1≤x≤0.3.

[0007] This invention also protects a method for preparing the carbide-based eutectic medium-entropy alloy as described above, comprising the following steps: Step 1: Place pure metallic elements Cr, Fe, Ni, and Nb into anhydrous ethanol, clean them with ultrasonic waves, and dry them to obtain pretreated metallic elements Cr, Fe, Ni, and Nb. Step 2, according to the general chemical formula CrFeNi(NbC) x Pretreated pure metallic elements Cr, Fe, Ni, Nb, and iron-carbon particles were weighed separately, wherein: 0.1≤x≤0.3, and the carbon content in the iron-carbon particles was 30 wt.%. Step 3: Following the order of melting points from low to high, place the weighed elemental metals Cr, Fe, Ni, Nb, and iron-carbon particles from Step 2 into a water-cooled crucible within a vacuum non-consumable arc furnace. Evacuate the vacuum non-consumable arc furnace to a vacuum level of 3 × 10⁻⁶. - After 3 Pa, vacuum arc melting begins, and the raw materials are completely melted to form an alloy ingot. Step 4: Turn the ingot over and remelt it. Repeat the remelting process 5 times. Finally, cool it to room temperature in the furnace to obtain a carbide-based eutectic medium-entropy alloy.

[0008] Preferably, the purity of the metallic elements Cr, Ni, and Nb in step 1 is 99.95%, and the purity of the iron-carbon particles and metallic element Fe is 99.9%.

[0009] Preferably, the ultrasonic cleaning time in step 1 is 15-20 minutes.

[0010] Preferably, the process of evacuating the vacuum non-consumable arc melting furnace in step 3 is as follows: first, the vacuum level inside the vacuum non-consumable arc melting furnace is evacuated to 3×10⁻⁶. -3 ~6×10 -3 Pa, then fill with argon gas until the internal pressure is 0.05 Pa, repeat this process 3 times, and then evacuate to a vacuum level of 3 × 10 Pa. -3 ~6×10 -3 Pa.

[0011] Preferably, in step 3, another water-cooled crucible in the vacuum non-consumable arc melting furnace contains elemental Ti for removing residual oxygen.

[0012] Preferably, the vacuum arc melting described in step 3 is carried out under electromagnetic stirring.

[0013] This invention also protects a carbide-based eutectic medium-entropy alloy prepared by the method described above, wherein the solidified phases are FCC, MC carbide and M7C3 carbide, wherein MC is NbC carbide and M7C3 is Cr-rich carbide.

[0014] Furthermore, when x=0.1, the solidification structure of the alloy is primary FCC+, network eutectic FCC / MC+, and ultrafine eutectic FCC / M7C3; When x = 0.2~0.3, the solidification structure of the alloy is primary MC+, primary FCC+, network eutectic FCC / MC+, and ultrafine eutectic FCC / M7C3.

[0015] Furthermore, at room temperature, the yield strength is 439~534 MPa, the compressive strength at 30% strain is 1482~1607 MPa, and the Vickers hardness is 235.6~287 HV.

[0016] Compared with the prior art, the present invention has the following technical effects: The carbide-based eutectic medium-entropy alloy provided by this invention is based on low-cost Cr, Fe, Ni and Nb, and introduces C element to form a eutectic structure. It is not only low in cost, but also has the effect of coordinating and enhancing mechanical properties, giving the medium-entropy alloy excellent comprehensive mechanical properties. The carbide-based eutectic medium-entropy alloy provided by this invention maintains a strain greater than 50% at room temperature without fracture, retains good alloy strength under excellent plasticity conditions, has good yield strength and hardness, and exhibits excellent comprehensive mechanical properties. It has potential engineering application value, and the preparation method is simple, allowing for the casting of large-sized and complex-shaped workpieces, thus broadening its practical applications in different engineering fields. Attached Figure Description

[0017] Figure 1 The XRD patterns of the eutectic medium-entropy alloys prepared in Examples 1 to 3 of this invention are shown below. Figure 2 The low-magnification and high-magnification SEM structures of the eutectic medium-entropy alloys prepared in Examples 1 to 3 of this invention are shown. Figure 3 The figures are the room temperature compressive stress-strain curves of the eutectic medium-entropy alloys prepared in Examples 1 to 3 of this invention at a specified strain. Figure 4 The mechanical properties of the eutectic medium entropy alloys prepared in Examples 1 to 3 of this invention are statistically shown. Detailed Implementation

[0018] The following detailed explanation of the specific content of the present invention is provided in conjunction with embodiments. These descriptions are intended to explain the present invention and not to limit it.

[0019] The present invention will be further described in detail below with reference to specific embodiments. These descriptions are for explanation purposes only and are not intended to limit the scope of the invention.

[0020] The iron-carbon particles of this invention are produced by Beijing Yanbang Materials Technology Co., Ltd., named Iron-Carbon 30 wt% Particles, with a purity of 99.9%, a size of 3~15 mm, and a production date of 2025101.

[0021] The metallic elements Cr, Ni, and Nb of this invention are Cr sheets, Ni blocks, and Nb blocks with a purity of 99.95%, respectively, and the metallic element Fe has a purity of 99.9%, with a size of 3~15 mm.

[0022] Example 1 Step 1: Place the high-purity metals Cr, Ni, Nb, and Fe into anhydrous ethanol and ultrasonically clean for 15 min, then dry them with a hair dryer to obtain pretreated elemental metals Cr, Fe, Ni, and Nb. Step 2, according to the chemical formula CrFeNi(NbC) 0.1 Weigh out the pretreated metallic elements Cr, Fe, Ni, Nb, and iron-carbon particles. Step 3: Place the weighed elemental metals and iron-carbon particles in a water-cooled crucible for non-consumable arc melting in order of increasing melting point. Place metallic Ti (Ti) in another water-cooled crucible in the non-consumable arc melting furnace to remove residual oxygen. Evacuate the furnace to a vacuum level of 3 × 10⁻⁶. -3 Pa, then high-purity argon gas was injected into the furnace until the internal pressure was 0.05 Pa, and this was repeated 3 times before the vacuum was evacuated to 3 × 10 Pa. -3 Pa; Step 4: Under electromagnetic stirring, melting begins at a maximum melting current of 600A and a melting voltage of approximately 380V. After the raw materials are completely melted, an alloy ingot is formed. The alloy ingot is then flipped and remelted 5 times before being cooled to room temperature in the furnace and removed to obtain CrFeNi(NbC). 0.1 Eutectic medium entropy alloy.

[0023] Example 2 Step 1: Place the high-purity metals Cr, Ni, Nb, and Fe into anhydrous ethanol and ultrasonically clean for 18 min, then dry them with a hair dryer to obtain pretreated elemental metals Cr, Fe, Ni, and Nb. Step 2, according to the chemical formula CrFeNi(NbC) 0.2 Weigh out the pretreated metallic elements Cr, Fe, Ni, Nb, and iron-carbon particles. Step 3: Place the weighed elemental metals and iron-carbon particles in a water-cooled crucible for non-consumable arc melting in order of increasing melting point. Place metallic Ti (Ti) in another water-cooled crucible in the non-consumable arc melting furnace to remove residual oxygen. Evacuate the furnace to a vacuum level of 5 × 10⁻⁶. -3 Pa, then high-purity argon gas was injected into the furnace until the internal pressure was 0.05 Pa, and this was repeated 3 times before the vacuum was evacuated to 5 × 10 Pa. -3 Pa; Step 4: Under electromagnetic stirring, melting begins at a maximum melting current of 600A and a melting voltage of approximately 380V. After the raw materials are completely melted, an alloy ingot is formed. The alloy ingot is then flipped and remelted 5 times before being cooled to room temperature in the furnace and removed to obtain CrFeNi(NbC). 0.2 Eutectic medium entropy alloy.

[0024] Example 3 Step 1: Place the high-purity metals Cr, Ni, Nb, and Fe into anhydrous ethanol and ultrasonically clean for 20 min, then dry them with a hair dryer to obtain pretreated elemental metals Cr, Fe, Ni, and Nb. Step 2, according to the chemical formula CrFeNi(NbC) 0.3 Weigh out the pretreated metallic elements Cr, Fe, Ni, Nb, and iron-carbon particles. Step 3: Place the weighed elemental metals and iron-carbon particles in a water-cooled crucible for non-consumable arc melting in order of increasing melting point. Place metallic Ti (Ti) in another water-cooled crucible in the non-consumable arc melting furnace to remove residual oxygen. Evacuate the furnace to a vacuum level of 6 × 10⁻⁶. -3 Pa, then high-purity argon gas was injected into the furnace until the internal pressure was 0.05 Pa, and this was repeated 3 times before the vacuum was evacuated to 6 × 10 Pa. -3 Pa; Step 4: Under electromagnetic stirring, melting begins at a maximum melting current of 600A and a melting voltage of approximately 380V. After the raw materials are completely melted, an alloy ingot is formed. The alloy ingot is then flipped and remelted 5 times before being cooled to room temperature in the furnace and removed to obtain CrFeNi(NbC). 0.3 Eutectic medium entropy alloy.

[0025] Table 1. Room temperature mechanical properties of eutectic medium-entropy alloy FeCrNi(NbC)x (0.1≤x≤0.3) As can be clearly seen from Table 1, the eutectic medium entropy alloys prepared in Examples 1 to 3 not only have extremely high toughness and plasticity, but also exhibit good yield strength and compressive strength.

[0026] Figure 1The XRD patterns of the eutectic medium-entropy alloys prepared in Examples 1 to 3 of this invention are shown. The samples exhibit a series of sharp characteristic peaks at 2θ = 43.6°, 50.8°, and 74.7°, corresponding to the diffraction of the (111), (200), and (220) crystal planes, respectively, and highly coincide with the characteristic peaks of FCC. The samples also exhibit a series of sharp characteristic peaks at 2θ = 40.6°, 50.4°, 69.6°, and 87.2°, corresponding to the diffraction of the (102), (402), (403), and (313) crystal planes, respectively, and highly coincide with the characteristic peaks of M7C3. Furthermore, the samples exhibit a series of sharp characteristic peaks at 2θ = 34.7°, 40.3°, 58.3°, and 69.7°, corresponding to the diffraction of the (111), (200), (220), and (311) crystal planes, respectively, and highly coincide with the characteristic peaks of MC.

[0027] Figure 2 The low-magnification and high-magnification SEM structures of the eutectic medium-entropy alloys prepared in Examples 1 to 3 of this invention are shown; wherein, Figure 2 a and Figure 2 a1 shows the low-magnification and high-magnification SEM structures of the eutectic medium-entropy alloy prepared in Example 1, such as... Figure 2 a and Figure 2 As shown in a1: the solidification structure of the alloy is primary FCC+, network eutectic FCC / MC+ and ultrafine eutectic FCC / M7C3; Figure 2 b and Figure 2 b1 shows the low-magnification and high-magnification SEM structures of the eutectic medium-entropy alloy prepared in Example 2. Figure 2 c and Figure 2 c1 shows the low-magnification and high-magnification SEM structures of the eutectic medium-entropy alloy prepared in Example 3, such as... Figure 2 b、 Figure 2 b1、 Figure 2 c. Figure 2 As shown in c1, the solidification structure of the alloy consists of primary MC, primary FCC+, network eutectic FCC / MC+, and ultrafine eutectic FCC / M7C3.

[0028] Figure 3 The figures show the room temperature compressive stress-strain curves of the eutectic medium-entropy alloys prepared in Examples 1-3 of this invention at a specified strain; CrFeNi(NbC). 0.1 CrFeNi(NbC) 0.2 CrFeNi(NbC) 0.3 The yield strengths are 439 MPa, 450 MPa, and 534 MPa, respectively. The compressive strength (R) of the three alloys under a specified strain (30%) is... pc30 The values ​​are 1482 MPa, 1484 MPa, and 607 MPa, respectively.

[0029] Figure 4The above is a statistical chart of the mechanical properties of the eutectic medium-entropy alloys prepared in Examples 1-3 of this invention; at room temperature, the Vickers hardness of the alloy is 235.6-287.0 HV, the yield strength is 439-534 MPa, and the compressive strength (R) of the alloy under a specified strain (30%) is... pc30 The pressure ranges from 1482 to 1607 MPa.

[0030] The above embodiments are only used to illustrate the technical solutions of the present invention and not to limit it. Although the present invention has been described in detail with reference to the above embodiments, those skilled in the art can still make modifications or equivalent substitutions to the specific implementation of the present invention. Any modifications or equivalent substitutions that do not depart from the spirit and scope of the present invention are within the protection scope of the claims of the present invention pending approval.

Claims

1. A carbide-based eutectic medium-entropy alloy, characterized in that, The general chemical formula is CrFeNi(NbC). x In the formula, 0.1≤x≤0.

3.

2. A method for preparing a carbide-based eutectic medium-entropy alloy as described in claim 1, characterized in that, Includes the following steps: Step 1: Place pure metallic elements Cr, Fe, Ni, and Nb into anhydrous ethanol, clean them with ultrasonic waves, and dry them to obtain pretreated metallic elements Cr, Fe, Ni, and Nb. Step 2, according to the general chemical formula CrFeNi(NbC) x Pretreated pure metallic elements Cr, Fe, Ni, Nb, and iron-carbon particles were weighed separately, wherein: 0.1≤x≤0.3, and the carbon content in the iron-carbon particles was 30 wt.%. Step 3: Following the order of melting points from low to high, place the weighed elemental metals Cr, Fe, Ni, Nb, and iron-carbon particles from Step 2 into a water-cooled crucible within a vacuum non-consumable arc furnace. Evacuate the vacuum non-consumable arc furnace to a vacuum level of 3 × 10⁻⁶. - After 3 Pa, vacuum arc melting begins, and the raw materials are completely melted to form an alloy ingot. Step 4: Turn the ingot over and remelt it. Repeat the remelting process 5 times. Finally, cool it to room temperature in the furnace to obtain a carbide-based eutectic medium-entropy alloy.

3. The method for preparing a carbide-based eutectic medium-entropy alloy as described in claim 2, characterized in that, The purity of the metallic elements Cr, Ni, and Nb mentioned in step 1 is 99.95%, and the purity of the iron-carbon particles and metallic element Fe is 99.9%.

4. The method for preparing a carbide-based eutectic medium-entropy alloy as described in claim 2, characterized in that, The ultrasonic cleaning time described in step 1 is 15-20 minutes.

5. The method for preparing a carbide-based eutectic medium-entropy alloy as described in claim 2, characterized in that, The process of evacuating the vacuum non-consumable arc melting furnace described in step 3 is as follows: First, the vacuum level inside the vacuum non-consumable arc melting furnace is evacuated to 3×10⁻⁶. -3 ~6×10 -3 Pa, then fill with argon gas until the internal pressure is 0.05 Pa, repeat this process 3 times, and then evacuate to a vacuum level of 3 × 10 Pa. -3 .

6. The method for preparing a carbide-based eutectic medium-entropy alloy as described in claim 2, characterized in that, In step 3, another water-cooled crucible in the vacuum non-consumable arc melting furnace contains elemental Ti for removing residual oxygen.

7. The method for preparing a carbide-based eutectic medium-entropy alloy as described in claim 2, characterized in that, The vacuum arc melting described in step 3 is carried out under electromagnetic stirring.

8. A carbide-based eutectic medium-entropy alloy prepared by the method according to any one of claims 2 to 7, characterized in that, The solidified phase consists of FCC, MC carbides and M7C3 carbides, where MC is an NbC carbide and M7C3 is a Cr-rich carbide.

9. The carbide-based eutectic medium-entropy alloy as described in claim 8, characterized in that, When x=0.1, the solidification structure of the alloy is primary FCC+, network eutectic FCC / MC+, and ultrafine eutectic FCC / M7C3; When x = 0.2~0.3, the solidification structure of the alloy is primary MC+, primary FCC+, network eutectic FCC / MC+, and ultrafine eutectic FCC / M7C3.

10. The carbide-based eutectic medium-entropy alloy as described in claim 8, characterized in that, At room temperature, the yield strength is 439~534 MPa, the compressive strength at 30% strain is 1482~1607 MPa, and the Vickers hardness is 235.6~287 HV.

Images