Method for determining and correcting interference elements of magnesium in nickel-based alloy measured by direct-reading spectrometer

Abstract

The invention discloses a method for determining and correcting interference elements of magnesium in nickel-based alloy by using a direct-reading spectrometer. The method comprises the following steps: (1) selecting alloy elements with the content of more than 0.1% in the nickel-based alloy as potential interference elements; (2) determining the Mg content by using a standard sample group containing gradient Mg content and adopting a direct-reading spectrometer to obtain a standard value of each standard sample; (3) adding correction items of the potential interference elements into the standard sample group one by one, and determining the Mg content by adopting a direct-reading spectrometer to obtain a correction determination value after each potential interference element is added into each standard sample; and (4) after a certain potential interference element is added for correction, if the reduction amplitude of the relative deviation between the corrected measured values of at least three standard samples and the standard values is greater than 15%, meanwhile, the relative standard deviation of all the corrected measured values is less than 8%, and the correlation coefficient R2 of the corrected measured value working curve is greater than 0.98, determining that the potential interference element is an interference element. The method realizes rapid and accurate determination.

Description

Technical Field

[0001] The invention belongs to the technical field of material composition analysis and determination, in particular to a method for determining and correcting interfering elements in magnesium in a nickel-based alloy using a direct-reading spectrometer. Background Art

[0002] Nickel-based alloys, due to their excellent properties, are widely used in numerous military and civilian fields, including aerospace, nuclear energy, power generation, and transportation. With the continuous development of modern industry, the requirements for material properties are becoming increasingly stringent, prompting a high level of attention to the research and development of various new materials. In nickel-based alloys, an appropriate amount of magnesium can significantly improve the morphology of grain boundary carbides, transforming them from strips to fine blocks, thereby effectively improving the alloy's impact resistance.

[0003] Currently, the detection of trace magnesium in alloys is mostly done using inductively coupled plasma atomic emission spectrometry (ICP-OES). However, this method has many limitations. Because nickel-based alloys are difficult to completely dissolve, wet chemical analysis is slow and inefficient, and the operation process is complex, making it unable to meet the needs of modern production for rapid and efficient testing.

[0004] While optical emission spectrometers (OES) offer advantages such as simultaneous multi-element determination, high precision, minimal matrix effects, and low detection limits, in practice, the factory-configured magnesium calibration curve is found to be inappropriate for testing actual production samples, and the conventional "control sample method" also struggles to obtain accurate measurement results. Therefore, developing a method for determining and correcting interference with magnesium in nickel-based alloys using spark emission spectrometers is of great practical significance. Summary of the Invention

[0005] The technical problem to be solved by the present invention is to provide a method for determining interfering elements in the determination of magnesium in nickel-based alloys by a direct-reading spectrometer; the present invention also provides a method for correcting interfering elements in the determination of magnesium in nickel-based alloys by a direct-reading spectrometer to obtain accurate measurement results.

[0006] In order to solve the above technical problems, the technical solution adopted by the determination method of the present invention includes the following steps: (1) selecting an alloying element with a content greater than 0.1% in the nickel-based alloy as a potential interfering element;

[0007] (2) Using a standard sample set containing a gradient of Mg content, the Mg content was determined using a direct reading spectrometer to obtain the standard value of each standard sample;

[0008] (3) Add correction items of potential interfering elements one by one to the standard sample group, and use direct reading spectrometer to determine the Mg content, and obtain the corrected measurement value of each standard sample after adding each potential interfering element;

[0009] (4) After adding a potential interfering element for correction, if the relative deviation between the corrected values and the standard values of at least three standard samples is reduced by more than 15%, and the relative standard deviation of all corrected values is less than 8%, and the correlation coefficient R 2 If it is greater than 0.98, the potential interfering element is determined to be an interfering element.

[0010] Furthermore, in step (1), an alloy element having an excitation potential of 4.3 to 5.5 eV and a first ionization energy of 7.5 to 8.5 eV is selected as a potential interfering element.

[0011] Furthermore, the Mg content in steps (2) and (3) is determined using a spark direct reading spectrometer, and the measurement parameters are: pre-combustion time of 15 s, integration time of 5 s, excitation energy of 400 V, and argon flow rate of 12 L / min.

[0012] In order to solve the above technical problems, the correction method of the present invention uses the interfering elements determined above: the interfering elements are used for correction during the determination of magnesium in nickel-based alloy by the direct reading spectrometer.

[0013] Furthermore, the translation correction or rotation correction method is determined based on the deviation change characteristics of each interference element.

[0014] Furthermore, it is characterized in that during the measurement process, the high intensity of Mg is set to 285456 and the low intensity is set to 30915.

[0015] The beneficial effects of the above technical solution are as follows: the present invention uses a factory-configured Mg working curve on a photoelectric direct-reading spectrometer to evaluate a series of standard samples with a gradient distribution of Mg content; by observing the analysis results, possible interfering elements are found, and then these interfering elements are added one by one, and the correction method is adjusted, and the changes in the evaluation results are continuously observed; after one experiment, when all the evaluation data show regular changes and are close to the standard values, the interfering elements and the corresponding correction methods can be determined, thereby further improving the accuracy of the analysis; and realizing the rapid and accurate determination of magnesium in nickel-based alloys.

[0016] The present invention utilizes a spark source atomic emission spectrometer to precisely determine and correct interfering elements in the magnesium determination process, re-optimizes and sets high and low content intensities, and realizes the rapid and accurate determination of magnesium in nickel-based alloys. Its precision and accuracy fully meet actual production needs.

[0017] The present invention significantly improves the determination accuracy of the Mg element by systematically adjusting the high and low strength setting values of the nickel-based alloy Mg working curve, and effectively solves the problem of inaccurate measurement results in the prior art.

[0018] This method enables rapid, low-cost, and low-pollution determination of Mg in nickel-based alloys, overcoming many drawbacks of traditional determination methods and providing strong technical support for nickel-based alloy production quality control and materials research. It also effectively improves the precision and accuracy of Mg determination in nickel-based alloys using the spectrometer's original calibration curve, enhancing both measurement efficiency and reliability. DETAILED DESCRIPTION

[0019] The present invention will be further described in detail below with reference to specific embodiments.

[0020] The determination and correction method of interfering elements in the determination of magnesium in nickel-based alloys by this direct reading spectrometer are as follows:

[0021] 1. Initial screening of interfering elements: Based on the common components of nickel-based alloys (Ni, Cr, Fe, Mo, Cu, Al, Ti, Nb, Co, W, Si, Mn, C, P, S, As, Hf, etc.), potential interfering elements are selected based on a comprehensive range of factors. From the perspective of element content, alloying elements with a content greater than 0.1wt% are selected; referring to the spectral line database, the spectral lines of each element near the Mg analysis line (279.077nm) are queried, and alloying elements with a close distance and a high degree of overlap with the Mg analysis line are selected; considering the excitation potential, alloying elements with an excitation potential close to that of Mg are selected, that is, alloying elements with an excitation potential of 4.3 to 5.5eV; based on the ionization energy, alloying elements with a first ionization energy of 7.5 to 8.5eV are selected. After screening based on the above four screening conditions, the potential interfering elements screened out are selected from one or more of Mo, Cr, Cu, Al, Si, As and Hf.

[0022] 2. Interference element determination process:

[0023] (1) Instrument preparation: Spark direct reading spectrometer, photoelectric direct reading spectrometer, atomic absorption spectrometer and vacuum direct reading spectrometer can be used; spark direct reading spectrometer is preferred.

[0024] The spark spectrometer is meticulously cleaned, including the lens and excitation stage, to ensure a clear optical path and a stable excitation environment. Intelligent standardization (iCAL) and drift correction are then performed to ensure optimal instrument performance and ensure accurate measurements.

[0025] (2) Determination steps: Select several standard samples with a Mg content gradient distribution between 0.0005% and 0.005wt% as a standard sample group. It is best to select at least 6 standard samples as a standard sample group. Use the original working curve to determine the Mg content of these standard samples, and accurately record the measurement results to obtain the standard value of each standard sample.

[0026] Correction items for potential interfering elements are added one by one to the standard sample set. After each addition, the standard samples are re-measured and the measurement results are recorded in detail. The specific process is as follows: each standard sample in each standard sample set is added with the same interfering element and measured separately. Then, a new standard sample set is added with a different interfering element and measured again. This is done until all potential interfering elements have been added and measured. After the measurement is completed, the corrected measurement value for each standard sample after adding each potential interfering element is obtained.

[0027] (3) Measurement parameters: A spark direct reading spectrometer was used, and the pre-combustion time was set to 15 s to fully excite the sample at the initial stage of excitation to ensure the stability of the test results; the integration time was 5 s to ensure that the spectral signal could be effectively collected; the excitation energy was 400 V and the argon flow rate was 12 L / min to provide a suitable energy and atmosphere environment for sample excitation.

[0028] 3. Interference element judgment standard: Compare the calibrated measured value with the standard value, analyze the deviation, and determine the interfering element based on the deviation change.

[0029] (1) Interference element determination criteria: After adding a certain element for correction, if the relative deviation of the test results of at least three standard samples from the standard value is reduced by more than 15%, and the relative standard deviation (RSD) of all standard samples after correction is less than 8%, and the correlation coefficient R of the working curve after correction is less than 10%. 2 If the value is greater than 0.98 and all three conditions are met at the same time, it means that the addition of the correction item of the element has a significant positive effect on the measurement results, effectively reduces the deviation, and improves the precision and correlation of the measurement. Therefore, if all three conditions are met, the potential interfering element is determined to be an interfering element.

[0030] (2) Non-interfering element determination conditions: After adding correction, if the test results do not improve significantly or deteriorate, and the correction term coefficient is not significant after statistical test, that is, p>0.05, then the potential interfering element is determined to be a non-interfering element. If there is a situation that does not meet the interfering element determination conditions and the non-interfering element determination conditions, it is necessary to re-examine the experimental process, including whether there are problems with sample preparation, instrument status, measurement parameters, etc. If the experiment is correct, the number of experiments and the number of samples can be increased for further judgment; the situation that meets both the interfering element determination conditions and the non-interfering element determination conditions usually does not occur. If it does, the experimental process needs to be re-examined to ensure the accuracy of the judgment.

[0031] (3) After analysis, it was determined that the seven elements Mo, Cr, Cu, Al, Si, As, and Hf were interfering elements. The interfering elements in the original calibration curve of Mg configured by the photoelectric direct reading spectrometer at the factory were Mo, Fe, and Ti. In the subsequent determination of magnesium in nickel-based alloys using the Huayuan atomic emission spectrometer, the additive correction terms of Fe and Ti were removed, and the seven elements Mo, Cr, Cu, Al, Si, As, and Hf were used as interfering elements.

[0032] Basis for removing Fe and Ti: Extensive experimental data indicates that adding Fe correction does not significantly improve test results, with p = 0.32 > 0.05. Furthermore, the overlap between the Fe characteristic line at 275.574nm and the Mg analytical line at 279.077nm is less than 5%, resulting in minimal interference with Mg testing. Regarding Ti, its characteristic line at 308.804nm is quite distant from the Mg analytical line, and the Ti content in nickel-based alloys is typically low, less than 0.3%. Therefore, considering these factors, the Fe and Ti correction terms can be removed.

[0033] 4. Method for determining the calibration method:

[0034] (1) Applicable conditions for translation correction: When the element content is linearly related to the Mg test deviation and the intensity value changes evenly before and after correction, the translation correction method is suitable. Analysis shows that Mo, Cr, Cu, and Hf elements meet this condition.

[0035] (2) Rotational correction applicable conditions: If the effect of an element on the Mg test results changes nonlinearly with the Mg content, and the slope of the working curve changes significantly before and after correction, then the rotational correction method is more appropriate. Analysis of Al, Si, and As elements meets this condition.

[0036] 5. Interference element correction method: In the process of determining magnesium in nickel-based alloys using Huayuan atomic emission spectrometer, the high intensity of Mg is set to 285456 and the low intensity is set to 30915. These two intensity setting values are obtained through testing a large number of standard samples and creative data analysis, which can effectively improve the accuracy of Mg element determination.

[0037] 6. Basis for selecting Mo / Cr / Cu / Al / Si / As / Hf: Through detailed analysis of spectral line interference data, it is found that the interference lines of Mo, Cr, Cu, Al, Si, As, and Hf are close to the Mg 279.077nm analysis line and have a high degree of overlap. The specific data are shown in Table 1 below:

[0038] Table 1: Mo / Cr / Cu / Al / Si / As / Hf interference lines

[0039]

[0040] 7. Correction formula for each interfering element:

[0041] (1) Translation correction:

[0042] Taking Mo as an example, the correction formula is: I{Mg_corrected} = I{Mg_measured} - k × [M]), where k is the correction factor and [M] is the interfering element content. The correction factor k is derived by fitting a large amount of experimental data. The value of k varies for different interfering elements. For example, the correction factor k for Mo has been repeatedly verified and determined to be 0.15 in experiments.

[0043] (2) Rotation Correction: Taking Al as an example, the correction formula is: I_{Al_corrected} = I_{Al_measured} / (1 + α × [M]), where α is the rotation factor and [M] is the interfering element content. Similarly, the rotation factor α must also be determined based on experimental data. For example, for Al, α has been experimentally determined to be 0.35.

[0044] Note: The correction factor needs to be determined by fitting with standard samples and may vary slightly between different instruments.

[0045] Example 1:

[0046] 1. Preparation: First, thoroughly clean the spectrometer's lenses and excitation stage to remove dust and impurities from the surface to ensure a clear optical path and stable excitation. Next, perform intelligent standardization (iCAL) to restore all instrument parameters to standard conditions. Drift correction is then performed to ensure measurement accuracy.

[0047] 2. Test process: Six nickel-based alloy standard samples with gradient Mg content were used, and their contents are shown in Table 2 below:

[0048] Table 2: Mg content in the standard sample of Example 1

[0049] Standard sample number Mg element content (wt%) 1# 0.0032 2# 0.0035 3# 0.0068 4# 0.0071 5# 0.022 6# 0.053

[0050] The Mg content in the nickel-based alloy was tested using the nickel-based original working curve. The test results are shown in Table 3 below:

[0051] Table 3: Measurement results of Example 1

[0052] Standard sample number Standard value (wt%) Corrected measured value (wt%) 1# 0.0032 0.0045 2# 0.0035 0.0021 3# 0.0068 0.0068 4# 0.0071 0.0124 5# 0.0220 0.0176 6# 0.0530 0.0543

[0053] 3. Interference element correction process:

[0054] (1) Removal of Fe and Ti correction items: Since the overlapping interference of Fe275.574nm and Ti308.804nm on the Mg279.077nm channel in the original working curve analysis program of nickel-based Ni30 is extremely small, after removing the additive correction items of Fe and Ti, the Mg element determination results are shown in Table 4 below:

[0055] Table 4: Corrected results of Example 1 after removal of Fe and Ti

[0056]

[0057]

[0058] (2) Preliminary calibration: Find the sensitive lines and excitation potentials of various elements in the nickel-based alloy steel to be tested, and determine that the elements that may interfere with the Mg element are Mo / Cr / Cu / Al / Si / As / Hf; set the calibration mode to translation calibration, and perform sample measurement. The results are shown in Table 5 below:

[0059] Table 5: Results after translation correction

[0060] Standard sample number Standard value (%) Measured value (%) 1# 0.0032 0.0064 2# 0.0033 0.0024 3# 0.0068 0.0042 4# 0.0071 0.079 5# 0.0220 0.0232 6# 0.0530 0.0368

[0061] (2) Optimization correction: According to the relationship between interfering elements and Mg test deviation, the correction method of Mo, Cr, Cu, and Hf was changed to translation correction, and the correction method of Al, Si, and As was changed to rotation correction. The test was repeated, and the results are shown in Table 6 below:

[0062] Table 6: Results after optimization and correction

[0063] Standard sample number Standard value (%) Measured value (%) 1# 0.0032 0.0031 2# 0.0035 0.0035 3# 0.0068 0.0068 4# 0.0071 0.0073 5# 0.0220 0.0224 6# 0.0530 0.0537

[0064] (3) By comparison, it can be found that after adjusting the interference correction element and the correction method, the deviation between the measured value and the standard value is within the allowable range of the material, and the accuracy is significantly improved. This fully verifies the effectiveness and reliability of the method of the present invention, and it can accurately determine the content of magnesium in nickel-based alloys in actual production and material research.

[0065] Example 2:

[0066] 1. Experimental Materials Preparation Another batch of nickel-based alloy standard samples with different composition ratios were selected, a total of 6, and their Mg element content gradient distribution is shown in Table 7:

[0067] Table 7: Mg content in the standard sample of Example 2

[0068] Standard sample number Mg element content (wt%) 7# 0.0010 8# 0.0025 9# 0.0040 10# 0.0055 11# 0.0070 12# 0.0085

[0069] 2. Instrument Preparation and Initial Testing: Clean the lens and excitation stage of the spark spectrometer, complete intelligent standardization (iCAL) and drift correction, and use the original working curve to test the Mg content of the six standard samples. The results are recorded in Table 8 below:

[0070] Table 8: Measurement results of Example 2

[0071] Standard sample number Standard value (%) Measured value (%) 7# 0.0010 0.0018 8# 0.0025 0.0032 9# 0.0040 0.0050 10# 0.0055 0.0070 11# 0.0070 0.0085 12# 0.0085 0.0100

[0072] Calculate the relative deviation between each measured value and the standard value. For example, the relative deviation of sample 7# is (0.0018-0.0010)÷0.0010×100%=80%. The same applies to other samples. It is found that the relative deviation is large, indicating that the original working curve measurement is inaccurate.

[0073] 3. Interference element determination and correction process:

[0074] According to the interfering element screening method described in this method, the potential interfering elements were determined to be Mo, Cr, Cu, Al, Si, As, and Hf. The Fe and Ti correction items were first removed (according to the original Example 1), and then the potential interfering element correction items were added one by one for testing.

[0075] Taking the addition of the Mo correction term as an example, with a Mo content of 2.0% and an analytical line of Mo at 281.615 nm, the translation correction formula is I_{Mg_corrected} = I_{Mg_measured} - 0.18 × I_{Mo}. The correction factor of 0.18 is obtained by fitting the standard sample test data in this experiment. The changes in the test data for some samples after adding the Mo correction term in this example are shown in Table 9:

[0076] Table 9: Test data of some samples after adding Mo correction term in Example 2

[0077] Standard sample number Uncorrected measured value (%) Corrected measured value (%) 7# 0.0018 0.0014 8# 0.0032 0.0027

[0078] After adding other interfering element correction items, the impact of each element on the Mg content test results was comprehensively judged. According to the interfering element judgment criteria, Mo, Cr, Cu, and Hf were determined to use translation correction, while Al, Si, and As were determined to use rotation correction. The final corrected test results are as follows10:

[0079] Table 10: Calibration results of Example 2

[0080] Standard sample number Standard value (%) Corrected measured value (%) 7# 0.0010 0.0011 8# 0.0025 0.0026 9# 0.0040 0.0041 10# 0.0055 0.0056 11# 0.0070 0.0072 12# 0.0085 0.0087

[0081] Calculate the relative deviation of each measured value and the standard value after correction. For example, the relative deviation of sample 7# is (0.0011-0.0010)÷0.0010×100%=10%. The relative deviations of other samples are also within a small range. And the relative standard deviation (RSD) of all standard samples after correction is 5.5%<8%. The correlation coefficient R of the working curve after correction is 2 =0.99>0.98, meeting the accuracy requirement after correction of interfering elements.

[0082] This implementation case once again verified the effectiveness of this interfering element determination and correction method in different nickel-based alloy samples, and can significantly improve the accuracy of spark direct reading spectrometer in determining the magnesium content in nickel-based alloys.

Claims

1. A method for determining interfering elements in magnesium in nickel-based alloys using a direct reading spectrometer, characterized in that: The method comprises the following steps: (1) selecting alloying elements with a content of >0.1% in nickel-based alloys as potential interfering elements; (2) Using a standard sample set containing a gradient of Mg content, the Mg content was determined using a direct reading spectrometer to obtain the standard value of each standard sample; (3) Add correction items of potential interfering elements one by one to the standard sample group, and use direct reading spectrometer to determine the Mg content, and obtain the corrected measurement value of each standard sample after adding each potential interfering element; (4) After adding a potential interfering element for correction, if the relative deviation between the corrected measured values and the standard values of at least three standard samples decreases by more than 15%, and the relative standard deviation of all corrected measured values is less than 8%, and the correlation coefficient R 2 If it is greater than 0.98, the potential interfering element is determined to be an interfering element.

2. The method for determining the interfering elements of magnesium in nickel-based alloys by direct reading spectrometer according to claim 1, characterized in that: In the step (1), an alloy element having an excitation potential of 4.3 to 5.5 eV and a first ionization energy of 7.5 to 8.5 eV is selected as a potential interfering element.

3. The method for determining the interfering elements of magnesium in nickel-based alloys by direct reading spectrometer according to claim 1 or 2, characterized in that: In both steps (2) and (3), a spark direct reading spectrometer is used to determine the Mg content, and the measurement parameters are: pre-combustion time is 15 s, integration time is 5 s, excitation energy is 400 V, and argon flow rate is 12 L / min.

4. A method for correcting interfering elements in the determination of magnesium in nickel-based alloys by direct reading spectrometer, using the interfering elements determined in claim 1, characterized in that: The interfering element is used for correction in the process of determining magnesium in nickel-based alloy by the direct reading spectrometer.

5. The interfering element correction method for determining magnesium in nickel-based alloys by direct-reading spectrometer according to claim 4, characterized in that: The translation correction or rotation correction method is determined based on the deviation change characteristics of each interference element.

6. The interfering element correction method for determining magnesium in nickel-based alloys by direct-reading spectrometer according to claim 4 or 5, characterized in that: During the measurement, the high intensity of Mg was set to 285456 and the low intensity was set to 30915.

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