JPH05322720A - Dissolving method for specimen of inclusion - Google Patents

Abstract

PURPOSE:To allow substantially all inclusions in a metal specimen to come up to the specimen surface by measuring the temp. of the specimen, and controlling an electron beam so that it is maintained at a predetermined melt temp. for a specified period of time. CONSTITUTION:Specimens 6a, 6b... are placed in recesses 5a, 5b... on a heath 3 provided in a vacuum vessel 2, and an electron beam EB is emitted by an electron gun 9. The beam EB is deflected 180deg. and cast onto the specimen 6a to heat it. A controller 12 reads the period information and temp. stored in a memory 13 in accordance with the material of the specimen 6a or inclusions, and a power supply 10 is accordingly controlled, and thus the output of the electron gun 9 is controlled. A temp. sensor 11 measures the temp. of the specimen at all times. In this manner heating is performed, and the inclusions are allowed to come up to the surface, and then the controller 12 controls a power supply 8 and drives a motor 7 to rotate a rotary shaft 4, and the specimen 6b accommodated in the next recess 5b on the herth 3 is placed in the irradiating position with electron beam EB.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION The present invention, as a pretreatment for analyzing a small amount of inclusions contained in a metal sample, irradiates the sample with an electron beam to melt the inclusions and floats the inclusions on the sample surface. And a method for dissolving inclusion samples.

[0002]

2. Description of the Related Art In order to qualitatively and quantitatively analyze a small amount of inclusions (mainly metal oxides, nitrides, etc.) contained in a metal, the sample is irradiated with an electron beam and dissolved before analysis. It has been practiced to levitate the inclusions on the surface of the sample, then stop the irradiation of the sample with the electron beam, and cool the sample to prepare a sample for inclusion analysis. The sample in which the inclusions are floated on the surface and solidified is subjected to qualitative and quantitative analysis with, for example, an EPMA (electron rope microanalyzer) or a scanning electron microscope.

When melting a sample, a vacuum is used.
Place a hearth in the vessel and place a metal sample in the hearth.
The sample is irradiated with an electron beam.
When irradiating with this electron beam, a small amount is
The inclusions contained in the sample are almost the same without changing the shape of the inclusions.
It is necessary to raise almost everything and therefore
Strictly control the irradiation electron beam output
I have to. The graph shown in FIG.
Is the control curve of the electron beam output, where the horizontal axis is
Time, the vertical axis is the electron beam output. Clear from this graph
As you can see, the output of the electron beam is P₁And P_Two2 steps
It has been changed to the floor. In other words, the sample₁E-bi
Output by T_TwoElectron beam after preheating for a period of
Output P _TwoTo dissolve the sample during the T4 period and rapidly
I try not to heat it.

Even when the preheating state is changed to the melting state, if the electron beam output is suddenly raised, a bumping phenomenon may occur and the sample may scatter.
_As shown in ₃ , it is gradually increased. Further, the value of the electron beam output P ₂ that dissolves the sample is set to a position where evaporation of the sample does not occur, so that the inclusions are efficiently levitated. At this time, if the dissolution period T ₄ becomes long, the floating inclusions are melted, so it is necessary to stop the dissolution before the inclusions are melted. Even against the stop of the sample dissolution, the stops irradiation of the instantaneous electron beam, the temperature of the sample is rapidly reduced, whereby there is a risk that the shape collapses inclusions cracks surfaced occurred, the period of T ₅ is , The electron beam output is gradually weakened and turned off. When the sample is irradiated with the electron beam output P ₁ instantaneously during the preheating of the sample, a current may flow in the sample, which may move the sample.
As indicated by the start-up period T ₁ , the output of the electron beam is gradually increased.

[0005]

By the way, the amount of heat that escapes from the sample through the hearth or by radiation,
The temperature of the sample rises until it balances with the amount of heat generated by the electron beam. Therefore, the melting temperature of the sample varies depending on the weight and size of the sample, the contact state between the hearth and the sample, and it is very difficult to control the melting temperature of the sample by controlling the output of the electron beam depending on the time described above. Become. If the minute inclusions are substances such as alumina (Al ₂ O ₃ ) that have a high melting point and are less likely to be redissolved or condensed by heat, the inclusions will be relatively small even if conditions such as the size of the sample change to some extent. Floating on the sample surface with accurate amount and original shape,
As a result, accurate observation and analysis can be performed. However, when MgO or SiO ₂ having a melting point relatively close to the melting point of the molten metal is an inclusion, the inclusion does not come up due to a slight difference in melting conditions, or even if the inclusion comes up, In many cases, it condenses quickly and the original shape cannot be confirmed.

The present invention has been made in view of the above circumstances, and an object thereof is to realize a method for dissolving inclusion samples in which almost all the inclusions in a metal sample can be floated on the surface of the sample. is there.

[0007]

The method for dissolving inclusion samples according to the present invention is directed to irradiating an electron beam to a sample on a hearth provided in a vacuum vessel to dissolve the sample, and to include inclusions contained in the sample. In the method of dissolving an inclusion sample, which floats on the surface of the sample, when melting the sample, the temperature of the sample is measured, and the sample temperature is maintained at a predetermined melting temperature for a predetermined period, based on the measured temperature. It is characterized in that the electron beam with which the sample is irradiated is controlled.

[0008]

The inclusion sample melting method according to the present invention measures the temperature of the sample, and irradiates the sample on the basis of the measured temperature so that the sample temperature is maintained at a predetermined melting temperature for a predetermined period. To control.

[0009]

Embodiments of the present invention will now be described in detail with reference to the drawings. FIG. 2 shows an example of a dissolution apparatus for carrying out the method for dissolving inclusion samples according to the present invention, in which 1 is a main body of the apparatus. A vacuum vessel 2 is detachably mounted on the upper surface of the main body 1 in an airtight manner, and the inside of the vacuum vessel is evacuated by a vacuum pump (not shown).
In the vacuum vessel 2, a circular copper hearth is provided. The hearth 3 is rotatably held by a rotary shaft 4 that penetrates the main body 1 in an airtight manner, and a large number of recesses 5a, 5b, ... Are centered on the rotation center on the upper surface of the hearth 3. It is formed at equal intervals on the circumference.
The samples 6a, 6b, ... Are accommodated in the respective recesses. Reference numeral 7 is a motor for rotating the rotary shaft 4, and 8 is a drive power source thereof. The hearth 3 is water-cooled (not shown).

Reference numeral 9 denotes an electron gun provided in the vicinity of the hearth. An electron beam EB generated from the electron gun 9 is deflected by about 180 ° by a deflecting means (not shown) and is set at a melting position on the hearth 3. Irradiate. 10 is a power source of this electron gun. The electron gun 9 includes a deflection system (not shown) for two-dimensionally scanning the electron beam on the sample.

Reference numeral 11 denotes a temperature sensor placed above the hearth 3 in the vacuum vessel 2 to measure the temperature of the sample 6 at the position irradiated with the electron beam. A controller 12 is supplied with a temperature signal measured by the temperature sensor 11. The controller 12 controls the motor power source 8 and the electron gun power source 9. 13 is a controller 12
The memory 13 stores the optimum melting temperature for each material of the sample and the inclusions. The operation in such a configuration is as follows.

First, the samples 6a, 6b, ... Are placed in the respective recesses 5a, 5b ,.
Then, the inside of the vacuum vessel 2 is evacuated and maintained at an appropriate degree of vacuum. Then, the electron gun power supply 10 is turned on, and the electron beam EB is emitted from the electron gun 9. Electron beam E
B is deflected by 180 ° and is irradiated on the sample 6a in the recess 5a to heat the sample. Now, FIG. 3 is a graph showing the relationship between temperature and time of the sample controlled by the method according to the present invention. In the first period T ₁ , the temperature of the sample is gradually increased. The reason for gradually raising the temperature is to prevent the sample from moving as described above. Then, when the temperature reaches t ₁ , the sample is maintained at this temperature t ₁ for a certain period T ₂ . This period T ₂ is the sample preheating period.

When the preheating period T ₂ ends, the sample temperature is gradually increased again during the period T ₃ by increasing the output of the electron beam. The reason for this is also described above, but when the electron beam output is rapidly raised and the sample temperature is rapidly raised, the bumping phenomenon occurs and the sample is scattered. When the sample temperature reaches t ₂ , the sample is maintained at the temperature t ₂ for the period T ₄ . This period T ₄ is the dissolution period, and the sample is dissolved in a short time of several seconds. After the melting period T ₄ , the electron beam output was gradually decreased to lower the sample temperature, and when the sample temperature became t ₃ , the sample temperature was this value t.
_It is fixed at ₃ . This period T ₆ is a molten state holding period, and the temperature t ₃ is a temperature at which the metal sample can be held in a molten state between the melting temperature t ₂ and the preheating temperature t ₁ . In addition, this temperature is set to a value at which inclusions floating on the surface of the sample are redissolved and condensed, the shape of the inclusions is not destroyed, and the inclusions are not remelted in hot water. During such a dissolution state holding period T ₆ , most of the inclusions inside the sample float to the sample surface. During T ₇ after the end of this period T ₆ , the electron beam output is gradually reduced to lower the sample temperature, and after the end of T ₇ , irradiation of the electron beam to the sample is stopped.

Now for the particular sample of FIG.
When performing control, the controller 12 first determines the sample
It is stored in the memory 13 according to the material of the inclusions
Each temperature (t₁, T_Two, T_Three) And period (T₁~ T₇)
Read information. Then, depending on this period,
The source 10 is controlled to control the output of the electron gun.
The temperature sensor 11 constantly measures the sample temperature,
Temperature is t₁When the sample temperature becomes T_TwoBetween t₁
So that the controller 11 maintains the electron gun power source 1
Control 0. Period T_TwoAfter a lapse of time, the power supply 10 is controlled,
Since the electron beam output is increased, the sample temperature also increases.
It Sample temperature is t_TwoAfter that, period T _FourDuring the sample
Temperature is t_TwoController 12 powers so that
Control 10 Period T_FourAfter that, the power supply 10 will be controlled.
As the electron beam output is lowered, the sample temperature also drops.
To do. Sample temperature is t_ThreeAfter that, period T₆During the trial
Temperature is t_ThreeThe controller 12 keeps the
Control the source 10.

In this way, the sample placed in the concave portion 5a of the hearth 3 is heated and the inclusions are levitated on the sample surface, and then the controller 12 controls the motor power source 8 to drive the motor 7 to rotate it. The shaft 4 is rotated, and the sample placed in the next concave portion on the hearth 3 is placed at the electron beam irradiation position. Then, the sample is heated and dissolved in the same steps as described above. After the heating and melting process of all the samples was completed, the vacuum vessel was opened and each sample was taken out.
Those analyzes are performed by EPMA or a scanning electron microscope.

Although the embodiment of the present invention has been described above, the present invention is not limited to this embodiment. For example, the dissolution state holding period may be changed in two or more steps, and the sample preheating period may not be maintained at a constant temperature depending on the sample.

[0017]

As described above, in the method of dissolving inclusion sample according to the present invention, the temperature of the sample is measured, and the measurement temperature is maintained so that the sample temperature is maintained at the predetermined melting temperature for a predetermined period. Since the electron beam irradiating the sample is controlled based on the above, it becomes possible to ideally control the dissolved state of the sample, and almost all the inclusions in the metal sample can be levitated to the sample surface. . In particular, MgO and Si that could not be levitated efficiently in the past
Inclusions such as O ₂ can also be appropriately floated on the sample surface by the present invention. In addition, it became possible to fully automate the heating control of the sample.

[Brief description of drawings]

FIG. 1 is a diagram showing a relationship between an electron beam output and time in a conventional method.

FIG. 2 is a diagram showing an example of an apparatus for carrying out the method for dissolving inclusion samples according to the present invention.

FIG. 3 is a diagram showing a relationship between temperature and time of a sample in one example of the present invention.

[Explanation of symbols]

 1 Device Main Body 2 Vacuum Vessel 3 Hearth 4 Rotating Shaft 5 Recess 6 Sample 7 Motor 8 Motor Power 9 Electron Gun 10 Electron Gun Power 11 Temperature Sensor 12 Controller 13 Memory

Claims (2)

[Claims] 1. A method for dissolving an inclusion sample in which a sample on a hearth provided in a vacuum vessel is irradiated with an electron beam to dissolve the sample, and inclusions contained in the sample are floated on the surface thereof. When melting the sample, the temperature of the sample is measured, and the inclusion sample is designed to control the electron beam irradiating the sample based on the measured temperature so that the sample temperature is maintained at a predetermined melting temperature for a predetermined period. Dissolution method. 2. Irradiating the sample based on the measured temperature so that the sample temperature is maintained at a predetermined sample preheating temperature during the sample preheating period before the period when the sample is maintained at the melting temperature. The method for dissolving inclusion sample according to claim 1, wherein the electron beam to be controlled is controlled.