A method for synergistic control of shape memory alloy point defects and magnetic configuration

Abstract

The application discloses a kind of shape memory alloy point defects and magnetic configuration Synergistic control method, belong to new material technical field, it is related to a kind of calculation simulation method based on density functional theory.The application first constructs the crystal structure of shape memory alloy containing point defects in parent phase by Materials Studio software, with the aid of vaspkit software under Linux system, its file type is changed into.vasp format.Point defect and magnetic configuration are synergistically controlled in the constraint condition, the formation energy of ferromagnetic and ferrimagnetic structure is quantified respectively, and the physical properties of the final product are predicted by the tetragonal distortion method.The application can accurately design the alloy defect type at atomic scale, determine the optimal crystal configuration of point defects, and clarify the root cause of the influence of point defects on the stability of parent phase from the perspective of electronic state density, thereby achieving the purpose of accurately controlling the physical properties of alloy.

Description

Technical Field

[0001] This invention relates to the field of new materials technology, and to a method for synergistic control of point defects and magnetic configuration in shape memory alloys. Background Technology

[0002] Shape memory alloys are a class of alloy materials that can "remember" their initial shape when temperature or other conditions change. Due to their significant strain output and driving force, shape memory alloys have been used in the aerospace field for over fifty years. In 1969, shape memory alloy pipe fittings were successfully applied to the fuel lines of the American F-14 fighter jet. Since then, mechanisms and structures designed using shape memory alloys have been gradually applied to various aspects of the aerospace field, such as space compression release mechanisms, geometric adjustment of aero-engine air intakes, morphing aircraft, and vibration dampers.

[0003] However, intrinsic defects are unavoidable in alloy materials, and these defects significantly affect the physical properties of the alloy, such as crystal structure, phase stability, martensitic phase transformation, and magnetic properties. Hu Qingmiao et al. studied TiNi using the Exact Muffin-tin Orbitals (EMTO) method combined with approximate calculations of coherent potential. 1-x Zr x Atomic occupancy and patterns in alloys were investigated. Results showed that Zr atoms preferentially occupied Ti atom positions, while Ti atoms moved to Ni atom positions. Li et al. and Ghosh et al. modified the annealing temperature and time to influence the atomic occupancy of CoMnSb and Ni alloys. 50 Mn 36.5 Sn 13.5 The magnetocaloric properties of the alloy were explored, and the results showed that the magnetocaloric properties of the alloy were significantly improved, which may be related to internal defects in the alloy.

[0004] Most existing methods for improving the physical properties of alloy materials are achieved through element doping. However, for magnetic materials, these methods only calculate the physical properties of the ferromagnetic state configuration, neglecting the subferromagnetic state configuration. Therefore, we propose a synergistic control method for point defects and magnetic configurations in shape memory alloys. By synergistically controlling multiple point defects and magnetic configurations within the alloy, we can achieve both computational accuracy and excellent material properties without the need for doping with other elements. This has theoretical guiding significance for the development and application of shape memory alloys in aerospace fields such as vari-propelled aircraft, pipe fittings, and vibration dampers. Summary of the Invention

[0005] The purpose of this invention is to address the problems existing in the prior art by providing a method for synergistic control of point defects and magnetic configurations in shape memory alloys. First-principles calculations are used to determine the formation energy and tetragonal distortion curves of defect crystals under different magnetic configurations. The magnetic moment information and martensitic phase transformation path of the system are analyzed based on electronic structure information. This method can significantly reduce the gap between calculated and experimental results, ensure computational accuracy, and improve the overall performance of shape memory alloys.

[0006] To achieve the objectives of the invention described above, the technical solution adopted by this invention is as follows: a method for synergistic control of point defects and magnetic configuration in shape memory alloys, comprising the following steps:

[0007] Step 1: Construct the austenitic unit cell of the shape memory alloy using Materials Studio software, and then introduce point defects to construct the input file POSCAR for VASP calculation.

[0008] Step 2: During the calculation process, ferromagnetic and subferromagnetic states are calculated for each defect condition of the alloy. Within the constraints, the ground state energy and formation energy of the alloy structure are quantified to determine the magnetic configuration of the austenite parent phase of the alloy.

[0009] The constraints are the interatomic forces and external pressures during the structural relaxation process, as well as the types of point defects, including vacancies, inversions, and substitutions. The formation energy is obtained by substituting the formation energy formula into the total ground state energy of the system and the ground state energy of each atom. The ground state energy is the energy of structural relaxation under the constraints.

[0010] Step 3: Repeat the above steps, change the variables within the constraints, coordinate the control of point defects and magnetic configuration, analyze the formation energy and magnetic properties under different defects, and play a role in controlling the physical properties of shape memory alloys.

[0011] Step 4: Calculate the tetragonal distortion and electronic density of states of the austenitic parent phase of the alloy, predict the influence of point defects on the martensitic phase transformation and magnetic properties of the alloy, and reveal the fundamental reasons for the changes in phase stability and magnetic properties from the perspective of electronic density of states.

[0012] The tetragonal distortion described herein refers to applying a specific stress to the relaxed austenitic structure, causing it to transform from a highly ordered cubic structure to a tetragonal structure. The volume of the cubic structure is set to V, and its lattice constant to a0. The lattice constants of the tetragonal structure are a and c, with a and c having a relationship of c = (1 + δ)a. During the tetragonal distortion calculation, based on the principle of constant cell volume, the austenitic structure is subjected to lattice distortion with different tetragonal distortion rates c / a, and its atomic positions are optimized. The total energy of the ground state of the alloy system is calculated, and then the tetragonal distortion curve is plotted.

[0013] Preferably, the .CIF format file is exported using Materials Studio software, and then converted into .vasp format using the vaspkit software under the Linux system.

[0014] Preferably, the shape memory alloy is selected from X m Y n Z p The alloy system.

[0015] Preferably, the formula for calculating the quantization formation energy is as follows:

[0016]

[0017] Among them, E f E represents the formation energy (eV / atom) of the alloy system. total E represents the total energy of the ground state (eV); X E Y E Z denoted as , respectively, representing the total ground state energy of pure elements X, Y, and Z, and m, n, and p representing the number of atoms of pure elements X, Y, and Z, respectively.

[0018] Preferably, a vacancy site defect refers to a vacancy left by an atom in a unit cell after leaving a sublattice point; an anti-site defect refers to a defect formed by one atom occupying a sublattice point of another atom in a unit cell; and a substitution point defect refers to a defect in which sublattice points of different types of atoms in a unit cell are interchanged.

[0019] Preferably, the magnetic state of the austenite phase is divided into ferromagnetic state and subferromagnetic state. Ferromagnetic state refers to the fact that the spin magnetization direction of the magnetic atoms is uniform. Subferromagnetic state refers to the fact that the spin magnetization direction of the normal atoms and the excess atoms in the magnetic atoms is opposite.

[0020] Preferably, the normal atom refers to an atom located at the initial sublattice point of the stoichiometric alloy cell; the excess atom refers to an atom that is not located at the initial sublattice point of the stoichiometric alloy cell.

[0021] Preferably, the calculation of the ground state energy of the unit cell system is based on the VASP simulation software package using the plane-wave pseudopotential method within the framework of density functional theory. During the calculation, the generalized gradient approximation (GGA) method under projected fused wave (PAW) is used to describe the exchange correlation function, while simultaneously employing... An improved tetrahedral point-integral method was used to implement the K-point mesh setup. The cutoff energy during structural relaxation was set to 1.3 times the maximum cutoff energy of pure elements in the system. The convergence criteria for the total energy and interatomic forces were set to 1 meV and 1 meV, respectively. Both together form the basis for judging whether structural relaxation has been completed.

[0022] Preferably, the K-point grid setting needs to undergo convergence testing. Different K-point grid settings are applied to the same system, and the optimal K-point grid is determined by balancing time and accuracy factors through the formation energy calculation formula.

[0023] Compared with the prior art, the technical solution of the present invention has the following beneficial technical effects:

[0024] 1. The method of this invention can overcome the traditional "stir-fry" experimental approach, save resources and time, and achieve the goal of high-efficiency screening of alloy components by calculating and coordinating the point defects and magnetic configuration of shape memory alloys based on first-principles calculations.

[0025] 2. The method of the present invention only requires the atomic position information of the alloy system to obtain the formation energy parameters of the shape memory alloy. It is simple to operate, low in cost, easy to implement, and suitable for widespread application.

[0026] 3. The method of the present invention only requires the unit cell information of the parent phase of the alloy system. The trend of the martensitic phase transformation path and the martensitic phase transformation temperature can be predicted by tetragonal distortion calculation. Selecting qualified samples for experimental verification can effectively save experimental costs.

[0027] 4. The method of this invention can effectively compensate for the lack of understanding of the physical properties of materials during the application process by calculating the electronic structure, and provide a better reference for improving the performance of alloys from the root. Attached Figure Description

[0028] Figure 1 This is a schematic diagram of the austenitic phase crystal structure and magnetic configuration of the Ni8Mn6In2 alloy in the embodiment.

[0029] Figure 2 This is a convergence test of the K-point mesh of the austenitic phase of the Ni8Mn6In2 alloy in the example.

[0030] Figure 3 The formation energy of the austenitic phase in Ni8Mn6In2 alloy under the synergistic regulation of point defects and magnetic configuration is shown in the example.

[0031] Figure 4 The total magnetic moment of the austenitic phase of the Ni8Mn6In2 alloy under different point defects in the most stable magnetic configuration in the examples is represented.

[0032] Figure 5 The tetragonal distortion curve of the Ni9Mn6In1 alloy under the most stable magnetic configuration in the example with antisite defects is shown.

[0033] Figure 6 The density of electronic states of the Ni9Mn6In1 alloy with antisite defects under the most stable magnetic configuration in the examples. Detailed Implementation

[0034] To enable those skilled in the art to better understand and implement the technical solutions of the present invention, the present invention will be described in detail below with reference to the accompanying drawings and specific examples, but the embodiments given are not intended to limit the present invention.

[0035] This invention proposes a method for the coordinated control of point defects and magnetic configuration in shape memory alloys. A crystal structure of the shape memory alloy containing point defects as the parent phase is constructed using Materials Studio software, and the file type is converted to .vasp format using the vaspkit software under Linux. The austenitic parent phase crystal model and magnetic configuration are coordinated and controlled. The formation energies of ferromagnetic and subferromagnetic austenite are quantified separately under constraints, and the physical properties of the final product are predicted using the tetragonal distortion method. This invention allows for the precise design of alloy defect types at the atomic scale, clarifies the optimal crystal configuration of point defects, and elucidates the fundamental reasons for the influence of point defects on the stability of the parent phase from the perspective of electronic density of states, thereby achieving the goal of precisely controlling the physical properties of the alloy.

[0036] Example 1:

[0037] A method for synergistic control of point defects and magnetic configuration in shape memory alloys, see [link to relevant documentation]. Figures 1-6 As shown, it includes the following steps:

[0038] Step 1: Construction of a defect model for a shape memory alloy system with the molecular formula Ni8Mn6In2.

[0039] Since the stoichiometric Ni2MnIn alloy does not undergo martensitic phase transformation and therefore does not possess shape memory effect, the non-stoichiometric Ni8Mn6In2 alloy was chosen as the specific example. The austenitic phase point defects in the non-stoichiometric Ni8Mn6In2 alloy system are mainly classified into three categories: vacancies, antisites, and substitutions, totaling fourteen defect models. Vacancy point defects include: V-Ni, V-Mn1-1, V-Mn1-2, V-Mn2-1, V-Mn2-2, and V-In; antisite defects include: Ni9Mn6In1, Ni7Mn6In3, and Ni6Mn6In4; substitution point defects include: Ni-Mn1, Ni-Mn2, Ni-In, Mn1-In, and Mn2-In.

[0040] The austenite unit cell of the non-stoichiometric Ni8Mn6In2 alloy has two excess Mn atoms occupying two sublattice points of In atoms, compared to the Ni2MnIn alloy. In the magnetic configuration setting, for the ferromagnetic state, the initial magnetic moments of all Mn atoms with Ni and In atoms are set to positive directions; for the subferromagnetic state, the initial magnetic moments of the four normal Mn atoms with Ni and In atoms are set to positive directions, and the initial magnetic moments of the two excess Mn atoms are set to negative directions. The initial magnetic moment of each atom is empirically set to 2 μm. B 5μ B 1μ B Taking the austenitic unit cell of Ni8Mn6In2 alloy as an example, the specific settings for the ferromagnetic state in the POSCAR file are: MAGMOM = 8*2 4*5 2*5 2*1; the specific settings for the hypoferromagnetic state are: MAGMOM = 8*2 4*5 2*-52*1. The atomic diagram is shown below. Figure 1 As shown.

[0041] Materials Studio, a crystal structure 3D visualization software, was used to construct austenite unit cells and defects such as vacancies, antisites, and substitution points in Ni8Mn6In2 alloy. The .cif file was converted into a .vasp file using the VASPkit software based on the Linux system, forming the POSCAR input file required for VASP calculation. At the same time, the VASPkit software was used to generate the initial INCAR, KPOINT, and POTCAR files.

[0042] Step 2: Calculate the ground state energy and formation energy of ferromagnetic and subferromagnetic states for each of the above point defect conditions to determine the most stable magnetic configuration of the alloy austenite parent phase.

[0043] Some key parameters are as follows: The interaction between ions and electrons is described using the PAW method during the calculation, and the exchange correlation potential between electrons is handled using the PBE approximation method under GGA. Simultaneously, the following methods are employed... An improved tetrahedral point-integral method was used to implement the K-point mesh setup. The cutoff energy during structural relaxation was set to 1.3 times the maximum cutoff energy of pure elements in the system, i.e., ENMAX = 351 eV. The convergence criteria for total energy and interatomic forces were set to 1 meV and 1 eV, respectively. Both of these factors together form the basis for determining whether structural relaxation is complete. The system's ground-state energy and magnetic moment are then read from the output file OSZICAR.

[0044] Convergence tests were performed on the K-point grid. Ground-state total energy was calculated using K-point grids of 4×4×4, 6×6×6, 8×8×8, 10×10×10, 12×12×12, 14×14×14, and 16×16×16, respectively. The results are as follows: Figure 2 As shown, balancing time and accuracy factors determines the optimal K-point grid as 10×10×10.

[0045] Modify the key parameters of the initial input files INCAR and KPOINTS generated in step 1.

[0046] The formation energy is calculated according to the following formula:

[0047]

[0048] Among them, E f E represents the formation energy (eV / atom) of the alloy system. total E represents the total energy of the ground state (eV); X E Y E Z represents the total ground state energy of pure elements Ni, Mn, and In, respectively, and m, n, and p represent the number of atoms of pure elements X, Y, and Z, respectively.

[0049] Therefore, the formation energy of the austenite phase under various point defects in the alloy system was calculated, such as... Figure 3 As shown.

[0050] Step 3: Repeat the above steps, change the type of point defect within the constraints, coordinate and control the magnetic configuration, analyze the formation energy and magnetic properties under different defects, and play a role in regulating the physical properties of shape memory alloys.

[0051] The constraints are the interatomic forces and external pressures during the structural relaxation process, as well as the types of point defects, including vacancies, inversions, and substitutions.

[0052] Step 4: Select the austenitic phase with the most stable magnetic configuration under various point defects, calculate the tetragonal distortion and electronic density of states of the alloy austenitic phase, and predict the influence of point defects on the martensitic phase transformation and magnetic properties of the alloy.

[0053] The tetragonal distortion described herein refers to applying a specific stress to the relaxed austenitic structure, causing it to transform from a highly ordered cubic structure to a tetragonal structure. The volume of the cubic structure is set to V, and its lattice constant to a0. The lattice constants of the tetragonal structure are a and c, with a and c having a relationship of c = (1 + δ)a. During the tetragonal distortion calculation, based on the principle of constant unit cell volume, the austenitic structure is subjected to lattice distortion with different tetragonal distortion rates c / a, and its atomic positions are optimized. The total ground-state energy of the alloy system is calculated, and then the tetragonal distortion curve is plotted.

[0054] For the Ni8Mn6In2 alloy system in this example, by using a method of synergistic control of vacancies, antisites, substitution point defects, and magnetic configuration, the most stable state of the alloy system's point defects and magnetic configuration can be accurately analyzed. Furthermore, the fundamental reasons can be deeply analyzed from the perspective of electronic structure, thereby achieving the goal of precisely controlling the alloy's physical properties. The analysis process is as follows:

[0055] Figure 1 This is a schematic diagram of the austenitic phase crystal structure and magnetic configuration of the Ni8Mn6In2 alloy.

[0056] from Figure 2 As can be seen, when the K-point is greater than 6×6×6, the ground-state energy of the alloy fluctuates within a certain range, reaching its minimum value with a 16×16×16 K-point grid. A larger K-point results in higher calculation accuracy but longer computation time under the same service configuration. The calculation results show that the ground-state energy of the alloy with a 10×10×10 K-point grid differs from that with a 16×16×16 K-point grid by only 0.3 meV. Therefore, to balance computational accuracy and time cost, a 10×10×10 K-point grid is used for all austenite unit cells.

[0057] from Figure 3 As can be seen, for vacancy defects, the formation energies of the ferromagnetic and subferromagnetic states are very similar under V-Ni defects, with a difference of only 0.39 meV / atom, indicating that the austenite phase exhibits a coexistence of ferromagnetic and subferromagnetic states. Therefore, it can be determined that vacancy defects preferentially occupy the sublattice points of Ni with smaller atomic radii, and the phase stability of austenite gradually decreases with increasing atomic radius of the substituted atoms. For antisite defects, the formation energy of the ferromagnetic Ni9Mn6In1 alloy austenite phase is the lowest, indicating that the stability of the austenite phase under antisite defects decreases from high to low as follows: E f (Ni9Mn6In1)>E f (Ni7Mn6In3)>E f (Ni6Mn6In4). For substitution point defects, Ni-Mn2 has the smallest formation energy among substitution defect types in the ferromagnetic state (FM), indicating that the austenitic phase formed after Ni atoms and Mn2 atoms exchange positions is the most stable at high temperatures.

[0058] from Figure 4As can be seen, for vacancy defects, the total magnetic moment of the austenite phase, from high to low, is Mag(V-Mn) > Mag(V-Ni) > Mag(V-In). For anti-site defects, the ferromagnetism of the austenite phase, from high to low, is Mag(Ni9Mn6In1) > Mag(Ni7Mn6In3) > Mag(Ni6Mn6In4). For substitution point defects, the ferromagnetism of the austenite phase, from high to low, is Mag(Mn1-In) = (Mn2-In) > Mag(Ni-Mn2) > Mag(Ni-In) > Mag(Ni-Mn1).

[0059] Taking the inversion defect as an example, calculations of tetragonal distortion and electronic structure were performed. The analysis results show that Ni9Mn6In1 and Ni6Mn6In4 alloys underwent a magnetic-structural coupling transformation from a ferromagnetic austenite phase to a subferromagnetic martensite phase; the Ni7Mn6In3 alloy did not undergo a significant martensitic magnetic-structural coupling phase transformation, but a modulated martensitic transformation may exist. The tetragonal distortion curve of the Ni9Mn6In1 alloy is used as a schematic diagram, as shown below. Figure 5 As shown.

[0060] from Figure 6 As can be seen from the data, the total density of states curves of the spin-up and spin-down phases of the ferromagnetic Ni9Mn6In1 alloy have poor symmetry, and the total density of states near the Fermi level is at a peak position, indicating that the total magnetic moment of the alloy is large at this time and the structural stability of the austenite phase is poor.

[0061] Example 2:

[0062] A method for synergistic control of point defects and magnetic configuration in shape memory alloys, comprising the following steps:

[0063] Step 1: Construct the austenitic unit cell of the shape memory alloy using Materials Studio software, and introduce point defects on this basis to construct the input file POSCAR for VASP calculation;

[0064] Step 2: During the calculation process, ferromagnetic and subferromagnetic states are calculated for each defect condition of the alloy. Within the constraints, the ground state energy and formation energy of the alloy structure are quantified to determine the magnetic configuration of the austenite parent phase of the alloy.

[0065] The constraints mentioned above are the interatomic forces and external pressures during the structural relaxation process, as well as the types of point defects, including vacancy point defects, anti-point defects, and substitution point defects. The formation energy is obtained by substituting the formation energy formula into the total ground state energy of the system and the ground state energy of each atom. The ground state energy is the energy of structural relaxation under the constraints.

[0066] Step 3: Repeat the above steps, change the variables within the constraints, coordinate the control of point defects and magnetic configuration, analyze the formation energy and magnetic properties under different defects, and play a role in controlling the physical properties of shape memory alloys.

[0067] Step 4: Calculate the tetragonal distortion and electronic density of states of the austenitic parent phase of the alloy, predict the influence of point defects on the martensitic phase transformation and magnetic properties of the alloy, and reveal the fundamental reasons for the changes in phase stability and magnetic properties from the perspective of electronic density of states.

[0068] The tetragonal distortion is a process of applying a specific stress to a relaxed austenitic structure to induce a transformation from a highly ordered cubic structure to a tetragonal structure. The volume of the cubic structure is set to V, and the lattice constant is a0. The lattice constants of the tetragonal structure are a and c, and a and c are related by c = (1 + δ)a. In the tetragonal distortion calculation, based on the principle of constant cell volume, the austenitic structure is subjected to lattice distortion with different tetragonal distortion rates c / a to optimize the atomic positions. The total energy of the ground state of the alloy system is calculated, and then the tetragonal distortion curve is plotted.

[0069] In step 1, the .CIF format file is exported using Materials Studio software, and then converted into .vasp format using the vaspkit software under the Linux system.

[0070] The shape memory alloy mentioned is X m Y n Z p The alloy system.

[0071] The formation energy formula is as follows:

[0072]

[0073] Among them, E f E represents the formation energy (eV / atom) of the alloy system. total E represents the total energy of the ground state (eV); X E Y E Z denoted as , respectively, representing the total ground state energy of pure elements X, Y, and Z, and m, n, and p representing the number of atoms of pure elements X, Y, and Z, respectively.

[0074] The aforementioned vacancy site defect refers to the vacancy left by an atom in the unit cell after leaving the sublattice point; the anti-site defect refers to the defect formed by one atom occupying the sublattice point of another atom in the unit cell; the substitution point defect refers to the defect in which sublattice points of different types of atoms in the unit cell are interchanged.

[0075] The austenitic parent phase is constructed with unit cells containing all possible vacancies, antisites, and substitutional defects. The magnetic configuration of the austenitic phase is set accordingly. The formation energy of the system is calculated using the formation energy formula.

[0076] The magnetic states of the austenitic parent phase are divided into ferromagnetic and subferromagnetic states. Ferromagnetic states refer to the uniform direction of the spin magnetization of magnetic atoms. Subferromagnetic states refer to the opposite direction of the spin magnetization of normal atoms and excess atoms in magnetic atoms.

[0077] The term "normal atom" refers to an atom located at an initial sublattice point in the unit cell of its stoichiometric alloy; "excess atom" refers to an atom that is not located at an initial sublattice point in the unit cell of its stoichiometric alloy.

[0078] The ground state energy calculation is based on the VASP simulation software package using the plane-wave pseudopotential method within the density functional theory framework. During the calculation, the interaction between ions and electrons is described using the PAW method, and the exchange-related potential between electrons is handled using the PBE approximation method under GGA. An improved tetrahedral point-integral method was used to implement K-point meshing; the cutoff energy in structural relaxation was set to 1.3 times the maximum cutoff energy of pure elements in the system; the convergence criteria for total energy and interatomic forces were set to 1 meV and 1 meV, respectively. Both together form the basis for judging whether structural relaxation has been completed.

[0079] The K-point grid settings described above need to undergo convergence testing. Different K-point grid settings are applied to the same system, and the optimal K-point grid is determined by balancing time and accuracy factors through the formula for calculating the formation energy.

[0080] Obviously, those skilled in the art can make various modifications and variations to this invention without departing from its spirit and scope. Therefore, it is intended to include any modifications and variations that fall within the scope of the claims and their equivalents.

Claims

1. A method for synergistic control of point defects and magnetic configuration in shape memory alloys, characterized in that, Includes the following steps: Step 1: Construct the austenitic unit cell of the shape memory alloy using Materials Studio software, and introduce point defects on this basis to construct the input file POSCAR for VASP calculation; Step 2: During the calculation process, ferromagnetic and subferromagnetic states are calculated for each defect condition of the alloy. Within the constraints, the ground state energy and formation energy of the alloy structure are quantified to determine the magnetic configuration of the austenite parent phase of the alloy. The constraints mentioned above are the interatomic forces and external pressures during the structural relaxation process, as well as the types of point defects, including vacancy point defects, anti-point defects, and substitution point defects. The formation energy is obtained by substituting the formation energy formula into the total ground state energy of the system and the ground state energy of each atom. The ground state energy is the energy of structural relaxation under the constraints. Step 3: Repeat the above steps, change the variables within the constraints, coordinate the control of point defects and magnetic configuration, analyze the formation energy and magnetic properties under different defects, and play a role in controlling the physical properties of shape memory alloys. Step 4: Calculate the tetragonal distortion and electronic density of states of the austenitic parent phase of the alloy, predict the influence of point defects on the martensitic phase transformation and magnetic properties of the alloy, and reveal the fundamental reasons for the changes in phase stability and magnetic properties from the perspective of electronic density of states. The tetragonal distortion is a process of applying a specific stress to a relaxed austenitic structure to induce a transformation from a highly ordered cubic structure to a tetragonal structure. The volume of the cubic structure is set to V, and the lattice constant is a0. The lattice constants of the tetragonal structure are a and c, and a and c are related by c = (1 + δ)a. In the tetragonal distortion calculation, based on the principle of constant cell volume, the austenitic structure is subjected to lattice distortion with different tetragonal distortion rates c / a to optimize the atomic positions. The total energy of the ground state of the alloy system is calculated, and then the tetragonal distortion curve is plotted.

2. The method for synergistic control of point defects and magnetic configuration in shape memory alloys as described in claim 1, characterized in that: In step 1, the .CIF format file is exported using Materials Studio software, and then converted into .vasp format using the vaspkit software under the Linux system.

3. The method for synergistic control of point defects and magnetic configuration in shape memory alloys as described in claim 1, characterized in that: The shape memory alloy mentioned is X m Y n Z p The alloy system.

4. The method for synergistic control of point defects and magnetic configuration in shape memory alloys as described in claim 1, characterized in that: The formation energy formula is as follows: Among them, E f E represents the formation energy (eV / atom) of the alloy system. total E represents the total energy of the ground state (eV); X E Y E Z denoted as , respectively, representing the total ground state energy of pure elements X, Y, and Z, and m, n, and p representing the number of atoms of pure elements X, Y, and Z, respectively.

5. The method for synergistic control of point defects and magnetic configuration in shape memory alloys as described in claim 1, characterized in that: The aforementioned vacancy site defect refers to the vacancy left by an atom in the unit cell after leaving the sublattice point; the anti-site defect refers to the defect formed by one atom occupying the sublattice point of another atom in the unit cell; the substitution point defect refers to the defect in which sublattice points of different types of atoms in the unit cell are interchanged.

6. The method for synergistic control of point defects and magnetic configuration in shape memory alloys as described in claim 4, characterized in that: The austenitic parent phase is constructed with unit cells containing all possible vacancies, antisites, and substitutional defects. The magnetic configuration of the austenitic phase is set accordingly. The formation energy of the system is calculated using the formation energy formula.

7. The method for synergistic control of point defects and magnetic configuration in shape memory alloys as described in claim 6, characterized in that: The magnetic states of the austenitic parent phase are divided into ferromagnetic and subferromagnetic states. The ferromagnetic state refers to the uniform direction of the spin magnetization of magnetic atoms. The subferromagnetic state refers to the opposite direction of the spin magnetization of normal atoms and excess atoms in the magnetic atom.

8. The method for synergistic control of point defects and magnetic configuration in shape memory alloys as described in claim 7, characterized in that: The term "normal atom" refers to an atom located at an initial sublattice point in the stoichiometric alloy cell; "excess atom" refers to an atom not located at an initial sublattice point in the stoichiometric alloy cell.

9. The method for synergistic control of point defects and magnetic configuration in shape memory alloys as described in claim 1, characterized in that: The ground state energy calculation is based on the VASP simulation software package using the plane-wave pseudopotential method within the density functional theory framework. During the calculation, the interaction between ions and electrons is described using the PAW method, and the exchange-related potential between electrons is handled using the PBE approximation method under GGA. An improved tetrahedral point-integral method was used to implement K-point meshing; the cutoff energy in structural relaxation was set to 1.3 times the maximum cutoff energy of pure elements in the system; the convergence criteria for total energy and interatomic forces were set to 1 meV and 1 meV, respectively. Both together form the basis for judging whether structural relaxation has been completed.

10. The method for synergistic control of point defects and magnetic configuration in shape memory alloys as described in claim 9, characterized in that: The K-point grid settings need to undergo convergence testing. Different K-point grid settings are applied to the same system, and the optimal K-point grid is determined by the calculation formula of the formation energy, balancing time and accuracy factors.

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