JPH0114664B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a solid local gas analysis method and apparatus for locally analyzing gas components dissolved in solids, particularly metals, with high sensitivity.

Solid local gas analysis is becoming increasingly important in the field of materials research for the development of higher quality metal materials, mainly steel. Metal materials contain many impurities, and recently the negative effects of gas components such as hydrogen H, nitrogen N, sulfur S, and carbon C on materials have become a problem. For example, H in steel materials is cited as a cause of delayed fracture and hydrogen embrittlement. Conventionally, the gas components mentioned above that degrade materials are collected from a minute part of a sample and analyzed using an IMA (ion microanalyzer) or an EPMA (electron probe microanalyzer). I had no choice. However, the former
IMA is a device that sputters and ionizes a sample with a narrowly focused ion beam, and then analyzes this with a mass spectrometer.In principle, it is configured to be able to analyze the above-mentioned material occlusion gas with the high sensitivity of PPb, but the device is complicated. It is expensive and has a low penetration rate, and there is a feeling that it is currently not fully developed as a practical local analysis device. The latter EPMA is
This method performs elemental analysis and other functions by irradiating a sample with a narrowly focused electron beam and comprehensively utilizing the various signals (electrons, X-rays, light, etc.) generated therefrom. This is the mainstream device. However, this EPMA not only cannot detect hydrogen H among the above material storage gases, but also
The detection sensitivity for gas components such as nitrogen, nitrogen, sulfur, and carbon is low, making it inferior to the above-mentioned IMA as a local gas analyzer. As described above, there is still no appropriate technical equipment for high-sensitivity analysis of occluded gases in the above-mentioned materials, which corresponds to local analysis of metal materials, and this has become a major obstacle in the development of the aforementioned high-quality materials and in investigating the causes of accidents. The current situation is such that a solution to this problem is particularly strongly desired by the steel industry.

This invention was made in view of the above-mentioned current situation.
By skillfully combining the features of both EPMA, which has made remarkable progress in the field of microanalysis of solid local areas, and IMA, which is excellent in principle in gas analysis, it provides stable performance, easy operation, and low analysis costs. The object of the present invention is to provide a solid-state local gas analysis method and an apparatus for the same, which can analyze all gases harmful to materials with high sensitivity. That is, a gas stored in a solid is excited and released in a vacuum atmosphere, this gas is collected by a jet stream of inert gas, and a mixture of the picked up gas and the above inert gas is subjected to mass spectrometry analysis. A method for local gas analysis in a solid is characterized in that the gas stored in the solid is analyzed, a sample chamber mechanism that keeps a solid sample in a vacuum atmosphere and allows the position of the sample to be moved slightly at will, and an electron beam. or a solid-state local gas analyzer comprising a solid-state occluded gas excitation device comprising a charged particle beam irradiation mechanism, a spark discharge mechanism, or a mechanical stimulation mechanism; and an inert gas jet flow mechanism and a mass spectrometer. It is something.

Embodiments and devices of the invention will be described below with reference to the drawings. FIG. 1 is a diagram explaining the basics of the method. 1 is a solid sample, for example, Fe with a diameter of 20
A sample with a thickness of 10 mm is loaded into the sample fine movement device (not shown) in the sample chamber of EPMA. 2 is
An incident electron beam irradiated from the electron optical system of the EPMA forms a perfect circular electron beam spot 3 of 1 μm or smaller on the surface 1A of the sample 1. The electron beam 2 is designed to arbitrarily scan the sample surface 1A over a maximum range of about 10 mm ² . Among the electromagnetic waves excited by the collision of the incident electrons 2, 4 is the most important characteristic X-ray used for analysis, and qualitative and quantitative analysis and other measurements of the elements at the irradiation point 3 are performed using this. . Reference numeral 5 represents absorbed electrons, and the incident electrons repeatedly collide with atoms in the sample 1, exciting secondary electrons and electromagnetic waves of various energies, and then flow to the ground as a current. This is also called the sample current and is measured with an ammeter μA to monitor the density of incident electrons. Other secondary electrons, photons, etc. (not shown) are emitted from the irradiation point 3, but since they are not related to this invention, their explanation will be omitted. Reference numeral 6 indicates gas released from the solid sample 1. Of the gas 6, a portion of the sample surface 1A separates due to electron collision, and gas within a few μm, for example at the grain boundary, separates due to electron beam heating. and release it. For this electron beam heating, if the sample 1 has the above dimensions, the applied voltage is 40 kV, and the sample current (5 above) is applied.
1μA, when the diameter of electronic spot 3 is 1μ, spot 3
The temperature is approximately 400℃. This is Castaing's equation θ _n = 1.14 x 10 ^-3 W/Cd = 1.14 x IV/c
d (°C) (I: μA, V: kv, c: thermal conductivity, d:
μ). Like this normal EPMA
It is possible to fully release the stored gas under the usage conditions.

The above is one of the methods for exciting local gas in a solid, which is one of the requirements of the present invention. Next, the means for collecting the emitted gas will be explained. 7 is an inert gas, for example, an Ar gas cylinder; 8 and 9 are Ar gas leak nozzles and their suction ports. Ar gas 10 is 10 ^-2 ~
A jet flow is created as shown by arrows A and B with a leak pressure of about 10 ^-3 Torr, and sample chamber 1 is placed in a high vacuum (10 ^-5 Torr).
It serves as a carrier gas for the above-mentioned released gas 4 which is about to be dispersed into 1, and about 50% or more of the total amount of released gas in the sample is collected. The suction port 9 receives Ar gas 1 through a conduit.
0 and the sample discharge gas 6 are introduced into the mass spectrometry system 12 outside the sample chamber.

FIG. 2 is a diagram showing an embodiment of a means for improving the efficiency of picking up the discharged gas 6. As shown in FIG. Carrier gas 10 above 10 ^-2 to ^{10 -3} Torr
Since the height of the gas pressure affects the scattering of the incident electron beam 2, a cover is provided around the spot 3 as shown in 13, and the leak pressure P of the carrier gas 10 is made as low as possible (close to vacuum). 13A
is an incident window for the electron beam 2. However, in this case, in order to perform normal X-ray analysis, the cover 13 is made removable, or the window 15 that emits characteristic X-rays 4 and other signals The released gas 6 is efficiently collected using the sample box 14 which can be opened and closed by operation. Figure 3 1
Reference numeral 7 denotes an objective lens of the electron optical system, and θ° is the X-ray extraction angle, which is usually 52.5°, and the opening degree of the window 15 is determined by this. FIG. 4 is a diagram showing a means for further promoting gas release and picking up a large amount of gas in addition to the above structure. 18 is the tip of a manipulator that is remotely operated from outside the apparatus, 19 is a crystal on the sample surface 1A, and 20 is a grain boundary. By applying mechanical stimulation such as poking or pulling the sample surface 1A with the sharp tip 18A of the manipulator 18, cracks are generated in the grain boundaries 20 and the gas release efficiency of the electron beam 2 is promoted. It is something. FIG. 5 shows a gas discharge excitation means that uses the manipulator 18 as an electrode and connects an appropriate DC high voltage power source 21 to cause a spark discharge 22 to be generated at an arbitrary location on the sample surface 1A.
By using this method in combination with the above-mentioned electron beam irradiation, the gas release efficiency is significantly improved.

The above are various methods for performing local gas analysis using the sample chamber of EPMA, but this invention
The present invention is not limited to EPMA, but also includes using IMA, replacing the incident electron beam 2 in FIG. 1 with an ion beam, and making the other configurations substantially the same as in FIG. 1. Also the second
It is also possible to use Figures 5 to 5.

Since this invention is configured as described above,
This method overcomes the disadvantages of conventional local gas analysis of solids using existing local analyzers, and satisfies the following requirements for gas analysis in solids, especially metals. In other words, (1) enables local storage gas analysis corresponding to SEM images (scanning electron images) and X-ray microanalysis using local analyzers. (2) makes it possible to efficiently collect a large amount of the above gas components. (3) Analysis of _H2 is also possible.

[Brief explanation of drawings]

Figure 1 is a diagram explaining the principle of the analytical method of this invention, Figure 2
Figure 3 is an explanatory diagram of an example device for improving analysis efficiency, Figure 4 is an explanatory diagram of a mechanical stimulation method as a means of gas release, and Figure 5 is an explanatory diagram of a spark discharge method as a means of gas excitation. be. DESCRIPTION OF SYMBOLS 1... Solid sample, 2... Incident electron beam, 3... Electron beam spot, 4... Characteristic X-ray, 5... Absorbed electron (sample current), 6... Gas released from solid sample, 8... Carrier gas leak nozzle, 9... Gas suction port, 1
0...Carrier gas, 11...High vacuum sample chamber, 12
...Mass spectrometry system, 13...Spot part cover, 14...
Sample box, 15... Window, 16... Window cover, 17... Objective lens of electron optical system, θ°... X-ray extraction angle, 18... Tip of manipulator, 19... Crystal of solid sample, 2
0... Grain boundary, 21... DC high voltage power supply, 22... Spark discharge.

Claims (1)

[Claims] 1. Excite and release the gas stored in a solid in a vacuum atmosphere, collect this gas with a jet stream of inert gas, and mix this picked up gas with the above inert gas. A method for local gas analysis in a solid, characterized in that the mixture is subjected to mass spectrometry to analyze the occluded gas in the solid. 2. The solid local gas analysis method according to claim 1, wherein the excitation for releasing the gas stored in the solid is performed by electron beam irradiation. 3. The method for local gas analysis in a solid according to claim 1, wherein the excitation for releasing the gas stored in the solid is performed by irradiation with a charged particle beam. 4. The method for local gas analysis in a solid according to claim 1, wherein the excitation for releasing the gas stored in the solid is performed by a spark discharge. 5. The method for local gas analysis in a solid according to claim 1, wherein the excitation for releasing the gas stored in the solid is performed by mechanical stimulation. 6. A sample chamber mechanism that keeps a solid sample in a vacuum atmosphere and moves its position arbitrarily, and an excitation device for gases stored in a solid, which consists of an electron beam or charged particle beam irradiation mechanism, a spark discharge mechanism, or a mechanical stimulation mechanism. A fixed local gas analyzer comprising: a jet flow mechanism for inert gas; and a mass spectrometer.