Mgalczngd light-weight high-entropy alloy material and preparation method thereof

Abstract

The application belongs to the technical field of high-entropy alloy materials, and relates to a MgAlCuZnGd light high-entropy alloy material and a preparation method thereof.The chemical composition of the alloy includes, in atomic percentage, Al: 4.0-4.5 at.%, Cu: 5.0-6.0 at.%, Zn: 5.0-7.0 at.%, Gd: 3.5-5.0 at.%, and the rest is Mg and inevitable impurities.The alloy is prepared by an induction melting method under an inert gas protection atmosphere, metal particles are used as raw materials, and part of elements are prepared by using intermediate alloy particles to obtain a large-size light high-entropy alloy ingot.The high-entropy alloy obtained by the application has the advantages of small density, high strength and simple preparation.

Description

Technical Field

[0001] This invention belongs to the field of high-entropy alloy materials technology, specifically relating to a MgAlCuZnGd lightweight high-entropy alloy material and its preparation method. Background Technology

[0002] In traditional alloy design, a single dominant element typically limits the range of compositions and the potential for novel properties. To meet the growing demand for innovative materials, exploring unconventional alloys, such as high-entropy alloys (HEAs), is essential. HEAs are a new class of multi-principal element alloys that have attracted widespread attention due to their superior properties, including high strength, high hardness, resistance to high-temperature oxidation, and corrosion resistance. Existing research on HEAs mainly focuses on alloys composed of transition metals such as Fe, Co, Ni, Mn, and Cr. However, transition metals have high densities, which cannot meet the lightweight requirements of aerospace and other fields. Lightweight HEAs are characterized by low density and high specific strength, typically using elements with lower density and melting points, such as Mg and Al, as the main alloying elements. However, an excessive number of elements in the alloy composition can lead to complex microstructures and deteriorate the alloy's mechanical properties.

[0003] Traditional methods such as arc melting, induction melting, and mechanical alloying are commonly used in the development of bulk lightweight high-entropy alloys. Arc melting utilizes an electric arc generated between electrodes and the workpiece, or between electrodes themselves, to melt the metal. The melting temperature can be adjusted by the power supply, making it suitable for alloys with high melting temperatures. Induction melting uses eddy currents generated during electromagnetic induction to melt the metal, making it suitable for alloying elements with low melting points and high volatility. Mechanical alloying involves placing metal or alloy powder in a ball mill for extended periods, allowing atomic diffusion in the raw material powder. The alloyed powder is then directly pressed into shape or solidified by sintering to obtain a high-entropy alloy bulk. This method is suitable for preparing high-entropy alloys with significant differences in the melting points of the constituent elements. However, due to the high risk of powder explosion and its inherent instability, coupled with the influence of molds, alloys prepared using mechanical alloying are typically small in size and have simple shapes.

[0004] Therefore, developing lightweight high-entropy alloys with low density, high strength, and simple preparation methods is a pressing problem that needs to be solved in the field of high-entropy alloys. Summary of the Invention

[0005] To address the issue of high specific gravity in existing high-entropy alloys, this invention aims to provide a lightweight high-entropy alloy material with low density, high compressive strength, and good plasticity, as well as its preparation method.

[0006] To achieve the above objectives, the present invention adopts the following technical solution:

[0007] In a first aspect, there is a lightweight high-entropy alloy material of MgAlCuZnGd, wherein the composition of the alloy material by atomic percentage includes: Al: 4.0-4.5 at.%, Cu: 5.0-6.0 at.%, Zn: 5.0-7.0 at.%, Gd: 3.5-5.0 at.%, with the remainder being Mg and unavoidable impurities.

[0008] Furthermore, the density of the alloy material is 2.70 g / cm³. 3 -3.00 g / cm 3 between.

[0009] Secondly, a method for preparing the aforementioned MgAlCuZnGd lightweight high-entropy alloy material specifically includes the following steps:

[0010] Step 1: Weigh the Mg particles, Al particles, Zn particles, Mg-30Gd master alloy particles and Cu-40Zn master alloy particles according to each raw material component;

[0011] Step 2: Using an inert gas as a protective gas, the prepared raw materials are added in order of increasing melting point, including Zn particles, Mg particles, Al particles, Mg-30Gd master alloy particles, and Cu-40Zn master alloy particles, for induction melting to form an alloy slurry; stirring is used to homogenize the raw materials in the alloy slurry to form a molten mixture.

[0012] Step 3: Under an inert gas protective atmosphere, the molten mixture is allowed to stand and then poured into a preheated mold. After solidification and demolding, a MgAlCuZnGd lightweight high-entropy alloy ingot is obtained, which is the MgAlCuZnGd lightweight high-entropy alloy material.

[0013] Furthermore, in step 1, the particle size of the Mg particles is 1 mm to 2 mm, the particle size of the Al particles is 1 mm to 2 mm, the particle size of the Zn particles is 1 mm to 2 mm, the particle size of the Mg-30Gd master alloy particles is 1 mm to 2 mm, and the particle size of the Cu-40Zn master alloy particles is 1 mm to 2 mm.

[0014] Furthermore, in step 1, the purity of the Mg particles, Al particles, Zn particles, Mg-30Gd master alloy particles and Cu-40Zn master alloy particles is ≥99.9 wt.%.

[0015] Furthermore, in step 2, the induction melting temperature is 820℃~870℃.

[0016] Furthermore, in step 2 and / or step 3, the inert gas is an inert gas with a density greater than that of air, used to vent air; preferably, the inert gas is high-purity argon, more preferably, the purity of the high-purity argon is ≥99.999%.

[0017] Furthermore, in step 3, the settling time is 5 to 10 minutes.

[0018] Furthermore, in step 3, the temperature of the preheated mold is 200℃~300℃; and / or, the preheated mold is a preheated graphite mold.

[0019] Compared with the prior art, the present invention has the following beneficial effects:

[0020] 1. This invention relates to a lightweight high-entropy alloy material, MgAlCuZnGd. Mg, an element with low density and a low melting point, is selected as the main alloying element, while Al, Cu, Zn, and Gd are added to form the lightweight high-entropy alloy material. Al, Zn, and Gd primarily function as solid solution strengthening elements in Mg. The strengthening effect increases with increasing Gd atomic percentage (GD) as the GD atomic percentage exceeds 3.5%. When the Gd atomic percentage reaches 5%, the hardness and strength of the alloy are significantly improved. However, if the Gd atomic percentage exceeds 5%, it leads to deterioration of plasticity and brittleness. Although Cu is almost insoluble in Mg, considering that the atomic radius of Cu is relatively similar to that of other elements, adding an appropriate amount of Cu can increase the mixing entropy of the alloy while maintaining a small atomic size mismatch, and can also improve the plasticity of the alloy. The MgAlCuZnGd lightweight high-entropy alloy of this invention has a low density (2.70~3.00 g / cm³). 3 The advantages include high compressive strength (above 400MPa), among which Mg 79.4 Al 4.5 Cu 5.3 Zn 5.8 Gd 5.0 The alloy maintains a moderate plasticity (14.0%) while achieving a compressive strength of up to 474 MPa.

[0021] 2. The preparation method of the MgAlCuZnGd lightweight high-entropy alloy material of the present invention adopts induction melting under an inert gas protective atmosphere, avoiding the potential loss of a large amount of low-melting-point active metal elements such as Mg in the alloy due to arc melting. Furthermore, during preparation, firstly, Gd and Cu are added as raw materials using Mg-30Gd master alloy and Cu-40Zn master alloy, respectively, to lower the melting temperature; secondly, granular raw materials are selected, which helps to accelerate the melting rate of the alloy raw materials and shorten the melting time, thereby reducing the loss of low-melting-point elements; and thirdly, the raw materials are added sequentially in order of increasing melting point, with volatile metal raw materials placed at the bottom and raw materials with higher melting and boiling points placed on top, which can reduce the loss of raw materials. Attached Figure Description

[0022] Figure 1 Mg in Example 1 of this invention 82.1 Al 4.2 Cu 5.1 Zn 5.1 Gd 3.5 XRD patterns;

[0023] Figure 2 Mg in Example 1 of this invention 82.1 Al 4.2 Cu 5.1 Zn 5.1 Gd 3.5 Optical microstructure diagram;

[0024] Figure 3 Mg in Example 2 of the present invention 79.4 Al 4.5 Cu 5.3 Zn 5.8 Gd 5.0 The compressive stress-strain curve. Detailed Implementation

[0025] To make the objectives, technical solutions, and advantages of this invention clearer, the technical solutions of this invention will be clearly and completely described below in conjunction with the embodiments of this invention. The embodiments of this invention are implemented based on the technical solutions of this invention, and detailed implementation methods and processes are given. However, the scope of protection of this invention is not limited to the following embodiments. Those skilled in the art should understand that the embodiments are merely helpful in understanding this invention and should not be considered as specific limitations on this invention. All other embodiments obtained by those skilled in the art based on the embodiments of this invention without creative effort are within the scope of protection of this invention.

[0026] The endpoints and any values ​​of the ranges disclosed in this invention are not limited to the precise ranges or values, and these ranges or values ​​should be understood to include values ​​close to these ranges or values. For numerical ranges, the endpoint values ​​of the various ranges, the endpoint values ​​of the various ranges and individual point values, and individual point values ​​can be combined with each other to obtain one or more new numerical ranges, which should be considered as specifically disclosed in this invention.

[0027] In this invention, unless otherwise specified and / or stated, all numerical values ​​relating to component amounts are "atomic percentages" throughout. Process parameters in the following examples, unless otherwise specified, are generally performed under conventional conditions. The raw materials described in the following examples are all available from publicly available commercial sources.

[0028] According to a first aspect of the present invention, a lightweight high-entropy alloy material of MgAlCuZnGd is provided, wherein the composition of the alloy material, by atomic percentage, comprises: Al: 4.0-4.5 at.%, Cu: 5.0-6.0 at.%, Zn: 5.0-7.0 at.%, Gd: 3.5-5.0 at.%, with the remainder being Mg and unavoidable impurities.

[0029] This invention relates to a lightweight high-entropy alloy material, MgAlCuZnGd. Mg, an element with low density and a low melting point, is selected as the main alloying element, while Al, Cu, Zn, and Gd are added to form a novel lightweight high-entropy alloy material. This material exhibits low density and high specific strength, meeting the lightweight material requirements of aerospace and other fields. Al, Zn, and Gd primarily function as solid solution strengthening elements in Mg. The strengthening effect increases with increasing Gd atomic percentage (ADP) beyond 3.5%. When the ADP ADP reaches 5%, it significantly improves the alloy's hardness and strength. However, exceeding 5% ADP leads to deterioration of plasticity, causing the material to become brittle. Typical, but not limiting, ADP atomic percentages are 4.0 at.%, 4.1 at.%, 4.2 at.%, 4.3 at.%, 4.4 at.%, and 4.5 at.%. Typical but non-limiting atomic percentage contents of Zn are 5.0 at.%, 5.1 at.%, 5.2 at.%, 5.3 at.%, 5.4 at.%, 5.5 at.%, 5.6 at.%, 5.7 at.%, 5.8 at.%, 5.9 at.%, 6.0 at.%, 6.1 at.%, 6.2 at.%, 6.3 at.%, 6.4 at.%, 6.5 at.%, 6.6 at.%, 6.7 at.%, 6.8 at.%, 6.9 at.%, and 7.0 at.%. Typical, but not limiting, atomic percentage contents of Gd are 3.5 at.%, 3.6 at.%, 3.7 at.%, 3.8 at.%, 3.9 at.%, 4.0 at.%, 4.1 at.%, 4.2 at.%, 4.3 at.%, 4.4 at.%, 4.5 at.%, 4.6 at.%, 4.7 at.%, 4.8 at.%, 4.9 at.%, and 5.0 at.%. Although Cu is almost insoluble in Mg, considering that Cu's atomic radius is relatively similar to that of other elements, adding an appropriate amount of Cu can increase the mixing entropy of the alloy while maintaining a small degree of atomic size mismatch, and can also improve the alloy's plasticity. Typical, but non-limiting, atomic percentage contents of Cu are 5.0 at.%, 5.1 at.%, 5.2 at.%, 5.3 at.%, 5.4 at.%, 5.5 at.%, 5.6 at.%, 5.7 at.%, 5.8 at.%, 5.9 at.%, and 6.0 at.%.

[0030] As an optional embodiment of the MgAlCuZnGd lightweight high-entropy alloy material of the present invention, the density of the alloy material is 2.70 g / cm³. 3-3.00 g / cm 3 Between these values, a typical but non-limiting density is 2.70 g / cm³. 3 2.72 g / cm 3 2.74 g / cm 3 2.76 g / cm 3 2.78 g / cm 3 2.80 g / cm 3 2.82 g / cm 3 2.84 g / cm 3 2.86 g / cm 3 2.88 g / cm 3 2.90 g / cm 3 2.92 g / cm 3 2.94 g / cm 3 2.96 g / cm 3 2.98 g / cm 3 3.00 g / cm 3 .

[0031] According to a second aspect of the present invention, a method for preparing the aforementioned MgAlCuZnGd lightweight high-entropy alloy material specifically includes the following steps:

[0032] Step 1: Weigh the Mg particles, Al particles, Zn particles, Mg-30Gd master alloy particles and Cu-40Zn master alloy particles according to each raw material component;

[0033] Step 2: Using an inert gas as a protective gas, the prepared raw materials are added in order of increasing melting point, including Zn particles, Mg particles, Al particles, Mg-30Gd master alloy particles, and Cu-40Zn master alloy particles, for induction melting to form an alloy slurry; stirring, such as electromagnetic stirring, is used to make the raw materials in the alloy slurry uniform, forming a molten mixture.

[0034] Step 3: Under an inert gas protective atmosphere, the molten mixture is allowed to stand and then poured into a preheated graphite mold. After solidification and demolding, a MgAlCuZnGd lightweight high-entropy alloy ingot is obtained, namely the MgAlCuZnGd lightweight high-entropy alloy material.

[0035] The present invention discloses a method for preparing a lightweight high-entropy alloy material MgAlCuZnGd. This method employs induction melting under an inert gas protective atmosphere to avoid the potential loss of low-melting-point reactive metal elements such as Mg due to burn-off during arc melting. Furthermore, the preparation process involves: 1) adding Gd and Cu as Mg-30Gd and Cu-40Zn master alloys, respectively, to lower the melting temperature; 2) selecting granular raw materials to accelerate the melting rate and shorten the melting time, thereby reducing the loss of low-melting-point elements; and 3) adding the raw materials sequentially according to their melting point from low to high, placing volatile metals at the bottom and materials with higher melting and boiling points on top to minimize burn-off.

[0036] The MgAlCuZnGd lightweight high-entropy alloy prepared by this invention has a low density (2.70~3.00 g / cm³). 3 The advantages include high compressive strength (above 400MPa), among which Mg 79.4 Al 4.5 Cu 5.3 Zn 5.8 Gd 5.0 The alloy achieves a compressive strength of 474 MPa while maintaining moderate plasticity (14.0%).

[0037] As an optional embodiment of the preparation method of the present invention, in step 1, the particle size of the Mg particles is 1 mm to 2 mm, the particle size of the Al particles is 1 mm to 2 mm, the particle size of the Zn particles is 1 mm to 2 mm, the particle size of the Mg-30Gd master alloy particles is 1 mm to 2 mm, and the particle size of the Cu-40Zn master alloy particles is 1 mm to 2 mm.

[0038] In the above technical solution, the selected alloy particles have a particle size of 1~2 mm, which can ensure the accuracy of weighing raw materials. The particle size of the alloy particles can typically, but is not limited to, 1 mm, 1.1 mm, 1.2 mm, 1.3 mm, 1.4 mm, 1.5 mm, 1.6 mm, 1.7 mm, 1.8 mm, 1.9 mm, and 2 mm.

[0039] As an optional embodiment of the preparation method of the present invention, in step 1, the purity of the Mg particles, Al particles, Zn particles, Mg-30Gd master alloy particles and Cu-40Zn master alloy particles is ≥99.9 wt.%.

[0040] As an optional embodiment of the preparation method of the present invention, in step 2, the induction melting temperature is 820℃~870℃ (such as 820℃, 825℃, 830℃, 835℃, 840℃, 845℃, 850℃, 855℃, 860℃, 865℃, 870℃, etc.).

[0041] In the above technical solution, the induction temperature is controlled at 820℃~870℃. This avoids both excessively high temperatures, which would increase the burn-off rate of easily oxidized and volatile elements such as Mg and Zn, and excessively low temperatures, which might make it difficult to melt the high-melting-point Cu-40Zn alloy (melting point around 900℃).

[0042] As an optional embodiment of the preparation method of the present invention, in step 2 and / or step 3, the inert gas is an inert gas with a density greater than that of air, used to vent air; preferably, the inert gas is high-purity argon, and more preferably, the purity of the high-purity argon is ≥99.999%.

[0043] As an optional embodiment of the preparation method of the present invention, in step 3, the standing time is 5~10min (e.g., 5min, 6min, 7min, 8min, 9min, 10min, etc.).

[0044] As an optional embodiment of the preparation method of the present invention, in step 3, the temperature of the preheated mold is 200℃~300℃ (such as 200℃, 210℃, 220℃, 230℃, 240℃, 250℃, 260℃, 270℃, 280℃, 290℃, 300℃, etc.).

[0045] In the above technical solution, mold preheating can improve the surface quality of the casting. Extensive experiments have shown that the preheating temperature within this range is suitable, resulting in better casting formation. Conversely, an unheated mold will cause the molten metal to cool too quickly, reducing its fluidity and making the casting prone to problems such as incomplete forming, inclusions, and severe segregation.

[0046] As an optional embodiment of the preparation method of the present invention, in step 3, the preheating mold is a preheated graphite mold.

[0047] Example 1

[0048] In this embodiment, the lightweight high-entropy alloy is Mg. 82.1 Al 4.2 Cu 5.1 Zn 5.1 Gd 3.5 .

[0049] The preparation method used for the lightweight high-entropy alloy in this embodiment specifically includes the following steps:

[0050] Step 1: According to Mg82.1 Al 4.2 Cu 5.1 Zn 5.1 Gd 3.5 The chemical composition was calculated for batching, and Mg, Al, Zn, Mg-30Gd master alloy and Cu-40Zn master alloy particles with a purity of ≥99.9 wt.% were weighed. For Mg and Zn elements that are easily oxidized and volatile, the burn-off rate should be considered in the batching calculation. When configuring raw materials according to the molar ratio, Mg and Zn elements were added by 5% more each in this embodiment.

[0051] Step 2: Add the prepared raw materials in order of increasing melting point, including Zn, Mg, Al, Mg-30Gd master alloy, and Cu-40Zn master alloy particles, into the melting crucible. Place the more volatile metals at the bottom and the materials with higher melting and boiling points on top to reduce material loss during burning. Simultaneously, introduce high-purity argon gas (≥99.999% purity) as a protective gas. Induction melt the raw materials in the crucible to 850℃ and hold until all components are completely melted. Use electromagnetic stirring to homogenize the raw materials and form a molten mixture.

[0052] Step 3: Under a protective atmosphere of high-purity argon, the molten mixture is allowed to stand for 10 minutes, then poured into a graphite mold preheated to 200°C. After solidification and demolding, Mg is obtained. 82.1 Al 4.2 Cu 5.1 Zn 5.1 Gd 3.5 Lightweight high-entropy alloy ingot.

[0053] Figure 1 The XRD pattern of the alloy in the as-cast state shows that the microstructure of the alloy mainly includes α-Mg, Al2Gd phase, MgCuZn phase and Mg2Cu phase. Figure 2 This image shows the microstructure of the as-cast lightweight high-entropy alloy in this embodiment under an optical microscope. The as-cast grains are uniformly distributed, with the white phase being the Al₂Gd phase, which strengthens the alloy's mechanical properties. The alloy has a density of only 2.78 g / cm³. 3 The compressive strength is significantly lower than that of traditional high-entropy alloys composed of elements such as Ni, Fe, Co, Cr, and Mn. The room-temperature compressive properties of this alloy in its as-cast state were tested using an electronic universal testing machine (WDW-100E). The compressive strength at room temperature reached 404 MPa, and the fracture strain was 13.9%.

[0054] Example 2

[0055] In this embodiment, the lightweight high-entropy alloy is Mg. 79.4 Al 4.5 Cu 5.3 Zn 5.8 Gd5.0 .

[0056] The preparation method used for the lightweight high-entropy alloy in this embodiment specifically includes the following steps:

[0057] Step 1: According to Mg 79.4 Al 4.5 Cu 5.3 Zn 5.8 Gd 5.0 The chemical composition was calculated for batching, and Mg, Al, Zn, Mg-30Gd master alloy and Cu-40Zn master alloy particles with a purity of ≥99.9 wt.% were weighed. For Mg and Zn elements that are easily oxidized and volatile, the burn-off rate should be considered in the batching calculation. When configuring raw materials according to the molar ratio, Mg and Zn elements were added by 5% more each in this embodiment.

[0058] Step 2: Add the prepared raw materials in order of increasing melting point, including Zn, Mg, Al, Mg-30Gd master alloy, and Cu-40Zn master alloy particles, into the melting crucible. Place the more volatile metals at the bottom and the materials with higher melting and boiling points on top to reduce material loss during burning. Simultaneously, introduce high-purity argon gas (≥99.999% purity) as a protective gas. Induction melt the raw materials in the crucible to 850℃ and hold until all components are completely melted. Use electromagnetic stirring to homogenize the raw materials and form a molten mixture.

[0059] Step 3: Under a protective atmosphere of high-purity argon, the molten mixture is allowed to stand for 10 minutes, then poured into a graphite mold preheated to 200°C. After solidification and demolding, Mg is obtained. 79.4 Al 4.5 Cu 5.3 Zn 5.8 Gd 5.0 Lightweight high-entropy alloy ingot.

[0060] The density of this alloy is 2.96 g / cm³. 3 The room temperature compressive properties of the alloy in its as-cast state were tested using an electronic universal testing machine (WDW-100E). The compressive strength at room temperature can reach 474 MPa, and the fracture strain is 14.0%. Figure 3 This is the room temperature compressive stress-strain curve of the alloy.

[0061] Example 3

[0062] In this embodiment, the lightweight high-entropy alloy is Mg. 79.1 Al 4.5 Cu 5.9 Zn 6.9 Gd 3.6 .

[0063] The preparation method used for the lightweight high-entropy alloy in this embodiment specifically includes the following steps:

[0064] Step 1: According to Mg 79.1 Al 4.5 Cu 5.9 Zn 6.9 Gd 3.6 The chemical composition was calculated for batching, and Mg, Al, Zn, Mg-30Gd master alloy and Cu-40Zn master alloy particles with a purity of ≥99.9 wt.% were weighed. For Mg and Zn elements that are easily oxidized and volatile, the burn-off rate should be considered in the batching calculation. When configuring raw materials according to the molar ratio, Mg and Zn elements were added by 5% more each in this embodiment.

[0065] Step 2: Add the prepared raw materials in order of increasing melting point, including Zn, Mg, Al, Mg-30Gd master alloy, and Cu-40Zn master alloy particles, into the melting crucible. Place the more volatile metals at the bottom and the materials with higher melting and boiling points on top to reduce material loss during burning. Simultaneously, introduce high-purity argon gas (≥99.999% purity) as a protective gas. Induction melt the raw materials in the crucible to 850℃ and hold until all components are completely melted. Use electromagnetic stirring to homogenize the raw materials and form a molten mixture.

[0066] Step 3: Under a protective atmosphere of high-purity argon, the molten mixture is allowed to stand for 10 minutes, then poured into a graphite mold preheated to 200°C. After solidification and demolding, Mg is obtained. 79.1 Al 4.5 Cu 5.9 Zn 6.9 Gd 3.6 Lightweight high-entropy alloy ingot.

[0067] The density of this alloy is 2.79 g / cm³. 3 The room temperature compressive properties of the alloy in its as-cast state were tested using an electronic universal testing machine (WDW-100E). The compressive strength at room temperature reached 441 MPa, and the fracture strain was 14.8%.

[0068] Comparative Example 1

[0069] The comparative example of a lightweight, high-entropy alloy is Mg. 81.2 Al 4.1 Cu 7.0 Zn 4.7 Gd 3.0 The preparation method and steps provided in this comparative example are the same as those in Example 1. The density of this alloy is 2.78 g / cm³. 3The room temperature compressive properties of this alloy in the as-cast state were tested using an electronic universal testing machine (WDW-100E). The compressive strength at room temperature reached 340 MPa, and the fracture strain was 8.1%. This comparative example Mg... 81.2 Al 4.1 Cu 7.0 Zn 4.7 Gd 3.0 The alloy composition is the same as that of Mg in Example 1. 82.1 Al 4.2 Cu 5.1 Zn 5.1 Gd 3.5 Compared to the alloy, the percentage of Cu atoms is significantly increased to 7.0%. Cu is almost insoluble in Mg, so the excessive Cu atoms tend to form a large number of Mg2Cu and MgCuZn compounds. These compounds grow alternately near the grain boundaries to form a coarse network structure, which leads to the deterioration of plasticity.

[0070] Comparative Example 2

[0071] The comparative example of a lightweight, high-entropy alloy is Mg. 79.3 Al 4.5 Cu 5.3 Zn 5.7 Gd 5.2 The preparation method and steps provided in this comparative example are the same as those in Example 2. The density of this alloy is 3.12 g / cm³. 3 The room temperature compressive properties of this alloy in the as-cast state were tested using an electronic universal testing machine (WDW-100E). The compressive strength at room temperature reached 402 MPa, and the fracture strain was 6.5%. This comparative example Mg... 79.3 Al 4.5 Cu 5.3 Zn 5.7 Gd 5.2 The alloy composition is the same as that of Mg in Example 2. 79.4 Al 4.5 Cu 5.3 Zn 5.8 Gd 5.0 Compared to the alloy, the atomic percentage of Gd has increased to 5.2%, but the further increase in Gd has not significantly improved the strength of the alloy. Instead, it leads to the easy formation of clusters, causing deterioration of plasticity and making the material brittle.

[0072] Comparative Example 3

[0073] The comparative example of a lightweight, high-entropy alloy is Mg. 78.2 Al 4.5 Cu 5.8 Zn 8.0 Gd 3.5The preparation method and steps provided in this comparative example are the same as those in Example 3. The density of this alloy is 2.95 g / cm³. 3 The room temperature compressive properties of this alloy in the as-cast state were tested using an electronic universal testing machine (WDW-100E). The compressive strength at room temperature reached 398 MPa, and the fracture strain was 9.2%. This comparative example Mg... 78.2 Al 4.5 Cu 5.8 Zn 8.0 Gd 3.5 The alloy composition is the same as that of Mg in Example 3. 79.1 Al 4.5 Cu 5.9 Zn 6.9 Gd 3.6 Compared to the alloy, the atomic percentage of Zn element is significantly increased to 8.0%. On the one hand, a small amount of Zn dissolves in Mg, causing lattice distortion. On the other hand, Zn element, Mg, and Cu elements form a large amount of MgCuZn compound around the grain boundaries. The higher Zn content weakens the formation of Mg2Cu phase. Furthermore, excessive Zn element can also form (Mg, Zn)3Gd phase with Mg and Gd elements, which connects with the MgCuZn phase, leading to a decrease in plasticity.

[0074] Comparative Example 4

[0075] The comparative example of a lightweight, high-entropy alloy is Mg. 79.2 Al 7.0 Cu 5.0 Zn 5.3 Gd 3.5 The preparation method and steps provided in this comparative example are the same as those in Example 1. The density of this alloy is 2.80 g / cm³. 3 The room temperature compressive properties of this alloy in the as-cast state were tested using an electronic universal testing machine (WDW-100E). The compressive strength at room temperature reached 385 MPa, and the fracture strain was 9.8%. This comparative example Mg... 79.2 Al 7.0 Cu 5.0 Zn 5.3 Gd 3.5 The alloy composition is the same as that of Mg in Example 1. 82.1 Al 4.2 Cu 5.1 Zn 5.1 Gd 3.5Compared to other alloys, the atomic percentage of Al is significantly increased, reaching 7.0%. Although Al has a high solid solubility in Mg, the ideal enthalpy of mixing between Al and Gd is -39 kJ / mol. Al₂Gd compounds exhibit strong phase structure stability; when the Al content is too high, the proportion of the Al₂Gd phase increases, and it is distributed in needle-like patterns within the Mg matrix and the MgCuZn phase, enhancing the alloy's strength and hardness. However, due to the excessive presence of the hard and brittle Al₂Gd phase, the alloy's plasticity decreases significantly.

[0076] Comparative Example 5

[0077] The comparative example of a lightweight, high-entropy alloy is Mg. 84.0 Al 4.0 Cu 4.5 Zn 4.7 Gd 2.8 The preparation method and steps provided in this comparative example are the same as those in Example 1. The density of this alloy is 2.85 g / cm³. 3 The room temperature compressive properties of this alloy in the as-cast state were tested using an electronic universal testing machine (WDW-100E). The compressive strength at room temperature reached 368 MPa, and the fracture strain was 11.2%. Comparative Example 5: Mg 84.0 Al 4.0 Cu 4.5 Zn 4.7 Gd 2.8 The alloy composition is the same as that of Mg in Example 1. 82.1 Al 4.2 Cu 5.1 Zn 5.1 Gd 3.5 Compared to the alloy, the atomic percentages of Cu, Zn, and Gd are all reduced. Although the atomic percentage of Al has increased to some extent, the content of the second phases Al2Gd and MgCuZn is low, so their strengthening effect on the alloy is not ideal.

[0078] Comparative Example 6

[0079] The comparative example of a lightweight, high-entropy alloy is Mg. 82.2 Al 4.0 Cu 5.1 Zn 5.4 Gd 3.3 The preparation method and steps provided in this comparative example are the same as those in Example 1. The density of this alloy is 2.83 g / cm³. 3 The room temperature compressive properties of this alloy in the as-cast state were tested using an electronic universal testing machine (WDW-100E). The compressive strength at room temperature reached 351 MPa, and the fracture strain was 9.43%. (Comparative Example 6: Mg...) 82.2 Al 4.0 Cu 5.1 Zn5.4 Gd 3.3 The alloy composition is the same as that of Mg in Example 1. 82.1 Al 4.2 Cu 5.1 Zn 5.1 Gd 3.5 Compared to the alloy, the Gd atomic percentage is less than 3.5 at.%, because most Gd preferentially combines with Al to form the Al2Gd phase during solidification, only a small number of Gd atoms contribute to solid solution strengthening. Mg 82.2 Al 4.0 Cu 5.1 Zn 5.4 Gd 3.3 The compressive strength of the alloy is significantly lower than that of Example 1.

[0080] The above description is merely a specific embodiment of the present invention and not a limitation thereof. Any variations or substitutions that can be easily conceived by those skilled in the art within the scope of the technology disclosed in this invention should be included within the protection scope of this invention. Therefore, the protection scope of this invention should be determined by the scope of the claims.

Claims

1. A lightweight high-entropy alloy material of MgAlCuZnGd, characterized in that, The alloy material composition, expressed in atomic percentage, includes: Al: 4.0-4.5 at.%, Cu: 5.0-6.0 at.%, Zn: 5.0-7.0 at.%, Gd: 3.5-5.0 at.%, with the remainder being Mg and unavoidable impurities.

2. The MgAlCuZnGd lightweight high-entropy alloy material according to claim 1, characterized in that, The density of the alloy material is 2.70 g / cm³. 3 -3.00 g / cm 3 between.

3. A method for preparing a MgAlCuZnGd lightweight high-entropy alloy material according to any one of claims 1-2, characterized in that, Includes the following steps: Step 1: Weigh the Mg particles, Al particles, Zn particles, Mg-30Gd master alloy particles and Cu-40Zn master alloy particles according to each raw material component; Step 2: Using an inert gas as a protective gas, the prepared raw materials are added in order of increasing melting point, including Zn particles, Mg particles, Al particles, Mg-30Gd master alloy particles, and Cu-40Zn master alloy particles, for induction melting to form an alloy slurry; stirring is used to homogenize the raw materials in the alloy slurry to form a molten mixture. Step 3: Under an inert gas protective atmosphere, the molten mixture is allowed to stand and then poured into a preheated mold. After solidification and demolding, a MgAlCuZnGd lightweight high-entropy alloy ingot is obtained, which is the MgAlCuZnGd lightweight high-entropy alloy material.

4. The preparation method according to claim 3, characterized in that, In step 1, the particle size of the Mg particles is 1mm-2mm, the particle size of the Al particles is 1mm-2mm, the particle size of the Zn particles is 1mm-2mm, the particle size of the Mg-30Gd master alloy particles is 1mm-2mm, and the particle size of the Cu-40Zn master alloy particles is 1mm-2mm.

5. The preparation method according to claim 3, characterized in that, In step 1, the purity of the Mg particles, Al particles, Zn particles, Mg-30Gd master alloy particles and Cu-40Zn master alloy particles is ≥99.9 wt.%.

6. The preparation method according to claim 3, characterized in that, In step 2, the induction melting temperature is 820℃~870℃.

7. The preparation method according to claim 3, characterized in that, In step 2, the induction melting time is 15-20 minutes.

8. The preparation method according to claim 3, characterized in that, In step 2 and / or step 3, the inert gas is an inert gas with a density greater than that of air, used to vent air.

9. The preparation method according to claim 8, characterized in that, The inert gas is high-purity argon.

10. The preparation method according to claim 9, characterized in that, The purity of the high-purity argon gas is ≥99.999%.

11. The preparation method according to claim 3, characterized in that, In step 3, the settling time is 5 to 10 minutes.

12. The preparation method according to claim 3, characterized in that, In step 3, the temperature of the preheated mold is 200℃~300℃; And / or, the preheated mold is a preheated graphite mold.

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