A method for composite variable high-entropy alloy composition design

Abstract

The application relates to the technical field of high-entropy alloy component design, and discloses a method for composite variable high-entropy alloy component design, which comprises the following steps: (1) selecting alloy elements and selecting an alloy element combination according to requirements; (2) taking formation of a single-phase BCC structure as a precondition, confirming the content range of each element according to a single variable method; and (3) setting a variable step, narrowing the content range of each element, and obtaining a high-entropy alloy with a single-phase structure. According to the method of "single variable" and "setting a variable step", the content range of each element in a given element high-entropy alloy is predicted, so that a high-entropy alloy chemical general formula forming a solid solution phase or a single-phase solid solution is obtained, and a parameter calculation value is output, and a parameter change curve is further generated; the method can effectively perform component design of the high-entropy alloy according to a target orientation, directionally obtain a high-entropy alloy with high comprehensive performance, and better meet the requirements of users.

Description

Technical Field

[0001] This invention relates to the field of high-entropy alloy composition design technology, and more specifically to a method for designing high-entropy alloy compositions with composite variables. Background Technology

[0002] High entropy alloys (HEAs) are multi-principal element alloys composed of five or more elements in equimolar or near-equimolar ratios, with each element comprising 5% to 35% of the total atomic mass, capable of forming simple solid solutions. HEAs possess numerous superior properties, including high strength, high hardness, corrosion resistance, wear resistance, high-temperature softening resistance, and oxidation resistance. However, the large number of principal elements and the lack of any phase diagrams for reference in HEAs can lead to suboptimal product performance. Therefore, selecting appropriate elements and determining their proportions to achieve suitable phase composition and prepare novel high entropy alloy systems with superior performance is a key research focus.

[0003] Currently, there are several software programs available for designing high entropy alloy (HEA) compositions using parametric calculation methods, including Thermo-Calc, JMatPro, and CALPHAD.

[0004] Thermo-Calc is a software package that uses thermodynamic and kinetic models to predict the phase stability, phase diagrams, and other properties of multi-component systems. It is primarily used for designing high-entropy alloys with specific properties, such as high-temperature strength and corrosion resistance. JMatPro is another software package that uses thermodynamic and kinetic models to predict the properties of materials, including high-entropy alloys. Its database includes thermodynamic and kinetic data for multi-component systems and can be used to design new HEA compositions. CALPHAD is a phase diagram calculation technique that uses thermodynamic and kinetic models to predict material properties. It is used to design high-entropy alloys with specific properties, such as high-temperature stability and mechanical strength.

[0005] One drawback of these software programs is the lack of reliable thermodynamic and kinetic data for multi-component systems. This leads to inaccurate predictions of HEA (high-entropy alloy) properties, limiting the effectiveness of these programs in designing new HEA compositions. Another shortcoming is the limited understanding of the underlying mechanisms governing the properties of high-entropy alloys. This makes it difficult to accurately predict their properties using existing models and databases. To address these shortcomings, researchers are developing new computational methods that combine machine learning and data mining techniques to generate predictive models for HEA properties. These methods utilize large datasets of experimental and computational data to train models capable of accurately predicting the properties of high-entropy alloys based on their composition.

[0006] In summary, developing a simple, efficient, and highly accurate method for designing high-entropy alloy compositions not only effectively compensates for the shortcomings of existing technologies but also enables effective design of high-entropy alloy compositions and accurate prediction of the phase structure of designed high-entropy alloys, which is of great significance for the widespread application of high-entropy alloys. Summary of the Invention

[0007] The present invention aims to provide a method for designing the composition of composite variable high-entropy alloys, in order to solve the technical problems of low accuracy of phase structure prediction results and inability to perform accurate high-entropy alloy composition design in existing high-entropy alloy composition design methods.

[0008] To achieve the above objectives, the present invention adopts the following technical solution: a method for designing the composition of composite variable high-entropy alloys, comprising the following steps:

[0009] S1. Select alloy elements and choose a combination of alloy elements according to your needs;

[0010] S2. Based on the premise of forming a single-phase structure, determine the content range of each element according to the single variable method;

[0011] S3. Set variable steps to narrow the content range of each element and obtain a high-entropy alloy with a single-phase structure.

[0012] The principles and advantages of this scheme are:

[0013] This method, based on a single-phase structure, determines the content range of each element using a single-variable method and narrows the content range of each element by setting variable steps. This allows for the design of high-entropy alloys with a single-phase BCC structure. This enables the design of high-entropy alloys according to production needs and improves the performance of the produced high-entropy alloys. The inventors discovered that single-phase BCC high-entropy alloys often exhibit higher low-temperature strength and toughness, better high-temperature stability, and better corrosion resistance. First, single-phase BCC high-entropy alloys have a higher dislocation density and a more complex dislocation structure, making them more resistant to deformation and fracture at low temperatures, resulting in higher strength and toughness at low temperatures. In contrast, FCC high-entropy alloys are prone to ductile-brittle transition at low temperatures. Second, the ordered BCC phase formed in single-phase BCC high-entropy alloys at high temperatures is more stable and less prone to grain growth (fineer grains) compared to the ordered FCC phase formed in FCC high-entropy alloys. This allows single-phase BCC high-entropy alloys to maintain their mechanical properties at higher temperatures and exhibit better high-temperature stability. Furthermore, single-phase BCC high-entropy alloys often exhibit better corrosion resistance than FCC high-entropy alloys because the formation of a more protective oxide layer on their surface prevents further corrosion and degradation.

[0014] Preferably, in S2, the method for determining the formation of a single-phase structure includes the following steps:

[0015] Step 1: Calculate the parameter values ​​of the target high-entropy alloy, including the mixing enthalpy (ΔHmix), mixing entropy (ΔSmix), thermodynamic parameter Ω, atomic radius difference (δ), electronegativity difference (Δχ), valence electron concentration (VEC), and theoretical density (ρ).

[0016] Step 2: Compare the parameter values ​​of the target high-entropy alloy with the parameter range of a single-phase solid solution to determine the phase structure of the target high-entropy alloy in a graded manner.

[0017] Preferably, the hierarchical determination includes a first-level determination, a second-level determination, and a third-level determination performed sequentially;

[0018] The first-level judgment is that when the parameters of the target high-entropy alloy fall within the range of δ < 15%, 8.31 J / (K·mol) < ΔSmix, and -40 kJ / mol < ΔHmix ≤ 5 kJ / mol, the target high-entropy alloy is judged to form a solid solution phase. If this judgment is not met, the alloy is deleted.

[0019] The secondary determination is as follows: when the parameters of the target high-entropy alloy fall within the range of δ > 3.3%, -40 kJ / mol < ΔHmix < -7.5 kJ / mol, and Ω < 1, the target high-entropy alloy is determined to form an intermetallic phase, and this part of the data is deleted; when the parameters of the target high-entropy alloy fall within the range of -15 kJ / mol < ΔHmix ≤ 5 kJ / mol, 8.31 J / (K·mol) < ΔSmix ≤ 17.5 J / (K·mol), δ < 3.6%, Ω ≥ 1.1, and VEC < 6.87, the target high-entropy alloy is determined to form a single-phase BCC structure. If this determination is not met, a tertiary determination is performed.

[0020] The three-level judgment is as follows: when the parameters of the target high-entropy alloy fall within the range of Ω≥1.1, δ<3.6%, and VEC>7.3, it is determined that the target high-entropy alloy contains an FCC phase structure. If this judgment is not met, the parameter Δχ is added for the next step of judgment. That is, when the parameters of the target high-entropy alloy fall within the range of -15kJ / mol<ΔHmix≤5kJ / mol, 8.31J / (K·mol)<ΔSmix≤17.5J / (K·mol), Ω≥1.1, VEC<6.87, and Δχ<29%, it is determined that the target high-entropy alloy tends to form a single-phase BCC structure.

[0021] Beneficial effects: This solution improves the accuracy of judgment results by setting up multi-level judgments and gradually narrowing the parameter range. Furthermore, when the conditions are not met after three levels of judgment, an additional parameter Δχ is added for further judgment, effectively reducing the judgment mismatch rate and improving the accuracy of phase structure prediction after high-entropy alloy element design. This enables the design of high-entropy alloy elements and phase structures (performance) according to requirements, reducing raw material trial-and-error costs.

[0022] Preferably, it also includes an exclusion determination, wherein when the parameters of the target high-entropy alloy cannot yield phase structure results based on the first-level determination, the second-level determination, and the third-level determination, the target high-entropy alloy is determined to form a non-single-phase BCC structure.

[0023] Beneficial effects: This solution, by setting up a remedial approach for exclusive judgment, can accommodate all parameter ranges that cannot form a single-phase structure, effectively improving the accuracy of judgment.

[0024] Preferably, in S3, setting the variable step includes the following steps:

[0025] Step (1): Freely set the variable step a. The target high-entropy alloy has n principal elements. Sort the elements A1 to An according to their influence on the alloy properties from largest to smallest. With element A1 as the variable and other elements A2 to An as equal atomic ratios, calculate the content range C1 of A1.

[0026] Step (2): Element A1 takes the initial value C1X0 within C1, element A2 is a variable, and other elements A3 to An are in equal atomic ratios. Calculate the initial range of A2. The value of element A1 is increased by one step C1X0+a, and then another range of values ​​for A2 is calculated. This process is repeated until element A1 reaches the final value within C1. The intersection of the ranges of A2 is the content range C2 of element A2.

[0027] Step (3): Take the initial values ​​C1X0 and C2X0 of elements A1 and A2 respectively within their ranges, and repeat the method in step (2) to obtain the content range C3 of A3; and so on, calculate the content range C4 to Cn of elements A4 to An.

[0028] Beneficial effects:

[0029] 1. This solution uses the methods of "single variable" and "variable step setting" to predict the content range of each element in a given high-entropy alloy, thereby obtaining the general chemical formula of the high-entropy alloy that forms a solid solution phase or a single-phase solid solution. It can also output the calculated parameter values ​​and further generate parameter change curves. It can effectively design the composition of high-entropy alloys according to the target orientation, and obtain high-entropy alloys with high comprehensive performance in a targeted manner, which can better meet the needs of users.

[0030] 2. This scheme can also design high-entropy alloy composition with multiple elements as variables, set variable steps, and predict the content range of variable elements when forming a single-phase solid solution, which greatly reduces the amount of experiments and the cost of trial and error.

[0031] 3. This solution uses, but is not limited to, mixing enthalpy (ΔHmix), mixing entropy (ΔSmix), thermodynamic parameter Ω, atomic radius difference (δ), electronegativity difference (Δχ), valence electron concentration (VEC), and theoretical density (ρ) to predict the phase structure of the target high-entropy alloy, effectively improving product accuracy. The inventors have found through research that the phase structure of the high-entropy alloy predicted by the method in this invention is consistent with the phase structure of the high-entropy alloy obtained by actual production casting, with an accuracy of up to 100%, effectively realizing the customized production of the phase structure of high-entropy alloys.

[0032] 4. This solution can also be applied to the design of multi-principal element alloys, including but not limited to the design of high-entropy alloy composition, determination of alloy phases, determination of alloy crystal structure, and range of alloy element content, which facilitates the prediction of various properties of high-entropy alloys. Attached Figure Description

[0033] Figure 1 This is a flowchart illustrating the multi-level determination process for predicting the phase structure of high-entropy alloys in an embodiment of the present invention.

[0034] Figure 2 In this embodiment of the invention, the chemical formula Al is used. x (Nb3TaTi3Zr) 100-x The curve showing the change of electronegativity difference (Δχ) as Al content changes when Al is the only variable.

[0035] Figure 3 In this embodiment of the invention, the chemical formula Al is used. x (Nb3TaTi3Zr) 100-x When Al is the only variable, the alloy melting point (T) is a parameter. m Curve showing the change in Al content.

[0036] Figure 4 In this embodiment of the invention, the chemical formula Al is used. x (Nb3TaTi3Zr) 100-x The curve showing the change of valence electron concentration (VEC) as a function of Al content when Al is the only variable.

[0037] Figure 5 In this embodiment of the invention, the chemical formula Al is used. x (Nb3TaTi3Zr) 100-x The curve showing the variation of the atomic radius difference (δ) with Al content when Al is the only variable.

[0038] Figure 6 In this embodiment of the invention, the chemical formula Al is used. x (Nb3TaTi3Zr) 100-x The curve showing the change of the enthalpy of mixing (ΔHmix) with the content of Al when Al is the only variable.

[0039] Figure 7 In this embodiment of the invention, the chemical formula Al is used. x (Nb3TaTi3Zr) 100-x The curve of the parameter mixing entropy (ΔSmix) as a function of Al content when Al is the only variable.

[0040] Figure 8 In this embodiment of the invention, the chemical formula Al is used. x (Nb3TaTi3Zr) 100-x The curves showing the change of thermodynamic parameter (Ω) with Al content when Al is the only variable.

[0041] Figure 9 In this embodiment of the invention, the chemical formula Al is used. x (Nb3TaTi3Zr) 100-x The curve showing the variation of the theoretical density (ρ) of the parameter with the Al element content when Al is the only variable.

[0042] Figure 10 In this embodiment of the invention, the chemical formula Mo is used. x (Nb3TaTi3Zr) 100-x The curve showing the change of valence electron concentration (VEC) as a function of Mo content when Mo is the sole variable.

[0043] Figure 11 In this embodiment of the invention, the chemical formula Mo is used. x (Nb3TaTi3Zr) 100-x The curve showing the variation of the atomic radius difference (δ) with the Mo element content when Mo is the only variable.

[0044] Figure 12 In this embodiment of the invention, the chemical formula Mo is used. x (Nb3TaTi3Zr) 100-x The curve showing the change of the electronegativity difference (Δχ) parameter with the Mo element content when Mo is the single variable.

[0045] Figure 13 In this embodiment of the invention, the chemical formula Mo is used. x (Nb3TaTi3Zr) 100-x The curve showing the change of the enthalpy of mixing (ΔHmix) with the content of Mo when Mo is the only variable.

[0046] Figure 14 In this embodiment of the invention, the chemical formula Mo is used. x (Nb3TaTi3Zr) 100-x The curve of the mixing entropy (ΔSmix) as a function of Mo content when Mo is the only variable.

[0047] Figure 15 In this embodiment of the invention, the chemical formula Mo is used. x (Nb3TaTi3Zr) 100-x The curve showing the variation of the theoretical density (ρ) of the parameter with the content of Mo when Mo is the only variable.

[0048] Figure 16 In this embodiment of the invention, the chemical formula Mo is used. x (Nb3TaTi3Zr) 100-x When Mo is the sole variable, the alloy melting point (T) is a parameter. m Curve showing the change in Mo content.

[0049] Figure 17 In this embodiment of the invention, the chemical formula Mo is used. x (Nb3TaTi3Zr) 100-x Curves showing the thermodynamic parameter (Ω) as a function of Mo content when Mo is the sole variable.

[0050] Figure 18 These are the predicted XRD patterns of high-entropy alloys obtained with different Al contents in Examples 1-4 and Comparative Examples 1-3 of this invention.

[0051] Figure 19 The XRD patterns are predicted XRD patterns of high-entropy alloys obtained with different Mo contents in Examples 1, 5-7 and Comparative Example 4 of this invention.

[0052] Figure 20 These are scanning electron microscope (SEM) images of the high-entropy alloy slices after annealing in Examples 3-4 and Comparative Examples 1-3 of this invention. Detailed Implementation

[0053] The present invention will be further described in detail below with reference to embodiments, but the embodiments of the present invention are not limited thereto. Unless otherwise specified, the technical means used in the following embodiments and experimental examples are conventional means well known to those skilled in the art, and the materials, reagents, etc. used are all commercially available. Unless otherwise specified, the technical means used in the following embodiments are conventional means well known to those skilled in the art.

[0054] The existing criteria for predicting the phase structure of high-entropy alloys are as follows:

[0055] The ΔHmix-δ criterion states that when -15 kJ / mol < ΔHmix ≤ 5 kJ / mol; 12 J / (K·mol) < ΔSmix ≤ 17.5 J / (K·mol);

[0056] When δ < 6.5%, high-entropy alloy systems tend to form solid solution phases (proposed by ZHANG et al. in their 2008 article "Solid-solution phase formation rules for multi-component alloys" published in the journal Advanced Engineering Materials).

[0057] The Ω-δ criterion states that if Ω > 1, during alloy solidification, the driving force TmΔSmix for solid solution phase formation is greater than the resistance ΔHmix, and the alloy is more likely to form a solid solution. When Ω < 1, intermetallic compounds will preferentially form. When Ω ≥ 1.1 and δ ≤ 6.6, high-entropy alloys tend to form simple solid solution structures (proposed by YANG et al. in their 2012 article "Prediction of high-entropy stabilized solid solution in multi-component alloys" published in the journal Materials Chemistry and Physics).

[0058] The VEC criterion states that when VEC < 6.87, a BCC solid solution tends to form; when 6.87 < VEC < 8.0, a mixed BCC+FCC solid solution tends to form; and when VEC ≥ 8.0, an FCC solid solution tends to form. (This criterion was proposed by GUO et al. in their 2011 article, "Effect of valence electron concentration onstability of fcc or bcc phase in high-entropy alloys," published in the Journal of Applied Physics).

[0059] However, the predicted results obtained from these criteria are not entirely the same as the phase structure of high-entropy alloys actually produced, resulting in low prediction accuracy. This solution improves the accuracy of phase structure prediction by designing the content range of each element in the high-entropy alloy and then applying a multi-level judgment principle. This facilitates users in designing composite variable high-entropy alloy compositions that meet their performance requirements, greatly reducing the amount of experimentation and material waste.

[0060] Example

[0061] This scheme provides a method for designing the composition of composite variable high-entropy alloys, specifically using Al...x (Nb3TaTi3Zr) 100-x Using high-entropy alloys as a reference, the following steps are included:

[0062] S1. Selection of alloying elements: This scheme specifically uses Al, Nb, Ta, Ti, and Zr as the main alloying elements to design high-entropy alloys;

[0063] S2. Assuming the formation of a single-phase structure, the content range of Al is determined using the single-variable method; Al content is obtained. x (Nb3TaTi3Zr) 100-x The high-entropy alloy obtained in this scheme when the Al content is less than 20% is a single-phase solid solution, which has higher ductility and strength properties and is more in line with actual needs.

[0064] Specifically, the method for determining the formation of a single-phase structure in this scheme includes the following steps:

[0065] Step 1: Calculate the parameter values ​​of the target high-entropy alloy, including the mixing enthalpy (ΔHmix), mixing entropy (ΔSmix), thermodynamic parameter Ω, atomic radius difference (δ), electronegativity difference (Δχ), valence electron concentration (VEC), and theoretical density (ρ).

[0066] The performance parameters of the high-entropy alloy in this scheme include the enthalpy of mixing (ΔH). mix ), Mixed entropy (ΔS) mix ), alloy melting point (T) m Thermodynamic parameters (Ω), atomic radius difference (δ), electronegativity difference (Δχ), valence electron concentration (VEC), and alloy density (ρ), etc., are calculated using the following formulas:

[0067]

[0068] In the formula, c is the enthalpy of mixing of a binary liquid alloy composed of the i-th principal element and the j-th principal element in a regular solution; i or c j It is the atomic content of the i-th principal component or the j-th principal component;

[0069]

[0070] In the formula, R is the ideal gas constant, R = 8.314 J / (K·mol);

[0071]

[0072] In the formula, (T) m ) i Let the melting point be the i-th principal element.

[0073]

[0074]

[0075] In the formula, r i It is the radius of the i-th atom; It is the average radius of the atoms of the alloying elements;

[0076]

[0077] χ i Let be the Pauling electronegativity of the i-th element in the alloy; The average Pauling electronegativity of the alloying elements;

[0078]

[0079] In the formula, (VEC) i Let be the valence electron concentration of the i-th element in the alloy;

[0080]

[0081] In the formula, ρ is the alloy density, ρ i Let A be the density of the i-th principal element. i Let be the relative atomic mass of the i-th principal component.

[0082] Step 2: Compare the parameter values ​​of the target high-entropy alloy with the parameter range of a single-phase solid solution to determine the phase structure of the target high-entropy alloy in a graded manner.

[0083] This tiered judgment process includes sequentially performing Level 1, Level 2, Level 3, and exclusion judgments; including the following methods:

[0084] The first-level judgment is that when the parameters of the target high-entropy alloy fall within the range of δ < 15%, 8.31 J / (K·mol) < ΔSmix, and -40 kJ / mol < ΔHmix ≤ 5 kJ / mol, the target high-entropy alloy is judged to form a solid solution phase. If this judgment is not met, the alloy is deleted.

[0085] The secondary determination is as follows: when the parameters of the target high-entropy alloy fall within the range of δ > 3.3%, -40 kJ / mol < ΔHmix < -7.5 kJ / mol, and Ω < 1, the target high-entropy alloy is determined to form an intermetallic phase, and the data in that range is deleted; when the parameters of the target high-entropy alloy fall within the range of -15 kJ / mol < ΔHmix ≤ 5 kJ / mol, 8.31 J / (K·mol) < ΔSmix ≤ 17.5 J / (K·mol), δ < 3.6%, Ω ≥ 1.1, and VEC < 6.87, the target high-entropy alloy is determined to form a single-phase BCC structure. If the parameters do not meet this determination, a tertiary determination is performed.

[0086] The third-level judgment is as follows: when the parameters of the target high-entropy alloy fall within the range of Ω≥1.1, δ<3.6%, and VEC>7.3, the target high-entropy alloy is judged to contain an FCC phase structure. If this judgment is not met, the parameter Δχ is added for the next step of judgment. That is, when the parameters of the target high-entropy alloy fall within the range of -15kJ / mol<ΔHmix≤5kJ / mol, 8.31J / (K·mol)<ΔSmix≤17.5J / (K·mol), Ω≥1.1, VEC<6.87, and Δχ<29%, the target high-entropy alloy is judged to be prone to forming a single-phase BCC structure.

[0087] The exclusive determination is that when the parameters of the target high-entropy alloy cannot yield the phase structure results based on the first-level determination, second-level determination, and third-level determination, the target high-entropy alloy is determined to form a non-single-phase BCC structure.

[0088] Specifically, the grading determination process is as follows:

[0089] (1) First stage of the program

[0090] Preliminary screening: δ < 15%, 8.31 J / (K·mol) < ΔSmix, -40 kJ / mol < ΔHmix ≤ 5 kJ / mol, delete if not meeting these criteria.

[0091] (2) Second stage of the program

[0092] Intermetallic phase determination: δ > 3.3%, -40 kJ / mol < ΔHmix < -7.5 kJ / mol, Ω < 1. Items meeting these criteria will be deleted.

[0093] Single-phase BCC determination: -15kJ / mol < ΔHmix ≤ 5kJ / mol, 8.31J / (K·mol) < ΔSmix ≤ 17.5J / (K·mol), δ < 3.6%, Ω ≥ 1.1, VEC < 6.87. If this determination is met, the composition is a single-phase BCC alloy. If this determination is not met, proceed to the next step.

[0094] (3) Third stage of the program

[0095] FCC phase determination: Ω≥1.1, δ<3.6%, VEC>7.3. If this determination is met, the alloy composition contains the FCC phase. If this determination is not met, proceed to the next step.

[0096] Single-phase BCC determination: -15kJ / mol < ΔHmix ≤ 5kJ / mol, 8.31J / (K·mol) < ΔSmix ≤ 17.5J / (K·mol), Ω ≥ 1.1, VEC < 6.87, Δχ < 29%. If this determination is met, the composition tends to form a single-phase BCC alloy.

[0097] (4) Fourth stage of the program

[0098] If the above conditions are not met, the output composition is unlikely to form a single-phase BCC alloy, that is, it tends to form a multiphase structure.

[0099] This solution improves the accuracy of judgment results by setting up multi-level judgments and gradually narrowing the parameter range. Furthermore, when the conditions are not met after three levels of judgment, an additional parameter Δχ is added for further judgment, effectively reducing the judgment mismatch rate and improving the accuracy of phase structure prediction after high-entropy alloy element design. This enables the design of high-entropy alloy elements and phase structures (performance) according to requirements, reducing raw material trial-and-error costs.

[0100] S3. Set variable stepping to obtain a high-entropy alloy with a single-phase structure;

[0101] Setting the variable step involves the following steps:

[0102] Step (1) Freely set the variable step a, such as a = 0.001; the target high-entropy alloy has n principal elements. According to experience or other prediction models, sort the elements A1 to An in descending order of their influence on the alloy properties. With element A1 as the variable and other elements A2 to An as equal atomic ratios, calculate the content range C1 of A1.

[0103] Step (2): Element A1 takes the initial value C1X0 within C1, element A2 is a variable, and other elements A3 to An are in equal atomic ratios. Calculate the initial range of A2. The value of element A1 is increased by one step C1X0+a, and then another range of values ​​for A2 is calculated. This process is repeated until element A1 reaches the final value within C1. The intersection of the ranges of A2, C2, is the content range of element A2.

[0104] In step (3), elements A1 and A2 are taken from their starting values ​​C1X0 and C2X0 respectively. The content range C3 of A3 is obtained by repeating the method in step (2). Similarly, the content range C4 to Cn of elements A4 to An is calculated.

[0105] This scheme designs high-entropy alloy compositions with a single element as the variable, predicts the content range of the variable element when forming a single-phase solid solution, outputs the calculated parameter values, and further generates parameter variation curves.

[0106] This scheme uses a parametric calculation method to quickly determine the elemental composition and content, thereby designing a single-phase BCC structure high-entropy alloy material with excellent high-temperature strength and good high-temperature stability, which fully meets the material requirements.

[0107] This approach, by setting variable steps in the manner described above, greatly reduces the amount of experimentation and trial-and-error costs.

[0108] Experimental Example 1: Effects of Compositional Design on High-Entropy Alloys and Verification of Phase Structure of High-Entropy Alloys

[0109] This scheme selects the combination of elements Al / Mo, Nb, Ta, Ti, and Zr (with the general chemical formula Al). x (Nb3TaTi3Zr) 100-x Or Mo x (Nb3TaTi3Zr) 100-x This method employs a single-element variable (specifically, the Al / Mo content) step-by-step variable step approach to design high-entropy alloy composition, obtaining the content range of the variable element when forming a single-phase solid solution. The calculated parameter values ​​are output, and parameter variation curves are further generated (see details). Figures 2-17 By analyzing the variation curves of the combined parameters, the range of Al and Mo content in the high-entropy alloy was determined.

[0110] Specifically, the vacuum arc melting method was used to prepare high-entropy alloys by varying the Al and Mo content in the high-entropy alloys according to gradients of 0%, 5%, 10%, 15%, 20%, 25%, and 30%. The specific composition of the obtained high-entropy alloys is detailed in Table 1.

[0111] The vacuum arc melting method used in this scheme has the following steps:

[0112] Step 1: The raw material is pure metal particles of Al, Nb, Ta, Ti and Zr with a purity of over 99.9%. The raw material is ground to remove surface oxides and then ultrasonically cleaned in anhydrous ethanol.

[0113] Step 2: Then use an electronic balance to weigh the corresponding amount of each element according to the atomic percentage, with a weighing error of ±0.001g;

[0114] Step 3: Place the weighed raw materials into a non-consumable vacuum arc melting furnace for alloying and melting to obtain alloy ingots; before melting the alloy raw materials, the vacuum degree needs to be evacuated to 3×10 -3 ~4×10 -3 Pa (specifically, vacuuming to 3×10 Pa) -3 Then, purge with argon gas to -0.05 to -0.04 MPa (specifically, purge with argon gas to -0.05 MPa);

[0115] Step 4: The alloy ingot is subjected to high-temperature annealing under inert gas protection. The annealing temperature is 1200℃~1400℃ (1200℃ is selected) and the annealing time is 12h~48h (20h is selected). Then it is cooled in the furnace to obtain a high-entropy alloy.

[0116] Table 1 High-entropy alloys with different Al / Mo contents

[0117] Example High-entropy alloys Example 1 <![CDATA[Nb 37.5 Of 12.5 You 37.5 Zr 12.5 ]]> Example 2 <![CDATA[Al5Nb 35.625 Of 11.875 You 35.625 Zr 11.875 ]]> Example 3 <![CDATA[Al 10 Nb 33.75 Of 11.25 You 33.75 Zr 11.25 ]]> Example 4 <![CDATA[Al 15 Nb 31.875 Of 10.625 You 31.875 Zr 10.625 ]]> Comparative Example 1 <![CDATA[Al 20 Nb 30 Of 10 You 30 Zr 10 ]]> Comparative Example 2 <![CDATA[Al 25 Nb 28.125 Of 9.375 You 28.125 Zr 9.375 ]]> Comparative Example 3 <![CDATA[Al 30 Nb 26.25 Of 8.75 You 26.25 Zr 8.75 ]]> Example 5 <![CDATA[Mo5Nb 35.625 Of 11.875 You 35.625 Zr 11.875 ]]> Example 6 <![CDATA[Mo 10 Nb 33.75 Of 11.25 You 33.75 Zr 11.25 ]]> Example 7 <![CDATA[Mo 15 Nb 31.875 Of 10.625 You 31.875 Zr 10.625 ]]> Example 8 <![CDATA[Mo 20 Nb 30 Of 10 You 30 Zr 10 ]]> Example 9 <![CDATA[Mo 25 Nb 28.125 Of 9.375 You 28.125 Zr 9.375 ]]> Comparative Example 4 <![CDATA[Mo 30 Nb 26.25 Of 8.75 You 26.25 Zr 8.75 ]]>

[0118] Based on equations (1) to (8), the parameter values ​​of the high-entropy alloys in Examples 1 to 9 and Comparative Examples 1 to 4 were calculated. The phase structures of the high-entropy alloys in Examples 1 to 9 and Comparative Examples 1 to 4 were predicted according to the multi-level judgment in this scheme. The results are detailed in Table 3. Additionally, as a reference, the XRD spectra of the high-entropy alloys in Examples 1 to 9 and Comparative Examples 1 to 4 were simulated using the Reflex module in Materials Studio software. The results are detailed in Table 3. Figures 18-19 The metallographic images of the high-entropy alloys in Examples 3-4 and Comparative Examples 1-3 after annealing were obtained by scanning electron microscopy (SEM). Figure 20 As shown.

[0119] Table 2 compares the parameter values ​​and predicted phase structures of the high-entropy alloys in Examples 1-9 and Comparative Examples 1-4 with actual results.

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[0121]

[0122] Note: B indicates single-phase BCC, B* indicates a tendency to form single-phase BCC, and F indicates a low likelihood of forming single-phase BCC.

[0123] Table 2 shows that the experimental data, when using the multi-level determination method of composite variables in this scheme to calculate the general chemical formula of the above-mentioned high-entropy alloys, predicts that when the Al content is less than 20% (i.e., x < 20%) and the Mo content is less than 30% (i.e., x < 30%), the target high-entropy alloys will form a single-phase BCC structure or tend to form a single-phase BCC structure. However, when the Al and Mo contents are too high, the calculated parameter values ​​indicate that they tend to form a non-single-phase BCC structure. Moreover, the predicted structure of this scheme is consistent with the actual results, and the prediction accuracy is high.

[0124] Furthermore, such as Figure 20 As shown in the SEM images of the high-entropy alloy slices in Examples 3-4 and Comparative Examples 1-3, Al20, Al25 and Al30 contain parallel-arranged linear bundle structures, Al30 contains elliptical structures, while Al10 and Al15 have relatively uniform structures and do not show multiple phase structures, which is consistent with the predicted results in Table 2.

[0125] This scheme uses parameter calculation methods to quickly determine the elemental composition and content, thereby designing a single-phase BCC structure high-entropy alloy material with excellent high-temperature strength and good high-temperature stability, fully meeting the material requirements.

[0126] Table 3 compares the phase structure and actual results of high-entropy alloys in Examples 1-9 and Comparative Examples 1-4 with the multi-level judgment in this scheme and existing different criteria.

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[0129] Note: B indicates single-phase BCC, B* indicates a tendency to form single-phase BCC, and F indicates a low likelihood of forming single-phase BCC.

[0130] Comparing the results obtained from different criteria in Table 2 with the experimental results, it can be seen that, compared with other criteria, the multi-level judgment method of this scheme can further improve the prediction accuracy of high-entropy alloy phase structure.

[0131] As in Examples 1, 2, and 5, the ΔSmix data is less than 12.5 kJ / mol but greater than 8.31 kJ / mol. In the multi-level judgment rule of this scheme, it meets the judgment principle that "when the parameters of the target high-entropy alloy fall within the range of -15 kJ / mol < ΔHmix ≤ 5 kJ / mol, 8.31 J / (K·mol) < ΔSmix ≤ 17.5 J / (K·mol), δ < 3.6%, Ω ≥ 1.1, and VEC < 6.87, the target high-entropy alloy is judged to form a single-phase BCC structure or tend to form a single-phase BCC structure". Therefore, the high-entropy alloys of Examples 1, 2, and 5 are judged to tend to form a single-phase BCC structure.

[0132] However, the ΔHmix-δ criterion states that "a solid solution phase can only be determined when all parameters satisfy -15kJ / mol < ΔHmix ≤ 5kJ / mol, 12J / (K·mol) < ΔSmix ≤ 17.5J / (K·mol), and δ < 6.5%". Therefore, it would be determined that the high-entropy alloys of Examples 1, 2, and 5 cannot form a solid solution phase, which is completely contrary to the actual results.

[0133] Comparing the prediction results of the high-entropy alloy phase structure of Examples 1, 2, and 5 using the multi-level judgment method of this scheme and the original ΔHmix-δ criterion, it can be seen that when the original ΔHmix-δ criterion is used for judgment, the high-entropy alloy in the range of 8.31 J / (K·mol) < ΔSmix ≤ 12 J / (K·mol) is judged as "unable to form a solid solution phase", which is completely different from the judgment of forming a single-phase BCC structure in this scheme. Moreover, experiments have confirmed that the prediction results of this scheme are consistent with the actual phase structure and have higher prediction accuracy.

[0134] Furthermore, this scheme effectively improves the prediction accuracy of single-phase BCC phase structure by introducing the parameter electronegativity difference (Δχ). For example, in Comparative Example 4, if the Ω-δ criterion is used, i.e., "if Ω > 1, during alloy solidification, the driving force TmΔSmix for solid solution phase formation is greater than the resistance ΔHmix, and the alloy is prone to solid solution formation; when Ω < 1, intermetallic compounds will preferentially form; when Ω ≥ 1.1 and δ ≤ 6.6, high-entropy alloys tend to form simple solid solution structures," then it would be determined that the high-entropy alloy in Comparative Example 4 forms a simple solid solution structure, which is different from the actual result. However, using the multi-level judgment of this scheme, it is determined that the high-entropy alloy in Comparative Example 4 is not prone to forming a single-phase BCC structure, which is the same as the actual result.

[0135] Finally, this scheme combines multiple parameters and a multi-level judgment method to effectively improve the prediction accuracy of multiphase solid solutions. For example, the high-entropy alloys in Comparative Examples 1-4 were judged as multiphase solid solutions by this scheme through multi-level judgment, and their actual experimental results were indeed multiphase solid solutions, a perfect match. However, if the VEC criterion is used, namely "when VEC < 6.87, it tends to form BCC solid solutions; when 6.87 < VEC < 8.0, it tends to form BCC+FCC mixed solid solutions; when VEC ≥ 8.0, it tends to form FCC solid solutions", Comparative Examples 1-4 were all judged to form BCC solid solutions, which is completely different from the actual conclusion of forming multiphase solid solutions.

[0136] The above descriptions are merely embodiments of the present invention, and common knowledge such as specific technical solutions and / or characteristics are not described in detail here. It should be noted that those skilled in the art can make various modifications and improvements without departing from the technical solutions of the present invention, and these should also be considered within the scope of protection of the present invention. These modifications and improvements will not affect the effectiveness of the implementation of the present invention or the practicality of the patent. The scope of protection claimed in this application should be determined by the content of its claims, and the specific embodiments described in the specification can be used to interpret the content of the claims.

Claims

1. A method for composite variable high-entropy alloy composition design, characterized in that: It comprises the following steps: S1, selecting alloy elements, selecting alloy element combination according to requirements; S2, taking forming single-phase structure as premise, confirming content range of each element according to single variable method; The determination method of forming single-phase structure comprises the following steps: Step one, calculating parameter value of target high-entropy alloy, the parameter value includes mixing enthalpy ΔHmix, mixing entropy ΔSmix, thermodynamic parameter Ω, atomic radius difference δ, electronegativity difference Δχ, valence electron concentration VEC and theoretical density ρ; Step two, comparing parameter value of target high-entropy alloy with parameter range of single-phase solid solution, grading determining phase structure of target high-entropy alloy; The grading determination includes first-level determination, second-level determination and third-level determination which are carried out in turn; The first-level determination is that when the parameters of the target high-entropy alloy fall within the range of δ < 15%, 8.31 J / (K·mol) < ΔSmix, -40 kJ / mol < ΔHmix ≤ 5 kJ / mol, it is determined that the target high-entropy alloy forms a solid solution phase, and if it does not meet this determination, it is deleted; The second-level determination is that when the parameters of the target high-entropy alloy fall within the range of δ > 3.3%, -40 kJ / mol < ΔHmix < -7.5 kJ / mol, Ω < 1, it is determined that the target high-entropy alloy forms an intermetallic phase, and this part of data is deleted; and when the parameters of the target high-entropy alloy fall within the range of -15 kJ / mol < ΔHmix ≤ 5 kJ / mol, 8.31 J / (K·mol) < ΔSmix ≤ 17.5 J / (K·mol), δ < 3.6%, Ω ≥ 1.1, VEC < 6.87, it is determined that the target high-entropy alloy forms a single-phase BCC structure, and if it does not meet this determination, third-level determination is carried out; The third-level determination is that when the parameters of the target high-entropy alloy fall within the range of Ω ≥ 1.1, δ < 3.6%, VEC > 7.3, it is determined that the target high-entropy alloy contains an FCC phase structure, and if it does not meet this determination, the parameter Δχ is added for further determination; that is, when the parameters of the target high-entropy alloy fall within the range of -15 kJ / mol < ΔHmix ≤ 5 kJ / mol, 8.31 J / (K·mol) < ΔSmix ≤ 17.5 J / (K·mol), Ω ≥ 1.1, VEC < 6.87, Δχ < 29%, it is determined that the target high-entropy alloy tends to form a single-phase BCC structure; S3, setting variable step, narrowing the content range of each element, and obtaining a high-entropy alloy with a single-phase structure.

2. The method for composition design of complex variable high-entropy alloys according to claim 1, characterized in that: It also includes exclusive determination, which is that when the parameters of the target high-entropy alloy cannot determine the phase structure according to the first-level determination, the second-level determination and the third-level determination, it is determined that the target high-entropy alloy forms a non-single-phase BCC structure.

3. The method for composition design of complex variable high-entropy alloys according to claim 2, wherein: In S3, setting variable step comprises the following steps: Step (1), freely setting variable step a, the target high-entropy alloy has n main elements, sorting A1~An according to the influence of elements on alloy performance from large to small, taking element A1 as a variable, and other elements A2~An as equal atomic ratio, and calculating the content range C1 of A1; Step (2), element A1 takes the starting value C1X0 in C1, element A2 is a variable, and other elements A3-An are equal atomic ratio, and the initial range of A2 is calculated; element A1 takes a value increased by one step C1X0+a, and one A2 value range is calculated, and the cycle is repeated, and when element A1 takes the end value in C1, the intersection of the A2 range is obtained as the content range C2 of element A2; Step (3), element A1 and A2 respectively take the starting value C1X0 and C2X0 in their ranges, and the content range C3 of A3 is obtained by repeating the method in step (2); in this way, the content ranges C4-Cn of elements A4-An are calculated.

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