JP2995298B1 - Deformation measurement method and grid sheet for deformation measurement - Google Patents

Abstract

An object of the present invention is to provide a deformation measuring method capable of investigating the influence of the concentration of strain around a minute inclusion or a notch and the presence of the notch on the deformation of the entire material. SOLUTION: A model grid fabricated on a sample is irradiated with particle beams at two or more types of line densities, and two or more types of moire fringes are formed depending on a difference in the amount of secondary electrons generated, and the amount of deformation of the sample is measured. Deformation measurement method characterized by forming a model grid on a thin film of plastic, polymer, vinyl, rubber or metal and attaching it to a sample or structure Provide a grid sheet.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a deformation measuring method and a deformation measuring sheet. More specifically, the invention of this application relates to a deformation measurement method useful for measuring the deformation amount of a material at a high temperature as well as a normal temperature, elucidating a damage generation process, and further monitoring a reliability of a structure, and a deformation measurement used for the method It relates to a sheet for use.

[0002]

2. Description of the Related Art Material damage often occurs at a stress concentration part around a grain boundary triple point or an inclusion, and it is important to measure the amount of deformation of these minute parts to elucidate the process of material damage generation. Is an important issue. On the other hand,
The moiré method is known as one of the methods for measuring the amount of deformation of a material. In this moiré method, a regular geometric pattern (model grid) is drawn on a sample, and another regular pattern (master grid) is superimposed on the sample. The moire method is formed by overlapping portions and non-overlapping portions. It is characterized in that the amount of deformation is obtained from the light and shade stripes (moire stripes).

However, in the conventional moire method,
In terms of grating fabrication technology and moire fringe fabrication technology in which two grids are superimposed, it is large enough to be applied to observation or measurement of non-uniform deformation in a small area, which enables observation and analysis of material damage generation process. There is a problem that moire fringes having a linear density cannot be obtained. In order to solve these problems, a multiplication method using interference of diffracted light and a laser moiré interference method capable of obtaining fine moiré fringes using interference of laser light have been developed. And a method of obtaining moiré fringes using pixels of a CCD camera as a master grid, and a method of obtaining moiré fringes by Fourier transforming the brightness of a model grid. However, in the case of these methods, since the entire surface of the sample is covered with resin, observation of the sample surface is impossible, and complicated devices and image processing devices for interfering laser light on the sample are required. Further, there is a problem that it is difficult to make the distance between these model grids smaller than the wavelength of light.

An electron beam moiré method (Japanese Patent No. 187559) has been further developed to solve the problem of the moiré method.
7). In this electron beam moiré method, a particle grid that is scanned in a parallel lattice shape is used as a master grid of the moiré method, and a grid made by evaporating a substance having a different amount of secondary electrons from the sample on the sample surface is used as a model grid. Used. The difference in the amount of secondary electrons generated when the particle beam is irradiated on the sample surface causes a difference in brightness and darkness, thereby forming moire fringes. In this method, since a scanning electron microscope or a focused ion beam microscope capable of observing a minute area is used, there is an advantage that the observation area and the width of the master grid (particle beam scanning width) can be freely controlled.

However, in spite of such improvements, even in the case of the electron beam moiré method, the distance between the model grids cannot be changed, and the measurement accuracy cannot exceed the distance between the model grids. There is a problem that the accuracy is the same everywhere on the model grid. In order to solve such a problem, it is considered that a finer model grid should be used. However, in practice, it has been difficult to apply the fine grid to deformation measurement of a metal material. This is because when metal materials are deformed, the direction of deformation differs for each crystal grain because most metal materials are polycrystalline, causing phenomena such as slipping at crystal grain boundaries and rotation of crystal grains. This is because these phenomena often make it impossible to measure the amount of deformation due to moiré fringes using only a fine model grid. For example, 1 μm
When a grain boundary slip occurs, there is no problem with a model grid having a width of 1 μm and an interval of 2 to 3 μm.
When using a model grid with m width and 1 μm spacing,
The gap between the model grids and the amount of displacement match, making it difficult to measure the slip amount. In order to avoid this, if a model grid with a wide width of micron size and a large space is used, it is impossible to measure the state of deformation around inclusions of about 1 μm to several μm and the state of deformation near the grain boundary triple point. The problem of being impossible arises.

Therefore, the invention of this application solves the above-mentioned drawbacks of the prior art, and accurately examines the influence of the concentration of strain around small inclusions or notches and the presence of notches on the deformation of the entire material. It is an object of the present invention to provide a new means for measuring deformation that can be evaluated with high accuracy.

[0007]

In order to solve the above-mentioned problems, the present application firstly proposes, on a sample surface, two or more linear densities of substances different in the amount of secondary electrons generated from the sample. It is characterized by irradiating the model grid arranged in the above with particle beams at two or more types of line densities, forming two or more types of moiré fringes due to the difference in the amount of secondary electrons generated, and measuring the deformation amount of the sample. To provide a deformation measurement method. In addition, this application
A method of measuring the amount of deformation by arranging a model grid on the surface of the conductive material, and arranging a model grid on the surface of the conductive material, and forming a model grid on a thin film, Next, a deformation measurement method for measuring the amount of deformation by disposing the thin film on which the model grid is formed on the sample surface is provided. Fourth, the present application relates to a model grid of the method according to any one of the first to third aspects, wherein
Fifthly, a model grid characterized by being disposed at two or more types of line densities by lithography or laser interferometry of electron beam, light or X-ray, on a thin film disposed on the sample surface, , A grid sheet having a model grid formed thereon, wherein the thin film is formed of resin, rubber, metal, or a composite thereof.

[0008]

BEST MODE FOR CARRYING OUT THE INVENTION The invention of this application has the features as described above, and the embodiments will be described below. First, the method for measuring the amount of deformation according to the present invention is based on the following requirements. <I> A substance having a different secondary electron generation amount from the sample is arranged on the surface of the sample at two or more linear densities to form a model grid. <II> Two or more kinds of particle beams are formed on the model grid. Irradiation is performed at a linear density, and <III> two or more types of moire fringes are formed due to the difference in the amount of secondary electrons generated, and the amount of deformation of the sample is measured.

[0009] In this requirement, the sample may be various kinds of metal-based substances such as metals, alloys, and steels, and furthermore, any material such as plastics and ceramics as long as the surface has conductivity. May be. The sample surface on which the model grid is disposed may be the surface of the sample substrate itself, or a surface formed of a substance formed by vapor deposition or the like, for example, a vapor-deposited film of a conductive substance. It may be a surface composed of an adhesive thin film such as a sheet, a film, or a foil arranged by sticking or the like. In the case of the latter thin film, the thin film naturally reflects the surface shape of the sample substrate and its deformation.

On such a sample surface, that is, the sample surface including the above-mentioned coating film and adhesive thin film, a model grid is provided with two or more kinds of linear densities as described above. The material constituting the grid in this case is a material having a different secondary electron generation amount from the sample surface. In this case, the model grids of two or more types of linear densities may be different types of materials or different types of materials.

The material constituting such a model grid may be various metals, alloys and the like.
t, Rh, Pd, Au, Ag, Ir), chromium (C
r), zirconium (Zr), titanium (Ti), tantalum (Ta), niobium (Nb), nickel (Ni), cobalt (Co), copper (Cu) and the like. Model grid materials are more suitably heat resistant (high melting point)
It is a conductive substance.

When a model grid is formed on such a thin film by using such a material, the thin film may be made of various resins,
That is, it may be made of various materials such as plastic, polymer, vinyl and rubber, or a material such as metal. What formed the model grid on the thin film,
It will be used as a grid sheet in the method of the present invention.

Regarding the formation of the model grid, in the present invention, as described above, vapor deposition, electron beam,
It is carried out as a method of arranging at two or more kinds of line densities by light or X-ray lithography or laser interference. Of course, other methods may be used. For example, a model grid manufacturing process according to the present invention can be exemplified below.

1) The sample is polished to a mirror surface. 2) A substance having heat resistance is deposited on the sample. However, this process may be omitted. 3) Apply an electron beam resist, a photoresist, or an X-ray resist on the sample.

4) An electron beam or interference caused on the sample 2
The laser beam of the light beam is scanned in an arbitrary geometric pattern.
Alternatively, a mask having an arbitrary geometric pattern is placed on the sample and irradiated with light or X-rays. 5) Using a solvent, remove any one of the electron beam resist, the photoresist, and the portion of the X-ray resist irradiated with the electron beam, laser, light or X-ray. Alternatively, the irradiated portion is left.

6) A sample material or a material having a different secondary electron generation amount from the vapor deposition material of the above 2) is vapor deposited. 7) Remove any one of the electron beam resist, the photoresist and the X-ray resist with a solvent to complete the first model grid. 8) A position for producing a finer model grid is determined, and the processes of 3) to 6) are repeated.

9) Either the electron beam resist, the photoresist or the X-ray resist is removed with a solvent to complete a composite model grid. In general, it is considered that the grid has a line density of (A) a line spacing of 5 to 15 μm and (B) a line spacing of 0.5 to 1.5 μm. The line width and thickness of the grid are not particularly limited. However, considering the object of measurement of the amount of deformation according to the present invention, generally, the line width is 0.1 to 3 μm, and the thickness is 0.1 μm.
1 to 1 μm is appropriate.

When a film is previously formed on the surface of the sample by vapor deposition or the like, the thickness is generally 0.1%.
To 1 μm, and when a thin film is used as the grid sheet, the thickness of the thin film is 0.5 to 3 μm.
μm is appropriate. Further, in the case of forming a vapor-deposited film, it is preferable to make the film conductive and heat-resistant in order to avoid electrification accompanying particle beam irradiation and oxidation during high-temperature use. Similarly, the reason why the material constituting the grid is preferably heat-resistant is to avoid aggregation due to oxidation and diffusion during use at high temperatures.

In the deformation measuring method of the present invention using the above-described model grid or the like, Moire fringes having different line densities are generated due to the difference in the amount of secondary electrons generated by irradiating the model grid with particle beams. It appears as moire fringes with different contrasts (different brightness). The amount of deformation can be determined by measuring the interval, angle and displacement of the moire fringes.

The particle beam may be various ions including electrons. The present invention further develops the electron beam moiré method capable of measuring the amount of deformation in a minute area by the above-described configuration, and uses a composite model grid to provide an overall amount of deformation and an amount of deformation of a minute portion. Enable measurement. For example, the influence of the concentration of strain at the notch tip and the presence of the notch on the deformation of the entire material can be investigated. In addition, depending on the substance to be deposited on the sample (in the case of a substance having a high melting point), a model grid in which deterioration of the model grid due to diffusion or oxidation at a high temperature is small can be manufactured.

According to the present invention, it is possible to simultaneously measure the state of the strain at the crack tip and the effect of the crack generation on the entire structure, and obtain information necessary for safety design of an aircraft or the like. Therefore, a detailed description will be given according to the following embodiments. Of course, the present invention is not limited by the following examples.

[0022]

EXAMPLE 1 After depositing Zr on 304 stainless steel, an electron beam resist is applied on the sample. The sample was scanned with an electron beam at intervals of 10 μm, the irradiated portion of the electron beam resist was removed with a solvent, Pt was evaporated, and the electron beam resist 1 was evaporated with a solvent.
A model grid of Pt at intervals of 0 μm is completed. A position where a finer model grid is produced is determined on the model grid, and an electron beam resist is applied on the sample. An electron beam is scanned at an interval of 1 μm, the irradiated portion of the electron beam resist is removed with a solvent, Pt is deposited, and the electron beam resist is removed with a solvent, thereby completing a Pt model grid at an interval of 1 μm.

FIG. 1 of the accompanying drawings shows that Zr is deposited on 304 stainless steel and Pt is deposited on the stainless steel to form a gap of 10 μm.
3 is a scanning electron micrograph of a composite model grid of m and 1 μm. Next, an electron beam of 9 μm was applied to the coarse model grid in a wide area of the model grid shown in FIG.
Scanning was performed at an interval of m with a tilt of 1 degree. The result is shown in FIG.

FIG. 2 of the accompanying drawings is a scanning electron micrograph of electron beam moiré fringes observed when a wide area of the composite model grid of FIG. 1 is irradiated with an electron beam inclined at 1 degree at intervals of 9 μm. . Further, an electron beam is applied to an area where a fine model grid is located at the center of the composite model grid.
Irradiation was performed at 9 μm intervals. The result is shown in FIG.

FIG. 3 of the attached drawings shows a scanning type electron beam moire fringe observed when an area of a fine model grid at the center of the composite model grid is irradiated with electron beams at 0.9 μm intervals. It is a microscope picture. Example 2 After depositing Cr on 304 stainless steel, an electron beam resist is applied on the sample. The sample is scanned with an electron beam at intervals of 10 μm, the irradiated portion of the electron beam resist is removed with a solvent, Zr is vapor-deposited, and the electron beam resist is removed with a solvent, thereby completing a Zr model grid at a 10 μm interval. . A position where a finer model grid is produced is determined on the model grid, and an electron beam resist is applied on the sample. An electron beam is scanned at an interval of 1 μm, the irradiated portion of the electron beam resist is removed with a solvent, Pt is deposited, and the electron beam resist is removed with a solvent, thereby completing a Pt model grid at an interval of 1 μm.

FIG. 4 of the accompanying drawings is a schematic view of a composite model grid of a 1 μm model grid in which Cr is deposited on 304 stainless steel, Zr is deposited to form a model grid with a spacing of 10 μm, and then platinum is deposited. It is. FIG.
When a 9 μm-spaced electron beam was scanned over the entire model grid shown in FIG. 5, slightly bright moire fringes at a 99 μm-space were observed. Further, when an electron beam was scanned at an interval of 0.9 μm over a certain portion of the model grid with fine Pt, brightest moire fringes at an interval of 9.9 μm were observed. Example 3 After depositing Zr on 304 stainless steel, an electron beam resist is applied on the sample. The sample is scanned with an electron beam at intervals of 10 μm, the irradiated portion of the electron beam resist is removed with a solvent, Cr is deposited, and the electron beam resist is removed with a solvent, and a model grid of Cr at intervals of 10 μm is completed. . A position where a finer model grid is produced is determined on the model grid, and an electron beam resist is applied on the sample. An electron beam is scanned at an interval of 1 μm, the irradiated portion of the electron beam resist is removed with a solvent, Pt is deposited, and the electron beam resist is removed with a solvent, thereby completing a Pt model grid at an interval of 1 μm.

FIG. 5 of the accompanying drawings is a schematic diagram of a composite model grid of a 1 μm model grid in which Zr is deposited on 304 stainless steel, a Cr is deposited to form a model grid with a spacing of 10 μm, and then platinum is deposited. It is. FIG.
When an electron beam at 9 μm intervals was scanned over the entire model grid shown in FIG. 7, dark moire fringes at 99 μm intervals were observed.
Further, when an electron beam was scanned at an interval of 0.9 μm over a portion of the model grid with fine Pt, bright moire fringes at an interval of 9.9 μm were observed.

[0028]

As described in detail above, according to the present invention, it is possible to investigate the concentration of strain around small inclusions and the tip of a notch, and the effect of inclusions and notches on the deformation of the entire material. This provides a method for simultaneously measuring the state of strain around the inclusion or the tip of the crack and the effect of the crack on the entire structure.

As a result, it is possible to easily obtain information necessary for the safety design of a vehicle or an aircraft, thereby facilitating the reduction of the weight of a high-speed transportation vehicle or an aircraft, and to improve safety. Considered large.

[Brief description of the drawings]

FIG. 1 is a scanning electron micrograph of a composite model grid with a spacing of 10 μm and 1 μm produced by depositing Zr on Pt 304 and depositing Pt.

FIG. 2 is a scanning electron micrograph of electron beam moiré fringes observed when a large area of the composite model grid of FIG. 1 is irradiated at an interval of 9 μm with an electron beam inclined at one degree.

FIG. 3 is a scanning electron micrograph of electron beam moiré fringes observed when an electron beam is irradiated at an interval of 0.9 μm onto a region of a fine model grid at the center of the composite model grid.

FIG. 4 is a schematic diagram of a composite model grid of a 1 μm model grid in which Cr is deposited on 304 stainless steel, Zr is deposited to form a model grid with an interval of 10 μm, and then platinum is deposited.

FIG. 5 is a schematic view of a composite model grid of a 1 μm model grid in which Zr is vapor-deposited on 304 stainless steel, a Cr is vapor-deposited to produce a model grid with a spacing of 10 μm, and platinum is vapor-deposited.

──────────────────────────────────────────────────続 き Continued on the front page (58) Field surveyed (Int. Cl. ⁶ , DB name) G01B 15/00-15/08 G01N 23/00-23/227

Claims (5)

(57) [Claims] 1. A method of irradiating a particle grid with two or more linear densities to a model grid in which a substance having a different secondary electron generation amount from a specimen is arranged at two or more linear densities on the surface of the specimen. A deformation measurement method characterized in that two or more types of moire fringes due to differences in the amount of generated electrons are formed and the amount of deformation of the sample is measured. 2. The deformation measuring method according to claim 1, wherein the surface of the sample is formed of a conductive material, and a model grid is disposed on the surface of the conductive material to measure a deformation amount. 3. The deformation measuring method according to claim 1, wherein a model grid is formed on the thin film, and then the thin film on which the model grid is formed is arranged on a sample surface to measure a deformation amount. 4. A model grid according to claim 1, wherein the model grid is formed by vapor deposition and lithography or laser interferometry of an electron beam, light or X-ray at two or more types of line densities. A model grid, which is provided. 5. The method according to claim 4, wherein the thin film is disposed on a sample surface.
Wherein the thin film is formed of resin, rubber, metal, or a composite thereof.