A method for establishing the relationship between the dimple morphology of the cross-section of a metallic glass and the distribution of flow units

Abstract

The present invention discloses a method for establishing a connection between the dimple morphology of a metallic glass fracture surface and the distribution of flow units. The method mainly quantitatively characterizes and establishes a connection between the dimple morphology distribution of the metallic glass fracture surface and the distribution of flow units. The established relationship between the dimple morphology distribution of the fracture surface and the flow unit distribution will play a role in establishing the relationship between the macroscopic mechanical performance behavior and the microstructure of the metallic glass. The present invention first statistically calculates the dimple morphology distribution of the metallic glass fracture surface, characterizes the distribution of the flow units through the behavior of β relaxation, and compares the change in the σ value that characterizes the degree of discreteness of the dimple morphology distribution with the half-height width FWHM value that characterizes the distribution of the flow units, and obtains that the dimple morphology distribution of the metallic glass fracture surface and the flow unit distribution show a consistent change trend. The σ value that characterizes the dimple morphology distribution of the metallic glass according to the present invention is consistent with the change trend of the half-height width FWHM value that characterizes the distribution of the flow units, that is, the connection between the dimple morphology distribution of the metallic glass fracture surface and the flow unit distribution is established.

Description

Technical Field

[0001] The present invention belongs to the field of establishing a connection between the fracture behavior of metallic glass and its microstructure characteristics, and in particular relates to a method for establishing a connection between the dimple morphology distribution of the fracture surface of metallic glass and the flow unit distribution. Background Art

[0002] In the process of modern materials science research, it is particularly important to establish the relationship between macroscopic mechanical behavior and microstructure. However, due to the long-range disorder in the structure of metallic glass, it is impossible to establish the relationship between microstructure and macroscopic mechanical behavior. With the continuous development of scientific research, some studies have found that the structure of metallic glass is not uniform, but there are some soft areas called flow units that are not "frozen". Therefore, it can be considered that the structure of metallic glass is a densely arranged substrate (hard area) inlaid with some loosely arranged areas (flow units). Since the discovery of flow units, they have been considered as structural defects of metallic glass, and modifying the mechanical properties of metallic glass by regulating flow units has received widespread attention. Studies have shown that flow units are the high-quality generation location of the shear transition zone of the deformation carrier of metallic glass, which indicates that there is a correlation between flow units and the mechanical behavior of metallic glass.

[0003] Although metallic glass has many excellent mechanical properties, its zero plasticity at room temperature is one of the main reasons that hinders its use as a structural material, so plasticizing metallic glass has become the main purpose of studying metallic glass. The dimple morphology size of the fracture surface of the material is inextricably linked to the plastic toughness. Analogous to the correlation between the grain size and the dimple morphology size of the fracture surface in crystalline materials, that is, the smaller the grain size, the smaller the dimple size of the fracture surface. The present invention mainly quantitatively characterizes the distribution of dimple morphology of the fracture surface of metallic glass and the distribution of flow units and establishes a connection. The dimple morphology distribution of the fracture surface and the flow unit distribution established by the present invention will play a role in establishing the relationship between the macroscopic mechanical behavior and the microstructure of metallic glass. Summary of the Invention

[0004] In order to overcome the difficulty in establishing a connection between the macroscopic mechanical behavior and microstructure of metallic glass, the purpose of the present invention is to provide a method for establishing a connection between the dimple morphology distribution on the fracture surface of metallic glass and the distribution of flow units in its microstructure.

[0005] In order to achieve the above-mentioned purpose, the present invention adopts the following technical solutions:

[0006] A method for establishing a relationship between dimple morphology of a metallic glass cross section and flow unit distribution includes the following steps:

[0007] 1) Statistical analysis of dimple morphology distribution on fracture surfaces of metallic glass: metallic glass with a diameter of 2 to 6 mm was prepared by copper mold suction casting; the metallic glass obtained by suction casting was prepared into a column with an aspect ratio of 1 to 2, and both ends of the column were ground flat; the metallic glass column was stretched by a stretching machine at a speed of 0.01 to 0.03 s. -1 The uniaxial compression was carried out at a speed of 100° until the metallic glass column underwent a typical shear fracture at an angle of approximately 45° to the axial direction; a clearly visible dimple distribution diagram of the fracture surface of the metallic glass column was photographed under a scanning electron microscope; the maximum straight line length that can be accommodated inside the dimple was used as a quantitative indicator of the dimple size, and the dimple size was statistically analyzed using this quantitative indicator, and the dimple size and its corresponding number were statistically analyzed in the form of a bar graph to calculate the distribution of the dimple morphology size; the Gauss fitting method was used to fit the dimple morphology size distribution; the results of the Gauss fitting were calculated by the normal distribution parameters X~N(μ,σ 2 ) is characterized in the form of σ, and the dimple morphology size distribution is described by the change of σ value;

[0008] 2) Determination of the flow unit distribution of metallic glass: Dynamic thermomechanical analysis (DTA) was used to determine the loss modulus-temperature correlation curve of the metallic glass. The DTA measurement mode was a single cantilever mode. The DTA heating rate was 1-3 K / min. The DTA heating range was room temperature to 250°C. The β relaxation peak in the loss modulus-temperature curve was fitted using Guass fitting. The half-maximum width (FWHM) of the fitted peak was selected as the parameter for measuring the flow unit distribution.

[0009] 3) By comparing the changes in σ value and half-maximum width (FWHM) value, it can be found that the dimple morphology distribution on the fracture surface of metallic glass shows a consistent change trend with the flow unit distribution.

[0010] The metallic glass system comprises La-Ni-Al.

[0011] In step 1), the aspect ratio of the uniaxially compressed metallic glass column is 1 to 2.

[0012] The uniaxial compression rate in step 1) is 0.01 to 0.03 s -1 .

[0013] The dimple size counted in step 1) is the maximum side length of the dimple.

[0014] In step 1), the normal distribution parameters X~N(μ,σ) are obtained by using Guass fitting for dimple sizes of different sizes. 2 ), the change in dimple morphology distribution is characterized by the change trend of σ value.

[0015] The measurement mode of the dynamic thermomechanical analysis method for measuring the loss modulus-temperature dependence curve in step 2) is the single cantilever mode.

[0016] The heating rate of the dynamic thermomechanical analysis method for measuring the loss modulus-temperature correlation curve in step 2) is 1 to 3 K / min.

[0017] The temperature rise range of the dynamic thermomechanical analysis method for measuring the loss modulus-temperature dependence curve in step 2) is room temperature to 250°C.

[0018] In step 2), the half-maximum width (FWHM) value of the β relaxation peak in the loss modulus-temperature correlation curve is obtained by Guass fitting, and the change trend of the FWHM value is used to characterize the change in the flow unit distribution.

[0019] The present invention has found through research that the changing trend of the σ value characterizing the dimple morphology distribution of metallic glass is consistent with the half-maximum width FWHM value characterizing the flow unit, that is, it can be considered that the connection between the dimple morphology distribution of the metallic glass fracture surface and the flow unit distribution is established. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] Figure 1 The figures are the statistics and fitting diagrams of dimple morphology and size of metallic glasses with different structural states in the present invention.

[0021] Figure 2 The figures are the correlation curves of the loss modulus and temperature of metallic glasses with different structural states and the β relaxation fitting diagrams of the present invention.

[0022] Figure 3 This is a graph showing the changing trends of the σ value and the half-maximum width (FWHM) value of the present invention as the microstructures of different metallic glasses change. DETAILED DESCRIPTION

[0023] The present invention will be further described below with reference to the accompanying drawings and examples.

[0024] Figure 1 This is a histogram of the relationship between dimple size and number. In order to further quantify the distribution of dimple size, Guass fitting is performed on it, as shown in the fitting curve in the figure;

[0025] Figure 2 To normalize the correlation curve of loss modulus and temperature, and to further provide a better quantitative description of the distribution temperature range of β relaxation, a Guass fitting is performed, as shown in the fitted shaded part of the figure;

[0026] Figure 3 For the above Figure 1 and Figure 2The fitted quantitative parameter σ, which characterizes the distribution of dimple morphology, and the quantitative parameter FWHM, which characterizes the distribution of flow units, show the changing trend of the values as the microstructures of different metallic glasses change.

[0027] As-cast La-based metallic glass was selected as a benchmark for comparison. The following steps were used to measure the σ value, which describes the dimple size distribution, and the FWHM value, which measures the half-maximum width of the flow unit distribution.

[0028] A metallic glass with a diameter of 4 mm was prepared by copper mold suction casting. The metallic glass obtained by suction casting was prepared into a column with an aspect ratio of 1, and both ends of the column were polished. The metallic glass column was stretched by a stretching machine at a speed of 0.03 s. -1 The metallic glass column was uniaxially compressed at a speed of 100° until a typical shear fracture occurred at an angle of approximately 45° to the axial direction. A clearly visible dimple distribution diagram of the fracture surface of the metallic glass column was captured under a scanning electron microscope. The maximum straight line length that could be accommodated inside the dimple was used as a quantitative indicator of the dimple size. The dimple size was statistically analyzed using this quantitative indicator, and the dimple size and its corresponding number were statistically analyzed in the form of a bar graph to determine the distribution of dimple morphology. The dimple size distribution was fitted using Gauss fitting. The result of the Gauss fitting was expressed as a normal distribution as X~N(11.46,5.89 2 ), that is, the σ value of the cast La-based metallic glass is 5.89;

[0029] The dynamic thermomechanical analysis method was used to determine the loss modulus-temperature correlation curve of the metallic glass; the measurement mode of the dynamic thermomechanical analysis method was the single cantilever mode; the heating rate of the dynamic thermomechanical analysis method was 3K / min; the heating range of the dynamic thermomechanical analysis method was room temperature to 250°C; the β relaxation peak in the loss modulus-temperature curve was fitted using the Guass fitting method; the half-height width (FWHM) value of the fitted peak was selected as the parameter to measure the flow unit distribution, and the half-height width (FWHM) value of the cast La-based metallic glass was obtained to be 41.7.

[0030] Example 1

[0031] La-based metallic glass after 10 cycles of low-temperature thermal cycling for 1 minute (CTC1) was selected as the test sample to measure the σ value describing the dimple morphology size distribution and the FWHM value measuring the half-maximum width of the flow unit distribution.

[0032] A metallic glass with a diameter of 4 mm was prepared by copper mold suction casting. The metallic glass obtained by suction casting was prepared into a column with an aspect ratio of 1, and both ends of the column were polished. The metallic glass column was stretched by a stretching machine at a speed of 0.03 s. -1The metallic glass column was uniaxially compressed at a speed of 100° until a typical shear fracture occurred at an angle of approximately 45° to the axial direction. A clearly visible dimple distribution diagram of the fracture surface of the metallic glass column was captured under a scanning electron microscope. The maximum straight line length that could be accommodated inside the dimple was used as a quantitative indicator of the dimple size. The dimple size was statistically analyzed using this quantitative indicator, and the dimple size and its corresponding number were statistically analyzed in the form of a bar graph to determine the distribution of dimple morphology. The dimple size distribution was fitted using Gauss fitting. The results of the Gauss fitting were expressed as a normal distribution as X~N(10.23,4.17 2 ), that is, the σ value of the cast La-based metallic glass is 4.17;

[0033] The dynamic thermomechanical analysis method was used to determine the loss modulus-temperature correlation curve of the metallic glass; the measurement mode of the dynamic thermomechanical analysis method was the single cantilever mode; the heating rate of the dynamic thermomechanical analysis method was 3K / min; the heating range of the dynamic thermomechanical analysis method was room temperature to 250°C; the β relaxation peak in the loss modulus-temperature curve was fitted using the Guass fitting method; the half-height width (FWHM) value of the fitted peak was selected as the parameter to measure the flow unit distribution, and the half-height width (FWHM) value of the cast La-based metallic glass was obtained to be 38.4.

[0034] By comparing the changes in σ and FWHM values between CTC1 and cast Figure 3 As shown, it can be obtained that the dimple morphology distribution on the fracture surface of metallic glass and the flow unit distribution show a consistent changing trend. This result shows that the present invention can establish a connection between the dimple morphology distribution on the fracture surface of metallic glass and the flow unit distribution.

[0035] Example 2

[0036] La-based metallic glass after 10 cycles of 2 minutes of low-temperature thermal cycling (CTC2) was selected as the test sample to measure the σ value describing the dimple morphology size distribution and the FWHM value measuring the half-maximum width of the flow unit distribution.

[0037] A metallic glass with a diameter of 4 mm was prepared by copper mold suction casting. The metallic glass obtained by suction casting was prepared into a column with an aspect ratio of 1, and both ends of the column were polished. The metallic glass column was stretched by a stretching machine at a speed of 0.03 s. -1The metallic glass column was uniaxially compressed at a speed of 100° until a typical shear fracture occurred at an angle of approximately 45° to the axial direction. A clearly visible dimple distribution diagram of the fracture surface of the metallic glass column was captured under a scanning electron microscope. The maximum straight line length that could be accommodated inside the dimple was used as a quantitative indicator of the dimple size. The dimple size was statistically analyzed using this quantitative indicator, and the dimple size and its corresponding number were statistically analyzed in the form of a bar graph to determine the distribution of dimple morphology. The dimple size distribution was fitted using Gauss fitting. The result of the Gauss fitting was expressed as a normal distribution X~N(10.78,4.70 2 ), that is, the σ value of the cast La-based metallic glass is 4.70;

[0038] The dynamic thermomechanical analysis method was used to determine the loss modulus-temperature correlation curve of the metallic glass; the measurement mode of the dynamic thermomechanical analysis method was the single cantilever mode; the heating rate of the dynamic thermomechanical analysis method was 3K / min; the heating range of the dynamic thermomechanical analysis method was room temperature to 250°C; the β relaxation peak in the loss modulus-temperature curve was fitted using the Guass fitting method; the half-height width (FWHM) value of the fitted peak was selected as the parameter to measure the flow unit distribution, and the half-height width (FWHM) value of the cast La-based metallic glass was obtained to be 41.4.

[0039] By comparing the changes in σ value and FWHM value of CTC2, cast state and CTC1, the Figure 3 As shown, it can be obtained that the dimple morphology distribution on the fracture surface of metallic glass and the flow unit distribution show a consistent changing trend. This result shows that the present invention can establish a connection between the dimple morphology distribution on the fracture surface of metallic glass and the flow unit distribution.

[0040] Example 3

[0041] La-based metallic glass after 10 cycles of 4 minutes of low-temperature thermal cycling (CTC4) was selected as the test sample to measure the σ value describing the dimple morphology size distribution and the FWHM value measuring the half-maximum width of the flow unit distribution.

[0042] A metallic glass with a diameter of 4 mm was prepared by copper mold suction casting. The metallic glass obtained by suction casting was prepared into a column with an aspect ratio of 1, and both ends of the column were polished. The metallic glass column was stretched by a stretching machine at a speed of 0.03 s. -1The metallic glass column was uniaxially compressed at a speed of 100° until a typical shear fracture occurred at an angle of approximately 45° to the axial direction. A clearly visible dimple distribution diagram of the fracture surface of the metallic glass column was captured under a scanning electron microscope. The maximum straight line length that could be accommodated inside the dimple was used as a quantitative indicator of the dimple size. The dimple size was statistically analyzed using this quantitative indicator, and the dimple size and its corresponding number were statistically analyzed in the form of a bar graph to determine the distribution of dimple morphology. The dimple size distribution was fitted using Gauss fitting. The result of the Gauss fitting was expressed as a normal distribution as X~N(9.37,3.89 2 ), that is, the σ value of the cast La-based metallic glass is 3.89;

[0043] The dynamic thermomechanical analysis method was used to determine the loss modulus-temperature correlation curve of the metallic glass; the measurement mode of the dynamic thermomechanical analysis method was the single cantilever mode; the heating rate of the dynamic thermomechanical analysis method was 3K / min; the heating range of the dynamic thermomechanical analysis method was room temperature to 250°C; the β relaxation peak in the loss modulus-temperature curve was fitted using the Guass fitting method; the half-height width (FWHM) value of the fitted peak was selected as the parameter to measure the flow unit distribution, and the half-height width (FWHM) value of the cast La-based metallic glass was obtained to be 39.9.

[0044] By comparing the σ value and half-maximum width FWHM value of CTC4 with that of cast, CTC1 and CTC2 as shown in Table 1, the changes of σ value and half-maximum width FWHM value are shown in Table 1. Figure 3 As shown, it can be obtained that the dimple morphology distribution on the fracture surface of metallic glass and the flow unit distribution show a consistent changing trend. This result shows that the present invention can establish a connection between the dimple morphology distribution on the fracture surface of metallic glass and the flow unit distribution.

[0045] Table 1 Statistics of σ values and half-maximum width (FWHM) values of metallic glasses with different structural states of the present invention

[0046] Structural Status <![CDATA[Normal distribution \(X\sim N(\mu,\sigma 2 )]]> Full width at half maximum (FWHM) Cast <![CDATA[X~N(11.46,5.89 2 )]]> 41.7 CTC1 <![CDATA[X~N(10.23,4.17 2 )]]> 38.4 CTC2 <![CDATA[X~N(10.78,4.70 2 )]]> 41.4 CTC4 <![CDATA[X~N(9.37,3.89 2 )]]> 39.9

Claims

1. A method for establishing a relationship between dimple morphology and flow unit distribution in a metallic glass cross section, characterized in that: The following steps are involved: 1) Statistical analysis of dimple morphology distribution on fracture surfaces of metallic glass: metallic glass with a diameter of 2 to 6 mm was prepared by copper mold suction casting; the metallic glass obtained by suction casting was prepared into a column with an aspect ratio of 1 to 2, and both ends of the column were ground flat; the metallic glass column was stretched by a stretching machine at a speed of 0.01 to 0.03 s. -1 The uniaxial compression was carried out at a speed of 100° until the metallic glass column underwent a typical shear fracture at an angle of 45° to the axial direction. A clearly visible dimple distribution diagram of the fracture surface of the metallic glass column was photographed under a scanning electron microscope. The maximum straight line length that could be accommodated inside the dimple was used as a quantitative indicator of the dimple size. The dimple size was statistically analyzed using this quantitative indicator, and the dimple size and its corresponding number were statistically analyzed in the form of a bar graph to determine the distribution of dimple morphology. The dimple size distribution was fitted using the Gauss fitting method. The results of the Gauss fitting were calculated by the normal distribution parameters X~N(μ,σ 2 ) is characterized in the form of σ, and the dimple morphology size distribution is described by the change of σ value; 2) Determination of the flow unit distribution of metallic glass: Dynamic thermomechanical analysis (DTA) was used to determine the loss modulus-temperature correlation curve of the metallic glass. The DTA measurement mode was a single cantilever mode. The DTA heating rate was 1-3 K / min. The DTA heating range was from room temperature to 250°C. The β relaxation peak in the loss modulus-temperature curve was fitted using Guass fitting. The half-maximum width (FWHM) of the fitted peak was selected as the parameter for measuring the flow unit distribution. 3) By comparing the changes in σ value and half-maximum width (FWHM) value, it can be found that the dimple morphology distribution on the fracture surface of metallic glass shows a consistent change trend with the flow unit distribution.

2. The method for establishing a relationship between dimple morphology and flow unit distribution in a metallic glass cross section according to claim 1, characterized in that: The metallic glass comprises La-Ni-Al.

3. The method for establishing a relationship between dimple morphology and flow unit distribution in a metallic glass cross section according to claim 1, characterized in that: In step 1), the aspect ratio of the uniaxially compressed metallic glass column is 1 to 2.

4. The method for establishing a relationship between dimple morphology and flow unit distribution in a metallic glass cross section according to claim 1, characterized in that: The uniaxial compression rate in step 1) is 0.01 to 0.03 s -1 .

5. The method for establishing a relationship between dimple morphology and flow unit distribution in a metallic glass cross section according to claim 1, characterized in that: The dimple size counted in step 1) is the maximum side length of the dimple.

6. The method for establishing a relationship between dimple morphology and flow unit distribution in a metallic glass cross section according to claim 1, characterized in that: In step 1), the normal distribution parameters X~N(μ,σ) are obtained by using Guass fitting for dimple sizes of different sizes. 2 ), the change in dimple morphology distribution is characterized by the change trend of σ value.

7. The method for establishing a relationship between dimple morphology and flow unit distribution in a metallic glass cross section according to claim 1, characterized in that: The measurement mode of the dynamic thermomechanical analysis method for measuring the loss modulus-temperature dependence curve in step 2) is the single cantilever mode.

8. The method for establishing a relationship between dimple morphology and flow unit distribution in a metallic glass cross section according to claim 1, characterized in that: The heating rate of the dynamic thermomechanical analysis method for measuring the loss modulus-temperature correlation curve in step 2) is 1 to 3 K / min.

9. The method for establishing a relationship between dimple morphology and flow unit distribution in a metallic glass cross section according to claim 1, characterized in that: The temperature range of the dynamic thermomechanical analysis method for measuring the loss modulus-temperature dependence curve in step 2) is from room temperature to 250°C.

10. The method for establishing a relationship between dimple morphology and flow unit distribution in a metallic glass cross section according to claim 1, characterized in that: In step 2), the half-maximum width (FWHM) value of the β relaxation peak in the loss modulus-temperature correlation curve is obtained by Guass fitting, and the change trend of the FWHM value is used to characterize the change in the flow unit distribution.

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