Method for calculating and optimizing spray-formed ultrahigh-strength 7-series aluminum alloy components through thermodynamics

Abstract

The invention relates to a method for optimizing spray-formed ultrahigh-strength 7-series aluminum alloy components, in particular to a method for optimizing spray-formed ultrahigh-strength 7-series aluminum alloy components through thermodynamic calculation. The problem that components of the spray-formed ultrahigh-strength aluminum alloy are difficult to optimize is solved. According to the method, the mechanical property parameters of the common second phase in the alloy can be obtained by carrying out first principle calculation on the common second phase, and screening of the strengthening phase with the highest comprehensive performance is facilitated. The calculation of the non-equilibrium solidification process of alloys with different components is used for predicting the influence rule of the non-equilibrium solidification process of spray forming on the alloy solidification structure, the calculation of the alloy phase diagram can optimize the content of each alloy element, then the optimization of the alloy components is guided, and high-efficiency and low-cost optimization is carried out on the components of the spray forming ultrahigh-strength aluminum alloy. And an efficient and cheap way is provided for optimization of the spray-formed ultrahigh-strength aluminum alloy, and application of the spray-formed ultrahigh-strength aluminum alloy to major engineering structural parts is facilitated.

Description

Technical Field

[0001] The invention relates to a method for optimizing the composition of a spray-formed ultra-high-strength aluminum alloy by utilizing thermodynamic calculation. Background Art

[0002] High-performance, large-size aluminum alloy load-bearing components are the core components of equipment in the fields of aviation, aerospace and rail transportation. Large-size aircraft extrusion wide thin walls (structural length greater than 10m (width greater than 400mm)) and new generation aerospace cones (outer diameter greater than 1000mm) are the current development priorities of my country's aerospace industry, and urgent demands are placed on large-size, high-performance aluminum alloy ingots and processing. At present, high-strength aluminum alloys are mainly prepared by traditional semi-continuous casting, but due to the problem of consistency of organizational properties caused by high alloying and non-uniform solidification conditions, conventional melting and casting has been difficult to break through the preparation of high-strength and toughness and large-size ingots. Conventional melting and casting are prone to obvious macrosegregation, coarse dendrites, cracking and other problems, resulting in unstable ingot quality, difficult processing and low yield. In order to meet the urgent needs of large-size, high-performance core components in the fields of aviation, aerospace and rail transportation, it is necessary to further carry out research on key technologies for the preparation of large-size spray-formed ultra-high-strength aluminum alloys, focusing on breakthroughs in the preparation of large-size, high-metallurgical quality spray-formed aluminum alloy ingots and key technologies for hot processing and deformation heat treatment of large-size ultra-high-strength aluminum alloys.

[0003] The solidification structure of ultra-high-strength aluminum alloy directly determines the subsequent processing performance of the material and even the final mechanical properties of the parts. Therefore, it is very important to control the composition, morphology, distribution, etc. of the second phase. Appropriate alloy composition and optimized spray forming cooling and solidification conditions are the key to determining the solidification structure and second phase state of the material. Spray forming is a typical non-equilibrium solidification process. Its alloying element distribution, solidification structure, and precipitation phase structure are very different from traditional solidification processes. Traditional composition design theory and phase structure screening methods are not suitable for spray forming alloy systems. Therefore, in order to break through the key technology of composition design of ultra-high-strength aluminum alloys in spray forming, it is necessary to solve the key scientific problem of "the correlation mechanism between the composition and phase structure and solidification structure of ultra-high-strength aluminum alloys under large-scale spray forming conditions", and use the obtained main alloy and micro-alloying elements under rapid solidification conditions. The law of action and phase screening theory on the solidification structure and second phase structure guide the composition design work.

[0004] Therefore, in response to the demand for high-performance lightweight materials in the fields of aerospace, transportation, etc., the development of key technologies for rapid non-equilibrium solidification aluminum alloy composition design based on spray forming and processing, forming and heat treatment suitable for spray-formed alloys is of great significance to promote the application of spray-formed ultra-high strength aluminum alloys in major engineering structural parts. Summary of the invention

[0005] In order to solve the problem of difficult optimization of the composition of spray-formed ultra-high-strength aluminum alloy, the present invention proposes a method for optimizing the composition of spray-formed ultra-high-strength aluminum alloy using thermodynamic calculation. The thermodynamic calculation can predict the influence of the non-equilibrium solidification process on the second phase content of the alloy, and obtain the influence of the proportion of different elements on the change of the second phase fraction in the alloy, thereby guiding the optimization of the alloy composition and optimizing the composition of the spray-formed ultra-high-strength aluminum alloy with high efficiency and low cost. The method of designing the composition of the spray-formed ultra-high-strength aluminum alloy using thermodynamic calculation of the present invention is carried out according to the following steps:

[0006] The method of optimizing the composition of the spray-formed ultra-high strength 7 series aluminum alloy by thermodynamic calculation is carried out in the following steps:

[0007] Step 1: Import the second phase unit cell model: Use FindIt software to find the unit cell model of the second phase in the alloy, and import the unit cell model of the second phase into the first principle calculation software MaterialsStudio;

[0008] Step 2: Geometry optimization: Use the GeometryOptimization task in the CASTEP module of MaterialsStudio to optimize the geometry of the unit cell model of the second phase; use the PBE functional in the generalized gradient approximation method to calculate the correlation energy in the geometry optimization; set the quality to the best; set the cutoff energy, convergence accuracy, pseudopotential and k-point to perform the first structure optimization; after the first structure optimization, compare and record the volume deviation of the unit cell before and after the calculation; reset the cutoff energy, increase the k-point, keep the convergence accuracy and pseudopotential unchanged, and perform structure optimization again; after performing the structure optimization again, compare and record the volume deviation of the unit cell before and after the calculation, and repeat the optimization until the volume deviation of the unit cell is minimized;

[0009] The cutoff energy for the first geometry optimization in step 2 is set to 400 eV, and the cutoff energy for each subsequent geometry optimization is increased by 50 eV; the convergence accuracy of the first geometry optimization is set to SCFtolerance 5e-7; the pseudopotential for the first geometry optimization is an ultrasoft pseudopotential; the k-point is composed of the unit cell constants a, b and c of the second phase, and the actual spacing between a, b and c in the first geometry optimization is less than 0.001;

[0010] Step 3. Calculation of unit cell energy: Use the Energy task in the CASTEP module of MaterialsStudio to perform energy calculation on the second-phase unit cell model after structural optimization in step 2. The cutoff energy, convergence accuracy, pseudopotential and k-point used in the energy calculation are consistent with the minimum volume deviation value of the unit cell after geometric structure optimization in step 2. After the energy calculation, record the number of elements in the unit cell and the final energy.

[0011] Step 4. Calculation of unit cell elastic constants: Use the ElasticConstants task in the CASTEP module of MaterialsStudio to calculate the elastic constants of the second-phase unit cell model after the structural optimization in step 2. The number of stresses in each step of the calculation is set to 6, and the cutoff energy, convergence accuracy, pseudopotential, and k-point are consistent with the minimum volume deviation value of the unit cell after the geometric structure optimization in step 2.

[0012] Step 5. Calculation of mechanical properties of each phase of the unit cell: Analyze the file calculated in step 4 through the Analysis task in the CASTEP module of MaterialsStudio, and calculate the bulk modulus, shear modulus, Young's modulus and Poisson's ratio of the unit cell using elastic constants;

[0013] Step 6. Establish the single atomic structure of each element in the alloy: Use Materials Studio to build a model of a single atom, select 3D Atomistic in new Document, establish a 3D atomic model, use the Build module to create a cubic empty package without atoms, use the AddAtoms module to add atoms to the cubic empty package, and set the position of the atom to the center of the cube;

[0014] In step 6, the side length of the cubic empty bag is a: b: c: The space group is P1; the atoms added to the cubic empty package using the AddAtoms module are Al, Zn, Mg, Cu, Zr, and Sc; the atomic positions are a: 0.5, b: 0.5, c: 0.5, and the atomic position is the center of the cube;

[0015] Step 7. Calculation of single atom energy: Calculate the energy of a single atom through the Energy task in the CASTEP module of MaterialsStudio. Select Ultra-fine for Quality. The calculation method of correlation energy uses the PBE functional in the generalized gradient approximation method. The pseudopotential is set to ultrasoft pseudopotential, the k-point is set to Gammapointonly, the spin is turned on, the Metal option is unchecked, and the apparent spin is used as the initial spin.

[0016] Step 8. Importing the unit cell model of the element: Use the FindIt software to find the unit cell model of each element in the alloy, and import it into the first principle calculation software MaterialsStudio;

[0017] Step 9: Establish the supercell structure of the element single-substance model: Use the Supercell module of MaterialsStudio to establish a single-substance supercell and set the supercell range;

[0018] Step 10. Optimize the geometric structure of the single-element unit cell model: Optimize the geometric structure of the single-element unit cell model through the Geometry Optimization task in the CASTEP module of Materials Studio. The calculation method of the correlation energy uses the PBE functional in the generalized gradient approximation method; set the cutoff energy, convergence accuracy, pseudopotential and k-point to perform the first geometric structure optimization; after the first geometric structure optimization, compare and record the volume deviation of the unit cell before and after the calculation; reset the cutoff energy, increase the k-point, keep the convergence accuracy and pseudopotential unchanged, and perform structural optimization again; after performing structural optimization again, compare and record the volume deviation of the unit cell before and after the calculation, and repeat the optimization until the volume deviation of the unit cell is minimized;

[0019] The cutoff energy of the first geometry optimization in step 10 is set to 100 eV, and the cutoff energy is increased by 50 eV each time the geometry optimization is performed thereafter; the convergence accuracy of the first geometry optimization is set to SCFtolerance 5e-7; the pseudopotential of the first geometry optimization is an ultrasoft pseudopotential; the k-point is composed of the unit cell constants a, b and c of the second phase, and the actual spacing in the a, b and c directions of the first geometry optimization is less than 0.001;

[0020] Step 11. Energy calculation of single-element unit cell model: Use the Energy task in the CASTEP module of MaterialsStudio to perform energy calculation on the single-element unit cell model after structural optimization in step 10. The cutoff energy, convergence accuracy, pseudopotential, and k-point used in the energy calculation are consistent with the minimum volume deviation value of the unit cell after geometric structure optimization in step 10. The final calculated energy is divided by the number of atoms in the supercell to obtain the energy of a single atom when it constitutes a single substance.

[0021] Step 12: Calculation of the binding energy and formation enthalpy of the second phase: Using the unit cell energy obtained in step 3 and the single atom energy obtained in step 7, the binding energy and formation enthalpy of each second phase are calculated by corresponding formulas;

[0022] Step 13. Calculation of alloy equilibrium solidification process: Use the oneaxisequilibrium module in termo-calc software to calculate the composition of the 7 series aluminum alloy to be optimized: select the Al alloy database, select Al, Zn, Mg, Cu, Zr, Sc as the calculation objects, specify the system pressure and system size for calculation, specify the element composition unit as mass fraction, set the element composition, the calculation type as uniaxial calculation, the x-axis variable as temperature, specify the calculation range and step size, and perform the calculation;

[0023] In step 13, the system pressure is 101325Pa; the calculated system size is 1 mol; the element composition is Zn: 11.3wt%, Mg: 2.45wt%, Cu: 1.5wt%, Zr: 0.15wt%, Sc: 0.15wt%, Al: Bal.; the calculation range is 0℃-900℃; the step length is 10℃;

[0024] Step 14. Calculation of alloy non-equilibrium solidification process: Use the Scheil Solidification module in the termo-calc software, select the Al alloy database, select Al, Zn, Mg, Cu, Zr, and Sc as the calculation objects, specify the initial calculation temperature and calculation step, specify the element composition unit as mass fraction, set the element composition, and use the classic Scheil model as the calculation model to perform the calculation;

[0025] Step 15. Calculate the alloy phase diagram: Use the phasediagram module in termo-calc software, select the Al alloy database, select Al, Zn, Mg, Cu, Zr, and Sc as the calculation objects, specify the calculation system pressure and system size, the calculation type is phase diagram calculation, specify the x-axis variable as the element mass fraction, the y-axis as the temperature, adjust the calculation step size and the element calculation range, perform the first calculation, after the calculation is completed, change the element type, calculate again, and repeat the calculation process until all elements are calculated;

[0026] In step fifteen, the system pressure is 101325Pa; the system size is 1 mol; the temperature calculation range is 0℃-900℃; the calculation step is 10℃; Zn, Mg, Cu, the calculation range of Zn element is 6wt%-16wt%, the calculation range of Mg element is 0wt%-10wt%, the calculation range of Cu element is 0wt%-10wt%, and the x-axis calculation step is 0.5wt%.

[0027] The principles and beneficial effects of the present invention are:

[0028] The present invention optimizes the composition of the spray-formed ultra-high-strength 7-series aluminum alloy using first-principles calculation and thermodynamic calculation methods, which greatly improves the efficiency of alloy composition optimization and reduces the optimization cost. By performing first-principles calculations on common second phases, the mechanical property parameters of common second phases in the alloy can be obtained, which helps to screen out the strengthening phase with the highest comprehensive performance. By calculating the non-equilibrium solidification process of alloys with different components, it can be used to predict the influence of the spray-formed non-equilibrium solidification process on the solidification structure of the alloy. By calculating the alloy phase diagram, the content of each alloying element can be optimized. It provides an efficient and inexpensive way to optimize the spray-formed ultra-high-strength aluminum alloy, which helps to apply the spray-formed ultra-high-strength aluminum alloy in major engineering structural parts. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] Figure 1 This is a unit cell model diagram of the second phase in step 1 of Example 1;

[0030] Figure 2 The single atom model in step 6 of Example 1;

[0031] Figure 3 The single substance model in step nine of Example 1;

[0032] Figure 4 This is a diagram of the alloy equilibrium solidification process in step 13 of Example 1;

[0033] Figure 5 This is a diagram of the non-equilibrium solidification process of the alloy in step 14 of Example 1;

[0034] Figure 6 The Al-11.3Zn-1.5Cu-0.15Zr-0.15Sc-xMg alloy phase diagram calculated in step 15 of Example 1;

[0035] Figure 7 The Al-11.3Zn-2.45Mg-0.15Zr-0.15Sc-xCu alloy phase diagram calculated in step 15 of Example 1;

[0036] Figure 8 The Al-2.45Mg-1.5Cu-0.15Zr-0.15Sc-xZn alloy phase diagram calculated in step 15 of Example 1;

[0037] Fig. 9 The Al-11.3Zn-1.5Cu-xMg alloy phase diagram calculated in step 15 of Example 1;

[0038] Fig.10 The Al-11.3Zn-2.45Mg-xCu alloy phase diagram calculated in step 15 of Example 1;

[0039] Fig.11 This is the Al-2.45Mg-1.5Cu-xZn alloy phase diagram calculated in step 15 of Example 1. DETAILED DESCRIPTION

[0040] The technical solution of the present invention is not limited to the specific implementation modes listed below, but also includes any reasonable combination of the specific implementation modes.

[0041] Specific implementation method 1: This implementation method uses thermodynamic calculation to optimize the composition of the spray-formed ultra-high strength 7-series aluminum alloy according to the following steps:

[0042] Step 1: Import the second phase unit cell model: Use FindIt software to find the unit cell model of the second phase in the alloy, and import the unit cell model of the second phase into the first principle calculation software MaterialsStudio;

[0043] Step 2: Geometry optimization: Use the GeometryOptimization task in the CASTEP module of MaterialsStudio to optimize the geometry of the unit cell model of the second phase; use the PBE functional in the generalized gradient approximation method to calculate the correlation energy in the geometry optimization; set the quality to the best; set the cutoff energy, convergence accuracy, pseudopotential and k-point to perform the first structure optimization; after the first structure optimization, compare and record the volume deviation of the unit cell before and after the calculation; reset the cutoff energy, increase the k-point, keep the convergence accuracy and pseudopotential unchanged, and perform structure optimization again; after performing the structure optimization again, compare and record the volume deviation of the unit cell before and after the calculation, and repeat the optimization until the volume deviation of the unit cell is minimized;

[0044] The cutoff energy for the first geometry optimization in step 2 is set to 400 eV, and the cutoff energy for each subsequent geometry optimization is increased by 50 eV; the convergence accuracy of the first geometry optimization is set to SCFtolerance 5e-7; the pseudopotential for the first geometry optimization is an ultrasoft pseudopotential; the k-point is composed of the unit cell constants a, b and c of the second phase, and the actual spacing between a, b and c in the first geometry optimization is less than 0.001;

[0045] Step 3. Calculation of unit cell energy: Use the Energy task in the CASTEP module of MaterialsStudio to perform energy calculation on the second-phase unit cell model after structural optimization in step 2. The cutoff energy, convergence accuracy, pseudopotential and k-point used in the energy calculation are consistent with the minimum volume deviation value of the unit cell after geometric structure optimization in step 2. After the energy calculation, record the number of elements in the unit cell and the final energy.

[0046] Step 4. Calculation of unit cell elastic constants: Use the ElasticConstants task in the CASTEP module of MaterialsStudio to calculate the elastic constants of the second-phase unit cell model after the structural optimization in step 2. The number of stresses in each step of the calculation is set to 6, and the cutoff energy, convergence accuracy, pseudopotential, and k-point are consistent with the minimum volume deviation value of the unit cell after the geometric structure optimization in step 2.

[0047] Step 5. Calculation of mechanical properties of each phase of the unit cell: Analyze the file calculated in step 4 through the Analysis task in the CASTEP module of MaterialsStudio, and calculate the bulk modulus, shear modulus, Young's modulus and Poisson's ratio of the unit cell using elastic constants;

[0048] Step 6. Establish the single atomic structure of each element in the alloy: Use Materials Studio to build a model of a single atom, select 3D Atomistic in new Document, establish a 3D atomic model, use the Build module to create a cubic empty package without atoms, use the AddAtoms module to add atoms to the cubic empty package, and set the position of the atom to the center of the cube;

[0049] In step 6, the side length of the cubic empty bag is a: b: c: The space group is P1; the atoms added to the cubic empty package using the AddAtoms module are Al, Zn, Mg, Cu, Zr, and Sc; the atomic positions are a: 0.5, b: 0.5, c: 0.5, and the atomic position is the center of the cube;

[0050] Step 7. Calculation of single atom energy: Calculate the energy of a single atom through the Energy task in the CASTEP module of MaterialsStudio. Select Ultra-fine for Quality. The calculation method of correlation energy uses the PBE functional in the generalized gradient approximation method. The pseudopotential is set to ultrasoft pseudopotential, the k-point is set to Gammapointonly, the spin is turned on, the Metal option is unchecked, and the apparent spin is used as the initial spin.

[0051] Step 8. Importing the unit cell model of the element: Use the FindIt software to find the unit cell model of each element in the alloy, and import it into the first principle calculation software MaterialsStudio;

[0052] Step 9: Establish the supercell structure of the element single-substance model: Use the Supercell module of MaterialsStudio to establish a single-substance supercell and set the supercell range;

[0053] Step 10. Optimize the geometric structure of the single-element unit cell model: Optimize the geometric structure of the single-element unit cell model through the Geometry Optimization task in the CASTEP module of Materials Studio. The calculation method of the correlation energy uses the PBE functional in the generalized gradient approximation method; set the cutoff energy, convergence accuracy, pseudopotential and k-point to perform the first geometric structure optimization; after the first geometric structure optimization, compare and record the volume deviation of the unit cell before and after the calculation; reset the cutoff energy, increase the k-point, keep the convergence accuracy and pseudopotential unchanged, and perform structural optimization again; after performing structural optimization again, compare and record the volume deviation of the unit cell before and after the calculation, and repeat the optimization until the volume deviation of the unit cell is minimized;

[0054] The cutoff energy of the first geometry optimization in step 10 is set to 100 eV, and the cutoff energy is increased by 50 eV each time the geometry optimization is performed thereafter; the convergence accuracy of the first geometry optimization is set to SCFtolerance 5e-7; the pseudopotential of the first geometry optimization is an ultrasoft pseudopotential; the k-point is composed of the unit cell constants a, b and c of the second phase, and the actual spacing in the a, b and c directions of the first geometry optimization is less than 0.001;

[0055] Step 11. Energy calculation of single-element unit cell model: Use the Energy task in the CASTEP module of MaterialsStudio to perform energy calculation on the single-element unit cell model after structural optimization in step 10. The cutoff energy, convergence accuracy, pseudopotential, and k-point used in the energy calculation are consistent with the minimum volume deviation value of the unit cell after geometric structure optimization in step 10. The final calculated energy is divided by the number of atoms in the supercell to obtain the energy of a single atom when it constitutes a single substance.

[0056] Step 12: Calculation of the binding energy and formation enthalpy of the second phase: Using the unit cell energy obtained in step 3 and the single atom energy obtained in step 7, the binding energy and formation enthalpy of each second phase are calculated by corresponding formulas;

[0057] Step 13. Calculation of alloy equilibrium solidification process: Use the oneaxisequilibrium module in termo-calc software to calculate the composition of the 7 series aluminum alloy to be optimized: select the Al alloy database, select Al, Zn, Mg, Cu, Zr, Sc as the calculation objects, specify the system pressure and system size for calculation, specify the element composition unit as mass fraction, set the element composition, the calculation type as uniaxial calculation, the x-axis variable as temperature, specify the calculation range and step size, and perform the calculation;

[0058] In step 13, the system pressure is 101325Pa; the calculated system size is 1 mol; the element composition is Zn: 11.3wt%, Mg: 2.45wt%, Cu: 1.5wt%, Zr: 0.15wt%, Sc: 0.15wt%, Al: Bal.; the calculation range is 0℃-900℃; the step length is 10℃;

[0059] Step 14. Calculation of alloy non-equilibrium solidification process: Use the Scheil Solidification module in the termo-calc software, select the Al alloy database, select Al, Zn, Mg, Cu, Zr, and Sc as the calculation objects, specify the initial calculation temperature and calculation step, specify the element composition unit as mass fraction, set the element composition, and use the classic Scheil model as the calculation model to perform the calculation;

[0060] Step 15. Calculate the alloy phase diagram: Use the phasediagram module in termo-calc software, select the Al alloy database, select Al, Zn, Mg, Cu, Zr, and Sc as the calculation objects, specify the calculation system pressure and system size, the calculation type is phase diagram calculation, specify the x-axis variable as the element mass fraction, the y-axis as the temperature, adjust the calculation step size and the element calculation range, perform the first calculation, after the calculation is completed, change the element type, calculate again, and repeat the calculation process until all elements are calculated;

[0061] In step fifteen, the system pressure is 101325Pa; the system size is 1 mol; the temperature calculation range is 0℃-900℃; the calculation step is 10℃; Zn, Mg, Cu, the calculation range of Zn element is 6wt%-16wt%, the calculation range of Mg element is 0wt%-10wt%, the calculation range of Cu element is 0wt%-10wt%, and the x-axis calculation step is 0.5wt%.

[0062] This implementation has the following beneficial effects:

[0063] This embodiment uses first principle calculation and thermodynamic calculation methods to optimize the composition of the spray-formed ultra-high strength 7 series aluminum alloy, which greatly improves the efficiency of alloy composition optimization and reduces the optimization cost. By performing first principle calculations on common second phases, the mechanical property parameters of common second phases in the alloy can be obtained, which helps to screen out the strengthening phase with the highest comprehensive performance. By calculating the non-equilibrium solidification process of alloys with different compositions, it can be used to predict the influence of the spray-formed non-equilibrium solidification process on the solidification structure of the alloy. By calculating the alloy phase diagram, the content of each alloying element can be optimized. It provides an efficient and inexpensive way to optimize spray-formed ultra-high strength aluminum alloys, which helps to apply spray-formed ultra-high strength aluminum alloys in major engineering structures.

[0064] Specific implementation method 2: The difference between this implementation method and specific implementation method 1 is that the alloy described in step 1 is a 7 series aluminum alloy.

[0065] Specific embodiment 3: This embodiment is different from specific embodiment 1 or 2 in that the second phase in step 1 includes Al2CuMg, Al2Cu, MgZn2, Mg2Zn 11 , Al3Sc and Al3Zr.

[0066] Specific implementation method four: This implementation method is different from any one of specific implementation methods one to three in that: the process of increasing the k-point described in step two is: first increase the value of a by 1, and select the values ​​of b and c from 1 to 8. If the actual spacing of a, b, and c after adjustment is less than 0.001, stop adjusting for structural optimization; if the actual spacing of a, b, and c after adjustment is greater than 0.001, then increase the value of a by 1 again, and select the values ​​of b and c from 1 to 8, until the actual spacing of a, b, and c is less than 0.001.

[0067] Specific implementation mode 5: This implementation mode is different from any one of specific implementation modes 1 to 4 in that the single element in step 8 includes Al, Zn, Mg, Cu, Zr and Sc.

[0068] Specific implementation method six: This implementation method is different from any one of specific implementation methods one to five in that: in step nine, the supercell range is set to: A: 2, the a-axis direction of the unit cell is expanded by 2 times; B: 2, the b-axis direction of the unit cell is expanded by 2 times; C: 2, the c-axis direction of the unit cell is expanded by 2 times.

[0069] Specific implementation method seven: The difference between this implementation method and any one of specific implementation methods one to six is ​​that the process of improving k-point described in step ten is: first increase the value of a by 1, and select the values ​​of b and c from 1 to 8. If the actual spacing of a, b, and c after adjustment is less than 0.001, stop adjusting for structural optimization; if the actual spacing of a, b, and c after adjustment is greater than 0.001, then increase the value of a by 1 again, and select the values ​​of b and c from 1 to 8, until the actual spacing of a, b, and c is less than 0.001.

[0070] Specific implementation eight: This implementation differs from one of the specific implementations one to seven in that the calculation formula for the binding energy in step twelve is:

[0071]

[0072] In formula 1: E coh is the binding energy, in eV·atom -1 ; is the total energy of the crystal, in eV·atom -1 ; and is the energy of a single free-state atom of A, B, or C, in eV·atom -1 ; N A 、N B and N C is the number of A, B, and C atoms in the primitive cell.

[0073] Specific embodiment 9: This embodiment differs from any one of specific embodiments 1 to 8 in that: the calculation formula for the formation enthalpy in step 12 is:

[0074]

[0075] In formula 2: ΔH is the binding energy, the unit is eV·atom -1 , where: is the total energy of the crystal, in eV·atom -1 ; and is the average energy of each atom in the single substances A, B, and C, in units of eV·atom -1 ; N A 、N B and N C is the number of A, B, and C atoms in the primitive cell.

[0076] Specific implementation ten: This implementation differs from any one of specific implementations one to nine in that: in step fourteen, the initial calculation temperature is 900°C, and the calculation step is 10°C; the element composition is Zn: 11.3wt%, Mg: 2.45wt%, Cu: 1.5wt%, Zr: 0.15wt%, Sc: 0.15wt%, Al: Bal.

[0077] Embodiment 1:

[0078] The method of optimizing the composition of the spray-formed ultra-high strength 7-series aluminum alloy by thermodynamic calculation in this embodiment is carried out in the following steps:

[0079] Step 1: Import the second phase unit cell model: Use FindIt software to find the unit cell model of the second phase in the alloy, and import the unit cell model of the second phase into the first principle calculation software MaterialsStudio;

[0080] The alloy described in step 1 is 7 series aluminum alloy;

[0081] The second phase in step 1 includes Al2CuMg, Al2Cu, MgZn2, Mg2Zn 11 , Al3Sc, Al3Zr;

[0082] Step 2: Geometry optimization: Use the GeometryOptimization task in the CASTEP module of MaterialsStudio to optimize the geometry of the unit cell model of the second phase; use the PBE functional in the generalized gradient approximation method to calculate the correlation energy in the geometry optimization; set the quality to the best; set the cutoff energy, convergence accuracy, pseudopotential and k-point to perform the first structure optimization; after the first structure optimization, compare and record the volume deviation of the unit cell before and after the calculation; reset the cutoff energy, increase the k-point, keep the convergence accuracy and pseudopotential unchanged, and perform structure optimization again; after performing the structure optimization again, compare and record the volume deviation of the unit cell before and after the calculation, and repeat the optimization until the volume deviation of the unit cell is minimized;

[0083] The process of improving k-point in step 2 is as follows: first, the value of a is increased by 1, and the values ​​of b and c are selected from 1 to 8. If the actual spacing of a, b, and c after adjustment is less than 0.001, the adjustment is stopped for structural optimization; if the actual spacing of a, b, and c after adjustment is greater than 0.001, the value of a is increased by 1 again, and the values ​​of b and c are selected from 1 to 8 until the actual spacing of a, b, and c is less than 0.001;

[0084] The cutoff energy for the first geometry optimization in step 2 is set to 400 eV, and the cutoff energy for each subsequent geometry optimization is increased by 50 eV; the convergence accuracy of the first geometry optimization is set to SCFtolerance 5e-7; the pseudopotential for the first geometry optimization is an ultrasoft pseudopotential; the k-point is composed of the unit cell constants a, b and c of the second phase, and the actual spacing between a, b and c in the first geometry optimization is less than 0.001;

[0085] Step 3. Calculation of unit cell energy: Use the Energy task in the CASTEP module of MaterialsStudio to perform energy calculation on the second-phase unit cell model after structural optimization in step 2. The cutoff energy, convergence accuracy, pseudopotential and k-point used in the energy calculation are consistent with the minimum volume deviation value of the unit cell after geometric structure optimization in step 2. After the energy calculation, record the number of elements in the unit cell and the final energy.

[0086] Step 4. Calculation of unit cell elastic constants: Use the ElasticConstants task in the CASTEP module of MaterialsStudio to calculate the elastic constants of the second-phase unit cell model after the structural optimization in step 2. The number of stresses in each step of the calculation is set to 6, and the cutoff energy, convergence accuracy, pseudopotential, and k-point are consistent with the minimum volume deviation value of the unit cell after the geometric structure optimization in step 2.

[0087] Step 5. Calculation of mechanical properties of each phase of the unit cell: Analyze the file calculated in step 4 through the Analysis task in the CASTEP module of MaterialsStudio, and calculate the bulk modulus, shear modulus, Young's modulus and Poisson's ratio of the unit cell using elastic constants;

[0088] In this step, the mechanical property parameters of the common second phases in the alloy can be obtained by performing first principle calculations on the common second phases; Table 1 shows the mechanical properties of the second phases calculated in step 5 of Example 1; the compression resistance, shear resistance, stiffness, and plasticity of each second phase can be determined by Table 1. It can be seen from Table 1 that the phase with the best comprehensive performance is the Al2Cu phase, the phase with the best toughness is the MgZn2 phase, and the phase with the best strength is the Al3Sc phase.

[0089] Table 1

[0090]

[0091] Step 6. Establish the single atomic structure of each element in the alloy: Use Materials Studio to build a model of a single atom, select 3D Atomistic in new Document, establish a 3D atomic model, use the Build module to create a cubic empty package without atoms, use the AddAtoms module to add atoms to the cubic empty package, and set the position of the atom to the center of the cube;

[0092] In step 6, the side length of the cubic empty bag is a: b: c: The space group is P1; the atoms added to the cubic empty package using the AddAtoms module are Al, Zn, Mg, Cu, Zr, and Sc; the atomic positions are a: 0.5, b: 0.5, c: 0.5, and the atomic position is the center of the cube;

[0093] Step 7. Calculation of single atom energy: Calculate the energy of a single atom through the Energy task in the CASTEP module of MaterialsStudio. Select Ultra-fine for Quality. The calculation method of correlation energy uses the PBE functional in the generalized gradient approximation method. The pseudopotential is set to ultrasoft pseudopotential, the k-point is set to Gammapointonly, the spin is turned on, the Metal option is unchecked, and the apparent spin is used as the initial spin.

[0094] Step 8. Importing the unit cell model of the element: Use the FindIt software to find the unit cell model of each element in the alloy, and import it into the first principle calculation software MaterialsStudio;

[0095] The elemental substances in step eight include Al, Zn, Mg, Cu, Zr, and Sc;

[0096] Step 9: Establish the supercell structure of the element single-substance model: Use the Supercell module of MaterialsStudio to establish a single-substance supercell and set the supercell range;

[0097] In step nine, the supercell range is set as follows: A: 2, the a-axis direction of the unit cell is expanded by 2 times; B: 2, the b-axis direction of the unit cell is expanded by 2 times; C: 2, the c-axis direction of the unit cell is expanded by 2 times;

[0098] Step 10. Optimize the geometric structure of the single-element unit cell model: Optimize the geometric structure of the single-element unit cell model through the Geometry Optimization task in the CASTEP module of Materials Studio. The calculation method of the correlation energy uses the PBE functional in the generalized gradient approximation method; set the cutoff energy, convergence accuracy, pseudopotential and k-point to perform the first geometric structure optimization; after the first geometric structure optimization, compare and record the volume deviation of the unit cell before and after the calculation; reset the cutoff energy, increase the k-point, keep the convergence accuracy and pseudopotential unchanged, and perform structural optimization again; after performing structural optimization again, compare and record the volume deviation of the unit cell before and after the calculation, and repeat the optimization until the volume deviation of the unit cell is minimized;

[0099] The process of improving k-point in step 10 is as follows: first, the value of a is increased by 1, and the values ​​of b and c are selected from 1 to 8. If the actual spacing of a, b, and c after adjustment is less than 0.001, the adjustment is stopped for structural optimization; if the actual spacing of a, b, and c after adjustment is greater than 0.001, the value of a is increased by 1 again, and the values ​​of b and c are selected from 1 to 8, until the actual spacing of a, b, and c is less than 0.001;

[0100] The cutoff energy of the first geometry optimization in step 10 is set to 100 eV, and the cutoff energy is increased by 50 eV each time the geometry optimization is performed thereafter; the convergence accuracy of the first geometry optimization is set to SCFtolerance 5e-7; the pseudopotential of the first geometry optimization is an ultrasoft pseudopotential; the k-point is composed of the unit cell constants a, b and c of the second phase, and the actual spacing in the a, b and c directions of the first geometry optimization is less than 0.001;

[0101] Step 11. Energy calculation of single-element unit cell model: Use the Energy task in the CASTEP module of MaterialsStudio to perform energy calculation on the single-element unit cell model after structural optimization in step 10. The cutoff energy, convergence accuracy, pseudopotential, and k-point used in the energy calculation are consistent with the minimum volume deviation value of the unit cell after geometric structure optimization in step 10. The final calculated energy is divided by the number of atoms in the supercell to obtain the energy of a single atom when it constitutes a single substance.

[0102] Step 12: Calculation of the binding energy and formation enthalpy of the second phase: Using the unit cell energy obtained in step 3 and the single atom energy obtained in step 7, the binding energy and formation enthalpy of each second phase are calculated by corresponding formulas;

[0103] The calculation formula of the binding energy in step 12 is:

[0104]

[0105] In formula 1: E coh is the binding energy, in eV·atom -1 ; is the total energy of the crystal, in eV·atom -1 ; and is the energy of a single free-state atom of A, B, or C, in eV·atom -1 ; N A 、N B and N C is the number of A, B, and C atoms in the primitive cell.

[0106] The calculation formula for the formation enthalpy described in step 12 is:

[0107]

[0108] In formula 2: ΔH is the binding energy, the unit is eV·atom -1 , where: is the total energy of the crystal, in eVatom -1 ; and The average energy of each atom in the single substances A, B, and C, in eVatom -1 ; N A 、N B and N C is the number of A, B, and C atoms in the primitive cell.

[0109] Table 2

[0110]

[0111] Table 2 shows the binding energy and formation enthalpy of the second phase calculated in step 12 of Example 1. Table 2 shows the stability and alloying ability of each second phase. The formation enthalpy of all second phases is negative and can exist stably. The formation of each second phase is ranked from difficult to easy according to the size of the formation enthalpy: MgZn2>Al2Cu>Mg2Zn11>Al2CuMg>Al3Sc>Al3Zr. The structural stability of each phase is ranked from weak to strong: MgZn2 <Al2Cu<Mg2Zn11<Al2CuMg<Al3Sc<Al3Zr。

[0112] Step 13. Calculation of alloy equilibrium solidification process: Use the oneaxisequilibrium module in termo-calc software to calculate the composition of the 7 series aluminum alloy to be optimized: select the Al alloy database, select Al, Zn, Mg, Cu, Zr, Sc as the calculation objects, specify the system pressure and system size for calculation, specify the element composition unit as mass fraction, set the element composition, the calculation type as uniaxial calculation, the x-axis variable as temperature, specify the calculation range and step size, and perform the calculation;

[0113] In step 13, the system pressure is 101325Pa; the calculated system size is 1 mol; the element composition is Zn: 11.3wt%, Mg: 2.45wt%, Cu: 1.5wt%, Zr: 0.15wt%, Sc: 0.15wt%, Al: Bal.; the calculation range is 0℃-900℃; the step length is 10℃;

[0114] Step 14. Calculation of alloy non-equilibrium solidification process: Use the Scheil Solidification module in the termo-calc software, select the Al alloy database, select Al, Zn, Mg, Cu, Zr, and Sc as the calculation objects, specify the initial calculation temperature and calculation step, specify the element composition unit as mass fraction, set the element composition, and use the classic Scheil model as the calculation model to perform the calculation;

[0115] In step 14, the initial calculation temperature is 900°C, the calculation step is 10°C; the element composition is Zn: 11.3wt%, Mg: 2.45wt%, Cu: 1.5wt%, Zr: 0.15wt%, Sc: 0.15wt%, Al: Bal.; Bal. represents the remainder;

[0116] Step 14: By calculating the non-equilibrium solidification process of alloys with different compositions, it can be used to predict the influence of the non-equilibrium solidification process of spray forming on the alloy solidification structure. Figure 5It can be seen that under non-equilibrium solidification conditions, the precipitation order of the second phase is Al3Zr phase, Al3Sc phase, T phase, V phase, and MgZn2 phase. Compared with the equilibrium solidification process, the alloy appears V phase during the equilibrium solidification process, while the precipitation order of other second phases is the same, which indicates that non-equilibrium solidification will affect the types of solidification precipitation phases of the alloy, but has little effect on the solidification precipitation order.

[0117] Step 15. Calculate the alloy phase diagram: Use the phasediagram module in the termo-calc software, select the Al alloy database, select Al, Zn, Mg, Cu, Zr, and Sc as the calculation objects, specify the calculation system pressure and system size, specify the calculation type as phase diagram calculation, specify the x-axis variable as the element mass fraction, the y-axis as the temperature, adjust the calculation step size and the element calculation range, perform the first calculation, and after the calculation is completed, change the element type and calculate again, repeating the calculation process until all elements are calculated.

[0118] In step 15, the system pressure is 101325Pa; the system size is 1mol; the temperature calculation range is 0°C-900°C; the calculation step is 10°C; Zn, Mg, Cu, the calculation range of Zn element is 6wt%-16wt%, the calculation range of Mg element is 0wt%-10wt%, the calculation range of Cu element is 0wt%-10wt%, and the x-axis calculation step is 0.5wt%;

[0119] Step 15: By calculating the alloy phase diagram, the content of each alloy element can be optimized. This provides an efficient and inexpensive approach for the design of spray-formed ultra-high-strength aluminum alloys, and helps the application of spray-formed ultra-high-strength aluminum alloys in major engineering structural parts. Figures 6 to 11 It can be seen that the solidification path of the alloy under equilibrium solidification conditions is: liquid+Al3Zr→liquid+Al3Zr+Fcc→liquid+Al3Zr+Fcc+Al3Sc→liquid+Fcc+Al3Sc→Fcc+Al3Sc+MgZn2→Fcc+Al3Sc+MgZn2+Al3Zr→Fcc+Al3Sc+MgZn2+Al3Zr+Al2Cu;

[0120] Depend on Figures 6 to 11It can be seen that Mg is the most important factor affecting the type and amount of the second phase in the ultra-high strength aluminum alloy, and Cu has a greater influence on the change in the amount of Al2Cu phase. If you want to reduce the amount of insoluble second phase in the alloy and enhance the strengthening effect of the second phase, you need to increase the Mg content and ensure that the Mg content is not higher than 3.0wt% to prevent the precipitation of T phase, and ensure that the Cu content is as low as possible and not lower than 1wt% to prevent the precipitation of T phase and ensure the content of Sc. If the Zn content is too low (<9.3wt), S phase and T phase will be formed in the alloy, and the proportion of Al2Cu phase in the alloy will be reduced. If the Zn content is too high (>11.8), V phase will appear in the final product of the alloy, and the amount of Al2Cu phase will increase.

[0121] For the Al-Zn-Mg-Cu alloy system, if you want to take into account the toughness and hardness of the material, you need to balance the content of the brittle and tough second phases. Therefore, the MgZn2 phase with strong toughness and low strength is used as the main strengthening phase, and the Al3Zr phase and Al3Sc phase with high strength and poor toughness are used as strength supplementary phases. The Mg element is the most important factor affecting the type and amount of the second phase in the ultra-high strength aluminum alloy. Its content controls the amount of the main strengthening phase MgZn2 phase in the alloy, and determines whether the V phase and T phase can be formed; the content of the main alloying elements does not affect the amount of Al3Zr phase and Al3Sc phase in the alloy.

[0122] Based on the comprehensive calculation results, it is believed that Zn: 9.3wt%-11.8wt%, Mg: 2.75wt%-2.9wt%, Cu: 1.0wt%-1.25wt%, Zr: 0.15wt%, and Sc: 0.15wt% are the preferred alloy components.

Claims

1. A method for optimizing the composition of spray-formed ultra-high strength 7-series aluminum alloy using thermodynamic calculations, characterized in that: The method of optimizing the composition of the spray-formed ultra-high strength 7 series aluminum alloy by thermodynamic calculation is carried out in the following steps: Step 1: Import the second phase unit cell model: Use FindIt software to find the unit cell model of the second phase in the alloy, and import the unit cell model of the second phase into the first principle calculation software MaterialsStudio; Step 2: Geometry optimization: The geometry of the unit cell model of the second phase is optimized through the Geometry Optimization task in the CASTEP module of Materials Studio. The calculation method of correlation energy in geometry optimization uses the PBE functional in the generalized gradient approximation method. Set the quality to the best; set the cutoff energy, convergence accuracy, pseudopotential and k-point, and perform the first structural optimization; after the first structural optimization, compare and record the volume deviation of the unit cell before and after the calculation; reset the cutoff energy, increase the k-point, keep the convergence accuracy and pseudopotential unchanged, and perform structural optimization again; after performing structural optimization again, compare and record the volume deviation of the unit cell before and after the calculation, and repeat the optimization until the volume deviation of the unit cell is minimized; The cutoff energy for the first geometry optimization in step 2 is set to 400 eV, and the cutoff energy for each subsequent geometry optimization is increased by 50 eV; the convergence accuracy of the first geometry optimization is set to SCFtolerance 5e-7; the pseudopotential for the first geometry optimization is an ultrasoft pseudopotential; the k-point is composed of the unit cell constants a, b and c of the second phase, and the actual spacing between a, b and c in the first geometry optimization is less than 0.001; Step 3. Calculation of unit cell energy: Use the Energy task in the CASTEP module of MaterialsStudio to perform energy calculation on the second-phase unit cell model after structural optimization in step 2. The cutoff energy, convergence accuracy, pseudopotential and k-point used in the energy calculation are consistent with the minimum volume deviation value of the unit cell after geometric structure optimization in step 2. After the energy calculation, record the number of elements in the unit cell and the final energy. Step 4. Calculation of unit cell elastic constants: Use the ElasticConstants task in the CASTEP module of MaterialsStudio to calculate the elastic constants of the second-phase unit cell model after the structural optimization in step 2. The number of stresses in each step of the calculation is set to 6, and the cutoff energy, convergence accuracy, pseudopotential, and k-point are consistent with the minimum volume deviation value of the unit cell after the geometric structure optimization in step 2. Step 5. Calculation of mechanical properties of each phase of the unit cell: Analyze the file calculated in step 4 through the Analysis task in the CASTEP module of MaterialsStudio, and calculate the bulk modulus, shear modulus, Young's modulus and Poisson's ratio of the unit cell using elastic constants; Step 6. Establish the single atomic structure of each element in the alloy: Use Materials Studio to build a model of a single atom, select 3D Atomistic in new Document, establish a 3D atomic model, use the Build module to create a cubic empty package without atoms, use the AddAtoms module to add atoms to the cubic empty package, and set the position of the atom to the center of the cube; In step 6, the side length of the cubic empty bag is a: b: c: The space group is P1; the atoms added to the cubic empty package using the AddAtoms module are Al, Zn, Mg, Cu, Zr, and Sc; the atomic positions are a: 0.5, b: 0.5, c: 0.5, and the atomic position is the center of the cube; Step 7. Calculation of single atom energy: Calculate the energy of a single atom through the Energy task in the CASTEP module of MaterialsStudio. Select Ultra-fine for Quality. The calculation method of correlation energy uses the PBE functional in the generalized gradient approximation method. The pseudopotential is set to ultrasoft pseudopotential, the k-point is set to Gammapointonly, the spin is turned on, the Metal option is unchecked, and the apparent spin is used as the initial spin. Step 8. Importing the unit cell model of the element: Use the FindIt software to find the unit cell model of each element in the alloy, and import it into the first principle calculation software MaterialsStudio; Step 9: Establish the supercell structure of the element single-substance model: Use the Supercell module of MaterialsStudio to establish a single-substance supercell and set the supercell range; Step 10. Optimize the geometric structure of the single-element unit cell model: Use the GeometryOptimization task in the CASTEP module of MaterialsStudio to optimize the geometric structure of the single-element unit cell model. The correlation energy is calculated using the PBE functional in the generalized gradient approximation method. Set the cutoff energy, convergence accuracy, pseudopotential and k-point, and perform the first geometry optimization; after the first geometry optimization, compare and record the volume deviation of the unit cell before and after the calculation; reset the cutoff energy, increase the k-point, keep the convergence accuracy and pseudopotential unchanged, and perform the structure optimization again; after performing the structure optimization again, compare and record the volume deviation of the unit cell before and after the calculation, and repeat the optimization until the volume deviation of the unit cell is minimized; The cutoff energy of the first geometry optimization in step 10 is set to 100 eV, and the cutoff energy is increased by 50 eV each time the geometry optimization is performed thereafter; the convergence accuracy of the first geometry optimization is set to SCFtolerance 5e-7; the pseudopotential of the first geometry optimization is an ultrasoft pseudopotential; the k-point is composed of the unit cell constants a, b and c of the second phase, and the actual spacing in the a, b and c directions of the first geometry optimization is less than 0.001; Step 11. Energy calculation of single-element unit cell model: Use the Energy task in the CASTEP module of MaterialsStudio to perform energy calculation on the single-element unit cell model after structural optimization in step 10. The cutoff energy, convergence accuracy, pseudopotential, and k-point used in the energy calculation are consistent with the minimum volume deviation value of the unit cell after geometric structure optimization in step 10. The final calculated energy is divided by the number of atoms in the supercell to obtain the energy of a single atom when it constitutes a single substance. Step 12: Calculation of the binding energy and formation enthalpy of the second phase: Using the unit cell energy obtained in step 3 and the single atom energy obtained in step 7, the binding energy and formation enthalpy of each second phase are calculated by corresponding formulas; Step 13. Calculation of alloy equilibrium solidification process: Use the oneaxisequilibrium module in termo-calc software to calculate the composition of the 7 series aluminum alloy to be optimized: select the Al alloy database, select Al, Zn, Mg, Cu, Zr, Sc as the calculation objects, specify the system pressure and system size for calculation, specify the element composition unit as mass fraction, set the element composition, the calculation type as uniaxial calculation, the x-axis variable as temperature, specify the calculation range and step size, and perform the calculation; In step 13, the system pressure is 101325Pa; the calculated system size is 1 mol; the element composition is Zn: 11.3wt%, Mg: 2.45wt%, Cu: 1.5wt%, Zr: 0.15wt%, Sc: 0.15wt%, Al: Bal.; the calculation range is 0℃-900℃; the step length is 10℃; Step 14. Calculation of alloy non-equilibrium solidification process: Use the Scheil Solidification module in the termo-calc software, select the Al alloy database, select Al, Zn, Mg, Cu, Zr, and Sc as the calculation objects, specify the initial calculation temperature and calculation step, specify the element composition unit as mass fraction, set the element composition, and use the classic Scheil model as the calculation model to perform the calculation; Step 15. Calculate the alloy phase diagram: Use the phasediagram module in termo-calc software, select the Al alloy database, select Al, Zn, Mg, Cu, Zr, and Sc as the calculation objects, specify the calculation system pressure and system size, the calculation type is phase diagram calculation, specify the x-axis variable as the element mass fraction, the y-axis as the temperature, adjust the calculation step size and the element calculation range, perform the first calculation, after the calculation is completed, change the element type, calculate again, and repeat the calculation process until all elements are calculated; In step fifteen, the system pressure is 101325Pa; the system size is 1 mol; the temperature calculation range is 0℃-900℃; the calculation step is 10℃; Zn, Mg, Cu, the calculation range of Zn element is 6wt%-16wt%, the calculation range of Mg element is 0wt%-10wt%, the calculation range of Cu element is 0wt%-10wt%, and the x-axis calculation step is 0.5wt%.

2. The method for optimizing the composition of the spray-formed ultra-high strength 7-series aluminum alloy by thermodynamic calculation according to claim 1, characterized in that: The alloy described in step 1 is 7 series aluminum alloy.

3. The method for optimizing the composition of the spray-formed ultra-high strength 7-series aluminum alloy by thermodynamic calculation according to claim 1, characterized in that: The second phase in step 1 includes Al2CuMg, Al2Cu, MgZn2, Mg2Zn 11 , Al3Sc, Al3Zr.

4. The method for optimizing the composition of the spray-formed ultra-high strength 7-series aluminum alloy by thermodynamic calculation according to claim 1, characterized in that: The process of improving k-point in step 2 is as follows: first increase the value of a by 1, and select the values ​​of b and c from 1 to 8. If the actual spacing of a, b, and c after adjustment is less than 0.001, stop adjusting for structural optimization; If the actual spacing of a, b, and c after adjustment is greater than 0.001, the value of a is increased by 1, and the values ​​of b and c are selected from 1 to 8 until the actual spacing of a, b, and c is less than 0.

001.

5. The method for optimizing the composition of the spray-formed ultra-high strength 7-series aluminum alloy by thermodynamic calculation according to claim 1, characterized in that: The single elements in step eight include Al, Zn, Mg, Cu, Zr, and Sc.

6. The method for optimizing the composition of the spray-formed ultra-high strength 7-series aluminum alloy by thermodynamic calculation according to claim 1, characterized in that: In step 9, the supercell range is set to: A: 2, and the a-axis direction of the unit cell is expanded by 2 times; B: 2, the b-axis direction of the unit cell is expanded by 2 times; C: 2, the c-axis direction of the unit cell is expanded by 2 times.

7. The method for optimizing the composition of the spray-formed ultra-high strength 7-series aluminum alloy by thermodynamic calculation according to claim 1, characterized in that: The process of improving k-point in step 10 is as follows: first, the value of a is increased by 1, and the values ​​of b and c are selected from 1 to 8. If the actual spacing of a, b, and c after adjustment is less than 0.001, the adjustment is stopped for structural optimization; If the actual spacing of a, b, and c after adjustment is greater than 0.001, the value of a is increased by 1, and the values ​​of b and c are selected from 1 to 8 until the actual spacing of a, b, and c is less than 0.

001.

8. The method for optimizing the composition of the spray-formed ultra-high strength 7-series aluminum alloy by thermodynamic calculation according to claim 1, characterized in that: The calculation formula of the binding energy in step 12 is: In formula 1: E coh is the binding energy, in eV·atom -1 ; is the total energy of the crystal, in eV·atom -1 ; and is the energy of a single free-state atom of A, B, or C, in eV·atom -1 ; N A 、N B and N C is the number of A, B, and C atoms in the primitive cell.

9. The method for optimizing the composition of the spray-formed ultra-high strength 7-series aluminum alloy by thermodynamic calculation according to claim 1, characterized in that: The calculation formula for the formation enthalpy described in step 12 is: In formula 2: ΔH is the binding energy, the unit is eV·atom -1 , where: is the total energy of the crystal, in eV·atom -1 ; and is the average energy of each atom in the single substances A, B, and C, in units of eV·atom -1 ; N A 、N B and N C is the number of A, B, and C atoms in the primitive cell.

10. The method for optimizing the composition of the spray-formed ultra-high strength 7-series aluminum alloy by thermodynamic calculation according to claim 1, characterized in that: In step 14, the initial calculation temperature is 900°C, the calculation step is 10°C; the element composition is Zn: 11.3wt%, Mg: 2.45wt%, Cu: 1.5wt%, Zr: 0.15wt%, Sc: 0.15wt%, Al: Bal.

Images