Method for detecting trace oxygen element based on electron probe microanalyzer

Abstract

This application discloses a method for detecting trace oxygen elements based on an electron probe microanalyzer, relating to the field of analytical detection technology. The method includes: placing the sample to be tested in the electron probe microanalyzer to obtain the signal intensity of oxygen and the signal intensity of major elements in the sample; obtaining the theoretical standard content of oxygen in a standard sample calculated by the built-in calculator of the electron probe microanalyzer; determining a total correction factor based on the signal intensity of oxygen and the signal intensity of major elements; and determining the oxygen content in the sample based on the total correction factor, the theoretical standard content of oxygen in the standard sample calculated by the built-in calculator, and the signal intensity of oxygen. This application solves the technical problem of insufficient accuracy in detecting trace oxygen content in samples using electron probe microanalyzers.

Description

Technical Field

[0001] This application relates to the field of analytical testing technology, and in particular to a method for detecting trace oxygen elements based on an electron probe microanalyzer. Background Technology

[0002] EPMA (Electron Probe Microanalyzer) is an important tool for characterizing the composition of micromaterials, especially in the quantitative analysis of trace light elements. However, the accurate quantitative analysis of trace oxygen elements (1%-10% by mass) in material samples has long faced many technical challenges.

[0003] Currently, the determination of oxygen content is closely related to its form in the sample. In most cases, the state of trace oxygen is unknown. Traditional methods rely on physical oxide standards (such as Al2O3 and TiO2). The form of oxygen in the standard is difficult to match with the form of oxygen in the sample to be tested, which can easily introduce human judgment error and lead to inaccurate determination of oxygen content in the sample. Summary of the Invention

[0004] The main objective of this application is to provide a method for detecting trace oxygen elements based on an electron probe microanalyzer, aiming to solve the technical problem that the electron probe microanalyzer is not accurate enough in detecting the content of trace oxygen elements in samples.

[0005] To achieve the above objectives, this application provides a method for detecting trace oxygen elements based on an electron probe microanalyzer, the method comprising: The sample to be tested is placed in an electron probe microanalyzer to obtain the signal intensity of oxygen and the signal intensity of major elements in the sample. Obtain the theoretical standard content of oxygen in the standard sample calculated by the built-in calculation function of the electron probe microanalyzer; The total correction factor is determined based on the signal intensity of the oxygen element and the signal intensity of the major elements. The oxygen content in the sample to be tested is determined based on the total correction factor, the theoretical standard content of oxygen in the built-in calculated standard sample, and the signal intensity of oxygen.

[0006] In a feasible embodiment, the step of determining the total correction factor based on the signal intensity of the oxygen element and the signal intensity of the major elements includes: Based on the signal intensity of oxygen and the signal intensity of major elements, the atomic number correction coefficient, absorption correction coefficient and light element correction coefficient of the sample to be tested are determined, wherein the absorption correction coefficient is determined based on the integral of the depth distribution function of each element in the sample to be tested; Calculate the total correction factor based on the atomic number correction factor, the absorption correction factor, and the light element correction factor; The oxygen content in the sample to be tested is determined based on the total correction factor, the theoretical standard content of oxygen in the built-in calculated standard sample, and the signal intensity of oxygen.

[0007] In one feasible embodiment, prior to the step of placing the sample to be tested in an electron probe microanalyzer to obtain the signal intensity of oxygen and the signal intensity of major elements in the sample, the method further includes: The sample to be tested was subjected to ion polishing.

[0008] In one feasible embodiment, the voltage for ion polishing is 4 kV to 8 kV, the ion beam incident angle is 2° to 5°, the sample stage rotation speed is 3 rpm to 6 rpm, and the polishing time is 10 min to 20 min.

[0009] In one feasible embodiment, the ion source for the ion polishing includes an argon ion beam.

[0010] In one feasible embodiment, the surface roughness Ra of the sample to be tested after ion polishing is ≤ 100 nm.

[0011] In one feasible embodiment, the ion-polished sample is transferred to an electron probe microanalyzer for testing within 3 minutes. Alternatively, the test sample, after ion polishing, can be placed in a vacuum of less than or equal to 1 x 10⁻⁶. -3 Saved in the environment of Pa.

[0012] In one feasible embodiment, the accelerating voltage of the electron probe microanalyzer is 15 kV~20 kV, the beam current is 20 nA~100 nA, and the peak position testing time for oxygen is 10 s~20 s.

[0013] In one feasible embodiment, the sample to be tested includes at least one of powder, bulk and film; And / or, the resistivity of the sample to be tested is less than 100 Ω·cm; And / or, the oxygen content in the sample to be tested is greater than or equal to 100 ppm.

[0014] In one feasible embodiment, the principal element includes at least one of the following: The element present in the sample to be tested at a concentration greater than or equal to 20%; Elements with atomic number Z ≤ 17.

[0015] This application discloses a method for detecting trace oxygen based on an electron probe microanalyzer. First, the sample to be tested is placed in the electron probe microanalyzer to obtain the signal intensity of oxygen and the signal intensity of major elements in the sample. By simultaneously measuring the signal intensities of oxygen and major elements, the absorption effect of major elements on oxygen characteristic X-rays is effectively corrected, avoiding the possibility of underestimating oxygen content due to neglecting the absorption effect. Second, the theoretical standard content of oxygen in the built-in calculated standard sample of the electron probe microanalyzer is obtained. Using the built-in calculated standard sample of the electron probe microanalyzer to obtain the theoretical standard content of oxygen in the built-in calculated standard sample does not rely on physical standard samples, avoiding measurement errors introduced by the mismatch between the form of oxygen in traditional physical standard samples and the sample to be tested. During the calculation process, the built-in calculated standard sample can back-calculate the effective standard sample content based on the current matrix conditions of the sample to be tested, achieving adaptive matching and providing a stable reference for the quantitative analysis of trace oxygen. Furthermore, based on the signal intensity of oxygen and the signal intensity of major elements, a total correction factor is determined. Then, based on the total correction factor, the theoretical standard content of oxygen in the built-in calculated standard, and the signal intensity of oxygen, the oxygen content in the sample to be tested is determined. This avoids the limitations of relying on empirical correction or external standards for the detection of trace oxygen, achieving a matching solution between oxygen content and matrix composition, and effectively increasing the accuracy of oxygen content detection in samples during electron probe microscopy analysis. Attached Figure Description

[0016] Figure 1 This is a schematic flowchart of the method for detecting trace oxygen elements based on an electron probe microanalyzer according to an embodiment of this application. Figure 2 This is a schematic diagram of the ion polishing treatment performed on the sample to be tested according to an embodiment of this application; Figure 3 This is a schematic diagram of the oxygen absorption effect during the detection of oxygen content in the sample to be tested, as described in the embodiments of this application.

[0017] The realization of the purpose, functional features and advantages of this application will be further explained in conjunction with the embodiments and with reference to the accompanying drawings. Detailed Implementation

[0018] To make the objectives, technical solutions, and advantages of the embodiments of this application clearer, the technical solutions in the embodiments of this application will be clearly and completely described below. Where specific conditions are not specified in the embodiments, conventional conditions or conditions recommended by the manufacturer shall apply. Reagents or instruments whose manufacturers are not specified are all conventional products that can be purchased commercially.

[0019] The "range" disclosed in this application is defined by a lower limit and an upper limit. A given range is defined by selecting a lower limit and an upper limit, which define the boundaries of a particular range. Ranges defined in this way can include or exclude endpoints and can be arbitrarily combined; that is, any lower limit can be combined with any upper limit to form a range. For example, if ranges of 60~120 and 80~110 are listed for a specific parameter, it is also expected that ranges of 60~110 and 80~120 are also included. Furthermore, if minimum range values ​​of 1 and 2 are listed, and if maximum range values ​​of 3, 4, and 5 are listed, then the following ranges are all expected: 1~3, 1~4, 1~5, 2~3, 2~4, and 2~5. In this application, unless otherwise stated, the numerical range "a~b" represents a shortened representation of any combination of real numbers between a and b, where a and b are real numbers. For example, the numerical range "0~5" indicates that all real numbers between "0~5" have been listed in this article; "0~5" is simply a shortened representation of these numerical combinations. Furthermore, when a parameter is stated as an integer ≥2, it is equivalent to disclosing that the parameter is, for example, an integer such as 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, etc.

[0020] Unless otherwise specified, all embodiments and optional embodiments of this application can be combined to form new technical solutions.

[0021] Unless otherwise specified, all technical features and optional technical features of this application may be combined to form new technical solutions.

[0022] Unless otherwise specified, all steps in this application may be performed sequentially or randomly, preferably sequentially. For example, if the method includes steps (a) and (b), it means that the method may include steps (a) and (b) performed sequentially, or it may include steps (b) and (a) performed sequentially. For example, if the method may also include step (c), it means that step (c) may be added to the method in any order. For example, the method may include steps (a), (b), and (c), or it may include steps (a), (c), and (b), or it may include steps (c), (a), and (b), etc.

[0023] Unless otherwise specified, the terms "comprising" and "including" as used in this application can be open-ended or closed-ended. For example, "comprising" and "including" can mean that other components not listed may also be included, or that only the listed components may be included.

[0024] Unless otherwise specified, the term "or" is inclusive in this application. For example, the phrase "A or B" means "A, B, or both A and B". More specifically, the condition "A or B" is satisfied by any of the following conditions: A is true (or exists) and B is false (or does not exist); A is false (or does not exist) and B is true (or exists); or both A and B are true (or exist).

[0025] To make the above-mentioned objectives, features, and advantages of this application more apparent and understandable, the technical solution of this application is further described below in conjunction with the accompanying drawings and embodiments. However, this application is not limited to the listed embodiments, but should also include any other well-known modifications within the scope of the claims made in this application.

[0026] The term "an embodiment" or "embodiment" as used herein refers to a specific feature, structure, or characteristic that may be included in at least one implementation of this application. The phrase "in one embodiment" appearing in different places throughout this specification does not necessarily refer to the same embodiment, nor is it a single or selective embodiment that is mutually exclusive with other embodiments.

[0027] Currently, the determination of oxygen content is closely related to its form in the sample. In most cases, the state of trace oxygen is unknown. Traditional methods rely on physical oxide standards (such as Al2O3 and TiO2). The form of oxygen in the standard is difficult to match with the form of oxygen in the sample to be tested, which can easily introduce human judgment error and lead to inaccurate determination of oxygen content in the sample.

[0028] This application discloses a method for detecting trace oxygen based on an electron probe microanalyzer. First, the sample to be tested is placed in the electron probe microanalyzer to obtain the signal intensity of oxygen and the signal intensity of major elements in the sample. By simultaneously measuring the signal intensities of oxygen and major elements, the absorption effect of major elements on oxygen characteristic X-rays is effectively corrected, avoiding the possibility of underestimating oxygen content due to neglecting the absorption effect. Second, the theoretical standard content of oxygen in the built-in calculated standard sample of the electron probe microanalyzer is obtained. Using the built-in calculated standard sample of the electron probe microanalyzer to obtain the theoretical standard content of oxygen in the built-in calculated standard sample does not rely on physical standard samples, avoiding measurement errors introduced by the mismatch between the form of oxygen in traditional physical standard samples and the sample to be tested. During the calculation process, the built-in calculated standard sample can back-calculate the effective standard sample content based on the current matrix conditions of the sample to be tested, achieving adaptive matching and providing a stable reference for the quantitative analysis of trace oxygen. Furthermore, based on the signal intensity of oxygen, the signal intensity of the major elements, and the theoretical standard content of oxygen in the built-in calculated standard sample, the oxygen content in the sample to be tested is obtained. This achieves a matching solution between oxygen content and matrix composition, effectively increasing the accuracy of oxygen content detection in samples during electron probe microscopy analysis.

[0029] This application provides a method for detecting trace oxygen content based on an electron probe microanalyzer, referring to... Figure 1 The method for detecting trace oxygen content includes the following steps: Step S10: Place the sample to be tested in an electron probe microanalyzer to obtain the signal intensity of oxygen and the signal intensity of major elements in the sample. In one feasible embodiment, the sample to be tested is placed in an EPMA, and the characteristic X-ray signal intensities of oxygen and major elements are acquired simultaneously. By forcibly and synchronously determining the major elements, the necessary matrix composition information is provided for subsequent matrix effect correction.

[0030] In one feasible embodiment, the sample to be analyzed is prepared, ensuring that the sample surface meets the analytical requirements.

[0031] Optionally, depending on the type of the sample to be tested, the sample may be inlaid and manually polished to ensure that the surface of the sample is clean and free of scratches, with a surface roughness Ra ≤ 0.01 mm.

[0032] In one feasible implementation, the sample to be tested includes at least one of powder, bulk and film; Optionally, powder samples (such as metal powders for additive manufacturing) need to be pressed or mounted before testing; bulk samples (such as metal blocks or alloy castings) can be directly mounted or placed directly on the sample stage for testing; thin film samples (such as coatings or platings) need to ensure sufficient thickness to generate a stable X-ray signal.

[0033] In one feasible implementation, the resistivity of the sample to be tested is less than 100 Ω·cm; The sample's resistivity is less than 100 Ω·cm, indicating that the sample has good conductivity. In this embodiment, electron probe microscopy requires the sample to be conductive to avoid charge accumulation during electron beam bombardment, which could lead to signal drift, image distortion, or even sample damage.

[0034] Optionally, in a feasible implementation, the oxygen content in the sample to be tested is greater than or equal to 100 ppm.

[0035] Optionally, optimizations can be made for the determination of trace oxygen, covering the full range from ultra-trace oxygen to conventional trace oxygen. For oxygen contents below 100 ppm, measurement accuracy may be insufficient due to the detection limit of EPMA.

[0036] In one feasible implementation, before the step of placing the sample to be tested in an electron probe microanalyzer to obtain the signal intensity of oxygen and the signal intensity of major elements in the sample, the method further includes: The sample to be tested was subjected to ion polishing.

[0037] In a feasible embodiment, EPMA testing requires the test surface of the sample to be as smooth and flat as possible. Ion polishing aims to remove surface oxygen interference, not to etch away surface material. During conventional mechanical polishing, the sample surface adsorbs oxygen molecules from the air, forming an oxide layer or adsorbed layer with a thickness on the nanometer scale. Surface adsorbed oxygen is not the intrinsic oxygen content of the sample and will lead to falsely high oxygen content measurements in EPMA testing. Conventional cleaning methods (such as ultrasonic cleaning) cannot effectively remove chemically adsorbed oxygen from the surface.

[0038] Optionally, refer to Figure 2 Argon ion beam is used as the ion source. The sample to be tested is placed on the sample area of ​​the sample stage. By rotating the sample stage, the sample area is ion polished. The incident angle of the ion beam is 3°.

[0039] Optionally, refer to Figure 3 The black horizontal line represents the surface of the sample to be tested. The regularly arranged green circles below the line represent other elements inside the sample. The yellow and blue circles above the line represent oxygen and water molecules adsorbed on the sample surface, which has been polished; the yellow circle below represents oxygen in the sample. The red circle represents argon ions, which expel surface oxygen atoms or molecules through momentum transfer when the argon ion beam bombards the sample surface. The yellow converging beam represents the incident electron beam of the electron probe microanalyzer. When the electron beam irradiates the sample surface, it excites characteristic X-ray signals corresponding to the sample atoms. As the signal excited by the oxygen atoms propagates through the sample, other elements inside the sample absorb the oxygen signal. Finally, the signal is transmitted to the signal acquisition module for acquisition and subsequent calculation of the oxygen content.

[0040] In one feasible implementation, the voltage for theoretical standard content ion polishing is 4 kV~8 kV, the ion beam incident angle is 2°~5°, the sample stage rotation speed is 3 rpm~6 rpm, and the polishing time is 10 min~20 min. Optionally, the voltage for ion polishing can be 4 kV, 5 kV, 6 kV, 7 kV, 8 kV, etc. If the voltage is too low, the ion energy is insufficient, resulting in low sputtering efficiency and difficulty in removing surface-adsorbed oxygen; if the voltage is too high, the ion energy is too high, which may cause sample surface damage, ion implantation, or amorphization. A voltage in the range of 4 kV to 8 kV can achieve gentle cleaning, removing surface oxygen while maintaining the integrity of the sample surface.

[0041] Optionally, the ion beam incident angle for ion polishing can be 2°, 3°, 4°, 5°, etc. At small incident angles, the interaction depth between the ion beam and the sample surface is shallow, mainly acting on the outermost atoms, which is beneficial for removing surface-adsorbed oxygen without affecting the deeper structure of the sample. If the angle is too small, the sputtering efficiency is too low, resulting in poor cleaning; if the angle is too large, it may cause surface roughening, affecting subsequent EPMA testing.

[0042] Optionally, the stage rotation speed for ion polishing can be 3 rpm, 4 rpm, 5 rpm, 6 rpm, etc. Stage rotation causes the ion beam to bombard the sample from different directions, ensuring uniform surface cleaning. Too low a rotation speed results in poor cleaning uniformity and may produce directional marks; too high a rotation speed may cause mechanical vibration, affecting the polishing effect.

[0043] Optionally, the polishing time for ion polishing can be 10 min, 11 min, 12 min, 13 min, 14 min, 15 min, 16 min, 17 min, 18 min, 19 min, 20 min, etc. If the ion polishing time is too short, the sample to be tested will not be thoroughly cleaned, and oxygen will remain on the surface; if the ion polishing time is too long, the sample surface layer may be etched away, changing the intrinsic oxygen content of the sample.

[0044] In one feasible implementation, the ion source for ion polishing includes an argon ion beam.

[0045] Alternatively, argon is an inert gas that does not participate in chemical reactions and will not introduce new polluting elements into the sample to be tested.

[0046] In one feasible implementation, the surface roughness Ra of the sample to be tested after ion polishing is ≤ 100 nm.

[0047] In one feasible embodiment, when the surface of the sample to be tested is uneven, protrusions at the electron beam bombardment point and along the X-ray emission path can partially block the X-ray signal. Furthermore, the rough surface results in an actual analytical area larger than the beam spot diameter, reducing spatial resolution. Controlling the surface roughness of the sample after ion polishing can effectively avoid the aforementioned geometric shading effect, ensuring accurate acquisition of X-ray signal intensity, maintaining the high spatial resolution of the electron probe microanalyzer, and thus improving the accuracy and repeatability of trace oxygen content determination.

[0048] In one feasible embodiment, the ion-polished sample is transferred to an electron probe microanalyzer for testing within 3 minutes; Alternatively, the sample to be tested, after ion polishing, can be placed in a vacuum of less than or equal to 1×10⁻⁶. -3 Saved in the environment of Pa.

[0049] In one feasible embodiment, ion polishing removes the layer of adsorbed oxygen atoms from the sample surface by bombarding it with an argon ion beam. The treated surface is in a highly active state, with numerous unsaturated dangling bonds on its atoms. If exposed to air, oxygen molecules in the environment will rapidly recombine with the surface atoms, leading to oxygen re-adsorption. Therefore, the environmental conditions of the sample must be strictly controlled after ion polishing to ensure that the surface oxygen removal effect is maintained until the EPMA test is completed.

[0050] Optionally, during the rapid re-adsorption period of oxygen on the surface after ion polishing, the adsorption rate is fastest in the first 3 minutes. Therefore, performing subsequent EPMA tests within 3 minutes can maximize the polishing effect of the sample surface.

[0051] Alternatively, vacuum preservation is achieved by reducing the ambient air pressure to suppress surface re-adsorption and isolating the surface of the sample from oxygen molecules.

[0052] This embodiment effectively suppresses surface oxygen re-adsorption by employing a transfer test within 3 minutes or high vacuum preservation, ensuring that the oxygen coverage of the sample surface is close to the initial state after ion polishing during the test. The test signal reflects the intrinsic oxygen content of the sample, avoiding falsely high measurement results caused by surface oxygen re-adsorption.

[0053] In one feasible implementation, the accelerating voltage of the electron probe microanalyzer is 15 kV~20 kV, the beam current is 20 nA~100 nA, and the peak position testing time for oxygen is 10 s~20 s.

[0054] Optionally, the accelerating voltage of the electron probe microanalyzer can be 15 kV, 16 kV, 17 kV, 18 kV, 19 kV, 20 kV, etc. The accelerating voltage determines the kinetic energy of the incident electrons and the penetration depth in the sample. When the accelerating voltage is too low, the penetration depth is too shallow, and the electron beam mainly acts on the outermost layer of the sample. The interference from surface-adsorbed oxygen is significantly enhanced, making it difficult to reflect the intrinsic oxygen content of the sample. At the same time, an excessively low accelerating voltage cannot excite the threshold voltage of the main element, resulting in no signal of the main element or an extremely low signal. When the accelerating voltage is too high, the penetration depth increases rapidly, the analysis area expands, and the spatial resolution decreases, making it difficult to meet the needs of micro-area analysis. In addition, an excessively deep penetration depth will introduce more matrix interference, increasing the uncertainty of absorption correction.

[0055] Optionally, the beam current of the electron probe microanalyzer can be 20 nA, 30 nA, 40 nA, 50 nA, 60 nA, 70 nA, 80 nA, 90 nA, 100 nA, etc. When the beam current is too low, the oxygen count rate is too low, making it difficult to meet the requirements for accurate quantification of trace oxygen; when the beam current is too high, the electron beam energy density increases, which may lead to localized heating of the sample surface, making it particularly sensitive to light elements such as oxygen, potentially causing oxygen volatilization or migration. Simultaneously, when the beam current is too high, the beam spot size is too large, which will significantly reduce the spatial resolution of the electron probe.

[0056] Optionally, the peak position testing time for oxygen element in the electron probe microanalyzer can be 10 s, 11 s, 12 s, 13 s, 14 s, 15 s, 16 s, 17 s, 18 s, 19 s, or 20 s. If the peak position testing time is too long, the efficiency of batch sample testing will decrease significantly, and at the same time, it will increase the statistical error to some extent.

[0057] Step S20: Obtain the theoretical standard content of oxygen in the standard sample calculated by the built-in calculation function of the electron probe microanalyzer; In one feasible embodiment, the theoretical standard content of oxygen is obtained by using a standard sample calculated within the EPMA. This theoretical standard content is a fixed constant calculated based on a physical model (oxygen content in pure oxygen is 100%), independent of physical standard samples, providing a stable and reliable benchmark for quantitative analysis.

[0058] Alternatively, the built-in computational standard is typically the result of fitting the electron probe microscope to a sufficiently large database before the device leaves the factory.

[0059] For example, the theoretical standard content of oxygen in the built-in calculated standard sample can be expressed as C. std .

[0060] Step S30: Determine the total correction factor based on the signal intensity of oxygen and the signal intensity of major elements; In a feasible embodiment, by integrating the signal intensities of oxygen and major elements measured in step S10 and the theoretical standard content of oxygen in the built-in calculated standard obtained in step S20, and combining them with a preset calibration quantification method, the accurate content of oxygen in the sample to be tested is finally calculated. Specifically, the physical parameters of the sample matrix are determined by using the signal intensity of major elements, and then the total correction factor is calculated. Finally, by solving for the content of oxygen in the sample to be tested, a self-consistent solution of oxygen content and matrix composition is achieved.

[0061] In one feasible implementation, the pre-defined calibration quantification method for the theoretical standard content includes PRZ.

[0062] In one feasible embodiment, the PRZ quantitative calibration method is a matrix effect correction method based on the X-ray depth distribution function. It simultaneously handles atomic number effects and absorption effects through an integral function, achieving accurate quantitative analysis of elemental content in a sample. Oxygen is a light element (Z=8), with low X-ray yield and strong absorption, making accurate correction difficult with traditional ZAF methods. The PRZ method, through integral function optimization, can more accurately describe the X-ray generation and transmission process of oxygen.

[0063] In one feasible implementation, step S30, which determines the total correction factor based on the signal intensity of the oxygen element and the signal intensity of the major elements, includes: Step S31: Based on the signal intensity of the oxygen element and the signal intensity of the major elements, determine the atomic number correction coefficient, absorption correction coefficient and light element correction coefficient of the sample to be tested, wherein the absorption correction coefficient is determined based on the integral of the depth distribution function of each element in the sample to be tested. In one feasible embodiment, in electron probe microanalysis (EPMA), the measured X-ray signal intensity cannot be directly equated to elemental content because the matrix of the sample under test has complex effects on the generation and emission of X-rays. By establishing a correction coefficient, the measured signal intensity is converted into the true content after matrix correction.

[0064] For example, taking the PRZ method as an example, The absorption correction coefficient is calculated by integrating the depth distribution function of the PRZ. This is the atomic number correction factor. The correction coefficients for light elements are obtained using the following formulas:

[0065]

[0066] in, This represents the X-ray depth distribution function of the sample under test. The X-ray depth distribution function of the standard sample. The angle between the direction of X-ray emission from the sample surface and the sample surface is represented by μ, which represents the linear absorption coefficient, and the unit is cm. - ¹ represents the probability of X-ray absorption per unit length of path; ρ represents the density of the material, in g / cm³. 3 .

[0067] Step S32: Calculate the total correction factor based on the atomic number correction coefficient, the absorption correction coefficient, and the light element correction coefficient; For example, taking the PRZ method, the total correction factor refers to the comprehensive coefficient used in the pre-defined quantitative correction method to correct matrix effects. The total correction factor Fo can be calculated by substituting the corresponding values ​​obtained during the sample testing process into the following formula:

[0068] in, This represents the effective scattering area of ​​an element.

[0069] Step S40: Determine the oxygen content in the sample to be tested based on the total correction factor, the theoretical standard content of oxygen in the built-in calculated standard sample, and the signal intensity of oxygen.

[0070] Optionally, taking the PRZ method as an example, the theoretical standard content C of oxygen in the standard sample is calculated internally. std The calculation is usually the result of fitting a sufficiently large database before the electron probe analyzer leaves the factory, but it can be derived using the following formula. :

[0071] in, This is the correction factor given to the instrument.

[0072] Inverse reasoning It can be inferred that by using the theoretical standard content of oxygen in the built-in calculation standard sample, a corresponding standard content reference value can be generated by automatically fitting a close approximation of the collected oxygen signal and the corresponding environment of the oxygen element, even when the form in which oxygen exists is unknown. This allows for the generation of the aforementioned... F O numerical sum Substituting the numerical value into the following formula, the oxygen content C in the sample can be obtained. O :

[0073] Where, k O This indicates the ratio of the measured oxygen signal intensity.

[0074] In one feasible implementation, the principal element includes at least one of the following: Elements present in the sample at a concentration of 20% or higher; Elements with atomic number Z ≤ 17.

[0075] In one feasible embodiment, a major element refers to an element present in high concentrations in the sample that significantly influences matrix effects (particularly absorption effects). The selection of major elements is crucial for the accurate determination of trace oxygen, as their absorption effect on characteristic X-rays of oxygen directly affects the quantitative accuracy of oxygen content.

[0076] Optionally, when the element content is below 20%, its contribution to the average atomic number of the sample to be tested is small, and its contribution to the mass absorption coefficient is also small, which can be ignored. When the element content is below 20%, its contribution to the mass absorption coefficient is small for most elements, accounting for a small proportion of the total absorption coefficient, and its effect on absorption correction can be ignored.

[0077] Optionally, elements with atomic numbers Z ≤ 17 refer to elements with atomic numbers less than or equal to 17. Elements with atomic numbers close to oxygen will exhibit a significant absorption effect, affecting the detection results of oxygen content. Elements with atomic numbers Z ≤ 17 belong to the categories of light and medium-light elements. These elements have low characteristic X-ray energies, requiring special testing conditions and calibration methods in EPMA analysis. For oxygen determination, these elements are both potential matrix components and strongly absorb oxygen signals; therefore, they must be included in the major element determination range.

[0078] This embodiment discloses a method for detecting trace oxygen based on an electron probe microanalyzer. First, the sample to be tested is placed in the electron probe microanalyzer to obtain the signal intensity of oxygen and the signal intensity of major elements in the sample. By simultaneously measuring the signal intensities of oxygen and major elements, the absorption effect of major elements on oxygen characteristic X-rays is effectively corrected, avoiding the possibility of underestimating oxygen content due to neglecting the absorption effect. Second, the theoretical standard content of oxygen in the built-in calculated standard sample of the electron probe microanalyzer is obtained. Using the built-in calculated standard sample of the electron probe microanalyzer to obtain the theoretical standard content of oxygen in the built-in calculated standard sample does not rely on physical standard samples, avoiding measurement errors introduced by the mismatch between the form of oxygen in traditional physical standard samples and the sample to be tested. During the calculation process, the built-in calculated standard sample can back-calculate the effective standard sample content based on the current matrix conditions of the sample to be tested, achieving adaptive matching and providing a stable reference for the quantitative analysis of trace oxygen. Furthermore, based on the signal intensity of oxygen and the signal intensity of major elements, a total correction factor is determined. Then, based on the total correction factor, the theoretical standard content of oxygen in the built-in calculated standard, and the signal intensity of oxygen, the oxygen content in the sample to be tested is determined. This avoids the limitations of relying on empirical correction or external standards for the detection of trace oxygen, achieving a matching solution between oxygen content and matrix composition, and effectively increasing the accuracy of oxygen content detection in samples during electron probe microscopy analysis.

[0079] To enable those skilled in the art to clearly understand the details and operations of the above embodiments of this application, and to demonstrate the significant improvement in the performance of the trace oxygen element detection method of the embodiments of this application, the above technical solutions are illustrated below through multiple embodiments.

[0080] Example 1 A titanium alloy metal sample 1 is provided as the test sample, and it is inlaid and mechanically polished until the test sample shows a mirror surface. The sample area to be measured was placed in the center of the argon ion beam polishing area. The polishing voltage was set to 5 kV, the ion beam incident angle to 3°, the sample stage rotation speed to 3 rpm, and the polishing time to 10 min. The accelerating voltage for EMPA testing was 20 kV, the beam current was 20 nA, the beam spot diameter was 1 μm, the peak position testing time for each element was 10 s, and the testing time for the left and right backgrounds was 5 s each. The major elements tested were Ti (PETJ), Al (TAP), V (LIFH), and O (LDE1H). The oxygen element was selected from the EPPA built-in calculation standard and the PRZ quantitative calibration method was used.

[0081] Comparative Example 1 A titanium alloy metal sample 1 is provided as the test sample, and it is inlaid and mechanically polished until the test sample shows a mirror surface. The accelerating voltage for EMPA testing was 20 kV, the beam current was 20 nA, the beam spot diameter was 1 μm, the peak position testing time for each element was 10 s, and the testing time for the left and right backgrounds was 5 s each. The major elements tested were Ti (PETJ), Al (TAP), V (LIFH), and O (LDE1H). The oxygen element was selected from the EPPA built-in calculation standard and the PRZ quantitative calibration method was used.

[0082] Example 2 A titanium alloy metal sample 2 is provided as the test sample, and it is inlaid and mechanically polished until the test sample shows a mirror surface; The sample area to be measured was placed in the center of the argon ion beam polishing area. The polishing voltage was set to 5 kV, the ion beam incident angle to 3°, the sample stage rotation speed to 3 rpm, and the polishing time to 10 min. The accelerating voltage for EMPA testing was 20 kV, the beam current was 20 nA, the beam spot diameter was 1 μm, the peak position testing time for each element was 10 s, and the testing time for the left and right backgrounds was 5 s each. The major elements tested were Ti (PETJ), Al (TAP), V (LIFH), and O (LDE1H). The oxygen element was selected from the EPPA built-in calculation standard and the PRZ quantitative calibration method was used.

[0083] Comparative Example 2 A titanium alloy metal sample 2 is provided as the test sample, and it is inlaid and mechanically polished until the test sample shows a mirror surface; The sample area to be measured was placed in the center of the argon ion beam polishing area. The polishing voltage was set to 5 kV, the ion beam incident angle to 3°, the sample stage rotation speed to 3 rpm, and the polishing time to 10 min. The accelerating voltage for EMPA testing was 20 kV, the beam current was 20 nA, the beam spot diameter was 1 μm, the peak position testing time for each element was 10 s, and the testing time for each of the left and right backgrounds was 5 s. The element tested was O (LDE1H), and the oxygen element was selected from the EPPA built-in calculation standard. The PRZ quantitative calibration method was used.

[0084] Taking oxygen as an example, in the oxygen content testing process of the above embodiments and comparative examples, the electron probe analyzer is fitted according to the database before leaving the factory and has built-in pre-set parameters. During the test, the signal intensity corresponding to the oxygen element signal peak, the energy spectrum correction coefficients of oxygen element, and the final output of the tested oxygen element content can be obtained. Furthermore, the oxygen element content can be derived by reverse calculation using the formula mentioned above. The detailed results are shown in Table 1 below.

[0085] Table 1. Oxygen element test data for the examples and comparative examples.

[0086]

[0087] The calculation process for other elements can be referenced above to obtain the content results for oxygen.

[0088] The test results of Example 1 and Comparative Example 1 are shown in Table 2.

[0089] Table 2. EMPA test results of metal sample 1.

[0090]

[0091] Table 2 shows that the data in Example 1 is closer to the true oxygen content in titanium alloy sample 1. In Comparative Example 1, the surface O contamination was not removed by ion beam polishing, resulting in a higher content.

[0092] The test results of Example 2 and Comparative Example 2 are shown in Table 3.

[0093] Table 3. EMPA test results of metal sample 2.

[0094]

[0095] Table 3 shows that, compared to Example 2, Comparative Example 2 only detected oxygen in the sample, and the failure to detect major elements resulted in a lower oxygen content.

[0096] The above are merely preferred embodiments of this application and do not limit the patent scope of this application. Various modifications and variations can be made to this application by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of this application should be included within the patent protection scope of this application.

Claims

1. A method for detecting trace oxygen elements based on an electron probe microanalyzer, characterized in that, The method for detecting trace oxygen elements includes: The sample to be tested is placed in an electron probe microanalyzer to obtain the signal intensity of oxygen and the signal intensity of major elements in the sample. Obtain the theoretical standard content of oxygen in the standard sample calculated by the built-in calculation function of the electron probe microanalyzer; The total correction factor is determined based on the signal intensity of the oxygen element and the signal intensity of the major elements. The oxygen content in the sample to be tested is determined based on the total correction factor, the theoretical standard content of oxygen in the built-in calculated standard sample, and the signal intensity of oxygen.

2. The method for detecting trace oxygen elements based on an electron probe microanalyzer as described in claim 1, characterized in that, The step of determining the total correction factor based on the signal intensity of oxygen and the signal intensity of the major elements includes: Based on the signal intensity of oxygen and the signal intensity of major elements, the atomic number correction coefficient, absorption correction coefficient and light element correction coefficient of the sample to be tested are determined, wherein the absorption correction coefficient is determined based on the integral of the depth distribution function of each element in the sample to be tested; The total correction factor is calculated based on the atomic number correction factor, the absorption correction factor, and the light element correction factor.

3. The method for detecting trace oxygen elements based on an electron probe microanalyzer as described in claim 1, characterized in that, Before the step of placing the sample to be tested in an electron probe microanalyzer to obtain the signal intensity of oxygen and the signal intensity of major elements in the sample, the method further includes: The sample to be tested was subjected to ion polishing.

4. The method for detecting trace oxygen elements based on an electron probe microanalyzer as described in claim 3, characterized in that, The voltage for ion polishing is 4 kV to 8 kV, the ion beam incident angle is 2° to 5°, the sample stage rotation speed is 3 rpm to 6 rpm, and the polishing time is 10 min to 20 min.

5. The method for detecting trace oxygen elements based on an electron probe microanalyzer as described in claim 3, characterized in that, The ion source for the ion polishing includes an argon ion beam.

6. The method for detecting trace oxygen elements based on an electron probe microanalyzer as described in claim 3, characterized in that, The surface roughness Ra of the sample to be tested after ion polishing is ≤ 100 nm.

7. The method for detecting trace oxygen elements based on an electron probe microanalyzer as described in claim 3, characterized in that, The sample to be tested, after ion polishing, was transferred to the electron probe microanalyzer for testing within 3 minutes. Alternatively, the sample to be tested, after ion polishing, can be placed in a vacuum of less than or equal to 1 x 10⁻⁶. -3 Saved in the environment of Pa.

8. The method for detecting trace oxygen elements based on an electron probe microanalyzer as described in claim 1, characterized in that, The accelerating voltage of the electron probe microanalyzer is 15 kV~20 kV, the beam current is 20 nA~100 nA, and the peak position testing time for oxygen is 10s~20s.

9. The method for detecting trace oxygen elements based on an electron probe microanalyzer as described in claim 1, characterized in that, The sample to be tested includes at least one of powder, bulk, and film. And / or, the resistivity of the sample to be tested is less than 100 Ω·cm; And / or, the oxygen content in the sample to be tested is greater than or equal to 100 ppm.

10. The method for detecting trace oxygen elements based on an electron probe microanalyzer as described in claim 1, characterized in that, The principal elements include: The element present in the sample to be tested at a concentration greater than or equal to 20%; Elements with atomic number Z ≤ 17.

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