A TiAl alloy crystal plasticity finite element modeling method and electronic device

Abstract

The present invention provides a TiAl alloy crystal plasticity finite element modeling method and electronic equipment, which uses electron backscatter diffraction technology to obtain grain data of a given material sample, obtains grain material properties based on electron backscatter diffraction data analysis software and according to the grain data, and establishes a grain geometry model based on finite element analysis software. The grain geometry model is assigned grain material properties, and an indentation finite element model is constructed. The crystal plasticity constitutive relationship information in a pre-written subroutine is extracted and coupled to the indentation finite element model to obtain a crystal plasticity finite element model. In this solution, on the one hand, the modeling process is simple and convenient, and on the other hand, the real performance of the material and the constitutive relationship are taken into account, which is helpful to accurately predict the mechanical properties of the crystal and thus achieve microstructure optimization.

Description

Technical Field

[0001] The invention relates to the technical field of modeling, and in particular to a TiAl alloy crystal plastic finite element modeling method and electronic equipment. Background Art

[0002] TiAl alloy is regarded as an advanced high-temperature structural material with great application potential in the range of 700~1000℃ due to its excellent comprehensive properties such as low density (about 4.0g / cm³), high specific strength, high specific modulus, good high-temperature oxidation resistance and creep resistance. Although it has been initially applied in fields such as aeroengines, such as the preparation of low-pressure turbine blades for GEnx and GE9X aeroengines, its widespread application still faces challenges such as room temperature brittleness, difficulty in improving high-temperature strength and poor forming performance. TiAl alloy is mainly composed of Ti and Al intermetallic compounds, and its density is only half that of nickel-based high-temperature alloys. It has good application prospects in the field of aeroengines. However, the high brittleness of TiAl alloy requires the use of multiple processes in the manufacturing process, and all require a certain degree of mechanical processing to meet the design requirements. The surface state after mechanical processing has a great influence on the durability and mechanical properties of parts under long-term high-temperature service conditions. The surface treatment of TiAl alloy faces two main difficulties: first, the brittleness of the alloy causes conventional surface strengthening treatment to easily induce cracks and reduce fatigue life; second, the surface processing process will increase the surface roughness of the metal, and the rough surface is prone to crack initiation. These irregular crack initiation results in large differences in the failure behavior of parts, which is not conducive to part design optimization and reliability prediction. Therefore, it is of great practical value to provide a composite processing method that can improve the consistency of mechanical properties of TiAl alloy parts. In addition, TiAl alloy accounts for one-third of the weight of modern aircraft engines and is the second largest engine material after nickel-based high-temperature alloys. The use of TiAl alloy to replace nickel-based high-temperature alloys can significantly reduce weight while ensuring specific strength and specific stiffness at high temperatures, which has great advantages in the design and manufacture of lightweight structural parts in industries such as aerospace and automobiles. However, the room temperature brittleness and difficulty in deformation processing of TiAl alloys make it difficult to ensure the service life and service performance of the workpiece during the processing process. Therefore, in-depth research on TiAl alloys, especially how to improve their mechanical properties and processing performance through advanced processing technology, has become an important topic in the current field of materials science and engineering.

[0003] At the mesoscopic scale, the plastic deformation modes of metals include slip, twinning, grain boundary slip, etc. Crystal Plasticity Finite Element Method (CPFEM) is a method based on the crystal plasticity theory coupled with the finite element method to study the plastic behavior of crystals. Crystal plasticity theory combines traditional plastic mechanics theory with crystallographic micro-deformation. Its core idea is to introduce internal variables closely related to crystal defects or deformation (such as dislocation density, irradiation defect density, etc.) to quantify the microscopic deformation of crystals into plastic strain in traditional plasticity theory, thereby establishing the relationship between microscopic deformation mechanism and macroscopic mechanical behavior. Crystal plasticity theory can describe the evolution of multiple deformation mechanisms (slip, twinning and phase transformation, etc.) at the mesoscopic scale, and is the link between the macroscopic mechanical behavior and microscopic mechanism of crystal materials. In addition, the crystal plasticity finite element method formed by combining with powerful commercial finite element software makes the prediction and simulation of the plastic behavior of crystal materials in complex deformation processes a reality, and has been widely used in engineering practice. Therefore, it is of great theoretical significance and engineering application value to establish a crystal plastic finite element model of TiAl alloy, reveal its plastic deformation mechanism from the root, and then fully optimize and rationally utilize the mechanical properties of TiAl alloy. The plastic deformation of TiAl alloy is achieved through the complex interaction of dislocations and twin boundaries. The mechanical behavior of different phases, grains, and grain boundaries of TiAl alloys is tested by experimental methods, which has the disadvantages of high sample preparation cost and long cycle. The establishment of a theoretical model that can intuitively describe the mechanical properties can just make up for the shortcomings of the experimental method. Therefore, there is an urgent need for a constitutive model that can accurately predict the mechanical properties of TiAl alloys to achieve the reasonable optimization of the mechanical properties of TiAl alloys and guide the design of their microstructures.

[0004] In the prior art, there are related technologies that can realize the establishment and simulation of crystal plasticity constitutive models. However, most of the related technologies in the prior art have certain defects. For example, there may be defects such as requiring operators to have strong programming skills, low degree of restoration of real grains, and the need to switch between multiple software and scripts, resulting in a more complicated program. Therefore, how to realize a simple and convenient crystal plasticity modeling method that conforms to the real performance of the material is a technical problem that needs to be solved urgently. Summary of the invention

[0005] The objects of the present invention include, for example, providing a TiAl alloy crystal plasticity finite element modeling method and electronic equipment, which can help to accurately predict the mechanical properties of the crystal and thus achieve microstructure optimization.

[0006] The embodiments of the present invention can be implemented as follows:

[0007] In a first aspect, the present invention provides a TiAl alloy crystal plasticity finite element modeling method, the method comprising:

[0008] Using electron backscatter diffraction technology to obtain grain data of a given material sample, wherein the given material sample is a TiAl alloy material sample;

[0009] Obtaining grain material properties based on the electron backscatter diffraction data analysis software and the grain data;

[0010] Establishing a grain geometry model based on finite element analysis software and according to the grain data;

[0011] Assigning the grain material properties to the grain geometric model, and constructing an indentation finite element model;

[0012] Extracting crystal plasticity constitutive relationship information from a pre-written subroutine, and coupling the crystal plasticity constitutive relationship information to the indentation finite element model to obtain a crystal plasticity finite element model;

[0013] The TiAl alloy includes a γ-TiAl phase and an α2-Ti3Al phase, the slip system in the γ-TiAl phase includes a normal slip system, a super slip system and a twin system, the slip system in the α2-Ti3Al phase includes a basal slip system, a cylindrical slip system and a conical slip system, and the step of extracting the crystal plastic constitutive relationship information in the pre-written subroutine includes:

[0014] The initial orientation of the grains is selected in advance based on the dislocation slip deformation mechanism, the slip system in the γ-TiAl phase and the α2-Ti3Al phase, a γ-TiAl crystal plasticity finite element constitutive relationship model that comprehensively considers ordinary dislocations, super dislocations and twinning is established, and a α2-Ti3Al crystal plasticity finite element constitutive relationship model is established, the γ-TiAl crystal plasticity finite element constitutive relationship model and the α2-Ti3Al crystal plasticity finite element constitutive relationship model are written into a subroutine, and the crystal plasticity constitutive relationship information is obtained by extracting the subroutine.

[0015] In an optional embodiment, the step of assigning the grain material properties to the grain geometric model and constructing an indentation finite element model comprises:

[0016] Assigning the grain material properties to the grain geometric model, and setting analysis steps and boundary conditions, wherein one analysis step includes a plurality of incremental steps;

[0017] Meshing the grain geometric model to obtain a plurality of meshes;

[0018] The indentation finite element model is obtained based on the meshed grain geometry model.

[0019] In an optional embodiment, the step of meshing the grain geometric model to obtain a plurality of meshes includes:

[0020] Meshing the grain geometric model using an eight-node linear hexahedral mesh to obtain a plurality of meshes;

[0021] A local boundary region in the grain geometric model is delineated, and meshes in the local boundary region are encrypted.

[0022] In an optional embodiment, the step of coupling the crystal plasticity constitutive relationship information to the indentation finite element model to obtain a crystal plasticity finite element model comprises:

[0023] Based on the crystal plasticity constitutive relation information, Taylor cumulative shear strains on all slip and twin systems are obtained, and based on the Taylor cumulative shear strains, cumulative twin volume fractions are calculated;

[0024] Taking each grid in the indentation finite element model as a unit integration point, and calculating the cumulative twin volume fraction of all twin variants in each unit integration point according to the number of twin systems turned on;

[0025] After each incremental step, the accumulated twin volume fraction is compared with the dynamic threshold. If the accumulated twin volume fraction is greater than the dynamic threshold, the grain material information of the corresponding unit integration point is updated until the crystal plasticity finite element model is obtained after all incremental steps.

[0026] In an optional embodiment, the step of updating the grain material information of the corresponding unit integration point includes:

[0027] Obtain the twin surface normal vector of the dominant twin system of the corresponding unit integration point;

[0028] Updated grain orientation information is obtained based on the twin plane normal vector and the second-order unit vector.

[0029] In an optional implementation, the dynamic threshold is obtained by:

[0030] Obtain the minimum twin volume fraction for orientation rotation and the evolution parameters of the twin volume fraction during plastic deformation;

[0031] A dynamic threshold is obtained based on the minimum twin volume fraction, the evolution parameter and the cumulative twin volume fraction of the current incremental step.

[0032] In an optional embodiment, the grain data includes phase information and grain information of the given material sample, and the grain information includes surface Euler angles and grain morphology.

[0033] In an optional embodiment, the method further comprises:

[0034] Simulating the crystal plasticity finite element model to obtain simulation result data of nanoindentation points of a single grain and nanoindentation points at grain boundaries, and obtaining experimental result data of nanoindentation points of a single grain and nanoindentation points at grain boundaries;

[0035] The simulation result data and the experimental result data are outputted in a graphical manner based on visualization technology.

[0036] In a second aspect, the present invention provides an electronic device, comprising a memory and a processor, wherein the memory stores a computer program that can be run on the processor, and when the processor executes the computer program, the steps of the method described in any of the aforementioned implementation modes are implemented.

[0037] The beneficial effects of the embodiments of the present invention include, for example:

[0038] The present invention provides a TiAl alloy crystal plasticity finite element modeling method and electronic equipment, which uses electron backscatter diffraction technology to obtain grain data of a given material sample, obtains grain material properties based on electron backscatter diffraction data analysis software and according to the grain data, and establishes a grain geometry model based on finite element analysis software. The grain geometry model is assigned grain material properties, and an indentation finite element model is constructed. The crystal plasticity constitutive relationship information in a pre-written subroutine is extracted and coupled to the indentation finite element model to obtain a crystal plasticity finite element model. In this solution, on the one hand, the modeling process is simple and convenient, and on the other hand, the real performance of the material and the constitutive relationship are taken into account, which is helpful to accurately predict the mechanical properties of the crystal and thus achieve microstructure optimization. BRIEF DESCRIPTION OF THE DRAWINGS

[0039] In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings required for use in the embodiments are briefly introduced below. It should be understood that the following drawings only show certain embodiments of the present invention and therefore should not be regarded as limiting the scope. For ordinary technicians in this field, other related drawings can be obtained based on these drawings without creative work.

[0040] Figure 1 A flow chart of a TiAl alloy crystal plasticity finite element modeling method provided in an embodiment of the present invention;

[0041] Figure 2 for Figure 1 A flowchart of the sub-steps included in S14;

[0042] Figure 3 It is a schematic diagram of a three-dimensional model of a single crystal model;

[0043] Figure 4 It is the top view of the single crystal model;

[0044] Figure 5 It is the top view of the twin crystal model;

[0045] Figure 6 Schematic diagram of four sets of indentation experiments performed on a series of treated material surfaces;

[0046] Figure 7 Schematic diagram of the indentation point in the third group of indentation experiments, where (a) is the metallographic image of the indentation point, (b) is the grain boundary image of electron backscatter diffraction, (c) is the phase image, and (d) is the inverse pole image;

[0047] Figure 8 The AFM images of the indentation points in the third group of indentation experiments, wherein (a) is the AFM images of the three indentation points, (b) is the AFM image of the indentation point 31, (c) is the AFM image of the indentation point 32, and (d) is the AFM image of the indentation point 33;

[0048] Fig. 9 for Figure 1 A flowchart of the sub-steps included in S15;

[0049] Fig.10 This is the stress cloud diagram at the indentation point 31 in the third group of indentation experiments;

[0050] Fig.11 This is the surface accumulation diagram under the indentation point 31 example in the third group of indentation experiments;

[0051] Fig.12 It is a comparison diagram of load displacement curves under the example of indentation point 31;

[0052] Fig.13 A comparison diagram of the stacking height distance curve on the upper side of the indentation point in the example of indentation point 31;

[0053] Fig.14 It is a comparison diagram of the stacking height distance curve at the lower side of the indentation point in the example of indentation point 31;

[0054] Fig.15 This is the stress cloud diagram at the indentation point 32 in the third group of indentation experiments;

[0055] Fig.16 It is the surface accumulation diagram under the indentation point 32 example in the third group of indentation experiments;

[0056] Fig.17 It is a comparison diagram of load displacement curves under the example of indentation point 32;

[0057] Fig.18It is a comparison diagram of the stacking height distance curve on the left side of the indentation point in the example of indentation point 32;

[0058] Fig.19 It is a comparison diagram of the stacking height distance curve on the right side of the indentation point in the example of indentation point 32;

[0059] Fig. 20 This is the stress cloud diagram at the indentation point 33 in the third group of indentation experiments;

[0060] Fig.21 It is the surface accumulation diagram under the indentation point 33 example in the third group of indentation experiments;

[0061] Fig. 22 It is a comparison diagram of load displacement curves under the example of indentation point 33;

[0062] Fig.23 It is a comparison diagram of the stacking height distance curve on the upper side of the indentation point in the example of indentation point 33;

[0063] Fig.24 It is a comparison diagram of the stacking height distance curve on the right side of the indentation point in the example of indentation point 33;

[0064] Fig.25 This is a structural block diagram of an electronic device provided by an embodiment of the present invention. DETAILED DESCRIPTION

[0065] In order to make the purpose, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are part of the embodiments of the present invention, not all of the embodiments. Generally, the components of the embodiments of the present invention described and shown in the drawings here can be arranged and designed in various different configurations.

[0066] Therefore, the following detailed description of the embodiments of the present invention provided in the accompanying drawings is not intended to limit the scope of the claimed invention, but merely represents selected embodiments of the present invention. All other embodiments obtained by a person of ordinary skill in the art based on the embodiments of the present invention without creative work are within the scope of protection of the present invention. It should be noted that similar numbers and letters represent similar items in the following drawings, so once an item is defined in one drawing, it does not need to be further defined and explained in subsequent drawings. In the description of the present invention, it should be noted that the features in the embodiments of the present invention can be combined with each other without conflict.

[0067] See also Figure 1, which is a flow chart of a TiAl alloy crystal plasticity finite element modeling method provided in an embodiment of the present invention. It should be understood that the operations of the flow chart may not be implemented in sequence, and steps without logical contextual relationships may be reversed in order or implemented simultaneously. In addition, under the guidance of the content of the present invention, those skilled in the art may add one or more other operations to the flow chart, or may remove one or more operations from the flow chart. The TiAl alloy crystal plasticity finite element modeling method may be executed by an electronic device, which may be a computer, server, or other device with data, image, and other processing capabilities. Figure 1 As shown, the method comprises the following steps:

[0068] S11, using electron backscatter diffraction technology to obtain grain data of a given material sample, wherein the given material sample is a TiAl alloy material sample.

[0069] S12, obtaining grain material properties based on electron backscatter diffraction data analysis software and the grain data.

[0070] S13, establishing a grain geometry model based on finite element analysis software and according to the grain data.

[0071] S14, assigning the grain material properties to the grain geometric model, and constructing an indentation finite element model.

[0072] S15, extracting crystal plasticity constitutive relationship information from a pre-written subroutine, and coupling the crystal plasticity constitutive relationship information to the indentation finite element model to obtain a crystal plasticity finite element model.

[0073] In this embodiment, a sample of the required size can be cut from a bulk material according to the simulation requirements. For example, the experimental material can be an extruded rod with a nominal chemical composition of Ti-43.5Al-4Nb-1Mo-0.1B (at%). In addition, an electrospark machining (EDM) method can be used to cut a large sample of 16 mm × 16 mm × 5 mm from the middle area of ​​the rod. The sample surface preparation steps include: the first step is grinding with a series of SiC sandpaper; then the next step is treated with porous chloroprene rubber with a particle size of 0.06 μm, and finally the titanium alloy electrolytic polishing solution with a composition of 5% perchloric acid, 35% n-butanol, and 60% methanol is electrolytically polished for 30 seconds at -15 degrees to zero degrees to facilitate EBSD observation.

[0074] On this basis, the electron backscatter diffraction EBSD technology is used to obtain the grain data of a given material sample. Among them, the grain data includes the phase information and grain information of the given material sample, and the grain information includes the surface Euler angle and grain morphology.

[0075] Specifically, the electron backscattered diffraction pattern on the surface of a given material sample can be detected based on the detector in the EBSD system, and the collected scattered diffraction pattern can be analyzed to obtain data such as phase information, grain morphology, surface Euler angles, etc.

[0076] The obtained grain data can be saved in a CTF format file, and the CTF file can be imported into the electron backscatter diffraction data analysis software OIM, and analyzed and processed in the OIM software to obtain the grain material properties including grain orientation information.

[0077] On the other hand, a grain geometry model can be established based on finite element analysis software, such as ABAQUS. Then, in the finite element analysis software, the grain geometry model is assigned with grain material properties, and then a TiAl alloy nanoindentation finite element model is constructed.

[0078] In addition, the crystal plasticity constitutive relationship information can be written and coupled to the indentation finite element model. After multiple iterative update processes, the final crystal plasticity finite element model can be obtained.

[0079] Specifically, the TiAl alloy includes a γ-TiAl phase and an α2-Ti3Al phase. The slip system in the γ-TiAl phase includes a normal slip system, a super slip system and a twin system. The slip system in the α2-Ti3Al phase includes a basal slip system, a cylindrical slip system and a conical slip system.

[0080] Since the <110] and <011] orientations of the γ phase of the L10 lattice structure in the γ-TiAl alloy lamellar structure are not crystallographically equivalent, this complex crystal orientation relationship has an important influence on the initiation and slip of the slip system during plastic deformation of the γ-TiAl alloy. The main slip systems in the γ-TiAl phase are: 4 ordinary slip systems <110]{111}, 8 super slip systems <011]{111} and 4 twin systems <112]{111}.

[0081] α2-Ti3Al is D0 19 Lattice structure, plastic deformation is mainly carried out by basal slip, cylindrical slip and cone slip. The main slip systems in α2-Ti3Al phase are: 3 basal slip systems {0001}< >, 3 cylindrical slip systems { }< >, 6 conical slip systems { }< >.

[0082] In this embodiment, the step of extracting the crystal plasticity constitutive relation information in the pre-written subroutine can be implemented in the following manner:

[0083] The initial orientation of the grains is selected in advance based on the dislocation slip deformation mechanism and the slip system in the γ-TiAl phase and the α2-Ti3Al phase, a finite element constitutive relationship model of the γ-TiAl crystal plasticity that comprehensively considers ordinary dislocations, super dislocations and twinning is established, and a finite element constitutive relationship model of the α2-Ti3Al crystal plasticity is established, the finite element constitutive relationship model of the γ-TiAl crystal plasticity and the finite element constitutive relationship model of the α2-Ti3Al crystal plasticity are written into a subroutine, and the crystal plasticity constitutive relationship information is obtained by extracting the subroutine.

[0084] In this embodiment, the subroutine has all the slip systems of the γ-TiAl phase and the α2-Ti3Al phase, and finally forms a for file. After extracting the crystal plasticity constitutive relationship information in the for file, a crystal plasticity finite element model suitable for TiAl alloy is finally formed.

[0085] The TiAl alloy crystal plasticity finite element modeling method provided in this embodiment realizes the process of crystal plasticity finite element modeling analysis, which greatly facilitates the simulation prediction of material mechanical properties. In addition, the modeling process is simple and convenient, and takes into account the real performance and constitutive relationship of the material, which helps to accurately predict the mechanical properties of the crystal and thus achieve microstructure optimization.

[0086] See also Figure 2 In this embodiment, the step of assigning the grain material properties to the grain geometric model and constructing the indentation finite element model may include the following sub-steps:

[0087] S141, assigning the grain material properties to the grain geometry model, and setting analysis steps and boundary conditions, wherein one analysis step includes a plurality of incremental steps.

[0088] S142, meshing the crystal grain geometry model to obtain a plurality of meshes.

[0089] S143, obtaining an indentation finite element model based on the meshed grain geometry model.

[0090] In this embodiment, the grain material properties can be assigned to the grain geometry model in the finite element analysis software, and the boundary conditions can be defined according to the actual experimental conditions. In addition, the analysis step can be set, and the analysis step can be understood as each stage in the modeling process, such as the indentation experiment includes two stages, loading and unloading, where the loading stage is one analysis step and the unloading stage is one analysis step. Each analysis step can include multiple incremental steps, which can be understood as dividing the time period corresponding to each stage into multiple small time segments, and each time segment is an incremental step.

[0091] When dividing the grid, a grid type suitable for the geometric shape of the grain can be selected, such as a hexahedron, a tetrahedron, etc. In this embodiment, specifically, an eight-node linear hexahedron grid can be used to divide the grain geometric model into multiple grids. In this process, the division can be performed based on a determined grid size.

[0092] In addition, in this embodiment, a local boundary region in the grain geometric model may be delineated, and the mesh in the local boundary region may be encrypted.

[0093] Specifically, the unit type can be assigned to the grain geometry model first, the area to be assigned the unit type can be selected, the area in the grain geometry model can be selected, and it can be assigned as an eight-node linear hexahedral unit. Seed points are placed on each edge of the grain geometry model, and the upper layer of the grain geometry model and the center area of ​​the indentation (i.e., the local area of ​​the boundary) are encrypted. Meshing is performed based on the laid seed points to obtain a model divided into multiple meshes.

[0094] The schematic diagram of the obtained grain geometry model is shown in Figure 3 , Figure 4 and Figure 5 As shown, Figure 3 and Figure 4 is a schematic diagram of a single crystal model. Figure 3 is a schematic diagram of the three-dimensional model of the grain geometry model. Figure 4 is a top view of the three-dimensional model. Figure 5 It is a top view of the twin crystal model (schematically showing a top view of grain 1 and grain 2, including the grain boundary line of grain 1 and grain 2).

[0095] In this embodiment, in the local area of ​​the boundary of the grain geometric model (such as Figure 3 The middle area of ​​the upper and middle surfaces of the model (the middle area of ​​the upper and middle surfaces) is encrypted relative to other areas. On the one hand, it can avoid the modeling efficiency being affected by too much processing workload due to too many meshes. On the other hand, the mesh in the local area of ​​the boundary based on the encryption processing can improve the modeling accuracy. In this way, the analysis accuracy can be improved, the calculation amount can be saved, and the convergence of the finite element analysis can be increased.

[0096] Based on the grain geometry model, the TiAl alloy nanoindentation finite element model of different single crystals, grain boundaries, and phase boundaries can be obtained. Pressure, i.e., load, can be applied to the grain surface to obtain the indentation finite element model. Figure 6Schematically shows four groups of indentation experiments performed on a series of treated material surfaces, wherein each group of indentation experiments has three indentation points. The first to fourth groups of indentation experiments are numbered 1-4, wherein the first group of indentation experiments has three indentation points, numbered 11, 12 and 13, respectively, the indentation points in the second group of indentation experiments are numbered 21, 22 and 23, respectively, the indentation points in the third group of indentation experiments are numbered 31, 32 and 33, respectively, and the indentation points in the fourth group of indentation experiments are numbered 41, 42 and 43, respectively. Figure 7 The third group of indentation experiments is shown in Figure 2. Figure 7 (a), and then electron backscatter diffraction was taken to obtain Figure 7 The other three pictures.

[0097] The three indentation points in the third group of indentation experiments were photographed using an atomic force microscope, and the Figure 8 The image shown in .

[0098] See also Fig. 9 In this embodiment, the step of coupling the crystal plasticity constitutive relationship information to the indentation finite element model to obtain the crystal plasticity finite element model may include the following sub-steps:

[0099] S151, based on the crystal plasticity constitutive relationship information, obtaining the Taylor cumulative shear strain on all slip and twin systems, and calculating the cumulative twin volume fraction based on the Taylor cumulative shear strain.

[0100] S152, taking each grid in the indentation finite element model as a unit integration point, and calculating the cumulative twin volume fraction of all twin variants in each unit integration point according to the number of twin systems turned on.

[0101] S153, after each incremental step, the accumulated twin volume fraction is compared with the dynamic threshold. If the accumulated twin volume fraction is greater than the dynamic threshold, the grain material information of the corresponding unit integration point is updated until the crystal plasticity finite element model is obtained after all incremental steps are completed.

[0102] In this embodiment, the For file obtained above is imported into the finite element analysis software for operation, the indentation finite element model is combined with the crystal plasticity theory represented by the crystal plasticity constitutive relationship information, and the final crystal plasticity finite element model is obtained through multiple iterative updates.

[0103] Specifically, crystal plasticity theory includes the following information:

[0104] Under load, the deformation of crystal materials includes elastic deformation and plastic deformation. Plastic deformation is mainly caused by the sliding of dislocations in the crystal along the activated slip system, while elastic deformation is mainly the distortion and rotation of the crystal lattice. When a load is applied to the crystal surface, the two deformation modes of elastic deformation and plastic deformation occur simultaneously, resulting in the crystal changing from the initial configuration to the current configuration.

[0105] Thus, the deformation gradient F Can be divided into elastic part and plastic part :

[0106] ;

[0107] in, represents the elastic part caused by elastic stretching and rigid body rotation, Represents the plastic part caused by dislocation slip.

[0108] Velocity gradient It can be expressed as the plastic shear strain rate component in the slip direction of the α slip system The sum of the normal vector of the sliding surface is represented as follows:

[0109] ;

[0110] in, represents the rate of change of plastic deformation gradient, It means taking the reciprocal of the parameter in brackets. represents the sliding direction vector, represents the normal vector of the slip surface, represents the tensor product, represents the shear strain rate of the αth slip system, α represents the slip system; the shear strain rate of the αth slip system is:

[0111] ;

[0112] in, , and are the reference values ​​of slip rate, decomposed shear stress and slip resistance, m is the reciprocal of the strain rate sensitive component, sgn represents the sign function, which returns an integer variable indicating the positive or negative sign of the subsequent parameter. is the sign of taking absolute value.

[0113] The evolution of anti-slip properties can be summarized as follows:

[0114] ;

[0115] in, represents the sliding resistance change rate, represents the shear strain rate of the β slip system, is the hardening modulus, which can be determined by the following formula:

[0116] ;

[0117] in, q is the hardening coefficient. When α = β, it indicates the self-hardening coefficient, that is, the hardening of the α slip system slip pair itself, and the value of q is 1. When α≠β, it indicates the latent hardening coefficient, that is, the hardening of the α slip system by other slip systems, and the value of q is 1.4. h (γ) is a function of γ and can be determined by the following formula:

[0118] ;

[0119] in, h 0 is the initial hardening modulus, is the initial critical decomposed shear stress, is the breakthrough stress when large plastic flow occurs, Sech represents a hyperbolic function, represents the Taylor cumulative shear strain on all slipping, twinning systems.

[0120] Based on the above theory, the Taylor cumulative shear strain on all slip and twin systems can be obtained by the following formula:

[0121] ;

[0122] t represents time.

[0123] The cumulative twin fraction is calculated based on the Taylor cumulative shear strain according to the following formula: :

[0124] ;

[0125] in, is the twin characteristic shear strain (obtained from Taylor cumulative shear strain), is the twin shear strain of the face-centered cubic crystal, and its fixed value is 0.707.

[0126] Each grid in the indentation finite element model is taken as a unit integration point. The cumulative twin volume fraction of the twin variants in each unit integration point is added together to calculate the cumulative twin volume fraction. The calculation formula is as follows:

[0127] ;

[0128] in, represents the cumulative twin volume fraction of the current increment, n twIndicates the number of twin systems turned on.

[0129] As can be seen from the above, the modeling process is divided into multiple incremental steps, and the grain orientation information can be updated after each incremental step. Specifically, the cumulative twin volume fraction obtained after each incremental step is compared with the dynamic threshold. If the cumulative twin volume fraction is greater than the dynamic threshold, the grain orientation information is updated. Otherwise, the grain orientation information is not updated after the current incremental step until the cumulative twin volume fraction is greater than the dynamic threshold.

[0130] The above dynamic threshold can be obtained in the following way:

[0131] The minimum twin volume fraction for orientation rotation and the evolution parameters of the twin volume fraction during plastic deformation are obtained; the dynamic threshold is obtained based on the minimum twin volume fraction, the evolution parameters and the cumulative twin volume fraction of the current incremental step.

[0132] In this embodiment, the dynamic threshold can be calculated based on the following formula: :

[0133]

[0134] in, represents the minimum twin volume fraction for orientation rotation to occur, is the evolution parameter, which determines the evolution of the twin volume fraction during plastic deformation. and Usually less than 1.

[0135] When the cumulative twin volume fraction is greater than the dynamic threshold after a certain incremental step, the grain material information of the corresponding unit integration point can be updated in the following ways:

[0136] The twin plane normal vector of the dominant twin system of the corresponding unit integration point is obtained; and updated grain orientation information is obtained based on the twin plane normal vector and the second-order unit vector.

[0137] In this embodiment, the updated grain orientation information can be obtained based on the following formula: :

[0138]

[0139] in, N tw represents the twin surface normal vector of the dominant twin system of the unit integration point, and I represents the second-order unit vector.

[0140] Based on the above method, the grain orientation information is updated after each incremental step until all the set incremental steps are completed, and the final crystal plasticity finite element model obtained by iteration is obtained based on the final grain orientation information.

[0141] Furthermore, the modeling method provided in this embodiment also includes the following steps:

[0142] The crystal plasticity finite element model is simulated to obtain simulation result data of nanoindentation points of a single grain and nanoindentation points at grain boundaries, and experimental result data of nanoindentation points of a single grain and nanoindentation points at grain boundaries are obtained; the simulation result data and the experimental result data are output in a graphical form based on visualization technology.

[0143] In this embodiment, material information such as physical phase and grain orientation obtained by real electron backscatter diffraction photography is input into a grain geometry model for simulation, and corresponding stress cloud maps and accumulation maps can be obtained.

[0144] in, Figures 10 to 14 is a schematic diagram of the indentation point 31 in the third group of indentation experiments, wherein: Fig.10 , Fig.11 The stress cloud map and surface accumulation map are respectively obtained by calculating the single grain nanoindentation example through modeling and simulation of this embodiment, wherein the stress cloud map and surface accumulation map are obtained after the simulation calculation of the nanoindentation crystal plasticity finite element model is completed, and are generated after the real material properties of the corresponding experiment are input and then simulated.

[0145] By extracting data from the plastic finite element model after the simulation run, the load-displacement curve can be obtained. Fig.12 This is a comparison diagram of the load-displacement curve obtained by simulating the crystal plasticity finite element model modeled in this embodiment and the load-displacement curve obtained by the actual indentation experiment.

[0146] The simulated stacking map and the surface stacking map taken by atomic force microscope are used for data extraction to obtain the stacking height distance curve. Fig.13 , Fig.14 This is a comparison diagram of the stacking height distance curve obtained by simulating the crystal plasticity finite element model modeled in this embodiment and the stacking height distance curve obtained by photographing the indentation point 31 with an atomic force microscope after the actual experiment.

[0147] Figures 15 to 19 is a schematic diagram of the indentation point 32 in the third group of indentation experiments, wherein: Fig.15 , Fig.16 The stress cloud map and surface accumulation map obtained by calculating the single grain nanoindentation example obtained by modeling and simulation in this embodiment are respectively. Fig.17This is a comparison diagram of the load-displacement curve obtained by simulating the crystal plasticity finite element model modeled in this embodiment and the load-displacement curve obtained by the actual experiment. Fig.18 , Fig.19 This is a comparison diagram of the stacking height distance curve obtained by simulating the crystal plasticity finite element model modeled in this embodiment and the stacking height distance curve obtained by photographing the indentation point 32 with an atomic force microscope after the actual experiment.

[0148] Figure 20 to Figure 24 is a schematic diagram of the indentation point 33 in the third group of indentation experiments, wherein: Fig. 20 , Fig.21 The stress cloud map and surface accumulation map are respectively calculated by the nanoindentation example at the grain boundary obtained by modeling and simulation of this embodiment. Fig. 22 This is a comparison diagram of the load-displacement curve simulated by the crystal plasticity finite element model modeled in this embodiment and the load-displacement curve obtained by the actual experiment. Fig.23 , Fig.24 This is a comparison diagram of the stacking height distance curve obtained by simulating the crystal plasticity finite element model modeled in this embodiment and the stacking height distance curve obtained by photographing the indentation point 33 with an atomic force microscope after the actual experiment.

[0149] From the comparison diagram of the above simulation results and the experimental results, it can be seen that the modeling simulation results in this embodiment are consistent with the experimental results, which further shows that the model constructed in this embodiment can help to accurately predict the mechanical properties of crystals and thus achieve microstructure optimization.

[0150] An embodiment of the present invention also provides an electronic device, such as Fig.25 As shown, the electronic device may be a computer device, and the electronic device may include a processor and a memory. In addition, the memory stores a computer program, and the processor implements the TiAl alloy crystal plasticity finite element modeling method provided in this embodiment by reading and executing the computer program corresponding to the above embodiment in the memory.

[0151] The memory, processor and other components are electrically connected to each other directly or indirectly through a system bus to achieve data transmission or interaction. The memory can be an information recording device based on any electronic, magnetic, optical or other physical principle, used to record execution instructions, data, etc. In some embodiments, the memory can be, but is not limited to, a volatile memory, a non-volatile memory, a storage drive, etc.

[0152] In some embodiments, the volatile memory may be a random access memory (RAM). In some embodiments, the non-volatile memory may be a read-only memory (ROM), a programmable read-only memory (PROM), an erasable programmable read-only memory (EPROM), an electric erasable programmable read-only memory (EEPROM), a flash memory, etc. In some embodiments, the storage drive may be a disk drive, a solid state drive, any type of storage disk (such as a CD, a DVD, etc.), or a similar storage medium, or a combination thereof, etc.

[0153] The communication unit is used to send and receive data through a network. In some embodiments, the network may include a wired network, a wireless network, a fiber optic network, a telecommunications network, an intranet, the Internet, a local area network (LAN), a wide area network (WAN), a wireless local area network (WLAN), a metropolitan area network (MAN), a wide area network (WAN), a public switched telephone network (PSTN), a Bluetooth network, a ZigBee network, or a near field communication (NFC) network, or any combination thereof. In some embodiments, the network may include one or more network access points. For example, the network may include a wired or wireless network access point, such as a base station and / or a network switching node, and one or more components of the service request processing system may be connected to the network through the access point to exchange data and / or information.

[0154] The processor may be an integrated circuit chip having a signal processing capability, and the processor may include one or more processing cores (e.g., a single-core processor or a multi-core processor). By way of example only, the processor may include a central processing unit (CPU), an application specific integrated circuit (ASIC), an application specific instruction set processor (ASIP), a graphics processing unit (GPU), a physical processing unit (PPU), a digital signal processor (DSP), a field programmable gate array (FPGA), a programmable logic device (PLD), a controller, a microcontroller unit, a reduced instruction set computer (RISC), or a microprocessor, or any combination thereof.

[0155] It should be understood that the apparatus and method disclosed in the above-mentioned embodiments can also be implemented in other ways. The apparatus embodiments described above are merely schematic. For example, the flowcharts and block diagrams in the accompanying drawings show the possible architecture, functions and operations of the apparatus, method and computer program product according to multiple embodiments of the present invention. In this regard, each box in the flowchart or block diagram can represent a module, a program segment or a part of a code, and a module, a program segment or a part of a code contains one or more executable instructions for implementing a specified logical function. It should also be noted that in some alternative implementations, the functions marked in the box can also occur in a different order from the order marked in the accompanying drawings. For example, two consecutive boxes can actually be executed substantially in parallel, and they can sometimes be executed in the opposite order, depending on the functions involved. It should also be noted that each box in the block diagram and / or the flowchart, and the combination of boxes in the block diagram and / or the flowchart, can be implemented with a dedicated hardware-based system that performs a specified function or action, or can be implemented with a combination of dedicated hardware and computer instructions.

[0156] The above are only various embodiments of the present invention, but the protection scope of the present invention is not limited thereto. Any person skilled in the art can easily think of changes or substitutions within the technical scope disclosed by the present invention, which should be included in the protection scope of the present invention. Therefore, the protection scope of the present invention should be based on the protection scope of the claims.

Claims

1. A TiAl alloy crystal plasticity finite element modeling method, characterized in that: The method comprises: Using electron backscatter diffraction technology to obtain grain data of a given material sample, wherein the given material sample is a TiAl alloy material sample; Obtaining grain material properties based on the electron backscatter diffraction data analysis software and the grain data; Establishing a grain geometry model based on finite element analysis software and according to the grain data; Assigning the grain material properties to the grain geometric model, and constructing an indentation finite element model, wherein the indentation finite element model includes TiAl alloy nanoindentation finite element models of different single crystals, grain boundaries, and phase boundaries; Extracting crystal plasticity constitutive relationship information from a pre-written subroutine, and coupling the crystal plasticity constitutive relationship information to the indentation finite element model to obtain a crystal plasticity finite element model; The TiAl alloy includes a γ-TiAl phase and an α2-Ti3Al phase, the slip system in the γ-TiAl phase includes a normal slip system, a super slip system and a twin system, the slip system in the α2-Ti3Al phase includes a basal slip system, a cylindrical slip system and a conical slip system, and the step of extracting the crystal plastic constitutive relationship information in the pre-written subroutine includes: Preliminarily selecting the initial orientation of grains based on the dislocation slip deformation mechanism, the slip system in the γ-TiAl phase and the α2-Ti3Al phase, establishing a γ-TiAl crystal plasticity finite element constitutive relationship model that comprehensively considers ordinary dislocations, super dislocations, and twinning, and establishing an α2-Ti3Al crystal plasticity finite element constitutive relationship model, writing the γ-TiAl crystal plasticity finite element constitutive relationship model and the α2-Ti3Al crystal plasticity finite element constitutive relationship model into a subroutine, and extracting the subroutine to obtain crystal plasticity constitutive relationship information; The step of assigning the grain material properties to the grain geometric model and constructing an indentation finite element model comprises: Assigning the grain material properties to the grain geometric model, and setting analysis steps and boundary conditions, wherein one analysis step includes a plurality of incremental steps, and the analysis steps are various stages in the modeling process, including a loading stage and an unloading stage in the indentation implementation; Meshing the grain geometric model to obtain a plurality of meshes; The indentation finite element model is obtained based on the meshed grain geometry model; The step of coupling the crystal plasticity constitutive relationship information to the indentation finite element model to obtain a crystal plasticity finite element model comprises: Based on the crystal plasticity constitutive relation information, Taylor cumulative shear strains on all slip and twin systems are obtained, and based on the Taylor cumulative shear strains, cumulative twin volume fractions are calculated; Taking each grid in the indentation finite element model as a unit integration point, and calculating the cumulative twin volume fraction of all twin variants in each unit integration point according to the number of twin systems turned on; After each incremental step, the accumulated twin volume fraction is compared with the dynamic threshold. If the accumulated twin volume fraction is greater than the dynamic threshold, the grain material information of the corresponding unit integration point is updated until a crystal plasticity finite element model is obtained after all incremental steps are completed. The method further comprises: Simulating the crystal plasticity finite element model to obtain simulation result data of nanoindentation points of a single grain and nanoindentation points at grain boundaries, and obtaining experimental result data of nanoindentation points of a single grain and nanoindentation points at grain boundaries; The simulation result data and the experimental result data are outputted in a graphical manner based on visualization technology.

2. The TiAl alloy crystal plasticity finite element modeling method according to claim 1, characterized in that: The step of meshing the grain geometric model to obtain a plurality of meshes comprises: Meshing the grain geometric model using an eight-node linear hexahedral mesh to obtain a plurality of meshes; A local boundary region in the grain geometric model is delineated, and meshes in the local boundary region are encrypted.

3. The TiAl alloy crystal plasticity finite element modeling method according to claim 1, characterized in that: The step of updating the grain material information of the corresponding unit integration point includes: Obtain the twin surface normal vector of the dominant twin system of the corresponding unit integration point; Updated grain orientation information is obtained based on the twin plane normal vector and the second-order unit vector.

4. The TiAl alloy crystal plasticity finite element modeling method according to claim 1, characterized in that: The dynamic threshold is obtained by: Obtain the minimum twin volume fraction for orientation rotation and the evolution parameters of the twin volume fraction during plastic deformation; A dynamic threshold is obtained based on the minimum twin volume fraction, the evolution parameter and the cumulative twin volume fraction of the current incremental step.

5. The TiAl alloy crystal plasticity finite element modeling method according to claim 1, characterized in that: The grain data includes phase information and grain information of the given material sample, and the grain information includes surface Euler angles and grain morphology.

6. An electronic device comprising a memory and a processor, wherein the memory stores a computer program that can be run on the processor, characterized in that: When the processor executes the computer program, the steps of the method according to any one of claims 1 to 5 are implemented.

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