阅读说明：本技术 基于单色x射线衍射的布拉格角测量方法 (Bragg angle measuring method based on monochromatic X-ray diffraction ) 是由 陈凯 寇嘉伟 朱文欣 沈昊 于 2019-09-19 设计创作，主要内容包括：本发明公开了一种基于单色X射线衍射的布拉格角测量方法,方法包括以下步骤：在待测样品上放置晶体粉末或者在待测样品旁边放置晶体粉末；移动X射线光源、线探测器和晶体粉末的相对位置,使得线探测器上能够同时出现n个来自于晶体粉末的衍射峰并测量其在线探测器上的坐标位置,并使得仅移动样品台便可测到待测布拉格角的衍射峰,构造方程组,求解方程组,得t<Sub>1</Sub>,t<Sub>2</Sub>,t<Sub>3</Sub>和t<Sub>4</Sub>的值；当晶体粉末涂覆于待测样品表面,直接获得待测布拉格角的衍射峰在线探测器上的坐标位置y,当晶体粉末置于样品旁边,通过移动待测样品至晶体粉末表面X射线照射点后,测量待测布拉格角的衍射峰在线探测器上的坐标位置y。(The invention discloses a Bragg angle measuring method based on monochromatic X-ray diffraction, which comprises the following steps: placing crystal powder on a sample to be detected or placing crystal powder beside the sample to be detected; moving the relative positions of the X-ray light source, the line detector and the crystal powder to enable n diffraction peaks from the crystal powder to appear on the line detector at the same time and measuring the coordinate position of the line detector, and enabling the diffraction peaks of the Bragg angle to be measured only by moving the sample stage, constructing an equation set, and solving the equation set to obtain t 1 ，t 2 ，t 3 And t 4 A value of (d); when the crystal powder is coated on the surface of a sample to be measured, the coordinate position y of the diffraction peak of the Bragg angle to be measured on the on-line detector is directly obtained, and when the crystal powder is arranged beside the sample, the sample to be measured is moved to the crystalAnd after the X-ray on the surface of the powder irradiates a point, measuring the coordinate position y of the diffraction peak of the Bragg angle to be measured on the on-line detector.)

1. A method of bragg angle measurement based on monochromatic X-ray diffraction, the method comprising the steps of:

in a first step (S1), placing crystal powder on or beside a sample to be tested;

in the second step (S2), the relative positions of the X-ray source, the line detector and the crystal powder are moved so that n diffraction peaks from the crystal powder appear on the line detector at the same time and the coordinate position of the line detector is measured, the diffraction peak of the bragg angle to be measured is measured,

a third step (S3) of constructing a system of equations:

，

wherein the content of the first and second substances,

i＝1……(n-1)，j＝(i+1)……n，y_idenotes the coordinate position of the ith diffraction peak from the crystal powder on the X-ray detector, and ki denotes the ith diffraction peak from the crystal powderSolving equation set to obtain t₁，t₂，t₃And t₄A value of (d);

a fourth step (S4) of directly obtaining the coordinate position y of the diffraction peak of the Bragg angle to be detected on the on-line detector when the crystal powder is coated on the surface of the sample to be detected, and measuring the coordinate position y of the diffraction peak of the Bragg angle to be detected on the on-line detector after the crystal powder is arranged beside the sample and the sample to be detected is moved to the X-ray irradiation point on the surface of the crystal powder;

a fifth step (S5) of obtaining a bragg angle 2 θ from the coordinate position y of the diffraction peak on the line detector, the bragg angle 2 θ being:

2. the method as claimed in claim 1, wherein, preferably, in the third step (S3), a spatial rectangular coordinate system is established in which the line detector is placed along the positive half axis of the y-axis with one end at the origin of the coordinate system with the normal direction of the surface being the positive direction of the z-axis, the X-ray irradiation point on the surface of the crystal powder is located at the coordinate of (a b c), the vector of the direction of the incident X-ray is (uv) and the vector is the unit vector, and the equation set in which the vector of the direction of the incident X-ray is (uv) is

3. The method of claim 1, wherein the crystalline powder comprises alumina powder, silicon powder, calcium carbonate powder, and/or lithium lanthanum zirconium oxide powder.

4. The method of claim 1, wherein in the first step (S1), the crystal powder is formed into a solution, emulsion or suspension, sprayed on the surface of the sample to be tested, and finally dried.

5. The method of claim 1, wherein in the first step (S1), the crystal powder is sprayed on the surface of the sample to be tested by an air flow or the crystal powder is adhered to the surface of the sample to be tested via an adhesion layer.

6. The method of claim 1, wherein in a third step (S3), the system of equations is solved by measuring at least 4 diffraction peaks from the crystalline powder.

7. The method as claimed in claim 1, wherein in the fourth step (S4), the measured peak shape of the diffraction peak is fitted using a gaussian distribution whose center is the coordinate position of the diffraction peak on the line detector.

8. The method according to claim 1, wherein in the third step (S3), the sample to be tested is single crystal, oriented crystal or polycrystalline.

Technical Field

The invention belongs to the technical field of diffraction measurement, and particularly relates to a Bragg angle measurement method based on monochromatic X-ray diffraction.

Background

The X-ray diffraction/stress gauge is a material characterization device with simple principle and relatively simple design and manufacture, and is widely used in scientific research work and production practice, in particular to an X-ray stress gauge using a line detector, which is widely equipped by various research institutions and production units. Since it is designed to measure the residual stress of a general polycrystalline sample, it is not very accurate to measure the bragg angle of each X-ray diffraction peak of the material. However, due to the wide range of applications including single crystal materials, the need for measuring various new materials including single crystal materials using existing equipment is pressing. The conventional X-ray stress gauge using a line detector is capable of satisfying the requirements for measuring these new materials in terms of mechanical structure and X-ray optical structure, but its measurement principle different from that of polycrystalline materials requires high accuracy of bragg angle measurement. Taking the measurement of the residual stress of the single crystal nickel-based superalloy as an example, the traditional X-ray stress meter can realize the measurement of a plurality of single crystal diffraction peaks by matching with a multi-degree-of-freedom sample stage. Unlike polycrystalline materials, however, the residual stress of single crystal materials needs to be calculated by taking the bragg angle of the measured diffraction peak as raw data and fitting the data. This requires that all the measured bragg angles of the X-ray diffraction peaks are very accurate (the accuracy is at least 0.1 °), but for the X-ray stress gauge widely equipped at present, due to the constraints of factors such as mechanical control and X-ray detector position calibration, the measured bragg angles of the diffraction peaks far from the requirement of measuring the residual stress of the single crystal material.

The existing method for solving the problem is started from improving the mechanical control precision of the X-ray stress gauge, and the measurement of the diffraction peak Bragg angle is realized by improving the electromechanical control precision of each movable mechanism of the device. Various devices including single crystal X-ray diffractometers based on the principle are widely applied in the scientific research field, but the application of the related devices in production practice is greatly limited due to the high cost and the maintenance difficulty of the devices.

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 Bragg angle measurement method based on monochromatic X-ray diffraction, which obviously improves the measurement precision and the measurement convenience.

The invention aims to realize the following technical scheme, and provides a Bragg angle measuring method based on monochromatic X-ray diffraction, which comprises the following steps:

in a first step (S1), placing crystal powder on or beside a sample to be tested;

in the second step (S2), the relative positions of the X-ray source, the line detector and the crystal powder are moved so that n diffraction peaks from the crystal powder appear on the line detector at the same time and the coordinate position of the line detector is measured, the diffraction peak of the bragg angle to be measured is measured,

a third step (S3) of constructing a system of equations:

wherein i is 1 … … (n-1), j is (i +1) … … n, y_iThe coordinate position of the ith diffraction peak from the crystal powder on an X-ray detector is indicated, ki represents the cosine value of the theoretical Bragg angle of the ith diffraction peak from the crystal powder, and an equation system is solved to obtain t₁，t₂，t₃And t₄A value of (d);

a fourth step (S4) of directly obtaining the coordinate position y of the diffraction peak of the Bragg angle to be measured on the on-line detector when the crystal powder is coated on the surface of the sample to be measured, and measuring the coordinate position y of the diffraction peak of the Bragg angle to be measured on the on-line detector after the crystal powder is arranged beside the sample and the sample to be measured is moved to the X-ray irradiation point on the surface of the crystal powder before the movement;

a fifth step (S5) of obtaining a diffraction peakObtaining a Bragg angle 2 theta from a coordinate position y on the line detector, wherein the Bragg angle 2 theta is as follows:

in the method, in the third step (S3), a spatial rectangular coordinate system is established, wherein the line detector is placed along the positive half axis of the y axis, one end of the line detector is located at the origin of the coordinate system, the surface normal direction of the line detector is the positive direction of the z axis, the coordinates of the X-ray irradiation point on the surface of the crystal powder are (a b c), the vector of the incident X-ray direction is (u v w), and the vector is the unit vector, and the equation set is formed by

In the method, the crystal powder comprises alumina powder, silicon powder, calcium carbonate powder and/or lithium lanthanum zirconium oxygen powder.

In the method, in the first step (S1), the crystal powder is formed into a solution, an emulsion or a suspension, sprayed on the surface of the sample to be tested, and finally dried.

In the method, in the first step (S1), the crystal powder is sprayed on the surface of the sample to be tested through the airflow or the crystal powder is adhered to the surface of the sample to be tested through the adhesion layer.

In the method, at least 4 diffraction peaks from the crystal powder are measured in the third step (S3) to solve the equation set.

In the method, in the fourth step (S4), a gaussian distribution is used to fit the peak shape of the measured diffraction peak, and the center of the gaussian distribution is the coordinate position of the diffraction peak on the line detector.

In the method, in the third step (S3), the sample to be measured is a single crystal, an oriented crystal, or a polycrystal.

Compared with the prior art, the invention has the following advantages:

the invention overcomes the defects of the existing detection, provides a more efficient and lower-cost mode, is suitable for the assembly line detection of mass samples, does not need to repeatedly adjust the relative position of each part of the equipment, and can obviously improve the precision; the method can be used for the surface of a complex geometric sample, has great advantages for analyzing the complex geometric sample, accurately calibrates the single crystal sample by collecting signals for measurement using monochromatic light to represent the single crystal sample, and compared with the prior art, the method does not need to refit the traditional X-ray stress meter and has no new mechanical mechanism, the whole calibration process is completed by calculation, and the like, and has the characteristics of low cost, simple operation and the like.

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 step diagram of a Bragg angle measurement method based on monochromatic X-ray diffraction according to one embodiment of the present invention;

fig. 2 is a schematic layout diagram for implementing a bragg angle measurement method based on monochromatic X-ray diffraction 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 fig. 1 to 2. 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 2, a bragg angle measurement method based on monochromatic X-ray diffraction, the method comprising the steps of:

in a first step (S1), placing crystal powder on or beside a sample to be tested;

in the second step (S2), the relative positions of the X-ray source, the line detector and the crystal powder are moved so that n diffraction peaks from the crystal powder appear on the line detector at the same time and the coordinate position of the line detector is measured, the diffraction peak of the bragg angle to be measured is measured,

a third step (S3) of constructing a system of equations:

wherein the content of the first and second substances,

i＝1……(n-1)，j＝(i+1)……n，y_ithe coordinate position of the ith diffraction peak from the crystal powder on an X-ray detector is indicated, ki represents the cosine value of the theoretical Bragg angle of the ith diffraction peak from the crystal powder, and an equation system is solved to obtain t₁，t₂，t₃And t₄A value of (d);

a fourth step (S4) of directly obtaining the coordinate position y of the diffraction peak of the Bragg angle to be measured on the on-line detector when the crystal powder is coated on the surface of the sample to be measured, and measuring the coordinate position y of the diffraction peak of the Bragg angle to be measured on the on-line detector after the crystal powder is arranged beside the sample and the sample to be measured is moved to the X-ray irradiation point on the surface of the crystal powder before the movement;

a fifth step (S5) of obtaining a bragg angle 2 θ from the coordinate position y of the diffraction peak on the line detector, the bragg angle 2 θ being:

in order to make the description of the present invention clearer, the specific implementation steps and technical details of the present invention are specifically described by using pure nickel as a test sample, a diffraction peak of a bragg angle to be measured at a (022) peak position thereof, LLZO powder as crystal powder, an X-ray tube using Cr as a target material as an X-ray light source, and a line detector capable of measuring the bragg angle range of 40 ° as an X-ray detector.

In this embodiment, the sample placement position, the X-ray light source position, the line detector position with 256 pixels, and the established three-dimensional rectangular coordinate system are shown in fig. 2.

The first step (S1) of coating the LLZO crystal powder on the surface of the pure nickel sample to be tested, moving the relative positions of the X-ray source, the X-ray line detector and the LLZO powder crystal so that the bragg angle corresponding to the position of the center point of the X-ray line detector is 140.3 °, even if 6 diffraction peaks from the LLZO crystal powder simultaneously appear on the detector. And performing Gaussian fitting on the peak shape of each diffraction peak, and measuring the coordinate positions of each diffraction peak on an X-ray detector to be 15.98, 44.33, 102.66, 153.62, 173.06 and 194.60 respectively, wherein the Bragg angles of each diffraction peak on theory are 122.22 degrees, 126.57 degrees, 136.13 degrees, 144.57 degrees, 147.79 degrees and 151.33 degrees respectively. At this time, the (022) diffraction peak of the pure nickel sample to be measured can be measured without moving the relative position of the detector and the X-ray source.

A second step (S2) of constructing a system of equations

i＝1……(n-1)，j＝(i+1)……n，

Wherein the parameter y_iValue of (a), respectively y₁＝15.98，y₂＝44.33，y₃＝102.66，y₄＝153.62，y₅＝173.06，y₆＝194.60。k_iCosine values of theoretical Bragg angle representing ith diffraction peak from crystal powder, and k is₁＝-0.5329，k₂＝-0.5962，k₃＝-0.7206，k₄＝-0.8151，k₅＝-0.8462，k₆-0.8771. Solving the system of equations, t₁，t₂，t₃，t₄Are 281.45, 2.4044, 300.56, 320510, respectively.

And a third step (S3) of measuring the position coordinate y of the (022) diffraction peak of the pure nickel sample to be measured on the line detector to be 94.01.

In the fourth step (S4), the coordinate position of the measured diffraction peak on the X-ray detector is set to "y" 94.01.

The value of the bragg angle 2 θ was calculated to be 134.67 ° according to the following formula.

In a preferred embodiment of the method, in the third step (S3), a spatial rectangular coordinate system is established, wherein the line detector is placed along the positive half axis of the y-axis and one end is located at the origin of the coordinate system, the surface normal direction is the positive direction of the z-axis, the X-ray irradiation point on the surface of the crystal powder is located at the coordinate (a b c), the incident X-ray direction vector is (uv w) and the vector is the unit vector, and the equation set includes

In a preferred embodiment of the method, the crystalline powder comprises alumina powder, silicon powder, calcium carbonate powder and/or lithium lanthanum zirconium oxide powder.

In a preferred embodiment of the method, in the first step (S1), the crystal powder is formed into a solution, an emulsion or a suspension, sprayed on the surface of the sample to be tested, and finally dried.

In a preferred embodiment of the method, in the first step (S1), the crystal powder is sprayed on the surface of the sample to be tested through the airflow or the crystal powder is adhered to the surface of the sample to be tested through the adhesion layer.

In a preferred embodiment of the method, in the third step (S3), the system of equations is solved by measuring at least 4 diffraction peaks from the crystalline powder.

In a preferred embodiment of the method, in the fourth step (S4), the measured peak shape of the diffraction peak is fitted with a gaussian distribution, and the center of the gaussian distribution is the coordinate position of the diffraction peak on the line detector.

In a preferred embodiment of the method, in the third step (S3), the sample to be tested is a single crystal, an oriented crystal, or a polycrystal.

In a preferred embodiment, the crystal powder is selected from alumina powder and silicon powder.

In a preferred embodiment, the crystal powder is placed by spraying the crystal powder on the surface of the sample to be tested through a system of forming solution, emulsion and suspension. After the liquid system is sprayed on the surface of a sample, crystal powder is placed on the surface of the sample to be detected through drying. The person skilled in the art can choose to form solutions, emulsions or suspension systems.

In a preferred embodiment, the crystal powder is placed by spraying the crystal powder on the surface of the sample to be tested through an air flow. Through the air current spraying, can realize placing crystal powder on the sample surface that awaits measuring.

In a preferred embodiment, the crystal powder is placed by adhering the crystal powder to an adhesive tape, and adhering the adhesive tape to the surface of the sample to be tested.

In summary, the invention can achieve the purpose of improving the experimental precision by placing the calibration crystal powder on the surface of the sample to be tested and collecting the diffraction signals of the sample to be tested and the crystal powder.

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.