A Lattice Strain-Based Phase-Field Method for Controlling Creep Structures Based on Interface Input / Output

Abstract

This invention discloses a phase-field method for controlling creep microstructure through lattice strain using an interface-based input / output system. This method provides a visual input / output interface, enabling direct input / output of parameters and computational data. By establishing a dual-sublattice thermodynamic model coupled with a crystal phase-field kinetic model, and setting initial kinetic and thermodynamic parameters, the creep microstructure morphology is controlled by altering the coherent mismatch degree between the precipitated phase and the matrix phase, as well as the magnitude of external stress and strain. This invention, while enabling control of creep microstructure morphology, also includes a visual operating interface, making the computer simulation process more convenient and efficient. The combination of the crystal plastic phase-field method and the operating interface module yields rich simulation results, providing theory and methods for establishing the relationship between creep microstructure and strain in high-temperature alloys, as well as for the optimization design of microstructure control.

Description

Technical Field

[0001] This invention relates to the field of phase field simulation of high-temperature alloys, and specifically to a phase field method for controlling creep structure based on interface input / output using lattice strain. Background Technology

[0002] High-temperature alloys possess good high-temperature strength, excellent resistance to oxidation, hot corrosion, and fatigue, and are mainly used in modern aero-engines, rocket engines, and industrial gas turbine engines. Their primary failure mode is creep failure at high temperatures, making the study of the microscopic mechanism of creep crucial. Phase-field methods, aided by computer simulations, can investigate the influence of various variables on the evolution of alloy microstructure, saving time and material costs. Currently, the most commonly used phase-field model is the elastic phase-field model. However, experiments have shown that rafting is accompanied by a large number of dislocation movements, indicating that the rafting process of high-temperature alloys is a plastic process. Furthermore, the introduction of plastic strain accelerates the rafting process during creep rafting. Therefore, a crystal plasticity model is introduced to establish an elasto-plastic phase-field model.

[0003] This study found that lattice strain has a certain influence on the creep properties of high-temperature alloys. Therefore, a method for controlling the creep microstructure through lattice strain needs to be designed to simulate the microstructure under different lattice strains, thus providing a reference for the research and design of high-temperature alloys. A visual interface for controlling the creep microstructure through lattice strain is developed. The interface is designed using a programming language, enabling convenient input and output based on the retrieved research parameters, including the influence of lattice mismatch. Simulated microstructure diagrams can be obtained quickly and easily. By studying the simulation diagrams under different strain conditions, the characteristics of each creep process and stage can be analyzed, allowing for the measurement of creep performance. Introducing creep damage variables further improves the accuracy of the simulated creep process. Summary of the Invention

[0004] The purpose of this invention is to provide a method for controlling creep microstructure through a visual interface. By changing relevant parameters through a visual interface, a creep microstructure simulation diagram corresponding to the parameter is obtained, revealing the influence mechanism of lattice strain on the creep process of the alloy, and realizing the control of creep microstructure through lattice strain.

[0005] The technical solution of this invention is:

[0006] A method for controlling creep microstructure by lattice strain through a visual interface includes the following steps:

[0007] A method for controlling the phase field of creep structure by lattice strain through interface input and output, characterized in that it includes:

[0008] (1) Compile the input / output operation interface program module to establish the interface and visualization interface for phase field parameters and calculation data;

[0009] (2) Establish a double sublattice thermodynamic model and a crystal plastic phase field model based on the alloy composition;

[0010] (3) Write a program based on the model described in step (2) to determine the dynamic and thermodynamic parameters, and set the initial values ​​of variables such as temperature, stress, composition, lattice strain, and calculation parameters such as iteration steps and iteration step size;

[0011] (4) Based on the phase field equation, the micromorphological evolution diagram under continuous lattice strain is calculated and drawn using the kinetic and thermodynamic parameters of step (3), and the data on the evolution of precipitated phase creep structure affected by lattice strain are obtained.

[0012] (5) According to the interface program module, the calculation output result is the microstructure image corresponding to the input parameters. Through the microstructure image and the evolution data of step (4), a method for lattice strain-controlled creep microstructure is established.

[0013] Compared with existing technologies, the beneficial effects of this invention are as follows:

[0014] This method studies the evolution of microstructure under different lattice mismatches and strain directions by simulating changes in the magnitude of applied strain. Creep damage variables are introduced in the third stage of creep to improve the accuracy of the creep simulation process and to measure creep performance. The outstanding feature of the visualization interface is the data input and output interface, which facilitates and quickly expands the data input and output. The creep process law is obtained through simulation diagrams, realizing the method of lattice strain controlling creep microstructure. Attached Figure Description

[0015] Figure 1 This is the visual interface created in step 3 of the method described in this invention.

[0016] Figure 2 This is a diagram showing the evolution of microstructure under continuous lattice strain in step 4 of the method described in this invention.

[0017] Figure 3 This is a simulation diagram of creep structure obtained by lattice strain control in step 5 of the method described in this invention. The lattice mismatch degree of (a) is... (b) has a lattice mismatch degree of (c) has a lattice mismatch degree of Detailed Implementation

[0018] To better understand the technical content of the present invention, specific embodiments are described below in conjunction with the accompanying drawings.

[0019] The embodiments of the present invention are not necessarily intended to include all aspects of the invention. It should be understood that the various concepts and embodiments described above, as well as those described in more detail below, can be implemented in any of many ways, because the concepts and embodiments disclosed herein are not limited to any particular implementation. Furthermore, some aspects of the present invention can be used alone or in any suitable combination with other aspects disclosed herein.

[0020] This invention establishes a crystal plastic phase-field model based on the Ginzburg-Landau theory to realize the microscopic evolution process of alloy microstructure under continuous lattice strain. By using microstructure simulation diagrams, it predicts the evolution of creep microstructure under different lattice strains, enabling microscopic to macroscopic level study of creep process microstructure. Coupled with crystal plasticity theory, an elastoplastic phase-field model is established. The introduction of plastic strain more accurately describes the rafting mechanism and can convert microscopic plastic deformation into creep strain, thus enabling the measurement of alloy creep performance. The introduction of creep damage variables, taking into account the damage variables of the third stage of creep, can more accurately simulate the creep process.

[0021] This invention discloses a lattice strain-controlled creep microstructure phase field method with an interface input / output. This method establishes a visual input / output interface, enabling direct input / output of parameters and computational data. By establishing a dual sublattice thermodynamic model coupled with a crystal phase field dynamic model, initial dynamic and thermodynamic parameters are set. By changing the coherence mismatch degree between the precipitated phase and the matrix phase, as well as the magnitude of external stress and strain, the creep microstructure morphology is controlled. The method includes the following specific steps:

[0022] (1) Compile the input / output operation interface program module to establish the interface and visualization interface for phase field parameters and calculation data;

[0023] The visualization interface is based on the MatlabGUI programming language, with callback functions as the core of the programming language. Through further code compilation, a series of interfaces are designed and called, including: a startup waiting interface, a welcome interface for the program, a parameter input main interface, a running prompt box interface, and an output simulation graph interface.

[0024] The deploytool language is used to package and process multiple interfaces of a program, enabling quick access to the computer desktop;

[0025] The callback function, which inputs parameters into the main interface, is characterized by human-computer interaction and serves as the core of the program's execution. Its core code is as follows:

[0026] a=get(handles.kj1,'String');

[0027] time = str2num(a);

[0028] b=get(handles.kj2,'String');

[0029] Variable1 = str2num(b);

[0030] c=get(handles.kj3,'String');

[0031] Variable2 = str2num(c);

[0032] d=get(handles.kj4,'String');

[0033] Variable3 = str2num(d);

[0034] e=get(handles.kj5,'String');

[0035] Variable4 = str2num(e);

[0036] f=get(handles.kj6,'String');

[0037] Variable5 = str2num(f);

[0038] msgbox('Running...','warn','non-modal');

[0039] figure;

[0040] Co10Al9W_damage1(0.1,0.09,0.1,0.1,256,time,1173,Variable1,Variable2,Variable3,

[0041] Variable4, Variable5);

[0042] The above code is used to implement the input of parameters on the main interface, including time, Variable1, Variable2, Variable3, Variable4, and Variable5, which correspond to: the number of running steps, the lattice mismatch degree of Al, the lattice mismatch degree of W, ε22, ε23, and ε33, respectively. The number of parameters can be set and expanded as needed.

[0043] (2) Establish a dual sublattice thermodynamic model and a crystal plastic phase field model based on single-crystal high-temperature alloys;

[0044] The process of establishing the two sublattice thermodynamic model is as follows:

[0045] The free energy F of a single-crystal superalloy is given by the following formula:

[0046]

[0047] In the formula f ch For chemical energy, f el For elastic strain energy, f int For interface energy;

[0048] In the formula, the elastic strain energy f el The expression is:

[0049]

[0050] In the formula C ijkl For the elastic modulus tensor, and For elastic strain tensors in different dimensions;

[0051] elastic strain It can be written as:

[0052]

[0053] In the formula For uniform strain, δε ij For non-uniform strain, This is intrinsic strain, i.e., lattice mismatch. It is a microelastic strain;

[0054] The process of establishing a crystal plastic phase-field model is as follows:

[0055] Microplastic strain Its characteristic is that it is achieved through dislocation slip, and its expression is:

[0056]

[0057] In the formula m α For orientation tensor, The shear strain of each slip system can be written as:

[0058]

[0059] In the formula The initial shear rate is given, m = 4.5 represents the strain rate sensitivity, and τ... α and These are the shear stress and the critical shear stress, respectively.

[0060] By coupling Kachanov's creep damage theory, creep damage was considered, and the shear stress τα This can be expressed as:

[0061]

[0062] In the formula ω α σ is the damage variable that plays a role in the third stage of creep; σ is the stress, and ":" is the tensor double dot product symbol.

[0063] (3) Write a program based on the model described in step (2) to determine the dynamic and thermodynamic parameters, and set the initial values ​​of variables such as temperature, stress, composition, lattice strain, and calculation parameters such as iteration steps and iteration step size;

[0064] (4) Based on the phase field equation, the micromorphological evolution diagram under continuous lattice strain is calculated and drawn using the kinetic and thermodynamic parameters of step (3), and the data on the evolution of precipitated phase creep structure affected by lattice strain are obtained.

[0065] (5) According to the interface program module, the calculation output result is the microstructure image corresponding to the input parameters. Through the microstructure image and the evolution data of step (4), a method for lattice strain-controlled creep microstructure is established.

[0066] Example

[0067] Step 1: Compile the input / output operation interface program module to establish the interface and visualization interface for phase field parameters and calculation data, including input parameters: number of running steps, Al lattice mismatch degree, W lattice mismatch degree, ε22, ε23, ε33 and output results. Figure 1 The visualization interface shown is used to implement human-computer interaction. Users can input the number of running steps, Al lattice mismatch degree, W lattice mismatch degree, ε22, ε23, and ε33, and click "Run" to obtain the simulation diagram.

[0068] Step 2: Establish a dual sublattice thermodynamic model and a crystal plastic phase field model for the Co-10at.%Al-8at.%W alloy;

[0069] Step 3: Write a program to simulate the creep process of Co-10at.%Al-8at.%W alloy through phase field simulation. The grid size is 1024nm×1024nm, the temperature is set to 1173K, the applied stress is 316MPa, and the applied direction is the y* axis.

[0070] Step 4: Calculate and plot the microstructure evolution diagram under continuous lattice strain. Figure 2 The microstructure diagram is shown, with lattice strain extending along the x-axis from... Increase to The law governing the evolution of precipitated phase creep structure accelerated by lattice strain was obtained.

[0071] Step 5, input parameters: (1) Run step number is 555000, Al lattice mismatch is 0.1473, W lattice mismatch is 0.1693, ε22 is 0, ε23 is 0.16, ε33 is 0; (2) Run step number is 555000, Al lattice mismatch is 0.1673, W lattice mismatch is 0.1893, ε22 is 0, ε23 is 0.16, ε33 is 0; (3) Run step number is 555000, Al lattice mismatch is 0.1873, W lattice mismatch is 0.2093, ε22 is 0, ε23 is 0.16, ε33 is 0, obtain the microstructure simulation diagram under the corresponding parameters, and analyze the creep process law under different lattice strains through the simulation diagram.

[0072] Figure 3 The figures show simulated creep microstructures of alloy precipitates under different lattice strains. (a) shows the evolution of Al with a lattice mismatch of 0.1473 and W with a lattice mismatch of 0.1693; (b) shows the evolution of Al with a lattice mismatch of 0.1673 and W with a lattice mismatch of 0.1893; and (c) shows the evolution of Al with a lattice mismatch of 0.1873 and W with a lattice mismatch of 0.2093. Under different lattice mismatches, the larger the lattice mismatch, the greater the creep rate and the more pronounced the creep effect.

Claims

1. A method for controlling the phase field of creep structure through lattice strain via interface input and output, characterized in that: include: (1) Compile the input / output operation interface program module to establish the interface and visualization interface for phase field parameters and calculation data; (2) Establish a double sublattice thermodynamic model and a crystal plastic phase field model based on the alloy composition; (3) Write a program based on the model described in step (2) to determine the dynamic and thermodynamic parameters, and set the initial values ​​of the parameters for calculating temperature, stress, composition, lattice strain variables, iteration steps, and iteration step size; (4) Based on the phase field equation, the micromorphological evolution diagram under continuous lattice strain is calculated and drawn using the kinetic and thermodynamic parameters of step (3), and the data on the evolution of precipitated phase creep structure affected by lattice strain are obtained. (5) According to the interface program module, the calculation output result is the microstructure image corresponding to the input parameters. Through the microstructure image and the evolution data of step (4), a method for lattice strain-controlled creep microstructure is established. In step (2), a crystal plastic phase field model is established based on the single-crystal high-temperature alloy. The process is as follows: Microplastic strain Its characteristic is that it is achieved through dislocation slip, and its expression is: In the formula m α For orientation tensor, The shear strain of each slip system can be written as: In the formula The initial shear rate is given, m = 4.5 represents the strain rate sensitivity, and τ... α and These are the shear stress and the critical shear stress, respectively. By coupling Kachanov's creep damage theory, creep damage was considered, and the shear stress τ α This can be expressed as: In the formula ω α The damage variable plays a role in the third stage of creep, where σ is the stress and ":" is the tensor double dot product symbol.

2. The method according to claim 1, characterized in that: In step (1), The visualization interface is based on the MatlabGUI programming language, with callback functions as the core of the programming language. Through further code compilation, a series of interfaces are designed and called, including: a startup waiting interface, a welcome interface for the program, a parameter input main interface, a running prompt box interface, and an output simulation graph interface. The deploytool language is used to package and process multiple interfaces of a program, enabling quick access to the computer desktop.

3. The method according to claim 1, characterized in that: In step (2), a dual sublattice thermodynamic model is established based on the single-crystal high-temperature alloy. The process is as follows: The free energy of a single-crystal superalloy is given by the following formula: In the formula, the elastic strain energy f el The expression is: elastic strain It can be written as: In the formula For uniform strain, δε ij For non-uniform strain, This is intrinsic strain, i.e., lattice mismatch. For microelastic strain, f ch For chemical energy, f el For elastic strain energy, f int For interface energy, C ijkl For the elastic modulus tensor, and For elastic strain tensors in different dimensions.

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