Dislocation grain boundary interaction atom simulation model and construction method thereof

Abstract

The invention relates to a dislocation grain boundary interaction atom simulation model and a construction method thereof, and the construction method comprises the following steps: constructing a simulation box containing screw dislocation, and carrying out relaxation to obtain a relaxed screw dislocation model; constructing a simulation box containing a crystal boundary, and performing relaxation to obtain a relaxed crystal boundary model; cutting the relaxed screw dislocation model along the z-axis direction until the length of the relaxed screw dislocation model is consistent with the length of the relaxed crystal boundary model along the z-axis direction to obtain a cut screw dislocation model; combining the cut screw dislocation model and the relaxed crystal boundary model along the y-axis direction to obtain a combined model; the merged model is relaxed, and a relaxed merged model is obtained; a loading module is arranged on the upper surface of the relaxed combined model in the z-axis direction, a fixing module is arranged on the lower surface of the relaxed combined model, and the dislocation grain boundary interaction atom simulation model is obtained. The method is mainly used for solving the problem that the screw dislocation and the grain boundary are difficult to construct at the same time.

Description

Technical Field

[0001] The present invention relates to the technical field of metal material simulation, and particularly to an atomic simulation model of dislocation-grain boundary interaction and a construction method thereof. Background Art

[0002] The microstructure of materials has an important influence on the mechanical behavior and properties of materials. Grain boundaries, as important surface defects inside metal materials, their interaction with line defects, dislocations, largely determines the plasticity, fatigue and fracture behavior of materials. Therefore, constructing an atomic simulation model of dislocation-grain boundary interaction is of great significance for understanding and studying the micro-mechanisms of materials.

[0003] The existing first technology discloses a modeling method for the atomic structure of a dislocation line where an edge dislocation and a screw dislocation are vertically connected. The main technical solution recorded therein is as follows: Given a file containing the atomic structure information of a crystal model, according to the Burgers vector, the position of the dislocation line, and the requirements of the slip plane of the atomic structure of the dislocation line where the edge dislocation and the screw dislocation are vertically connected to be constructed, use C / C++ language to extract the atomic structure information of the crystal model in the file, automatically calculate the atomic coordinates of the crystal model containing the atomic structure of the dislocation line where the edge dislocation and the screw dislocation that meet the requirements are vertically connected, and then output the data to a file in a file format recognizable by molecular dynamics software.

[0004] The existing second technology discloses a modeling method for the atomic structure of a triangular wave-shaped dislocation line where screw-edge dislocations are alternately connected. The main technical solution recorded therein is as follows: Given a file containing the atomic structure information of a crystal model, according to the Burgers vector, the position of the dislocation line, the slip plane, and the requirements of the amplitude of the waveform of the atomic structure of the triangular wave-shaped dislocation line where the screw-edge dislocations are alternately connected to be constructed, use C / C++ language to extract the atomic structure information of the crystal model in the file, automatically calculate the atomic coordinates of the crystal model containing the atomic structure of the triangular wave-shaped dislocation line where the screw-edge dislocations that meet the requirements are alternately connected, and then output the data to a file in a file format recognizable by molecular dynamics software. This solution can conveniently and quickly directly construct the atomic structure of a triangular wave-shaped dislocation line where screw-edge dislocations are alternately connected with a specified orientation, configuration, and waveform at a specified position inside the crystal, creating favorable conditions for the precise study of the morphology and behavior of the triangular wave-shaped dislocation line where screw-edge dislocations are alternately connected by molecular dynamics and other computer simulation technologies.

[0005] The existing third technology discloses a modeling method for the atomic structure of a square-wave dislocation line with an edge dislocation as the axis. The main technical solution it records is as follows: Given a file containing the atomic structure information of the crystal model, according to the requirements of the Burgers vector, the position of the dislocation line, the slip plane, the amplitude and wavelength of the waveform of the square-wave dislocation line with an edge dislocation as the axis to be constructed, use the C / C++ language to extract the atomic structure information of the crystal model in the file, automatically calculate the atomic coordinates of the crystal model containing the atomic structure of the square-wave dislocation line with an edge dislocation as the axis that meets the requirements, and then output the data to the file in a file format recognizable by the molecular dynamics software. This solution can conveniently and quickly directly construct the atomic structure of a square-wave dislocation line with an edge dislocation as the axis with a specified orientation, configuration and waveform at a specified position inside the crystal, creating favorable conditions for the accurate study of the morphology and behavior of the square-wave dislocation line with an edge dislocation as the axis by molecular dynamics and other computer simulation technologies.

[0006] The existing fourth technology discloses a modeling method for the atomic structure of a sine-wave dislocation with a mixed dislocation as the axis. The main technical solution it records is as follows: Given a file containing the atomic structure information of the crystal model, according to the requirements of the Burgers vector, the direction and position of the dislocation line, the slip plane, the amplitude and wavelength of the waveform of the sine-wave dislocation with a mixed dislocation as the axis to be constructed, use the programming language to extract the atomic structure information of the crystal model in the file, automatically calculate the atomic coordinates of the crystal model containing the atomic structure of the sine-wave dislocation with a mixed dislocation as the axis that meets the requirements, and then output the data to the file in a file format recognizable by the computer simulation technology. This solution can conveniently and quickly directly construct the atomic structure of a sine-wave dislocation with a mixed dislocation as the axis with a specified orientation, configuration and waveform at a specified position inside the crystal, creating favorable conditions for the accurate study of the morphology and behavior of the dislocation by the computer simulation technology.

[0007] The existing fifth technology discloses a modeling method for the atomic structure of a square-wave dislocation line with a screw dislocation as the axis. The main technical solution it records is as follows: Given a file containing the atomic structure information of the crystal model, according to the requirements of the Burgers vector, the position of the dislocation line, the slip plane, the amplitude and wavelength of the waveform of the square-wave dislocation line with a screw dislocation as the axis to be constructed, use the C / C++ language to extract the atomic structure information of the crystal model in the file, automatically calculate the atomic coordinates of the crystal model containing the atomic structure of the dislocation line that meets the requirements, and then output the data to the file in a file format recognizable by the molecular dynamics software. This solution can conveniently and quickly directly construct the atomic structure of a square-wave dislocation line with a screw dislocation as the axis with a specified orientation, configuration and waveform at a specified position inside the crystal, creating favorable conditions for the accurate study of the morphology and behavior of the square-wave dislocation line with a screw dislocation as the axis by the computer simulation technology.

[0008] The existing sixth technology discloses a modeling method for a sine-wave dislocation atomic structure with an edge dislocation as the axis. The main technical solution recorded is as follows: Given a file containing the atomic structure information of a crystal model, according to the requirements of the Burgers vector, the position of the dislocation line, the slip plane, the amplitude and wavelength of the waveform of the sine-wave dislocation atomic structure to be constructed with an edge dislocation as the axis, use C / C++ language to extract the atomic structure information of the crystal model in the file, automatically calculate the atomic coordinates of the crystal model containing the sine-wave dislocation atomic structure that meets the requirements with an edge dislocation as the axis, and then output the data to a file in a file format recognizable by molecular dynamics software. This solution can conveniently and quickly directly construct a sine-wave dislocation atomic structure with an edge dislocation as the axis with a specified orientation, configuration and waveform at a specified position inside the crystal, creating favorable conditions for the accurate study of the morphology and behavior of dislocations by molecular dynamics.

[0009] The existing seventh technology discloses a modeling method for a sine-wave dislocation atomic structure with a screw dislocation as the axis. The main technical solution recorded is as follows: Given a file containing the atomic structure information of a crystal model, according to the requirements of the Burgers vector, the position of the dislocation line, the slip plane, the amplitude and wavelength of the waveform of the sine-wave dislocation atomic structure to be constructed with a screw dislocation as the axis, use C / C++ language to extract the atomic structure information of the crystal model in the file, automatically calculate the atomic coordinates of the crystal model containing the sine-wave dislocation atomic structure that meets the requirements with a screw dislocation as the axis, and then output the data to a file in a file format recognizable by molecular dynamics software. This solution can conveniently and quickly directly construct a sine-wave dislocation atomic structure with a screw dislocation as the axis with a specified orientation, configuration and waveform at a specified position inside the crystal, creating favorable conditions for the accurate study of the morphology and behavior of dislocations by molecular dynamics.

[0010] Currently, there are many technologies for molecular dynamics simulation modeling of dislocations, but there is almost no technology involving grain boundary modeling, while the demand for grain boundary modeling programs in current academic research is very high. The modeling technology of dislocations has been very mature, but there are still certain difficulties in simultaneously modeling grain boundary dislocations.

[0011] In the simulation experiment of molecular dynamics, it is very difficult to simultaneously construct a screw dislocation and a grain boundary. This is because when forming a screw dislocation, there is only axial displacement, no radial and tangential displacement, and it is very difficult to ensure the periodicity of the screw dislocation. The current modeling methods cannot ensure the integrity of the grain boundary during the process of simultaneously constructing a screw dislocation and a grain boundary, especially a perfect coincidence-site lattice grain boundary.

[0012] In summary, for the simulation experiment of molecular dynamics, there is currently a technical problem that it is difficult to simultaneously construct a screw dislocation and a grain boundary. Summary of the Invention

[0013] In view of this, the present invention provides an atomic simulation model of dislocation-grain boundary interaction and a construction method thereof, and the main purpose is to solve the problem that it is difficult to construct a screw dislocation and a grain boundary simultaneously.

[0014] To achieve the above object, the present invention mainly provides the following technical solutions:

[0015] On the one hand, an embodiment of the present invention provides a construction method of an atomic simulation model of dislocation-grain boundary interaction, which includes the following steps:

[0016] Step of constructing a simulation box: Construct a simulation box containing a screw dislocation and perform relaxation to obtain a relaxed screw dislocation model; construct a simulation box containing a grain boundary and perform relaxation to obtain a relaxed grain boundary model;

[0017] Among them, the x-axis direction and y-axis direction of the simulation box containing the screw dislocation both maintain periodic boundary conditions; the upper surface and lower surface of the simulation box containing the screw dislocation in the z-axis direction are both set as free surfaces; the x-axis direction and y-axis direction of the simulation box containing the grain boundary both maintain periodic boundary conditions; the upper surface and lower surface of the simulation box containing the grain boundary in the z-axis direction are both set as free surfaces;

[0018] Among them, the length of the simulation box containing the screw dislocation in the z-axis direction is greater than the length of the simulation box containing the grain boundary in the z-axis direction;

[0019] Cutting step: Cut the relaxed screw dislocation model along the z-axis direction to be the same length as the z-axis direction of the relaxed grain boundary model to obtain a cut screw dislocation model;

[0020] Step of merging models: Merge the cut screw dislocation model and the relaxed grain boundary model along the y-axis direction to obtain a merged model; perform relaxation on the merged model to obtain a relaxed merged model;

[0021] Step of setting a loading module: Set the upper surface of the relaxed merged model in the z-axis direction as a loading module and the lower surface as a fixed module to obtain the atomic simulation model of dislocation-grain boundary interaction.

[0022] Preferably, the construction method of the atomic simulation model of dislocation-grain boundary interaction further includes:

[0023] Step of running the model: Read the atomic simulation model of dislocation-grain boundary interaction and apply displacement through the loading module to move the screw dislocation.

[0024] Preferably, in the step of constructing the simulation box:

[0025] In the simulation box containing screw dislocations, the number of screw dislocations is one, two, or multiple; and / or

[0026] In the simulation box containing grain boundaries, the number of grain boundaries is at least two; and / or

[0027] In the simulation box containing screw dislocations, the direction of the dislocation line is the positive x-axis direction; wherein, the Burgers vector is parallel to the dislocation line direction; and / or

[0028] The initial crystallographic orientation of the simulation box containing screw dislocations is x||[-1 0 1], y||[1 -2 1], z||[1 1 1]; the initial crystallographic orientation of the simulation box containing grain boundaries is x||[-1 0 1], y||[1 -21], z||[11 1]. For FCC (face-centered cubic) crystals, the initial crystal orientation is generally that the dislocation line is along the <1 10>{1 1 1} crystal direction family and crystal plane family, and the movement direction is generally the <1 1 2> direction. Therefore, the initial crystallographic orientation is set like this; and / or

[0029] In the simulation box containing screw dislocations, the screw dislocation is located at the middle position of the simulation box; and / or

[0030] The grain boundary is a twist grain boundary or a twin grain boundary, preferably a twist grain boundary.

[0031] Preferably, in the step of constructing the simulation box:

[0032] When constructing the simulation box containing screw dislocations, in order to ensure that the screw dislocation is on the horizontal slip plane, two Shockley partial dislocations of b / 2 are constructed at a distance of 1 - 20a0, preferably 5a0, from the horizontal slip plane; where a0 is the lattice constant; b is the Burgers vector; and / or

[0033] The length of the simulation box containing screw dislocations in the z-axis direction is 1.1 - 1.5 times, preferably 1.2 times, the length of the simulation box containing grain boundaries in the z-axis direction.

[0034] Preferably, in the step of constructing the simulation box:

[0035] In the simulation box containing grain boundaries, the distance between the grain boundary and the boundary of the simulation box in the y-axis direction is D1; where D1 is 10 - 100a0, preferably 30 - 50a0; where a0 is the lattice constant;

[0036] When the number of screw dislocations in the simulation box containing screw dislocations is one, the length of the simulation box containing screw dislocations in the y-axis direction is D2; when the number of screw dislocations in the simulation box containing screw dislocations is two, the length of the simulation box containing screw dislocations in the y-axis direction is 2×D2; where D2 is 50-200a0, preferably 70-100a0;

[0037] Among them, D1 + D2 / 2 ≥ 50a0, preferably 65-100a0.

[0038] Preferably, in the cutting step:

[0039] When cutting the relaxed screw dislocation model, it is necessary to ensure that the same length is cut on the upper and lower sides in the z-axis direction, and the z-axis direction is kept as a free surface.

[0040] Preferably, in the merging model step:

[0041] In the merged model, the distance between the screw dislocation and the grain boundary is 65-100a0, where a0 is the lattice constant.

[0042] Preferably, in the merging model step:

[0043] First, copy the cut screw dislocation model to obtain multiple cut screw dislocation models, and merge them along the y-axis direction; and / or copy the relaxed grain boundary model to obtain multiple relaxed grain boundary models, and merge them along the y-axis direction; then, merge the screw dislocation model and the grain boundary model along the y-axis direction to obtain a merged model.

[0044] Preferably, in the merging model step:

[0045] The length of the merged model in the y-axis direction is the sum of the lengths of each model in the y-axis direction before merging.

[0046] Preferably, in the cutting step, save the atomic coordinates of the cut screw dislocation model as a file recognizable by molecular simulation; and / or

[0047] In the merging model step, save the atomic coordinates of the relaxed merged model as a file recognizable by molecular simulation; and / or

[0048] In the setting loading module step, save the dislocation-grain boundary interaction atomic simulation model as a file recognizable by molecular simulation; and / or

[0049] The input file is an input file for molecular dynamics software.

[0050] On the other hand, an embodiment of the present invention provides an atomic simulation model of dislocation-grain boundary interaction. The atomic simulation model of dislocation-grain boundary interaction is constructed by the construction method of the atomic simulation model of dislocation-grain boundary interaction described in any one of the above.

[0051] Compared with the prior art, an atomic simulation model of dislocation-grain boundary interaction and its construction method of the present invention at least have the following beneficial effects:

[0052] On the one hand, an embodiment of the present invention provides a construction method of an atomic simulation model of dislocation-grain boundary interaction. First, a simulation box containing a screw dislocation is constructed and relaxed, and a simulation box containing a grain boundary is constructed and relaxed. Then, the relaxed screw dislocation model is cut along the z-axis direction to be the same length as the z-axis direction of the relaxed grain boundary model. Further, the cut screw dislocation model and the relaxed grain boundary model are merged along the y-axis direction to obtain a merged model. The merged model is relaxed. Finally, the upper surface in the z-axis direction of the relaxed merged model is set as a loading module, and the lower surface is set as a fixed module, thereby constructing an atomic simulation model of dislocation-grain boundary interaction. In addition, during the above construction process, the model containing the screw dislocation is relaxed in advance to reduce the influence of the screw dislocation displacement field, limit the influence of the screw dislocation displacement field in the initial model containing the screw dislocation, and try not to spread to the vicinity of the interface.

[0053] Furthermore, an embodiment of the present invention provides a construction method of an atomic simulation model of dislocation-grain boundary interaction. During the construction process, a suitable distance between the dislocation and the grain boundary is selected. For example, in the simulation box containing the grain boundary, the distance between the grain boundary and the boundary of the simulation box in the y-axis direction is D1. Here, D1 is 10 - 100a0, preferably 30 - 50a0, where a0 is the lattice constant. The length of the simulation box containing the screw dislocation in the y-axis direction is D2. Here, D2 is 50 - 200a0, preferably 70 - 100a0. And D1 + D2 / 2 ≥ 50a0, preferably 65 - 100a0. Here, by selecting a suitable distance between the dislocation and the grain boundary, on the basis of avoiding the displacement field of the screw dislocation from changing the structure of the grain boundary, computational resources are not wasted (if the distance is selected too small, the displacement field of the screw dislocation will change the structure of the grain boundary, and if the selected distance is too large, computational resources will be wasted).

[0054] The above description is only an overview of the technical solution of the present invention. In order to be able to understand the technical means of the present invention more clearly and implement it according to the content of the specification, the following takes the preferred embodiments of the present invention and combines with the drawings to describe in detail as follows. BRIEF DESCRIPTION OF THE DRAWINGS

[0055] Figure 1It is the topographic map of high-energy atoms and stacking fault atoms on the YZ plane of a model containing a single screw dislocation and a 101.54° (1 -2 1) twist grain boundary; among them, the energy screening method and the nearest neighbor atom method are used here to screen out the high-energy atoms (grain boundary and dislocation core) and stacking fault atoms (stacking fault near the dislocation core) in the model.

[0056] Figure 2 It is the topographic map of the screw dislocation model; among them, Figure 2 Figure a in it is the topographic map of the simulation box containing a single screw dislocation; Figure b is the topographic map of the screw dislocation model obtained after relaxation; Figure c is the topographic map of the cropped screw dislocation model; among them, Figure 2 The red in it represents high-energy atoms, and the blue represents stacking fault atoms; among them, D2 is the length of the simulation box containing the screw dislocation in the y-axis direction.

[0057] Figure 3 It is the topographic map of the grain boundary model; among them, Figure 3 Figure a in it is the topographic map of the simulation box containing the twist grain boundary; Figure b is the topographic map of the grain boundary model obtained after relaxation; among them, D1 is the distance between the grain boundary in the simulation box containing the grain boundary and the boundary of the simulation box in the y-axis direction.

[0058] Figure 4 It is the topographic map of the merged model; among them, Figure 4 Figure a in it is the topographic map of the initial state of the merged model; Figure b is the topographic map of the merged model after relaxation; Figure c is the topographic map of the merged model after setting the loading module.

[0059] Figure 5 It is the topographic map of a model containing four screw dislocations and a 101.54° (1 -2 1) twist grain boundary.

[0060] Figure 6 It is the topographic map of a model containing four screw dislocations and a 5° (1 -2 1) twist grain boundary.

[0061] Figure 7 It is the topographic map of a model containing ten screw dislocations and a 101.54° (1 -2 1) twist grain boundary.

[0062] Figure 8 It is the topographic map of a model containing four screw dislocations and a 5° (1 -1 1) twist grain boundary.

[0063] Figure 9 It is the schematic diagram of the grain boundary structure, among which, Figure 9Figure a in [reference] shows the atomic positions before and after torsion observed in the interface normal direction (black squares: before rotation, red squares: after rotation, green squares: atoms that remain unchanged before and after rotation, i.e., coincidence site lattice (CSL)), as well as the atomic positions before and after relaxation (red squares: before relaxation, blue crosses: after relaxation, red dots: coincidence site lattice after relaxation). Figure b shows the atomic positions observed in the direction perpendicular to the interface normal, i.e., the dislocation line direction. The left orientation is [-1 0 1], the right orientation is [5 4 3], and the middle is the (1 -2 1) twist grain boundary.

[0064] Figure 10 It is the stress distribution diagram of the screw dislocation - grain boundary model in Example 2.

[0065] Figure 11 It is the Nye tensor analysis diagram of the screw dislocation - grain boundary model in Example 2; among them, Figure a is the overall atomic position after splicing (observed along the dislocation line direction), Figure b is the enlarged view near the dislocation, and Figure c is the enlarged view between the dislocation and the interface. There is no irregular atomic layer between them, indicating that the splicing operation is very perfect. Among them, the blue Burger vector is [-1 -12]a / 6, and the pink Burger vector is [2 -1 -1]a / 6. The Nye tensor analysis of the large - angle grain boundary is inaccurate.

[0066] Figure 12 It is the schematic diagram of the loading analysis result of the screw dislocation - grain boundary model in Example 2; among them, blue is the single - dislocation model, and black is the four - dislocation model; among them, before the dislocation enters the interface, the model undergoes plastic deformation, and the stress - strain curve is curved; after the dislocation enters the interface, the model undergoes elastic deformation, and the stress - strain curve is a straight line.

[0067] Figure 13 It is the atomistic simulation model of the dislocation - grain boundary interaction constructed in Comparative Example 1; among them, Figure 13 Figure (a) in [reference] is the morphology diagram of high - energy atoms and stacking fault atoms on the YZ plane before relaxation of the grain boundary - dislocation model constructed by the prior art. Figure 13 Figure (b) in [reference] is the morphology diagram of high - energy atoms and stacking fault atoms on the YZ plane after relaxation.

[0068] Figure 14 It is the atomistic simulation model of the dislocation - grain boundary interaction constructed in Comparative Example 2; among them, Figure 14 Figure (a) in [reference] is the morphology diagram of high - energy atoms and stacking fault atoms on the YZ plane before relaxation of the grain boundary - dislocation model constructed by directly splicing two unrelaxed single models. Figure 14 Figure (b) in [reference] is the morphology diagram of high - energy atoms and stacking fault atoms on the YZ plane after overall relaxation.

[0069] Figure 15 It is the atomistic simulation model of the dislocation - grain boundary interaction constructed in Comparative Example 3; among them,Figure 15 Figure (a) in [reference] is a topographical map of high-energy atoms and stacking fault atoms on the YZ plane before relaxation of the grain boundary-dislocation model constructed in Comparative Example 3, where the dislocation is too close to the grain boundary. Figure 15 Figure (b) in [reference] is a topographical map of high-energy atoms and stacking fault atoms on the YZ plane after relaxation. Detailed implementation manners

[0070] To further elaborate on the technical means and effects adopted by the present invention to achieve the predetermined invention purpose, the following combines the accompanying drawings and preferred embodiments to detail the specific implementation manners, structures, features, and effects of the application according to the present invention. In the following description, different "one embodiment" or "embodiment" do not necessarily refer to the same embodiment. In addition, the specific features, structures, or characteristics in one or more embodiments can be combined in any suitable form.

[0071] A screw dislocation is a type of crystal defect, also known as a spiral dislocation. It refers to the situation where a part of the crystal slips relative to other parts, and the atomic plane spirals upward along an axis. For each revolution around the axis, the atomic plane rises by one lattice plane spacing. At the central axis is a screw-type dislocation. When there is a screw dislocation in the crystal, the original set of parallel crystal planes becomes a spiral plane with the dislocation line as the axis. If one walks around the screw dislocation loop, it is like walking on a staircase with a very small slope and no steps, moving from one crystal plane to another.

[0072] In the simulation experiment of molecular dynamics, it is very difficult to construct screw dislocations and grain boundaries simultaneously. This is because when forming a screw dislocation, there is only axial displacement, no radial and tangential displacements, and it is very difficult to ensure the periodicity of the screw dislocation. The current modeling methods cannot ensure the integrity of the grain boundary during the process of simultaneously constructing screw dislocations and grain boundaries, especially for a perfect coincidence-site lattice grain boundary. The present invention aims to simultaneously construct a perfect grain boundary while adding different numbers of screw dislocations (the number of screw dislocations can be replicated during combination), overcome the influence of the long-range displacement field of the screw dislocation on the grain boundary, and provide a perfect and reliable crystallographic model for exploring the interaction between dislocations and grain boundaries.

[0073] The technical problem to be solved by the present invention is to provide a method for conveniently and quickly constructing an atomic structure with both screw dislocations and grain boundaries, that is, an atomic simulation model of the interaction between dislocations and grain boundaries and its construction method. Based on a file given containing the atomic structure information of a crystal model, according to the requirements of the Burgers vector, dislocation position, and slip plane of the screw dislocation line to be constructed, the present invention uses a programming language to extract the atomic structure information of the crystal model in the file, automatically calculates the atomic coordinates of the crystal model containing the screw dislocation line that meets the requirements, and then outputs the data to a file in a file format recognizable by molecular dynamics software.

[0074] In view of this, the present invention provides a method for constructing a molecular dynamics grain boundary dislocation interaction model with low cost, good compatibility, high reliability, and fast operation speed. A general computer is used to achieve high-throughput model construction, and a model with almost no mutual influence between dislocation grain boundaries is stably constructed.

[0075] In addition, regarding some terms involved in the steps of the present invention, the explanations are as follows:

[0076] "Relaxation" refers to the phenomenon that the atomic arrangement inside a metal material changes slowly over time or during annealing, gradually changing into a more stable atomic arrangement structure. The specific "relaxation" method is to apply a small temperature (hypothetical temperature, temperature range is 0 - 10K, preferably 1K) and a small hypothetical initial velocity (hypothetical initial velocity to control the temperature) in the program, then cool down to find the position with the lowest residual stress, and repeat several times until the structure with the lowest energy is found. This is to obtain a balanced and uniform initial structure to prevent unreliable results in molecular dynamics simulations due to an unreasonable initial structure.

[0077] "Periodic boundary conditions" mean that the simulated structure is periodically repeated, and the current simulation box is just the smallest unit in the infinitely repeating structure. To reflect periodicity, the algorithmic processing is that when an atom runs out of one face of the periodic boundary, it is considered that the atom runs in from the opposite face.

[0078] "Free surface": Similar to the scaled boundary conditions and scaled boundary conditions with a minimum value in LAMMPS, that is, if an atom runs out of the box, the size of the box will increase accordingly to enclose the atom, and if atoms aggregate together resulting in a smaller volume, the box will also shrink accordingly, and this shrinkage is not restricted by anything.

[0079] The main technical solution of the present invention is as follows:

[0080] Steps for constructing a simulation box: Construct a simulation box containing a screw dislocation and perform relaxation to obtain a relaxed screw dislocation model; construct a simulation box containing a grain boundary and perform relaxation to obtain a relaxed grain boundary model.

[0081] It should be noted here that: In the first input file (parameters set: dislocation = 1, grain_boundary = 0), construct a simulation box containing a screw dislocation; in the second input file (parameters set: dislocation = 0, grain_boundary = 1), construct a simulation box containing a grain boundary. In the subsequent step of merging models, only need to read the constructed model and then copy and paste it to different positions in the third input file (parameters of grain boundary and dislocation do not need to be set) for merging.

[0082] Specifically, this step is as follows: Set the size of the simulation box in the input file, including the sizes in the x-axis, y-axis, and z-axis directions. Implant a screw dislocation (or two screw dislocations, or more; it should be noted that if a single dislocation is included, the dislocation core is located at the 1 / 2 position in the y-direction and 1 / 2 position in the z-direction of the simulation box. If two dislocations are included, the two dislocation cores are located at the 1 / 4 and 3 / 4 positions in the y-direction and 1 / 2 position in the z-direction) at the center of the box and perform relaxation. To ensure that the dislocation is on the horizontal slip plane, two b / 2 Shockley partial dislocations are constructed at a distance of 1 - 20a0 (preferably 5a0) from the horizontal slip plane. Here, a0 is the lattice constant; b is the Burgers vector.

[0083] Use the same method to construct a simulation box containing a grain boundary and perform relaxation. Here, it is necessary to control the grain boundary type and dislocation line length well, keep the periodic boundary conditions in the x-axis and y-axis directions, and set the upper and lower surfaces in the z-axis direction as free surfaces (i.e., scaled boundary conditions). At the same time, it is necessary to determine that the shortest distance from the grain boundary to the model boundary (along the y-axis direction) should not be less than 10a0 (to reduce the influence of the boundary conditions on the grain boundary), and the distance from the grain boundary to the boundary should not be too large (which will waste computing resources), generally less than 100a0. A suitable range here is 30 - 50a0. (That is, in the simulation box containing the grain boundary, the distance between the grain boundary and the boundary of the simulation box in the y-axis direction is D1; where D1 is 10 - 100a0, preferably 30 - 50a0; where a0 is the lattice constant).

[0084] At the same time, to eliminate the influence of the screw dislocation after subsequent model stitching, the sum of the distance from the grain boundary to the boundary and the size of the model containing the screw dislocation should not be less than 50a0 (i.e., D1 + D2 / 2 ≥ 50a0, preferably 65 - 100a0). Among them, the simulation box containing the screw dislocation needs to ensure that the z-direction is larger than the simulation model containing the grain boundary (more than 1.2 times), and the size in the y-axis direction is not less than 50a0 (to reduce the influence of the screw dislocation strain field on the grain boundary or adjacent screw dislocations), and it should not be too large (which will waste computing resources), generally less than 200a0. A more suitable distance is 70 - 100a0 (that is, the length of the simulation box containing the screw dislocation in the y-axis direction is D2; where D2 is 50 - 200a0, preferably 70 - 100a0). Save the relaxed atomic coordinates into files recognizable by molecular simulation respectively.

[0085] Preferably, in the simulation box containing the screw dislocation, the number of screw dislocations is one, two, or more.

[0086] Preferably, in the simulation box containing grain boundaries, the number of grain boundaries is at least two. To ensure the periodic boundary conditions in the y direction, the grain boundaries are constructed by rotating a part of the interval. Therefore, the constructed grain boundaries include at least two, one is the required perfect grain boundary, and the other is the grain boundary to meet the periodic conditions.

[0087] Preferably, the grain boundaries in the simulation box containing grain boundaries are twist grain boundaries or twin grain boundaries, preferably twist grain boundaries. The rotation axis of the twist grain boundary is the +y axis, rotating counterclockwise; to construct periodicity, the rotation angle here needs to meet the angle of the coincidence site lattice periodicity, and the specific angle can be any angle from 0 to 360°.

[0088] Cutting step: Cut the relaxed screw dislocation model along the z-axis direction to be the same length as the z-axis direction of the relaxed grain boundary model to obtain the cut screw dislocation model.

[0089] Specifically, in this step, read the relaxed screw dislocation model and cut it along its z-axis to be the same as the relaxed grain boundary model, where it is necessary to ensure that the same length is cut off from both sides, aiming to ensure that the dislocation is at the central position, and at the same time keep the z direction as a free surface. Save the atomic coordinates of the cut model into a file recognizable by molecular simulation.

[0090] Model merging step: Merge the cut screw dislocation model and the relaxed grain boundary model along the y-axis direction to obtain a merged model; relax the merged model to obtain a relaxed merged model.

[0091] Specifically, in this step, read the cut screw dislocation model and the relaxed grain boundary model respectively, and merge the two along the y-axis direction, ensuring that the total length after the two models are merged is the same as the sum of the two, and ensuring the periodicity in the y direction. The appropriate distance from the spliced screw dislocation to the grain boundary is 65 - 100a0; after merging, relax it, and save the atomic coordinates of the relaxed merged model into a file recognizable by molecular simulation.

[0092] Preferably, in the model merging step: First, copy the cut screw dislocation model to obtain multiple cut screw dislocation models, and merge them along the y-axis direction; and / or copy the relaxed grain boundary model to obtain multiple relaxed grain boundary models, and merge them along the y-axis direction; then, merge the screw dislocation model and the grain boundary model along the y-axis direction to obtain a merged model.

[0093] Steps for setting up the loading module: Read the relaxed combined model, set a loading module on the upper surface in the z-axis direction of the relaxed combined model, and set a fixed module on the lower surface (fix the bottom and load from the top to enable dislocation movement in the model), thus obtaining the atomic simulation model for dislocation-grain boundary interaction. Save the atomic coordinates of this model into a file recognizable by molecular simulation.

[0094] Steps for running the model: Read the constructed model and apply displacement through the loading module at the upper part of the model to make the dislocations move.

[0095] Regarding the above method, currently mainstream software such as LAMMPS can all achieve it. The input file refers to a file containing the commands that the molecular dynamics software needs to read.

[0096] In addition, it should be noted that: the modeling and simulation processes of currently mainstream software are carried out in two parts. One part of the program is specifically used to construct the model, and the other part is mainly used to run the program. Under the premise of giving a file containing the atomic structure information of the crystal model, the present invention respectively constructs simulation models containing single dislocations and twist grain boundaries. According to the input information such as Burgers vector, position of the dislocation line, slip plane, dislocation spacing, and grain boundary position, rotation axis, rotation direction, rotation angle, etc., dislocations and grain boundaries are respectively constructed, and the relaxed atomic positions are calculated by bringing in the potential function and boundary conditions, and the coordinates in the result are saved as a binary file. Then use the Fortran program to read the atomic coordinate files in the two models, and the model of the dislocation can be copied, and multiple models are spliced (combined) to construct a model containing grain boundaries and multiple dislocations. Then output the data in a file format recognizable by the molecular dynamics software.

[0097] The present invention solves the difficulty of directly constructing atomic models of any number of screw dislocations and grain boundaries with any orientation difference at specified positions inside the crystal. During the construction process, there will be no abnormal high-energy atoms, and the long-range strain field of the screw dislocations will not affect the interface structure of the grain boundaries. In addition, it can save a large amount of memory space and improve the calculation efficiency, providing a new idea for the research on the interaction between dislocations and grain boundaries by molecular dynamics.

[0098] Here, the grain boundary type mainly refers to the interface normal and twist angle of the twist grain boundary, which can be realized through the Fortran code for grain boundary construction. The Fortran language code for grain boundary construction is as follows (the following code includes information such as Burgers vector, position of the dislocation line, slip plane, dislocation spacing, grain boundary position, rotation axis, rotation direction, rotation angle, etc.):

[0099]

[0100]

[0101]

[0102] The subroutine rotmtx(r_rot, setarot, rrot): calculates the rotation matrix according to the Rodriguez formula

[0103] R = cos(θ)*I + (1 - cos(θ))n·n^T + sin(θ)n’

[0104] where n is a vector, n’ is the skew-symmetric matrix of the n vector, n^T is the transpose matrix of the n vector, θ is the rotation angle, I is the 3rd order identity matrix, and R is the rotation matrix.

[0105] Fortran code implementation: converts the rotation axis vrot and the torsional angle setarot into the rotation matrix rrot SUBROUTINE rotmtx(vrot, setarot, rrot)

[0106]

[0107]

[0108] Among them, the interface created by the rotation operation is Figure 9 illustrated by taking... as an example. The rotation axis, the rotation angle, and the relaxed atomic positions are marked in different colors respectively (see Figure 9 shown; Figure 9 is the schematic diagram of the grain boundary of 101.5° in Example 1 (observed in the y direction) and the atomic morphology diagram (observed in the x direction). The potential function used is the embedded atom method (EAM) potential function of copper proposed by Mishin in 2001. Other potential functions can also be used, such as the potential functions of Mendelev, etc. or the early (lennard-Jones) L-J potential function, newly developed machine learning potential functions, etc.

[0109] In addition, after the model is constructed, the molecular visualization software is used to display that there are no high-energy atoms and stacking fault atoms at the splicing joints of the high-energy atoms and stacking fault atoms, etc. The grain boundaries show a periodic arrangement, indicating that the splicing effect is very good and there are no defects.

[0110] Preferably, after the model is constructed, stress analysis, dislocation Nye tensor analysis, loading experiments, etc. are also carried out.

[0111] Stress analysis: The dislocation stress distribution is basically consistent with the fitting result of the elastic field. The stress field near the overall interface is small and the energy is low, which is in line with the theoretical prediction. As Figure 10 shown (from Figure 10It can be seen that no additional stress field appears at the splicing point (at ~50a0), proving that the splicing is perfectly connected without extra atoms and residual stress).

[0112] Analysis of the dislocation Nye tensor: The Burgers vector of the screw dislocation can be controlled and corresponds to the experimental results, as Figure 11 shown.

[0113] Loading experiment: Both the dislocation and grain boundary structures are consistent with the ideal state. The experimental phenomena observed during the loading process are in line with the results of elastic theory calculations, as Figure 12 shown.

[0114] The present invention will be further described below through specific embodiments as follows:

[0115] Embodiment 1

[0116] This embodiment provides a method for constructing an atomic simulation model of dislocation-grain boundary interaction, mainly including the following steps:

[0117] Step 1), in the first input file, construct a simulation box containing only one screw dislocation (see Figure 2 Figure a therein), and perform relaxation to obtain a relaxed screw dislocation model (see Figure 2 Figure b therein). Among them, during the construction process, it is necessary to ensure that the screw dislocation is located in the middle of the model (the dislocation line is along the positive x-axis, and the Burgers vector is parallel to the dislocation line direction), and the size of the simulation box is Lx×Ly×Lz = 10×80×150a0 3 ;

[0118] Among them, the potential function used to construct the simulation box of the screw dislocation is the embedded atom method (EAM) potential function of copper proposed by Mishin in 2001.

[0119] In the second input file, construct a model containing a (1 -2 1) plane rotated 101.54° clockwise around the [1 -2 1] axis (i.e., a simulation box containing a twist grain boundary, see Figure 3 Figure a therein) and perform relaxation to obtain a grain boundary model (see Figure 3 Figure b therein). Among them, the size of the box is Lx×Ly×Lz = 10×80×80a0 3 , where the distance between the grain boundaries (the distance between the left and right grain boundaries in the grain boundary model (the distance of the rotated part)) is ~190a0 (i.e., the width of the rotated part; since constructing a twist grain boundary will perform a rotation operation on a part of the box, twist grain boundaries will be formed on both sides of the rotated part, and the size of the rotated part in the y direction).

[0120] The initial crystallographic orientations of both models (the screw dislocation model and the grain boundary model) are x||[-1 0 1], y||[1 -2 1], z||[1 1 1]. The grain boundary type and the dislocation line length are controlled to maintain periodic boundary conditions in the x and y directions, and the z direction is set as the free surface. The relaxed atomic coordinates are saved in a file recognizable by molecular simulation.

[0121] In the simulation box containing the grain boundary, the distance between the grain boundary and the boundary of the simulation box in the y-axis direction is D1; where D1 is 40a0; the length of the simulation box containing the screw dislocation in the y-axis direction is D2; where D2 is 80a0; where D1 + D2 / 2 ≥ 50a0.

[0122] Step 2), read the relaxed screw dislocation model and cut it along its z-axis to be consistent with the relaxed grain boundary model, ensuring that the same length is cut off from both sides. The purpose is to ensure that the dislocation is at the center position while maintaining the z direction as the free surface. The atomic coordinates after cutting are saved in a file recognizable by molecular simulation. The cut screw dislocation model is shown in Figure 2 Figure c in

[0123] Among them, the code for cutting is as follows:

[0124] Loop through each atom in the constructed model to identify whether it is within the range to be retained. If not, delete it.

[0125]

[0126]

[0127]

[0128]

[0129] Step 3), read the cut screw dislocation model and the relaxed grain boundary model respectively, copy them, paste them into the third input file, and merge them along the y-axis direction, ensuring that the total length after the two models are merged is the same as the sum of the two, and ensuring the periodicity in the y direction. After merging, the distance from the screw dislocation to the grain boundary is 65 - 100a0. Among them, the morphology of the initial state of the merged model is shown in Figure 4 Figure a in Figure 4 Relax the merged model to obtain the relaxed merged model (the morphology is shown in Figure b in ). Save the atomic coordinates of the relaxed merged model in a file recognizable by molecular simulation.

[0130] Step 4), read the relaxed merged model, set the upper and lower surfaces in the z-axis direction as the loading module, and the set loading morphology is shown inFigure 4 As shown in Figure c in

[0131] , the atomic coordinates are saved as a file recognizable by molecular simulation. Figure 1 Shown as Figure 1 is a model containing a single screw dislocation and a 101.54° (1 -2 1) twist grain boundary. From Figure 1 it can be seen that: the single screw dislocation - large angle twist grain boundary model can be perfectly constructed.

[0132] Example 2

[0133] This example provides a method for constructing an atomic simulation model of dislocation - grain boundary interaction, which mainly includes the following steps:

[0134] Step 1), in the first input file, construct a simulation box containing only one screw dislocation and perform relaxation to obtain a relaxed screw dislocation model. Among them, during the construction process, it is necessary to ensure that the screw dislocation is located in the middle of the model (the dislocation line is along the positive x - axis direction, and the Burgers vector is parallel to the dislocation line direction), and the size of the simulation box is Lx×Ly×Lz = 10×80×150a0 3 ;

[0135] In the second input file, construct a model containing a (1 -2 1) plane rotated 101.54° clockwise around the [1 -2 1] axis twist grain boundary and perform relaxation to obtain a grain boundary model (see Figure 3 shown in Figure (b) in 3 . Among them, the distance between the grain boundaries (the distance between the left and right grain boundaries in the grain boundary model (the distance of the rotated part); since constructing a twist grain boundary will perform a rotation operation on a part of the box, twist grain boundaries will be formed on both sides of the rotated part, and the size of the rotated part in the y - direction) is ~190a0.

[0136] The initial crystallographic orientations of the two models (screw dislocation model and grain boundary - containing model) are both x||[-1 0 1], y||[1 -2 1], z||[1 1 1]. Control the grain boundary type and dislocation line length to keep the periodic boundary conditions in the x and y directions, and set the z - direction as a free surface. Save the relaxed atomic coordinates as a file recognizable by molecular simulation.

[0137] In the simulation box containing the grain boundary, the distance between the grain boundary and the boundary of the simulation box in the y-axis direction is D1; where D1 is 40a0; the length of the simulation box containing the screw dislocation in the y-axis direction is D2; where D2 is 80a0; where D1 + D2 / 2 ≥ 50a0.

[0138] Step 2), read the relaxed screw dislocation model and cut it along its z-axis to be consistent with the relaxed grain boundary model, where it is necessary to ensure that the same length is cut off from both sides. The purpose is to ensure that the dislocation is at the center position and at the same time keep the z-direction as a free surface. Save the atomic coordinates of the cut model into a file recognizable by molecular simulation.

[0139] Step 3), read the cut screw dislocation model and the relaxed grain boundary model respectively, copy them, and paste them into the third input file. Copy the cut screw dislocation model four times and splice them along the y-axis, and then merge them with the relaxed grain boundary model along the y-axis direction to ensure that the total length after the model merging is the same as the sum of the model lengths and ensure the periodicity in the y-direction. After merging, the distance from the screw dislocation to the grain boundary is 65 - 100a0.

[0140] Step 4), read the relaxed merged model, set the upper and lower surfaces in the z-axis direction as the loading module, and save the atomic coordinates into a file recognizable by molecular simulation.

[0141] Use visualization software to display high-energy atoms (partial dislocations and grain boundaries) and stacking fault atoms (dislocation decomposition), as Figure 5 shown. It can be seen from Figure 5 that the multi-screw dislocation - large-angle twist grain boundary model can be perfectly constructed.

[0142] The following analysis is carried out on the dislocation-grain boundary interaction atomic simulation model constructed in this embodiment:

[0143] Stress analysis: The dislocation stress distribution is basically consistent with the elastic field fitting result. The stress field near the overall interface is small and the energy is low, which is in line with the theoretical prediction. As Figure 10 shown (it can be seen from Figure 10 that there is no additional stress field at the splicing point (~50a), which proves that the splicing is perfect without extra atoms and residual stress).

[0144] Dislocation Nye tensor analysis: The Burgers vector of the screw dislocation can be controlled and can correspond to the experimental results, as Figure 11 shown.

[0145] Loading experiment: Both the dislocation and grain boundary structures are consistent with the ideal state. The experimental phenomena observed during the loading process are in line with the elastic theory calculation results, as Figure 12 shown.

[0146] Example 3

[0147] This embodiment provides a method for constructing an atomic simulation model of the interaction between dislocations and grain boundaries, which mainly includes the following steps:

[0148] Step 1), in the first input file, construct a simulation box containing only one screw dislocation and perform relaxation to obtain the relaxed screw dislocation model. Among them, during the construction process, it is necessary to ensure that the screw dislocation is located in the middle of the model (the dislocation line is along the positive x-axis direction, and the Burgers vector is parallel to the dislocation line direction), and the size of the simulation box is Lx×Ly×Lz = 40×80×80a0 3 ;

[0149] In the second input file, construct a model containing a (1-21) plane rotated 5° clockwise around the [1-21] axis and perform relaxation to obtain the grain boundary model (see the figure (b) shown in Figure 3 . Among them, the box size is Lx×Ly×Lz = 40×80×50a0 3 , where the distance between the grain boundaries (the distance between the left and right grain boundaries in the grain boundary model (the distance of the rotated part)) is ~80a0.

[0150] The initial crystallographic orientations of the two models (screw dislocation model and grain boundary-containing model) are both x||[-1 0 1], y||[1-2 1], z||[1 1 1]. Control the grain boundary type and dislocation line length to keep the periodic boundary conditions in the x and y directions, and set the z direction as the free surface. Save the relaxed atomic coordinates into a file recognizable by molecular simulation. The potential function used is the embedded atom method (EAM) potential function of copper proposed by Mishin in 2001.

[0151] In the simulation box containing the grain boundary, the distance between the grain boundary and the boundary of the simulation box in the y-axis direction is D1; among them, D1 is 40a0; the length of the simulation box containing the screw dislocation in the y-axis direction is D2; among them, D2 is 80a0; among them, D1 + D2 / 2 ≥ 50a0.

[0152] Step 2), read the relaxed screw dislocation model and cut it along its z-axis to be consistent with the relaxed grain boundary model, where it is necessary to ensure that the same length is cut off from both sides. The purpose is to ensure that the dislocation is in the central position and at the same time keep the z direction as the free surface. Save the atomic coordinates after cutting into a file recognizable by molecular simulation.

[0153] Step 3), read the cropped screw dislocation model and the relaxed grain boundary model respectively, copy them, and paste them into the third input file. Copy the cropped screw dislocation model four times and splice them along the y-axis, and then merge them with the relaxed grain boundary model along the y-axis direction (first splice them into two dislocation-containing models, then place the grain boundary-containing model in the middle and the two dislocation-containing models on both sides to construct the overall model. First, copy the dislocation-containing model four times and place them in the four intervals of 0 - 80a0, 80 - 160a0, 320 - 400a0, and 400 - 480a0 respectively, and then place the grain boundary-containing model in the interval of 160a0 - 320a0), ensure that the total length after model merging is the same as the sum of the model lengths, and ensure the periodicity in the y direction. After merging, the distance from the screw dislocation to the grain boundary is 65 - 100a0.

[0154] Step 4), read the relaxed merged model, set the upper and lower surfaces in the z-axis direction as the loading modules, and save the atomic coordinates into a file recognizable by molecular simulation.

[0155] Use visualization software to display high-energy atoms (partial dislocations and grain boundaries) and stacking fault atoms (dislocation decomposition), as Figure 6 shown. It can be seen from Figure 6 that multiple screw dislocations - small-angle twist grain boundaries on the free surface can be perfectly constructed, and stacking fault atoms and high-energy atoms on the interface are not shown here.

[0156] Example 4

[0157] This example provides a method for constructing an atomic simulation model of dislocation-grain boundary interaction, which mainly includes the following steps:

[0158] Step 1), in the first input file, construct a simulation box containing only one screw dislocation and relax it to obtain the relaxed screw dislocation model. Among them, during the construction process, it is necessary to ensure that the screw dislocation is located in the middle of the model (the dislocation line is along the positive x-axis direction, and the Burgers vector is parallel to the dislocation line direction), and the size of the simulation box is Lx×Ly×Lz = 10×80×80a0 3 ;

[0159] Construct a model containing a (1 -2 1) plane rotated 101.5° clockwise around the [1 -2 1] axis twist grain boundary in the second input file and relax it to obtain the grain boundary model (see Figure 3 Figure (b)). Among them, the box size is Lx×Ly×Lz = 10×80×50a0 3 , where the distance between the grain boundaries (the distance between the left and right grain boundaries in the grain boundary model (the distance of the rotated part)) is ~80a0.

[0160] The initial crystallographic orientations of the two models (the screw dislocation model and the grain boundary model) are both x||[-1 0 1], y||[1 -2 1], z||[1 1 1] (for FCC (face-centered cubic) crystals, the initial crystal orientation generally has the dislocation line along the <1 1 0> crystallographic direction family of the {1 1 1} crystal plane family, and the movement direction is generally the <1 1 2> direction, so the initial crystallographic orientation is set like this), and the grain boundary type and dislocation line length are controlled to keep the periodic boundary conditions in the x and y directions, and the z direction is set as the free surface. The relaxed atomic coordinates are saved as a file recognizable by molecular simulation. The potential function used is the embedded atom method (EAM) potential function of copper proposed by Mishin in 2001.

[0161] In the simulation box containing the grain boundary, the distance between the grain boundary and the boundary of the simulation box in the y-axis direction is D1; where D1 is 40a0; the length of the simulation box containing the screw dislocation in the y-axis direction is D2; where D2 is 80a0; where D1 + D2 / 2 ≥ 50a0.

[0162] Step 2), read the relaxed screw dislocation model and cut it along its z-axis to be the same as the relaxed grain boundary model, where it is necessary to ensure that the same length is cut off from both sides, the purpose is to ensure that the dislocation is in the center position, and at the same time keep the z direction as the free surface. The cut atomic coordinates are saved as a file recognizable by molecular simulation.

[0163] Step 3), read the cut screw dislocation model and the relaxed grain boundary model respectively, copy them, and paste them in the third input file. Copy the cut screw dislocation model ten times and splice them along the y-axis, and then merge them with the relaxed grain boundary model along the y-axis direction (here, splicing is to copy ten first. The position of the first model containing the screw dislocation in the y direction is 0 - y0, and the copied models are placed at y0 - 2y0, 2y0 - 3y0, 3y0 - 4y0, until 7y0 - 8y0. In addition, to ensure periodicity, the other two models containing dislocations are placed at 10y0 - 11y0, 11y0 - 12y0. Where y0 represents the size of the model containing the dislocation in the y direction, which is 80a0 here), ensure that the total length after the models are merged is the same as the sum of the model lengths, and ensure the periodicity in the y direction. After merging, the distance from the screw dislocation to the grain boundary is 65 - 100a0.

[0164] Step 4), read the relaxed merged model, set the upper and lower surfaces in the z-axis direction as the loading module, and save the atomic coordinates as a file recognizable by molecular simulation.

[0165] Use visualization software to display high-energy atoms (partial dislocations and grain boundaries) and stacking fault atoms (dislocation decomposition), as Figure 7 shown. From Figure 7It can be seen that: The more screw dislocation-large angle twist grain boundary model can be perfectly constructed.

[0166] Example 5

[0167] This embodiment provides a method for constructing an atomic simulation model of dislocation-grain boundary interaction, which mainly includes the following steps:

[0168] Step 1), in the first input file, construct a simulation box containing only one screw dislocation and perform relaxation to obtain the relaxed screw dislocation model. Among them, during the construction process, it is necessary to ensure that the screw dislocation is located in the middle of the model (the dislocation line is along the positive x-axis, and the Burgers vector is parallel to the dislocation line direction), and the size of the simulation box is Lx×Ly×Lz = 40×80×80a0 3 ;

[0169] In the second input file, construct a model containing a (1 -1 1) plane rotated clockwise by 5° around the [1 -1 1] axis twist grain boundary and perform relaxation to obtain the grain boundary model (see Figure 3 Figure (b) shown). Among them, the box size is Lx×Ly×Lz = 40×80×50a0 3 , where the distance between the grain boundaries (the distance between the left and right grain boundaries in the grain boundary model (the distance of the rotated part)) is ~30a0.

[0170] The initial crystallographic orientations of the two models (screw dislocation model and grain boundary-containing model) are both x||[-1 0 1], y||[1 -2 1], z||[1 1 1], and control the grain boundary type and dislocation line length to keep the periodic boundary conditions in the x and y directions, and set the z direction as the free surface, and save the relaxed atomic coordinates into a file recognizable by molecular simulation. The potential function used is the embedded atom potential (EAM) potential function of copper proposed by Mishin in 2001.

[0171] In the simulation box containing the grain boundary, the distance between the grain boundary and the boundary of the simulation box in the y-axis direction is D1; among them, D1 is 40a0; the length of the simulation box containing the screw dislocation in the y-axis direction is D2; among them, D2 is 80a0; among them, D1 + D2 / 2 ≥ 50a0.

[0172] Step 2), read the relaxed screw dislocation model and cut it along its z-axis to be consistent with the relaxed grain boundary model, where it is necessary to ensure that the same length is cut off from both sides, the purpose is to ensure that the dislocation is in the central position, and at the same time keep the z direction as the free surface, and save the atomic coordinates after cutting into a file recognizable by molecular simulation.

[0173] Step 3), read the cropped screw dislocation model and the relaxed grain boundary model respectively, copy them, and paste them into the third input file. Copy the cropped screw dislocation model four times and splice them along the y-axis, and then merge them with the relaxed grain boundary model along the y-axis direction (the crystal plane index in this embodiment is (1 -1 1), so it can only be placed obliquely. The construction method is also to first copy the model containing dislocations four times and place them in the four intervals of 0-80a0, 80-160a0, 320-400a0, and 400-480a0 respectively, and then place the model containing the grain boundary in the interval of 160a0-320a0). Ensure that the total length after model merging is the same as the sum of the model lengths, and ensure the periodicity in the y direction. After merging, the appropriate distance from the screw dislocation to the grain boundary is 65-100a0.

[0174] Step 4), read the relaxed merged model, set the upper and lower surfaces in the z-axis direction as the loading module, and save the atomic coordinates into a file recognizable by molecular simulation.

[0175] Use visualization software to display high-energy atoms (partial dislocations and grain boundaries) and stacking fault atoms (dislocation decomposition), as Figure 8 shown. From Figure 8 it can be seen that: Multiple screw dislocations on the free surface - small-angle twist grain boundaries with arbitrary interface orientations can be constructed. The complete process of constructing the model of stacking fault atoms and high-energy atoms on the interface is not shown here.

[0176] Comparative Example 1

[0177] Comparative Example 1 provides a construction method for an atomic simulation model of dislocation-grain boundary interaction in the prior art, which mainly includes the following steps:

[0178] In the input file, directly construct a simulation box containing 10 screw dislocations and a twist grain boundary, and perform relaxation to obtain the relaxed screw dislocation model. Among them, during the construction process, it is necessary to ensure that 10 screw dislocations are inserted at equal intervals (20a0) starting from the left side of the y-axis of the model (the dislocation line is along the positive x-axis direction, and the Burgers vector is parallel to the dislocation line direction). The size of the simulation box is Lx×Ly×Lz = 4×222×200a0 3 ; The constructed grain boundary is a model of a (1 -2 1) plane located at 200a0 in the y-axis direction rotated 101.5° clockwise around the [1 -2 1] axis and perform relaxation to obtain the overall screw dislocation - grain boundary model (see Figure 13(as shown in Figure (a)). The initial grain boundary orientation of the entire model (simultaneously constructing a model containing screw dislocations and grain boundaries) is x||[-1 0 1], y||[1 -2 1], z||[1 1 1]. Control the grain boundary type and dislocation line length to maintain periodic boundary conditions in the x and y directions, and set the z direction as the free surface. Save the relaxed atomic coordinates as a file recognizable by molecular simulation. The potential function used is the embedded atom method (EAM) potential function for copper proposed by Mishin in 2001.

[0179] Use visualization software to display high-energy atoms (partial dislocations and grain boundaries) and stacking fault atoms (dislocation dissociation), as Figure 13 shown in Figure (b). From Figure 13 Figure (b), it can be seen that: after relaxation, the number of dislocations in the model changes from 10 to 8, and two dislocations disappear; in addition, the grain boundary structure also changes, with an increase in high-energy atoms and more stacking fault atoms appearing on the interface.

[0180] Comparative Example 2

[0181] Comparative Example 2 provides a method for constructing an atomic simulation model of dislocation-grain boundary interaction, mainly including the following steps:

[0182] Step 1), in the input file, construct a simulation box containing only one screw dislocation without relaxation to obtain an initial screw dislocation model. Among them, during the construction process, it is necessary to ensure that the screw dislocation is located in the middle of the model (the dislocation line is along the positive x-axis, and the Burgers vector is parallel to the dislocation line direction). The size of the simulation box is Lx×Ly×Lz = 4×100×100a0 3 ;

[0183] Construct a model containing a (1 -2 1) plane rotated 101.5° clockwise around the [1 -2 1] axis of the twist grain boundary without relaxation to obtain a grain boundary model. Among them, the size of the box is Lx×Ly×Lz = 4×100×100a0 3 , where the distance between grain boundaries is ~20a0.

[0184] The initial grain boundary orientation of the two models (screw dislocation model and grain boundary-containing model) is x||[-1 0 1], y||[1 -2 1], z||[1 1 1]. Control the grain boundary type and dislocation line length to maintain periodic boundary conditions in the x and y directions, and set the z direction as the free surface. Save the non-relaxed atomic coordinates as a file recognizable by molecular simulation. The potential function used is the embedded atom method (EAM) potential function for copper proposed by Mishin in 2001.

[0185] In a simulation box containing a grain boundary, the distance between the grain boundary and the boundary of the simulation box in the y-axis direction is D1; where D1 is 40a0; the length of the simulation box containing a screw dislocation in the y-axis direction is D2; where D2 is 100a0; where D1 + D2 / 2 ≥ 50a0.

[0186] Step 2), respectively read the unrelaxed screw dislocation model and the unrelaxed grain boundary model, copy the unrelaxed screw dislocation model twice and place them in the intervals of 0 - 100a0 and 200 - 300a0 respectively, and then place the unrelaxed grain boundary model in the interval of 100 - 200a0 in the y-axis direction and merge them for relaxation, ensuring that the total length after model merging is the same as the sum of the model lengths, and ensuring the periodicity in the y direction. After merging, the appropriate distance from the screw dislocation to the grain boundary is 65 - 100a0.

[0187] Use visualization software to display high-energy atoms (partial dislocations and grain boundaries) and stacking fault atoms (dislocation decomposition). Before relaxation after overall splicing, as shown in Figure 14 Figure (a) of. After relaxation after overall splicing, as shown in Figure 14 Figure (b) of. It can be seen that relaxing after splicing the unrelaxed model will result in residual high-energy atoms and stacking fault atoms that should not exist at the interface of the original spliced model.

[0188] Comparative Example 3

[0189] Comparative Example 3 provides a method for constructing an atomic simulation model of dislocation-grain boundary interaction, which mainly includes the following steps:

[0190] In the input file, directly construct a simulation box containing 2 screw dislocations and a twist grain boundary, and perform relaxation to obtain a relaxed screw dislocation model. Among them, during the construction process, the 2 screw dislocations are respectively placed at positions ~10a0 away from the model boundary on the left and right sides of the model (the dislocation line is along the positive x-axis direction, and the Burgers vector is parallel to the dislocation line direction), and the size of the simulation box is Lx×Ly×Lz = 4×40×200a0 3 ; where the distance between the grain boundaries is ~4a0. Construct a model of a (1 - 2 10) plane rotated 101.5° clockwise around the [1 -2 1] axis as a twist grain boundary and perform relaxation to obtain an overall screw dislocation - grain boundary model (see Figure 15as shown in Figure (a) therein. The initial grain boundary orientation of the entire model (simultaneously constructing a model containing screw dislocations and grain boundaries) is x||[-1 0 1], y||[1 -2 1], z||[1 1 1]. The grain boundary type and dislocation line length are controlled to maintain periodic boundary conditions in the x and y directions, and the z direction is set as a free surface. The relaxed atomic coordinates are saved as a file recognizable by molecular simulation. The potential function used is the embedded atom method (EAM) potential function of copper proposed by Mishin in 2001.

[0191] Visualization software is used to display high-energy atoms (partial dislocations and grain boundaries) and stacking fault atoms (dislocation dissociation). Before relaxation, it is as shown in Figure 15 Figure (a) therein. After relaxation, as can be seen from Figure 15 Figure (b) therein: Since the screw dislocation is too close to the twist interface (D1 + D2 / 2 ≈ 6a0 < 50a0), the dislocation disappears after relaxation and may be absorbed by the interface. More high-energy atoms and irregular stacking fault atoms also appear in the interface structure.

[0192] As described above, it is only a preferred embodiment of the present invention, and there is no limitation in any form to the present invention. Any simple modification, equivalent change, and modification made to the above embodiments according to the technical essence of the present invention still fall within the scope of the technical solution of the present invention.

Claims

1. A method for constructing an atomic simulation model of dislocation grain boundary interaction, characterized in that: It includes the following steps: Steps for constructing a simulation box: construct a simulation box containing a screw dislocation and perform relaxation to obtain a relaxed screw dislocation model; construct a simulation box containing a grain boundary and perform relaxation to obtain a relaxed grain boundary model; Wherein, the x-axis direction and the y-axis direction of the simulation box containing screw dislocations both maintain periodic boundary conditions; the upper surface and the lower surface of the simulation box containing screw dislocations in the z-axis direction are both set as free surfaces; the x-axis direction and the y-axis direction of the simulation box containing grain boundaries both maintain periodic boundary conditions; the upper surface and the lower surface of the simulation box containing grain boundaries in the z-axis direction are both set as free surfaces; Wherein, the length of the simulation box containing screw dislocation in the z-axis direction is greater than the length of the simulation box containing grain boundary in the z-axis direction; A cutting step: cutting the relaxed screw dislocation model along the z-axis direction to a length consistent with the z-axis length of the relaxed grain boundary model to obtain a cut screw dislocation model; Merging model step: merging the trimmed screw dislocation model and the relaxed grain boundary model along the y-axis direction to obtain a merged model; relaxing the merged model to obtain a relaxed merged model; The step of setting a loading module: setting a loading module on the upper surface of the relaxed merged model in the z-axis direction and a fixing module on the lower surface to obtain the dislocation grain boundary interaction atomic simulation model.

2. The method for constructing the atomic simulation model of dislocation grain boundary interaction according to claim 1, characterized in that: The method for constructing the dislocation grain boundary interaction atomic simulation model further includes: The step of running the model is as follows: reading the dislocation grain boundary interaction atomic simulation model, and applying displacement through the loading module to move the screw dislocation.

3. The method for constructing an atomic simulation model of dislocation grain boundary interaction according to claim 1 or 2, characterized in that: In the steps of building the simulation box: In the simulation box containing screw dislocations, the number of screw dislocations is one, two or more; and / or In the simulation box containing grain boundaries, the number of grain boundaries is at least two; and / or In the simulation box containing the screw dislocation, the dislocation line direction is the positive direction of the x-axis; wherein the Burgers vector is parallel to the dislocation line direction; and / or The initial grain boundary orientation of the simulation box containing screw dislocations is x||[-1 0 1], y||[1-2 1], z||[1 11]; the initial grain boundary orientation of the simulation box containing grain boundaries is x||[-1 0 1], y||[1-21], z||[1 1 1]; and / or In the simulation box containing the screw dislocation, the screw dislocation is located in the middle of the simulation box; and / or The grain boundary is a twist grain boundary or a twin boundary, preferably a twist grain boundary.

4. The method for constructing an atomic simulation model of dislocation grain boundary interaction according to any one of claims 1 to 3, characterized in that: In the steps of building the simulation box: When constructing a simulation box containing a screw dislocation, in order to ensure that the screw dislocation is on the horizontal slip plane, two b / 2 Shockley partial dislocations are constructed at a distance of 1-20a0, preferably 5a0, from the horizontal slip plane; wherein a0 is the lattice constant; b is the Burgers vector; and / or The length of the simulation box containing screw dislocations in the z-axis direction is 1.1-1.5 times, preferably 1.2 times, the length of the simulation box containing grain boundaries in the z-axis direction.

5. The method for constructing an atomic simulation model of dislocation grain boundary interaction according to any one of claims 1 to 4, characterized in that: In the steps of building the simulation box: In the simulation box containing the grain boundary, the distance between the grain boundary and the boundary of the simulation box in the y-axis direction is D1; ​​wherein D1 is 10 to 100a0, preferably 30 to 50a0; wherein a0 is a lattice constant; When the number of screw dislocations in the simulation box containing screw dislocations is one, the length of the simulation box containing screw dislocations in the y-axis direction is D2; when the number of screw dislocations in the simulation box containing screw dislocations is two, the length of the simulation box containing screw dislocations in the y-axis direction is 2×D2; wherein D2 is 50 to 200a0, preferably 70 to 100a0; Among them, D1+D2 / 2≥50a0, preferably 65~100a0.

6. The method for constructing an atomic simulation model of dislocation grain boundary interaction according to any one of claims 1 to 5, characterized in that: In the cropping step: When cutting the relaxed screw dislocation model, it is necessary to ensure that the upper and lower sides in the z-axis direction are cut to the same length and keep the z-axis direction as a free surface.

7. The method for constructing an atomic simulation model of dislocation grain boundary interaction according to any one of claims 1 to 6, characterized in that: In the Merge Models step: In the merged model, the distance between the screw dislocation and the grain boundary is 65-100a0, where a0 is the lattice constant.

8. The method for constructing an atomic simulation model of dislocation grain boundary interaction according to any one of claims 1 to 7, characterized in that: In the Merge Models step: First, the trimmed screw dislocation model is copied to obtain multiple trimmed screw dislocation models, and the models are merged along the y-axis direction; and / or the relaxed grain boundary model is copied to obtain multiple relaxed grain boundary models, and the models are merged along the y-axis direction; then, the screw dislocation model and the grain boundary model are merged along the y-axis direction to obtain a merged model.

9. The method for constructing an atomic simulation model of dislocation grain boundary interaction according to any one of claims 1 to 8, characterized in that: In the Merge Models step: The length of the merged model on the y-axis is the sum of the lengths of each model on the y-axis before the merge.

10. The method for constructing an atomic simulation model of dislocation grain boundary interaction according to any one of claims 1 to 9, characterized in that: In the trimming step, the atomic coordinates of the trimmed screw dislocation model are saved as a file recognizable by molecular simulation; and / or In the model merging step, the atomic coordinates of the relaxed merged model are saved as a file recognizable by molecular simulation; and / or In the step of setting the loading module, the dislocation grain boundary interaction atomic simulation model is saved as a file recognizable by molecular simulation; and / or The input file is an input file of molecular dynamics software.

11. An atomic simulation model of dislocation grain boundary interaction, characterized in that: The dislocation grain boundary interaction atomic simulation model is constructed by the method for constructing the dislocation grain boundary interaction atomic simulation model according to any one of claims 1-10.

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