DE1248174B - X-ray tubes for X-ray diffraction analysis - Google Patents

Description

FEDERAL REPUBLIC OF GERMANY

GERMAN

PATENT OFFICE

EDITORIAL

Int. Cl .:

Number:
File number:
Registration date:
Display day:

HOIj

H05g

German class: 21g-17/02

1 248 174
Y738 VIII c / 21g
September 10, 1963
August 24, 1967

The invention relates to an X-ray tube for X-ray diffraction analysis having one of several different substances selected according to their characteristic radiation Anticathode.

Each element radiates when electrons accelerated by a sufficient voltage hit it a series of X-rays with characteristic wavelengths. The elements with the are characteristic X-rays most commonly used for X-ray diffraction systems z. B. Chromium, iron, cobalt, copper and molybdenum.

Mostly, one of these elements is used as a material for the anticathode according to the purpose of use selected, which emits an X-ray beam for measurement. If the test sample is changed, the anticathode must therefore be used for the measurement be replaced. In the case of special examinations, however, it is necessary to take measurements alternately Use of two or more characteristic ones that differ from one another in terms of wavelength Perform X-rays. X-ray tubes with an anticathode made of a pure metal are therefore awkward to use for X-ray diffraction analysis.

True, it is an X-ray tube for X-ray diffraction analysis known whose anticathode consists of several different, according to their characteristic Radiation is composed of selected substances. Here the anticathode consists of adjacent plates or blocks of these substances (British patent 574109).

The anticathode hit by the electron beam sends the characteristic X-rays of the substances in question, the individual rays, however, in different directions be sent out. Between these directions the rays are constantly changing in their ratio mixed. Measuring this ratio is not easy. So it is very difficult to get one X-ray camera or a measuring device set in a direction in which the two characteristic X-rays are in a desired intensity ratio to one another.

X-ray tubes are also known whose anticathode consists of several axially displaceable disks or rings are made of different metals. By moving the anticathode, a desired one becomes Anti-cathode material hit by the electron beam and a desired X-ray beam emitted at constant wavelength (British Patent 858,416).

X-ray tube for the
X-ray diffraction analysis

Applicant:

Yawata Iron & Steel Company, Limited, Tokyo

Representative:

Dr.-Ing. A. Vogt, patent attorney,

Baden-Baden, Beuttenmüllerstr. 8th

Named as inventor:

Shinichi Nagashima,

Morihiro Tsuiki,

Kitakyushu City, Fukuoka Prefecture (Japan)

Claimed priority:

Japan September 15, 1962 (39 856)

Such an X-ray tube requires a device for moving the anticathode from the outside in order to change the wavelength of the characteristic X-ray beam. This device also requires a vacuum pump to emit X-rays. A melted tube is not possible with this device.
X-ray tubes are also known whose anticathodes consist of binary or ternary alloys. Such X-ray tubes are used for medical purposes or for material testing, whereby bodies or objects are x-rayed and observed in the form of light and shadow on a fluorescent screen or recorded on a photographic plate (e.g. Austrian patent specification 219168).

The invention is based on the object of an X-ray tube for X-ray diffraction analysis to propose the purpose of simultaneous application of the characteristic radiations different substances deliver these radiations at the same time.

This object is achieved according to the invention in that the anticathode consists of a binary or ternary Alloy of these substances is made.

A Mo-Fe-, Cr-Co-, Co-Fe- or Fe-Ag alloy and a Co-Cu-Fe alloy used as the ternary alloy.

In the following the invention is explained in more detail with reference to the drawings.

709 638/432

Fig. 1 (A) and 1 (B) show schematically two arrangements for measuring material stresses by means of X-rays according to the method of X-ray diffraction analysis;

Figure 2 shows a longitudinal section through an X-ray tube dar;

Figure 3 is a surface pole figure of a mild steel and

Fig. 4 is a back-ray image of pure iron, which is made by means of a device designed according to the invention X-ray tube was manufactured.

In general, X-ray diffraction analysis uses continuous X-rays and characteristic X-rays are used. Continuous X-rays are mainly used used to avoid tepid shots while using a single crystal characteristic X-rays in various X-ray procedures or measurements, e.g. B. according to the crystal powder method or the rotary crystal method, which are used for structural analysis of substances are suitable.

The invention allows X-ray diffraction analysis for structural study or recording of surface pole figures using different characteristic X-rays with only a single X-ray tube with an anticathode made of a metal alloy of two or more Metals easily and quickly carried out, these two or more characteristic X-rays send out. This eliminates the laborious exchange of the X-ray tube and readjustment the working position of the X-ray tube avoided, which was the case with diffraction analyzes with the previously usual X-ray tubes was necessary.

Another advantage of the metal alloy anticathode is that it, e.g. manganese-bronze alloy, is very easy to manufacture, while the usual anticathodes are made of pure metal are very difficult to depict.

The anticathode in conventional X-ray tubes is made from a single crystal of a pure metal been. Examples of such metals are tungsten for a continuous X-ray process and Chromium, iron and cobalt, nickel, copper and molybdenum for procedures with characteristic X-rays. In the X-ray diffraction analysis, except for the Laue method, characteristic X-rays of a certain wavelength are used. However, they contain continuous X-rays and some other rays of unwanted wavelength. Such rays must can therefore be removed by means of a filter or a mono-atomic crystal, even if an anti-cathode made of pure metal is used. Therefore, a metal of the highest purity is usually considered Anticathode of X-ray tubes used.

The anticathode made of such a metal of the highest purity is sealed in an X-ray tube. A high voltage is applied to this in order to generate X-rays which are directed against a camera or an X-ray diffraction apparatus for photography or measurement can be directed.

In general, the measurements can be made using a single characteristic X-ray beam be performed, but some measurements must be made for each test sample for some reason performed twice with two different characteristic X-rays. For example When measuring the residual stress in iron and steel, the residual stress in the plane (211) measured using the characteristic X-ray S beam from the chrome anticathode (Cr-Ka), and then the tension is measured in another plane (310) in the same position of the same test sample, with a different characteristic Radiation from another cobalt anticathode

ίο (Co-Ka) is used. The following is the invention explained in more detail with reference to the drawings.

In Figure 1, the schematic arrangements for X-ray diffraction measurement shows, 1 is an X-ray tube, 2 a test sample, 3 a radiographic Film and 4 a counter. For the radiographic measurement, as shown in Figure I (A) can be seen, the sample 2 in a vertical position, represented by the solid line, to the incidence of the

ao brought X-rays, which give a roentgenogram on the film 3. Circular diffraction images are generated on the film by the X-rays, which are diffracted in the direction of arrow 1 by the angle 2 Θ against the direction of incidence. Then the sample is moved at an angle of 45 ° with respect to the direction of incidence of the X-ray beam, as shown by the broken line, whereby a similar image is formed on the film. In this way it is possible to calculate the stress in a certain crystal plane from the angular setting of a pair of diffraction lines for two different positions of the samples at 90 and 45 °. Finally, the X-ray tube is replaced by another with an anticathode made of a different metal and the position of the camera is adjusted accordingly, obtaining two further X-ray images with two different positions of the samples at 90 and 45 ° with respect to the incidence of the X-ray beam . The stress is found in a second crystal plane, which is regarded as the residual stress.

In a similar way, this measurement can be carried out with a Geiger counter, as shown in Figure 1 (B), after which the Geiger counter is moved in a range of the diffraction angle 2 Θ from 158 ° to 164 °, and the angle of the diffraction line is measured .

The voltage in the plane (310) is determined by using a cobalt anticathode from two different widths of the diffraction angle 2Θβ , as results from two successive measurements at two different positions of the sample at 90 and 45 °. Another value of the voltage in the plane (211) is obtained by using a different X-ray beam which is generated when the X-ray tube with the cobalt anticathode is replaced by an X-ray tube with an anticathode made of chromium.

The measurement of voltages using two consecutive X-ray applications is very complicated because two different characteristic X-rays are applied to the same sample have to be changed, the anticathodes and the position of the camera to the X-ray apparatus must be set up anew each time the anticathode is changed.

Another example of the same measurement, the laborious and frequent replacement of the anticathode

required is the measurement of X-ray pole figures to determine the preferred orientation of a metal layer. A perfect image can only be obtained with this measurement if two different successive measurements, the transmission and reflection method, are used. For example, when testing mild steel and silicon steel, the pole pattern in the range from 0 to 60 ° is determined by measuring the primary diffraction of the plane (110) using an X-ray tube with a molybdenum anticathode and the positions from 0 °, starting at the circumference, to 60 °, as can be seen in Figure 3. The same pole image is then determined in the range from 40 to 90 ° (center) by measuring the diffraction of the plane (110) using another anticathode made of iron and the positions from 40 to 90 ° are marked on the same image, as is also shown in Fig 3 can be seen. With this measuring method, too, the X-ray tube must be readjusted each time the anticathode is changed.

The invention overcomes these disadvantages of the usual practice and allows the successive, measurements described above using a single X-ray tube in a very short time and without reduction the accuracy of the results.

The combination of metals for the anticathode can be according to the subject of measurement vary. To measure the residual stress in iron and steel, e.g. an anticathode is made from a Cr-Co alloy and an anticathode made of Ag- or Mo-Fe for measuring an X-ray pole image. In addition to the above-described two-element anticathodes, according to the invention three elements can also be used.

To determine a substance z. B. cobalt, copper and iron anticathodes used individually. For some substances, however, the relative intensity of the diffraction lines varies depending on the anticathode material. To determine a substance with such an element that has such fluctuations caused, it is advisable to measure the same sample by replacing the Repeating anticathode. During the measurements for the determination of a substance as a routine work are extraordinarily numerous, there are many cases in which a content of a specific element in the substance makes it necessary to change the anticathode depending on the substance. In such a case, an X-ray tube with an anticathode is made from a ternary alloy Cobalt, copper and iron in connection with a scintillation or proportional counter and If a pulse counter is used to optimally select a desired wavelength, the measurement can be carried out with greater efficiency and better measurement accuracy.

An exemplary embodiment of the invention will now be described.

Figure 2 shows a longitudinal section of an X-ray tube in which 5 a glass tube, 6 an exit window for the X-rays, 7 a line for 6g the cathode, 8 an anti-cathode, 9 an anode, 10 an anode base, 11 inlet and outlet tubes for the cooling water the anode and 12 mean a radiation protection cover. The interior 13 of the X-ray tube is kept under vacuum.

Figure 4 shows an X-ray diagram in which diffraction of two different crystal planes (310) and (211) of pure iron was obtained by means of X-rays. This was generated by an X-ray tube designed according to the invention with an anticathode made of Cr-Co in a mixing ratio of 1: 1. The outer pair of dark and light diffraction rings and the inner pair represent double rings (211) and (310) which are caused by the Κ _α ι and K _a 2 rays of chromium and the K «i and K _a2 rays, respectively of cobalt.

Other two-metal alloys, e.g. B. Fe-Mo and Co-Fe are used as anticathodes and anti-cathodes made of three elements such as Co-Cu-Fe are for the practice of the invention expedient.

The advantages achieved by the invention are in particular that when using a Alloy as an anticathode the ratio of the alloy components in the alloy is constant and that the ratio of characteristic X-rays emitted from the alloy in each direction is constant.

The X-ray tube according to the invention also offers the advantage that in X-ray diffraction analyzes, characteristic X-rays of a desired Wavelength can be selected from the X-rays emitted from two windows can.

The tube can be manufactured by the usual method as for the fused-off X-ray tubes because the anticathode has no moving parts.

The X-ray tube according to the invention thus has the further advantage that when choosing a desired one Wavelength, e.g. B. by switching on a monochromator, the X-ray tube is not actuated needs to be.

Claims (3)

Patent claims: 1. X-ray tube for X-ray diffraction analysis with one of several different, anticathode composed of substances selected according to their characteristic radiation, characterized in that the anticathode consists of a binary or ternary alloy of these substances. 2. X-ray tube according to claim 1, characterized in that the anticathode consists of a Mo-Fe, Cr-Co, Co-Fe or Fe-Ag alloy is made. 3. X-ray tube according to claim 1, characterized in that the anticathode consists of a Co-Cu-Fe alloy is made. Considered publications:
German Patent Nos. 392703, 472 661, 581227, 719 317; Austrian Patent No. 219 168;
French Patent No. 615 280;
British Patent Nos. 574109, 858 416. 1 sheet of drawings 709 638/432 8.67 © Bundesdruckerei Berlin