Laves phase reinforced heat-corrosion-resistant cobalt-free high-entropy alloy and preparation method thereof

Abstract

The invention discloses a Laves phase reinforced hot corrosion resistant cobalt-free high-entropy alloy and a preparation method thereof. The high-entropy alloy is prepared from the following components in percentage by mass: 14.0 to 16.0 percent of Cr, 34.0 to 36.0 percent of Ni, 1.0 to 2.0 percent of Si, 1.5 to 7.0 percent of Mo, 0.01 to 0.02 percent of Nd, 0.005 to 0.015 percent of C and the balance of Fe and inevitable impurities. In the high-entropy alloy, Fe, Ni, Cr and Mo elements jointly form a solid solution matrix, a Laves phase is separated out from the solid solution matrix, and the Laves phase is jointly formed by Mo, Cr, Si, Fe and Ni elements. The structure of the Laves phase in the high-entropy alloy is AB2 type, A is Mo element, and B is Cr, Si, Fe and Ni elements. In the high-entropy alloy, the Laves phase forms dispersively distributed particles in the solid solution matrix. According to the high-entropy alloy and the preparation method thereof disclosed by the invention, the precipitation of a Laves phase is successfully promoted by utilizing the synergistic effect of Si and Mo elements, and the SiO2 passivation layer is formed by adding the Si element, so that the bottleneck that the mechanical property and the thermal corrosion resistance of the traditional high-entropy alloy are difficult to obtain at the same time is broken through.

Description

Technical Field

[0001] The invention relates to a high entropy alloy and a preparation method thereof, in particular to a Laves phase enhanced heat-resistant corrosion-resistant cobalt-free high entropy alloy and a preparation method thereof. Background Art

[0002] With the rapid development of high-tech fields such as aerospace, energy and chemical industry, the demand for high-performance heat-resistant corrosion alloys is becoming increasingly urgent. High-entropy alloys, with their unique composition design and structural characteristics, have shown great potential in exhibiting excellent mechanical properties, heat-resistant corrosion properties and high-temperature performance, and are regarded as ideal materials to meet the needs of these key fields. However, most of the high-entropy alloys currently developed contain expensive cobalt elements, which undoubtedly increases production costs and limits their widespread industrial applications.

[0003] Compared with traditional dilute solid solution alloys, high entropy alloys have shown many significant advantages in performance due to their diversity and adjustability of composition. However, it is worth noting that high entropy alloys with face-centered cubic structure generally face the problem of insufficient strength, while high entropy alloys with body-centered cubic structure, although with high strength, perform poorly in terms of plasticity. This mismatch between strength and plasticity has seriously hindered the widespread application of high entropy alloys in engineering practice. In addition, for high entropy alloys used in high-temperature corrosion environments, their heat corrosion resistance is crucial. Unfortunately, existing studies have shown that high-strength high-entropy alloys often have poor heat corrosion resistance, while high-entropy alloys with excellent heat corrosion resistance often perform poorly in terms of strength and toughness. This trade-off between mechanical properties and heat corrosion resistance further limits the widespread application of high entropy alloys in the engineering field. Summary of the invention

[0004] Purpose of the invention: In order to overcome the deficiencies in the prior art, the present invention provides a Laves phase enhanced heat-resistant and corrosion-resistant cobalt-free high entropy alloy and a preparation method thereof, aiming to develop a cobalt-free high entropy alloy to reduce production costs and simultaneously improve its mechanical properties and heat-resistant corrosion properties.

[0005] Technical solution: To achieve the above-mentioned purpose, the Laves phase enhanced heat-resistant and corrosion-resistant cobalt-free high entropy alloy of the present invention comprises the following components in percentage by mass: Cr: 10.0-20.0%, Ni: 30.0-40.0%, Si: 0.5-3.0%, Mo: 1.0-10.0%, Nd: 0.01-0.02%, C: 0.005-0.015%, and the remaining components are Fe and inevitable impurities; in the high entropy alloy, Fe, Ni, Cr, and Mo elements jointly form a solid solution matrix, and a Laves phase is precipitated in the solid solution matrix, and the Laves phase is jointly formed by Mo, Cr, Si, Fe, and Ni elements.

[0006] Furthermore, the components of the high entropy alloy are composed according to the following mass percentages: Cr: 14.0-16.0%, Ni: 34.0-36.0%, Si: 1.0-2.0%, Mo: 1.5-7.0%, Nd: 0.01-0.02%, C: 0.005-0.015%, and the remaining components are Fe and unavoidable impurities.

[0007] Furthermore, the structure of the Laves phase in the high entropy alloy is AB 2 Type, where A is Mo element and B is Cr, Si, Fe, or Ni element.

[0008] Furthermore, in the high entropy alloy, Si and Cr elements can form SiO on the surface of the high entropy alloy. 2 and Cr 2 O 3 Passivation layer.

[0009] Furthermore, in the high entropy alloy, the Laves phase forms dispersed particles in the solid solution matrix, the size range of the Laves phase particles spans from nanometer scale to micrometer scale, and the size distribution of the Laves phase particles presents a multi-peak characteristic.

[0010] Furthermore, in the high entropy alloy, the Laves phase forms dispersed particles and needles in the solid solution matrix, the Laves phase needles are parallel distributed in a small range, and the Laves phase needles are staggered distributed in a large range.

[0011] Furthermore, a method for preparing a Laves phase enhanced heat-resistant and corrosion-resistant cobalt-free high-entropy alloy comprises the following steps: step a: configuring raw materials according to a set alloy mass percentage, and subjecting all the raw materials after configuration to vacuum induction melting to obtain an alloy melt; step b: casting the obtained alloy melt into a mold, and subjecting the cast alloy ingot to a process treatment to obtain a high-entropy alloy.

[0012] Furthermore, in step a, after batching, all raw materials are mixed and heated to 1500°C to 1600°C at a heating rate of not less than 10°C / min, and melted at this temperature for at least 15 minutes, and a vacuum induction melting process is used to obtain an alloy melt.

[0013] Furthermore, in step b, the alloy ingot obtained by casting is sequentially subjected to hot rolling, cold rolling, annealing and aging treatment processes.

[0014] Furthermore, in step b, the hot rolling temperature is 1200°C to 1280°C, and the deformation amount is 65 to 70%; the cold rolling deformation is carried out at room temperature, and the deformation amount is 75 to 80%; the cold-rolled alloy is annealed at 1150°C for 30 minutes and then cooled to room temperature, and then aged at 700°C for 5 hours to obtain a high entropy alloy.

[0015] Beneficial effects: The Laves phase enhanced heat-resistant and corrosion-resistant cobalt-free high-entropy alloy and the preparation method thereof of the present invention have the following beneficial effects:

[0016] 1) The cobalt-free high entropy alloy design effectively reduces the alloy cost and overcomes the application cost limitation caused by the high cobalt content in traditional high entropy alloys;

[0017] 2) By controlling the element ratio and heat treatment process, a dispersed Laves phase is precipitated in the alloy; the Laves phase precipitates as the second phase, which can effectively enhance the strength of the alloy and improve the creep resistance; in addition, the Laves phase is rich in Cr and Si, which can promote the formation of a passivation film on the alloy surface in a hot corrosion environment, improve the alloy's heat corrosion resistance, and successfully overcome the contradiction between the strength and heat corrosion resistance of traditional high entropy alloys;

[0018] 3) The metallographic structure of the present invention has dispersedly distributed Laves phase needles, which are distributed in parallel in a small range and in staggered distribution in a large range; the needles distributed in parallel in a small range can separate the matrix into micro-regions, inhibiting the large-scale accumulation of dislocations, and the needles distributed in a staggered manner in a large range can force fatigue cracks to change the direction of expansion, consume the energy of the cracks, and thus enhance the strength properties of the alloy; in addition, the needles distributed in parallel in a small range have a barrier effect, which can form a continuous corrosion-resistant barrier in a specific direction to hinder the penetration of the corrosive medium; the needles distributed in a staggered manner in a large range have a maze effect, forcing the corrosive medium to frequently turn when expanding, extending the corrosion path, and thus enhancing the corrosion resistance of the alloy;

[0019] 4) The Laves phase enhanced heat-resistant and corrosion-resistant cobalt-free high entropy alloy prepared by the present invention has excellent mechanical properties and heat-resistant corrosion properties; the room temperature tensile fracture strength is not less than 1020MPa, the elongation is not less than 28%, and the molten mixed salt (NaCl-NaSO 4 , 25-75mol%) after 24h corrosion, weight change ≤2.0mg / cm 2 , meeting the urgent needs of aerospace, energy and chemical industries for high-performance heat-resistant and corrosion-resistant alloys;

[0020] 5) The present invention provides a controllable preparation method, which can effectively control the composition, microstructure and properties of the alloy through process steps such as vacuum induction melting, hot rolling, cold rolling, annealing and aging treatment. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] Attached Figure 1 The thermodynamic calculation phase diagram of the alloy of Example 4;

[0022] Attached Figure 2 The metallographic picture of the alloy microstructure of Example 4;

[0023] Attached Figure 3 This is an enlarged metallographic picture of the alloy microstructure of Example 4. DETAILED DESCRIPTION

[0024] The present invention will be further described below in conjunction with the accompanying drawings.

[0025] As attached Figures 1 to 3 The Laves phase enhanced heat-resistant and corrosion-resistant cobalt-free high-entropy alloy comprises the following components in percentage by mass: Cr: 10.0-20.0%, Ni: 30.0-40.0%, Si: 0.5-3.0%, Mo: 1.0-10.0%, Nd: 0.01-0.02%, C: 0.005-0.015%, and the remaining components are Fe and unavoidable impurities; in the high-entropy alloy, Fe, Ni, Cr, and Mo elements jointly form a solid solution matrix, a Laves phase is precipitated in the solid solution matrix, and the Laves phase is jointly formed by Mo, Cr, Si, Fe, and Ni elements.

[0026] Preferably, the components of the high entropy alloy are composed according to the following mass percentages: Cr: 14.0-16.0%, Ni: 34.0-36.0%, Si: 1.0-2.0%, Mo: 1.5-7.0%, Nd: 0.01-0.02%, C: 0.005-0.015%, and the remaining components are Fe and unavoidable impurities.

[0027] The present invention uses alloy elements such as Cr, Ni, Si, Mo, Nd, C, and Fe to form a Laves phase-enhanced heat-resistant and corrosion-resistant cobalt-free high-entropy alloy through specific composition ratios and microstructure control, achieving excellent mechanical properties and heat-resistant corrosion properties. The specific principles are as follows:

[0028] Mo, Cr, Si, Fe, and Ni elements will form a Laves phase in a specific ratio, and its structure is AB 2Type, wherein A is Mo element, and B is Cr, Si, Fe, Ni element. In the high entropy alloy, the solid solution matrix constitutes the first phase, and the dispersed Laves phase particles play a strengthening role as the second phase. The size distribution of these Laves phase particles shows a multi-peak feature, and the size range spans 20 nanometers to 3 microns. Nanoscale Laves phase particles have high interfacial energy and precipitation density, which can effectively hinder dislocation movement, thereby significantly improving the strength and hardness of the alloy. Micron-scale Laves phase particles have excellent thermal stability, can maintain structural integrity even in high temperature environments, and significantly enhance the creep resistance of the alloy. The synergistic effect of this multi-scale strengthening mechanism ensures that the alloy can exhibit excellent mechanical properties under different working conditions. In addition, the Laves phase is rich in anti-corrosion elements such as Cr and Si, which can promote the formation of a dense oxide film on the surface of the alloy, effectively prevent the erosion of high-temperature corrosive media, and enhance the heat corrosion resistance of the alloy.

[0029] In addition, in the high entropy alloy, the Laves phase forms dispersed particles and needles in the solid solution matrix, and the Laves phase needles are distributed in parallel in a small range and in an interlaced manner in a large range.

[0030] In terms of the strength properties of the alloy, the dense parallel distribution of Laves phase needles in a small range can separate the solid solution matrix into multiple micro-regions, limit the physical space for dislocation proliferation, and make it difficult for dislocations to form long-range slip bands, thereby inhibiting the large-scale accumulation of dislocations and delaying the initiation of fatigue microcracks. The staggered distribution of Laves phase needles in a large range can force fatigue cracks to frequently change their extension direction, consume the energy of the cracks, and thus enhance the toughness of the alloy.

[0031] In terms of heat corrosion resistance, since Laves phases are more corrosion resistant than solid solution matrix, small-scale parallel Laves phase needles have a barrier effect, which can form a continuous corrosion barrier in a specific direction and hinder the penetration of corrosive media. Large-scale staggered Laves phase needles have a maze effect. The staggered needle phases can force the corrosive media to turn frequently when expanding, extend the corrosion path, and reduce the corrosion rate.

[0032] In high entropy alloys, various elements work together. Among them, Cr is the key element to improve the corrosion resistance of the alloy, and has a significant effect on increasing the alloy's resistance to thermal corrosion. When the Cr content reaches a critical value, a high-density Cr layer will form on the alloy surface. 2 O 3The passivation film can protect the metal surface from high temperature oxidation and thermal corrosion caused by O, S, Cl, etc., and protect the alloy from oxidation corrosion. However, the increase in Cr content will inevitably enhance the precipitation tendency of the Cr-rich body-centered α-Cr phase in the alloy. The preferred amount of Cr in the present invention is 14.0-16.0%.

[0033] Fe as a matrix metal can reduce the cost of the alloy and form a solid solution matrix with other elements to improve the comprehensive properties of the alloy. The preferred amount of Fe in the present invention is 39.0-49.0%.

[0034] The Ni element has high chemical stability, can improve the toughness, oxidation resistance and corrosion resistance of the alloy, and can solid-dissolve a variety of alloy elements without forming harmful phases. The preferred amount of Ni used in the present invention is 34.0-36.0%.

[0035] The addition of Si element can promote the formation of SiO on the alloy surface. 2 The formation of the passivation layer hinders the dissolution of metal elements in the molten mixed salt, thus making up for the shortcoming of the corrosion resistance of the cobalt-free alloy. The preferred amount of Si in the present invention is 1.0-2.0%.

[0036] Mo can be used as a solid solution element to strengthen the matrix by solid solution, and can also form a precipitated phase to strengthen the matrix by fine grain and precipitation. At high temperatures, the enrichment of Mo on the alloy surface can hinder the progress of hot corrosion and improve the alloy's resistance to hot corrosion. By accurately controlling the Si / Mo ratio, the precipitation driving force of the Laves phase and the matrix stability are balanced, avoiding the phase separation tendency caused by the absence of cobalt. The preferred amount of Mo used in the present invention is 1.5-7.0%.

[0037] The addition of Nd element can adjust the alloy microstructure and improve the mechanical properties because it has a positive effect on the purification of molten steel and the modification of inclusions. The preferred amount of Nd used in the present invention is 0.01-0.02%.

[0038] The C element is not only an important grain boundary strengthening element, but also can be combined with a certain amount of TCP phase forming elements to exist as an alloy structure stabilizing element. The preferred amount of C used in the present invention is 0.005-0.015%.

[0039] In the present invention, the composition, especially the content of Si and Mo, is precisely controlled, and the synergistic effect of Si and Mo elements is utilized to successfully promote the precipitation of Laves phase, and SiO is formed by adding Si element. 2 The passivation layer achieves the goal of simultaneously improving the mechanical properties and heat corrosion resistance of the high-entropy alloy, and can also enable the high-entropy alloy to maintain good plasticity.

[0040] The present invention also provides a method for preparing a Laves phase enhanced heat-resistant and corrosion-resistant cobalt-free high-entropy alloy, comprising the following steps:

[0041] Step a: adopting a vacuum induction melting process, when the raw materials are batched, the raw materials are batched according to the set alloy mass percentage; then, all the batched raw materials are subjected to vacuum induction melting to obtain an alloy melt;

[0042] Step b: casting the alloy melt prepared in step a, and subjecting the cast alloy ingot to process to obtain a high entropy alloy rod or plate.

[0043] As a further preferred preparation method of the present invention, in step a, after batching, all raw materials are mixed and heated to 1500°C to 1600°C at a heating rate of not less than 10°C / min, and melted at the temperature for at least 15 minutes, and a vacuum induction melting process is used to obtain an alloy melt.

[0044] In addition, in step b, the alloy ingot obtained by casting is sequentially subjected to hot rolling, cold rolling, annealing and aging treatment processes. Specifically, in step b, the hot rolling temperature is 1200°C to 1280°C. In order to avoid deformation and cracking during the hot rolling process, the alloy is repeatedly returned to the furnace and rolled again during the hot deformation process, and the deformation amount is 65-70%; the cold rolling deformation is carried out at room temperature, and the deformation amount is 75-80%; the alloy after cold rolling is annealed at 1150°C for 30 minutes and then cooled to room temperature, and then aged at 700°C for 5 hours, and finally a high entropy alloy bar or plate is obtained.

[0045] Embodiment 1:

[0046] In this embodiment, the Laves phase enhanced heat-resistant and corrosion-resistant cobalt-free high-entropy alloy and the preparation method thereof include the following steps:

[0047] Step a. A vacuum induction melting process is adopted. When the raw materials are batched, the raw material components are prepared according to the following mass percentage composition: Cr: 15.0%, Ni: 35.0%, Si: 1.5%, Mo: 1.5%, Nd: 0.01%, C: 0.01%, and the balance is Fe; then the weighed raw materials are mixed, heated at a heating rate of not less than 10°C / min, and the temperature is increased to 1500°C to 1600°C, and the temperature is kept for at least 15 minutes, and a vacuum induction melting process is adopted to obtain an alloy melt;

[0048] Step b: casting the alloy melt prepared in step a, and subjecting the cast alloy ingot to hot rolling, cold rolling, annealing and aging treatment processes in sequence; wherein the initial hot rolling temperature is 1250°C, and in order to avoid deformation and cracking during the hot rolling process, the alloy is returned to the furnace for many times during the hot deformation process and then rolled again, with a deformation amount of 68%; the cold rolling deformation is carried out at room temperature, with a deformation amount of 76%; the cold-rolled alloy is annealed at 1150°C for 30 minutes and then cooled to room temperature, and then aged at 700°C for 5 hours to obtain Laves phase enhanced heat-resistant and corrosion-resistant cobalt-free high-entropy alloy rods or plates.

[0049] After experimental testing, the test results show that the room temperature tensile fracture strength of the Laves phase enhanced heat-resistant and corrosion-resistant cobalt-free high entropy alloy plate prepared in this embodiment is 1020MPa, the fracture elongation is 37%, and it has good strength and plasticity; in 850℃ molten mixed salt (NaCl-NaSO 4 , 25-75mol%) after 24h corrosion, the weight change is 2.0mg / cm 2 , and its hot corrosion resistance is better than that of traditional Cr-containing ferritic steel (12CrMoV, T91, etc.) or austenitic stainless steel (304, 316L and 317, etc.). Through component design and reasonable heat treatment system, the Laves strengthening phase is successfully precipitated in the Laves phase-enhanced hot corrosion-resistant cobalt-free high entropy alloy matrix prepared in this embodiment. The Laves phase-enhanced hot corrosion-resistant cobalt-free high entropy alloy prepared in this embodiment has excellent mechanical properties, and its hot corrosion resistance is better than that of traditional Cr-containing ferritic steel or austenitic stainless steel. It can be used as parts in the fields of aerospace, energy and chemical industry, and can greatly improve the safety and reliability of facilities and reduce equipment maintenance costs.

[0050] Embodiment 2:

[0051] This embodiment is basically the same as the first embodiment, except that: in this embodiment, the preparation method of the Laves phase enhanced heat-resistant and corrosion-resistant cobalt-free high-entropy alloy comprises the following steps:

[0052] Step a: adopting a vacuum induction melting process, when the raw materials are batched, the raw material components are batched according to the following mass percentage composition: Cr: 15.0%, Ni: 35.0%, Si: 1.5%, Mo: 3.0%, Nd: 0.01%, C: 0.01%, and the balance is Fe; then all the raw materials weighed after the batching are subjected to vacuum induction melting to obtain an alloy melt;

[0053] Step b: This step is the same as that of Example 1.

[0054] After experimental testing, the test results show that the room temperature tensile fracture strength of the Laves phase enhanced heat-resistant and corrosion-resistant cobalt-free high entropy alloy plate prepared in this embodiment is 1070MPa, the elongation at fracture is 34%, and it has good strength and plasticity; in 850℃ molten mixed salt (NaCl-NaSO 4 , 25-75mol%) after 24h corrosion, the weight change is 1.8mg / cm 2 , and its hot corrosion resistance is better than that of traditional Cr-containing ferritic steel (12CrMoV, T91, etc.) or austenitic stainless steel (304, 316L and 317, etc.). Through component design and reasonable heat treatment system, the Laves strengthening phase is successfully precipitated in the Laves phase-enhanced hot corrosion-resistant cobalt-free high entropy alloy matrix prepared in this embodiment. The Laves phase-enhanced hot corrosion-resistant cobalt-free high entropy alloy prepared in this embodiment has excellent mechanical properties, and its hot corrosion resistance is better than that of traditional Cr-containing ferritic steel or austenitic stainless steel. It can be used as parts in the fields of aerospace, energy and chemical industry, and can greatly improve the safety and reliability of facilities and reduce equipment maintenance costs.

[0055] Embodiment three:

[0056] This embodiment is basically the same as the first embodiment, except that: in this embodiment, the preparation method of the Laves phase enhanced heat-resistant and corrosion-resistant cobalt-free high-entropy alloy comprises the following steps:

[0057] Step a: adopting a vacuum induction melting process, when the raw materials are batched, the raw materials are batched according to the following mass percentage composition: Cr: 15.0%, Ni: 35.0%, Si: 1.5%, Mo: 5.0%, Nd: 0.01%, C: 0.01%, and the balance is Fe; then all the raw materials weighed after batching are subjected to vacuum induction melting to obtain an alloy melt;

[0058] Step b: This step is the same as that of Example 1.

[0059] After experimental testing, the test results show that the room temperature tensile fracture strength of the Laves phase enhanced heat-resistant and corrosion-resistant cobalt-free high entropy alloy plate prepared in this embodiment is 1160MPa, the fracture elongation is 30%, and it has good strength and plasticity; in the 850℃ molten mixed salt (NaCl-NaSO 4 , 25-75mol%) after 24h corrosion, the weight change is 1.3mg / cm 2, and its hot corrosion resistance is better than that of traditional Cr-containing ferritic steel (12CrMoV, T91, etc.) or austenitic stainless steel (304, 316L and 317, etc.). Through component design and reasonable heat treatment system, the Laves strengthening phase is successfully precipitated in the Laves phase-enhanced hot corrosion-resistant cobalt-free high entropy alloy matrix prepared in this embodiment. The Laves phase-enhanced hot corrosion-resistant cobalt-free high entropy alloy prepared in this embodiment has excellent mechanical properties, and its hot corrosion resistance is better than that of traditional Cr-containing ferritic steel or austenitic stainless steel. It can be used as parts in the fields of aerospace, energy and chemical industry, and can greatly improve the safety and reliability of facilities and reduce equipment maintenance costs.

[0060] Embodiment 4:

[0061] This embodiment is basically the same as the first embodiment, except that: in this embodiment, the preparation method of the Laves phase enhanced heat-resistant and corrosion-resistant cobalt-free high-entropy alloy comprises the following steps:

[0062] Step a: adopting a vacuum induction melting process, when the raw materials are batched, the raw material components are batched according to the following mass percentage composition: Cr: 15.0%, Ni: 35.0%, Si: 1.5%, Mo: 7.0%, Nd: 0.01%, C: 0.01%, and the balance is Fe; then all the raw materials weighed after the batching are subjected to vacuum induction melting to obtain an alloy melt;

[0063] Step b: This step is the same as that of Example 1.

[0064] After experimental testing, the test results show that the room temperature tensile fracture strength of the Laves phase enhanced heat-resistant and corrosion-resistant cobalt-free high entropy alloy plate prepared in this embodiment is 1230MPa, the elongation at fracture is 28%, and it has good strength and plasticity; in 850℃ molten mixed salt (NaCl-NaSO 4 , 25-75mol%) after 24h corrosion, the weight change is 0.8mg / cm 2 , and its hot corrosion resistance is better than that of traditional Cr-containing ferritic steel (12CrMoV, T91, etc.) or austenitic stainless steel (304, 316L and 317, etc.). Figure 1 and Figure 2It can be seen that through component design and reasonable heat treatment system, the Laves phase-enhanced heat-resistant and corrosion-resistant cobalt-free high-entropy alloy matrix prepared in this embodiment successfully precipitates the Laves strengthening phase. Compared with Example 1, the proportion of the Laves phase is significantly improved, and the strengthening effect is more obvious. The Laves phase-enhanced heat-resistant and corrosion-resistant cobalt-free high-entropy alloy prepared in this embodiment has excellent mechanical properties, and its heat corrosion resistance is better than that of traditional Cr-containing ferritic steel or austenitic stainless steel. It can be used as parts in the fields of aerospace, energy and chemical industry, and can greatly improve the safety and reliability of facilities and reduce equipment maintenance costs.

[0065] The above is only a preferred embodiment of the present invention. It should be pointed out that for ordinary technicians in this technical field, several improvements and modifications can be made without departing from the principle of the present invention. These improvements and modifications should also be regarded as the scope of protection of the present invention.

Claims

1. Laves phase enhanced heat-resistant and corrosion-resistant cobalt-free high entropy alloy, characterized by: The composition of the high entropy alloy is as follows: Composition: Cr: 10.0-20.0%, Ni: 30.0-40.0%, Si: 0.5-3.0%, Mo: 1.0-10.0%, Nd: 0.01-0.02%, C: 0.005-0.015%, and the remaining components are Fe and inevitable impurities; in the high entropy alloy, Fe, Ni, Cr, and Mo elements jointly form a solid solution matrix, and a Laves phase is precipitated in the solid solution matrix, and the Laves phase is jointly formed by Mo, Cr, Si, Fe, and Ni elements.

2. The Laves phase enhanced heat-resistant and corrosion-resistant cobalt-free high entropy alloy according to claim 1, characterized in that: The components of the high entropy alloy are composed according to the following mass percentages: Cr: 14.0-16.0%, Ni: 34.0-36.0%, Si: 1.0-2.0%, Mo: 1.5-7.0%, Nd: 0.01-0.02%, C: 0.005-0.015%, and the remaining components are Fe and inevitable impurities.

3. The Laves phase enhanced heat-resistant and corrosion-resistant cobalt-free high entropy alloy according to claim 1, characterized in that: The structure of the Laves phase in the high entropy alloy is AB2 type, wherein A is the Mo element, and B is the Cr, Si, Fe, and Ni elements.

4. The Laves phase enhanced heat-resistant and corrosion-resistant cobalt-free high entropy alloy according to claim 3, characterized in that: In the high entropy alloy, Si and Cr elements can form SiO2 and Cr2O3 passivation layers on the surface of the high entropy alloy.

5. The Laves phase enhanced heat-resistant and corrosion-resistant cobalt-free high entropy alloy according to claim 3, characterized in that: In the high entropy alloy, the Laves phase forms dispersed particles in the solid solution matrix, the size range of the Laves phase particles spans from nanometer scale to micrometer scale, and the size distribution of the Laves phase particles presents multi-peak characteristics.

6. The Laves phase enhanced heat-resistant and corrosion-resistant cobalt-free high entropy alloy according to claim 5, characterized in that: In the high entropy alloy, the Laves phase forms dispersed particles and needles in the solid solution matrix. The Laves phase needles are distributed in parallel in a small range, and are distributed in an alternating manner in a large range.

7. The method for preparing the Laves phase enhanced heat-resistant and corrosion-resistant cobalt-free high entropy alloy according to any one of claims 1 to 6, characterized in that: The steps include: Step a: preparing raw materials according to a set alloy mass percentage, and performing vacuum induction melting on all the prepared raw materials to obtain an alloy melt; Step b: casting the obtained alloy melt into a shape, and subjecting the cast alloy ingot to process to obtain a high entropy alloy.

8. The method for preparing the Laves phase enhanced heat-resistant and corrosion-resistant cobalt-free high entropy alloy according to claim 7, characterized in that: In step a, after batching, all raw materials are mixed and heated to 1500°C to 1600°C at a heating rate of not less than 10°C / min, and melted at this temperature for at least 15 minutes, and a vacuum induction melting process is used to obtain an alloy melt.

9. The method for preparing the Laves phase enhanced heat-resistant and corrosion-resistant cobalt-free high entropy alloy according to claim 7, characterized in that: In step b, the alloy ingot obtained by casting is sequentially subjected to hot rolling, cold rolling, annealing and aging treatment processes.

10. The method for preparing the Laves phase enhanced heat-resistant and corrosion-resistant cobalt-free high entropy alloy according to claim 9, characterized in that: In step b, the hot rolling temperature is 1200°C to 1280°C, and the deformation amount is 65% to 70%; the cold rolling deformation is The cold rolled alloy is annealed at 1150℃ for 30min and then cooled to room temperature. After that, the high entropy alloy was obtained by aging treatment at 700℃ for 5h.

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