JP2000266699A - Method and apparatus for evaluating degree of deterioration of material - Google Patents

Abstract

PROBLEM TO BE SOLVED: To evaluate the degree of deterioration of a material by establishing an easy non-destructive measuring method high in the sensitivity to a minute precipitate simultenesouly with the identification of the concn. of spot flaws in an inorg. material. SOLUTION: A material 2 to be evaluated is irradiated with positive electrons e+ from a positive electron source 1, both of γ-rays (γ1, γ2) in a directions opposite to each other by 180 deg. generated at a time of the extinction of positive electrons are simultaneously measured by semiconductor detectors 3, 4 and one counted simultaneously by a simultaneous count circuit 5 is discriminated to obtain momentum distribution. By this constitution, the energy resolving power is enhanced and an energy spectrum in the vicinity of 511 keV can be obtained. At the same time, the ratio of a matrix element and a precipitation part element to positive electrons along extinct γ-rays and the axial component of electron momentum [wherein the difference of extinct γ-rays in an opposite direction is divided by light velocity (c)] is taken. By utilizing a feature such that positive electrons flow in a direction of smaller affinity by the difference of positive electron affinity, the size distribution of a precipitate having an element small in affinity in its compsn. can be grasped. From this, a degree of deterioration of a material can be quantitatively evaluated.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method and an apparatus for evaluating the degree of material deterioration caused by positrons for evaluating the mechanical strength of an inorganic material caused by changes in point defects and precipitates by nondestructive measurement.

[0002]

2. Description of the Related Art As typical physical properties of soundness and quality of materials, there are mechanical strength characteristics. Mechanical strength is known to be closely related to its structure and defects, and is an important index in terms of safety, production cost, and product management.

It is known that the evaluation of the precipitate size distribution and the point defect concentration in inorganic materials such as metals, ceramics and semiconductors are closely related to mechanical strength. In addition, since it is closely related to electrical characteristics, it has also attracted attention in terms of product management and development.

The mechanical strength is generally measured as a destructive test determined by measuring a physical quantity before or after or by breaking a standard (eg, JIS) test piece made of the material. It is a target.

[0005] The mechanical strength can be determined from the results of microstructure observation.
It is sometimes performed as a non-destructive test using theoretical and regression equations. Non-destructive testing is often used as a complement to destructive testing. However, the nondestructive test can be repeatedly performed, and thus is often advantageous in terms of statistical accuracy and test cost.

It is known that defects in a material often interact with precipitates. In particular, point defects and line defects have a remarkable interaction. Therefore, knowing the physical behavior of a defect and a precipitate in a material may predict a change in mechanical strength to some extent.

As a method for evaluating mechanical properties accompanying a change in the distribution of precipitates and the concentration of point defects, there are mechanical tests such as a Charpy impact test, a tensile test, and a hardness test as a fracture analysis method. Since these mechanical tests are completed evaluation tests, the reliability of the data is high.

[0008]

However, it is necessary to prepare a dedicated test piece for monitoring,
As in the case of a soundness evaluation test, which has a characteristic that changes with time and is performed as needed, it is necessary to prepare a large number of test pieces. In the quality control test, it is necessary to manage the correspondence with the article. Since these are high test costs and destructive tests, it is necessary to always pay attention to the procurement and management of test pieces.

In general, fine precipitates are identified by observation using a transmission electron microscope (TEM) or a scanning electron microscope (SEM). However, very small precipitates of 0.5 nm or less are difficult to observe. Further, the electron microscope has problems such as a limited sample size and analysis in a vacuum, and is not suitable for on-site measurement.

[0010] In addition, it is necessary to prepare a special sample using various methods depending on the material, and there is a case where the sample cannot be prepared even if the test piece is successfully collected. For point defects, TE
M can be observed, but has the same problem as the precipitate.

As a method of nondestructive analysis of the distribution of precipitates and the concentration of point defects, there is a method of measuring diffraction and scattering using neutrons, ions and electrons. These require special equipment such as reactor accelerators and can be measured at the laboratory level. However, it is difficult to identify a fine precipitate of about 1 nm. As another method, for the defect concentration, there is a method of measuring the electric resistance after grasping the correlation with the electric characteristics, but it is not easy to establish the correlation.

SUMMARY OF THE INVENTION The present invention has been made to solve the above-mentioned problems, and the point defect concentration and the precipitate size distribution can be simultaneously measured using positrons to evaluate the deterioration of the material by a simple and nondestructive method. An object of the present invention is to provide a method for evaluating the degree of material deterioration and an apparatus therefor.

[0013]

According to the first aspect of the present invention, there is provided a method for evaluating a degree of deterioration of a material comprising two or more types of elements, the method comprising: emitting a positron from a positron source to evaluate the degree of deterioration. When the positrons are accumulated from the matrix element of the material to the atomic aggregate of the additional element by the positron emitted from the source, the kind of the aggregate of the additional element is determined by utilizing the fact that the momentum distribution differs depending on the element. It is characterized by.

According to the present invention, a non-destructive measuring method which is highly sensitive to fine precipitates and simultaneously obtains information on precipitate distribution and the like at the same time as the point defect concentration is established. The degree can be evaluated.

That is, by simultaneously measuring both 180-degree opposite γ-rays generated at the time of positron annihilation, the energy resolution is improved, an energy spectrum near 511 keV is obtained, and simultaneously the positrons and electrons along the annihilation γ-rays are obtained. The ratio of the parent element to the element of the precipitation part with respect to the axial component of momentum (the difference between the annihilation gamma rays in the opposite direction divided by the light speed c) is obtained.

[0016] Thus, the material degradation based on the principle of grasping the size distribution of the precipitate having a composition with a small affinity element by utilizing the feature that the positron flows in the direction of the smaller affinity due to the difference in the positron affinity. This is a degree measurement method.

FIG. 3 is a schematic view of a third embodiment, which will be described later, in which the parent phase is iron and the precipitate is copper. White represents iron atoms of the parent phase, and black represents copper atoms of the precipitate. is there. Table 1 shows the calculated values of the positron affinity of each element. From FIG. 3 and Table 1, positrons tend to gather in the direction of larger negative absolute values.

A second aspect of the present invention is characterized in that γ-rays generated when the positron annihilates with electrons are simultaneously measured by two detectors, and the simultaneous measurement is performed based on the principle of Doppler spread.

When a high-speed positron generated from RI or the like enters a metal, it decelerates in about 1 ps and becomes thermalized.
The thermalized positron diffuses and moves in the crystal over a distance of about 0.1 μm, annihilates one of many surrounding electrons with a lifetime of about 100 ps, and simultaneously emits 511 keV annihilation gamma rays in the opposite direction. (Relative angle: 180 degrees) Two are released.

At this time, the electron pair gravity center system and the observer system are compared, as shown in the principle diagram of the Doppler shift of the positron annihilation γ-ray shown in FIG. The energy of the annihilated gamma rays
511 keV + ΔE, 511 keV−ΔE, and the relative angle is also shifted from 180 degrees by Δθ. Also, since the positron has a positive charge,
Attempts to move away from the nucleus (positive ion) of the metal crystal.

Therefore, the positron moving around in the crystal is
Conduction electrons are the main annihilation partners, and positrons that have lost positive ions or reach the surface, such as vacancies, are captured and annihilated there. Atomic vacancies contain only conduction electrons in a dilute state, so that trapping has the effect of increasing the probability of disappearance with conduction electrons and the effect of prolonging the lifetime until disappearance.

As described above, the shift width ΔE of the annihilation γ-ray energy depends on the momentum of the electron pair, but the momentum of the bound electron is larger than that of the conduction electron, and becomes larger in the inner shell. Then, ΔE has a broad distribution.

On the other hand, conduction electrons have a small momentum and the momentum distribution is sharply cut off on the Fermi surface, so that ΔE has a sharp distribution. The proportion of the sharp component in the ΔE distribution depends on the proportion of conduction electrons among the annihilation partners, and increases as the atomic vacancy concentration increases the probability of disappearance with conduction electrons as described above.

However, since ΔE depends only on the annihilation γ-ray component of the electron pair momentum, which is a three-dimensional vector, and is observed as an integral of the other two-direction components, the electron pair momentum component is directly I can't get it.

In general, the ratio of a component having a smaller ΔE than an appropriate threshold value in a state where the integration of the two-direction components remains as it is is called an S parameter as an evaluation index. An evaluation method using this ΔE is the Doppler broadening (spreading) method. In addition, the positron annihilation measurement method includes Δ
There are methods for measuring θ and life.

The invention according to claim 3 is characterized in that the amount and the state of the elements in the material are evaluated based on the difference in the structure of the core electrons in the material. FIG. 8 shows the momentum axis component of electrons on the horizontal axis and the spectrum ratio between iron and the additional element on the vertical axis for nickel, manganese, copper, and the like as the additional elements in iron. The peak (shaded area) on the low momentum side indicates the point defect density. As the defect concentration increases, the peak increases accordingly. The curve on the peak high momentum side has a different shape for each added element. From this shape, the additional element can be identified. This depends on the structure of the inner shell electrons of the added element, and therefore, elements having similar inner shell structures have similar curves. The shape of the curve is a reference material, and the analysis is extremely easy if measured in advance.

A fourth aspect of the present invention is a material composed of a precipitate having a parent phase and an additional element as main constituent elements. The material is composed of two annihilation γ-rays generated during positron annihilation with respect to an axial component of electron-positron momentum. In the spectrum showing the count number, by taking the ratio of the spectrum of the material having only the matrix element and the spectrum of the material having the precipitate at the same energy,
It is characterized by grasping the behavior of the precipitate in the material.

A fifth aspect of the present invention is characterized in that the Doppler spread due to the annihilation of the positron or the evaluation of the point defect concentration by measuring the lifetime is also used. Doppler spread and lifetime measurements are commonly known techniques. What is intended by claim 5 is that it is important that these measurements can be performed at the same time as performing the main measurement. Doppler spread is 2
It is generally represented as the S parameter shown in the item.
The lifetime is derived as the time difference between the gamma ray of a specific energy generated directly from the positron source and the 511 keV gamma ray emitted when the positron annihilates. Both measurements are included in the measurement setup of the present invention.

The invention according to claim 6 is characterized in that the positron affinity of the material is larger in the negative absolute value of the added element than in the parent phase. The invention according to claim 7 is characterized in that the material is a reactor material, and the deterioration of the reactor material is measured. The invention according to claim 8 is characterized in that the reactor material is a pressure vessel or a Zircaloy fuel member.

According to the present invention, not all materials can be identified with additional elements. The applicable condition is positron affinity. In other words, it is important that the additive element is smaller than the parent phase (because the elements are all negative, the absolute value of the additional element is greater than that of the parent phase). The larger the difference, the easier the identification.

Therefore, the meaning of the notation that the upper and lower affinities are compatible means that the above conditions (the affinity of the added element is smaller than that of the parent phase and the difference is larger) are satisfied. This is not limited to metals.

The lithium drift type semiconductor detector utilizes the very high mobility of lithium ions in silicon or germanium, and exhibits good characteristics when lithium is in a solid solution. It is known that the properties are impaired when they are deposited.

Since the affinity of lithium is smaller than that of silicon or germanium, its operation characteristics (that is, the presence or absence of lithium precipitate) can be inspected by the present invention.

[0034] Zirconia ceramics are used as refractories, oxygen sensors, and mechanical structural materials. In many cases, yttrium and calcium oxides are added to zirconium oxide for structural stability. Since the affinity of yttrium and calcium is smaller than that of zirconium, the composition uniformity can be confirmed by the present invention.

According to a ninth aspect of the present invention, the materials are zirconium-tin alloy, iron alloy, iron-copper alloy, aluminum alloy, copper alloy, hafnium, tungsten alloy, molybdenum alloy, titanium alloy, niobium alloy, and vanadium alloy. , Ceramics or N-type semiconductor.

Zirconium-tin alloy is the main composition of zircaloy, which is a reactor fuel material. Since iron alloys have a relatively high affinity for iron, the present invention, which is a variety of alloys, can be applied. For example, iron-nickel alloys (nickel steel) are used as automobile parts, gun barrel materials, gears, and bolts. Iron-copper alloy is the main composition of reactor vessel pressure vessel steel. It is also used as an automobile part.

Aluminum alloys can be broadly classified into aluminum-copper alloys, aluminum-silicon alloys, and aluminum-magnesium alloys, but all of the added elements have a lower affinity than aluminum, so that the present invention can be applied. That is, it is possible to detect a change due to fatigue or hardening during use and embrittlement.

Aluminum-copper alloy is the most common casting alloy, and part of copper is sometimes replaced with zinc. In this case, too, it is detectable and used as die casting. The aluminum-copper-magnesium alloy is duralumin, but is used as a material for aircraft and gasoline engines. Aluminum-magnesium alloy is used for a camera body for die casting.

The copper-zinc alloy in the copper alloy is brass (brass), and when used as a spring material, there is an aging that the spring property is lost with time. Also, by adding iron, lead, and tin, they are used as gears, screws, marine machines, and condenser tubes. Since these are all deteriorated, the degree of the deterioration can be grasped by the present invention.

The copper-tin alloy is called bronze, and is used for copper wires and the like. Copper-aluminum alloy is called aluminum bronze and is used for plates, springs, screws and the like. Many of these have metal structure changes such as precipitation with time, and the deterioration measurement according to the present invention is effective.

Hafnium is used as a control rod for a nuclear reactor. This deteriorates due to a large amount of irradiation by neutrons, but the present invention can measure deterioration.
Tungsten alloys include those to which molybdenum and silver are added, and are used for electrical contacts and the like. In this case, the deterioration can be measured by the present invention. Molybdenum alloy is used as a heat-resistant material for aircraft. This is because the deterioration measurement for evaluating the soundness is important, and the present invention is effective.

Titanium alloys include manganese, chromium, aluminum, vanadium and the like as additional elements, and the measurement of aluminum is effective from the value of affinity. It is used for many materials such as aircraft.

Some niobium alloys include tin and zirconium as superconducting materials. These degradation measurements are possible with the present invention. The vanadium alloy can be measured by adding titanium, aluminum and iron, and its application to nuclear reactor materials is being studied. The ceramic and the N-type semiconductor are as described in claim 4.

According to a tenth aspect of the present invention, there is provided a material to be evaluated comprising a positron source, and two or more elements arranged near the positron source and receiving positrons emitted from the positron source and generating γ-rays. A first detector and a second detector which are arranged near the material to be evaluated and detect annihilation γ-rays at the time of annihilation of the generated γ-rays; and the first detector and the second detector A coincidence circuit connected to an output side of the detector and measuring a coincidence rate of the annihilation γ-rays.

According to the present invention, information on the distribution of precipitates can be obtained at the same time as the point defect concentration, by utilizing the fact that positrons are concentrated on precipitates having a lower positron affinity than the matrix elements. As a result, the mechanical strength can be inspected nondestructively.

[0046]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A first embodiment of a method and an apparatus for evaluating the degree of material deterioration due to positrons according to the present invention will be described with reference to FIG. FIG. 1 is a schematic diagram showing an apparatus layout for explaining a method of evaluating the degree of material deterioration according to the present invention and a first embodiment of the apparatus, and shows a simultaneous arrangement of annihilation gamma rays used in the present embodiment. It is a conceptual diagram of a measuring device for measuring a measured Doppler spread, and an explanatory diagram for measuring a general one-dimensional angular correlation and Doppler spread.

In FIG. 1, reference numeral 1 denotes a positron source, which receives a positron e ⁺ emitted from the positron source 1 and
A material composed of two or more kinds of elements that generate 1 and γ2, that is, a measurement sample (evaluation material) 2 is arranged near the positron source 1. In the vicinity of the measurement sample 2, a first semiconductor detector 3 for detecting the γ1 and a second semiconductor detector 4 for detecting the γ2 are arranged. The signal output sides of the first semiconductor detector 3 and the second semiconductor detector 4 are connected to a coincidence circuit 5.

The first semiconductor detector 3 and the second semiconductor detector 4 are fixedly installed at diagonal positions, and γ1
And γ2 are simultaneously counted. It is desirable that the first and second semiconductor detectors 3 and 4 have the same performance, but this is not an essential requirement. The positron source 1 is not particularly limited, but the distance from the measurement sample 2 is kept constant.

It is desirable that the first and second semiconductor detectors 3 and 4 have high efficiency in order to shorten the measurement time. Measurement sample 2 and first and second semiconductor detectors 3 and 4
Need not be equidistant, but must remain constant during the measurement. The coincidence circuit 5 measures the coincidence rate of the annihilation gamma rays. The device for evaluating (measuring) the degree of material deterioration configured in this way is very simple and does not require special settings.

Until now, positron annihilation measurement has taken advantage of the fact that positrons have a high probability of being annihilated with electrons near the location of point defects (atomic vacancies). The point defect concentration is measured by collecting γ-rays.

This is because the positron has a positive charge and tends to move away from the positive ions constituting the metal crystal. Therefore, conduction electrons are the main annihilation partner for positrons moving in the crystal. Positrons, such as atomic vacancies, that have reached the surface where the positive ions are missing or at the surface, are captured and annihilated.

In the angular correlation method shown in FIG. 1, the coincidence rate of the annihilation gamma rays γ1 and γ2 at the time of annihilation of the pair is measured, and the x-direction component of the total momentum of the annihilation positron and electron pair is obtained. this is,
The angle θ of the deviation from the exact opposite of γ1 and γ2, and the x-direction component Px of the total momentum P possessed by the annihilated positron and electron pair
And Px = mcθm is a relation between the static mass of electrons and c is the speed of light.

An apparatus based on this method requires an installation space having a length of 5 m or more and a strong positron source of several hundred MBq or more. On the other hand, there is a method in which one of the γ-rays is detected by a semiconductor detector having a high energy resolution, and the Doppler spread thereof is obtained, thereby obtaining a momentum component spectrum in the z direction. Although this method is inferior to the angular correlation method in resolution, it is one of the simplest measurement methods.

Next, the second embodiment of the present invention will be described with reference to FIGS.
An embodiment will be described. FIG. 2 shows the energy spectra of samples having different atomic vacancy concentrations by Doppler spread measurement. The measurement method is the same as that of FIG. 1 except for the second semiconductor detector 4. That is, by storing the energy spectrum of only the first semiconductor detector 3 while performing simultaneous measurement, a spectrum as shown in FIG. 2 can be obtained.

FIG. 2 shows an example of a spectrum obtained by the Doppler spread method. This is a spectrum of a void which is an aggregate of atomic vacancies in molybdenum and a complete crystal without vacancies. Further, for simplicity, the ratio of the area of the portion A to the entire area is often quantified by a number called an S parameter. It can be seen that the S parameter is larger in the void than in the perfect crystal. In this method, there is a method of evaluating the point defect amount by quantifying the spread of the momentum.

Therefore, the point defect amount can be evaluated, but other parameters cannot be known. Point defects flow into crystal grain boundaries, dislocations, precipitates, etc., and disappear or are newly generated, but their quantification is difficult even at the laboratory level. However, many suggest a correlation between material degradation and precipitate distribution.

In the case of a perfect crystal having no defect, the spectrum is broad. On the other hand, in the sample having voids, which is a group of point defects, the peak at the center is clear. That is, the clearer the peak near the center, the higher the point defect concentration.

There is an S parameter as a quantification of this. This is defined by the ratio of the area of the central portion A to the entire area. Therefore, the larger the S parameter is, the higher the point defect density is.

Next, a third embodiment of the present invention will be described with reference to FIGS. FIG. 3 is a schematic diagram showing a state in which positrons gather toward copper with low affinity, assuming that iron atoms in the mother phase are white and copper atoms as precipitates are black in the third embodiment according to the present invention. FIG.

FIG. 4 is a momentum spectrum diagram of a sample obtained by aging a 1.0% iron alloy at 550 ° C. for 2 hours and a sample of pure iron and pure copper in the third embodiment according to the present invention. The difference between the energy of γ1 and γ2 shown in FIG. 1, that is, the difference between the energies of annihilation γ-rays in the opposite direction is divided by the light speed c, and the vertical axis indicates the count number.

FIG. 5 shows a third embodiment according to the present invention, in which an iron-1.0% copper alloy is hardened (b), aged for 0.1 hour (c), and aged for 0.2 hour. (D), aged for 2 hours (e), and a spectrum of pure copper (a) divided by a spectrum of pure iron as a reference, respectively.

As the aging time becomes longer, ie, b,
The peak positions are higher in the order of c, d, and e. Then, pure copper a has the highest peak. It has also been found that as the aging time becomes longer, copper precipitates appear and the size becomes coarser.

Next, a fourth embodiment of the present invention will be described with reference to FIG. FIG. 6 shows the results of aging the iron-1.0% copper alloy for 10 hours (f), aging for 100 hours (g), aging for 312 hours (h), and pure copper (a and 3) divided by the spectrum of pure iron. As the aging time increases, the size of the copper precipitate becomes coarser and f,
The peak position becomes lower in the order of g and h.

Next, FIG. 5 and FIG. 6 show a fifth embodiment of the present invention.
An embodiment will be described. From FIG. 5 and FIG.
The copper alloy aged for 10 hours (referred to as f) shows a momentum distribution fairly close to that of pure copper, and shows a peak height as an aging material. Inverted from here and aged for 100 hours (g
) Has a lower peak. Focusing only on the high momentum component, the 0.2 hour aged material (d curve) and the 100 hour aged material (g curve) are very similar.

However, comparing the low momentum components, FIG.
In FIG. 6, the slope is smaller than 1 and the slope of decrease is small, whereas in FIG. from now on,
It can be distinguished whether the peak is rising or falling. A look at the low and high momentum components reveals the size of the precipitate.

Next, FIG. 5 and FIG. 6 show a sixth embodiment of the present invention.
An embodiment will be described. In the present embodiment, the material to be evaluated is applied to the material of the reactor pressure vessel, and the material of the reactor pressure vessel is an iron-copper alloy. According to this embodiment, the third to fifth embodiments can be applied, whereby the degree of deterioration of the material can be evaluated.

Next, a seventh embodiment of the present invention will be described with reference to Table 1. Table 1 shows the calculated values of the positron affinity of each published element. According to Table 1, the elements having a large positron affinity are used as the mother phase, the small elements are used as the additional elements, and all of the compositions in which the additional elements are precipitated are shown. 5 and 6 can be obtained.

[0068]

[Table 1]

Next, an eighth embodiment of the present invention will be described with reference to Table 1. In the present embodiment, the material to be evaluated is applied to a nuclear reactor fuel member. Zircaloy, which is a nuclear reactor fuel member, is a zirconium-tin alloy, and the upper and lower positron affinity is suitable. This makes it possible to evaluate the degree of deterioration of Zircaloy.

According to Table 1, deterioration of a semiconductor can be evaluated by measuring an element having a large positron affinity, for example, phosphorus or lithium in silicon. Also, according to Table 1,
By measuring an element having a large positron affinity, for example, titanium in zirconia, deterioration of the ceramic can be evaluated.

[0071]

According to the present invention, heat during use of an inorganic material,
The point defect concentration and precipitate size distribution due to external factors such as stress and radiation can be evaluated nondestructively. Therefore, simple and low-cost evaluation can be performed in a field where the soundness of a material has been evaluated by a destructive test such as a mechanical test or a microstructure test.

[Brief description of the drawings]

FIG. 1 is an apparatus layout diagram schematically illustrating a first embodiment of a method for evaluating the degree of material deterioration and the apparatus according to the present invention.

FIG. 2 is an energy spectrum diagram of samples having different atomic vacancy concentrations according to a second embodiment of the method of the present invention.

FIG. 3A is a schematic diagram of a third embodiment of the method of the present invention, and FIG. 3B is an energy distribution diagram of FIG.

FIG. 4 is a momentum distribution diagram obtained by similarly aging a 1.0% iron alloy at 550 ° C. for 2 hours.

FIG. 5 is a spectrum diagram showing a ratio of pure iron to a 1.0% copper alloy which is hardened and aged for each time.

FIG. 6 is a spectrum diagram showing a ratio of iron-1.0% copper alloy to pure iron in the fourth and fifth embodiments of the present invention.

FIG. 7 shows a positron annihilation γ for explaining the invention of claim 2;
FIG. 4 is a principle diagram showing Doppler shift of a line compared between an electron pair centroid system and an observer system.

FIG. 8 is a spectrum diagram showing the momentum of an additional element in iron in terms of the ratio to pure iron for explaining the invention of claim 3;

[Explanation of symbols]

1: positron source, 2: sample for measurement (material to be evaluated), 3
... first semiconductor detector, 4 ... second semiconductor detector, 5 ...
Coincidence circuit.

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Masayuki Hasegawa 2-1-1 Katahira, Aoba-ku, Sendai-shi, Miyagi Pref. Metals Research Laboratory, Tohoku University (72) Inventor Kosuke Nagai Narita, Oarai-cho, Higashiibaraki-gun, Ibaraki Tohoku University Metal 2G001 AA08 CA02 DA02 DA06 EA03 FA01 GA01 KA03 KA20 LA02 LA06 LA20 NA03 NA07 NA10 NA11 NA12 NA15 NA17 2G075 AA01 BA16 CA04 CA38 DA15 EA03 EA07 FA05 FA18 FB10 FC20 GA19

Claims (10)

[Claims] 1. A method for evaluating a degree of deterioration of a material composed of two or more elements by radiating a positron from a positron source to evaluate a degree of deterioration of the material. A method for evaluating the degree of material deterioration, characterized in that when positrons accumulate in an atomic aggregate of an additional element from a phase element, the type of the aggregate of the additional element is determined by utilizing the fact that the momentum distribution differs depending on the element. 2. The material according to claim 1, wherein the gamma rays generated when the positron annihilates with the electrons are simultaneously measured by two detectors, and the simultaneous measurement is performed based on the principle of Doppler broadening. How to evaluate the degree of deterioration. 3. The method for evaluating the degree of material deterioration according to claim 2, wherein the amount and the state of the elements in the material are evaluated based on the difference in the structure of the core electrons in the material. 4. The material comprises a parent phase and a precipitate containing an additional element as a main constituent element, and indicates a count number with respect to an axial component of electron-positron momentum of two annihilation gamma rays generated at the time of positron annihilation. By taking the ratio of the spectrum of the material having the precipitate and the spectrum of the material having the precipitates at the same energy,
4. The method according to claim 1, wherein the behavior of the precipitate in the material is grasped. 5. The method for evaluating the degree of material deterioration according to claim 1, wherein evaluation of the point defect concentration by Doppler spread due to annihilation of the positron or lifetime measurement is also used. 6. The method according to claim 1, wherein the positron affinity of the material is larger in a negative absolute value of the additive element than in the parent phase. 7. The reactor according to claim 1, wherein the material is a reactor material, and the deterioration of the reactor material is measured.
The described method for evaluating the degree of material deterioration. 8. The method according to claim 7, wherein the reactor material is a pressure vessel or a fuel member made of Zircaloy. 9. The materials include zirconium-tin alloy, iron alloy, iron-copper alloy, aluminum alloy, copper alloy, hafnium, tungsten alloy, molybdenum alloy,
The method for evaluating the degree of material deterioration according to any one of claims 1 to 5, wherein the method comprises one selected from a titanium alloy, a niobium alloy, a vanadium alloy, a ceramic, and an N-type semiconductor. 10. A positron source, and a γ-ray source arranged in the vicinity of the positron source for receiving positrons emitted from the positron source.
A material to be evaluated composed of two or more types of elements that generate rays, a first detector arranged near the material to be evaluated, and a detector for detecting annihilation γ-rays at the time of annihilation of the generated γ-rays; 2
And a coincidence circuit connected to the outputs of the first and second detectors for measuring the coincidence rate of the annihilation γ-rays. Evaluation device.