Method for describing characteristic vector parameters of amorphous alloy atomic structure

Abstract

The invention belongs to the technical field of molecular dynamics simulation, and particularly relates to a method for describing adaptive center summation vector parameters of amorphous alloy atomic structure characteristics. The method is characterized by comprising the following steps: firstly, generating an amorphous alloy atom configuration, adaptively determining the position of a nearest neighbor atom of each atom, then constructing vector components by taking a central atom as a starting point and the nearest neighbor atom as an end point, summing all vectors to obtain an adaptive central summing vector, and finally evaluating the local structure characteristics of the atoms according to the distribution of vector amplitudes. The method depends on the coordinate positions of atoms, each atom is endowed with a corresponding center summation vector parameter, the nearest neighbor atom of each atom can be adaptively identified, and the symmetry degree of different atomic clusters is evaluated by calculating the amplitude of the adaptive center summation vector parameters of the center atoms of different clusters. The method is used for describing atomic configuration characteristics generated in molecular dynamics simulation. And an effective means is provided for atomic structure description and performance optimization of the amorphous alloy.

Description

Technical Field

[0001] The invention belongs to the technical field of molecular dynamics simulation, and in particular relates to a method for describing adaptive central sum vector parameters of amorphous alloy atomic structure characteristics. Background Art

[0002] Amorphous alloys, also known as metallic glasses, are a class of alloy materials characterized by long-range disordered structures. They are usually prepared by rapidly cooling molten metals to avoid crystal growth and the formation of a conventional crystalline structure. This rapid cooling process does not allow enough time for the atoms in the alloy to arrange themselves into an ordered crystalline structure, resulting in a random arrangement state similar to a liquid, but with the mechanical properties of a solid.

[0003] The description of the atomic structure of amorphous alloys is indeed a challenge in materials science. The atomic structure of crystalline materials can be described by crystallographic methods such as lattice lattices, which rely on the periodicity of atomic arrangements. Amorphous alloys do not have this periodicity and lack similar universal parameterization methods to describe their structure. The local structure of amorphous alloys contains a variety of different atomic clusters and irregular arrangements, which makes it difficult to give a unified and accurate description of the atomic structure of amorphous alloys. The relationship between the structure of amorphous alloys and their properties is not as clear as that of crystalline materials, which makes it more difficult to predict and optimize performance through structure.

[0004] The local structural characteristics of existing amorphous alloys can be described by local structural entropy, which can reflect the degree of disorder of the local structure in which the atoms are located. However, this method is computationally cumbersome and cannot intuitively reflect the symmetry of the local atomic structure. Summary of the invention

[0005] The purpose of the present invention is to avoid the shortcomings of the prior art and provide a method for describing the characteristic vector parameters of the atomic structure of an amorphous alloy. The method can quickly reveal the local characteristics of atoms in the amorphous alloy and help to distinguish atoms in different crystals and amorphous structures, thereby solving the problems in the prior art.

[0006] To achieve the above object, the technical solution adopted by the present invention is a method for describing the characteristic vector parameters of the atomic structure of an amorphous alloy, comprising the following steps: Step 1: Generate the atomic configuration of amorphous alloy. Through molecular dynamics simulation, the alloy melt is rapidly cooled to obtain the atomic configuration of the amorphous alloy, and the three-dimensional coordinates of all atoms are recorded; Step 2: Adaptively determine the nearest neighbor atom position of each central atom. Each atom in the generated amorphous alloy atomic configuration is taken as the central atom, and multiple mid-vertical planes are used to separate the central atom and its closer atoms respectively. Different mid-vertical planes intersect to form a minimum polyhedron enclosing the central atom; each face of the polyhedron corresponds to a nearest neighbor atom, so as to realize adaptive determination of the nearest neighbor atom position of each central atom; Step 3: construct vector components with the central atom as the starting point and the nearest neighbor atom as the end point, and sum all vectors to obtain the adaptive central sum vector. Starting from each central atom, each nearest neighbor atom i Construct vector for end point , and sum all vectors to construct the adaptive central sum vector of the central atom ; where N is the number of nearest neighbor atoms of the central atom, i is the number of the nearest neighbor atom, and its value is 1~ N , the adaptive central sum vector is denoted by ; Since each atom can be used as a central atom, the adaptive central sum vector of all atoms in the system can be obtained ; Step 4: Use the distribution of the vector amplitude to evaluate the local structural characteristics of the atom. The obtained adaptive central sum vector is used as the characteristic vector parameter describing the atomic structure of the amorphous alloy. According to the amplitude of the obtained adaptive central sum vector, the symmetry and local structural characteristics of different atomic clusters are statistically quantified. The smaller the amplitude distribution of the vector, the higher the symmetry of the cluster where the atom is located and the lower the degree of disorder of its local structure, that is, the local structural characteristics of the atom are evaluated.

[0007] The adaptive central sum vector described in step three is used to describe the local characteristics of the grain boundaries of polycrystalline and crystal-amorphous composite structures; the amplitude of the adaptive central sum vector is used to distinguish the amorphous-amorphous boundaries between different amorphous particles.

[0008] The smaller the amplitude distribution of the vector described in step 4, the smaller the components of the vector In the summation process, they cancel each other out due to the symmetry of the cluster, that is, the higher the symmetry of the cluster the atom is in.

[0009] The beneficial effects of the present invention are as follows: the present invention provides a method for describing the characteristic vector parameters of the atomic structure of an amorphous alloy, which does not rely on a preset lattice structure or a fixed coordinate system, but only relies on the coordinate position of the atom. Each atom is assigned a corresponding central sum vector parameter, which can adaptively identify the nearest neighbor atoms of each atom, and by calculating the amplitude of the adaptive central sum vector parameters of the central atoms of different clusters, the degree of symmetry of different atomic clusters is statistically evaluated, which is suitable for describing the atomic configuration characteristics generated in molecular dynamics simulations. BRIEF DESCRIPTION OF THE DRAWINGS

[0010] Figure 1 It is an implementation flow chart of the present invention; Figure 2 is a configuration diagram of a CuZr binary amorphous alloy in a molecular dynamics simulation system of an embodiment of the present invention; Figure 3 is a schematic diagram of the nearest neighbor atoms of the central atom obtained in an embodiment of the present invention; Figure 4 Schematic diagram of adaptive central sum vectors of different atomic clusters and their corresponding central atoms according to an embodiment of the present invention; Figure 5 is a schematic diagram of the distribution of the adaptive central sum vector amplitudes of central atoms of different atomic clusters in the atomic system of an embodiment of the present invention; Figure 6 It is a schematic diagram of the effect of the embodiment of the present invention on the atomic structure recognition of nano amorphous alloy; Figure 7 It is a schematic diagram of the structural recognition effect of polycrystalline and amorphous-polycrystalline composite materials according to an embodiment of the present invention. DETAILED DESCRIPTION

[0011] 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.

[0012] like Figure 1 As shown, the method for describing the characteristic vector parameters of the atomic structure of an amorphous alloy comprises the following steps: Step 1: Generate the atomic configuration of amorphous alloy. Through molecular dynamics simulation, the alloy melt is rapidly cooled to obtain the atomic configuration of the amorphous alloy, and the three-dimensional coordinates of all atoms are recorded; Step 2: Adaptively determine the nearest neighbor atom position of each central atom. Each atom in the generated amorphous alloy atomic configuration is taken as the central atom, and multiple mid-vertical planes are used to separate the central atom and its closer atoms respectively. Different mid-vertical planes intersect to form a minimum polyhedron enclosing the central atom; each face of the polyhedron corresponds to a nearest neighbor atom, so as to realize adaptive determination of the nearest neighbor atom position of each central atom; Step 3: construct vector components with the central atom as the starting point and the nearest neighbor atom as the end point, and sum all vectors to obtain the adaptive central sum vector. Starting from each central atom, each nearest neighbor atom i Draw a vector for the end point , and sum all vectors to construct the adaptive central sum vector of the central atom ; where N is the number of nearest neighbor atoms of the central atom, i is the number of the nearest neighbor atom, and its value is 1~ N , the adaptive central sum vector is denoted by ; Since each atom can be used as a central atom, the adaptive central sum vector of all atoms in the system can be obtained ; Step 4: Use the distribution of the vector amplitude to evaluate the local structural characteristics of the atom. The obtained adaptive central sum vector is used as the characteristic vector parameter describing the atomic structure of the amorphous alloy. According to the amplitude of the obtained adaptive central sum vector, the symmetry and local structural characteristics of different atomic clusters are quantified in a statistical sense. The smaller the amplitude distribution of the vector, the higher the symmetry of the cluster where the atom is located and the lower the degree of disorder of its local structure, that is, the local structural characteristics of the atom are evaluated.

[0013] The smaller the amplitude distribution of the vector described in step 4, the smaller the components of the vector In the summation process, they cancel each other out due to the symmetry of the cluster, that is, the higher the symmetry of the cluster the atom is in.

[0014] Figure 2 is a configuration diagram of a CuZr binary amorphous alloy in a molecular dynamics simulation system of an embodiment of the present invention; Figure 3 It is a schematic diagram of the nearest neighbor atoms of the central atom obtained in an embodiment of the present invention, and the atom surrounded by the middle polyhedron is the central atom.

[0015] The present invention uses the amorphous alloy atomic configuration prepared by the rapid cooling method in the molecular dynamics simulation. Since the environment of each atom in the amorphous alloy is different, the number and relative position of its nearest neighbor atoms are also different. For each atom in the system, it can be used as a central atom, and multiple mid-vertical planes are used to separate the central atom and its closer atoms respectively, and different mid-vertical planes intersect to form a minimum polyhedron enclosing the central atom. Each face of the polyhedron corresponds to a nearest neighbor atom, so all the nearest neighbor atoms of the central atom are obtained.

[0016] like Figure 4 The central sum vectors of the central atoms of different atomic clusters are shown, which have different amplitudes and directions. The vector distribution characteristics of different atomic cluster structures can be obtained by counting the amplitudes of the adaptive central sum vectors of all atoms in the system. Figure 5 The results show that the central atom of the icosahedral cluster with cluster index <0,0,12,0> has a lower vector amplitude distribution, indicating that in a statistical sense the icosahedral atomic cluster has a higher symmetry than other atomic clusters.

[0017] The calculated amplitude of the adaptive central sum vector can be used to distinguish atoms in different local structures. Figure 6 The figure shows a nano-amorphous alloy composed of multiple amorphous alloy particles. The adaptive center sum vector amplitude distribution can distinguish the amorphous-amorphous interface between different amorphous alloy particles. The present invention shows the effect of the atomic structure recognition of nano-amorphous alloys, where (a) is the nano-amorphous alloy configuration; (b) is a schematic diagram of using the adaptive center sum vector parameter to distinguish different amorphous particles and amorphous-amorphous boundaries.

[0018] Finally, it should be made clear that the adaptive central sum vector in the present invention is mainly used to describe the local atomic structure characteristics in amorphous alloys with different coordination numbers. However, for a crystal structure with a fixed coordination number, the adaptive central sum vector in the present invention can automatically identify its fixed nearest neighbor atoms, so it can also be used directly. For example Figure 7 The present invention has a significant effect on the recognition of polycrystalline and amorphous-polycrystalline composite material structures. Figure 7 (a) is the adaptive center sum vector amplitude distribution of the polycrystal, which can clearly distinguish different grains and their grain boundaries. Figure 7 The more complex crystal-amorphous composite system in (b) can also be applied. This method is suitable for describing the amorphous-amorphous boundary of nano-amorphous alloy system, as well as the grain boundary of polycrystalline and even complex atomic structures such as crystal-amorphous composite structure. The adaptive central sum vector can be used to describe the local characteristics of the grain boundary of polycrystalline and crystal-amorphous composite structure; the amplitude of the adaptive central sum vector can be used to distinguish the amorphous-amorphous boundary between different amorphous particles.

[0019] 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. A method for describing characteristic vector parameters of atomic structure of amorphous alloy, characterized in that: The following steps are involved: Step 1: Generate the atomic configuration of amorphous alloy. Through molecular dynamics simulation, the alloy melt is rapidly cooled to obtain the atomic configuration of the amorphous alloy, and the three-dimensional coordinates of all atoms are recorded; Step 2: Adaptively determine the nearest neighbor atom position of each central atom. Each atom in the generated amorphous alloy atomic configuration is taken as the central atom, and multiple mid-vertical planes are used to separate the central atom and its closer atoms respectively. Different mid-vertical planes intersect to form a minimum polyhedron enclosing the central atom; each face of the polyhedron corresponds to a nearest neighbor atom, so as to realize adaptive determination of the nearest neighbor atom position of each central atom; Step 3, construct vector components with the central atom as the starting point and the nearest neighbor atom as the end point, and sum all vectors to obtain an adaptive central sum vector; Step 4: Use the distribution of the vector amplitude to evaluate the local structural characteristics of the atom. The obtained adaptive central sum vector is used as the characteristic vector parameter describing the atomic structure of the amorphous alloy. According to the amplitude of the obtained adaptive central sum vector, the symmetry and local structural characteristics of different atomic clusters are statistically quantified. The smaller the amplitude distribution of the vector, the higher the symmetry of the cluster where the atom is located and the lower the degree of disorder of its local structure, that is, the local structural characteristics of the atom are evaluated.

2. A method for describing characteristic vector parameters of atomic structure of an amorphous alloy according to claim 1, characterized in that: The step three includes constructing a vector with each central atom as the starting point and each nearest neighbor atom as the end point. , and sum all vectors to construct the adaptive central sum vector of the central atom ;in, N is the number of nearest neighbor atoms of the central atom, i is the number of the nearest neighbor atom, and its value is 1~ N , the adaptive central sum vector is denoted by ; Since each atom can be used as a central atom, the adaptive central sum vector of all atoms in the system can be obtained .

3. A method for describing characteristic vector parameters of atomic structure of an amorphous alloy according to claim 1 or 2, characterized in that: The adaptive central sum vector described in step 3 is used to describe the local characteristics of the grain boundary of the polycrystalline and the crystal-amorphous composite structure; The magnitude of the adaptive central sum vector is applied to distinguish the amorphous-amorphous boundaries between different amorphous grains.

4. A method for describing characteristic vector parameters of atomic structure of an amorphous alloy according to claim 1, characterized in that: The smaller the amplitude distribution of the vector described in step 4, the smaller the components of the vector In the summation process, they cancel each other out due to the symmetry of the cluster, that is, the higher the symmetry of the cluster the atom is in.

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