A method for classifying as-cast precipitates alpha and beta-aluminum-iron-manganese-silicon phases in an aluminum alloy

Abstract

The application discloses a method for distinguishing the alpha and beta-AlFeMnSi phase types in the as-cast precipitated phase in an aluminum alloy without precipitated phase component detection. A scanning electron microscope (SEM) is used to observe the microstructure of the as-cast or soaking-state aluminum alloy ingot, and according to the gray histogram in the SEM picture, the alloy matrix and the precipitated phase are separated to obtain the maximum length Lmax and the maximum width Wmax of each precipitated phase and the precipitated area S. The Lmax and Wmax ratio of each precipitated phase is calculated. According to the Lmax / Wmax ratio distribution law, the critical ratio k of the alpha and beta-AlFeMnSi phases is determined, wherein the precipitated phase with a ratio of 1.0-k is the alpha-AlFeMnSi phase, and the precipitated phase with a Lmax / Wmax ratio greater than k is the beta-AlFeMnSi phase. Through the geometric classification method, the number of common as-cast precipitated phases alpha and beta-AlFeMnSi in the aluminum alloy can be quickly detected. The experimental cost can be effectively reduced, and the distinguishing efficiency of the alpha and beta-AlFeMnSi phases in the aluminum alloy can be greatly improved. Especially for large-scale sample data with a number of more than 1000, the AlFeMnSi phase types can be quickly and accurately distinguished, and the experimental data can be processed in batches.

Description

Technical Field

[0001] This invention relates to the field of aluminum alloy materials, and specifically to a method for distinguishing the types and quantities of α-AlFeMnSi phases in cast precipitates of aluminum alloys without the need for precipitate composition detection. Background Technology

[0002] Aluminum alloys have become a preferred material for new energy vehicle manufacturing due to their excellent formability, corrosion resistance, and moderate alloy strength. Their application in automotive materials has expanded from traditional body panels to various aspects of body structural profiles, leading automakers to have higher requirements for alloy performance. Simultaneously, driven by environmental protection concepts such as energy conservation and emission reduction, aluminum alloy manufacturers are gradually replacing high-energy-consuming electrolytic aluminum with low-energy-consumption recycled aluminum as a raw material for aluminum alloy production. However, recycled aluminum has a complex composition, introducing more impurity elements as a raw material for alloy production. Since aluminum alloy performance is significantly affected by alloy composition, the increase in impurity elements poses many challenges to ensuring alloy performance. In particular, the increase in the content of Fe, a major impurity element in aluminum alloys, leads to the formation of coarse Fe-rich phases in the alloy matrix, reducing alloy performance. In industrial production, Mn is usually added to the alloy to control the negative impact of Fe impurity elements on alloy performance. The addition of Mn causes a large amount of AlFeMnSi phase to precipitate in the matrix during the casting process. Among them, the long needle-like and lamellar β-AlFeMnSi phases with poor deformability have a significant negative impact on alloy performance. In alloy production, a homogenization process is used to transform the coarse β-AlFeMnSi phase in the alloy matrix into smaller, more deformable granular and Chinese character-shaped α-AlFeMnSi phases, thereby improving alloy properties. The content of α and β-AlFeMnSi phases in the matrix of as-cast and homogenized alloys has become one of the important data for evaluating the properties of as-cast alloys and the homogenization process. Existing research uses energy dispersive spectroscopy (EDS) compositional analysis on individual AlFeMnSi phases, classifying them into α or β-AlFeMnSi phases based on the (Fe+Mn) / Si atomic ratio. Phases with a (Fe+Mn) / Si atomic ratio greater than 1.5 are classified as α-AlFeMnSi phases, while those with a ratio less than 1.5 are classified as β-AlFeMnSi phases. While EDS (Enhanced Sequencing Data) methods can accurately distinguish individual AlFeMnSi phase types, they suffer from low efficiency, high cost, and the inability to batch-count and classify the quantity and type of AlFeMnSi phases when distinguishing multiple AlFeMnSi phases (more than 1000). Therefore, aluminum alloy manufacturers need a more efficient, convenient, and cost-effective technique for batch-counting and classifying AlFeMnSi phases to assess alloy ingot quality and aid in the development of homogenization processes. Summary of the Invention

[0003] Therefore, this invention addresses the problems of low efficiency and high cost in the classification technology of AlFeMnSi phase in cast and homogeneous aluminum alloy matrix, and provides a technical method that can quickly quantify and detect AlFeMnSi phase without additional EDS precipitate composition.

[0004] The technical solution of this invention is: a method for classifying α- and β-AlFeMnSi phases in as-cast precipitates of aluminum alloys, the method comprising the following steps:

[0005] (1) The microstructure of the aluminum alloy sample was observed using a scanning electron microscope (SEM).

[0006] (2) Using image processing methods, the alloy matrix and precipitates in the SEM image are separated based on the color grayscale difference between the aluminum alloy matrix and the precipitates;

[0007] Digital image processing methods were used to measure the maximum length Lmax, maximum width Wmax, and the sum of precipitation areas S of corresponding particle sizes for each precipitated phase in batches, and the Lmax / Wmax ratio of each precipitated phase was calculated. Then, a bar chart of precipitation area distribution for precipitated phases with different Lmax / Wmax ratios was plotted with the Lmax / Wmax ratio as the x-axis and the sum of precipitation areas S as the y-axis, and the peak precipitation area intervals of α and β-AlFeMnSi phases were identified from the chart.

[0008] (3) The Lmax / Wmax ratio in the distribution histogram has two peak positions. The distribution of this peak is described by a normal distribution. The boundary position of the two peaks is the boundary point of the length and width ratio of α-AlFeMnSi and β-AlFeMnSi, and the critical length and width ratio k of the peak is determined. The particles to the left of the boundary point represent the particles with an Lmax / Wmax ratio of 1.0-k, which is the peak interval of α-AlFeMnSi phase precipitation. The particles with an Lmax / Wmax ratio greater than k to the right of the boundary point represent the peak interval of β-AlFeMnSi phase precipitation.

[0009] According to the classification method of cast precipitates α and β-AlFeMnSi phases in aluminum alloys of the present invention, preferably, the SEM image capture magnification in step (1) is 200-500x. This magnification ensures that the number of precipitate samples in the aluminum alloy matrix in the scanned image is large, and the morphology and size are moderate, which is convenient for large-scale accurate statistics.

[0010] According to the present invention, a method for classifying as-cast precipitates α and β-AlFeMnSi phases in aluminum alloys, preferably, the separation of alloy matrix and precipitates in SEM images in step (2) refers to extracting the grayscale values ​​of the SEM images, drawing a grayscale histogram, finding the grayscale thresholds of the aluminum alloy matrix and the second phase, and separating the aluminum alloy matrix and the second phase according to the thresholds.

[0011] Furthermore, in step (2), the aluminum alloy matrix in the SEM image is grayish-black, and the second phase is grayish-white.

[0012] According to the classification method of cast precipitates α and β-AlFeMnSi phases in aluminum alloys of the present invention, preferably, the number of statistical samples of precipitate particles in step (2) is greater than 1000.

[0013] According to the classification method of cast precipitates α and β-AlFeMnSi phases in aluminum alloys of the present invention, preferably, before step (3), after gradually screening and removing the influence of fine dot-shaped precipitates with precipitate area S that meet the sample requirements on the experimental results, the two peak positions of the Lmax / Wmax ratio in the distribution histogram are observed.

[0014] Furthermore, the fine dot-like precipitates have a precipitation area of ​​less than 1.0 μm. 2 Fine granular precipitates.

[0015] Due to the limited resolution of scanning electron microscopes, 1µm 2 It is difficult to determine its aspect ratio, and the phase influence mechanical properties of AlFeMnSi are mainly 1µm. 2 The above particles were therefore filtered out, with particles having a precipitation area of ​​less than 1.0 μm being removed. 2 The fine, particulate precipitate phase significantly improves the accuracy of this classification method; simultaneously, 10µm 2 The particles mentioned above are all formed during the solidification process and are difficult to control through heat treatment. Therefore, particles of 10 μm or less are generally not considered in practical analysis. 2 The above particles.

[0016] Because EDS (Electronic Deposition Analysis) is inefficient and costly in distinguishing AlFeMnSi precipitates, this invention does not perform compositional analysis on the AlFeMnSi precipitates. Instead, it distinguishes between α- and β-AlFeMnSi phases by measuring the maximum length and width of the precipitates and using the ratio of their maximum length to width. The main principle of this classification method is the significant difference in morphology between the α- and β-AlFeMnSi phases. α-AlFeMnSi phases often exhibit granular, short rod-like, or Chinese character-shaped morphologies with small aspect ratios, while β-AlFeMnSi phases often exhibit long needle-like or lamellar morphologies with larger aspect ratios. If the aspect ratio distribution range and boundary point of the α- and β-AlFeMnSi phases can be accurately located, their types can be precisely distinguished based on their aspect ratios.

[0017] Beneficial effects:

[0018] This invention addresses the problems of low efficiency and high cost in the classification technology of AlFeMnSi phase in cast and homogeneous aluminum alloy matrix. Based on the large difference in morphology between α-AlFeMnSi phase, the phase type is analyzed by comparing the length-width ratio geometric factor region of AlFeMnSi phase, without the need for additional EDS precipitation phase composition, and it is a technical method that can quickly and quantitatively detect AlFeMnSi phase.

[0019] This invention distinguishes between α-AlFeMnSi phases by the aspect ratio of the precipitated phase morphology, thus eliminating the need for composition analysis, effectively improving detection efficiency and reducing testing costs. It is particularly beneficial for large-scale statistical analysis of the types, quantities, and precipitation areas of AlFeMnSi phases in aluminum alloy matrices. It provides effective assistance in evaluating the quality of aluminum alloy ingots and developing homogenization processes. Attached Figure Description

[0020] Figure 1 This is a schematic diagram of the separation and measurement of the matrix and precipitates in the microstructure of cast aluminum alloy using SEM. (a) Matrix SEM, (b) Separation of precipitates, (c) Schematic diagram of precipitate measurement.

[0021] Figure 2 The distribution of precipitation area for different aspect ratios is shown in the diagram. (a) No deletions, (b) Deletions of areas smaller than 0.6 μm are shown. 2 (c) Delete particles smaller than 0.8μm 2 (d) Delete particles smaller than 1.0 μm 2 . Detailed Implementation

[0022] The operation process of this invention is as follows:

[0023] 1. Observation of alloy microstructure

[0024] The microstructure of aluminum alloy samples was observed using scanning electron microscopy (SEM), with SEM images taken at magnifications of 200-500x.

[0025] 2. Classification of α- and β-AlFeMnSi

[0026] Grayscale values ​​were extracted from SEM images, and grayscale histograms were plotted to identify the grayscale thresholds for the aluminum alloy matrix and the second phase. The aluminum alloy matrix and the second phase were then separated based on these thresholds. In the SEM images, the aluminum alloy matrix appears grayish-black, and the second phase appears grayish-white. Digital image processing methods were used to batch measure the maximum length L of each precipitated phase. max Maximum width W max Calculate the sum of precipitation areas S of particles of corresponding sizes, and calculate the precipitation phase L for each phase. max / W max Ratio (attached) Figure 1 (As shown). Then, with the precipitated phase L max / Wmax The ratio is used as the x-axis, and the sum of the precipitated areas S is used as the y-axis. Plot different L values. max / W max A histogram of precipitation area distribution of ratio precipitates was used to identify the peak precipitation area intervals of α-AlFeMnSi phases (see attached diagram). Figure 2 As shown, the number of precipitated phase particles in the sample is greater than 1000. Particles with a precipitation area S less than 0.6 μm are removed through stepwise screening. 2 0.8μm 2 and 1.0μm 2 After considering the effect of fine dot-like precipitation on the experimental results, it can be seen from the figure that L max / W max The ratio has two peak positions, and the distribution of these peaks is described using a normal distribution. The boundary between the two peaks is the point where the length and width of α-AlFeMnSi and β-AlFeMnSi are separated. Figure 2 The aspect ratio is used as the dividing point, where the left side of the dividing point represents L. max / W max The particles with a ratio of 1.0-k represent the α-AlFeMnSi phase precipitation peak range and the right-side L. max / W max Particles with an aspect ratio greater than k represent the peak precipitation range of the β-AlFeMnSi phase, with a critical aspect ratio k of 2.7. That is, the aspect ratio of the precipitated phase is 1.0 < L. max / W max <k represents the α-AlFeMnSi phase, L max / W max >k represents the β-AlFeMnSi phase.

[0027] After homogenization using commercial 6000 series aluminum alloy cast rods, the precipitates in the matrix were analyzed by EDS using scanning electron microscopy, and the accuracy of the geometric classification method was verified by combining the aspect ratio values ​​(precipitate detection data are listed in Table 1).

[0028] Example 1:

[0029] The composition of precipitate 1 is 78.09% Al, 4.50% Fe, 7.82% Mn, and 7.88% Si (atomic percentage), with an atomic ratio of (Fe+Mn) / Si of 1.56. Based on the composition analysis, the precipitate is identified as an α-AlFeMnSi phase, with an aspect ratio of 1.64. The classification based on this aspect ratio confirms the correctness of the α-AlFeMnSi phase classification.

[0030] Example 2:

[0031] The composition of precipitate No. 2 is 84.06% Al, 3.36% Fe, 4.09% Mn, and 7.04% Si, with an atomic ratio of (Fe+Mn) / Si of 1.06. Based on the composition analysis, the precipitate is identified as a β-AlFeMnSi phase, with an aspect ratio of 3.54. Therefore, the phase is correctly classified as β-AlFeMnSi.

[0032] Example 3:

[0033] The composition of precipitate No. 3 is 89.07% Al, 1.76% Fe, 2.05% Mn, and 4.95% Si, with an atomic ratio of (Fe+Mn) / Si of 0.77. Based on the composition analysis, the precipitate is identified as a β-AlFeMnSi phase, with an aspect ratio of 8.06. The classification based on this aspect ratio confirms the correctness of the β-AlFeMnSi phase classification.

[0034] Example 4:

[0035] The composition of precipitate No. 4 is 86.13% Al, 3.03% Fe, 3.05% Mn, and 6.01% Si, with an atomic ratio of (Fe+Mn) / Si of 1.02. Based on the composition analysis, the precipitate is identified as a β-AlFeMnSi phase, with an aspect ratio of 5.72. Therefore, the phase is correctly classified as β-AlFeMnSi, confirming the accuracy of the classification.

[0036] Example 5:

[0037] The composition of precipitate 5 is 78.66% Al, 4.09% Fe, 7.20% Mn, and 6.58% Si, with an atomic ratio of (Fe+Mn) / Si of 1.72. Based on the composition analysis, the precipitate is identified as an α-AlFeMnSi phase, with an aspect ratio of 1.76. Therefore, the precipitate is correctly classified as an α-AlFeMnSi phase, confirming the accuracy of the classification.

[0038] Example 6:

[0039] The composition of precipitate 6 is 82.08% Al, 3.98% Fe, 4.74% Mn, and 7.37% Si, with an atomic ratio of (Fe+Mn) / Si of 1.13. Based on the composition analysis, the precipitate is identified as a β-AlFeMnSi phase, with an aspect ratio of 2.86. Therefore, the precipitate is correctly classified as a β-AlFeMnSi phase, confirming the accuracy of the classification.

[0040] Example 7:

[0041] The composition of precipitate 7 is 79.74% Al, 4.36% Fe, 5.75% Mn, and 7.46% Si, with an atomic ratio of (Fe+Mn) / Si of 1.35. Based on the composition analysis, the precipitate is identified as a β-AlFeMnSi phase, with an aspect ratio of 5.38. Therefore, the precipitate is correctly classified as a β-AlFeMnSi phase, confirming the accuracy of the classification.

[0042] Example 8:

[0043] The composition of precipitate 8 is 76.67% Al, 5.43% Fe, 7.21% Mn, and 8.90% Si, with an atomic ratio of (Fe+Mn) / Si of 1.42. Based on the composition analysis, the precipitate is identified as a β-AlFeMnSi phase, with an aspect ratio of 3.46. Therefore, the precipitate is correctly classified as a β-AlFeMnSi phase, confirming the accuracy of the classification.

[0044] Example 9:

[0045] The composition of precipitate 9 is 80.90% Al, 4.50% Fe, 4.14% Mn, and 8.26% Si, with an atomic ratio of (Fe+Mn) / Si of 1.05. Based on the composition analysis, the precipitate is identified as a β-AlFeMnSi phase, with an aspect ratio of 3.78. Therefore, the phase is correctly classified as β-AlFeMnSi.

[0046] Example 10:

[0047] The composition of precipitate 10 is 90.90% Al, 0.17% Fe, 0.03% Mn, and 7.68% Si, with an atomic ratio of (Fe+Mn) / Si of 0.29. Based on the composition analysis, it is a Si-rich phase with an aspect ratio of 2.17. According to the aspect ratio, it is classified as a β-AlFeMnSi phase, therefore the verification result is incorrect.

[0048] Example 11:

[0049] The composition of precipitate 11 is 82.01% Al, 5.15% Fe, 5.28% Mn, and 6.87% Si, with an atomic ratio of (Fe+Mn) / Si of 1.52. Based on the composition analysis, the precipitate is identified as an α-AlFeMnSi phase, with an aspect ratio of 2.45. The classification based on this aspect ratio confirms the correctness of the α-AlFeMnSi phase classification.

[0050] Example 12:

[0051] The composition of precipitate 12 is 89.53% Al, 2.09% Fe, 2.96% Mn, and 4.71% Si, with an atomic ratio of (Fe+Mn) / Si of 1.06. Based on the composition analysis, the precipitate is identified as a β-AlFeMnSi phase, with an aspect ratio of 8.46. Therefore, the precipitate is correctly classified as a β-AlFeMnSi phase, confirming the accuracy of the classification.

[0052] Example 13:

[0053] The composition of precipitate 13 is 80.78% Al, 4.77% Fe, 5.25% Mn, and 7.24% Si, with an atomic ratio of (Fe+Mn) / Si of 1.38. Based on the composition analysis, the precipitate is identified as a β-AlFeMnSi phase, with an aspect ratio of 5.19. Therefore, the phase is correctly classified as β-AlFeMnSi.

[0054] Example 14:

[0055] The composition of precipitate 14 is 84.57% Al, 4.19% Fe, 4.27% Mn, and 5.39% Si, with an atomic ratio of (Fe+Mn) / Si of 1.57. Based on the composition analysis, the precipitate is identified as an α-AlFeMnSi phase, with an aspect ratio of 1.29. Therefore, the precipitate is correctly classified as an α-AlFeMnSi phase, confirming the accuracy of the classification.

[0056] Example 15:

[0057] The composition of precipitate 15 is 80.56% Al, 5.69% Fe, 4.29% Mn, and 7.65% Si, with an atomic ratio of (Fe+Mn) / Si of 1.30. Based on the composition analysis, the precipitate is identified as a β-AlFeMnSi phase, with an aspect ratio of 2.91. The classification based on this aspect ratio confirms the correctness of the β-AlFeMnSi phase classification.

[0058] Example 16:

[0059] The composition of precipitate 16 is 80.35% Al, 4.63% Fe, 6.90% Mn, and 6.74% Si, with an atomic ratio of (Fe+Mn) / Si of 1.71. Based on the composition analysis, the precipitate is identified as an α-AlFeMnSi phase, with an aspect ratio of 1.47. Therefore, the precipitate is correctly classified as an α-AlFeMnSi phase, confirming the accuracy of the classification.

[0060] Example 17:

[0061] The composition of precipitate 17 is 91.16% Al, 1.90% Fe, 1.37% Mn, and 3.83% Si, with an atomic ratio of (Fe+Mn) / Si of 0.83. Based on the composition analysis, the precipitate is identified as a β-AlFeMnSi phase, with an aspect ratio of 2.88. Therefore, the phase is correctly classified as β-AlFeMnSi.

[0062] Example 18:

[0063] The composition of precipitate 18 is 92.18% Al, 5.97% Fe, 0.31% Mn, and 0.06% Si, with no (Fe+Mn) / Si atomic ratio. Based on the composition analysis, it is identified as an AlFe phase with an aspect ratio of 1.73. According to the aspect ratio, it is classified as an α-AlFeMnSi phase, but the verification result is incorrect.

[0064] Example 19:

[0065] The composition of precipitate 19 is 83.19% Al, 4.14% Fe, 4.67% Mn, and 6.20% Si, with an atomic ratio of (Fe+Mn) / Si of 1.42. Based on the composition analysis, the precipitate is identified as a β-AlFeMnSi phase, with an aspect ratio of 6.79. Therefore, the precipitate is correctly classified as a β-AlFeMnSi phase, confirming the accuracy of the classification.

[0066] Example 20:

[0067] The composition of precipitate 20 is 76.23% Al, 5.84% Fe, 7.90% Mn, and 8.13% Si, with an atomic ratio of (Fe+Mn) / Si of 1.69. Based on the composition analysis, the precipitate is identified as an α-AlFeMnSi phase, with an aspect ratio of 1.90. Therefore, the phase is correctly classified as α-AlFeMnSi.

[0068] Example 21:

[0069] The composition of precipitate 21 is 81.31% Al, 4.31% Fe, 5.95% Mn, and 6.72% Si, with an atomic ratio of (Fe+Mn) / Si of 1.53. Based on the composition analysis, it is identified as an α-AlFeMnSi phase with an aspect ratio of 4.99. However, based on this aspect ratio, it is classified as a β-AlFeMnSi phase, indicating an error in the verification result.

[0070] Example 22:

[0071] The composition of precipitate 22 is 77.71% Al, 4.09% Fe, 7.03% Mn, and 8.69% Si, with an atomic ratio of (Fe+Mn) / Si of 1.28. Based on the composition analysis, the precipitate is identified as a β-AlFeMnSi phase, with an aspect ratio of 4.73. Therefore, the precipitate is correctly classified as a β-AlFeMnSi phase, confirming the accuracy of the classification.

[0072] Example 23:

[0073] The composition of precipitate 23 is 79.06% Al, 4.74% Fe, 5.82% Mn, and 8.58% Si, with an atomic ratio of (Fe+Mn) / Si of 1.23. Based on the composition analysis, the precipitate is identified as a β-AlFeMnSi phase, with an aspect ratio of 4.73. Therefore, the phase is correctly classified as β-AlFeMnSi, confirming the accuracy of the classification.

[0074] Example 24:

[0075] The composition of precipitate 24 is 81.56% Al, 5.41% Fe, 3.70% Mn, and 7.20% Si, with an atomic ratio of (Fe+Mn) / Si of 1.27. Based on the composition analysis, it is identified as a β-AlFeMnSi phase, with an aspect ratio of 1.77. However, based on this aspect ratio, it is classified as an α-AlFeMnSi phase, indicating an error in the verification result.

[0076] Example 25:

[0077] The composition of precipitate 25 is 89.81% Al, 0.14% Fe, 0.06% Mn, and 9.09% Si, with an atomic ratio of (Fe+Mn) / Si of 0.02. Based on the composition analysis, it is identified as an AlSi phase with an aspect ratio of 5.40. According to the aspect ratio, it is classified as a β-AlFeMnSi phase, but the verification result is incorrect.

[0078] Table 1. Classification of EDS components and aspect ratio of precipitated phases.

[0079]

[0080]

[0081] In this study, 93 precipitates were randomly detected using EDS. The composition of the precipitates is shown in Table 1 (only 25 are listed). According to geometric factor analysis, 37 α-AlFeMnSi phases and 56 β-AlFeMnSi phases were detected. Based on compositional analysis, 39 α-AlFeMnSi phases, 47 β-AlFeMnSi phases, 5 AlSi phases, and 2 AlFe phases were detected. Comparative analysis of the composition and aspect ratio data of the 93 precipitates shows that the geometric factor method correctly distinguished α and β-AlFeMnSi phases in 82 cases and incorrectly in 11 cases, with an accuracy rate of 88.2%. Using the geometric factor method to distinguish α and β-AlFeMnSi phases from SEM images can lead to a decrease in accuracy by misclassifying small amounts of AlFe and AlSi phases in aluminum alloys as AlFeMnSi phases, as shown in precipitates 10, 18, and 25 in Table 1. Excluding the influence of other precipitated phases, and only analyzing the composition and aspect ratio data of 86 AlFeMnSi phases, the geometric factor method can achieve an accuracy of 95.3% in distinguishing between α-AlFeMnSi phases. Therefore, the geometric factor method can replace the traditional composition method to distinguish between α-AlFeMnSi phases in aluminum alloys, achieving the goals of improving detection efficiency and reducing testing costs, and providing effective assistance in evaluating alloy ingot quality and formulating homogenization processes.

[0082] This invention uses scanning electron microscopy (SEM) to observe the microstructure of as-cast and homogenized aluminum alloys. An image processing method is used to separate the alloy matrix and precipitates in the SEM images based on the color and grayscale differences between the aluminum alloy matrix and the precipitates. Then, the length, width, and area of ​​the precipitates are measured in batches, and the type of precipitate is distinguished based on its aspect ratio factor.

[0083] The above descriptions are merely embodiments of the present invention. Commonly known structures and characteristics are not described in detail here. Those skilled in the art are aware of all common technical knowledge in the field prior to the application date or priority date, are aware of all existing technologies in that field, and have the ability to apply conventional experimental methods prior to that date. Those skilled in the art can, under the guidance of this application, improve and implement this solution in combination with their own capabilities. Some typical known structures or methods should not be obstacles for those skilled in the art to implement this application. It should be noted that those skilled in the art can make several modifications and improvements without departing from the structure of the present invention. These should also be considered within the scope of protection of the present invention, and will not affect the effectiveness of the implementation of the present invention or the practicality of the patent. The scope of protection claimed in this application should be determined by the content of its claims, and the specific embodiments described in the specification can be used to interpret the claims.

Claims

1. A method for classifying α- and β-AlFeMnSi phases in as-cast precipitates of aluminum alloys, characterized in that: The method includes the following steps: (1) The microstructure of the aluminum alloy sample was observed using a scanning electron microscope (SEM). (2) Using image processing methods, the alloy matrix and precipitates in the SEM image are separated based on the color grayscale difference between the aluminum alloy matrix and the precipitates; Digital image processing methods were used to measure the maximum length Lmax, maximum width Wmax, and the sum of precipitation areas S of corresponding particle sizes for each precipitated phase in batches, and the Lmax / Wmax ratio of each precipitated phase was calculated. Then, a bar chart of precipitation area distribution for precipitated phases with different Lmax / Wmax ratios was plotted with the Lmax / Wmax ratio as the x-axis and the sum of precipitation areas S as the y-axis, and the peak precipitation area intervals of α and β-AlFeMnSi phases were identified from the chart. (3) The Lmax / Wmax ratio in the distribution histogram has two peak positions. The distribution of this peak is described by a normal distribution. The boundary position of the two peaks is the boundary point of the length and width ratio of α-AlFeMnSi and β-AlFeMnSi, and the critical length and width ratio k of the peak is determined. The particles to the left of the boundary point represent the particles with an Lmax / Wmax ratio of 1.0-k, which is the peak interval of α-AlFeMnSi phase precipitation. The particles with an Lmax / Wmax ratio greater than k to the right of the boundary point represent the peak interval of β-AlFeMnSi phase precipitation.

2. The method for classifying as-cast precipitates α and β-AlFeMnSi phases in aluminum alloys according to claim 1, characterized in that: The SEM image capture magnification in step (1) is 200-500x.

3. The method for classifying as-cast precipitates α and β-AlFeMnSi phases in aluminum alloys according to claim 1, characterized in that: Step (2) involves separating the alloy matrix and precipitates in the SEM image. This means extracting the grayscale values ​​of the SEM image, drawing a grayscale histogram, finding the grayscale thresholds of the aluminum alloy matrix and the second phase, and separating the aluminum alloy matrix and the second phase based on these thresholds.

4. The method for classifying as-cast precipitates α and β-AlFeMnSi phases in aluminum alloys according to claim 3, characterized in that: In step (2), the aluminum alloy matrix in the SEM image appears grayish-black, and the second phase appears grayish-white.

5. The method for classifying α- and β-AlFeMnSi phases in as-cast precipitates in aluminum alloys according to claim 1, characterized in that: The number of statistical samples of precipitated phase particles in step (2) is greater than 1000.

6. The method for classifying as-cast precipitates α and β-AlFeMnSi phases in aluminum alloys according to claim 1, characterized in that: Before step (3), after gradually screening out the small spot precipitation that meets the sample requirements and removes the influence of the relative experimental results on the experimental results, observe the two peak positions of the Lmax / Wmax ratio in the distribution histogram.

7. The method for classifying as-cast precipitates α and β-AlFeMnSi phases in aluminum alloys according to claim 6, characterized in that: The fine dot-like precipitates have a precipitation area of ​​less than 1.0 μm. 2 Fine granular precipitates.

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