SU441489A1 - The method of determining the size of the homogeneity region of the distribution of chemical elements in solids - Google Patents

Description

one

The invention relates to a method for determining the size of the homogeneity region of the distribution of chemical elements in solids. The invention can find application in the study of various physical properties of solids, depending on their chemical micro-inhomogeneity, in particular in the study of structural materials obtained by powder metallurgy methods.

The purpose of the invention is to improve the accuracy of determining the size of the homogeneity region of the distribution of chemical elements in solids.

The goal is achieved by gradually scanning the electron X-ray spectral analyzer with an unfocused electron beam along an arbitrary straight line segment on the thin section of the sample of the analyte. At the same time, simultaneous and continuous recording of the intensity of the characteristic

x-ray radiation of a specific chemical element. The normal operation of the X-ray spectrometer when the electron beam is defocused is ensured by appropriate adjustment of the spectrometer. It is tuned in such a way that any movement of the focused beam within the region of the corresponding pure standard visible in the optical microscope does not lead to a change in the intensity of the detected radiation. This is achieved by opening the aperture stop of the analyzer crystal and the limiting stop of the x-ray count counter.

The proposed method was tested on a micro X-ray analyzer fAAP-I domestic design.

The sample obtained by pressing a mixture of finely dispersed powders of titanium and boron was investigated, the sizes of the homogeneity region of distribution were determined, titanium Chemical heterogeneities represented dispersed particles of metallic boron, randomly 1) distributed in the volume of the matrix of titanium boride TC & I registered the characteristic X-ray radiation Td / tl, its intensity was recorded as a curve on the diagram by me with a recorder tape. Curves of changes in the intensity of radiation T / s, obtained with different diameters of the electron beam, are shown in FIG. 1-5. In all the graphs, the ordinate shows the X intensity of the recorded radiation, relative units and on the abscissa axis is the length of the segment L, µm, along which the scanning is performed, the device operated at the following parameters: Accelerating voltage. KB25 Electron beam current, μI Diameter of a focused beam, µm 4 Sample movement speed, µm / sec Chart strip speed, mm / min Instrument statistical error,% Beam diameter was preliminarily estimated by the size of the light and fluorite single crystal, the diameter was measured using a wedge method . At first, a focused BaHHbJivi was scanned with an electron beam along an arbitrary rectilinear cut on the sample jlif of the sample under study, and the curve of the change in the intensity of the radiation TT / s was shown in Fig. 1. One of this curve corresponds qualitatively to a change in the concentration of titanium along the scanning line. Dispersed inclusions of metallic boron are recorded on this curve as dips. Then, gradually by defocusing the beam, by means of changes in the current in the object lens of the electron-analytic column of the microanalyzer, they were scanned along the same segment. Figures 2, 5 and 4 show the changes in the intensity of the radiation 71 / obtained with beam diameters of 18, 30 and 48 µm, respectively. As can be seen from the drawing, as the diameter increases, the smoothes out more, and their spreads approach the statistical error of the instrument. Continuing the operations described, we finally obtained an intensity change curve, the scatter of which is equal to the statistical error of the instrument. This indicates that the concentration of titanium in the region irradiated by the electron beam at each instant of time is constant. Such a curve of the change in the intensity of radiation corresponding to a beam diameter of 75 µm is shown in FIG. 5. A further increase in the beam diameter does not alter the variations in the measurement curve of the radiation intensity. The minimum beam diameter, in which the variations in the intensity curve of the detected radiation is equal to the static error of the instrument, determines the size of the homogeneity region of the distribution of the element being detected in the analyzed substance. In the example, this diameter is 75 microns. According to the proposed method, the dimensions of the homogeneity region of the distribution of chemical elements are determined as follows. Along an arbitrarily selected rectilinear section on the thin section of the test substance, an electron beam is scanned, continuously and smoothly increasing its diameter. At the same time, the intensity of the characteristic X-ray radiation of the element being detected is recorded simultaneously on the chart tape of the recording device. Scanning is carried out to technical support until the scatter of the recorded curve becomes equal to the statistical error of the instrument. The dimensions of the homogeneity region of the distribution of this element are determined by measuring the corresponding beam diameter. The range of diameters of the homogeneity region, determined by the attached method, depends on the design features of the device used. The lower limit of this range is determined by the diameter of the focused electron beam, and the upper by the size of the sample area visible in the optical microscope. SUBSTANCE OF THE INVENTION Method for Determining Dimensions

The homogeneity of the distribution of chemical elements in solids is that the test substance is scanned along an arbitrarily chosen rectilinear segment with an electronic device and at the same time the intensity of characteristic radiation is recorded, characterized in that, in order to improve the accuracy of measurements, the electron beam will gradually defocus until until the scatter of the intensity curve of the characteristic radiation becomes equal to the statistical measurement error, and the size of the region omogennosti determined shnimalnym diameter defocussed electron beam.

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