A method for predicting long-period stacking-ordered magnesium-rare earth alloy and application thereof

Abstract

The application relates to a long-period stacking-ordered magnesium-rare earth alloy prediction method and application thereof, and belongs to the technical field of metal materials. The prediction method comprises the following steps: liquid structure models of pure Mg, binary Mg-RE alloy, ternary Mg-RE-X (X is other alloy elements) alloy and single atom models of each alloy element are respectively constructed; through molecular dynamics simulation and first principle calculation, the volume, cohesive energy, chemical short program parameters and proportion of each local structure symmetry of the above models are obtained; according to the evolution trend of the volume and cohesive energy of the ternary Mg-RE-X alloy relative to the binary Mg-RE alloy, the consistency of the distribution state of the chemical short program characteristics and the proportion of each local structure symmetry evolved from the binary Mg-RE alloy and pure Mg, effective prediction of whether a long-period stacking-ordered phase can be formed in the Mg-RE-X alloy is realized. Through theoretical calculation, element design basis for development of the long-period stacking-ordered magnesium-rare earth alloy is provided, and the blindness of alloy design is reduced.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of metal materials, and particularly relates to a prediction method of long-period stacking ordered magnesium-rare earth alloy and application thereof. BACKGROUND

[0002] The information disclosed in this Background section is only for the purpose of increasing an understanding of the general background of the application and does not necessarily constitute an admission or a recognition that the information forms part of the prior art that is already known in any country in the world.

[0003] As a light metal material, magnesium alloy has high specific strength, high specific stiffness, good thermal and electrical conductivity, good electromagnetic shielding property, and easy recycling, and has a wide application prospect in the fields of transportation, aerospace, 3C industry, etc. However, the large-scale commercial application of magnesium alloy still faces many obstacles such as low absolute strength, poor deformability, and weak corrosion resistance.

[0004] Long-period stacking ordered phase is a newly discovered effective strengthening and toughening phase in magnesium-rare earth alloy, which can significantly improve the strength, elongation, creep resistance and corrosion resistance of the alloy. Therefore, it is of great significance to break through the application obstacles of magnesium alloy by designing a wide range of long-period stacking ordered magnesium-rare earth alloy for long-period stacking ordered phase.

[0005] For the problem of which alloying elements can introduce long-period stacking ordered phase in magnesium-rare earth alloy, some documents have summarized the characteristics of alloying elements in Mg-RE-X (X is other alloying elements) alloy containing long-period stacking ordered phase, but the characteristics summarized are not accurately described, and it is difficult to integrate these characteristics into a prediction method of long-period stacking ordered magnesium-rare earth alloy for alloy design. Therefore, it is necessary to establish the correspondence between the alloying element combination in Mg-RE-X alloy and the formation of long-period stacking ordered phase by means of theoretical calculation, so as to form a clear and reliable prediction method. This is of great significance to improve the efficiency of magnesium alloy design for long-period stacking ordered phase. SUMMARY

[0006] In order to solve the above technical problems, the application provides a prediction method of long-period stacking ordered magnesium-rare earth alloy, which mainly obtains the liquid structure characteristics of Mg-RE-X alloy by molecular dynamics simulation and first-principle calculation, and establishes the relationship between the structure characteristics and pure Mg and binary Mg-RE alloy, so as to realize the prediction of long-period stacking ordered magnesium-rare earth alloy.

[0007] In order to achieve the above technical purpose, the application provides the following solutions:

[0008] In a first aspect of the present application, a prediction method of long-period stacking-ordered magnesium-rare earth alloy is provided, and the prediction method comprises the following steps:

[0009] (1) Construct liquid structure models of pure Mg, binary Mg-RE alloy, ternary Mg-RE-X alloy and single atom models of alloy elements respectively;

[0010] (2) Obtain the volume, cohesive energy, chemical short program parameters and local structure symmetry proportion of pure Mg, binary Mg-RE alloy and ternary Mg-RE-X alloy through molecular dynamics simulation and first principle calculation, analyze the evolution trend of the volume and cohesive energy of the ternary Mg-RE-X alloy relative to the binary Mg-RE alloy, the chemical short program characteristics and the distribution state of the local structure symmetry proportion evolved from the binary Mg-RE alloy, and the consistency with pure Mg.

[0011] In a second aspect of the present application, the prediction method of long-period stacking-ordered magnesium-rare earth alloy is applied in the field of alloy design.

[0012] In a third aspect of the present application, an alloy design method capable of effectively introducing long-period stacking-ordered phase in a magnesium alloy is provided, and the alloy design method comprises the prediction method of long-period stacking-ordered magnesium-rare earth alloy.

[0013] In a fourth aspect of the present application, a long-period stacking-ordered Mg-RE-X alloy obtained through the prediction method is provided, and the long-period stacking-ordered Mg-RE-X alloy comprises Mg-Y-Ga, Mg-Y-Ru, Mg-Y-Rh, Mg-Y-Pd, Mg-Y-Ir, Mg-Y-Pt and Mg-Y-Au alloy.

[0014] The present application has the following beneficial effects:

[0015] (1) The prediction method can predict whether various elements can introduce long-period stacking-ordered phase in a magnesium alloy through theoretical calculation, provide composition design basis for development of new long-period stacking-ordered magnesium-rare earth alloy, reduce blindness of alloy design, save alloy research and development cost, and improve research and development efficiency.

[0016] (2) The prediction method can accurately and efficiently predict long-period stacking-ordered magnesium-rare earth alloy. BRIEF DESCRIPTION OF DRAWINGS

[0017] The drawings accompanying the specification of the present application form a part thereof, serve to provide further understanding of the present application, and together with the specification explain the present application, and do not constitute improper limitations on the present application.

[0018] Figure 1 It is a flowchart for predicting long-period stacking-ordered magnesium-rare earth alloy of the present application.

[0019] Figure 2 Liquid structure model of pure Mg of the embodiment 1 of the present application;

[0020] Figure 3 Liquid structure model of binary Mg-RE alloy (RE=Y) of the embodiment 1 of the present application;

[0021] Figure 4 Liquid structure model of ternary Mg-RE-X alloy (RE=Y, X=Co, Ni, Cu, Zn, Ag, Cd) of the embodiment 1 of the present application;

[0022] Figure 5 Volume of liquid pure Mg, binary Mg-RE alloy, ternary Mg-RE-X alloy (RE=Y, X=Co, Ni, Cu, Zn, Ag, Cd) of the embodiment 1 of the present application;

[0023] Figure 6 Cohesive energy of liquid pure Mg, binary Mg-RE alloy, ternary Mg-RE-X alloy (RE=Y, X=Co, Ni, Cu, Zn, Ag, Cd) of the embodiment 1 of the present application;

[0024] Figure 7 Chemical short-range order of RE around Mg in liquid ternary Mg-RE-X alloy (RE=Y, X=Co, Ni, Cu, Zn, Ag, Cd) of the embodiment 1 of the present application;

[0025] Figure 8 Chemical short-range order of RE around X in liquid ternary Mg-RE-X alloy (RE=Y, X=Co, Ni, Cu, Zn, Ag, Cd) of the embodiment 1 of the present application;

[0026] Figure 9 Chemical short-range order of X around X in liquid ternary Mg-RE-X alloy (RE=Y, X=Co, Ni, Cu, Zn, Ag, Cd) of the embodiment 1 of the present application;

[0027] Figure 10 Proportion of cubic local symmetry structure in liquid pure Mg, binary Mg-RE alloy, ternary Mg-RE-X alloy (RE=Y, X=Co, Ni, Cu, Zn, Ag, Cd) of the embodiment 1 of the present application;

[0028] Figure 11 Proportion of tetrahedral local symmetry structure in liquid pure Mg, binary Mg-RE alloy, ternary Mg-RE-X alloy (RE=Y, X=Co, Ni, Cu, Zn, Ag, Cd) of the embodiment 1 of the present application;

[0029] Figure 12The proportion of five times local symmetry structure in the liquid pure Mg, binary Mg-RE alloy, ternary Mg-RE-X alloy (RE=Y, X=Co, Ni, Cu, Zn, Ag, Cd) of the embodiment 1 of the application;

[0030] Figure 13 The proportion of six times local symmetry structure in the liquid pure Mg, binary Mg-RE alloy, ternary Mg-RE-X alloy (RE=Y, X=Co, Ni, Cu, Zn, Ag, Cd) of the embodiment 1 of the application;

[0031] Figure 14 The proportion distribution of three times, four times, five times and six times local symmetry structure in the liquid pure Mg, ternary Mg-RE-X alloy (RE=Y, X=Co, Ni, Cu, Zn, Ag, Cd) of the embodiment 1 of the application. DETAILED DESCRIPTION

[0032] It should be noted that the following detailed description is exemplary and is intended to provide further explanation of the application. Unless otherwise indicated, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which the application pertains.

[0033] In the first aspect of the application, a prediction method of long-period stacking ordered magnesium-rare earth alloy is provided, and the specific implementation steps are as follows:

[0034] (1) Model construction

[0035] The liquid structure models of pure Mg, binary Mg-RE alloy and ternary Mg-RE-X alloy and the single atom models of each alloy element are constructed respectively;

[0036] (2) Calculation process

[0037] Through molecular dynamics simulation and first principle calculation, the volume, cohesive energy, chemical short program parameters and proportion of each local structure symmetry of the above models are obtained, and the evolution trend of the volume and cohesive energy of the ternary Mg-RE-X alloy relative to the binary Mg-RE alloy, the chemical short program characteristics and the distribution state of the proportion of each local structure symmetry evolved from the binary Mg-RE alloy and the consistency with pure Mg are analyzed.

[0038] Further, in step (1), the liquid structure models of pure Mg, binary Mg-RE alloy and ternary Mg-RE-X alloy are constructed, so that the atoms are randomly distributed therein, and the model size is adjusted to reach the equilibrium state through molecular dynamics simulation.

[0039] Further, for the single atom model, an orthogonal lattice needs to be constructed, and the lattice parameters meet the following conditions: a≠b≠c. In this model, atoms can be fixed at any position within the lattice.

[0040] Further, in step (2), the calculation parameters are as follows: the simulation temperature needs to be higher than 923K (the melting point of pure Mg), and the total energy convergence criterion of the system is less than or equal to 10 -4 eV / cell; if the NVT ensemble is used, the average pressure on the system should be controlled at 0±5kbar, and if the NPT ensemble is used, the pressure should be set to 0.

[0041] Further, the first-principles calculation is used to implement static self-consistency on the single-atom model to obtain the total energy of each element, and the cohesive energy of each model is calculated according to the following formula:

[0042]

[0043] where E total is the total energy of the model system, N e is the number of elements contained in the model, n i is the number of atoms of each element in the model, and E is the single-atom energy of the element.

[0044] Further, the chemical short-range order analysis can use any chemical short-range order parameters, including the Warren-Cowley chemical short-range order parameters, and the specific calculation formula is as follows.

[0045]

[0046] where c B is the concentration of element B, Z A and Z A-B are the average total coordination number of element A and the average partial coordination number of B around A, respectively.

[0047] Further, through molecular dynamics simulation, the proportion of each local structure symmetry in pure Mg, binary Mg-RE alloy and ternary Mg-RE-X alloy is calculated.

[0048] Further, the analysis method is as follows:

[0049] If the ternary Mg-RE-X alloy cannot have both smaller volume and lower cohesive energy compared with the binary Mg-RE alloy, it is predicted that the long-period stacking ordered phase cannot be formed in the Mg-RE-X alloy; if the ternary Mg-RE-X alloy can have both smaller volume and lower cohesive energy compared with the binary Mg-RE alloy, the chemical short-range order is further analyzed.

[0050] If the chemical short program in the ternary Mg-RE-X alloy fails to show Mg attracting RE, X attracting RE, and X repelling X, it is predicted that the long-period stacking ordered phase cannot be formed in the Mg-RE-X alloy; if the chemical short program in the ternary Mg-RE-X alloy shows Mg attracting RE, X attracting RE, and X repelling X, the evolution trend of the local structure symmetry is further analyzed compared with the binary Mg-RE alloy;

[0051] If the proportion of each local structure symmetry in the ternary Mg-RE-X alloy fails to change to pure Mg compared with the binary Mg-RE alloy, it is predicted that the long-period stacking ordered phase cannot be formed in the Mg-RE-X alloy; if the proportion of each local structure symmetry in the ternary Mg-RE-X alloy changes to pure Mg compared with the binary Mg-RE alloy, the distribution state of the local structure symmetry is further analyzed;

[0052] If the proportional distribution of each local structure symmetry in the ternary Mg-RE-X alloy does not conform to the distribution state in pure Mg, it is predicted that the long-period stacking ordered phase cannot be formed in the Mg-RE-X alloy; if the proportional distribution of each local structure symmetry in the ternary Mg-RE-X alloy is consistent with that in pure Mg, it is finally predicted that the long-period stacking ordered phase can be formed in the Mg-RE-X alloy.

[0053] In the second aspect of the present application, the application of the prediction method of the long-period stacking ordered magnesium rare earth alloy in the field of alloy design is provided.

[0054] In the third aspect of the present application, an alloy design method capable of effectively introducing a long-period stacking ordered phase in a magnesium alloy is provided, which comprises the prediction method of the long-period stacking ordered magnesium rare earth alloy, and a series of long-period stacking ordered Mg-RE-X alloys (RE=Y) including Mg-Y-Co, Mg-Y-Ni, Mg-Y-Cu, Mg-Y-Zn, Mg-Y-Ga, Mg-Y-Ru, Mg-Y-Rh, Mg-Y-Pd, Mg-Y-Ir, Mg-Y-Pt, and Mg-Y-Au alloys are finally predicted according to the method, wherein the Mg-Y-Co, Mg-Y-Ni, Mg-Y-Cu, and Mg-Y-Zn alloys have been verified by experiments.

[0055] In the fourth aspect of the present application, a long-period stacking ordered Mg-RE-X alloy is provided, and the long-period stacking ordered Mg-RE-X alloy comprises Mg-Y-Ga, Mg-Y-Ru, Mg-Y-Rh, Mg-Y-Pd, Mg-Y-Ir, Mg-Y-Pt, and Mg-Y-Au alloys.

[0056] The prediction method flow of the long-period stacking ordered magnesium rare earth alloy based on molecular dynamics simulation and first principle calculation in the present application is as follows Figure 1The liquid structure models of pure Mg, binary Mg-RE alloys, ternary Mg-RE-X alloys and the single atom models of alloying elements are constructed. The volume, cohesive energy, chemical short-range order parameters and the proportion of local structure symmetry of pure Mg, binary Mg-RE alloys and ternary Mg-RE-X alloys are obtained by molecular dynamics simulation and first-principles calculation. By analyzing the evolution trend of volume and cohesive energy of ternary Mg-RE-X alloys relative to binary Mg-RE alloys, the chemical short-range order characteristics and the distribution state of the proportion of local structure symmetry evolved from binary Mg-RE alloys, the consistency with pure Mg is analyzed, and finally the effective prediction of whether long-period stacking ordered phase can be formed in Mg-RE-X alloys is realized.

[0057] The application will be further described in detail below with reference to specific examples, which are intended to explain but not limit the application.

[0058] Example 1

[0059] Taking Mg-Y-Co, Mg-Y-Ni, Mg-Y-Cu, Mg-Y-Zn, Mg-Y-Ag and Mg-Y-Cd as examples, whether different element combinations can introduce long-period stacking ordered phase in magnesium alloy is predicted.

[0060] The liquid structure models of pure Mg, binary Mg-Y alloys and ternary Mg-Y-X alloys (X = Co, Ni, Cu, Zn, Ag, Cd) are constructed as shown in Figures 2-4 .

[0061] Molecular dynamics simulation is performed on the above models, and the single atom energy of Mg, Y, Co, Ni, Cu, Zn, Ag and Cd obtained by first-principles calculation is combined to obtain the volume and cohesive energy as shown in Figure 5 and Figure 6 . The calculation parameters are selected as follows: the simulation temperature is set to 1023 K (about 100 K higher than the melting point of pure Mg), the total energy convergence criterion is less than or equal to 10 -4 eV / cell. The NVT ensemble is used, and the average pressure on the system is controlled at 0±5kbar.

[0062] The Warren-Cowley chemical short-range order parameters α Mg-Y , α X-Y , α X-X in the liquid structure model of ternary Mg-Y-X alloys (X = Co, Ni, Cu, Zn, Ag, Cd) are counted as shown in Figure 7 , 8 , 9.

[0063] The proportions of the cubic, quartic, quintic and sextic local structure symmetries in the liquid structure model of the statistical pure Mg, binary Mg-Y alloy, ternary Mg-Y-X alloy (X = Co, Ni, Cu, Zn, Ag, Cd) were compared with those of the binary Mg-Y alloy and pure Mg, as shown in Figs. Figure 10 , 11 , 12, 13.

[0064] The distribution states of the cubic, quartic, quintic and sextic local structure symmetries in the liquid structure model of the ternary Mg-Y-X alloy (X = Co, Ni, Cu, Zn, Ag, Cd) and pure Mg were compared, as shown in Figs. Figure 14 .

[0065] Figure 5 and Figure 6 It is shown that, except for the Mg-Y-Cd alloy, the Mg-Y-Co, Mg-Y-Ni, Mg-Y-Cu, Mg-Y-Zn and Mg-Y-Ag alloys can have smaller volumes and lower cohesive energies than the binary Mg-Y alloy.

[0066] Figures 7-9 It is shown that, in the Mg-Y-Co, Mg-Y-Ni, Mg-Y-Cu, Mg-Y-Zn, Mg-Y-Ag and Mg-Y-Cd alloys, the Warren-Cowley chemical short-range order parameter exhibits that Mg attracts Y and X (X refers to Co, Ni, Cu, Zn, Ag and Cd) attracts Y and X repels X.

[0067] Figures 10-13 It is shown that, except for the Mg-Y-Cd alloy, the proportions of the cubic, quartic, quintic and sextic local structure symmetries in the Mg-Y-Co, Mg-Y-Ni, Mg-Y-Cu, Mg-Y-Zn and Mg-Y-Ag alloys are converted from the binary Mg-Y alloy to pure Mg.

[0068] Figure 14 It is shown that, except for the Mg-Y-Ag and Mg-Y-Cd alloys, the proportional distribution of the cubic, quartic, quintic and sextic local structure symmetries in the Mg-Y-Co, Mg-Y-Ni, Mg-Y-Cu and Mg-Y-Zn alloys is consistent with the distribution state in pure Mg.

[0069] In combination Figures 5-14 , the Mg-Y-Co, Mg-Y-Ni, Mg-Y-Cu and Mg-Y-Zn alloys are predicted to be long-period stacking-ordered magnesium rare earth alloys.

[0070] The above prediction results can be verified in the following literature records: (S.-B. Mi, et al. Scripta Materialia 68 (2013) 635-638), (K. Ma, et al. Materials Characterization 181 (2021) 111489), (Y. Kawamura, et al. Scripta Materialia 55 (2006) 453-456), (E. Abe, et al. Acta Materialia 50 (2002) 3845-3857).

[0071] The long-period stacking-ordered magnesium-rare earth alloy predicted by the embodiment is consistent with the existing experimental determination results, which indicates that the prediction method has high accuracy.

[0072] Finally, it should be noted that the above only describes the preferred embodiments of the present application and is not intended to limit the present application. Although the present application has been described in detail with reference to the foregoing embodiments, those skilled in the art can still modify the technical solutions described in the foregoing embodiments or make equivalent replacements to some of them. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principles of the present application shall be included in the protection scope of the present application. Although the specific embodiments of the present application have been described above, the description is not intended to limit the protection scope of the present application, and those skilled in the art should understand that various modifications or changes made to the technical solutions of the present application without creative labor are still within the protection scope of the present application.

Claims

1. A method of predicting long period stacking ordered magnesium rare earth alloy, characterized by, The prediction method comprises the following steps: (1) Model construction Respectively construct liquid structure models of pure Mg, binary Mg-RE alloy, ternary Mg-RE-X alloy and single atom models of alloy elements; RE=Y; X=one of Co, Ni, Cu, Zn, Ga, Ru, Rh, Pd, Ir, Pt and Au; (2) Calculation process Through molecular dynamics simulation and first principle calculation, the volume, cohesive energy, chemical short program parameters and proportion of each local structure symmetry of the above models are obtained, the evolution trend of the volume and cohesive energy of the ternary Mg-RE-X alloy relative to the binary Mg-RE alloy, the chemical short program characteristics and the distribution state of the proportion of each local structure symmetry evolved from the binary Mg-RE alloy are analyzed, and the consistency with pure Mg is analyzed. The analysis method is as follows: If the ternary Mg-RE-X alloy cannot have smaller volume and lower cohesive energy compared with the binary Mg-RE alloy, it is predicted that the long-period stacking ordered phase cannot be formed in the Mg-RE-X alloy; if the ternary Mg-RE-X alloy can have smaller volume and lower cohesive energy compared with the binary Mg-RE alloy, the chemical short program is further analyzed; If the chemical short program in the ternary Mg-RE-X alloy cannot show that Mg attracts RE, X attracts RE and X repels X, it is predicted that the long-period stacking ordered phase cannot be formed in the Mg-RE-X alloy; if the chemical short program of the ternary Mg-RE-X alloy shows that Mg attracts RE, X attracts RE and X repels X, the evolution trend of the proportion of each local structure symmetry compared with the binary Mg-RE alloy is further analyzed; If the proportion of each local structure symmetry in the ternary Mg-RE-X alloy cannot be converted to pure Mg compared with the binary Mg-RE alloy, it is predicted that the long-period stacking ordered phase cannot be formed in the Mg-RE-X alloy; if the proportion of each local structure symmetry in the ternary Mg-RE-X alloy is converted to pure Mg compared with the binary Mg-RE alloy, the distribution state of the local structure symmetry is further analyzed; If the proportion distribution of each local structure symmetry in the ternary Mg-RE-X alloy does not conform to the distribution state in pure Mg, it is predicted that the long-period stacking ordered phase cannot be formed in the Mg-RE-X alloy; if the proportion distribution of each local structure symmetry in the ternary Mg-RE-X alloy is consistent with that in pure Mg, it is finally predicted that the long-period stacking ordered phase can be formed in the Mg-RE-X alloy.

2. The prediction method of claim 1, wherein, In step (1), the liquid structure models of pure Mg, binary Mg-RE alloy and ternary Mg-RE-X alloy are constructed, and atoms are randomly distributed therein, and the model size is adjusted to reach the equilibrium state through molecular dynamics simulation.

3. The prediction method of claim 1, wherein For the single atom model, an orthogonal lattice is constructed, and the lattice parameters meet the following conditions: a≥10 Å, b≥10 Å, c≥10 Å, a≠b≠c; in the model, atoms can be fixed at any position in the lattice.

4. The prediction method of claim 1, wherein In step (2), the calculation parameters are as follows: the simulation temperature needs to be higher than 923 K (the melting point of pure Mg), and the total energy convergence criterion is less than or equal to 10 -4 eV / cell; if the NVT ensemble is used, the average pressure on the system should be controlled at 0±5 kbar, and if the NPT ensemble is used, the pressure should be set to 0.

5. The method of claim 1, wherein, The single atom model is implemented static self-consistent by using first principle calculation, the total energy of each element is obtained, and the cohesive energy of each model is calculated according to the following formula; wherein, is the total energy of the model system, is the number of elements included in the model, is the number of atoms of each element in the model, is the monatomic energy of the element.

6. The prediction method of claim 1, wherein Chemical short-range order analysis uses any chemical short-range order parameter, Or, by molecular dynamics simulation, the proportion of each local structure symmetry in pure Mg, binary Mg-RE alloy and ternary Mg-RE-X alloy is calculated.

7. The prediction method of claim 6, wherein, The Warren-Cowley chemical short-range order parameter is used, and the specific calculation formula is as follows: wherein is the concentration of element B, and are the average total coordination number of element A and the average partial coordination number of B around A, respectively.

8. The application of the prediction method of long-period stacking-ordered magnesium rare earth alloy according to any one of claims 1-7 in the field of alloy design.

9. A method of alloy design effective to introduce a long period stacking ordered phase in a magnesium alloy, characterized by, The alloy design method comprises the prediction method of long-period stacking-ordered magnesium rare earth alloy according to any one of claims 1-7.

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