A multi-principal element alloy with multi-level heterogeneous structure, high strength and toughness, and anti-cavitation-corrosion, and a preparation method and application thereof

Abstract

The application discloses a high-strength and high-toughness multi-principal element alloy with a multi-stage heterogeneous structure and resistance to cavitation-corrosion, and a preparation method and application thereof.The chemical composition of the multi-principal element alloy comprises Fe 27% to 32%, Ni 33% to 37%, Cr 17% to 22%, Al 12% to 15%, Co 1% to 4%, Ti 1% to 4%, and Mo 1% to 4% in terms of atomic percentage (at.%).The multi-principal element alloy comprises a multi-phase structure in which a face-centered cubic phase (FCC) and a body-centered cubic phase (BCC) coexist.Due to the FCC phase and the BCC phase in multiple forms and the precipitated phases in multiple forms in the two phases, a complex multi-stage heterogeneous structure is finally formed, and the strength and plasticity of the alloy are greatly improved.Meanwhile, the alloy has good resistance to cavitation-corrosion, low raw material cost, simple and efficient preparation process and the like, and has a wide application prospect.

Description

Technical Field

[0001] This invention belongs to the field of high-performance alloy materials technology, specifically relating to a high-strength, high-toughness, cavitation-corrosion resistant multi-principal-element alloy with a multi-level heterostructure, its preparation method and application. Background Technology

[0002] Heterogeneous structures (HS) are special structures composed of heterogeneous regions with significantly different mechanical or physical properties. The interaction and coupling between these heterogeneous regions produce synergistic effects, where the combined properties exceed the predictions of the mixing rule. HS materials possess superior mechanical or physical properties that are unattainable by traditional homogeneous materials (Reference 1: P. Sathiyamoorthi, HSKim, Prog. Mater. Sci. 123 (2022) 100709.). Heterogeneous structures have been used to improve the mechanical properties of a range of traditional metallic materials, including titanium alloys, nickel-based superalloys, tungsten alloys, and high-manganese steel. Multilevel heterostructures are heterostructures in which the size and morphology of the matrix and precipitates have different characteristics at multiple scales, and the interaction or coupling between different regions can further improve the material properties (Reference 2: Y. Zhu, X. Wu, Prog. Mater. Sci. 131 (2023) 101019.). For traditional alloys, heterogeneous structures require complex and energy-intensive processes to achieve, such as rolling and heat treatment, and laser additive manufacturing. Obtaining multi-level heterogeneous structures is even more challenging, and such microstructures are almost impossible to achieve using traditional, simple, and low-cost processes (such as casting). In recent years, multi-principal element alloys (also known as high-entropy alloys) have become ideal candidate materials for many harsh environments due to their unique thermodynamic properties and excellent performance. Heterogeneous multi-principal element alloys also typically exhibit superior performance, but they still require costly or lengthy processes for preparation, such as laser additive manufacturing. Furthermore, most of the high-performance multi-principal element alloys developed contain precious elements.

[0003] Cavitation erosion severely impacts critical flow-through and load-bearing components of fluid machinery, such as turbines, pumps, impellers, control valves, and piping. Increased downtime and maintenance significantly compromise the sustainability of these systems, leading to substantial cost increases. Cavitation erosion (CPE) is a complex phenomenon caused by pressure fluctuations within the flow field, resulting in bubble formation and implosion. Imploding bubbles generate high-speed microjet streams and shock waves, damaging adjacent solid surfaces. Repeated impacts from these microjet streams and high-frequency shock waves cause fatigue damage to materials. The presence of corrosive media further exacerbates the destructive process due to the synergistic effect of CPE (mechanical action) and corrosion (electrochemical action). Repeated implosion of vapor bubbles destroys the protective passivation film, accelerating the corrosion process. Stainless steel and copper alloys are commonly used metals in fluid machinery; however, their strength, toughness, and corrosion resistance cannot be improved simultaneously, creating a bottleneck in enhancing their resistance to cavitation-corrosion. Therefore, the development of novel cavitation-corrosion resistant materials is necessary to meet the critical needs of next-generation flow-through components. Existing literature shows that some multi-principal alloys have excellent resistance to cavitation erosion and corrosion (DGLi, DR Chen, P. Liang, Ultrason Sonochem. 35 (2017) 375-381). This invention, through composition design and control, and by using simple casting technology, prepares multi-level heterogeneous multi-principal alloys with high strength and toughness and resistance to cavitation erosion and corrosion. Moreover, this type of alloy has the advantage of lower cost than other multi-principal alloys, and therefore has great application prospects. Summary of the Invention

[0004] To address the shortcomings of existing technologies, the present invention aims to provide a high-strength, high-toughness, and cavitation-corrosion-resistant multi-principal element alloy with a multi-level heterogeneous structure, along with its preparation method and applications. This invention employs a low-alloying strategy, adding low amounts of alloying elements to the matrix alloy to control its microstructure and properties. This solves the technical problems of complex and costly processes for obtaining multi-level heterogeneous structures, as well as the poor cavitation-corrosion resistance and low material strength of key flow-through components in marine equipment, thereby meeting the urgent need for advanced high-strength metallic materials and a new generation of excellent cavitation-corrosion-resistant materials.

[0005] Another objective of this invention is to prepare a multi-principal-element alloy with coexisting FCC and BCC phases and multi-level heterogeneous structure characteristics by means of a direct casting process.

[0006] Another object of the present invention is to use high-strength, high-toughness, and cavitation-corrosion resistant multi-principal-element alloys with multi-level heterostructures to prepare cavitation-corrosion resistant and / or corrosion resistant components.

[0007] The objective of this invention is achieved through the following technical solution:

[0008] A high-strength, high-toughness, cavitation-corrosion resistant Al-Cr-Fe-Ni-Co-Ti-Mo multi-principal-element alloy with a multi-level heterogeneous structure comprises the following components by atomic percentage (at.%): Fe 27%–32%, Ni 33%–37%, Cr 17%–22%, Al 12%–15%, Co 1%–4%, Ti 1%–4%, and Mo 1%–4%; the sum of the atomic percentages of each component is 100%.

[0009] Preferably, the high-strength, high-toughness, and cavitation-corrosion resistant multi-principal-element alloy with a multi-level heterogeneous structure is composed of the following components by atomic percentage: Fe 27%–32%, Ni 33%–37%, Cr 17%–22%, Al 12%–15%, Co 1%–4%, Ti 1%–4%, and Mo 1%–4%.

[0010] Preferably, the high-strength, high-toughness, and cavitation-corrosion resistant multi-principal-element alloy with a multi-level heterogeneous structure comprises the following components by atomic percentage: Fe 27%–28%, Ni 33%–35%, Cr 17%–18.25%, Al 13%–14%, Co 2%–4%, Ti 1%–4%, and Mo 1%–4%.

[0011] Preferably, the multi-principal-element alloy has excellent resistance to cavitation-corrosion, and the cumulative mass loss after 10 hours of cavitation-corrosion in a 3.5 wt.% NaCl solution is no more than 2.6 mg.

[0012] Preferably, the multi-principal element alloy has excellent tensile properties, with a tensile yield strength of not less than 1000 MPa, an ultimate tensile strength of not less than 1400 MPa, and an elongation after fracture of not less than 12% at room temperature.

[0013] More preferably, the multi-principal element alloy has a tensile yield strength of 1000-1150 MPa at room temperature, an ultimate tensile strength of 1400-1650 MPa, and an elongation after fracture of 12-16%.

[0014] Preferably, the microstructure of the multi-principal alloy comprises a face-centered cubic (FCC) phase and a body-centered cubic (BCC) phase.

[0015] More preferably, the morphology of the face-centered cubic (FCC) phase includes ultrafine lamellar, ultrafine rhomboid, and ultrafine worm-like microstructures; the face-centered cubic (FCC) phase contains BCC precipitates;

[0016] More preferably, the body-centered cubic BCC phase (disordered phase) contains BCC precipitates (ordered phase) with spherical, short rod-shaped, and labyrinthine morphologies formed by amplitude modulation decomposition.

[0017] Further preferred, the FCC phase and BCC phase have multiple morphologies and multiple precipitated phases in both phases, ultimately forming a complex multi-level heterostructure.

[0018] Further preferred formulations show that the FCC phase is rich in Fe-Ni elements, the BCC phase is rich in Al elements, and the remaining elements are evenly distributed.

[0019] The aforementioned Al-Cr-Fe-Ni-Co-Ti-Mo multi-principal-element alloy with a multi-level heterogeneous structure, exhibiting high strength, toughness, and resistance to cavitation-corrosion, was prepared by casting.

[0020] Preferably, the preparation method is vacuum arc melting, comprising the following steps:

[0021] (1) Prepare raw materials according to the atomic percentages of each element in the Al-Cr-Fe-Ni-Co-Ti-Mo multi-principal alloy;

[0022] (2) The raw materials prepared in step (1) are subjected to vacuum arc melting, and after cooling, the vacuum arc melting is repeated. The ingot is turned over before each melting. The vacuum arc melting is performed 4 to 7 times in total.

[0023] (3) Melt the ingot from step (2), pour the alloy liquid into a water-cooled copper mold, and after cooling, obtain the high-strength, high-toughness, and cavitation-corrosion resistant multi-principal alloy with a multi-level heterostructure.

[0024] Preferably, the raw material in step (1) comprises pure metals of Al, Cr, Fe, Ni, Co, Ti and Mo or intermediate alloys of Al, Cr, Fe, Ni, Co, Ti and Mo; the purity of the pure metals of Al, Cr, Fe, Ni, Co, Ti and Mo or the intermediate alloys of Al, Cr, Fe, Ni, Co, Ti and Mo is above 99.9 wt.%.

[0025] Preferably, the vacuum arc melting parameters in step (2) are: arc current of 280-340A (temperature of 1500-1700℃) and vacuum degree of 0.05-0.07MPa.

[0026] Preferably, the time for each vacuum arc melting in step (2) is about 4 to 6 minutes.

[0027] Preferably, in step (2), electromagnetic stirring is turned on for 3 to 5 minutes for each vacuum arc melting.

[0028] Preferably, the cooling rate of the water-cooled copper mold in step (3) is 100-500 K / s.

[0029] The above-mentioned high-strength, high-toughness, and cavitation-corrosion resistant multi-principal-element alloys with multi-level heterostructures are used in the preparation of cavitation-erosion and / or corrosion resistant components.

[0030] Compared with the prior art, the present invention has the following advantages:

[0031] (1) This invention uses only a simple and efficient vacuum arc melting casting process to obtain multiphase alloys with multi-level heterogeneous structures. Compared with processes that obtain similar or identical structures through thermomechanical treatment (rolling + annealing), it can significantly reduce energy consumption.

[0032] (2) The multi-level heterogeneous structure of the alloy of the present invention enables the alloy to produce strong non-uniform deformation strengthening (heterogeneous deformation-induced hardening) and other strengthening effects (solid solution strengthening, precipitation strengthening, etc.) during the deformation process, which is significantly stronger than other single-phase alloys or alloys of the same system.

[0033] (3) The alloy of the present invention has high as-cast strength and good plasticity, and at the same time has good resistance to cavitation and corrosion, which meets the performance indicators of advanced structural materials in extreme environments.

[0034] (4) The raw material cost of the alloy of the present invention is low, which is significantly lower than the manufacturing cost of existing multi-principal element alloy systems and even some high-strength steels. Attached Figure Description

[0035] Figure 1 The XRD patterns are of the multi-principal element alloys prepared in Examples 1-3 of this invention.

[0036] Figure 2 The images are scanning electron microscope (SEM) images of the multi-principal-element alloys prepared in Examples 1-3 of this invention.

[0037] Figure 3 The room temperature tensile stress-strain curves of the multi-principal element alloys prepared in Examples 1-3 of this invention.

[0038] Figure 4 The XRD patterns are of the multi-principal element alloys prepared in Comparative Examples 1-4 of this invention.

[0039] Figure 5 The XRD patterns are of the multi-principal element alloys prepared in Comparative Examples 5-7 of this invention.

[0040] Figure 6 These are scanning electron microscope (SEM) images of the multi-principal element alloys prepared in Comparative Examples 1-4 of this invention.

[0041] Figure 7 These are scanning electron microscope (SEM) images of the multi-principal element alloys prepared in Comparative Examples 5-7 of this invention.

[0042] Figure 8The room temperature tensile stress-strain curves are for the multi-principal element alloys prepared in Comparative Examples 1-4 and Example 1 of this invention.

[0043] Figure 9 The room temperature tensile stress-strain curves of the multi-principal element alloys prepared in Comparative Examples 5-7 and Example 1 of this invention are shown.

[0044] Figure 10 Line graphs showing the cumulative mass loss due to cavitation and corrosion in 3.5 wt.% NaCl solution for the multi-principal element alloys prepared in Examples 1-3 and Comparative Examples 1-7 of this invention. Detailed Implementation

[0045] The following examples further illustrate the specific implementation of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, and the implementation and protection of the present invention are not limited thereto.

[0046] Cavitation-corrosion resistance: Cavitation-corrosion tests were conducted on an ultrasonic vibration cavitation tester in accordance with the GB / T 6383-2009 standard.

[0047] Example 1:

[0048] This embodiment describes the preparation of high-strength, tough, and cavitation-corrosion-resistant Fe with a multi-level heterogeneous structure using a vacuum arc melting casting process. 27 Ni 35 Cr 18.25 Al 13.75 A Co2Ti2Mo2 multi-principal element alloy, the chemical composition of which, by atomic percentage, is: Fe 27%, Ni 35%, Cr 18.25%, Al 13.75%, Co 2%, Ti 2%, Mo 2%. The smelting process specifically includes the following steps:

[0049] (1) Select seven pure metal blocks (particles) or intermediate metal blocks (particles) with a purity of 99.9 wt.% or higher: Fe, Ni, Cr, Al, Co, Ti and Mo. Before batching, clean the oxide film and impurities on the surface of the raw materials. When batching, convert the atomic ratio into the percentage of each element's mass to the total mass and weigh them.

[0050] (2) Place the prepared metal blocks (granules) into a copper crucible in the melting furnace, and place Ti granules into other crucibles. Then, close the furnace door, begin evacuating (0.002 Pa), and then backfill with an argon atmosphere (0.05 MPa). First, begin melting the Ti granules to absorb the residual O element in the furnace cavity, and then begin melting the multi-principal alloy. First, increase the arc current to 200 A to melt the granules, then increase the current to 320 A for 1 minute of melting, and then turn on the electromagnetic stirring for 3 minutes of melting. After melting, reduce the current to 60 A and then extinguish the arc. The alloy is cooled to room temperature along with the crucible.

[0051] (3) Use a robotic arm to flip the ingot, and then repeatedly heat and melt the ingot.

[0052] (4) After repeating the melting process six times, the ingot is moved to the suction casting station, and the mechanical pump is turned on simultaneously. Melting then begins, and once the ingot has turned into molten metal, the suction casting button is pressed, and the molten alloy falls into a water-cooled copper mold. After cooling to room temperature, a sample is taken to obtain Fe. 27 Ni 35 Cr 18.25 Al 13.75 Co2Ti2Mo2 main alloy ingot.

[0053] Figure 1 , Figure 2 Fe 27 Ni 35 Cr 18.25 Al 13.75 XRD pattern and scanning electron microscope (SEM) image of the Co2Ti2Mo2 multi-principal element alloy. It can be seen that the Fe prepared in this example... 27 Ni 35 Cr 18.25 Al 13.75 The Co2Ti2Mo2 multi-principal-element alloy exhibits a structure of face-centered cubic (FCC) and body-centered cubic (BCC) phases. XRD patterns reveal characteristic diffraction peaks of the ordered BCC phase (B2) near 31°. Scanning electron microscopy (SEM) images show that the grains are clearly separated by a thin FCC film. The FCC phase exhibits different morphologies within different grains, including rhomboid blocky FCC phases, worm-like strip-like FCC phases, and lamellar FCC phases. Under casting conditions, the width of the FCC phase is very small. Rhomboid FCC phases are arranged in a specific orientation within the BCC grains, forming distinct banded regions. Furthermore, the BCC phase between these strip-like regions exhibits different decomposition phase morphologies, including spherical precipitates and labyrinthine structures resulting from amplitude modulation decomposition. This observation is consistent with the XRD results, confirming that the BCC phase underwent an ordered phase transformation process during cooling.

[0054] Figure 3 For Fe27 Ni 35 Cr 18.25 Al 13.75 The room temperature tensile stress-strain curves of the Co2Ti2Mo2 multi-principal-element alloy are shown. It can be seen that this alloy with a multi-level heterogeneous structure exhibits significant strengthening behavior, with a yield strength (YS) of approximately 1056 MPa, a tensile strength (UTS) of approximately 1526 MPa, and a total elongation (E1) of approximately 15.6% (Table 1). This indicates that the alloy achieves a perfect balance between strength and plasticity in the as-cast state.

[0055] The results of the cavitation-corrosion experiment are as follows: Figure 10 As shown in Table 2, the high-entropy alloy lost 2.4 mg of mass after 10 h of cavitation-corrosion in a 3.5 wt.% NaCl solution. Under the same conditions, the tested nickel-aluminum bronze alloy (CuAl10Fe5Ni5, wt.%) lost 5.7 mg of mass after 10 h, indicating that the prepared multi-principal element alloy has superior resistance to cavitation-corrosion.

[0056] Example 2:

[0057] This embodiment describes the preparation of high-strength, tough, and cavitation-corrosion-resistant Fe with a multi-level heterogeneous structure using a vacuum arc melting casting process. 28 Ni 34 Cr 17 Al 13 The Co3Ti4Mo1 multi-principal element alloy has the following chemical composition (atomic percentage): Fe 28%, Ni 34%, Cr 17%, Al 13%, Co 3%, Ti 4%, Mo 1%. The smelting process specifically includes the following steps:

[0058] (1) Select seven pure metal blocks (particles) or intermediate metal blocks (particles) with a purity of 99.9 wt.% or higher: Fe, Ni, Cr, Al, Co, Ti and Mo. Before batching, clean the oxide film and impurities on the surface of the raw materials. When batching, convert the atomic ratio into the percentage of each element's mass to the total mass and weigh them.

[0059] (2) Place the prepared metal blocks (granules) into a copper crucible in the melting furnace, and place Ti granules in another crucible. Then, close the furnace door, begin evacuating (0.001 Pa), and then backfill with an argon atmosphere (0.06 MPa). First, begin melting the Ti granules to absorb the residual O element in the furnace cavity, and then begin melting the multi-principal alloy. First, increase the arc current to 195 A to melt the granules, then increase the current to 330 A for 50 seconds of melting. Then, turn on the electromagnetic stirring and melt for 3.5 minutes. After melting, reduce the current to 65 A and extinguish the arc. The alloy is cooled to room temperature along with the crucible.

[0060] (3) Use a robotic arm to flip the ingot, and then repeatedly heat and melt the ingot.

[0061] (4) After repeating the melting process five times, the ingot is moved to the suction casting station, and the mechanical pump is turned on simultaneously. Melting then begins. Once the ingot has turned into molten metal, the suction casting button is pressed, and the molten alloy falls into a water-cooled copper mold. After cooling to room temperature, a sample is taken to obtain Fe. 28 Ni 34 Cr 17 Al 13 Co3Ti4Mo1 main alloy ingot.

[0062] Figure 1 , Figure 2 Fe 28 Ni 34 Cr 17 Al 13 XRD pattern and scanning electron microscope (SEM) image of the Co3Ti4Mo1 multi-principal element alloy. It can be seen that the Fe prepared in this example... 28 Ni 34 Cr 17 Al 13 The Co3Ti4Mo1 multi-principal alloy exhibits a face-centered cubic (FCC) and body-centered cubic (BCC) phase structure. XRD patterns reveal characteristic diffraction peaks of the ordered BCC phase (B2) near 31°. Scanning electron microscopy (SEM) images show that the grains are clearly separated by a thin FCC film. The FCC phase exhibits different morphologies within different grains. Similarly, the BCC phase displays various decomposition or precipitate morphologies, including spherical precipitates and labyrinthine structures resulting from amplitude modulation decomposition.

[0063] Figure 3 For Fe 28 Ni 34 Cr 17 Al 13 The room temperature tensile stress-strain curves of the Co3Ti4Mo1 multi-principal-element alloy are shown. It can be seen that this alloy with a multi-level heterogeneous structure exhibits significant strengthening behavior, with a yield strength (YS) of approximately 1090 MPa, a tensile strength (UTS) of approximately 1552 MPa, and a total elongation (E1) of approximately 12.3% (Table 1). This indicates that the alloy achieves a perfect balance between strength and plasticity in the as-cast state.

[0064] The results of the cavitation-corrosion experiment are as follows: Figure 10 As shown in Table 2, Fe 28 Ni 34 Cr 17 Al 13The Co3Ti4Mo1 multi-principal alloy lost 2.6 mg of mass after cavitation-corrosion in a 3.5 wt.% NaCl solution for 10 h. Under the same conditions, the nickel-aluminum bronze alloy lost 5.7 mg of mass after 10 h, indicating that the prepared multi-principal alloy has superior resistance to cavitation-corrosion.

[0065] Example 3:

[0066] This embodiment describes the preparation of high-strength, tough, and cavitation-corrosion-resistant Fe with a multi-level heterogeneous structure using a vacuum arc melting casting process. 27 Ni 33 Cr 17 Al 14 The Co4Ti1Mo4 multi-principal element alloy has the following chemical composition (atomic percentage): Fe 27%, Ni 33%, Cr 17%, Al 14%, Co 4%, Ti 1%, Mo 4%. The smelting process specifically includes the following steps:

[0067] (1) Select seven pure metal blocks (particles) or intermediate metal blocks (particles) with a purity of 99.9 wt.% or higher: Fe, Ni, Cr, Al, Co, Ti and Mo. Before batching, clean the oxide film and impurities on the surface of the raw materials. When batching, convert the atomic ratio into the percentage of each element's mass to the total mass and weigh them.

[0068] (2) Place the prepared metal blocks (granules) into a copper crucible in the melting furnace, and place Ti granules into other crucibles. Then, close the furnace door, begin evacuating (0.002 Pa), and then backfill with an argon atmosphere (0.07 MPa). First, begin melting the Ti granules to absorb the residual O element in the furnace cavity, and then begin melting the multi-principal alloy. First, increase the arc current to 220 A to melt the granules, then increase the current to 340 A for 1.5 minutes of melting. Then, turn on the electromagnetic stirring and melt for 4.5 minutes. After melting, reduce the current to 60 A and extinguish the arc. The alloy is cooled to room temperature along with the crucible.

[0069] (3) Use a robotic arm to flip the ingot, and then repeatedly heat and melt the ingot.

[0070] (4) After repeating the melting process six times, the ingot is moved to the suction casting station, and the mechanical pump is turned on simultaneously. Melting then begins, and once the ingot has turned into molten metal, the suction casting button is pressed, and the molten alloy falls into a water-cooled copper mold. After cooling to room temperature, a sample is taken to obtain Fe. 27 Ni 33 Cr 17 Al 14 Co4Ti1Mo4 main alloy ingot.

[0071] Figure 1 , Figure 2 Fe 27 Ni 33 Cr 17 Al 14 XRD pattern and scanning electron microscope (SEM) image of the Co4Ti1Mo4 multi-principal element alloy. It can be seen that the Fe prepared in this example... 27 Ni 33 Cr 17 Al 14 Co4Ti1Mo4 multi-principal-element alloys exhibit face-centered cubic (FCC) and body-centered cubic (BCC) phase structures. XRD patterns reveal characteristic diffraction peaks of the ordered BCC phase (B2) near 31°. Scanning electron microscopy (SEM) images show that the grains are clearly separated by a thin FCC film. The FCC phase exhibits different morphologies within different grains. Similarly, the BCC phase displays various decomposition or precipitate morphologies, including spherical precipitates and labyrinthine structures resulting from amplitude modulation decomposition.

[0072] Figure 3 For Fe 27 Ni 33 Cr 17 Al 14 The room temperature tensile stress-strain curves of the Co4Ti1Mo4 multi-principal-element alloy are shown. It can be seen that this alloy with a multi-level heterogeneous structure exhibits significant strengthening behavior, with a yield strength (YS) of approximately 1133 MPa, an ultimate tensile strength (UTS) of approximately 1619 MPa, and a total elongation (E1) of approximately 12.7% (Table 1). This indicates that the alloy achieves a good balance between strength and plasticity in the as-cast state.

[0073] The results of the cavitation-corrosion experiment are as follows: Figure 10 As shown in Table 2, Fe 27 Ni 33 Cr 17 Al 14 The Co4Ti1Mo4 multi-principal alloy lost 2.5 mg of mass after cavitation-corrosion in a 3.5 wt.% NaCl solution for 10 h. Under the same conditions, the tested nickel-aluminum bronze alloy lost 5.7 mg of mass after 10 h, indicating that the prepared multi-principal alloy has superior resistance to cavitation-corrosion.

[0074] Comparative Example 1

[0075] The comparative example describes the preparation of Fe without a multi-level heterostructure using a vacuum arc melting casting process. 30 Ni 35 Cr 21 Al 14A multi-principal element alloy was prepared. The chemical composition of this alloy, in atomic percentage, is: Fe 30%, Ni 35%, Cr 21%, and Al 14%. It should be noted that this alloy can be understood as an alloy with zero Co, Ti, and Mo content, i.e., a matrix alloy. The alloy preparation process is the same as in Example 1, and is simplified here: Before batching, the oxide film and impurities on the surface of the raw materials are cleaned. During batching, the atomic ratio is converted into the percentage of each element's mass to the total mass for weighing. The prepared metal raw materials are placed in a crucible, the furnace door is closed, and a vacuum is initially drawn, followed by argon refilling. Once the required atmosphere is reached, arc melting begins. The melting current is 320A, and the melting is repeated 6 times. Then, the mixture is suction-cast and removed after complete cooling to obtain Fe. 30 Ni 35 Cr 21 Al 14 Multi-principal element alloys.

[0076] Fe in this comparative example 30 Ni 35 Cr 21 Al 14 Observation of phase types and microstructure of multi-principal element alloys. Figure 4 It can be seen that the alloy exhibits a typical two-phase structure: BCC(B2)+FCC. Figure 6 In the sample, the darker areas represent the BCC phase, and the lighter areas represent the FCC phase. These two phases are intermixed, but the sample does not exhibit the multi-level heterogeneous structure found in similar embodiments. Room temperature tensile results are shown below. Figure 8 As shown, its yield strength is 571 MPa, tensile strength is 1112 MPa, and elongation after fracture is 20.5% (Table 1). Using an ultrasonic vibration cavitation erosion testing machine, the alloy showed a mass reduction of 5.8 mg after cavitation-corrosion in a 3.5 wt.% NaCl solution for 10 hours, significantly greater than all other examples (see Table 2). A comprehensive comparison of the microstructure and properties between this comparative example and the examples demonstrates that the simultaneous addition of Co, Ti, and Mo has a significant regulatory effect on the microstructure of the alloy, and simultaneously improves its mechanical properties and cavitation-corrosion resistance.

[0077] Comparative Example 2

[0078] The comparative example describes the preparation of Fe without a multi-level heterostructure using a vacuum arc melting casting process. 28 Ni 34 Cr 20 Al 14The Co4 multi-principal element alloy has the following chemical composition (atomic percentage): Fe 28%, Ni 34%, Cr 20%, Al 14%, and Co 4%. It should be noted that this alloy can be understood as having zero Ti and zero Mo content. The alloy preparation process is the same as in Example 1, but simplified here: Before batching, the oxide film and impurities on the surface of the raw materials are cleaned. During batching, the atomic ratio is converted into the percentage of each element's mass to the total mass for weighing. The prepared metal raw materials are placed in a crucible, the furnace door is closed, and a vacuum is initially drawn, followed by argon refilling. Once the required atmosphere is reached, arc melting begins. The melting current is 320A, and the melting is repeated 6 times. Then, the mixture is suction-cast and removed after complete cooling to obtain Fe. 28 Ni 34 Cr 20 Al 14 Co4 multi-principal element alloy.

[0079] Fe in this comparative example 28 Ni 34 Cr 20 Al 14 Phase types and microstructure of Co4 multi-principal alloy were observed. Figure 4 It can be seen that the alloy exhibits a typical two-phase structure: BCC(B2)+FCC. Figure 6 In the sample, the darker areas represent the BCC phase, and the lighter areas represent the FCC phase. These two phases are intermixed, but the sample does not exhibit the multi-level heterogeneous structure found in similar embodiments. Room temperature tensile results are shown below. Figure 8 As shown, its yield strength is 479 MPa, tensile strength is 1050 MPa, and elongation after fracture is 28.1% (Table 1). Using an ultrasonic vibration cavitation erosion tester, the alloy showed a mass reduction of 5.9 mg after cavitation-corrosion in a 3.5 wt.% NaCl solution for 10 hours, significantly greater than all other examples (see Table 2). A comprehensive comparison of the microstructure and properties between this comparative example and the examples demonstrates that the simultaneous addition of Co, Ti, and Mo has a more significant regulatory effect on the microstructure than adding Co alone, and simultaneously improves both mechanical properties and cavitation-corrosion resistance.

[0080] Comparative Example 3

[0081] The comparative example describes the preparation of Fe without a multi-level heterostructure using a vacuum arc melting casting process. 29 Ni 34 Cr 20 Al 14Ti3 multi-principal element alloy, the chemical composition of which, by atomic percentage, is: Fe 29%, Ni 34%, Cr 20%, Al 14%, Ti 3%. It should be noted that this alloy can be understood as having zero Co and zero Mo content. The alloy preparation process is the same as in Example 1, and is simplified here: Before batching, the oxide film and impurities on the surface of the raw materials are cleaned. During batching, the atomic ratio is converted into the percentage of each element's mass to the total mass for weighing. The prepared metal raw materials are placed in a crucible, the furnace door is closed, and after vacuuming, an argon atmosphere is purged. Once the required atmosphere is reached, arc melting begins. The melting current is 320A, and the melting is repeated 6 times. Then, it is suction-cast, and after complete cooling, it is removed to obtain Fe. 29 Ni 34 Cr 20 Al 14 Ti3 multi-principal-element alloy.

[0082] Fe in this comparative example 29 Ni 34 Cr 20 Al 14 Phase types and microstructure of Ti3 multi-principal alloys were observed. Figure 4 It can be seen that the alloy exhibits a typical two-phase structure: BCC(B2)+FCC. Figure 6 In the sample, the darker areas represent the BCC phase, and the lighter areas represent the FCC phase. These two phases are intermixed, but the sample does not exhibit the multi-level heterogeneous structure found in similar embodiments. Room temperature tensile results are shown below. Figure 8 As shown, its yield strength is 760 MPa, tensile strength is 1200 MPa, and elongation after fracture is 12.3% (Table 1). Using an ultrasonic vibration cavitation erosion testing machine, the alloy showed a mass reduction of 6.2 mg after cavitation-corrosion in a 3.5 wt.% NaCl solution for 10 hours, significantly greater than all other examples (see Table 2). A comprehensive comparison of the microstructure and properties between this comparative example and the examples demonstrates that the simultaneous addition of Co, Ti, and Mo has a more significant regulatory effect on the microstructure than the addition of Ti alone, and simultaneously improves both mechanical properties and cavitation-corrosion resistance.

[0083] Comparative Example 4

[0084] The comparative example describes the preparation of Fe without a multi-level heterostructure using a vacuum arc melting casting process. 29 Ni 34 Cr 20 Al 14Mo3 multi-principal element alloy, the chemical composition of which, by atomic percentage, is: Fe 29%, Ni 34%, Cr 20%, Al 14%, Mo 3%. It should be noted that this alloy can be understood as having zero Co and zero Ti content. The alloy preparation process is the same as in Example 1, and is simplified here: Before batching, the oxide film and impurities on the surface of the raw materials are cleaned. During batching, the atomic ratio is converted into the percentage of each element's mass to the total mass for weighing. The prepared metal raw materials are placed in a crucible, the furnace door is closed, and after evacuation, an argon atmosphere is purged. Once the required atmosphere is reached, arc melting begins. The melting current is 320A, and the melting is repeated 6 times. Then, it is suction-cast, and after complete cooling, it is removed to obtain Fe. 29 Ni 34 Cr 20 Al 14 Mo3 multi-principal-element alloy.

[0085] Fe in this comparative example 29 Ni 34 Cr 20 Al 14 Phase types and microstructure of Mo3 multi-principal alloys were observed. Figure 4 It can be seen that the alloy exhibits a typical two-phase structure: BCC(B2)+FCC. Figure 6 In the sample, the darker areas represent the BCC phase, and the lighter areas represent the FCC phase. These two phases are intermixed, but the sample does not exhibit the multi-level heterogeneous structure found in similar embodiments. Room temperature tensile results are shown below. Figure 8 As shown, its yield strength is 615 MPa, tensile strength is 1231 MPa, and elongation after fracture is 20.3% (Table 1). Using an ultrasonic vibration cavitation erosion testing machine, the alloy's mass reduction after cavitation-corrosion in a 3.5 wt.% NaCl solution for 10 hours was measured to be 6.4 mg, significantly greater than all other examples (see Table 2). A comprehensive comparison of the microstructure and properties between this comparative example and the examples demonstrates that the simultaneous addition of Co, Ti, and Mo has a more significant regulatory effect on the microstructure than adding Mo alone, and simultaneously improves both mechanical properties and cavitation-corrosion resistance.

[0086] Comparative Example 5

[0087] The comparative example describes the preparation of Fe without a multi-level heterostructure using a vacuum arc melting casting process. 28 Ni 33 Cr 19 Al 14The Co4Ti2 multi-principal element alloy has the following chemical composition (atomic percentage): Fe 28%, Ni 33%, Cr 19%, Al 14%, Co 4%, and Ti 2%. It should be noted that this alloy can be understood as having zero Mo content. The alloy preparation process is the same as in Example 1, but simplified here: Before batching, the oxide film and impurities on the surface of the raw materials are cleaned. During batching, the atomic ratio is converted into the percentage of each element's mass to the total mass for weighing. The prepared metal raw materials are placed in a crucible, the furnace door is closed, and after evacuation, an argon atmosphere is purged. Once the required atmosphere is reached, arc melting begins. The melting current is 320A, and the melting is repeated 6 times. Then, it is suction-cast and removed after complete cooling to obtain Fe. 28 Ni 33 Cr 19 Al 14 Co4Ti2 multi-principal-element alloy.

[0088] Fe in this comparative example 28 Ni 33 Cr 19 Al 14 Phase types and microstructure of Co4Ti2 multi-principal alloy were observed. Figure 5 It can be seen that the alloy exhibits a typical two-phase structure: BCC(B2)+FCC. Figure 7 In the sample, the darker areas represent the BCC phase, and the lighter areas represent the FCC phase. These two phases are intermixed, but the sample does not exhibit the multi-level heterogeneous structure found in similar embodiments. Room temperature tensile results are shown below. Figure 9 As shown, its yield strength is 625 MPa, tensile strength is 1288 MPa, and elongation after fracture is 19.1% (Table 1). Using an ultrasonic vibration cavitation erosion testing machine, the alloy's mass reduction after cavitation-corrosion in a 3.5 wt.% NaCl solution for 10 hours was measured to be 5.6 mg, significantly greater than all other examples (see Table 2). A comprehensive comparison of the microstructure and properties between this comparative example and the examples demonstrates that the simultaneous addition of Co, Ti, and Mo has a more significant regulatory effect on the microstructure than the simultaneous addition of Co and Ti, and simultaneously improves both mechanical properties and cavitation-corrosion resistance.

[0089] Comparative Example 6

[0090] The comparative example describes the preparation of Fe without a multi-level heterostructure using a vacuum arc melting casting process. 28 Ni 33 Cr 18 Al 13The Mo4Ti4 multi-principal element alloy has the following chemical composition (atomic percentage): Fe 28%, Ni 33%, Cr 18%, Al 13%, Mo 4%, and Ti 4%. It should be noted that this alloy can be understood as having zero Co content. The alloy preparation process is the same as in Example 1, but simplified here: Before batching, the oxide film and impurities on the surface of the raw materials are cleaned. During batching, the atomic ratio is converted into the percentage of each element's mass to the total mass for weighing. The prepared metal raw materials are placed in a crucible, the furnace door is closed, and after evacuation, an argon atmosphere is purged. Once the required atmosphere is reached, arc melting begins. The melting current is 320A, and the melting is repeated 6 times. Then, it is suction-cast and removed after complete cooling to obtain Fe. 28 Ni 33 Cr 18 Al 13 Mo4Ti4 multi-principal-element alloy.

[0091] Fe in this comparative example 28 Ni 33 Cr 18 Al 13 Phase types and microstructure of Mo4Ti4 multi-principal element alloy were observed. Figure 5 It can be seen that the alloy exhibits a typical two-phase structure: BCC(B2)+FCC. Figure 7 In the sample, the darker areas represent the BCC phase, and the lighter areas represent the FCC phase. These two phases are intermixed, but the sample does not exhibit the multi-level heterogeneous structure found in similar embodiments. Room temperature tensile results are shown below. Figure 9 As shown, its yield strength is 1142 MPa, tensile strength is 1257 MPa, and elongation after fracture is 1.3% (Table 1). Using an ultrasonic vibration cavitation erosion testing machine, the alloy's mass decreased by 6.2 mg after cavitation-corrosion in a 3.5 wt.% NaCl solution for 10 hours, significantly greater than all other examples (see Table 2). A comprehensive comparison of the microstructure and properties between this comparative example and the examples demonstrates that the simultaneous addition of Co, Ti, and Mo has a more significant regulatory effect on the microstructure than the simultaneous addition of Ti and Mo, and simultaneously improves both mechanical properties and cavitation-corrosion resistance.

[0092] Comparative Example 7

[0093] The comparative example describes the preparation of Fe without a multi-level heterostructure using a vacuum arc melting casting process. 28 Ni 34 Cr 18 Al 14The Co2Mo4 multi-principal element alloy has the following chemical composition (atomic percentage): Fe 28%, Ni 34%, Cr 18%, Al 14%, Co 2%, and Mo 4%. It should be noted that this alloy can be understood as having zero Ti content. The alloy preparation process is the same as in Example 1, but simplified here: Before batching, the oxide film and impurities on the surface of the raw materials are cleaned. During batching, the atomic ratio is converted into the percentage of each element's mass to the total mass for weighing. The prepared metal raw materials are placed in a crucible, the furnace door is closed, and after evacuation, an argon atmosphere is purged. Once the required atmosphere is reached, arc melting begins. The melting current is 320A, and the melting is repeated 6 times. Then, it is suction-cast and removed after complete cooling to obtain Fe. 28 Ni 34 Cr 18 Al 14 Co2Mo4 multi-principal-element alloy.

[0094] Fe in this comparative example 28 Ni 34 Cr 18 Al 14 Phase types and microstructure of Co2Mo4 multi-principal alloy were observed. Figure 5 It can be seen that the alloy exhibits a typical two-phase structure: BCC(B2)+FCC. Figure 7 In the sample, the darker areas represent the BCC phase, and the lighter areas represent the FCC phase. These two phases are intermixed, but the sample does not exhibit the multi-level heterogeneous structure found in similar embodiments. Room temperature tensile results are shown below. Figure 9 As shown, its yield strength is 973 MPa, tensile strength is 1144 MPa, and elongation after fracture is 3.5% (Table 1). Using an ultrasonic vibration cavitation erosion testing machine, the alloy's mass reduction after cavitation-corrosion in a 3.5 wt.% NaCl solution for 10 hours was measured to be 5.7 mg, significantly greater than all other examples (see Table 2). A comprehensive comparison of the microstructure and properties between this comparative example and the examples demonstrates that the simultaneous addition of Co, Ti, and Mo has a more significant regulatory effect on the microstructure than the simultaneous addition of Co and Mo, and simultaneously improves both mechanical properties and cavitation-corrosion resistance.

[0095] Table 1 Summary of room temperature tensile properties of multi-principal element alloys prepared in Examples 1-3 and Comparative Examples 1-7 of the present invention

[0096]

[0097]

[0098] Table 2. Summary of mass loss of multi-principal alloys prepared in Examples 1-3 and Comparative Examples 1-7 of the present invention after 10 h of cavitation-corrosion in 3.5 wt.% NaCl solution.

[0099]

[0100] The above embodiments are preferred embodiments of the present invention, and well-known materials and properties in the solutions are not described in detail. It should be noted that those skilled in the art can make modifications and improvements without departing from the present invention, and these should also be considered within the scope of protection of the present invention. These modifications do not affect the effectiveness and practicality of the present invention. The scope of protection claimed by the present invention should be determined by the claims, and the specific embodiments in the specification can be used to interpret the claims.

Claims

1. A high-ductility, cavitation-erosion-resistant multi-principal-element alloy having a multi-stage heterogeneous structure, characterized by, According to the atomic percentage, the alloy comprises the following components: Fe 27%~32%, Ni 33%~37%, Cr 17%~22%, Al 12%~15%, Co 1%~4%, Ti 1%~4%, and Mo 1%~4%; the phase composition of the multi-principal element alloy comprises a face-centered cubic (FCC) phase and a body-centered cubic (BCC) phase; the morphology of the face-centered cubic (FCC) phase comprises super-fine flake, super-fine rhombus and super-fine vermicular microstructures, and the face-centered cubic (FCC) phase has BCC precipitated phases; the body-centered cubic (BCC) phase has BCC precipitated phases with globular, short rod and labyrinth morphologies formed by spinodal decomposition; The FCC phase and the BCC phase have multiple morphologies, and multiple morphologies of precipitated phases exist in the two phases, finally forming a complex multi-level heterogeneous structure; the FCC phase is rich in Fe-Ni elements, and the BCC phase is rich in Al elements; the cumulative mass loss of the multi-principal element alloy after cavitation-corrosion in a 3.5 wt.% NaCl solution for 10 hours is not higher than 2.6 mg; at room temperature, the tensile yield strength is not lower than 1000 MPa, the ultimate tensile strength is not lower than 1400 MPa, and the elongation after fracture is not lower than 12%.

2. The multi-principal element alloy with multi-stage heterogeneous structure having high strength, toughness, and erosion-corrosion resistance according to claim 1, wherein According to the atomic percentage, the alloy comprises the following components: Fe 27%~32%, Ni 33%~37%, Cr 17%~22%, Al 12%~15%, Co 1%~4%, Ti 1%~4%, and Mo 1%~4%.

3. The multi-principal element alloy with multi-stage heterogeneous structure having high strength, ductility, and erosion-corrosion resistance according to claim 1, wherein According to the atomic percentage, the alloy comprises the following components: Fe 27%~32%, Ni 33%~37%, Cr 17%~22%, Al 12%~15%, Co 1%~4%, Ti 1%~4%, and Mo 1%~4%.

4. The method of producing a high-impact, erosion-corrosion-resistant multi-principal element alloy having a multi-stage heterogeneous structure according to any one of claims 1 to 3, characterized in that, The alloy is prepared by a casting method.

5. The method of claim 4, wherein the method further comprises the step of: The preparation method is vacuum arc melting, comprising the following steps: (1) preparing raw materials according to the atomic percentage of the multi-principal element alloy; (2) vacuum arc melting the raw materials prepared in step (1), and repeating the vacuum arc melting after cooling, and turning over the ingot before each melting; the vacuum arc melting is performed for 4~7 times; (3) melting the ingot in step (2), and suction casting the alloy liquid into a water-cooled copper mold to obtain the multi-principal element alloy with multi-level heterogeneous structure, high strength and toughness, and anti-cavitation-corrosion.

6. The method of claim 5, wherein the method further comprises the step of: The raw materials in step (1) comprise pure metals of Al, Cr, Fe, Ni, Co, Ti and Mo or intermediate alloys comprising Al, Cr, Fe, Ni, Co, Ti and Mo; the purity of the pure metals of Al, Cr, Fe, Ni, Co, Ti and Mo or the intermediate alloys comprising Al, Cr, Fe, Ni, Co, Ti and Mo is higher than 99.9 wt.%.

7. The method of claim 5, wherein the method further comprises the step of: In step (2), the vacuum arc melting parameters are as follows: the arc current is 280~340 A, the vacuum degree is 0.05~0.07 MPa, and the time of each vacuum arc melting is 4~6 min; in step (3), the cooling speed of the water-cooled copper mold is 100~500 K / s. ​ 8. Use of the high strength, high toughness, cavitation-erosion- corrosion resistant multi-principal element alloy having a multi-stage heterogeneous structure according to any one of claims 1 to 3 for the production of a component resistant to cavitation and / or corrosion.

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