阅读说明：本技术 基于x射线能量扫描的两相错配度的测量方法 (Method for measuring two-phase mismatching degree based on X-ray energy scanning ) 是由 陈凯 寇嘉伟 沈昊 朱文欣 于 2019-09-19 设计创作，主要内容包括：本发明公开了一种基于X射线能量扫描的两相错配度的测量方法,方法包括以下步骤：用发射连续谱X射线照射样品表面,X射线面探测器接收来自样品表面的共有n个衍射峰的劳厄衍射图谱,标定劳厄衍射图谱得到其中第i个衍射峰的米勒指数,计算劳厄衍射图谱上各衍射峰对应的X射线能量,以步长ΔE<Sub>0</Sub>在能量范围E<Sub>0</Sub>-E<Sub>t</Sub>至E<Sub>0</Sub>+E<Sub>t</Sub>内扫描,测量m个不同的能量E<Sub>j</Sub>,在所有衍射向量长度|k<Sub>j,j′</Sub>|中找到所有值在区间[d<Sub>l</Sub>,d<Sub>l</Sub>+Δd)内的衍射向量长度并求这些衍射向量长度对应的像素点上的强度的平均值I<Sub>aver,l</Sub>,在平面直角坐标系中绘制r个点<Image he="229" wi="695" file="DDA0002206795070000011.GIF" imgContent="drawing" imgFormat="GIF" orientation="portrait" inline="no"></Image>使用双峰拟合函数拟合各点得到分别来自样品中两相的峰的峰中心d<Sub>1</Sub>和d<Sub>2</Sub>；计算样品两相的第一相和第二相之间的错配度θ量。(The invention discloses a method for measuring two-phase mismatching degree based on X-ray energy scanning, which comprises the following steps: irradiating the surface of a sample by using emitted continuous spectrum X-rays, receiving a Laue diffraction pattern with n diffraction peaks from the surface of the sample by using an X-ray surface detector, calibrating the Laue diffraction pattern to obtain the Miller index of the ith diffraction peak, calculating the X-ray energy corresponding to each diffraction peak on the Laue diffraction pattern, and calculating the step length delta E 0 In the energy range E 0 ‑E t To E 0 +E t Internal scanning, measuring m different energies E j At all diffraction vector lengths | k j,j′ Find all values in the interval [ d ] l ,d l The lengths of the diffraction vectors within + Δ d) and the average value I of the intensities at the pixels corresponding to these lengths of the diffraction vectors aver,l Drawing r points in a rectangular plane coordinate system Fitting using a bimodal fitting functionEach point gives the peak center d of the peak from two phases in the sample respectively 1 And d 2 (ii) a The amount of mismatch θ between the first and second phases of the two phases of the sample was calculated.)

1. A method for measuring two-phase mismatch based on X-ray energy scanning, the method comprising the steps of:

in a first step (S1), emitting continuum X-rays to irradiate a sample surface, receiving a Laue diffraction pattern of a total of n diffraction peaks from the sample by an X-ray surface detector, and calibrating the Laue diffraction pattern;

in a second step (S2), the X-ray energies corresponding to the diffraction peaks on the Laue diffraction pattern are calculated according to the theoretical lattice parameters of the sample, and the X-ray energy E corresponding to one of the diffraction peaks is selected₀A monochromator is arranged, and the step length delta E is adjusted by the monochromator arranged on the X-ray incidence light path₀In the energy range E₀-E_tTo E₀+E_tInternal scanning, using said X-ray surface detector to receive m different energies E_jDiffraction peak P of_jSaid diffraction peak P_jHas m at the top_jEach pixel point X_j,j′The intensity of X-ray at each pixel is I_j,j′Wherein j is 1,2,3 … … m, j' is 1,2,3 … … m_j；

In the third step (S3), all diffraction peaks P are calculated_jAll the above pixel points X_j,j′Corresponding diffraction vector length | k_j,j′Wherein the vector from the X-ray source to the X-ray irradiation point on the sample surface is the incident vector

in the fourth step (S4), the curve sampling rate r is set to the interval [ min { | k)_j,j′|},max{|k_j,j′|}]Is divided into r sections with equal distance, each section has the length delta d, and the starting point of the l section is d_lWhere l is 1,2,3 … … r, for the l-th segment, at all diffraction vector lengths | k_j,j′Find all values in the interval [ d ]_l,d_lThe lengths of the diffraction vectors within + Δ d) and the average value I of the intensities at the pixels corresponding to these lengths of the diffraction vectors_aver,lWhere l is 1,2,3 … … r;

in the fifth step (S5), r points are plotted in a planar rectangular coordinate system

In the sixth step (S6), the degree of mismatch theta between the first phase and the second phase of the two phases of the sample is calculated,

2. the method of claim 1, wherein preferably the sample comprises a coherent or semi-coherent biphasic structure.

3. The method according to claim 1, wherein in the first step (S1), the continuous spectrum X-ray emitting light source is a target Bremsstrahlung X-ray emitting light source or a synchrotron-radiation X-ray emitting light source.

4. The method of claim 1, wherein in the second step (S2), the scanning step size and the scanning range are adjusted based on the monochromator parameter and the property of the measured material, the step size Δ Ε₀Is 2eV, scan range E_tIs 25 eV.

5. The method of claim 1, wherein in the fourth step (S4), the curve sampling rate r is adjusted based on a step size of the energy scan and a resolution of the X-ray area detector.

6. The method of claim 1, wherein in the fourth step (S4), the curve sampling rate r is 200.

7. The method of claim 1, wherein the laue diffraction pattern has at least 4 diffraction peaks.

8. The method according to claim 1, wherein in the fourth step (S4), the intensity of the X-ray received by the pixel is the number of X-ray photons received by the pixel within the exposure time, the number of detected photons at the pixel, or the current value corresponding to the pixel, according to the X-ray area detector used.

9. The method according to claim 1, wherein in the fifth step (S5), the fitting of the bimodal fitting is performed using a gaussian distribution function, a lorentz distribution function or a Voigt distribution function.

Technical Field

The invention belongs to the technical field of material coherent or semi-coherent two-phase mismatching degree measurement, and particularly relates to a method for measuring two-phase mismatching degree based on X-ray energy scanning.

Background

In view of the excellent performances of various coherent or semi-coherent two-phase structure materials in ductility and toughness and high-temperature durability, coherent or semi-coherent two-phase structures are mostly adopted in the design of modern various alloys. For a coherent or semi-coherent dual-phase structure, the mismatching degree between the two phases has a remarkable influence on the mechanical property of the material, and different mechanical property design indexes can be realized by regulating and controlling the mismatching degree between the two phases during alloy design. The feature of coherent or semi-coherent biphase determines that the degree of mismatch is generally very small. Taking the third generation precipitation strengthening nickel-based high temperature alloy as an example, the mismatching degree is generally between one thousandth and one ten thousandth at normal temperature, and the mismatching degree is usually less than one ten thousandth at the working temperature.

The existing methods for measuring the mismatching degree include a monochromatic X-ray diffraction method, a convergent electron beam diffraction method and the like. For monochromatic X-ray diffraction, the sample needs to be continuously rotated in two dimensions by extremely small steps during measurement, and the time is long. The convergent electron beam diffraction method needs to be implemented in a transmission electron microscope, has high requirements on samples, and has the tissue structure and the stress state between two phases are different from that of a block material due to the extremely low thickness of the sample which is generally less than 100nm, so that the measurement result still needs to be corrected by means of finite element simulation and the like.

The above information disclosed in this background section is only for enhancement of understanding of the background of the invention and therefore it may contain information that does not form the prior art that is already known in this country to a person of ordinary skill in the art.

Disclosure of Invention

Aiming at the problems in the prior art, the invention provides a method for measuring the two-phase mismatch degree based on X-ray energy scanning, which simplifies the measurement requirement and realizes high-speed high-spatial resolution and high-precision mismatch degree measurement. Aiming at the currently used precipitation strengthening nickel-based superalloy, the method can measure the mismatching degree of the precipitation strengthening nickel-based superalloy under various temperature conditions. The method has simple flow and small data processing calculation amount.

The invention aims to realize the purpose through the following technical scheme, and the method for measuring the two-phase mismatching degree based on X-ray energy scanning comprises the following steps of:

in the first step, continuous spectrum X-ray is emitted to irradiate the surface of a sample, an X-ray surface detector receives a Laue diffraction pattern of n diffraction peaks from the sample, and the Laue diffraction pattern is calibrated to obtain the Miller index [ h ] of the ith diffraction peak_i k_i l_i]Wherein i is 1,2,3 … … n;

in the second step, according to the theoretical lattice parameter of the sample, calculating the X-ray energy corresponding to each diffraction peak on the Laue diffraction map, and selecting the X-ray energy E corresponding to one diffraction peak₀The Miller index of which is [ h ]_s k_s l_s]A monochromator is arranged, and the step length delta E is adjusted by the monochromator arranged on the X-ray incidence light path₀In the energy range E₀-E_tTo E₀+E_tInternal scanning, using said X-ray surface detector to receive m different energies E_jDiffraction peak P of_jAnd the diffraction peak P_jHas m at the top_jEach pixel point X_j,j′The intensity of X-ray at each pixel is I_j,j′Wherein j is 1,2,3 … … m, j' is 1,2,3 … … m_j；

In the third step, all diffraction peaks P are calculated_jAll the above pixel points X_j,j′Corresponding diffraction vector length | k_j,j′Wherein the vector from the X-ray source to the X-ray irradiation point on the sample surface is the incident vectorSample surface X-ray irradiation point to pixel point X on X-ray surface detector_j,j′The vector of (a) is an outgoing vector

Pixel point X_j,j′Corresponding diffraction vector length of

Wherein h isIs Planck constant, c is speed of light in vacuum;

in the fourth step, the curve sampling rate r is the interval [ min { | k_j,j′|},max{|k_j,j′|}]Is divided into r sections with equal distance, each section has the length delta d, and the starting point of the l section is d_lWhere l is 1,2,3 … … r, for the l-th segment, at all diffraction vector lengths | k_j,j′Find all values in the interval [ d ]_l,d_lThe lengths of the diffraction vectors within + Δ d) and the average value I of the intensities at the pixels corresponding to these lengths of the diffraction vectors_aver,lWhere l is 1,2,3 … … r;

in the fifth step, r points are drawn in a plane rectangular coordinate system

Where l is 1,2,3 … … r, peak centers d of peaks from two phases in the sample, respectively, are obtained by fitting each point using a bimodal fitting function₁And d₂；

In the sixth step, the degree of mismatch theta between the first phase and the second phase of the two phases of the sample is calculated,

in the method, the sample comprises a coherent or semi-coherent biphasic structure.

In the method, in the first step, the light source emitting continuous spectrum X-rays may be a light source emitting bremsstrahlung X-rays or a synchrotron radiation X-ray light source using a target material.

In the method, in the second step, the scanning step length and the scanning range are adjusted based on the monochromator parameters and the properties of the measured material, and the general step length delta E₀Is 2eV, scan range E_tIs 25 eV.

In the method, in the fourth step, the curve sampling rate r is adjusted based on the step length of the energy scanning and the resolution of the X-ray surface detector.

In the fourth step of the method, the sampling rate r of the curve is 200.

In the method, the Laue diffraction pattern has at least 4 diffraction peaks.

In the method, in the fourth step, according to the difference of the used X-ray detectors, the intensity of the X-ray received by the pixel point is the number of X-ray photons received by the pixel point within the exposure time, the number of photoelectrons detected by the pixel point, or the current value corresponding to the pixel point.

In the fifth step of the method, fitting is carried out by adopting a Gaussian distribution function, a Lorentzian distribution function or a Voigt distribution function in a double-peak fitting mode.

Drawings

Various other advantages and benefits of the present invention will become apparent to those of ordinary skill in the art upon reading the following detailed description of the preferred embodiments. The drawings are only for purposes of illustrating the preferred embodiments and are not to be construed as limiting the invention. It is obvious that the drawings described below are only some embodiments of the invention, and that for a person skilled in the art, other drawings can be derived from them without inventive effort. Also, like parts are designated by like reference numerals throughout the drawings.

In the drawings:

FIG. 1 is a schematic diagram of the steps of a method for measuring two-phase mismatch based on X-ray energy scanning according to an embodiment of the present invention;

FIG. 2 is a schematic representation of a Laue diffraction pattern of a two-phase mismatch measurement method based on an X-ray energy scan according to one embodiment of the present invention;

FIG. 3 is a graphical representation of the calibration results of the Laue diffraction pattern of a two-phase mismatch measurement method based on an X-ray energy scan according to one embodiment of the present invention;

FIG. 4 is a graph showing points of bimodal fitting and bimodal fitting results based on a method of measuring two-phase mismatch in an X-ray energy scan, according to an embodiment of the present invention.

The invention is further explained below with reference to the figures and examples.

Detailed Description

Specific embodiments of the present invention will be described in more detail below with reference to the accompanying drawings. While specific embodiments of the invention are shown in the drawings, it should be understood that the invention may be embodied in various forms and should not be construed as limited to the embodiments set forth herein. Rather, these embodiments are provided so that this disclosure will be thorough and complete, and will fully convey the scope of the invention to those skilled in the art.

It should be noted that certain terms are used throughout the description and claims to refer to particular components. As one skilled in the art will appreciate, various names may be used to refer to a component. This specification and claims do not intend to distinguish between components that differ in name but not function. In the following description and in the claims, the terms "include" and "comprise" are used in an open-ended fashion, and thus should be interpreted to mean "include, but not limited to. The description which follows is a preferred embodiment of the invention, but is made for the purpose of illustrating the general principles of the invention and not for the purpose of limiting the scope of the invention. The scope of the present invention is defined by the appended claims.

For the purpose of facilitating understanding of the embodiments of the present invention, the following description will be made by taking specific embodiments as examples with reference to the accompanying drawings, and the drawings are not to be construed as limiting the embodiments of the present invention.

For better understanding, as shown in fig. 1 to 4, a method for measuring two-phase mismatch based on X-ray energy scanning, the method comprising the steps of:

in a first step (S1), a sample is irradiated using an emitting continuum X-ray source, an X-ray area detector receives a Laue diffraction pattern having a total of n diffraction peaks from the sample surface, and the Laue diffraction pattern is calibrated to obtain the Miller index [ h ] of the ith diffraction peak therein_i k_i l_i]Wherein i is 1,2,3 … … n;

in a second step (S2), the X-ray energy corresponding to each diffraction peak on the Laue diffraction pattern is calculated according to the theoretical lattice parameter of the sample, and one of the derivatives is selectedEnergy E of X-ray corresponding to peak₀The Miller index of which is [ h ]_s k_s l_s]A monochromator is arranged, and the step length delta E is adjusted by the monochromator arranged on the X-ray incidence light path₀In the energy range E₀-E_tTo E₀+E_tInternal scanning, using said X-ray surface detector to receive m different energies E_jDiffraction peak P of_jAnd the diffraction peak P_jHas m at the top_jEach pixel point X_j,j′The intensity of X-ray at each pixel is I_j,j′Wherein j is 1,2,3 … … m, j' is 1,2,3 … … m_j；

In the third step (S3), all diffraction peaks P are calculated_jAll the above pixel points X_j,j′Corresponding diffraction vector length | k_j,j' |, wherein the vector defining the X-ray source to the X-ray irradiation point on the sample surface is the incident vector

Sample surface X-ray irradiation point to pixel point X on X-ray surface detector_j,j′The vector of (a) is an outgoing vector

Pixel point X_j,j′Corresponding diffraction vector length of

Wherein h is the Planck constant, and c is the vacuum light velocity;

in the fourth step (S4), a curve sampling rate r is defined, and the interval [ min { | k)_j,j′|},max{|k_j,j′|}]Is divided into r sections with equal distance, each section has the length delta d, and the starting point of the l section is d_lWhere l is 1,2,3 … … r, for the l-th segment, at all diffraction vector lengths | k_j,j′Find all values in the interval [ d ]_l,d_lThe lengths of the diffraction vectors within + Δ d) and the average value I of the intensities at the pixels corresponding to these lengths of the diffraction vectors_aver,lWhere l is 1,2,3 … … r;

in the fifth step (S5), in the planeDrawing r points in rectangular coordinate system

Where l is 1,2,3 … … r, peak centers d of peaks from two phases in the sample, respectively, are obtained by fitting each point using a bimodal fitting function₁And d₂；

In the sixth step (S6), the degree of mismatch theta between the first phase and the second phase of the two phases of the sample is calculated,

to further understand the present invention, in one embodiment, and to make the description of the invention clearer, a nickel-base superalloy known by the reference DD407 was used as the test sample, a synchrotron white light source was used as the X-ray source, a monochromator made of four pieces of surface (111) crystal plane single crystal silicon, and an X-ray area detector.

The specific steps of the measurement method in this specific embodiment are as follows:

the method comprises the following steps: the sample surface was irradiated with an X-ray source and the laue diffraction pattern from the sample was received with an X-ray area detector, the received pattern being shown in figure 2. The total number of diffraction peaks in the spectrum is 11. The Laue diffraction patterns were calibrated using known methods and the results are shown in FIG. 3.

Step two: the lattice parameters of the two coherent phases of the nickel-base superalloy with the designation DD407 are approximately 0.3588, 0.3588, 0.3588, 90 ° α, 90 ° β, and 90 ° γ. And calculating the X-ray energy corresponding to each diffraction peak by using a Bragg equation according to the position of each diffraction peak on the Laue diffraction spectrum. Selecting the optimum working range of the monochromator

The X-ray energy corresponding to the peak is E₀16480 eV. The X-ray is put into the incident light path, and scanning is carried out in a step size of 2eV within the energy range of 16340eV and 16620eV by adjusting a monochromator, and 141 different energies E are measured_j. Using the X-ray detectorDiffraction peak P at different energies_jAnd the diffraction peak has m in total_jEach pixel point is X_j,j′Is represented by I_j,j′X-ray intensities at each pixel point are shown, where j is 1,2,3 … … 141, and j is 1,2,3 … … m_j。

Step three: defining the vector of X-ray source to the X-ray irradiation point on the surface of the sample as incident vector and using unit vector

And (4) showing. Defining the X-ray irradiation point on the surface of the sample to the pixel point X on the X-ray surface detector_j,j′The vector of (a) is an outgoing vector and a unit vector is used

Calculating a pixel point X_j,j′Corresponding diffraction vector length | k_j,j′L. The method comprisesWhere h is the Planck constant and c is the vacuum speed of light.

Step four: the curve sampling rate r is defined as 190. The interval [ min { | k in this embodiment_j,j′|},max{|k_j,j′|}]Is [ min { | k)_j,j′|},max{|k_j,j′|}]The interval is divided into 190 equally spaced segments, each segment having a length of 0.0025nm^-1. The starting point of the l-th segment is defined as dl, where l is 1,2,3 … … 190. For the l-th segment, at all diffraction vector lengths | k_j,jFind all values in the interval [ d ]_l,d_lThe length of the diffraction vector within + Δ d) and the average of the intensities at the pixels corresponding to these lengths of the diffraction vector are calculated, I_aver,lHere, l is 1,2,3 … … 190.

Step five: will have 190 points in totalPlotted in a planar rectangular coordinate system, where l is 1,2,3 … … 190. It was fit bimodal using the Voigt distribution, the distribution of points and the fitted curve being shown in figure 4. ByAs a result of the fitting, the peak center of the peak derived from the two phases in the test sample was d₁＝19.9296nm^-1And d₂＝19.8574nm^-1。

Step six: using the formula

The degree of mismatch was calculated and found to be-3.6 x 10^-3。

In a preferred embodiment of said method, said sample comprises a coherent or semi-coherent biphasic structure.

In a preferred embodiment of the method, in the first step (S1), the continuous spectrum X-rays are emitted as a source of bremsstrahlung or synchrotron-radiation X-rays from the target material.

In a preferred embodiment of the method, in a second step (S2), the step size is adjusted based on the monochromator parameter, the step size Δ E₀Is 2eV, E_tIs 25 eV. The actual operation can be adjusted according to the performance of the monochromator used.

In a preferred embodiment of the method, in the fourth step (S4), the curve sampling rate r is adjusted based on the step size of the energy scan and the resolution of the X-ray area detector.

In a preferred embodiment of the method, in the fourth step (S4), the curve sampling rate r is 200.

In a preferred embodiment of the method, the laue diffraction pattern has at least 6 diffraction peaks.

In a preferred embodiment of the method, in the fourth step (S4), according to a difference of the used X-ray detectors, the intensity of the X-ray received by the pixel is the number of X-ray photons received by the pixel within the exposure time, the number of photoelectrons detected by the pixel, or the current value corresponding to the pixel. .

In a preferred embodiment of the method, in the fifth step (S5), the fitting is performed by using a gaussian distribution function, a lorentz distribution function, or a Voigt distribution function.

The invention is based on the X-ray micro-beam diffraction technology with the energy scanning function of the synchrotron radiation light source, and the white light micro-beam Laue diffraction and the energy scanning, and realizes the high-speed high-spatial resolution high-precision mismatch measurement. Aiming at the currently used precipitation strengthening nickel-based superalloy, the method can measure the mismatching degree of the precipitation strengthening nickel-based superalloy under various temperature conditions. The method has simple flow and small data processing calculation amount. Compared with the prior art, the method has stronger creativity.

Although the embodiments of the present invention have been described above with reference to the accompanying drawings, the present invention is not limited to the above-described embodiments and application fields, and the above-described embodiments are illustrative, instructive, and not restrictive. Those skilled in the art, having the benefit of this disclosure, may effect numerous modifications thereto without departing from the scope of the invention as defined by the appended claims.