Quantitative statistical method of precipitated phase in nickel-based superalloy

Abstract

The application discloses a quantitative statistical method of precipitated phases in a nickel-based high-temperature alloy, and belongs to the field of material microstructure research and analysis. The quantitative statistical method of the nickel-based alloy precipitated phases provided by the application uses a thermodynamic analysis software to obtain a non-equilibrium solidification phase diagram of the alloy, determines the precipitated temperature interval and the precipitated sequence of each precipitated phase in the alloy, uses a DSC differential thermal analyzer to test a heat flow curve of the alloy, uses Origin to divide a precipitated phase spectrum peak of the heat flow curve, and integrates the spectrum peak to obtain a spectrum peak area, namely, the melting enthalpy of each precipitated phase, which represents the content of the precipitated phase in the alloy under different process conditions; comparison of the spectrum peak areas of the precipitated phases obtains the mass change of each main precipitated phase in the alloy before and after the process. The analysis process of the application is convenient and fast, the result is accurate, excellent effects are achieved in processing some complex eutectic phases, and the application has a very wide application prospect in nickel-based alloys and other metal materials.

Description

Technical Field

[0001] This invention belongs to the field of material microstructure research and analysis, specifically relating to a quantitative statistical method for precipitated phases in nickel-based superalloys. Background Technology

[0002] Nickel-based superalloys are widely used in high-temperature reaction devices such as aero-engine components, chemical reactors, pipelines transporting gaseous and liquid media, nuclear reactor pressure vessels, and high-temperature furnaces due to their excellent high-temperature strength, oxidation resistance, and corrosion resistance. In nickel-based superalloys, the type, quantity, and variety of precipitates are key indicators affecting alloy performance. For example, in age-hardening precipitation-strengthened nickel-based alloys, the strengthening phase γ′ (Ni3(Al, Ti)) is dominant, hindering dislocation movement to enhance the alloy's high-temperature strength and creep resistance. The size, distribution, and volume fraction of γ′ precipitates are crucial factors determining the precipitation-strengthening effect. In addition, carbides (MC, M) are another major precipitate affecting alloy performance. 23 C6, M6C). MC carbides typically form during solidification, are very stable at high temperatures, and have a significant impact on the mechanical properties of the alloy. M 23 C6 carbides mainly form along grain boundaries, enhancing grain boundary strength and improving resistance to intergranular cracking. M6C carbides typically form in nickel-based alloys when elements such as W and Mo are present, contributing to improved alloy hardness and high-temperature stability. Topologically close-packed phases (TCP phases), including σ, μ, and Laves phases, are generally considered detrimental to the mechanical properties of alloys. TCP phases form during prolonged high-temperature exposure, consuming strengthening elements in the matrix and thus reducing the alloy's strength and ductility. Therefore, in the research of nickel-based superalloys, the quantitative statistical analysis of precipitates in the alloy is a crucial method for reflecting the quality of processing techniques. Current research in this area generally lacks effective quantitative statistical methods for precipitates. Patent CN113777115A discloses a quantitative statistical method for precipitates in alloys. The general principle is to first determine the types of precipitates using TEM analysis results, then perform statistical analysis on a large number of relevant precipitate images using relevant image acquisition equipment, and finally obtain the quantitative statistical results of precipitates in the alloy. This method is complex, time-consuming, and labor-intensive. Furthermore, the analysis of a large number of images in the second stage relies on the experimenter's subjective judgment, resulting in inaccurate statistical results.

[0003] Currently, the main method for quantitative analysis of precipitates in nickel-based alloys is still the cross-sectional method using numerous images. This method has several significant drawbacks. First, multiple straight lines are randomly drawn on the microscopic image; these lines are called cross-sections. These cross-sections should cover the entire observation area as evenly as possible. The direction of the cross-sections can be random or regular, such as perpendicular or parallel to a specific direction. Then, the number of intersections between each cross-section and the precipitate or specific microstructure is recorded, and the recording of each intersection should be as accurate as possible. Based on the number of intersections and the total length of the cross-sections, information such as the volume fraction of the precipitate, the phase interface density, and the size distribution is calculated. Commonly used formulas include:

[0004] Volume fraction:

[0005]

[0006] Where P represents the total number of intersection points between the truncation and the precipitated phase, and L represents the total length of the truncation.

[0007] Phase interface density:

[0008]

[0009] Where P still represents the total number of intersection points between the truncation and the precipitated phase, and L represents the total length of the truncation.

[0010] As can be seen from the above, the calculation process of the intercept method is relatively complex, and its accuracy is limited by the number and arrangement of intercepts. A large number of samples are required to ensure accuracy, and a small number of intercepts or randomly distributed intercepts may lead to inaccurate results. Moreover, if the selection of intercepts is biased towards certain specific regions, statistical bias may occur. In addition, this method assumes that the intersection points of the intercepts and the precipitates are uniformly distributed. However, for precipitates with complex shapes or large size variations, this assumption may not hold, thus affecting the accuracy of the results. This is most critical in the statistical analysis of precipitates in nickel-based alloys, because most of the precipitates to be statistically analyzed do not have a regular shape. In particular, it is difficult to make accurate judgments when dealing with some eutectic precipitates with complex distribution patterns. For example, taking GH3625 alloy as an example, when w[C] = 0.02%, the NbC and Laves phases in the alloy mainly exist in the form of eutectic phases. Ordinary statistical methods cannot separate the two, making it difficult to obtain quantitative statistical results for each of the two precipitates. Secondly, the effectiveness of the truncation method depends on the contrast between the precipitated phase and the matrix under the microscope. If the contrast is not obvious, the identification of the intersection of the truncation and the precipitated phase may produce errors.

[0011] Differential scanning calorimetry (DSC) is an analytical method that measures the relationship between the power difference between the sample and the reference material and temperature while keeping the sample and reference temperatures constant under programmed temperature conditions. It has wide applications in the study of the physical properties of metallic materials. Currently, the heating rate range of experimental thermal analyzers can be from 0.1℃ / min to 500℃ / min, with a commonly used range of 5℃ / min to 20℃ / min, especially 10℃ / min. Increasing the heating rate β increases the peak temperature T. p A linear increase in β, along with a slight increase in peak area, leads to a steeper peak shape and masks small phase transition peaks, thus affecting the accuracy of thermal analysis. From the perspective of improving the accuracy of thermal analysis, a low heating rate is advantageous for general samples. However, for phase transition processes with minimal thermal effects, or when the sample size is very small, a higher heating rate often improves the sensitivity of the results. Therefore, depending on the specific circumstances of the sample being measured, different heating rates are sometimes used in the study.

[0012] Therefore, to obtain better and more accurate quantitative statistical results of precipitates in nickel-based alloys, a new statistical method for precipitate analysis needs to be developed. Moreover, this method should be as simple as possible, effectively separating complex eutectic phases and obtaining quantitative statistical results for each precipitate separately. Summary of the Invention

[0013] In view of the technical problems mentioned in the background, this invention provides a quantitative statistical method for the analysis of precipitates in nickel-based alloys that is convenient, quick, and accurate. By comparing this method with other existing techniques in the same field, this method is used for the quantitative statistical analysis of precipitates in alloys.

[0014] This invention is achieved using the following technical means:

[0015] A quantitative statistical method for precipitated phases in nickel-based superalloys includes the following steps:

[0016] (1) Input the specific composition of the alloy into the thermodynamic analysis software to obtain the non-equilibrium solidification phase diagram of the alloy, and determine the precipitation temperature range and precipitation order of each precipitated phase in the alloy; the thermodynamic analysis software is one of Thermo-Calc, JMatPro, FactSage, and Panda.

[0017] (2) Determine the sampling location of the alloy sample to be tested according to the actual process conditions, and pre-treat the alloy to be tested;

[0018] (3) Turn on the computer and DSC host, and start the test after the power-on and warm-up period. Confirm the protective gas and purging gas used for the measurement. The protective gas and purging gas are either argon or nitrogen.

[0019] (4) Weigh the empty crucible on a balance and tare it. Then put the sample into the empty crucible and weigh the sample mass, accurate to 0.01 mg. Add a crucible lid with a small hole. When the crucible is an Al2O3 crucible, press the crucible and the crucible lid together with a press. Place the sample crucible in the sample position of the instrument, and place a crucible of the same material and specifications in the reference position as a reference.

[0020] (5) Open the measurement software and set the DSC measurement parameters, including sample name, number, mass, type of gas used and flow rate;

[0021] (6) Set the temperature program, add each temperature segment in the DSC temperature program one by one, and set the corresponding condition parameters for each temperature segment.

[0022] (7) Set the measurement file name, initialize the working conditions and start the measurement to obtain the heat flow curve of a nickel-based alloy under different process conditions at the set melting rate;

[0023] (8) Use data analysis software to analyze the obtained heat flow curves: First, combine the precipitation temperature range and precipitation sequence of each precipitated phase in the alloy non-equilibrium solidification phase diagram, and calibrate the precipitated phase represented by each peak on the heat flow curve; then, segment the precipitation temperature range of each precipitated phase so that the spectral peaks of each precipitated phase are separated in the heat flow curve.

[0024] (9) Draw a baseline starting from the tangent position of the initial melting temperature of the first precipitate and include all the precipitate peaks on the heat flow curve; use data analysis software to perform integral calculations on each precipitate peak to obtain the area of ​​each peak, i.e., the melting enthalpy of each precipitate, which represents the content of precipitates in the alloy under different process conditions; compare the areas of each precipitate peak to obtain the mass change of each major precipitate in the alloy before and after the process;

[0025] In step (1) of the present invention, the precipitation order of the precipitated phase given by the non-equilibrium solidification phase diagram is determined, but the precipitation temperature range is slightly different from the DSC heat flow curve. The precipitation temperature range is determined according to the relationship between the peak of the precipitated phase spectrum and the baseline of the heat flow curve.

[0026] In step (2) of this invention, the alloy sampling location is determined by the experimental design. The content of precipitated phases at different locations of the ingot is different, and the analytical results obtained are also different. According to the alloy density and equipment requirements, the mass range of the experimental sample is 50mg to 110mg, and the error does not exceed 1mg. According to the size difference of the crucible of different differential thermal analyzers, the diameter of the sample should be such that it can be completely placed in the crucible, and the height should be as small as possible to reduce the systematic error caused by the difference in thermal conduction between the sample and the bottom of the crucible. In addition, the oxide layer on the sample surface should be completely polished clean.

[0027] In step (3) of this invention, the purity of argon and nitrogen is ≥99.999%, which is mainly to prevent the sample from oxidizing at high temperatures.

[0028] In step (6) of the present invention, the condition parameters corresponding to different temperature ranges are as follows: from room temperature to 800℃, the melting rate is set to ≤50℃ / min; from 800℃ to 1400℃, the melting rate is set to 5~20℃ / min; after 1400℃, no specific cooling rate is set, and the furnace is cooled.

[0029] In steps (8) and (9), the data analysis software includes Origin, MATLAB, and Python.

[0030] The heating rate range of commercial differential thermal analyzers is 0.1℃ / min to 500℃ / min, with a commonly used range of 5℃ / min to 20℃ / min, and previously 10℃ / min being the most common. Increasing the heating rate linearly increases the peak temperature, which in turn increases the peak area to some extent, making the peak shape steeper and masking small precipitation phase transitions, thus affecting the peak resolution. From the perspective of improving resolution, using a low heating rate (≤20℃ / min) is advantageous. However, for transitions with large thermal effects, or in the case of alloy samples, a lower heating rate often reduces the sensitivity of the results. Therefore, depending on the actual situation of the sample being measured, different heating rates are often used for research.

[0031] Compared with the prior art, the advantages of the present invention are: the analysis process is convenient and fast, the results are accurate, and it also achieves excellent results in dealing with some complex eutectic phases. It has a very broad application prospect in nickel-based alloys and other metallic materials. Attached Figure Description

[0032] Figure 1 This is a non-equilibrium solidification phase diagram of the alloy composition used in the embodiments of the present invention.

[0033] Figure 2 These are the DSC heat flow curves and quantitative statistical results of precipitated phases of the nickel-based alloy obtained in Example 1.

[0034] Figure 3These are the DSC heat flow curves and quantitative statistical results of precipitated phases of the nickel-based alloy obtained in Example 2.

[0035] Figure 4 These are the DSC heat flow curves and quantitative statistical results of precipitated phases of the nickel-based alloy obtained in Example 3.

[0036] Figure 5 These are the DSC heat flow curves and quantitative statistical results of precipitated phases of the nickel-based alloy obtained in Example 4.

[0037] Figure 6 The results are the DSC heat flow curves and quantitative statistical results of precipitated phases of the nickel-based alloy obtained in Comparative Example 1.

[0038] Figure 7 The results are the DSC heat flow curves and quantitative statistical results of precipitated phases of the nickel-based alloy obtained in Comparative Example 2. Detailed Implementation

[0039] The operation process and application effects of the method of the present invention in specific experimental analysis will be described in more detail below with reference to the accompanying drawings.

[0040] The non-equilibrium solidification phase diagram of the alloy used in the embodiments of the present invention is as follows: Figure 1 As shown.

[0041] Example 1:

[0042] (1) First, the non-equilibrium solidification phase diagram of the experimental alloy was calculated using the Scheil solidification module in Thermo-Calc 2019a thermodynamic analysis software, such as... Figure 1 As shown in the phase diagram, the precipitation temperature and precipitation sequence of each precipitated phase in the alloy are determined to be L→L+γ (1237℃)→L+γ+MC (1146℃)→L+γ+MC+δ (1145℃)→L+γ+MC+δ+σ.

[0043] (2) Determine the sampling location of the alloy sample to be tested according to the actual process conditions. The sample size is φ3×1mm, and the surface oxide layer is removed.

[0044] (3) Turn on the computer and DSC host. The DSC device model is DSC404F3. After the computer has been warmed up for half an hour, the test will begin. Confirm the purge gas used for the measurement. Argon is used as both the protective gas and the purge gas.

[0045] (4) Weigh the empty crucible on a balance and tare it. Then put the sample into the empty crucible and weigh it. The sample mass is 60.135 mg, accurate to 0.01 mg. Put the crucible lid on.

[0046] (5) Open the measurement software and set the DSC measurement parameters, mainly the sample name, number, mass, type of gas used and flow rate settings.

[0047] (6) Add each temperature segment in the DSC temperature program one by one, and set the corresponding experimental conditions for each temperature segment. When the temperature rises from room temperature to 800℃, the heating rate is 50℃ / min. When the temperature rises from 800℃ to 1400℃, the heating rate is 10℃ / min. After 1400℃, no specific cooling rate is set, and the temperature is cooled with the furnace.

[0048] (7) Set the measurement file name, initialize the working conditions, and start the measurement. Finally, the heat flow curve of a nickel-based alloy under the set experimental conditions is obtained, such as... Figure 2 As shown, the precipitated phases are clearly separated and the spectral peaks are smooth, indicating that the DSC heat flow curve has good sensitivity under the sample quality and program settings.

[0049] (8) Analyze the obtained heat flow curves using Origin 2024. First, based on the precipitation temperature and precipitation sequence of each precipitated phase in the alloy non-equilibrium solidification phase diagram in step (1), calibrate the precipitated phase represented by each peak on the heat flow curve. Then, segment the spectral peaks of each precipitated phase in the Origin data workbook to separate the spectral peaks of each precipitated phase in the heat flow curve.

[0050] (9) Starting from the tangent position of the initial melting temperature of the first precipitated phase, draw a baseline that includes all precipitated phase peaks on the heat flow curve. Use the built-in integration tool of Origin 2024 to integrate each precipitated phase peak to obtain the area of ​​each peak, which is the enthalpy of melting of each precipitated phase, representing the content of precipitated phases in the alloy under different process conditions. By comparing the areas of each precipitated phase peak, the mass change of each major precipitated phase in the alloy before and after the process can be determined.

[0051] Example 2:

[0052] (1) First, the non-equilibrium solidification phase diagram of the experimental alloy was calculated using the Scheil solidification module in Thermo-Calc 2019a thermodynamic analysis software, such as... Figure 1 As shown in the phase diagram, the precipitation temperature and precipitation sequence of each precipitated phase in the alloy are determined to be L→L+γ (1237℃)→L+γ+MC (1146℃)→L+γ+MC+δ (1145℃)→L+γ+MC+δ+σ.

[0053] (2) Determine the sampling location of the alloy sample to be tested according to the actual process conditions. The sample size is φ3×2mm, and the surface oxide layer is removed.

[0054] (3) Turn on the computer and DSC host. The DSC device model is DSC404F3. After the computer has been warmed up for half an hour, the test will begin. Confirm the purge gas used for the measurement. Argon is used as both the protective gas and the purge gas.

[0055] (4) Weigh the empty crucible on a balance and tare it. Then put the sample into the empty crucible and weigh it. The sample mass is 119.60 mg, accurate to 0.01 mg. Put the crucible lid on.

[0056] (5) Open the measurement software and set the DSC measurement parameters, mainly the sample name, number, mass, type of gas used and flow rate settings.

[0057] (6) Add each temperature segment in the DSC temperature program one by one, and set the corresponding experimental conditions for each temperature segment. The specific experimental program is set as follows: when the temperature rises from room temperature to 800℃, the heating rate is 50℃ / min; when the temperature rises from 800℃ to 1400℃, the heating rate is 10℃ / min; after 1400℃, no specific cooling rate is set, and the temperature is cooled with the furnace.

[0058] (7) Set the measurement file name, initialize the working conditions, and start the measurement. Finally, obtain the heat flow curve of a nickel-based alloy under the set experimental conditions, such as... Figure 3 As shown.

[0059] (8) Analyze the obtained heat flow curves using Origin 2024. First, based on the precipitation temperature and precipitation sequence of each precipitated phase in the alloy non-equilibrium solidification phase diagram in step (1), calibrate the precipitated phase represented by each peak on the heat flow curve. Then, segment the spectral peaks of each precipitated phase in the Origin data workbook to separate the spectral peaks of each precipitated phase in the heat flow curve.

[0060] (9) Starting from the tangent position of the initial melting temperature of the first precipitated phase, draw a baseline that includes all precipitated phase peaks on the heat flow curve. Use the built-in integration tool of Origin 2024 to integrate each precipitated phase peak to obtain the area of ​​each peak, which is the enthalpy of melting of each precipitated phase, representing the content of precipitated phases in the alloy under different process conditions. By comparing the areas of each precipitated phase peak, the mass change of each major precipitated phase in the alloy before and after the process can be determined.

[0061] Example 3:

[0062] (1) First, the non-equilibrium solidification phase diagram of the experimental alloy was calculated using the Scheil solidification module in Thermo-Calc 2019a thermodynamic analysis software, such as... Figure 1As shown in the phase diagram, the precipitation temperature and precipitation sequence of each precipitated phase in the alloy are determined to be L→L+γ (1237℃)→L+γ+MC (1146℃)→L+γ+MC+δ (1145℃)→L+γ+MC+δ+σ.

[0063] (2) Samples were taken from the center of the blank group and the alloy ingot after the application process, and marked as S1 and S2 respectively. The sample size was φ3×1mm, and the surface oxide layer was removed.

[0064] (3) Turn on the computer and DSC host. The DSC device model is DSC404F3. After the computer has been warmed up for half an hour, the test will begin. Confirm the purge gas used for the measurement. Argon is used as both the protective gas and the purge gas.

[0065] (4) Weigh the empty crucible on a balance and tare it. Then put the sample into the empty crucible and weigh it. The sample mass is 60 mg, and the mass value is accurate to 0.01 mg. Put the crucible lid on.

[0066] (5) Open the measurement software and set the DSC measurement parameters, mainly the sample name, number, mass, type of gas used and flow rate settings.

[0067] (6) Add each temperature segment in the DSC temperature program one by one, and set the corresponding experimental conditions for each temperature segment. The specific experimental program is set as follows: when the temperature rises from room temperature to 800℃, the heating rate is 50℃ / min; when the temperature rises from 800℃ to 1400℃, the heating rate is 5℃ / min; after 1400℃, no specific cooling rate is set, and the temperature is cooled with the furnace.

[0068] (7) Set the measurement file name, initialize the working conditions, and start the measurement. Finally, the heat flow curves and quantitative statistical results of precipitates of a nickel-based alloy before and after the application process were obtained, such as... Figure 4 As shown in (a, b).

[0069] (8) Analyze the obtained heat flow curves using Origin 2024. First, based on the precipitation temperature and precipitation sequence of each precipitated phase in the alloy non-equilibrium solidification phase diagram in step (1), calibrate the precipitated phase represented by each peak on the heat flow curve. Then, segment the spectral peaks of each precipitated phase in the Origin data workbook to separate the spectral peaks of each precipitated phase in the heat flow curve.

[0070] (9) Starting from the tangent position of the initial melting temperature of the first precipitated phase, draw a baseline that includes all precipitated phase peaks on the heat flow curve. Use the built-in integration tool in Origin 2024 to integrate each precipitated phase peak to obtain the area of ​​each peak, which is the enthalpy of melting of each precipitated phase, representing the content of precipitated phases in the alloy. By comparing the areas of each precipitated phase peak, the mass change of each major precipitated phase in the alloy before and after the application process can be determined.

[0071] Example 4:

[0072] (1) First, the non-equilibrium solidification phase diagram of the experimental alloy was calculated using the Scheil solidification module in Thermo-Calc 2019a thermodynamic analysis software, such as... Figure 1 As shown in the phase diagram, the precipitation temperature and precipitation sequence of each precipitated phase in the alloy are determined to be L→L+γ (1237℃)→L+γ+MC (1146℃)→L+γ+MC+δ (1145℃)→L+γ+MC+δ+σ.

[0073] (2) Samples were taken from the center of the blank group and the alloy ingot after the application process. The sample size was φ3×1mm, and the surface oxide layer was removed.

[0074] (3) Turn on the computer and DSC host. The DSC device model is DSC404F3. After the computer has been warmed up for half an hour, the test will begin. Confirm the purge gas used for the measurement. Argon is used as both the protective gas and the purge gas.

[0075] (4) Weigh the empty crucible on a balance and tare it. Then put the sample into the empty crucible and weigh it. The sample mass is 60 mg, and the mass value is accurate to 0.01 mg. Put the crucible lid on.

[0076] (5) Open the measurement software and set the DSC measurement parameters, mainly the sample name, number, mass, type of gas used and flow rate settings.

[0077] (6) Add each temperature segment in the DSC temperature program one by one, and set the corresponding experimental conditions for each temperature segment. The specific experimental program is set as follows: when the temperature rises from room temperature to 800℃, the heating rate is 50℃ / min; when the temperature rises from 800℃ to 1400℃, the heating rate is 10℃ / min; after 1400℃, no specific cooling rate is set, and the temperature is cooled with the furnace.

[0078] (7) Set the measurement file name, initialize the working conditions, and start the measurement. Finally, the heat flow curves of a nickel-based alloy before and after the application process were obtained, as shown below. Figure 5 As shown in (a, b); the quantitative statistical results of the precipitated phase are as follows: Figure 5 As shown in (c, d).

[0079] (8) Analyze the obtained heat flow curves using Origin 2024. First, based on the precipitation temperature and precipitation sequence of each precipitated phase in the alloy non-equilibrium solidification phase diagram in step (1), calibrate the precipitated phase represented by each peak on the heat flow curve. Then, segment the spectral peaks of each precipitated phase in the Origin data workbook to separate the spectral peaks of each precipitated phase in the heat flow curve.

[0080] (9) Starting from the tangent position of the initial melting temperature of the first precipitated phase, draw a baseline that includes all precipitated phase peaks on the heat flow curve. Use the built-in integration tool in Origin 2024 to integrate each precipitated phase peak to obtain the area of ​​each peak, which is the enthalpy of melting of each precipitated phase, representing the content of precipitated phases in the alloy under different process conditions. By comparing the areas of each precipitated phase peak, the mass change of each major precipitated phase in the alloy before and after the application process can be determined.

[0081] Comparative Example 1:

[0082] (1) First, the non-equilibrium solidification phase diagram of the experimental alloy was calculated using the Scheil solidification module in Thermo-Calc 2019a thermodynamic analysis software, such as... Figure 1 As shown in the phase diagram, the precipitation temperature and precipitation sequence of each precipitated phase in the alloy are determined to be L→L+γ (1237℃)→L+γ+MC (1146℃)→L+γ+MC+δ (1145℃)→L+γ+MC+δ+σ.

[0083] (2) Determine the sampling location of the alloy sample to be tested according to the actual process conditions. The sample size is φ2×0.5mm, and the surface oxide layer is removed.

[0084] (3) Turn on the computer and DSC host. The DSC device model is DSC404F3. After the computer has been warmed up for half an hour, the test will begin. Confirm the purge gas used for the measurement. Argon is used as both the protective gas and the purge gas.

[0085] (4) Weigh the empty crucible on a balance and tare it. Then put the sample into the empty crucible and weigh it. The sample mass is 14.910 mg, accurate to 0.01 mg. Put the crucible lid on.

[0086] (5) Open the measurement software and set the DSC measurement parameters, mainly the sample name, number, mass, type of gas used and flow rate settings.

[0087] (6) Add each temperature segment in the DSC temperature program one by one, and set the corresponding experimental conditions for each temperature segment. The specific experimental program is set as follows: when the temperature rises from room temperature to 800℃, the heating rate is 50℃ / min; when the temperature rises from 800℃ to 1400℃, the heating rate is 20℃ / min; after 1400℃, no specific cooling rate is set, and the temperature is cooled with the furnace.

[0088] (7) Set the measurement file name, initialize the working conditions, and start the measurement. Finally, obtain the heat flow curve of a nickel-based alloy under the set experimental conditions, such as... Figure 6 As shown in the figure, under these experimental conditions, the alloy's DSC curve has many impurity peaks, and the sensitivity of the DSC heat flow curve is poor, making it unsuitable for statistical use.

[0089] Comparative Example 2:

[0090] (1) First, the non-equilibrium solidification phase diagram of the experimental alloy was calculated using the Scheil solidification module in Thermo-Calc 2019a thermodynamic analysis software, such as... Figure 1 As shown in the phase diagram, the precipitation temperature and precipitation sequence of each precipitated phase in the alloy are determined to be L→L+γ (1237℃)→L+γ+MC (1146℃)→L+γ+MC+δ (1145℃)→L+γ+MC+δ+σ.

[0091] (2) Determine the sampling location of the alloy sample to be tested according to the actual process conditions. The sample size is φ3×5mm, and the oxide layer is removed.

[0092] (3) Turn on the computer and DSC host. The DSC device model is DSC404F3. After the computer has been warmed up for half an hour, the test will begin. Confirm the purge gas used for the measurement. Argon is used as both the protective gas and the purge gas.

[0093] (4) Weigh the empty crucible on a balance and tare it. Then put the sample into the empty crucible and weigh it. The sample mass is 307 mg, accurate to 0.01 mg. Put the crucible lid on.

[0094] (5) Open the measurement software and set the DSC measurement parameters, mainly the sample name, number, mass, type of gas used and flow rate settings.

[0095] (6) Add each temperature segment in the DSC temperature program one by one, and set the corresponding experimental conditions for each temperature segment. The specific experimental program is set as follows: when the temperature rises from room temperature to 800℃, the heating rate is 50℃ / min; when the temperature rises from 800℃ to 1400℃, the heating rate is 20℃ / min; after 1400℃, no specific cooling rate is set, and the temperature is cooled with the furnace.

[0096] (7) Set the measurement file name, initialize the working conditions, and start the measurement. Finally, obtain the heat flow curve of a nickel-based alloy under the set experimental conditions, such as... Figure 7 As shown in the figure, the sensitivity of the heat flow curve becomes very poor at this sample mass, rendering it essentially unusable.

Claims

1. A quantitative statistical method for precipitated phases in nickel-based superalloys, characterized in that, Includes the following steps: (1) Input the specific composition of the alloy into the thermodynamic analysis software to obtain the non-equilibrium solidification phase diagram of the alloy and determine the precipitation temperature range and precipitation sequence of each precipitated phase in the alloy. (2) Determine the sampling location of the alloy sample to be tested according to the actual process conditions, and pre-process the alloy sample to be tested; (3) Turn on the computer and DSC host, and start the test after the power is turned on and warmed up. Confirm the protective gas and purge gas used for the measurement. (4) Weigh the empty crucible on a balance and tare it. Then put the sample into the empty crucible and weigh the sample mass, accurate to 0.01 mg. Add a crucible lid with a small hole and place the sample crucible in the sample position of the instrument. At the same time, place a crucible of the same material and specifications in the reference position as a reference. (5) Open the measurement software and set the DSC measurement parameters, including sample name, number, mass, type of gas used and flow rate; (6) Set the temperature program, add each temperature segment in the DSC temperature program one by one, and set the corresponding condition parameters for each temperature segment. (7) Set the measurement file name, initialize the working conditions and start the measurement to obtain the heat flow curve of a nickel-based alloy under different process conditions at the set melting rate; (8) Use data analysis software to analyze the obtained heat flow curves: First, combine the precipitation temperature range and precipitation sequence of each precipitated phase in the alloy non-equilibrium solidification phase diagram, and calibrate the precipitated phase represented by each peak on the heat flow curve; then, segment the precipitation temperature range of each precipitated phase so that the spectral peaks of each precipitated phase are separated in the heat flow curve. (9) Draw a baseline starting from the tangent position of the initial melting temperature of the first precipitate and include all the precipitate peaks on the heat flow curve; use data analysis software to perform integral calculations on each precipitate peak to obtain the area of ​​each peak, i.e. the melting enthalpy of each precipitate, which represents the content of precipitates in the alloy under different process conditions; compare the areas of each precipitate peak to obtain the mass change of each precipitate in the alloy before and after the process.

2. The quantitative statistical method for precipitated phases in nickel-based superalloys according to claim 1, characterized in that, In step (1), the thermodynamic analysis software is one of Thermo-Calc, JMatPro, FactSage, or Panda.

3. The quantitative statistical method for precipitated phases in nickel-based superalloys according to claim 1, characterized in that, In step (2), the mass range of the alloy sample to be tested is 50mg to 110mg, with an error not exceeding 1mg; depending on the size difference of the crucible of different differential thermal analyzers, the diameter of the sample should be such that it can be completely placed in the crucible; the oxide layer on the surface of the sample needs to be polished clean.

4. The quantitative statistical method for precipitated phases in nickel-based superalloys according to claim 1, characterized in that, In step (3), the protective gas and the purging gas are either argon or nitrogen, and the purity of argon and nitrogen is ≥99.999%.

5. The quantitative statistical method for precipitated phases in nickel-based superalloys according to claim 1, characterized in that, In step (4), when the crucible is an Al2O3 crucible, the crucible and the crucible lid are pressed together using a press.

6. The quantitative statistical method for precipitated phases in nickel-based superalloys according to claim 1, characterized in that, In step (6), the condition parameters corresponding to different temperature ranges are as follows: from room temperature to 800℃, the melting rate is set to ≤50℃ / min; from 800℃ to 1400℃, the melting rate is set to 5℃ / min to 20℃ / min; after 1400℃, no specific cooling rate is set, and the furnace is cooled.

7. The quantitative statistical method for precipitated phases in nickel-based superalloys according to claim 1, characterized in that, In steps (8) and (9), the data analysis software includes Origin, MATLAB, and Python.

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