ZnAlCu medium-entropy alloy and preparation method thereof

Abstract

The invention relates to the technical field of metal materials, and discloses a ZnAlCu medium-entropy alloy and a preparation method thereof, and in the ZnAlCu medium-entropy alloy, 40 at.% < = Zn < = 75 at.%, 20 at.% < = Al < = 60 at.%, 1 at.% < = Cu < = 5 at. The ZnAlCu medium-entropy alloy provided by the invention has high wear resistance, and has a good prospect in the fields of electric power, mechanical equipment and the like.

Description

Technical Field

[0001] This application relates to the field of metallic materials technology, specifically to ZnAlCu medium-entropy alloys and their preparation methods. Background Technology

[0002] In recent years, the performance optimization of traditional engineering materials (such as alloy steel and nickel-based alloys) has approached its theoretical limit. Their compositional design concepts and microstructure control methods struggle to overcome the "contradictory triangle" of strength, toughness, and corrosion resistance. For example, while increasing the content of alloying elements can improve strength, it often comes at the cost of sacrificing plasticity and machinability. Against this backdrop, developing a new generation of integrated structural and functional materials that combine high strength, high toughness, and fatigue resistance has become crucial for overcoming the technological bottlenecks in engineering equipment. Taking zinc-based alloys as an example, conventional zinc-based alloy materials are no longer sufficient to meet mechanical performance requirements.

[0003] It should be noted that the above statements are only used to provide background information related to this application and do not necessarily constitute prior art. Summary of the Invention

[0004] In a first aspect of this application, a ZnAlCu medium-entropy alloy is proposed, wherein 40 at.% ≤ Zn ≤ 75 at.%, 20 at.% ≤ Al ≤ 60 at.%, and 1 at.% ≤ Cu ≤ 5 at.%.

[0005] In some embodiments, 40 at.% ≤ Zn ≤ 75 at.%, 20 at.% ≤ Al ≤ 60 at.%, and 1 at.% ≤ Cu ≤ 5 at.%.

[0006] In some embodiments, at least one of (1) to (3) below is satisfied:

[0007] (1) The hardness of the ZnAlCu entropy alloy is greater than or equal to HV455;

[0008] (2) The yield strength of the ZnAlCu entropy alloy is greater than or equal to 1003 MPa;

[0009] (3) The ultimate compressive strength of the ZnAlCu medium entropy alloy is greater than or equal to 2450 MPa.

[0010] In a second aspect of this application, a method for preparing the ZnAlCu medium-entropy alloy is provided, comprising: mixing zinc, aluminum, and copper materials to obtain an alloy mixture, wherein the mass ratio of the zinc, aluminum, and copper materials is (49.2-84.6):(14.3-39.6):(1.1-11.2); subjecting the alloy mixture to vacuum arc melting in a protective atmosphere to obtain an alloy ingot, wherein the vacuum arc melting includes several melting and casting processes; and heat-treating the alloy ingot to obtain the ZnAlCu medium-entropy alloy.

[0011] In some embodiments, the current of the vacuum arc melting process is 400A-600A, and the time of a single melting and casting process is 170s-190s.

[0012] In some embodiments, the protective atmosphere includes at least one inert gas, and the vacuum degree of the protective atmosphere is from -0.05 MPa to -0.06 MPa.

[0013] In some embodiments, the temperature of the heat treatment is 900℃-1100℃, the heating rate of the heat treatment is 50℃ / min-70℃ / min, and the holding time of the heat treatment is 60min-70min.

[0014] In a third aspect of this application, another method for preparing the ZnAlCu medium-entropy alloy is proposed, comprising: ball milling zinc powder, aluminum powder, copper powder, and grinding balls in a protective atmosphere to obtain a ball-milled mixture, wherein the purity of each of the zinc powder, aluminum powder, and copper powder is independently greater than or equal to 99.9%; and subjecting the ball-milled mixture to a pre-pressing molding process and a vacuum hot-pressing sintering process in sequence to obtain the ZnAlCu medium-entropy alloy.

[0015] In some embodiments, the vacuum degree of the vacuum hot pressing sintering process is 1×10⁻⁶. -3 Pa-1×10 -4 Pa, the vacuum hot pressing sintering process includes a first sintering section and a second sintering section. The temperature of the first sintering section is 500℃-600℃, and the heating rate of the first sintering section is 5℃ / min-15℃ / min. The temperature of the second sintering section is 900℃-1000℃, the heating rate of the second sintering section is 15℃ / min-25℃ / min, the sintering pressure of the second sintering section is 30MPa-40MPa, and the holding time of the second sintering section is 60min-70min.

[0016] In some embodiments, the pressure of the pre-compression molding process is 300MPa-400MPa, and the time of the pre-compression molding process is 100s-200s.

[0017] In some embodiments, the Dn50 particle size of the zinc powder, the aluminum powder, and the copper powder is 25μm-50μm.

[0018] In some embodiments, the mass ratio of the grinding balls to the ball milling mixture is (5-15):1, the diameter of the grinding balls in the mixed ball milling process is 5mm-10mm; and / or, the ball milling speed in the mixed ball milling process is 250rpm-450rpm; and the mixed ball milling time is 35h-45h.

[0019] The beneficial effects of the technical solution proposed in this application include at least the following:

[0020] Based on zinc-based alloys, this application designs and prepares a medium-entropy alloy composed of zinc, aluminum, and copper, which has high strength and wear resistance. This zinc-based medium-entropy alloy has good prospects in the fields of power and mechanical equipment. Attached Figure Description

[0021] The above and / or additional aspects and advantages of this application will become apparent and readily understood from the description of the embodiments taken in conjunction with the following drawings, in which:

[0022] Figure 1 Metallographic image of the ZnAlCu medium-entropy alloy prepared in Example 1 of this application;

[0023] Figure 2 The image shows the backscattered morphology of the ZnAlCu medium-entropy alloy prepared in Example 1 of this application.

[0024] Figure 3 EDS image of the ZnAlCu medium-entropy alloy prepared in Example 1 of this application;

[0025] Figure 4 The image shows the wear morphology of the ZnAlCu medium-entropy alloy prepared in Example 3 of this application.

[0026] Figure 5 This is a wear cross-sectional view of the ZnAlCu medium-entropy alloy prepared in Example 4 of this application;

[0027] Figure 6 The image shows the compressive stress-strain curve of the ZnAlCu medium-entropy alloy prepared in Example 5 of this application. Detailed Implementation

[0028] The embodiments of this application are described in detail below, with examples of these embodiments shown in the accompanying drawings. However, unnecessary detailed descriptions may be omitted. For example, detailed descriptions of well-known matters and repetitive descriptions of practically identical structures may be omitted. This is to avoid unnecessarily lengthy descriptions and to facilitate understanding by those skilled in the art. Furthermore, the accompanying drawings and the following description are provided to enable those skilled in the art to fully understand this application and are not intended to limit the subject matter of the claims.

[0029] Unless otherwise defined, all technical and scientific terms used in this application have the same meaning as commonly understood by one of ordinary skill in the art to which this application pertains; the terminology used in this application is for the purpose of describing particular embodiments only and is not intended to limit this application; unless otherwise stated, the values ​​of the parameters mentioned in this application can be measured using various measurement methods commonly used in the art (e.g., they can be tested according to the methods given in the embodiments of this application).

[0030] The terms “comprising” and “having”, and any variations thereof, in the specification and claims of this application are open-ended expressions, meaning they include what is specified in this application but do not exclude other aspects.

[0031] In the description of this application, all figures disclosed herein, whether or not the words "approximately" or "about" are used, are approximate values. Each figure may vary by less than 10% or by a difference that is considered reasonable by one of the art, such as 1%, 2%, 3%, 4%, or 5%.

[0032] The "range" disclosed in this application is defined by a lower limit and an upper limit. A given range is defined by selecting a lower limit and an upper limit, which define the boundaries of a particular range. Ranges defined in this way can include or exclude endpoints and can be arbitrarily combined; that is, any lower limit can be combined with any upper limit to form a range. For example, if ranges of 60-120 and 80-110 are listed for a specific parameter, it is expected that ranges of 60-110 and 80-120 are also included. Furthermore, if minimum range values ​​of 1 and 2 are listed, and if maximum range values ​​of 3, 4, and 5 are listed, then the following ranges are all expected: 1-3, 1-4, 1-5, 2-3, 2-4, and 2-5. In this application, unless otherwise stated, the numerical range "ab" represents a shortened representation of any combination of real numbers between a and b, where a and b are real numbers. For example, the numerical range "0-5" indicates that all real numbers between "0-5" have been listed in this article; "0-5" is simply a shortened representation of these numerical combinations. Furthermore, when a parameter is stated as an integer ≥2, it is equivalent to disclosing that the parameter is, for example, an integer such as 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, etc.

[0033] Unless otherwise specified, all embodiments and optional embodiments of this application can be combined to form new technical solutions.

[0034] Unless otherwise specified, all technical features and optional technical features of this application may be combined to form new technical solutions.

[0035] In related technologies, zinc-based alloys are mainly used as non-structural components due to their high strength, such as locking systems, safety components, handles, and accessories. However, existing zinc-based alloy materials are no longer sufficient to meet the requirements of new application scenarios for material mechanical properties. For example, their lower compressive strength and hardness limit their application in load-bearing structural components; poor creep properties result in poor dimensional stability of zinc alloy parts under long-term stress or high-temperature environments, making them prone to deformation and failure.

[0036] In contrast, traditional alloys are often composed of a single main metal, with other elements present in relatively low proportions. These new alloys are multi-principal element alloys, also known as high-entropy alloys (HEA) or medium-entropy alloys (MEA). The difference between high-entropy and medium-entropy alloys lies only in the types and numbers of their principal elements. As the name suggests, high-entropy alloys contain more and more complex elements, but they are both solid solutions and share many similarities in their mechanisms. Generally, high-entropy alloys contain five or more metallic elements in equal atomic ratios, while medium-entropy alloys contain three. High-entropy and medium-entropy alloys exhibit many superior mechanical and physical properties; therefore, multi-principal element alloys with novel design concepts and excellent performance have attracted widespread attention. High-entropy and medium-entropy alloys possess thermodynamic high-entropy effects, structural lattice distortion effects, kinetic slow diffusion effects, and performance cocktail effects. Compared to traditional alloys, multi-principal element alloys exhibit superior properties such as high strength, high toughness, high wear resistance, and high wear resistance. High-entropy alloys have rapidly become a research hotspot in the field of materials science due to their breakthrough multi-principal element design concept and unique performance advantages.

[0037] Therefore, this application designs and prepares a medium-entropy alloy composed of zinc, aluminum, and copper, based on zinc-based alloys. By adjusting the ratio of the principal metal elements, a ZnAlCu medium-entropy alloy with a simple phase structure and excellent strength and wear resistance is developed, and a method for preparing this ZnAlCu medium-entropy alloy is also proposed. The zinc-based medium-entropy alloy with high strength and wear resistance proposed in this application shows promising prospects in the fields of power, machinery, and equipment.

[0038] In a first aspect of this application, a ZnAlCu medium-entropy alloy is proposed, wherein 40 at.% ≤ Zn ≤ 75 at.%, 20 at.% ≤ Al ≤ 60 at.%, and 1 at.% ≤ Cu ≤ 5 at.%. Thus, the ZnAlCu medium-entropy alloy contains a large amount of α-phase aluminum-rich solid solution, which significantly contributes to the strength and wear resistance of the ZnAlCu medium-entropy alloy as a strengthening agent.

[0039] In some embodiments, 40 at.% ≤ Zn ≤ 75 at.%, 20 at.% ≤ Al ≤ 60 at.%, and 1 at.% ≤ Cu ≤ 5 at.%. Thus, the increased volume percentage of the α-phase aluminum-rich solid solution reinforcing phase in the ZnAlCu entropy alloy is beneficial for enhancing the mechanical properties of the ZnAlCu entropy alloy.

[0040] In some embodiments, at least one of (1) to (3) below is satisfied:

[0041] (1) The hardness of the ZnAlCu entropy alloy is greater than or equal to HV455;

[0042] (2) The yield strength of the ZnAlCu entropy alloy is greater than or equal to 1003 MPa;

[0043] (3) The ultimate compressive strength of the ZnAlCu medium entropy alloy is greater than or equal to 2450 MPa.

[0044] Therefore, ZnAlCu medium-entropy alloys have high strength and wear resistance.

[0045] In a second aspect of this application, a method for preparing the aforementioned ZnAlCu medium-entropy alloy is provided, comprising:

[0046] Zinc, aluminum, and copper materials are mixed to obtain an alloy mixture, wherein the mass ratio of zinc, aluminum, and copper is (49.2-84.6):(14.3-39.6):(1.1-11.2). The alloy mixture is then subjected to vacuum arc melting in a protective atmosphere to obtain an alloy ingot, wherein the vacuum arc melting includes several melting and casting processes. The alloy ingot is then heat-treated to obtain the ZnAlCu medium-entropy alloy.

[0047] The method proposed in this application adopts vacuum arc melting combined with heat treatment technology. The consistency of melting can be controlled by real-time monitoring of melting current and vacuum degree, and the mechanical properties can be regulated by changing phase size through heat treatment. The preparation process is reasonable and simple, the preparation process is highly repeatable, and it can realize industrial mass production.

[0048] As an example, zinc, aluminum, and copper materials are placed in a vacuum arc melting furnace, and a roughing pump is used to evacuate the furnace to below 5 Pa, followed by a molecular pump to evacuate the furnace to 1 × 10 Pa. -3 Pa to 1×10 -4 Pa. Then, an inert gas was introduced as a protective atmosphere until the furnace gauge pressure reached -0.05 MPa to -0.06 MPa. Vacuum arc melting was then performed, and the process was repeated 6-8 times. Electromagnetic stirring was simultaneously activated during the melting and casting process until the alloy composition was homogeneous. After melting and casting were completed, the mixture was cooled to room temperature to obtain the ZnAlCu medium-entropy alloy.

[0049] In some embodiments, the current for the vacuum arc melting process is 400A-600A, and the duration of a single melting and casting process is 170s-190s. The aforementioned current magnitude allows the alloy mixture to reach the melting and casting temperature, and the single melting and casting process of the aforementioned duration promotes the mixing and melting of the metals in the alloy mixture. Therefore, the aforementioned temperature change process effectively promotes the mixing and phase transformation of the various metal elements in the alloy mixture, thereby preparing a ZnAlCu medium-entropy alloy.

[0050] In some embodiments, the process further includes: electromagnetically stirring the alloy mixture during the vacuum arc melting process. This promotes thorough mixing of different metallic elements in the alloy mixture, improving the material uniformity of the prepared ZnAlCu medium-entropy alloy.

[0051] In some embodiments, the number of melting and casting processes in the vacuum arc melting treatment is 6-8 times. This facilitates thorough mixing of the various metallic elements in the alloy mixture and promotes crystal transformation.

[0052] In some embodiments, the protective atmosphere includes at least one inert gas, and the vacuum degree of the protective atmosphere is -0.05 MPa to -0.06 MPa. This facilitates the escape of impurity elements from the alloy mixture during the vacuum arc melting process; furthermore, the protective atmosphere can reduce side reactions such as oxidation that occur in the alloy mixture during vacuum arc melting.

[0053] As an example, the protective gas is argon.

[0054] In some embodiments, the heat treatment temperature is 900℃-1100℃, the heating rate is 50℃ / min-70℃ / min, and the holding time is 60min-70min. This is beneficial for improving the structural uniformity and density of the prepared ZnAlCu medium-entropy alloy.

[0055] In a third aspect of this application, another method for preparing the ZnAlCu medium-entropy alloy is proposed, comprising: ball milling zinc powder, aluminum powder, copper powder, and grinding balls in a protective atmosphere to obtain a ball-milled mixture, wherein the purity of each of the zinc powder, aluminum powder, and copper powder is independently greater than or equal to 99.9%; and subjecting the ball-milled mixture to a pre-pressing molding process and a vacuum hot-pressing sintering process in sequence to obtain the ZnAlCu medium-entropy alloy.

[0056] The method proposed in this application involves preparation under vacuum conditions to eliminate oxygen and water vapor. Different metal raw materials are mixed through ball milling, reducing oxidation of aluminum during preparation and minimizing the introduction of pores and inclusions, thereby improving the purity of the prepared ZnAlCu medium-entropy alloy. Vacuum hot-pressing sintering applies unidirectional or bidirectional pressure at high temperatures, promoting close contact between the different metal particles to reduce porosity and obtain a material with near-theoretical density. Therefore, this method offers advantages in improving material density and controlling microstructure.

[0057] As an example, zinc powder, aluminum powder, and copper powder with a purity of 99.9% were initially mixed in a mass ratio of (49.2-84.6):(14.3-39.6):(1.1-11.2). This mixture, along with grinding balls, was then sealed in a stainless steel ball mill jar under an inert gas environment and subjected to high-energy ball milling in a planetary ball mill. Medium-entropy alloy powder was sieved out using a molecular sieve to obtain the ball-milled mixture. The ball-milled mixture was then loaded into a graphite mold, pre-pressed, and then placed and fixed in a vacuum hot-pressing sintering furnace for vacuum hot-pressing sintering treatment, thereby obtaining the ZnAlCu medium-entropy alloy.

[0058] In some embodiments, the vacuum degree of the vacuum hot pressing sintering process is 1×10⁻⁶. -3 Pa to 1×10 -4 The vacuum hot-pressing sintering process includes a first sintering section and a second sintering section. The temperature of the first sintering section is 500℃-600℃, and the heating rate is 5℃ / min-15℃ / min. The temperature of the second sintering section is 900℃-1000℃, the heating rate is 15℃ / min-25℃ / min, the sintering pressure is 30MPa-40MPa, and the holding time is 60min-70min. Performing the vacuum hot-pressing sintering process under the aforementioned vacuum conditions reduces the impact of oxidation side reactions. The slower heating rate of the first sintering section allows sufficient time for metal atoms to diffuse, promoting elemental homogenization and reducing compositional segregation in the prepared ZnAlCu medium-entropy alloy, thereby reducing internal stress and defects in the ZnAlCu medium-entropy alloy. The faster heating rate in the second sintering stage of the vacuum hot pressing sintering process helps to preserve the fine-grained structure in the prepared ZnAlCu medium-entropy alloy and reduce the growth of grains formed in the early stage.

[0059] In some embodiments, the pressure of the pre-compression forming process is 300MPa-400MPa, and the pre-compression forming process time is 100s-200s. The pre-compression forming process uses cold pressing to form a mixture with a certain shape, size, and strength from loose powdered raw materials. This is beneficial for increasing the relative density of the prepared ZnAlCu medium-entropy alloy, shortening the preparation process time, reducing deformation, and also reducing oxidation and contamination of the raw material powder during the preparation process.

[0060] In some embodiments, the Dn50 particle size of the zinc powder, aluminum powder, and copper powder is 25 μm-50 μm. A particle size within this range is beneficial for forming a smaller and more uniform initial pore distribution during vacuum hot pressing sintering, and for producing a denser microstructure in the ZnAlCu medium-entropy alloy prepared after sintering.

[0061] In some embodiments, the mass ratio of the grinding balls to the ball milling mixture is (5-15):1, the diameter of the grinding balls in the mixed ball milling process is 5mm-10mm, and / or the ball milling speed in the mixed ball milling process is 250rpm-450rpm; the mixed ball milling time is 35h-45h. This facilitates the thorough mixing of different metal powders.

[0062] In some embodiments, the prepared ZnAlCu medium-entropy alloy can be surface-treated. This removes external impurities, oxide scale, and burrs from the edges.

[0063] The following specific embodiments illustrate the solution of this application. It should be noted that these embodiments are for illustrative purposes only and should not be considered as limiting the scope of this application. Where specific techniques or conditions are not specified in the embodiments, they are performed according to the techniques or conditions described in the literature in this field or according to the product instructions. Reagents or instruments whose manufacturers are not specified are all conventional products that can be obtained commercially.

[0064] Example 1

[0065] Pure zinc, pure aluminum, and pure copper were weighed out as raw materials according to a mass ratio of 60.6:36.5:3 (atomic percentage of 40:58:2) and mixed to obtain an alloy mixture.

[0066] The mixed gold material was placed in a vacuum melting furnace and evacuated to a vacuum level of 1×10⁻⁶. -3 Pa, fill with 99.99wt.% high-purity argon gas until the gauge pressure inside the furnace is -0.05MPa, and perform vacuum arc melting. Melt and cast for 180s each time at a current of 400A. After casting into an ingot, turn the alloy over. Repeat this melting and casting process 6 times until the composition is uniform. After the melting is completed, cool with the furnace to obtain a ZnAlCu medium-entropy alloy ingot with uniform composition.

[0067] The alloy ingot was placed in a heat treatment furnace and heated to 1000℃ at a rate of 60℃ / min in a high-purity argon atmosphere. It was then held at 1000℃ for 60 min and cooled with the furnace to obtain a ZnAlCu medium-entropy alloy.

[0068] Example 2

[0069] Example 2 is the same as Example 1, except that the mass ratio of pure zinc, pure aluminum and pure copper is 69.5:27.7:2.7 (atomic percentage is 50:48:2); the current of the vacuum arc melting process is 500A and the number of melting and casting times is 7.

[0070] Example 3

[0071] Example 3 is consistent with Example 1, except that the mass ratio of pure zinc, pure aluminum and pure copper is 77.2:20.3:2.5 (atomic percentage is 60:38:2); the current of the vacuum arc melting process is 550A and the number of melting and casting times is 8.

[0072] Example 4

[0073] Zinc powder, aluminum powder, and copper powder with a purity of 99.9% were weighed out according to a mass ratio of 83.7:13.9:2.4 (atomic ratio 70:28:2). After preliminary mixing, they were sealed together with grinding balls in a stainless steel ball mill jar under an inert gas environment and subjected to ball milling in a planetary ball mill. Stainless steel balls with diameters of 5 mm and 10 mm were selected as grinding balls, with a mass ratio of the two types of grinding balls of 1:1 and a mass ratio of grinding balls to powder of 10:1. The mixture was ball-milled at 300 rpm for 40 hours. After ball milling, the powder was sieved out using a molecular sieve and vacuum-preserved to obtain the ball-milled mixture.

[0074] The ball milled mixture was loaded into a graphite mold, and the powder was pre-pressed into shape using a hydraulic press at a pressure of 300 MPa and a pre-pressing time of 120 s. The graphite mold was then placed and fixed in a vacuum hot pressing sintering furnace, and a vacuum degree of 1 × 10⁻⁶ was maintained inside the furnace. -3 The ZnAlCu medium-entropy alloy was subjected to vacuum hot pressing sintering. In the first sintering section, the temperature was increased to 500℃ at a heating rate of 10℃ / min, and in the second sintering section, the temperature was increased to 1000℃ at a heating rate of 20℃ / min. During the process, the sintering pressure was maintained at 30MPa, and the temperature and pressure were held for 1 hour. Then the pressure was released, and the alloy was cooled to room temperature before being taken out.

[0075] Example 5

[0076] Example 5 is consistent with Example 4, except that the mass ratio of zinc powder, aluminum powder and copper powder is 86.7:11:2.3 (atomic percentage ratio 75:23:2); the ball milling speed is 400 rpm and the time is 60 h; the pressure of the pre-pressing process is 400 MPa and the time is 200 s; the temperature of the first sintering section of the vacuum hot pressing sintering process is 600 °C and the pressure of the second sintering section is 40 MPa.

[0077] Test method:

[0078] 1. Microstructure testing

[0079] The surface of the prepared medium-entropy alloy was polished with diamond sandpaper of 600#, 1000#, 1500# and 2000# respectively, and then polished with diamond polishing agent of W2.5 grit. Finally, it was ultrasonically cleaned in deionized water and anhydrous ethanol for 5 min respectively to obtain ZnAlCu medium-entropy alloy block.

[0080] The obtained ZnAlCu medium-entropy alloy was etched with aqua regia after polishing. The microstructure of the ZnAlCu medium-entropy alloy was observed with a metallographic microscope, and the micromorphology of the ZnAlCu medium-entropy alloy was observed with SEM (scanning electron microscope). EDS analysis of the material was also performed.

[0081] 2. Hardness test

[0082] The Vickers hardness of the sample was tested using a Vickers hardness tester under a loading force of 1000g for a holding time of 10s.

[0083] 3. Wear resistance test

[0084] To test the wear resistance of the samples, a silicon nitride ball with a diameter of 3 mm was used. The sample was subjected to linear reciprocating motion on a multi-functional friction and wear testing machine under a normal load of 10 N, a frequency of 2 Hz, a reciprocating stroke of 5 mm, and a sliding time of 30 minutes. During this time, the silicon nitride ball remained stationary while the sample continued to reciprocate. The wear micromorphology was observed using SEM, and the scratch width and depth were calculated using VK-Analyzer software.

[0085] 4. Compression performance test

[0086] To test the compressibility of the sample, the sample was cut into a 5mm×5mm×8mm cuboid using a wire EDM machine. A 100KN universal mechanical testing machine was used, with the compression rate set to 0.005mm / s, and a compressive force was applied along the longitudinal axis of the sample.

[0087] Test results:

[0088] The ZnAlCu medium-entropy alloy prepared in Example 1 was observed to have a microstructure using a metallographic microscope. Figure 1 The microstructure of the ZnAlCu medium entropy alloy was observed using SEM (scanning electron microscopy). Figure 2 Meanwhile, EDS analysis of the material was performed, and the results were obtained. Figure 3 EDS (Energy Dispersive Spectroscopy) analysis showed that a large amount of Al element was enriched in the dark gray phase, making the dark gray phase a brittle and hard phase, thereby increasing the hardness of the ZnAlCu medium entropy alloy.

[0089] The hardness test results are shown in Table 1, which is a graph of the hardness values ​​of the ZnAlCu medium-entropy alloys prepared in any of Examples 1-5. The hardness values ​​are all greater than 455, indicating that the prepared medium-entropy alloys have high hardness and excellent mechanical properties.

[0090] Figure 4The image shows the microstructure of the wear marks on the ZnAlCu medium-entropy alloy prepared in Example 3 after wear resistance testing. The wear marks are shallow and narrow, indicating that the alloy has excellent wear resistance.

[0091] Figure 5 The image shows the wear traces and data obtained after wear resistance testing of the ZnAlCu medium-entropy alloy prepared in Example 4. The maximum depth is 9.98 μm and the pore area is 2568 μm². 2 The maximum height is 0.756 μm, and the vertex area is 9.40 μm. 2 This indicates that the alloy has excellent wear resistance.

[0092] Figure 6 The compressive stress-strain curves of the ZnAlCu medium-entropy alloy prepared in Example 5 were used to test its compressive properties. The calculated yield strength was 1003 MPa and the ultimate compressive strength was 2450 MPa, indicating that the alloy has excellent mechanical properties.

[0093] Table 1

[0094] hardness Example 1 473.9 Example 2 465.4 Example 3 457.4 Example 4 466.3 Example 5 455.8

[0095] In the description of this application, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of technical features indicated. "First feature" and "second feature" may include one or more of the indicated feature.

[0096] In the description of this application, "multiple" and "several" mean two or more.

[0097] In the description of this application, "A and / or B" can include any of the cases of A alone, B alone, or A and B, where A and B are merely examples and can be any technical feature connected by "and / or" in this application.

[0098] In this application, the order in which the steps are written does not imply a strict execution order and does not limit the implementation process. The specific execution order of each step should be determined by its function and possible internal logic. Unless otherwise specified, all steps in this application can be performed sequentially or randomly, preferably sequentially. For example, if the method includes steps (a) and (b), it means that the method may include steps (a) and (b) performed sequentially, or it may include steps (b) and (a) performed sequentially. For example, if the method may also include step (c), it means that step (c) can be added to the method in any order. For example, the method may include steps (a), (b), and (c), or it may include steps (a), (c), and (b), or it may include steps (c), (a), and (b), etc.

[0099] It should be noted that this application is not limited to the above-described embodiments. The above embodiments are merely examples, and any embodiments with the same structure and effect as the technical concept within the scope of this application are included in the technical scope of this application. Furthermore, various modifications that can be conceived by those skilled in the art to the embodiments, and other ways of constructing by combining some of the constituent elements of the embodiments, without departing from the spirit of this application, are also included in the scope of this application.

Claims

1. A ZnAlCu medium-entropy alloy, characterized in that, In the ZnAlCu medium entropy alloy, 40 at.% ≤ Zn ≤ 75 at.%, 20 at.% ≤ Al ≤ 60 at.%, and 1 at.% ≤ Cu ≤ 5 at.%.

2. The ZnAlCu medium-entropy alloy according to claim 1, characterized in that, 40at.%≤Zn≤75at.%, 20at.%≤Al≤60at.%, 1at.%≤Cu≤5at.%.

3. The ZnAlCu medium-entropy alloy according to claim 1, characterized in that, Satisfy at least one of the following (1) to (3): (1) The hardness of the ZnAlCu entropy alloy is greater than or equal to HV455; (2) The yield strength of the ZnAlCu entropy alloy is greater than or equal to 1003 MPa; (3) The ultimate compressive strength of the ZnAlCu medium entropy alloy is greater than or equal to 2450 MPa.

4. A method for preparing the ZnAlCu medium-entropy alloy according to any one of claims 1-3, characterized in that, include: Zinc, aluminum, and copper materials are mixed to obtain an alloy mixture, wherein the mass ratio of zinc, aluminum, and copper is (49.2-84.6):(14.3-39.6):(1.1-11.2). The alloy mixture is subjected to vacuum arc melting in a protective atmosphere to obtain an alloy ingot. The vacuum arc melting process includes several melting and casting processes. The alloy ingot is heat-treated to obtain the ZnAlCu medium-entropy alloy.

5. The method according to claim 4, characterized in that, The vacuum arc melting process uses a current of 400A-600A, and the duration of a single melting and casting process is 170s-190s; and / or, The protective atmosphere includes at least one inert gas, and the vacuum degree of the protective atmosphere is from -0.05 MPa to -0.06 MPa.

6. The method according to claim 4, characterized in that, The heat treatment temperature is 900℃-1100℃, the heating rate is 50℃ / min-70℃ / min, and the holding time is 60min-70min.

7. A method for preparing the ZnAlCu medium-entropy alloy according to any one of claims 1-3, characterized in that, include: In a protective atmosphere, zinc powder, aluminum powder, copper powder, and grinding balls are mixed and ball-milled to obtain a ball-milled mixture, wherein the purity of each of the zinc powder, aluminum powder, and copper powder is independently greater than or equal to 99.9%. The ball-milled mixture is subjected to pre-pressing and vacuum hot-pressing sintering processes in sequence to obtain the ZnAlCu medium-entropy alloy.

8. The method according to claim 7, characterized in that, The vacuum degree of the vacuum hot pressing sintering process is 1×10⁻⁶. -3 Pa to 1×10 -4 Pa, the vacuum hot pressing sintering process includes a first sintering section and a second sintering section, the temperature of the first sintering section is 500℃-600℃, and the heating rate of the first sintering section is 5℃ / min-15℃ / min; The temperature of the second sintering section is 900℃-1000℃, the heating rate of the second sintering section is 15℃ / min-25℃ / min, the sintering pressure of the second sintering section is 30MPa-40MPa, and the holding time of the second sintering section is 60min-70min.

9. The method according to claim 7, characterized in that, The pressure of the pre-compression molding process is 300MPa-400MPa, and the time of the pre-compression molding process is 100s-200s; and / or, The Dn50 particle size of the zinc powder, the aluminum powder, and the copper powder is 25μm-50μm.

10. The method according to claim 7, characterized in that, The mass ratio of the grinding balls to the ball milling mixture is (5-15):1, and the diameter of the grinding balls subjected to the mixed ball milling process is 5mm-10mm; and / or, The ball milling speed for the mixed ball milling process is 250 rpm to 450 rpm; the ball milling time for the mixed ball milling process is 35 h to 45 h.

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