Atomic mechanism analysis method for stress cycle and fatigue behavior of amorphous alloy
The amorphous alloy samples were prepared and loaded through molecular dynamics to achieve the acquisition of stress cyclic loading smooth curves, which solved the problem that it was difficult to explore the stress cyclic loading mechanism of amorphous alloys in the prior art, and effectively regulated the structure and mechanical properties of amorphous alloys.
Patent Information
- Application Number
- CN202510142412.7
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-02-08
- Publication Date
- 2025-05-23
AI Technical Summary
The prior art is difficult to effectively explore the mechanism of stress cyclic loading in amorphous alloys, resulting in the inability to obtain a stress cyclic loading smooth curve consistent with the experiment, and the structural and mechanical properties of the amorphous alloys cannot be accurately regulated.
Amorphous alloy samples were prepared by step cooling by molecular dynamics. Through multiple tensile loading and stress cycle loading, a smooth stress strain curve was achieved. The structure was characterized by the Voronoi polyhedral method, and the atomic mechanism of stress cycle loading and fatigue behavior was explored.
The obtained stress cycle loading smooth curve consistent with the experiment was achieved, the internal mechanism of stress cycle loading was explored, and a way to regulate the viscoelasticity and structural state of amorphous alloys was provided.
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Figure CN120028166A_ABST
Abstract
Description
Technical Field
[0001] The invention belongs to the technical field of molecular dynamics simulation of amorphous alloys, and in particular relates to a method for obtaining a stress-strain curve by molecular dynamics of stress cycle loading of amorphous alloys to analyze the atomic mechanism of stress cycle and fatigue behavior. Background Art
[0002] Amorphous alloys can be prepared by rapid cooling of high-temperature melts, and have structural characteristics of short-range order and long-range disorder. As an amorphous metal material with a special atomic structure, it has unique physical and mechanical properties, and can exhibit high hardness, high strength, good soft magnetic properties, corrosion resistance and other characteristics, making amorphous alloys have broad application prospects in many fields, including aerospace, electronic information, biomedicine, precision machinery and other fields. With the increasing demand for high-performance materials in modern industry, a new, reliable and efficient method for regulating the structural state of amorphous alloys is urgently needed to meet the increasingly diversified and refined application needs. Cyclic loading is an effective way to regulate the structure and properties of amorphous alloys.
[0003] However, the structure of amorphous alloys is complex, and its cyclic loading mechanism is still unclear. In terms of experiments, we can only explore the stress cyclic loading parameters. Therefore, it is extremely urgent to explore the stress cyclic loading mechanism in amorphous alloys, which can provide theoretical guidance for experiments and provide a quantitative range of stress cyclic loading parameters for experiments.
[0004] Most of the existing stress cyclic loading are based on laboratory measurements, and the microevolution during the cyclic loading process cannot be obtained. However, the stress cyclic loading calculated by the molecular dynamics method does not solve the problem of experimental and simulated spatial differences, and the calculation results are significantly different from the experimental measurement results. The purpose of the present invention is to provide a stress cyclic loading method that can achieve a smooth stress-strain curve in molecular dynamics, and to achieve a stress cyclic loading smooth curve consistent with the experiment, so as to explore the way to regulate the viscoelasticity and structural state of amorphous alloys by stress cyclic loading. Summary of the invention
[0005] The purpose of the present invention is to avoid the shortcomings of the prior art and provide an atomic mechanism analysis method for stress cycling and fatigue behavior of amorphous alloys, so as to achieve a smooth stress cycling loading curve consistent with the experiment, which can not only study the viscoelastic change mechanism of stress cycling loading, but also regulate the structure and mechanical properties of amorphous alloys; and provide a controllable regulation method for stress cycling loading or fatigue behavior of different materials, thereby solving the problems in the prior art.
[0006] To achieve the above object, the technical solution adopted by the present invention is an atomic mechanism analysis method for stress cycling and fatigue behavior of amorphous alloys, comprising the following steps:
[0007] Step 1: Generate amorphous alloy configuration:
[0008] The amorphous alloy samples were prepared by a molecular dynamics method in a step-by-step cooling method. Specifically, a crystalline sample was first prepared, the temperature was raised to above the melting temperature T, and a high-temperature equilibrium state was obtained by relaxing for 2ns at the temperature T. Then, the amorphous alloy configurations at different temperatures were obtained by a step-by-step cooling method with a temperature reduction of 50K per step.
[0009] Step 2: Use molecular dynamics method to perform multiple tensile loading on the amorphous alloy to achieve a smooth stress-strain curve:
[0010] Based on the amorphous alloy configurations at different temperatures obtained in step 1, the amorphous alloy is subjected to tensile loading using a molecular dynamics method; different velocity distributions are used for the same amorphous alloy configuration to achieve 50-100 times of stress-strain measurement to obtain a smooth stress-strain curve; based on the smooth tensile loading stress-strain curve, the elastic stage, yield stage and yield stress value of the amorphous alloy sample during tensile loading are determined;
[0011] Step 3: Apply stress cyclic loading to the amorphous alloy:
[0012] Based on the amorphous alloy configurations at different temperatures obtained in step 1, stress cyclic loading is performed by applying different stress amplitudes; to ensure the smoothness of the curve, stress cyclic loading is applied multiple times with different velocity distributions constructed for the same configuration, and finally the results are averaged;
[0013] Step 4: Use the smooth stress cycle loading curve obtained in step 3 to analyze the atomic mechanism of stress cycle and fatigue behavior:
[0014] Quantify the stress cyclic loading curve of amorphous alloys, make qualitative comparison with the stress cyclic loading curve obtained experimentally, and then explore the atomic mechanism of stress cyclic loading and fatigue behavior; observe the atomic response during the loading process, calculate the local structural characteristics during the loading process, and explore the structural evolution and dynamic evolution during stress cyclic loading.
[0015] Furthermore, in step 1, the melting temperature T of the amorphous alloy sample is 2000-3000K.
[0016] Furthermore, in the step 2, the amorphous alloy structure is characterized by a Voronoi polyhedron method, wherein the Voronoi polyhedron is a polyhedron formed by connecting the connecting lines of the central atom and all its nearest neighbor atoms with perpendicular bisectors and all the perpendicular bisectors.
[0017] Furthermore, in step three, the stress amplitude of the stress cycle loading is determined by the yield stress value obtained in step two, and stress amplitudes of different sizes lower than the yield stress are selected.
[0018] Furthermore, in the step 4, the activation of clusters at different cycle times is statistically analyzed to observe the regular changes in the structure and kinetic activation of the amorphous alloy.
[0019] The beneficial effects of the present invention are as follows: the present invention provides an atomic mechanism analysis method for stress cycling and fatigue behavior of amorphous alloys, which achieves the acquisition of a smooth stress cycling loading curve consistent with the experiment, thereby exploring the intrinsic mechanism of stress cycling loading and the way to regulate the viscoelasticity and structural state of amorphous alloys; the method realizes the change of atomic structure at different numbers of cycles during stress cycling loading at different temperatures in different systems, and can realize the dynamic evolution and structural evolution of different systems at different temperatures and different numbers of cycles. BRIEF DESCRIPTION OF THE DRAWINGS
[0020] Figure 1 It is an implementation flow chart of the present invention;
[0021] Figure 2 The embodiments of the present invention use molecular dynamics simulation to achieve the unsmooth and smooth stress-strain curves of the CuZrAl system at different temperatures;
[0022] Figure 3 It is a smooth stress-strain curve achieved under stress cycle loading before the yield point of the embodiment of the present invention;
[0023] Figure 4 is a graph showing changes in atomic internal stress of a system observed by molecular dynamics under stress cycle loading in an embodiment of the present invention;
[0024] Figure 5 is a diagram showing changes in the Voronoi polyhedron observed by the molecular dynamics method under stress cyclic loading in an embodiment of the present invention;
[0025] Figure 6 is the statistics of cluster activation at different cycle numbers observed by the molecular dynamics method of the embodiment of the present invention;
[0026] Figure 7 It is an intuitive schematic diagram of clusters activated at different times at the 0th and 3rd cycle times observed by molecular dynamics in an embodiment of the invention. DETAILED DESCRIPTION
[0027] The principles and features of the present invention are described below in conjunction with the accompanying drawings. The examples given are only used to explain the present invention and are not used to limit the scope of the present invention.
[0028] like Figure 1 As shown, the atomic mechanism analysis method of stress cycle and fatigue behavior of amorphous alloy comprises the following steps:
[0029] Step 1: Generate an amorphous alloy configuration.
[0030] The amorphous alloy samples were prepared by a molecular dynamics method in a step-by-step cooling manner. First, a crystalline sample was prepared, and the temperature was raised to above the melting temperature T. The high-temperature equilibrium state was obtained by relaxing for 2ns at temperature T. Then, the amorphous alloy configurations at different temperatures were obtained by a step-by-step cooling method with a temperature reduction of 50K per step. Taking the ZrCuAl system as an example, the temperature T was 2000K at this time.
[0031] Step 2: Use molecular dynamics method to perform multiple tensile loading on the amorphous alloy to achieve a smooth stress-strain curve.
[0032] Based on the amorphous alloy configurations at different temperatures obtained in step 1, the amorphous alloy is subjected to tensile loading using a molecular dynamics method; since the amorphous alloy system prepared by the molecular dynamics method is greatly different from the amorphous alloy system prepared in the laboratory in terms of spatial scale, the stress-strain curve obtained by tensile loading once fluctuates greatly; different velocity distributions are used for the same amorphous alloy configuration to achieve 50-100 times of stress-strain measurements to obtain a smooth stress-strain curve; based on the smooth tensile loading stress-strain curve, the elastic stage, yield stage and yield stress value of the amorphous alloy sample during tensile loading are determined;
[0033] Step 3: Apply stress cyclic loading to the amorphous alloy.
[0034] Based on the amorphous alloy configurations at different temperatures obtained in step 1, stress cyclic loading is performed by applying different stress amplitudes; the stress amplitude is determined according to the yield stress value obtained in step 2, and stress amplitudes of different sizes lower than the yield stress are selected; to ensure the smoothness of the curve, stress cyclic loading is applied multiple times to construct different velocity distributions for the same configuration, and finally averaged;
[0035] Step 4: Analyze the atomic mechanism of stress cycle and fatigue behavior using the smooth stress cycle loading curve obtained in step 3.
[0036] Quantify the stress cyclic loading curve of amorphous alloys, make qualitative comparison with the stress cyclic loading curve obtained by experiment, and then explore the atomic mechanism of stress cyclic loading and fatigue behavior; observe the atomic response during the loading process, calculate the local structural characteristics during the loading process, and explore the structural evolution and dynamic evolution during stress cyclic loading, such as the Voronoi polyhedron calculated by the Voronoi method.
[0037] The atomic mechanism analysis method of stress cycle and fatigue behavior of an amorphous alloy described above can realize a smooth curve of stress cycle loading based on the molecular dynamics method, and the experimental results can be compared with the stress cycle loading curve measured in the laboratory; at the same time, it has an advantage that cannot be achieved in laboratory stress cycle loading, which is that the internal mechanism of stress cycle loading can be more accurately explored within the atomic scale. Stress cycle loading is a thermomechanical coupling excitation of amorphous alloys. With different stress amplitudes, amorphous alloys can achieve evolution in two different directions of aging and rejuvenation, thereby regulating the physical and mechanical properties of amorphous alloys. Aging or rejuvenation regulation of amorphous alloy materials can be achieved in molecular dynamics, which can further explore the internal mechanism of aging or rejuvenation of amorphous alloys. The present invention is only applied to amorphous alloy materials, but it can be applied to different materials with potential functions in molecular dynamics.
[0038] In the step 1, the present invention adopts a molecular dynamics method to achieve the preparation of amorphous alloys by step-by-step cooling, which facilitates the preservation of stable configurations at different temperatures.
[0039] Both step 2 and step 3 involve using different velocity distributions for the same amorphous alloy configuration. This is because there is a difference in the spatial scale between the molecular dynamics method and the experiment, so it is necessary to use the molecular dynamics method for multiple measurements. In step 2, the stress-strain curve of the specific amorphous alloy system is determined, thereby determining the elastic stage, yield stage and specific yield point values of the amorphous alloy simulation sample, such as Figure 2 In step 3, before the yield point, the amorphous alloy is subjected to stress cyclic loading with different maximum stress amplitudes. In this process, multiple loadings with different velocity distributions are applied to the same configuration to obtain a smooth cyclic loading curve, as shown in Figure 3 shown.
[0040] On the basis of obtaining the smooth stress cycle loading curve, the magnitude of atomic local stress is specifically calculated under different stress cycle conditions, and the stress evolution under different stress cycle loading conditions is observed, such as Figure 4 shown.
[0041] Since the structure of amorphous alloys is in a disordered state, defects in the crystal such as dislocations and interfaces cannot be used to describe the amorphous structure. Therefore, in the present invention, the Voronoi polyhedron method is used to characterize the amorphous alloy structure. The specific definition of the Voronoi polyhedron is that the connecting lines of the central atom and all its nearest neighbor atoms are perpendicular bisectors, and the polyhedron formed by all perpendicular bisectors is called the Voronoi polyhedron. This polyhedron can reflect the local structure and its symmetry structure. For example, <0 0 12 0> represents that the number of triangles in the Voronoi polyhedron is 0, the number of quadrilaterals is 0, the number of pentagons is 12, and the number of hexagons is 0; this polyhedron has the highest quintic symmetry. On the basis of obtaining the smooth stress cyclic loading curve, the Voronoi polyhedron method is used to analyze the amorphous structure under different cyclic conditions, such as Figure 5 shown.
[0042] According to different systems, different temperatures, different maximum stress loading amplitudes and different stress loading frequencies, the regular changes of amorphous alloy structure and dynamic activation are observed, such as Figure 6 , Figure 7 As shown, this provides a parameter range for experimental stress cyclic loading or fatigue, and further provides theoretical guidance for the state regulation of amorphous alloys.
[0043] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principle of the present invention should be included in the protection scope of the present invention.
Claims
1. An atomic mechanism analysis method for stress cycling and fatigue behavior of an amorphous alloy, characterized in that: The following steps are involved: Step 1: Generate amorphous alloy configuration: The amorphous alloy samples were prepared by a molecular dynamics method in a step-by-step cooling method. Specifically, a crystalline sample was first prepared, the temperature was raised to above the melting temperature T, and a high-temperature equilibrium state was obtained by relaxing for 2ns at the temperature T. Then, the amorphous alloy configurations at different temperatures were obtained by a step-by-step cooling method with a temperature reduction of 50K per step. Step 2: Use molecular dynamics method to perform multiple tensile loading on the amorphous alloy to achieve a smooth stress-strain curve: Based on the amorphous alloy configurations at different temperatures obtained in step 1, the amorphous alloy is subjected to tensile loading using a molecular dynamics method; different velocity distributions are used for the same amorphous alloy configuration to achieve 50-100 times of stress-strain measurement to obtain a smooth stress-strain curve; based on the smooth tensile loading stress-strain curve, the elastic stage, yield stage and yield stress value of the amorphous alloy sample during tensile loading are determined; Step 3: Apply stress cyclic loading to the amorphous alloy: Based on the amorphous alloy configurations at different temperatures obtained in step 1, stress cyclic loading is performed by applying different stress amplitudes; to ensure the smoothness of the curve, stress cyclic loading is applied multiple times with different velocity distributions constructed for the same configuration, and finally the results are averaged; Step 4: Use the smooth stress cycle loading curve obtained in step 3 to analyze the atomic mechanism of stress cycle and fatigue behavior: Quantify the stress cyclic loading curve of amorphous alloys and make qualitative comparison with the stress cyclic loading curve obtained by experiment, so as to explore the atomic mechanism of stress cyclic loading and fatigue behavior; Observe the atomic response during the loading process, calculate the local structural characteristics during the loading process, and explore the structural evolution and dynamic evolution during stress cyclic loading.
2. The atomic mechanism analysis method for stress cycling and fatigue behavior of amorphous alloys according to claim 1, characterized in that: In the step 1, the melting temperature T of the amorphous alloy sample is 2000-3000K.
3. The atomic mechanism analysis method for stress cycle and fatigue behavior of amorphous alloys according to claim 1, characterized in that: In the step 2, the amorphous alloy structure is characterized by using a Voronoi polyhedron method, wherein the Voronoi polyhedron is a polyhedron formed by connecting the connecting lines of the central atom and all its nearest neighbor atoms with perpendicular bisectors and all the perpendicular bisectors.
4. The atomic mechanism analysis method for stress cycling and fatigue behavior of amorphous alloys according to claim 1, characterized in that: In the step three, the stress amplitude of the stress cycle loading is determined by the yield stress value obtained in the step two, and stress amplitudes of different sizes lower than the yield stress are selected.
5. The atomic mechanism analysis method for stress cycle and fatigue behavior of amorphous alloys according to any one of claims 1 to 4, characterized in that: In the step 4, the activation of clusters at different cycle times is counted to observe the regular changes in the structure and kinetic activation of the amorphous alloy.