CN-121999912-A - High-entropy alloy creep property prediction method based on microstructure dynamic evolution

CN121999912ACN 121999912 ACN121999912 ACN 121999912ACN-121999912-A

Abstract

The invention provides a high-entropy alloy creep property prediction method based on microstructure dynamic evolution, and belongs to the technical field of alloy material property prediction. Aiming at the problems that the existing method excessively depends on an empirical formula, macroscopic performance and microscopic mechanism to fracture, the invention constructs a multi-physical field coupling dynamics calculation frame. The framework integrates dislocation dynamics, vacancy diffusion and non-uniform lattice strain theory, and describes the dynamic interaction and co-evolution of dislocation, vacancy and lattice strain. And synchronously solving dislocation evolution, vacancy diffusion and interaction between the dislocation evolution and the vacancy diffusion and lattice strain in each time step, so as to realize real-time bidirectional coupling of the dislocation evolution, the vacancy diffusion and the lattice strain. Experiments prove that the method can accurately predict the creep performance of the entropy alloy and directly generate a creep strain-time curve. The method can quantitatively evolve microstructure in the creep process based on intrinsic parameters and service conditions of materials, and provides efficient theoretical tools and calculation platforms for creep-resistant design of high-entropy alloy.

Inventors

LI JIA
FANG QIHONG
WANG SHUO
CHEN YANG
FENG HUI

Assignees

湖南大学

Dates

Publication Date: 20260508
Application Date: 20260316

Claims (7)

1. The method for predicting the creep performance of the high-entropy alloy based on the dynamic evolution of the microstructure is characterized in that a dynamic frame for coupling the evolution of the multiple physical fields is constructed by comprehensively considering crystallographic theory, thermodynamic theory, integrated dislocation movement and proliferation evolution and vacancy generation/annihilation and diffusion driven by thermodynamic mechanics and combining the special lattice distortion effect of the high-entropy alloy, and is used for predicting the creep performance of the high-entropy alloy, and the method is characterized in that: The interaction mechanism of the high-entropy alloy is quantitatively revealed through the collaborative dynamic evolution process of microstructures such as dislocation, vacancy concentration and lattice strain field under the numerical simulation loading condition, and the high-entropy alloy creep curve with a macroscopic scale is directly related and derived, so that creep load, environmental factors and material parameters can be regulated and controlled, microstructure evolution and creep curves of different high-entropy alloy materials under different conditions are obtained, and theoretical guidance is provided for designing high-entropy alloy with excellent creep resistance.
2. The method for predicting the creep performance of the high-entropy alloy based on the dynamic evolution of the microstructure according to claim 1, wherein the method is characterized in that the evolution and interaction of various microstructures are accurately simulated and calculated by utilizing the inherent parameters of materials, creep load, temperature and other conditions, and the creep deformation is further derived according to the evolution of the microstructures.
3. The method of use according to any one of claims 1-2, said treatment comprising the specific steps of: Determining basic material parameters required in a dynamic frame, external environment conditions and load related physical parameters, determining initial conditions of model evolution, calculating dislocation motion through dislocation theory, dislocation reaction and plastic deformation under the open-source discrete dislocation dynamic frame, fitting a fractal function to a lattice strain field of the high-entropy alloy, calculating a vacancy concentration field after diffusion through three-dimensional discrete Fourier transformation, coupling the dynamic processes together, and jointly evolving, wherein creep time is a time step of dynamic simulation, and creep deformation can be calculated through the dislocation theory: (1) Wherein the method comprises the steps of In order to achieve a plastic strain rate, As the slip plane direction vector, As the bergs vector of the dislocation segment, For the size of the kinetic model, For the area swept by the dislocation segment during this time, For time, according to this method, the time step of each time step and the corresponding plastic deformation are superimposed, and a creep plastic deformation-time curve is obtained.
4. According to claim 3, the motion of dislocation is calculated by dislocation theory, wherein the motion speed of dislocation nodes can be expressed as (2) Wherein, the In order for the shear stress to be a shear stress, For the magnitude of the bergs vector, Mobility of dislocation movement, mobility of dislocation slip Can be obtained by consulting parameters or molecular dynamics simulation, and for the Cantor alloy adopted in the study, The rate of dislocation slip is, in addition, related to the vacancy diffusion, the relative mobility is described by (3) Wherein, the For the large mobility of the climb of dislocations, In order for the diffusion coefficient to be the same, In order to achieve a concentration of vacancies, In the form of an atomic volume, Is a boltzmann constant value, In order to be able to determine the temperature, Indicating a distance from the dislocation which is far away, Is the dislocation core radius.
5. A lattice strain field of a high entropy alloy as claimed in claim 3, obtained by a three-dimensional fractal function in combination with a high resolution electron transmission microscope and geometric phase analysis method, wherein the fractal strain field is expressed as (4) Wherein, the The magnitude of the strain is at random locations, In order to be able to achieve a strain amplitude, For the dimension of the fractal, As a fractal plane flatness parameter, To construct the number of superimposed ridges of the strain field profile, For the number of iterations, In order to be a random phase of the light, For the length of the sample, The lattice strain field is introduced into an established dynamic frame through the above formula, and the strain amplitude and fractal dimension are obtained by fitting a lattice distortion field obtained through high-resolution electron transmission microscopy and geometric phase analysis for unit vectors uniformly distributed on the hypersphere.
6. A diffusion process of the vacancy concentration field according to claim 3 is obtained by a three-dimensional discrete fourier transform, and in order to facilitate calculation of the diffusion of the vacancy concentration field, the entire simulation area is discretized into N areas in each direction, and the Fick second law of diffusion can be expressed as: (5) wherein l, m, n each represent an index at a different location in the discrete analog region, Represents the vacancy concentration of the discrete regions corresponding to l, m, n, By solving the above diffusion equation for the distance between two adjacent discrete regions, the concentration profile in fourier space after vacancy diffusion can be expressed as: (6) wherein t represents the diffusion time, and finally obtaining the concentration distribution of the vacancies after diffusion through inverse Fourier transform: (7) where i is an imaginary unit.
7. According to claim 3, in the present kinetic framework, the microstructures of dislocations, vacancy concentration fields and lattice distortion fields are not merely independent evolutions, but rather interact with each other, taking into account the combined effects of dislocation absorption and emission of vacancies, and plastic deformation to create new vacancies, and within each discrete region, the change in vacancy concentration can be expressed as: (8) Wherein the method comprises the steps of The concentration of the bit vacancies, Is a constant, describing the concentration of vacancies created by the deformation work, In order to be able to measure the stress, In order for the energy of formation of the vacancies, In order for the dislocation density to be the same, For dislocation alignment coefficients, the lattice strain field affects the motion of dislocations by changing the local reach-Koehler forces: (9) (10) Wherein, the Forces to align the misalignment nodes for externally applied creep loads, Forces on this dislocation node for other dislocation segments, The effect on the node of locally generated stress for the lattice strain field, As the berges vector of the dislocation segment ij, As a direction vector of the dislocation segment ij, Representing the dislocation segment ij, The contribution of the Peach-Koehler force to the motion of the misplacement node is between 0 and 1, For the Peach-Koehler force, Contributing to the length of the dislocation segment, Indicating the total force experienced by the dislocation node.

Description

High-entropy alloy creep property prediction method based on microstructure dynamic evolution Technical Field The invention belongs to the technical field of advanced alloy material calculation and performance prediction, and particularly relates to a high-entropy alloy creep performance prediction method based on microstructure dynamic evolution. The invention aims to construct a multi-physical field dynamic framework for coupling dislocation movement and proliferation, vacancy generation/annihilation and diffusion and multi-component lattice distortion field evolution through integrating material crystallography, point defect thermodynamics and dynamics theory. The method is characterized in that quantitative prediction of macroscopic creep behavior of the high-entropy alloy is realized through numerical simulation under the action of creep load by the cooperative dynamic evolution of the various microstructures and the complex interaction process of the cooperative dynamic evolution. The invention can systematically regulate and control parameters such as load, temperature, material composition and the like, simulate the evolution of microstructures under different conditions and derive corresponding creep curves, and provides key theoretical basis and calculation tools for designing and optimizing high-entropy alloy materials with excellent creep resistance. Background The high-entropy alloy shows excellent performances superior to the traditional alloy by virtue of core effects brought by the unique multi-principal element characteristics, namely, the high-entropy effect, the lattice distortion effect, the delayed diffusion effect and the cocktail effect, and is particularly expected to be suitable for extreme service environments such as hot-end components of aeroengines, advanced nuclear reactor materials and the like. However, its deformation and failure mechanisms become extremely complex and elusive, due to its very complex intrinsic properties. In the research and application process of the high-entropy alloy, the accurate prediction and efficient design of the creep property of the high-entropy alloy become important bottlenecks for restricting the creep property of the high-entropy alloy to be the next-generation key structural material. For high-entropy alloys, understanding and predicting this process has heretofore lacked a complete theoretical framework and computational tools that can penetrate the microscopic mechanisms and macroscopic behavior. Traditional methods of evaluating and predicting creep properties of alloys present significant limitations in the face of the complex microstructures typical of high-entropy alloys. The experimental driven empirical methods that are widely used today are very dependent on long-term and expensive creep experiments performed under specific composition and process conditions. While they can obtain the first hand data, the huge composition design space of high entropy alloys makes this approach similar to sea fishing needles. The time and economic costs required for trial-and-error are extremely high, and the empirical formulas or parameters obtained are often limited to narrow test conditions and are difficult to extrapolate to other components and conditions of use. Basically, the method only establishes a black box type association between external conditions and macroscopic response, and cannot reveal the inherent physical rule of how the microstructure in the material responds and evolves. Therefore, the theoretical guiding ability to optimize performance through the active design of the microstructure is lost. In an effort to seek an explanation based on physical mechanisms, researchers have attempted to migrate classical creep theory into high entropy alloy systems. In macroscopic-unique high-entropy alloy creep constitutive models, the behavior of high-entropy alloy creep is described by introducing some apparent material parameters, such as activation energy, stress index. However, these models are in essence an extremely simplified and averaged over complex microscopic processes. They have difficulty accurately reflecting the unique physical characteristics in high entropy alloys. Such as non-uniform lattice distortion fields in high entropy alloys. Its presence not only significantly increases the frictional resistance to dislocation slip, but more importantly, it creates a highly non-uniform local stress/strain environment that severely affects the overall process of dislocation motion, diffusion and annihilation. In this case, the concept of "average stress" in the conventional model is difficult to be equivalent. In addition, the diverse composition of high entropy alloys causes complex diffusion behavior. The large difference in diffusion rates of the components and their coupling to point defects such as vacancies makes dislocation movement to control creep deformation extremely complex. The mere introduction of an apparent diffusion