JPH0675044B2 - X-ray cotsel diffraction image automatic analyzer - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Use) The present invention automatically drives a measurement sample in accordance with a digital image obtained by image-processing a scanning electron microscope image or a light microscope image of a crystal orientation measurement sample in a minute region to measure each measurement point. X-ray Cossel diffraction images are sequentially input to the image memory, image processing is performed, and then the crystallographic orientation of the minute area where the measurement sample is digitized is automatically analyzed, and a pole figure is created and a crystal orientation color map is created. It relates to a device for

(Conventional technology) As a method for measuring the crystal orientation of a minute region, a Cossel diffraction line analysis method using a scanning electron microscope image (hereinafter referred to as SEM image) is used instead of the conventional micro-laue method or etch pit method. It's starting. This method is a combination of a scanning electron microscope and a Kossel camera, as disclosed by the inventors in Japanese Patent Laid-Open No. 55-33660 and Japanese Utility Model Publication No. 57-47791. An electron beam for an electron microscope, which has been narrowed down to a few microns in diameter, is irradiated, and an image of a Kossel diffraction line generated by exciting atoms in a minute region is photographed by a Kossel camera.

However, because of the use of X-ray film, setting the film in the device, developing and fixing the film,
It took time and labor to analyze the film, and it was very difficult to obtain information on a wide range of textures.

In order to solve the above-mentioned drawbacks, the inventors of the present invention have disclosed JP-A-56-262
No. 48 discloses an X-ray Cossel diffraction image observation apparatus using an X-ray image intensifier. This device can replace the conventional X-ray film and convert the output of the X-ray image intensifier into digital data for display on a cathode ray tube. However,
The X-ray Cossel diffraction image obtained in this way cannot be used as it is as experimental data. In order to minimize the error in the analysis of the Cossel diffraction image and to save labor, automation of analysis is performed. Was essential.

Computer-aided image analysis methods have been developed since the early 1960s, and automatic measurement of the distance of a diffraction spot by the X-ray Laue method or electron beam diffraction method has been performed. It is considered that it is possible to automate the analysis of the orientation of the image of the Cossel diffraction line and the amount of distortion by connecting an image analysis device, and as a device capable of processing a large amount of data with high precision and in a short time, Japanese Patent Laid-Open No. 60-166.
By eliminating the above-mentioned drawbacks in No. 847 and automatically analyzing the orientation and distortion amount of the image of the Kossel diffraction line,
We proposed an X-ray Cossel diffraction pattern analyzer that can process a large amount of data with high accuracy and in a short time with few errors.

This X-ray Cossel diffraction image analyzer comprises an X-ray image intensifier, an image memory for storing its output, and a signal processing device for reading out the data stored in the image memory and performing signal processing. In the X-ray Cossel diffraction image observation device that makes it possible to observe the Cossel diffraction line as a digital image by processing the data obtained by projecting the Cossel diffraction line on the ear, the shortest distance from the origin on the screen on the Cossel diffraction line An image processing device that performs a process necessary to obtain a copy;
The image analysis device for obtaining the line width and curvature of the Cossel diffraction line at the shortest distance portion, the conversion device for obtaining the strain amount and crystal orientation from the obtained line width and curvature of the Cossel diffraction line, and the obtained strain amount and crystal orientation And a display device for displaying.

(Problems to be solved by the invention) However, in this X-ray Cossel diffraction image analyzer, (1) driving of each crystal grain to a measurement position is performed by an optical microscope or SE
Since it is performed manually according to the M image, the measurement cannot be fully automated. In addition, (2) the display that is analyzed and output from the digitized X-ray Cossel diffraction image only finds the (hkl) pole point by stereo projection arbitrarily extracted from the Kossel diffraction digital image, and this alone However, it cannot be said that the description of the crystal orientation is perfect.

In other words, the problems that must be solved in order to realize the final requirement of automatically measuring the crystal orientation of each crystal grain existing in a minute region and displaying the result clearly (for example, mapping of the metal structure). It is a point.

(Means for solving problems) In the 1980s, the image processing / analyzing device was introduced to the dedicated processor using a personal computer instead of a general-purpose computer as in the past, resulting in faster data processing, and at the site. Since it has become possible to compose software programs suitable for the above, it can be widely used in fields such as industry, communication, medical care, and commerce, and different types of input data can be processed in parallel with the increase in memory capacity. In addition to being able to process and analyze (multi-memory channel), a color image memory can be provided, and the result of processing and analysis can be displayed in color.

The inventors disclosed the X disclosed in the above-mentioned JP-A-56-26248.
Sequential automatic emission of electron beam by connecting image processor / autofocus / stage controller and color display device (CRT, printer, etc.) for image processing / analysis in which the above-mentioned multi-memory channel system is introduced to the line-COSSEL diffraction image observation device We have developed an automatic X-ray Cossel diffraction image analyzer that can perform irradiation, automatically create pole figures, and perform color mapping.

That is, the present invention relates to an X-ray image intensifier, an X-ray Kossel diffraction image observation apparatus including an image memory for storing the output thereof, and a signal processing apparatus for reading out the data stored in the image memory and performing signal processing, and the Kossel diffraction image observation apparatus. An image processing device for obtaining the shortest distance portion from the origin on the screen on the line, an image analysis device for obtaining the curvature of the Cossel diffraction line at the shortest distance portion, and a conversion device for obtaining the crystal orientation from the obtained curvature of the Cossel diffraction line, In an X-ray Cossel diffraction image analyzer comprising a display device for displaying the obtained crystal orientation, an optical microscope image detection device 3 for detecting the crystal structure of the sample, and an SEM image by the reflected electron beam scattered from the sample are detected. S
An EM image detection device 4, an input interface 5 for processing and converting the signals of these optical microscope image, SEM image and X-ray Cossel diffraction image, a grayscale image memory for storing image data, and binary data of grain boundaries. Image memory 6-1 comprising a binary memory for storing and a color memory for storing color image data
And the image processing / diffraction CPU6-2 for binarizing the X-ray Cossel diffraction image and crystal orientation analysis, and the control / editing dedicated CPU6-3 for starting and controlling the entire system by inputting crystal orientation measurement coordinates. The image processor 6 and the output signal of the control / editing dedicated CPU 6-3 move the sample position in the X-ray Cossel diffraction image observation apparatus 1, and
An X-ray cossel comprising a stage drive / electron gun start / stop device 9 for automatically starting and stopping the electron gun, a color display device 8 for displaying a color image, and a plotter for making a pole figure. This is an automatic diffraction image analyzer.

Hereinafter, the configuration of the present invention will be described in more detail with reference to the drawings.

FIG. 1 is an example of a block diagram of the X-ray Cossel diffraction image observation apparatus of the present invention. In FIG. 1, the electron beam emitted from the electron gun 1-1 inside the main body of the X-ray Cossel diffraction image observation apparatus 1 is , Convergent lens 1-2, objective lens 1-
Focus on a microscopic area on the sample 1-4 through 3. The sample 1-4 is excited by the irradiation of this electron beam and emits a characteristic X-ray (Cossel line).

As a result of the X-ray being diffracted by each of the samples 1-4, the diffraction X
The lines form various conical surfaces, and the cross section in the plane with these conical surfaces becomes the X-ray Kessel diffraction pattern.

The X-ray Cossel diffraction image is a high-sensitivity X-ray sensor 1-5 provided on the image receiving surface of the X-ray image intensifier 1-5.
-1 is formed.

In order to simplify the analysis of X-ray Cossel diffraction images, this X-ray is usually used.
The image receiving surface of the line image intensifier 1-5 is installed parallel to the measurement sample surface, below the sample (transmission cossel method) or above the sample (reflection cossel method).

The parts from the electron gun 1-1 to the X-ray image intensifier 1-5 described above are placed in a vacuum container.

The binary image processing of the crystal structure is performed along the arrow in FIG. The crystal structure of the measurement sample 1-4 is image-processed / analyzed by connecting the optical microscope 3-1 of the optical microscope image detection device 3 to an image pickup tube equipped with a high-sensitivity image pickup device, in this case, a television camera 3-2. In addition to being input to the dedicated image processor 6, the SEM image by the reflected electron beam scattered from the measurement sample 1-4 is detected by the detector 4 of the SEM image detecting device 4.
It is detected by -1 and input to the image processor 6 through the scanning converter 4-2.

Input of these SEM images and optical microscope images to the image processor 6 is performed by the input interface 5 as necessary signal processing, A / D conversion and the like.

The image processor 6 dedicated to image processing / analysis comprises an image memory 6-1, a CPU 6-2 dedicated to image processing / analysis, and a CPU 6-3 for control and editing.

Of these, the image memory 6-1 is divided into a grayscale image memory, a binarized image memory, a color dedicated memory, etc., and it is possible to increase the memory capacity and input a plurality of images in parallel. (Multi-memory channel).

The image processing / analysis-dedicated CPU 6-2 performs various kinds of processing (for example, spatial filter, grayscale conversion, binarization, masking, area division, etc.) on the image stored in the image memory 6-1 and then performs the processing. Image analysis (for example, calculation between images, feature extraction, measurement, numerical analysis, etc.) is performed.

The CPU 6-3 for exclusive use in control and editing performs activation and control of the entire system of the X-ray Cossel diffraction image automatic analyzer of the present invention, and connects the external storage device group 11 and the external input device group 12 as necessary. The data in the image memory 6-1 can be stored in a disk, a program can be created, and the entire system can be controlled using a graphics terminal or a digitizer.

The crystal structure image input to the image processor 6 is
After performing image processing by dialogue using the digitizer or light pen of the external input device group 12,
It is output as a binarized image, stored in the external storage device group 11, and displayed on the CRT of the display group 8 through the output interface 7.

Next, a mechanism for driving the sample stage and automating electron beam irradiation will be described.

The electron beam irradiation position (crystal orientation measurement position) is directly indicated on the binarized screen on the CRT by the external input device group 12,
The position of the center of gravity of each crystal grain, the crystal grain and output data,
The crystal grains to be measured are labeled in order to make a correspondence between (crystal orientation and its color image).

That is, the label number n indicating the label of the crystal grain is entered on the first surface of the image memory of which one surface is ixj pixels, and the second surface is provided with the sample stage, focusing, and electron beam irradiation (YE
An outgoing signal (1/0) indicating S / NO) is input.

For example, if the label numbers of the (i, j) pixel and the (i + 3, j) pixel in the same row and the transmitted signals are (m, 1) and (m, 0), respectively, (I + 3,
j) Pixels belong to the same crystal grain, but electron beam irradiation is performed only at the former position. The transmission signal indicating the electron beam irradiation is transmitted to the autofocus / stage controller 9-1 of the stage drive / electron gun starting / stopping device 9 through the CPU6-3 dedicated to control and editing, and is a pulse for three axes (XYZ). The sample stage 1-8 of the X-ray Cossel diffraction image observation apparatus 1 is driven by the motor 9-2, and the electron beam probe is aligned with the position designated by the (i, j) pixel of the CRT.

Further, this signal is a high voltage power source 9-3 for electron beam generation and control.
The electronic gun 1-1 is turned on / off by being transmitted to the.

(Operation) The image analysis of the X-ray Kossel diffraction image formed on the image receiving surface of the X-ray image intensifier 1-5 will be described.

The X-ray Cossel diffraction image is the arrow in Fig. 1. The crystal orientation analysis is carried out along with.

That is, the X-ray Cossel diffraction image is detected by the high-sensitivity X-ray sensor 1-5-1 provided on the image receiving surface of the X-ray image intensifier 1-5, and is input to the input interface 5 as an electric signal. Signal level processing, X
After matching the fiber of the line sensor 1-5-1 and the capacity of the image memory 6-1 of the image processor 6 (the number of pixels of one screen), A / D conversion, etc., the arrow Then, the image data is input to the image memory 6-1 of the image processor.

Since this input image is equivalent to that transmitted on a conventional X-ray film as raw data, it is stored in the disk of the display group 8 before image processing is performed, and is displayed on the CRT as necessary and photographed by the camera. .

The original image data of the X-ray Cossel diffraction image input to the image memory 6-1 is subjected to image processing necessary for image analysis based on the standard sample. In the X-ray Cossel diffraction image, the line width and the intensity of the diffraction line are not constant due to the probe diameter of the electron beam, the shape of the X-ray generation source, and the plane map of the Ewald spherical surface.

For this reason, a program is prepared in advance using a standard sample to carry out preprocessing (eg, gradation conversion, noise cut) necessary for analysis and is input to the control / edit dedicated CPU. According to the instructions of this program, the X-ray Cossel diffraction image is binarized by the image processing / analysis dedicated CPU 6-2, and the crystal orientation analysis is performed.

The method for determining the crystal orientation from the Cossel diffraction image is the method by Ferran et al. (G. Ferran & RAWood: J.Appl.Cryst.vo.
l.3 (1970)) is used. That is, when a sample is vertically irradiated with an electron beam, a pear-shaped characteristic X-ray is generated in the sample, and when the sample passes through the sample, Bragg diffraction is caused by its crystal lattice and a diffraction cone with the X-ray generation source as an apex. Is formed. This image is approximated as a quadratic curve represented by the equation (1) on the horizontal image receiving surface 1-5-1 of the X-ray image intensifier 1-5 which is vertically away from the X-ray generation source by l.

here Is an orthogonal coordinate system on the sample surface (rolling surface) parallel to the image receiving surface 1-5-1. The axis is the line of intersection between the sample plane and the (hkl) diffraction plane. θhkl is (hk
l) Bragg angle of the diffractive surface, and γ is the angle between the (hkl) diffractive surface and the sample surface. (Hkl) Positive pole diagram is sample coordinate system x
-Y-z (x-axis = RDy-axis = TDz-axis = ND) is the description of the crystal coordinate system X-Y-Z (corresponding to the unit cell vector in the case of cubic), all {hkl } It is represented as a stereo projection point of the surface normal.

That is, in equation (1) Rotation angle φ (of coordinate system and sample coordinate system xy And z are in agreement. ) And the value of γ, the (hkl) pole is determined.

In equation (1) About Of (2) Becomes

this Is the shortest distance from the origin to the (hkl) diffraction line. Let this point be p, the coordinates of the point p in the xy coordinate system are (x _p , y _p ), and the curvature of the (hkl) diffraction line at the point p is ξ _p
In other words, γ and φ can be obtained from equations (3) and (4). (However According to the equation (3), in order to determine γ, the diffractive surface index (hkl) of the arbitrarily selected diffracted line must be discriminated. For example, in the case of α iron Cossel diffraction line, the diffraction planes that satisfy the Bragg condition are {200}, {110} {211}, and {22}.
0} only. Curvature of diffraction line at point p ξ _p
Is Therefore, if a lookup table for each θhkl for γ is created, by measuring ξ _p (hkl)
Can be determined.

Next, a method of creating a (hkl) pole figure from (γ, φ) of an arbitrary (hkl) diffraction line determined by image analysis will be described.

According to the stereo projection, the (hkl) pole point showing the diffractive surface normal is represented by the point A in FIG. That is, point A has rotated φ clockwise from RD. On axis (T is the radius of the pole figure).

The (hkl) pole figure needs to show all the poles of spatially equivalent combinations of {hkl}, but from the rotational symmetry of the crystal, if it is the {200} pole, if it is the {110} pole, If three points are decided, the positions of all remaining poles can be decided.

An example of creating a (200) pole figure is shown in FIG.

Points A and B are (200) and (002) poles obtained from the Cossel diffraction line, and their measured values are (γ _A , φ _A ) and (γ _B , φ _B ). From these two points, point C (γ _C , φ _C )
To decide.

The zone axis passing through the two points A and B (the stereo projection of the great circle) is perpendicular to the intersection line ROS between the OAB surface and the rolling surface. Is decided as RAQBS. If the point is Q (γ _O , φ _O ), When The angle φ ₁ ′ formed by is expressed by the equation (6) by the angle ∠AOQ by stereo projection.

In stereo projection, the equations (8) and (9) generally hold.

tan γ _O = tan γ _A cos (φ _O -φ _A ) ... (8) tan γ _O = tan γ _B cos (φ _B -φ _O ) ... (9) Equations (8) and (9) are represented by (6) and (7). Substituting into the expression, Angle formed by Therefore, γ _O can be calculated from equation (10).

By substituting this into equation (8) or (9), φ _O becomes (1
It can be calculated by the formula 1).

Vertical to both Since both are vertical and ∠QOC = π, the point C is (1
It is determined by equations (2) and (13).

The conversion from this (200) pole figure to the (110) pole figure is point A
And B, points B and C, and points C and A, the crystal zone axes are obtained from equations (6) to (11), and the interplane angle between the {200} plane and the {110} plane And the angle between {110} and {110} planes The six {110} poles required for display can be determined from the relationship of.

Next, the conversion from the positive pole figure to the reverse pole figure will be described.

Generally, in the case of BCC crystal system, it is easy to convert the (200) positive pole figure to the reverse pole figure of ND and RD. In Fig. 3, (20
0) An example of creating a reverse pole figure of ND and RD from a positive pole figure is shown in FIGS. 4 (i) and (ii).

The inverse pole figure shows ND and RD (4th) when the (200) positive pole figure is rotated equiangularly so as to match the (200) standard projection.
It is represented by the coordinates of the drawing points N and R), but is usually represented by the one of the 48 spatially equivalent {001}-{011}-{111} stereo triangles that is closest to the origin. Therefore, the travel route is different between ND and RD. First, the method of creating the ND inverse pole figure will be described.

Of the three {200} poles, ND, that is, the origin O in FIG.
Rotate the closest one to the origin. In Figure 3 Therefore, the point C moves to the origin C'as shown in FIG. 4 (i). Point A, point B, and point O (ND) are moved equiangularly around the rotation axis to become point A ′, point B ′, and point N, respectively. In a stereo triangle containing the point N, the point N is (1
Displayed with ▲ ▼ determined by Eqs. 4) and (15).

Next, a method of creating the RD inverse pole figure will be described.

Of the three {200} poles, the one closest to RD, that is, the point A in FIG. 3 is rotationally moved to the origin to be the point A. Point B,
Points C and RD become points B ″, C ″, and R, respectively, by conformal movement about the axis of rotation. ∠RA ″ A and ∠AA ″ C ″ (Fig. 4, θ ₁ and θ ₂ ) are (16), (17)
It becomes an expression.

In the stereo triangle including the point R, the point R is (18), (1
9) determined by Is displayed.

The analysis result obtained from the above calculation is stored in the disk together with the Cossel diffraction image and the measured value, and if necessary, the plotter plots the forward and reverse pole figures.

Next, a method of creating a color map based on the crystal orientation of the metal structure will be described.

This color map can accurately and clearly display the texture of metal, especially the preferential formation of crystal orientation (eg, secondary recrystallization nucleation of grain-oriented silicon steel, {111} texture formation of cold-rolled steel sheet). The situation, the non-uniformity within the plate thickness of the hot rolled texture, etc.) can be grasped in detail and accurately.

The color display on the CRT is R (red), G (green), which is provided in the image memory in the image processor.
Similar to a normal grayscale image, each gray level is input to the color memory composed of three B (blue) planes, and the colors are mixed to superimpose colors. According to this, if each gray level of each RGB is 256, 256 ³ colors can be displayed.

As a color display method of crystal orientation, the three primary colors of R, G, and B are {011} and {11} of the basic stereo triangle of the inverse pole figure, respectively.
1}, {001} poles are placed, and the angle from each vertex is used as the gray level to perform color mixing. That is, if the coordinates of an arbitrary point P in the stereo triangle are (ω, φ), (ω:
Latitude, φ: longitude) Color function at point P Is expressed by equation (20).

here C = 1- (a + b) R = Rad ・ G = Green ・ B = Blue primary colors a ・ b ・ c are R ・
When displaying the gray level ND of G and B, the point P corresponds to the point N in FIG. 4, so from equations (14) and (15), The point N (ω, φ) is calculated from equations (21) and (22), and
by computing a, b, c Is determined.

Similarly, when displaying RD, since point P corresponds to point R in FIG. 4, from equations (16) to (19), By calculating the point R (ω, φ) from equations (23) and (24) and calculating a, b, and c in equation (20), Is determined.

Thus determined (A, b, c) and (A, b, c) are a, b, and c input in parallel to the pixel area corresponding to the crystal grain of the crystal orientation of the color image memory with three faces of R, G, and B of ND and RD. . Each R, G, B color screen and 2 of grain boundaries per measurement area
A color map of crystal orientation is created by superimposing the digitized screen on the color CRT.

In short, the configuration of the scanning electron microscope is used to construct an X-ray image intensifier, an image processor for storing / processing / analyzing the image, and a display device for displaying the image after the analysis. In a multi-channel system that can be used as a diffraction image analysis device, in which the image memory of the image processor stores the output from the X-ray image intensifier, and the scanning image and the optical microscope image can be input and stored through the scanning converter or the image pickup tube. Yes, after processing the image of the metallographic structure, edit the crystal orientation measurement coordinates of the image processor using the digital image output to the display device.
By inputting to the control CPU, auto focus /
By driving the sample stage with the stage controller, the focus and sample position are automatically controlled, and the electron beam is automatically turned ON / OFF by the high voltage control, so that the sequentially input Cossel diffraction image is binarized, and from the origin Two or three
By measuring the coordinates of the foot of the perpendicular line drawn on the 200 or 110 diffraction line and the curvature of the diffraction line at this point, (hkl) positive pole figure, ND reverse pole figure, RD reverse pole figure, and binary metallographic structure After automatically analyzing the color image of the crystal orientation by the opposite poles of ND and RD using the digitized image with the image processor, display the measurement data together with the analysis data, the pole figure and the color map on the display device including the plotter and color CRT. indicate.

(Effect of the Invention) The X-ray Cossel diffraction image automatic analysis apparatus of the present invention can realize sequential automatic irradiation of electron beams, automatic creation of a pole figure, and color mapping in the diffraction image observation system.

[Brief description of drawings]

FIG. 1 is a block diagram of an X-ray Cossel diffraction image automatic analyzer according to the present invention, FIG. 2 is a relationship diagram between measured values and a positive pole figure, and FIG. 3 is an explanatory view of an example of creating a (200) pole figure. The figure is an explanatory view of an example of creation between the ND and RD reverse pole figures from the positive pole figure. 1 ... X-ray Cossel diffraction image observation device 1-1 ... Electron gun 1-2 ... Converging lens 1-3 ... Objective lens 1-4 ... Sample 1-5 ... X-ray image intensifier 1-5-1 ... High-sensitivity X-ray sensor 3 ... Optical microscope image detection device 3-1 ... Optical microscope 3-2 ... TV camera 4 ... SEM image detection device, 4-1 ... Detector 4-2 Scanning converter 5 Input interface 6 Image processor 6-1 Image memory 6-2 Image processing / diffraction CPU 6-3 Control / editing CPU 7 Output interface 8: Display 9: Stage drive / electron gun drive stop device 9-1: Autofocus / stage controller 9-2: X-Y-Z pulse motor

Claims (1)

[Claims] 1. An X-ray Kossel diffraction image observation apparatus comprising an X-ray image intensifier, an image memory for storing the output thereof, and a signal processing device for reading out the data stored in the image memory and performing signal processing, and the Kossel diffraction. An image processing device for obtaining the shortest distance portion from the origin on the screen on the line, an image analysis device for obtaining the curvature of the Cossel diffraction line at the shortest distance portion, and a conversion device for obtaining the crystal orientation from the obtained curvature of the Cossel diffraction line, An X-ray Cossel diffraction image analyzer comprising a display device for displaying the obtained crystal orientation, and an optical microscope image detection device (3) for detecting the crystal structure of a sample.
And S that detects the SEM image by the backscattered electron beam scattered from the sample.
EM image detector (4) and input interface (5) for processing and converting the signals of these optical microscope image, SEM image and X-ray Cossel diffraction image
And an image memory including a grayscale image memory for storing image data, a binarized memory for storing binarized data of crystal grain boundaries, and a color memory for storing color image data (6-
1), CPU for image processing / analysis for binarizing X-ray Cossel diffraction image and analyzing crystallographic orientation (6-2), Controlling / editing for inputting crystallographic orientation measurement coordinates and starting and controlling the entire system The image processor (6) including the dedicated CPU (6-3) and the output signal of the control / edit dedicated CPU (6-3)
The sample position in the line-COSSEL diffraction image observation apparatus 1 is moved,
Also, a stage drive / electron gun start / stop device (9) for automatically starting and stopping the electron gun, and a color display device (8) for displaying a color image
And an plotter that creates a pole figure, an automatic X-ray Kessel diffraction image analyzer.